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-i»-^^>*'J» •' 



I 



ELEOTEO-THERMAL METHODS OF 
mOl^ AND STEEL PRODUCTION 



ELECTRO-THERMAL METHODS OF 
mON AND STEEL PRODUCTION 

BT 

JOHN B. C. KEESMW, F.I.C. 

WITH AN INTRODUCTION BY 

DE. J. A. FLEMING. F.R.S. 

>1 



ILLUSTRATED BY 
50 Tables and 93 Diatiravts and Photographs 



NEW YOEK 

D. VAN NOSTRAND CO. 

TWENTY-FIYE PAEK PLACE 

1914 



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Vx^ 



f. 






• : / : •. .- 






* • 






w .-• :i 



.>\ 



PKEFACE 

The Electnc Furnace is now firmly established as a useful 
adjunct of the blast-furnace, Bessemer converter, and open- 
hearth furnace in all the important iron and steel producing 
countries of the world. The Author's purpose in preparing this 
handbook has been to amplify and bring up to date the informa- 
tion relating to electric methods of smelting and refining iron and 
steel that was presented in an earlier handbook published in 
1907.^ 

In Chapters I. and 11. of the present work a general sketch of 
the scientific principles of electric heating is given, together with 
the broad lines of electric furnace design, in so far as these relate 
to furnaces for the smelting or refining of iron or steel. The 
theoretical side of the subject has not been dealt with more fully, 
because the ^ handbook is intended for the men actually engaged 
in the steel industry rather than for the designers and con- 
structors of large furnaces. It has seemed to the Author 
that full details of actual installations, and of methods of operation 
of the various types of furnace described, with summaries of 
working costs and tests of the raw materials and finished steel, 
would be more valuable to the practical steel-maker than a more 
extended treatment of the theoretical and mathematical side of the 
subject, especially as many of the data required for electric 
furnace calculations require verification or are altogether non- 
existent. The greater portion of the handbook is therefore devoted 
to the practical application of electric heating in the Iron and 
Steel industry, the improvements that have been made in the 
leading types of furnace, either in design or in methods of work, 

1 ** The Electric Furnace ia Iroa and Steel Production,*' by John B. C 
Kershaw : The Electrician Printing and Publishing Co., London. 



306489 



vi PREFACE 

during the period 1907 — 1912 being dealt with at considerable 
length in Chapters III. to VIII. 

Chapters IX. and X. contain descriptions and other details of 
a large number of the less well-known furnaces, many of 
novel design, which are at present passing through the experi- 
mental stages of their industrial development, while Chapter XI. 
contains a summary of all the figures given in the previous 
Chapters of the handbook relating to Power consumption and 
working costs. 

The Author is not connected by business relations with any of 
the patentees or companies exploiting the furnaces described ; 
this fact should give added value to the handbook, and to the 
judgments expressed upon the various furnaces and processes 
dealt with. 

The Appendix contains a large amount of useful information 
which it was not possible to incorporate in the body of the 
handbook. This includes (1) a list (based on official information) 
of all the electric furnaces for Iron and Steel Production in opera- 
tion or under construction in 1912 ; (2) The titles and dates of all 
the more important British Patents relating to the subject and 
granted during the period 1901 — 1912 ; (3) Reprints in full of the 
text of British Patents which are of special interest, and (4) 
Abstracts of and notes from recent valuable papers on Electric 
refining. 

That a practical work of this character, bringing together 
within one cover much scattered information was called for, is 
proved by the following quotation from the Journal of the Iron 
and Steel Institute for 1910. 

" Every steel manufacturer found a difficulty in comparing the 
statements of the various makers of electric furnaces, and in 
deciding which one he should adopt; and the expense was 
obviously too great for anyone personally to consider the inves- 
tigation of the respective merits of those furnaces." (J. H. 
Heap, in Discussion on Campbell's paper upon " Electric Steel 
Refining.") 



PEEFACE vii 

In the preparation of the handbook, which the Author believes 
will meet the above need, facts and data have been used from 
many and varied sources. The more important and valuable 
papers and articles that have been contributed on the subject to 
Scientific Societies, or have appeared in the Technical Press 
during the last five years, have been largely drawn upon ; and the 
information they contain has been supplemented by that obtained 
by the Author directly from the Patentees and Users of the 
various furnaces described. Very full references to all the original 
literature are given in the course of the handbook, so that 
readers may consult this when it is necessary to obtain further 
information. 

The Author's thanks are due to the following Firms and 
individuals who have assisted him in the preparation of the 
handbook, either by the provision of facts and other data, or by 
the loan of drawings and photographs : — 

Messrs. Siemen & Halske, Berlin. 

Soci^te des ^tablissments Keller, Leleux, et Gie, Livet. 

Societe ifilectrometallurgique Pran9aise, Proges. 

Societe £lectrom6tallurgique Proced6s Paul Girod, Ugine. 

Dr. Viktor Engelhardt, Berlin. 

M. Henri Dolter, Paris. 

Signor Ernesto Stassano, Turin. 

M. Paul Girod, Ugine. 

M. Albert Hiorth, Christiania. 

Mr. Donald F. Campbell, London. 

Mr. T. Scott Anderson, Sheffield. 

Mr, Victor Stobie, Newcastle. 

The Grondal Kjellin Co., London. 

Messrs. Edgar Allen & Co., Sheffield. 

The American Electric Furnace Co., New York. 

The Ajax Metal Co., Philadelphia. 

C. W. Leavitt & Co., New York. 

M. Paul Heroult, New York. 

Herr C. H. Vom Baur, New York. 



viii PEEFACE 

To the Editors and Publishers of the following Journals, the 
Author has also to express his indebtedness for their permission to 
reproduce illustrations, and to quote freely from articles, that have 
appeared in their pages :— 

Elektrotechnische Zeitschrifty Berlin. 

The Engineer, London. 

Metallurgical and Chemical Engineering, New York. 

The Iron Trade Review, Cleveland. 

Transactions of the Faraday Society, London. 

Transactions American Electrochemical Society. 

Finally, the Author must express his very great thanks to 
Professor Donnan, F.R.S., who kindly looked over the MS. of 
Chapters I. and IL, to Mr. John E. Raworth, C. P. A., of London, 
who has given much time to the preparation of the list of British 
Patents which appears in the Appendix, and especially to Dr. J. A. 
Fleming, F.E.S., London, for kindly consenting to write an Intro- 
duction to the Handbook. 



JOHN B. C. KERSHAW. 



The West Lancashire Laboratory, 
Waterloo, Liverpool. 
June, 1913. 



INTRODUCTION 

It hardly seems necessary for the Writer to introduce a work 
on ** Electro-Thermal Methods of Iron and Steel Production" by an 
Author already so well known as Mr. Kershaw. Nevertheless it 
is an advantage to have the opportunity of recommending to 
those specially interested in the Iron and Steel Industries this 
careful endeavour to furnish precise technical information on so 
important a subject. The applications of the heat-producing 
powers of the electric current have of late years become 
increasingly valuable, both in domestic and manufacturing work, 
and are no longer to be regarded as merely experimental or 
tentative. The Writer endeavoured to set these out briefly in 
some Cantor Lectures on the " Applications of Electric Heating," 
given at the Royal Society of Arts in March, 1911. 

The whole field of Electrometallurgy is one in which a great 
harvest of extremely useful achievement is still waiting to be 
reaped in the future, as it has been in the past. There seems to 
be no part of the manufacturing domain in which the electric 
current is not proving itself to be an implement of immense 
power. The Iron and Steel industries of this country hold such 
a predominant position that any innovation which seems likely 
to disturb existing methods of manufacture ought to be carefully 
investigated. The Electric furnace in its various forms, is no 
longer a mere laboratory instrument. It has taken a place 
as an operative agent, side by side with older appliances for the 
conduct of metallurgical operations. 

The questions which the Iron and Steel manufacturer desires 
to have answered are, first, whether the electric furnace methods 
can produce Iron and Steel having any improved qualities, apart 
from cost, and, secondly, if any advantage in respect of quality can 



X INTRODUCTION 

be demonstrated whether the process can compete from the point 
of view of costs, with the furnace methods based on combustion. 

Mr. Kershaw's book has for its object to give some exact 
information on these points, and to show how far the electro- 
thermal processes have demonstrated their advantage at present. 

When a new application of electricity comes to the front there 
is always a tendency to underrate or over-rate its value. When 
the telephone was first invented official electricians laughed at it 
as a toy, but before long its proved practical value induced them 
to put into operation legal machinery to control its use, and 
enabled a Government Department to take Royalties for twenty 
years (reckoned in hundreds of thousands of pounds) for license 
to employ it. 

At the inception of electric-lighting the public were led to 
believe in an immediate triumph over gas-lighting, but twenty 
years had to elapse before the older illuminant began to be seriously 
affected by the younger. 

The real difficulties which arise in these new departures are 
never those that are anticipated, but are always something quite 
unexpected. 

In the light of such experiences, therefore, no cautious person 
would assume that a new thermal process will undercut the older 
furnace method, in a brief space of time. 

On the other hand, the advice to " wait and see,'' if followed too 
far, is one which is not seldom accompanied by the unpleasant 
experience of transferring business profits to other pockets than 
those of the " tvaiter." 

The matter which lies at the foot of all technical applications 
of electricity is the cost per unit of producing electric energy. It 
is commonly assumed that countries rich in water-power have a 
position of supremacy as regards the production of a cheap supply 
of electric energy. It has, however, been demonstrated that the 
production of electric energy by the combustion of coal has not 
by any means reached its lowest limit of cost in Great Britain, 
and that if scientific methods and developments are brought to 



INTRODUCTION xi 

bear upon the problem, we have no reason to fear that a country 
rich in coal strata, like Great Britain, will be at immeasurable 
disadvantage when compared with countries rich in water-power. 

The first aspect of the subject is, however, the intrinsic 
advantage of electric furnace methods over combustion methods. 
If distinct superiority in the quality of the material produced can 
be demonstrated, then the question of cost of production will be 
more readily attacked. 

Mr. Kershaw's book may therefore be strongly recommended 
to those iron and steel manufacturers who are first concerned to 
know what has already been done, and what are the proved points 
of value in the electrical methods of production. The various 
forms of electric furnace in use are fully described, and the 
question of costs of working are discussed, from the point of view 
of experimental results. 

The electrical processes seem to have particular advantages in 
the production of special or alloy steel, which are of increasing 
importance. 

Whilst the classical blast-furnace method for pig-iron production 
is not likely to be affected for a long time to come (at least in this 
country), there are nevertheless subsidiary operations in steel 
production in which the electrical methods are likely to prove 
their superiority soon ; and a Book which deals in an impartial 
and critical spirit with the facts of experience is therefore of 
particular value to the Iron and Steel metallurgist who is desirous 
of precise information in order to determine his position as 
regards the newer methods. Lord Bacon tells us in one of his 
Essays, that truth emerges more readily from error than from 
confusion ; and hence the first step in attaining the truth is to set 
out the facts, and view them steadily and as a whole. 

This Book will enable the reader to do it as far as concerns the 
electrical production of Iron and Steel. 

J. A. FLEMING. 

University College, 

London. 
March, 1913. 



CONTENTS 



CHAPTER 

I. General Eeview of Progress in Period 1907—1912 



PAGE 

1—7 



II. General Principles of Electric Heating and 
Classification of Furnaces. Notes on Elec- 
trodes AND EeFRACTORY MATERIALS FOR LiNINGS , 



J— 19 



in. Electric Smelting Furnaces 20—42 

1. Early Trials at Darfo, Livet, and Sault Sainte 

Marie 20—23 

2. Eecent Trials 

(a) The Trials at Ludvika and Domnarfvet . 23 — 32 

(b) The Trials at Heroult 32—38 

(c) The Frick and Chaplet Furnaces . . . 38 — 41 

3. Comparative Yields and Costs .... 41 — 42 



rv. The Heroult Electric Steel Eefining Furnace . 43 — 66 

(a) General Description 46 — 50 

(b) The Chicago 15-ton Furnace 50 — o3 

(c) Method of Working the Chicago Furnace . . 53 — 55 

(d) Charge Sheets and Working Costs of the Chicago 

Furnace 55—59 

(e) The Heroult Furnace at Worcester ... 60 

(f) Other Installations 60 — 64 

(g) Power Consumption 65 

(h) Future Developments 66 

V. The Girod Electric Steel-Eefining Furnace . . 67 — 88 

(a) General Description 68 — 69 

(b) Description of Latest Furnace .... 70 — 72 

(c) Methods of Working the latest Furnaces . . 72 — 79 

(d) Power Consumption and Working Costs . . 80 — 82 

(e) Chemical and Physical Tests of the Raw Material 

and Finished Steel 83 — 85 

(f) Notable Installa4ions of the Girod Furnace . . 85 — 87 

(g) Future Developments 87 — 88 



xiv CONTENTS 

CHAPTER ''■^^^ 

VL The Stassano Electric Steel Ftjbnace and Process 89 — 106 

(a) Historical Notes 89—91 

(b) General Description of Earlier Types of Rotary 

Furnace 91—94 

(c) Power Consumption and Working Costs of . 94 — 95 

(d) The New Form of Eotary Furnace . . . 95—98 

(e) Future Developments 98 — 100 

(f) Notable Installations 100—103 

(g) Chemical and Physical Tests of the Finished Steel 104—105 



Vn. The Kjellin and Eochling-Eodenhauser Steel 

Eefining Furnaces 106—127 

(a) General Description of Kjellin Furnace . . 106 

(b) Methods of Work with 107 

(c) Power Consumption 108 — 109 

(d) Defects of 110 

(e) General Description of Eochling-Bodenhauser 

Combined Furnace Ill — 112 

(f) Methods of Working with 113—116 

(g) Power Consumption and Working Costs . . 117 — 120 
(h) Chemical and Physical Tests of the Finished 

Steel 121 

(i) Notable Installations of the Combined Type of 

Furnace 121—125 

(j) Current and Voltage Curves for the Kjellin and 

Eochling-Eodenhauser Furnaces . . . 126—127 



^? 



VilL. The Keller Electric Steel Eefining Furnace . 128—137 

(a) Historical Notes 128 

(b) Description of 8-ton Furnace at Unieux . . 129 — 131 

(c) Power Consumption and Working Costs of . 131 

(d) Description of New Type of Conducting-Hearth 

Furnace 132—137 



IX. Other Types of Electric Furnace for Steel 

Eefining 138—163 

(a) The Frick Furnace 138—140 

(b) The Gronwall Furnace 140—143 

(c) The Hiorth Furnace 143—149 

(d) The Stobie Furnace 149—153 



CONTENTS 



XV 



CHAPTER 



X. 



Other Types of Electric Furnace for Steel 
Eefining (continued) 



(a) The 

(b) The 

(c) The 

(d) The 

(e) The 

(f) The 

(g) The 
(h) The 
(i) The 
(J) The 
(k) The 



Anderson Furnace 

Chaplet Furnace . 

Colby Furnace 

Greene Furnace and Method 

Harden "Paragon" Furnace 

Hering ** Pinch Effect " Furnace 

Nau Furnace and Process . 

Nathusius Furnace 

Queneau Furnace and Method 

Beid Furnace 

Soderberg Furnace 



PAGIi: 

154-172 

154 

155 
155—157 
157—160 
160—163 
163—168 
168—169 
169—171 

171 
171—172 

172 



XI. Comparative Power Consumption and Eunning 
Costs 

(a) The Heroult Furnace and Process 

(b) The Girod Furnace and Process .... 

(c) The Stassano Furnace and Process 

(d) The Kjellin and Bochling-Bodenhauser Furnaces 

and Processes 

(e) The Keller Furnace and Process 

(f ) The Frick Furnace and Process .... 

(g) The Hiorth Furnace and Process 

(h) The Colby Furnace and Process .... 
Table XLIX. Tabular Statement of all Figures for 

Power Consumption 

Table L. Tabular Statement of Chemical and 

Physical Tests of Finished Steel ... 



173-187 

174—175 
175—178 
178—179 

180—183 

183—184 

184 

184 

184—185 

186 
187 



APPENDIX 



I. Lists of Electric Furnaces for Iron and Steel Pro- 
duction IN Operation or under Construction in 
1912 

A. Iron Smelting Furnaces in Europe 

B. Heroult Steel Eefining Furnaces 

C. Girod Steel Eefining Furnaces .... 

D. Kjellin and Eochling - Eodenhauser Steel 

Eefining Furnaces 

E Keller Steel Eefining Furnaces .... 



188-195 

188 

189—191 

192 

193—195 
195 



xvi CONTENTS 

APPKNDIX PACE 

II. Lists of English and Foreign Patents Eelating to 
Electric Furnaces for Iron and Steel Produc- 
tion, GRANTED 1898 TO 1911 196 — 204 

A. List of English Patents, prepared by John E. 

Baworth 196—201 

B. List of Heroult Patents 201 

C. List of Girod Patents 202 

D. List of Kjellin and Bochling - Eodenhauser 

Patents 202- 204 

HI. Abstracts and Reprints of the Earlier Patents 
Eelating to Electric Furnaces for Iron and Steel 
Production 204—223 

A. Charles William Siemens. Patent No. 2110(1879) 204 

B. S. Z. de Ferranti „ 700 (1887) 204—206 
a Ernesto Stassano „ 11604(1898) 207—208 

D. Gustav Benedicks „ 18921 (1900) 208—210 

E, C. A. Keller „ 22584 (1900) 210—212 

F, Soc. l5lectro-m6talliirgique Fran9ai8e (Heroult) 

Patent No. 14486 (1901) 212—215 

G. Soc. £lectro-m6tallurgique Fran9aise (Heroult) 

Patent No. 14643(1901) 215—218 

H. C. A. Keller. Patent No. 24234 (1901) . . 218—219 

/. P. L. T. Heroult „ 3912 (1902) . . 219 

J. C. A. KeUer „ 16271 (1902) . . 219—223 

IV. Abstracts of Papers and Notes on Electric Steel 

Eefining 223—233 

A. The Function of the Slag in Electric Steel 

Eefining, by E. Amberg 223—229 

B. The use of Titanium in Foundry Practice with 

Electric Steel. (1) By Paul Girod. (2) Letter 

by N. Petinot 229—230 

0. Annual Eeview Article upon " Progress in 

Electric Furnaces," by Carl Hering . . . 230—232 

D. Notes on Work of Stassano Furnaces at New- 
castle, England, by J. B. 0. Kershaw . . 232—233 



LIST OF ILLUSTEATIONS. 



FIO. 



1. Diagram of Electric Arc Furnace 

2. Diagram of Electric Arc Furnace . 

3. Diagram of Electric Eesistance Furnace 
■ 4. Diagram of Electric Induction Furnace 

5. Siemens Crucible Furnace .... 

6. Siemens Crucible Furnace .... 
1. Stassano Arc Furnace (earliest type) 

8. Keller Shaft Furnace 

9. No. 1 Heroult Shaft Furnace (early type) 

10. No. 2 Heroult Shaft Furnace (Canadian type) 

11. No. 2 Gronwall Furnace (vertical section) . 

12. No. 2 Gronwall Furnace at Domnarfvet (external view) 

13. No. 3 Gronwall Furnace at Trollhatten (vertical section) 

14. No. 3 Gronwall Furnace at Trollhatten (external view) 

15. No. 3 Heroult Furnace, at Shasta, California 

16. No. 1 Lyon Heroult Furnace, at Shasta, California 

17. No. 1 Lyon Heroult Furnace (1,600 kw.), at Shasta, California 

18. Frick Reduction Furnace (sectional elevation) 

19. Heroult 3,000-kg. Furnace (early design) 

20. Heroult 3,000-kg. Furnace (early design) 

21. Heroult 2,500-kg. Furnace (latest design) 

22. Heroult 2,500-kg. Furnace (latest design) 

23. General View of the Steel Works at La Praz, France . 

24. Interior of Power Station at La Praz, France 

25. Heroult 15-ton Furnace at Worcester, U.S.A. 

26. Heroult 15-ton Furnace at Worcester (tipped for discliHrge) 

27. The Thury Regulating Apparatus at Braintree, Essex . 

28. The Braintree Heroult Furnace (discharging) 

29. Plan of original Girod Refining Furnace (2 tons) 

30. Sectional Elevation of Girod Refining Furnace 

31. Plan of latest 8- ton Girod Furnace 

32. Sectional Elevation of 8-ton Girod Furnace . 

33. Sectional Elevation of 8 -ton Girod Furnace . 

34. General View of 12-ton Girod Furnace at Ugine 

35. External Details of 12-ton Girod Furnace at Ugine 

36. Arrangement of Electrical Connection to Furnaces 

37. Arrangement of Water-cooling Pipes in Hearth of Girod Furnace 

38. General View of Ugine Steel Works 

E.T.M. h 



PAGE 

9 
10 
10 
11 
13 
13 
20 
21 
22 
22 
24 
25 
27 
28 
33 
35 
36 
39 

44 

4o 

46 

47 

48 

49 

52 

54 

62 

63 

68 

68 

69 

70 

71 

73 

75 

76 

77 
86 



iviii LIST OF ILLUSTRATIONS 

no. PAOK 

39. The Stassano Furnace earliest form 90 

40. The Stassano Botary Furnace, first form, in sectional eleration . 92 

41. The Stassano Botary Furnace, first form, in sectional elevation . 92 

42. The Stassano Rotary Furnace, latest form, in sectional elevation . 96 

43. The Stassano Botary Furnace, latest form (plan of) . . . 97 

44. The Stassano Botary Furnace (250 h.p.) at the Boyal Arsenal, 

Turin 98 

45. The Stassano Botary Furnace (250 h.p.) at the Boyal Arsenal, 

Turin. . / 99 

46. The Stassano Furnace at the Works of the Electro-Flex Steel Co., 

Newcastle, England 100 

47. The Stassano Furnaces at Newcastle, casting room . . .101 

48. The Stassano Furnaces at Newcastle (di^harging) . . . 102 

49. The early type of Kjellin Furnace (elevation) .... 107 

50. The early type of Kjellin Furnace (plan) 108 

51. The 1,500-kg. Kjellin Furnace at Gysinge in operation . . 109 

52. The Bochling-Bodenhauser Single-phase Furnace (elevation and 

plan) Ill 

53. A Bochling-Bodenhauser Three-phase Furnace, under con- 

struction 112 

54. A Bochling-Bodenhauser Three-phase Furnace, under con- 

struction 114 

55. A Bochling-Bodenhauser Single-phase Furnace being charged 

with molten metal 115 

56. A Bochling-Bodenhauser Single-phase Furnace (discharging) . 116 

57. Details of Transformer Construction for Kjellin Furnace . .123 

58. Details of Transformer Construction for Bochling-Bodenhauser 

Three-phase Furnace 124 

59. Details of Transformer Construction for Bochling-Bodenhauser 

Three-phase Furnace 125 

60. Graphic Bepresentation of Power Bequirements of Kjellin and 

Bochling-Bodenhauser Furnaces 126 

61. Keller's Furnace (early type, diagrammatic section) . . . 128 

62. Keller's 8,000-kg. Furnace at Unieux (j^ection) . . . .129 

63. Keller's 8,000-kg. Furnace at Unieux (plan) .... 130 

64. Keller's Furnace with Conducting Hearth (sectional elevation) . 132 

65. Keller s Furnace with Conducting Hearth (plan) . . . .133 
t)6, Keller's Furnace with Conducting Hearth (section showing method 

of supporting the electrodes) 134 

67. Details of Electrode Support for Keller's Furnace . . . .135 

68. General View of Keller's Conducting Hearth Furnace . . .136 

69. Keller's Conducting Hearth Furnace being charged with molten 

metal 137 

70. Diagrammatic section of the Frick Furnace 139 

71. Section of Gronwall Furnace 141 

72. Section of Gronwall Furnace . 141 



LIST OP ILLUSTEATIONS 



XIX 



FIG. 

73. 
74. 
75. 

76. 
77. 

78. 
79. 
80. 
81. 

82. 
83. 
84. 
85. 
86. 
87. 
88. 
89. 
90. 
91. 
92. 



r 



dis 



Diagram of Electric Circuits in Hiorth Furnace . 
Section of Hiorth 5 -ton Furnace at Jossingfjord . 
Section of Hiorth 5-ton Furnace at Jossingfjord, tipped fo 

charging . 

Exteroal details of Hiorth 5-ton Furnace at Jossingfjord 
Top view of Hiorth 5-ton Furnace at Jossingfjord 
Diagram of Hiorth*s 30-ton Furnace .... 
Diagrammatic section of Stobie's Two-phase Furnace . 
Diagrammatic section of Stobie's Three-phase Furnace . 
Diagrammatic section of Stobie's Combined Electric, and Gas or 

Oil-heated Furnace 

Anderson Furnace (sectional elevation) . 

Chaplet Furnace in diagrammatic section 

A Colby Furnace in operation at Chicago 

Induction Furnace arranged for working Greene's Process 

Harden 's Paragon Furnace in sectional elevation . 

Harden's Paragon Furnace (plan) 

Hering Furnace in diagrammatic sectional elevation 
Hering Furnace (sectional elevation and plan) 
Nathusius Furnace (sectional elevation) 

Nathusius Furnace in operation 

Eeid Furnace, experimental type 



PAOE 

142 
li3 

144 
147 
148 
150 
151 
152 

153 
154 
155 
156 
158 
161 
162 
164 
165 
169 
170 
172 



LIST OF TABLES- 



GENEEAL TABLES. 

TABLE PAGE 

I. Kw. hours required for the production of one ton of 
Iron or Steel in various T3'pes of Furnace (Kershaw, 

1906) 18 

II. Kw. hours required for the production of one ton of 
Iron or Steel in a Rochling-Rodeiihauser Furnace 
(Engelhardt, 1910) 19 



Pig Iron Production. 

III. Average Figures for one Month's continuous Work at 

Trollhatten 31 

IV. Comparative Power Consumptions and Costs for various 

Furnaces 41 



Steel Eefining by the Herotjlt Furnace. 

V. Furnace Charge-sheet of 15 -ton Furnace at Works of 

Illinois Steel Co., Chicago, U.S.A. . . . 65-56 

VI. Average Figures for 15 -ton Furnace at Works of Illinois 

Steel Co., Chicago, U.S.A. 58 

VII. Average Figures for 15- ton Furnace at Works of Illinois 

Steel Co., U.S. A 58 

VIII. Chemical Composition of the Steel produced ... 59 
IX. Charge-sheet for 2J-ton Furnace at Ija Praz, France . 65 



Steel Eefining by the Girod Furnace. 

X. Eefining Costs at Ugine, in France (Cold Charges) . . 81 
XI. Eefining Costs at Ugine, in France (Molten Charges) . 81 
XII. Chemical Composition of Scrap Metal used and of Eefined 

Metal produced, at Ugine 83 

XIII. Chemical Composition of various Classes of Steel produced 

at Ugine 83 

XIV. Physical Tests of various Classes of Steel produced at 

Ugine 84 



xxii LIST OF TABLES 

Steel Eefining by the Girod Furnace {contiiiued), 

TABLE PAOE 

XV. Physical Tests of various Classes of Steel produced at 

ITgine 84 

XVI. Physical Tests of various Classes of Steel produced at 

Ugine 86 



Steel Befinikg by the Stassano Furnace. 

XVII. Power Consumption for various Classes of Steel at Turin 94 

XVIli. Working Costs at Turin 95 

XIX. Working Costs at Bonn 95 

XX. Chemical and Physical Tests of Soft Steels for Castings . 104 
XXI. Chemical and Physical Tests of Hard Steels for Pro- 
jectiles 104-105 

XXII. Chemical Tests of Special Steels 105 



Steel Eefining by the Kjellin and Eochling-Eodenhauser 

Furnace. 

XXIII. Working Costs of a 2 -ton E. E. Furnace at Volklingen, 

using Cold Scrap 117-118 

XXI V. Working Costs of a 2-ton E. E. Furnace at Dommeldingen, 

using Molten Metal from Mixer 118 

XXV. Working Costs of a 2-ton E. E. Furnace, using Molten 

Metal from Cupola 119 

XXVI. Production Costs of Steel for Eails and of Steel for Boiler 

Plates, in a 7-tou E. E. Furnace . . . .119 

XXVII. Working Costs of o-ton E. E. Furnace at Dommeldingen 120 
XXVIII. Chemical and Physical Tests of High and Low Carbon 

Steels .......... 121 

XXIX. Chemical Tests of various Steels made in the E. E. 

Furnace 121 

XXX. Physical Tests of various Steels made in the E. E. 

Furnace 122 



Steel Eefining by various Furnaces. 

XXXI. Charge-sheet for the 8-ton Keller Furnace at Unieux, 
France, with Chemical Composition of the Charged 
Scrap and Finished Steel 131 

XXXII. Working Figures for the Frick Furnace at Essen, 

Germany 139 

XXXIII. Charge-sheet for the 5-ton Hiorth Furnace, at Jossing- 

fjord, Norway . 145 



LIST OF TABLES ' xxiii 

Steel Eefining by various Furnaces (cmiinued). 

TABLE PAGE 

XXXIV. Chemical Composition of Raw Materials used and of Steel 

produced, at Jossingfjord 146 

XXXV. Comparative data of 5-ton and 30-ton Hiorth Furnaces . 149 

XXXVI. Chemical Tests of the Raw Materials used and Finished 

Steel produced by the Greene Furnace . . .159 

Comparative Power Consumptions and Running Costs, etc. 

XXXVII. Costs of refining Cold Charges, Girod Furnace . .176 
XXXVIII. Costs of refining Molten Charges, Girod Furnace . .177 
XXXIX. Chemical Tests of Raw Materials and Finished Steel at 

Ugine 177 

XL. Power Consumption of Stassano Furnace at Turin . .178 
XLI. Costs of Refining by Stassano Furnace at Bonn . .178 
XLII. Chemical and Physical Tests of Soft Steels made in 

Stassano Furnace 179 

XLIir. Chemical and Physical Tests of Hard Steels made in 

Stassano Furnace . . . . . . .179 

XLIV. Working Costs for a 2-ton R. R. Furnace using Cold 

Metal 180-181 

XLV. Working Costs for a o-ton R. R. Furnace using Molten 

Metal 181-182 

XL VI. Working Costs for a 6 -ton R. R. Furnace using Molten 

Metal .......... 182 

XLVII. Working Costs for a 6-ton R. R. Furnace using Molten 

Metal 183 

XL VIII. Power Consumption and Chemical Tests for 8-ton Keller 

Furnace at Uuieux 184 



SUMMARY TABLES. 

XLIX. Power Consumption for all Types of Furnace, in kw. 

hours per metric ton of Steel produced . . .186 
L. Chemical and Physical Tests of the Raw Materials used 

and of the Steels produced, by all Types of Furnace . 187 






1 .,«?<»■'•»** 



^ >» J "" J 1 o •• ^ • 



ELECTRO-THERMAL METHODS OF 
IRON AND STEEL PRODUCTION. 



CHAPTER I 



INTRODUCTION 



In a small handbook entitled " The Electric Furnace in Iron 
and Steel Production " published in London in the year 1907,^ 
the writer, after describing all the well-known types of electric 
furnace, summarised the position at that date, in the following 
words : — 



a n 



The use of the electric furnace for iron pre reduction is, therefore, 
in the writer's opinion, not likely to undergo any industrial develop- 
ment at present, excepting under very special conditions. 

"In countries like Norway and Switzerland, with abundance of 
water-power that can be developed at very low cost, it is possible that a 
native iron-smelting industry might be established, if iron ore and lime 
are found in the locaHty of the water-power. But here, again, special 
conditions will be required to render the industry a financial success, 
and it is unlikely that the iron will be able to compete in price in the 
open market, with the product of the ordinary blast-furnace. 

• •••••• ••• 

" Taking the cost of the electrical horse-power year at £2 and the 
average power consumption in Table 1 we have the following costs : — 

1. Steel from molten scrap, 2s. Qd. (400 kw. hours). 

2. Steel from cold scrap and pig, 5s. Od. (800 kw. hours). 

3. Pig-iron from ore, coke and lime, charged cold, 15s. 6 J. 

(2,500 kw. hours). 

4. Pig-iron from ore, coke and lime-charged hot, 125. 5c7. (2,000 kw. 

hours)." 

1 The Electrician Printing and Publishing Co., Ltd. 
E.T.M. B 



• « • • 



2 -v. ; ;/: tELECTRaTHERMAL METHODS 

In the manufacture of best crucible steel, however, it is customary to 
assume thatT)etween 2^ and 3 tons of coke are consumed per ton of 
steel produced. At the present market price of coke ( 1 Is.) the advantage 
is, therefore, on the side of the electric refining furnace. 

As regards the electric smelting processes, it is necessary to remember 
that coke is still required to reduce the oxide of the iron ore to the 
metallic state, and that the only fuel saved is that used in the blast 
furnace for heating purposes. In the best modern smelting practice 
only 16 cwts. of coke are required per ton of pig-iron produced, and of 
this total 6*5 cwts. are required to reduce the ore. The saving in coke 
by the electric furnace method of smelting cannot, therefore, exceed 
9*5 cwts., or at the present price of ooke, Ss. Od. 

These considerations show that the prospects for the electric refining 
processes are much brighter than those for the electric smelting pro- 
cesses, since the saving of coke in the latter is too small to balance the 
large expenditure upon electric power. The horse-power year would, 
in fact, have to be supplied at the extraordinarily low cost of £1 in 
order to compete with the modern blast furnace, and the localities 
where it can be produced at this figure are certainly few in number. 
For the present, therefore, the application of the electric furnace in the 
iron and steel industries is likely to be restricted as a general rule to 
the refining processes by >yhich pig- and scrap-steel are converted into 
higher-priced products. In these branches it is likely to be very widely 
employed, and to have a most important effect upon the future develop- 
ment of the whole iron and steel industry. 

The developments of the five years that have elapsed since 
the above lines were written have to some extent proved the 
correctness of the forecast. Electric steel-refining furnaces and 
processes are widely employed by progressive steel-makers in 
both Europe and America, and, as shown by the list of furnaces 
given in the Appendix of this volume, the electrical steel industry 
is already well established and of considerable importance. The 
electric smelting industry on the other hand, has only made 
headway in two countries where the special conditions referred 
to above have been found favourable to its development, namely, 
in Sweden and in California ; and in the former country only 
can a healthy and progressive industry be said to exist. While 
the annual output of electric pig-iron and pig-steel is still too 
small to be recorded, the annual production of electrically 



INTRODUCTION 3 

refined steel has grown from 30,000 tons in 1908 to over 200,000 
tons in 1912; and when the larger furnaces that are now being 
installed commence to produce steel, the output will be greatly 
increased and may attain 250,000 tons per annum. 

Compared with the world's total output of steel, these totals 
are of course small and insignificant ; but when one realises 
that only ten years ago electric steel was largely a novelty, and 
that the steel manufacturing industry, owing to its age and 
importance, and also to the capital invested in it, is one of the 
most conservative and settled of all industries, the progress made 
in the period 1907 — 1912 is seen to have been quite notable, and, 
considering all the circumstances of the case, remarkably rapid. 

Two other forecasts of the writer relating to the development 
of electric steel refining are also now in course of realisation, 
namely, the restriction of the electric furnace to the last stage 
only of the steel-making process, and the use of blast-furnace or 
coke-oven gases for generating the electric energy required. In 
Germany, at the works of Le Gallais Metz & Co., at Dommel- 
dingen, and also in America, at one of the large works in Chicago 
owned by the United States Steel Corporation, gas-engines using 
the waste-gases of the blast-furnaces, provide a large portion of 
the current required by the electric refining furnaces. A similar 
system of power generation is to be employed at a large iron 
works in the North of England, where an electric plant is now 
being installed. In this last case, coke-oven gases are to be 
used in conjunction with the waste gases from blast-furnaces for 
driving the gas-engines ; and the whole plant, including rolling- 
mills, blowing-engines, auxiliary motors, and electric and open- 
hearth furnaces, will be operated without burning a single ton of 
solid fuel for either power or heating purposes. According to 
Campbell, the costs of power at this installation will be under 
•25d. per kw. hour, and if the plant is well designed and repairs 
are not unusually heavy, the cost may be found to work out 25 
per cent, below this estimate. 

As regards the advances in other directions, the capacity of the 

b2 



4 ELECTKO-THERMAL METHODS 

furnaces has been increased five-fold, and the power consumption 
reduced by 33 per cent, in the period under review. In 1907, the 
Heroult furnaces at La Praz, taking 480 kw. and producing 
3 tons of metal at one heat, were the largest in actual use; 
whereas in 1912 furnaces producing 15 to 25 tons of metal per 
charge, and consuming 2,000 to 3,000 kw. of electrical energy, 
have been installed both in Germany and America, and are 
yielding good results. 

The chief advantages obtained with these large furnaces are 
that radiation losses are reduced, and that a metal possessing 
more uniform chemical and physical properties can be obtained 
than from a succession of small heats. As regards power-con- 
sumption, the best average results obtained in 1907 were 800 kw. 
hours per ton (2,000 lbs.) of metal produced, using cold scrap as 
raw material, whereas to-day, returns for a recently erected 
refining furnace show a reduction of 28 per cent, on these 
figures and a consumption of only 575 kw. hours under similar 
conditions of work. The consumption and cost of electrodes 
have also been reduced CO per cent, during the past five years, by 
many improvements in the method of manufacture and of use. 
Further savings in this direction may no doubt be expected. 

Turning now to the field of application for the electric furnace 
in the steel industry, we find that whereas five years ago, only 
the finer and higher priced varieties of tool-steel and special 
alloys were being manufactured, to-day it is being employed for a 
great variety of products, including steel for axles and tyres, gun- 
steel, billets for wire and plates, and rail and girder steel. The 
application of the electric furnace as a heating furnace only, in 
the production of fine castings is also extending, and in 
Germany, France, England and America, several installations of 
this character can now be found in operation. The advantage 
here is, that the higher temperature obtained by the electric 
method of heating yields a more fluid metal, and a better separa- 
tion of the gaseous and other impurities of the steel is thereby 
obtained. 



INTRODUCTION 5 

According to Heroult {Transactions of the 8th International 
Congress of Applied Chemistry^ New York, Sept. 1912), it has 
been found quite unnecessary to anneal some of the low-carbon 
steels for casting purposes made in the electric furnace, the 
chemical and physical properties of these steels being quite equal 
to those of the best brands of rolled or hammered mild steel made 
by the ordinary methods. 

Another application of the electric furnace which has been 
found most valuable, is as a melter and mixer of the mis- 
cellaneous scrap alloys and scrap steels which accumulate in all 
foundries where the special steels are made. Chrome, nickel, 
and vanadium steels for automobile castings can be manufactured 
by melting miscellaneous steel alloy scrap, and by making the 
necewsary additions to bring the composition up to the required 
specification. Another application which is being developed at 
the present moment is that of using an electric furnace for 
maintaining steel in a ** resting " state at a pouring heat, for one 
or two hours, in order to allow a more complete separation of the 
slag and gases entangled in the molten metal. 

The extension of the field of application of the electric furnace 
in the steel industry, from the production of high-class crucible 
steel, through the intermediate grades of steel, to that of rail and 
constructional steel has, however, been one of the most striking 
features of the development of the past five years. 

The question that now demands an answer is : — Can this 
extension be justified by the results obtained, and can the electric 
finishing process be employed to supplement the open-hearth pro- 
cess of manufacture, for ordinary rail and girder steel ? On this 
particular point, opinion at present is sharply divided ; and in 
the writer's view, it will only be by the practical test of some 
years* experience that the question will be decided. Both in 
America and in Germany large quantities of rail-steel have 
already been made in the electric furnace, and these rails are 
now undergoing the tests of actual service on the railway 
systems of the two countries named. 



6 ELECTRO-THEEMAL METHODS 

Five thousand tons of electric steel rails have been laid on 
railway tracks out in the Western States of America, and it is 
reporced that, so far, not one single electric rail has failed. In 
Germany also very favourable experience has been obtained 
with these rails, and it is quite possible that the savings resulting 
from their longer life and greater freedom from breakage, may 
more than counterbalance the extra cost of the electrical treat- 
ment. For it must be understood that the electric furnace when 
applied to the production of rail and girder steel does not seek 
to eliminate the Bessemer or open-hearth furnace, but to take 
the metal they produce, and, by the application of special heat 
treatment in a neutral atmosphere, to carry the refining opera- 
tions a stage further, and thus to produce a purer and more 
durable metal. 

Serious railway accidents, due to rail breakages, have been 
increasingly common (especially in U.S.A.) in recent years, and 
any improvement in the quality of the rail steel that will lead to 
a reduction in the number of these accidents, may be quite worth 
paying for. 

However, whether such an extension of the use of the electric 
furnace is to occur at once in the United Kingdom, in Germany, 
and in America, or only with the gradual exhaustion of the coal 
supplies, its field of utility is already sufficiently wide and 
important, to justify a close study on the part of steel-makers of 
the developments of the past five years. 

The following extract from a paper read by Mr. Donald F. 
Camipbell, in London, in the autumn of 1911 (Transactions of 
the Faraday Society, Vol. VH., 1912), proves the necessity for 
study of what has already been achieved in this particular branch 
of electro-metallurgy, and may serve as a foreword to that more 
extended study of the subject which this book is designed to 
promote. 

It must be remembered that a large number of engineers of the 
highest technical training and international experience, are constantly 
engaged in improving furnace design and metallurgical methods, on 



INTEODUCTION 7 

behalf of powerful industrial organisations. Careful and expensive 
experimental work has been going on for years, and many of the 
furnaces and processes, which are continually being patented and 
published, have been tried and abandoned by those controlling large 
electro-metallurgical works. Irn/provement must he looked for by 
increasing the general efficiency of the best processes we have at the 
present time, rather than by radical changes in furnace construction. ^ 

In all questions of design, it is essential to bear in mind, first and 
foremost, the metallurgical requirements ; the electrical considerations 
always must take a purely secondary place. The neglect of this 
principle has caused the failure of the majority of the numerous furnaces 
that in recent years have been described in technical journals, but 
abandoned because they were based on incomplete theoretical data, with 
little or no commercial practice ; whereas the most successful electric 
steel furnace of to-day follows as closely as possible the best basic open^ 
hearth practice, with the simplest possible application of electrical heat 
energy, ^ 

1 The italics have been inserted by the author. 



CHAPTEK II 

GENERAL PRINCIPLES AND METHODS 

The electric furnace is an apparatus for developing and for 
applying the heat energy of an electric current to chemical 
or metallurgical purposes. 

All solids and liquids that allow an electric current to pass 
through them, while themselves undergoing no change, are 
called conductors. The amount of heat that can be generated by 
the passage of an electric current through a conductor, depends 
upon two factors only, (1) the strength of the current, and (2) the 
resistance offered by the conductor. 

Joule's law with regard to the development of this heat in 
solid and liquid conductors is expressed by the following equation, 
in which C represents the current in amperes, E represents 
the resistance of the conductor in ohms, and H represents the 
heat produced in calories per second : — 

H = C^ R X -24 

The temperature to which the conductor can be raised by the 
current must not be confused with the amount of heat y as calculated 
above and expressed in calories. The temperature to which the 
conductor can be raised, is limited by the losses due to convection, 
conduction and radiation ; and is expressed by the equation : — 

rp _ (H - Ha) 
" Ws 

in which H represents the calories (as before), W represents 
the weight of metal heated, s represents the specific heat of 
this metal, T represents the rise in temperature in degrees 
centigrade, and a represents the fractional heat losses due to 
radiation, etc. 



GENERAL PRINCIPLES AND METHODS 



These two equations do not apply however to the arc type of 
furnace, in which the arc produced hy the disruptive discharge of 
an electric current of high potential, through air, is employed as 
heating agent. As the temperature of the electric arc formed in 
air between carbon electrodes lies between 2,500*^ and 3,500° C. 
(4,500° and 6,300° F.), great heats can be attained in arc furnaces, 
and the ordinary laws of heat conduction and radiation are modified 
by dissociation phenomena, and by the change in the specific 
heats of molten metals and gases at these high temperatures. 
For each particular type of furnace there is also a limit, due to 
the creation of a state of equilibrium between the heat evolved 
per second and the heat dissipated 
per second by radiation and other 
causes. These losses are of course 
greater, the higher the temperature 
of the furnace walls. 

The electric furnaces used for 
iron and steel production may be 
divided into three classes : (1) Arc 
furnaces ; (2) Resistance furnaces ; 
(3) Induction furnaces, according to 
the different methods of applying the above principles of electric 
heating. 

In the Arc furnaces the heat effect is produced by radiation or 
conduction from an electric arc. This arc is formed by the passage 
of an electric current at 50 to 120 volts pressure or E.M.F. 
across the air-gap that exists between two carbon electrodes, 
or between one or more carbon electrodes and the surface of the 
molten metal, which then acts as the second pole of the electrical 
circuit. In the former case the carbon electrodes are fixed at an 
angle of between 30° and 45° with the horizontal plane, and their 
terminals are held just above the surface of the metal being 
heated. The Stassano represents the first type; the Heroult 
furnace the second. 

In Class (2), Resistance furnaces, the heat effect is produced 




Fig. 1. — Diagram of Electric 
Arc Furnace with inclined 
Electrodes. 



10 



ELECTEO-THEKMAL METHODS 




Fig. 2. — ^Diagram of Electric 
Arc Furnace with Vertical 
Electrodes. 



within the metal itself (according to Joule's law) by the resist- 
ance offered to the passage of the current through it. Since the 
temperature attained by this method of heating cannot equal 

that attained in arc heating, the 
radiation and conduction losses are 
lower, and the thermal eflficiency of 
the furnace is higher. On the other 
hand, certain refining operations that 
can be carried out with ease in the 

-y yr/j^ arc furnaces cannot be successfully 

^^^^ performed in resistance furnaces. 
The Eochling-Eodenhauser or ** Com- 
bination " furnace is the best known 
type of resistance furnace. 

The Induction furnaces form only 
a sub-division of the resistance type 
of furnace, since the thermal effect is again due to the resistance 
of the metal to the flow of the current through it. In this case, 
however, "induced" currents of electricity are used, in place 
of direct currents. An ** induced " electric current is one that 
is created in any closed conducting circuit when an alternating 
current is allowed to pass through a neighbouring (or parallel) 
circuit. The induction furnace is, in fact, nothing but a huge 

step-down transformer, in 
,^ which a ring of molten 
metal forms the secondary 
circuit and becomes the focus 
of currents of large intensity 
but low E.M.F. 

The disadvantages of this 
type of furnace are its com- 
paratively low temperature, 
and the necessity for retaining a certain proportion of every 
melt in the annular ring, in order to carry the current for 
melting the next charge. The great advantage is that 




Fig. 3. — ^Diagram of Electric Eesistance 

Furnace. 



GENERAL PRINCIPLES AND METHODS 



11 



electrodes are dispensed with, and that this costly item of the 
running charges is wiped out. A secondary advantage is that 
the capital expenditure upon cables and conductors is greatly 
reduced. 

The Kjellin and Frick furnaces are the best known examples 
of the induction type of furnace. 

Figs. 1 and 2 are diagrammatic sections of the two forms of 
arc-furnaces ; Fig. 8 is a similar section of a simple resistance 
furnace, and Fig. 4 is a diagrammatic section of a simple 
induction furnace. The core and primary circuit in Pig. 4 
are shown in the centre, the sections of the annular trough on 
each side contain the molten metal. 

The distinguishing feature of arc-heating is that a very high 
temperature effect is concen- 
trated chiefly on the surface 
of the metal, or of the slag 
covering it; whereas in re- 
sistance-heating (whether by 
direct or induced currents) a 
more moderate and uniform 
heat effect is produced within 
the body of metal contained 
within the furnace. As will be seen in the succeeding Chapters of 
this book, the different types of furnace are tending to approach 
one another in design ; for it has been found that the washing-out 
processes, by which the impurities phosphorus and sulphur are 
removed from the molten metal by means of suitable slags, can 
only be effectively and rapidly carried out with the aid of 
high temperatures. 

Turning now from the consideration of the general principles 
and features of the design of electric furnaces for iron and 
steel production to a study of particular furnaces, we find that the 
first electric furnace for steel-melting was patented by Charles 
William Siemens, of London, in the year 1879 (see British 
Patent No. 2110 of 1879). 





Fig. 4.— Diagram of Electric 
Induction Furnace. 



12 ELECTRO-THERMAL METHODS 

As this patent is of considerable interest the following extracts 
from the original Patent Specification are given : — 

" In the Specification to Letters Patent granted to me on the 22nd of 
October, 1878, No. 4208, I described the cooling of the terminal of an 
electric lamp by means of a stream of water passed through a cavity 
formed in the terminal. My present invention relates to arrangements 
in which, by the use of such water-cooled terminals, I am enabled con- 
veniently to apply the electric current to the production of light as in 
electric lamps, or of intense heat within a crucible, for the purpose of 
fusing refractory materials. 

** In applying the electric current to the production of intense heat 
for the fusion of refractory substances, I employ two carbon rods fitted 
to slide towards each other horizontally through holes in the opposite 
sides of a crucible made of highly refractory material, such as lime or 
alumina, which may be water-cased if necessary. The substance to be 
fused is introduced, into the crucible, and the carbon rods are advanced 
sufficientlv near to each other to form the voltaic arc within the crucible. 
They are, therefore, made to advance by clockwork or other suitable 
motor, each at a speed proportioned to its rate of consumption so as to 
maintain the arc always within the crucible. The clockwork which 
advances them may be retarded, arrested, or reversed by the action of 
a thin metal strip or solenoid, as in the electric lamps above described. 
As the heat in the crucible increases, the resistance to the voltaic arc 
within it diminishes, and consequently the arc can be elongated, an 
effect which results from the automatic retardation, stoppage, or reversal 
of the feeding clockwork. The crucible may be closed by a cover, 
having apertures through which air or other gases may be blown or 
drawn, to act on the substance under treatment. In some cases, 
instead of employing carbon for the terminals, they may be made of the 
material that is to be fused, when it has suflBcient conductivity." 

Figs. 5 and 6 give a diagrammatic representation of the two 
forms of crucible furnace designed by Siemens, who also demon- 
strated that with this type of furnace he could melt 10 kgs. 
of iron or steel, with comparative ease, in one hour. 

Though no industrial application of Siemens' furnace was 
made, for the simple reason that electricity was at the time 
much too expensive a form of energy to be used for heating 
purposes outside the chemist's or physicist's laboratory, yet 



GENEEAL PKINCIPLES AND METHODS 



13 




Siemens' invention was the prototype of the successful Heroult 
and Stassano furnaces which are now so widely employed in the 
steel-refining industry. 

Henri Moissan was the first chemist to apply with success, 
electric arc methods of heating in 
the laboratory, and the remarkable 
series of researches carried out, and 
of discoveries made by this famous 
French chemist, in the years 1890 — 
1895, have found a fitting record in 
his classical work " La Four Elec- 
trique," published in 1896. 

The furnace used by Moissan in 
these researches and discoveries was 
formed by two solid blocks of lime, 
fitting closely the one over the other, 
but hollowed out at the centre to form 
a small cavity, in which his high 
temperature effects were obtained. 
The arc was formed between carbon pencils or electrodes by 
aid of a low-tension electric current. 

The electric arc furnaces used for steel refining are similar 
in principle, but are constructed on 
a much larger scale. The Stassano 
type of furnace most closely resembles 
that of Moissan, for it has the elec- 
trodes arranged at an angle of 30 
degrees, and the heating effect is 
obtained by radiation from the arc 
formed above the surface of the 
metal. The Girod and Heroult furnaces are designed with 
vertical electrodes, and the molten metal itself acts as one pole, 
from which the arc springs. In these cases, therefore, there is 
actual contact between the metal, or slag, and the electric arc, and 
the heat transfer is partly by radiation and partly by conduction. 



Fig. 5. — Siemens Crucible 
Furnace. 




Fig. 6. — Siemens Crucible 
Furnace. 



14 ELECTKO-THERMAL METHODS 

As Charles William Siemens may be regarded as the originator 
of the arc type of steel-melting and refining furnaces, so may 
S. Z. de Ferranti claim to be the inventor of the induction 
type of furnace, though here again many years elapsed before 
any practical developments occurred. 

Ferranti's first patent for the induction form of furnace con- 
struction was taken out in 1887 (Patent No. 700), or thirteen years 
in advance of the first British patent granted to the Swedish 
Engineer Benedicks for a similar type of furnace. The success- 
ful furnaces of Kjellin, Frick, Hiorth, and Rochling-Eodenhauser 
are all developments or modifications of Ferranti's original 
design. 

The first successful industrial application of electric heat to 
steel-refining appears to have been made at La Praz, France, in 
1899, by M. Paul Heroult, a well-known French metallurgist. 
M. Heroult in the years 1886 — 1888 had worked out the details 
of and had patented a successful electro-metallurgical process 
for the production of aluminium, and, at the date named, he had 
already seen this process develop into the basis of a prosperous 
industry. It was therefore natural that he should attempt 
to apply the knowledge and experience gained in the period 
1888 — 1896 to other branches of metallurgical industry. An 
electric furnace for the manufacture of ferro-alloys was first 
designed, and was applied with success to the production of 
ferro-chrome, ferro-tungsten, ferro-silicon and other similar alloys. 

In 1899 and 1900 Heroult designed and put into operation at 
La Praz his first furnace for refining steel by aid of electric heat, 
and about the same date Keller, another French metallurgist (at 
Livet), and Stassano, an Italian Army Engineer (at Eome), com- 
menced similar trials with the types of electric furnace which 
they have since patented and developed. 

The next few years witnessed a great rush of activity in the 
designing of electric furnaces for the iron and steel industry. 
The Patent Office files of all countries bear witness to the 
number and fertility of inventors in this new field of applied 



GENERAL PRINCIPLES AND METHODS 15 

electro-metallurgy. For the reasons already stated in the 
previous Chapter, the majority of these inventions have failed to 
bring their patentees any credit or pecuniary reward, and the 
number of different types of electric steel-refining furnaces in 
successful operation at the present day, can be numbered on the 
fingers of one hand. 

It is the opinion of the author and of many authorities that 
future improvements and developments will occur in connection 
with details of furnace working and control, rather than in any 
alteration of the broad lines of furnace design. The improve- 
ment of electrodes and their holders, and the discovery or 
manufacture of more durable refractory materials for furnace 
linings, are the most pressing needs of the moment. 

With regard to the first of these, the cost of Electrodes is still 
a very serious item of the total refining charges, and any 
improvements that would lengthen their life or cheapen their 
first cost would prove of great benefit to the electric iron and 
steel industry. Although graphite is a better conductor than 
carbon, and electrodes of graphitised carbon are the more 
durable, ordinary carbon electrodes on account of their greater 
cheapness are employed usually for electric furnace work. 

These are made for the iron and steel furnaces up to 24 ins. 
in diameter and 72 ins. in length. A round section has been 
found to give more economical results than the square shape 
formerly used. A method of jointing carbon electrodes has also 
been introduced which avoids the formation of, and loss arising 
from, butt ends. It is quite possible, however, that some sub- 
stitute for the ordinary carbon electrodes may be found, since 
carbon has one great defect for electric furnace work, namely, 
its great afl&nity for oxygen, and the constant wasting away 
which occurs by its combination with this gas both inside and 
outside the furnace. The fact that this slow wasting away of the 
carbon, at the point where it enters the furnace roof can be 
minimised by water-cooling, does not altogether surmount the 
difl&culty, for the water-cooled carbons abstract heat from the 



16 ELECTRO-THEKMAL METHODS 

furnace. Water- cooling, though generally practised as the lesser 
of two evils, thus leads to a direct loss of heat. Furnaces of 
the Resistance type escape this problem of carbon electrodes ; 
but, as pointed out above, tliese furnaces have some difficulty in 
attaining and maintaining a temperature which permits of the 
rapid and efficient refining of impure raw materials. 

In this connection the suggestion contained in Siemens' Patent 
Specification, already quoted, that the material being fused might 
be employed as electrode material, is worthy of consideration. 
The history of the electric glow-lamp is not without interest for 
electro-metallurgists ; and if fine wires of tungsten, tantalum and 
other metals have replaced the carbon filament in glow-lamps, it 
is perhaps not indulging in a vain hope to expect and believe 
that sooner or later a solid or molten metallic conductor may be 
discovered suitable for electric furnace work. The design of the 
Girod and Chaplet furnaces indicates how carbon can be dis- 
pensed with in steel-refining for the lower electrodes of the 
furnace ; and the problem is therefore now reduced to the dis- 
covery of a metal or material suitable for the upper electrodes of 
arc furnaces. 

The use of iron or steel electrodes, alloyed with one or more of 
the rarer metals that raise the melting-point, and that would be 
required as additions to the finished steel, would seem to aflbrd 
the simplest and most practical solution of the problem. The 
writer believes that experimental trials along these lines are now 
proceeding. 

As regards the liefractonj Materials used for the hearths, 
linings, and roofs of furnaces, the magnesite and silica bricks 
used at present have not proved entirely satisfactory, and 
electric steel makers are on the look out for, and are quite pre- 
pared to give a fair trial to, any refractory material suitable for 
their purpose, that may prove more durable and can be produced 
at a reasonable cost. At the moment no satisfactory substitutes 
for tamped magnesite and tar or silica are known ; but trials 
are about to be made with electrically-fused alumina bricks, for 



GENEEAL PEINCIPLES AND METHODS 17 

which high claims are made. The roofs of arc furnaces, and the 
upper portion of the sides of resistance furnaces, are the parts 
where the most destructive action occurs ; and a refractory 
material that is to prove durable in these places must be able 
to stand the action of high temperatures, and of lime, silica and 
iron, all in the vapourised state. Whether the new ** Alundum " 
bricks will stand the combined attack of these powerful physical 
and chemical forces remains to be seen. 

As regards the question of Electricity Supply, direct current 
generators can be employed for arc and simple resistance 
furnaces, although the tendency is more and more towards the 
use of alternating current (either single-phase or three-phase) 
for electric furnace work. For the benefit of those readers who 
do not understand electrical terms, it may be stated here that a 
direct current is one in which the flow of current is constant in 
one direction only. An alternating current, on the other hand, 
is a current the direction of which is reversed at regular 
intervals ; the number of reversals per minute being indicated 
by the figure for the frequency, and the number of phases being 
expressed by the terms "single-phase," ** two-phase" and 
** three-phase." 

The construction of large dynamos is simplified, and the 
danger to the workers is considerably minimised, when 
three-phase current is generated, and as the modern tendency 
is all in the direction of large generating units, electric furnace 
designers have many sound reasons for adapting their needs to 
the requirements of the generating stations. In the majority of 
installations the iron and steel furnaces are provided with their 
own power stations, operated either by water, or by the waste- 
gases from blast-furnaces and coke-ovens. In SheflBeld and in 
a few other centres, steam-power is employed for generating the 
current required. 

Concerning the Chemistry of the Refining Process, it must be 
clearly understood that no electrolytic action occurs in the furnace, 
and that the effect of the electric current is simply of a thermal 

E.T.M. c 



18 



ELECTRO-THEEMAL METHODS 



character. The refining action is due to the washing out and 
removal of sulphur, phosphorus, etc., by the aid of suitable 
slags. As the theory of the action of the slag upon the steel is 
of great importance in its bearing on the practical results 
attained, an abstract of a recent valuable paper by Amberg 
upon this subject has been included in the Appendix (see 
p. 223). 

In concluding this general discussion of the principles of 
electric steel refining, it may be of interest to present some 
figures, showing the power required to produce one ton of steel 
from various raw materials. Table I. contains a summary of 
figures collected by the author and published in 1907 in the 
handbook already referred to.^ Table 11. contains figures 
compiled by V. Engelhardt and published in an article 
contributed to the paper named below.^ 

A comparison of these two sets of figures with each other, and 
with those 'given in the last Chapter of this volume, will indicate 
the progress that has been made in electric steel refining between 
1907 and 1912 :— 



Table I. 

Kw. hours required for the production of one ton (2,000 lbs.) of iron 

or steel, in different types of furnace (1906). 





I. 


II. 


III. 


IV. 




Heroult. 


Keller. 


Stassano. 


Girod. 


Steel from scrap and 










pig (cold) 


864 


730 


1,164 


1,136 


Steel from scrap and 










pig (hot) 


329 


631 






Pig-iron from ore, coke 










and lime (cold) 


2,693 


2,292 






Steel from ore, coke 










and lime (cold) 




2,800 


2,804 




Nickel pig from ore . 


2,342 




- 





- See Chap. I., p. 1. 

2 Zeltschr Verelnes Deutseh, Ing,^ November 19th, 1910. 



GENEKAL PRINCIPLES AND METHODS 



19 



Table 11/ 

Kw. hours necessary for the production of one ton (2,204 lbs.) of iron or 
steel, in a Rochling-Rodenhauser furnace (1910). 

Kw. hrs. 
Pig-iron direct from the ore .... 2,000 



Steel direct from the ore . 

Steel from cold pig-iron . 

Steel from liquid pig-iron 

Steel from cold pig and cold scrap . 

Steel from liquid pig and cold scrap 

Steel from cold scrap 



3,000 

1,500 

1,100 

700 

600 

900 



Refining molten open-hearth steel for special 

tool steel . . 250 

Refining molten open-hearth steel for rail steel 120 

Maintaining heat in a casting ladle ... 50 

The actual costs of production, when working under various 
conditions as regards raw materials, are given by Engelhardt for 
a 6-ton Bochling-Bodenhauser furnace as follows : — 

Steam-power. — Prom 94*5 marks to 123*3 marks per ton. 

Water-power, — From 78*6 marks to 96*1 marks. 

The cost of the former is taken at 6 pfgs. (or three-fifths of a 
penny) per kw. hour ; and of the latter at 2 pfgs. (or one farthing) 
per kw. hour. 



c ti 



CHAPTEE III 



ELECTRIC SMELTING FURNACES 



1. — Early trials at Darfo, Livet and at Sanlt Sainte Marie. 

The first experiments upon the smelting of iron ores in 
electric furnaces were made by an Italian, Captain Stassano, in 

the years 1899—1901, at 
Borne, and later at Darfo, in 
Northern Italy, where cheap 
power was available. The 
furnace used was of the arc 
type (Fig. 7), still employed 
by Stassano for electric steel 
refining, with three-phase 
current and water-cooled 
electrodes. The ore was 
first finely ground, and after 
mixing with the lime and 
coke was briquetted, before 
charging into the furnace. Any practical metallurgist could have 
foretold that the cost of this preliminary treatment of the ore 
would render the method expensive and impracticable. Although 
the trials at Darfo did not result in any financial success, they 
proved that steel of good quality could be produced in this way 
direct from the ore, and Goldschmidt, who made an official report 
upon the method for the German Patent OflBce, gave the following 
figures for the power consumption and cost of operating the 
process : power, 2,866 kw. hours per metric ton of steel ; cost, 
£4: 9s. per ton (power at £1 Ids. per e.h.p. year), and ore at 
12«. per ton. 




Fig. 7.— Stassano Arc Furnace 
(earliest type). 



ELECTRIC SMELTING FURNACES 21 

The next InveBtigstor of the subject was Keller, a French 
electro-metallurgist, who carried out extended trials with an 
electric furnace of bis 
own design for ore re- 
duction, at £errousse, 
and at Livet, in France, 
in the years 1901—1905. 
It was at the latter place, 
that the Canadian Com- 
mission upon electric 
furnace methods of iron 
smelting, carried out 
their trials in March, 
1904. The furnace used 
for these trials was a 
double abaft - furnace 
(Fig. 8), connected by 
a lateral canal, which, 
when the furnace was 
operating, became filled 
with molten iron reduced 
from the charge of ore 
in the two shafts. 

Composite massive 
carbon electrodes, 
84 ins. square and 
56 ins. in length, were 
used with this furnace. 
The raw materials wjie 
roughly crushed and 
mixed, before charging 

into the shafts. The Fm.S.— ^ller Shaft Furnace. 

experimental trials 

made at Livet yielded the folloning mean results: power, 
2,292 kw. hours per ton (*2,000 lbs.) of pig iron ; cost, £2 8s. 



23 EtECTftO-TfiERMAL METHODS 

per ton of pig-iron, with power at 41«. 8^. per e.h.p. year, and 
ore at 68. Od, per ton. 

After these early trials of the electric furnace for iron smelt- 
ing, nothing more was done until 1905 — 1906, when HerouU, the 
noted French metallurgiet, arranged that his own type of shaft 
furnace should receive trial at Saulte Sainte Marie, in Canada, 
under the auspices of the 
Canadian Government. The 
furnace used in these trials was 
a square shaft furnace of a much 



Pig. 9.— No. I Ileroiilt 
Shaft Furnace (early Fig. 10.— No. 2 Heroult Shaft 

tn>^)- Furnace (Canadian tj'pe). 

simpler design and construction than those used by Stassano and 
Keller. Fig. 9 shows Heroult's original design for an iron ore 
smelting furnace and Fig. 10 the furnace actually employed at 
Sault Sainte Marie. The iron bottom plate of the latter furnace, 
24 ins. square, served as one electrode ; the other was a carbon 
rod, 16 ins. square by 72 ins. long. As raw materials, the 
native magnetic iron ore of the district, with charcoal in place of 



ELECTKIC SMELTING FUENACES 23 

coke, were used. Although the method and process were found 
to be feasible from the scientific point of view, the commercial 
prospects were less satisfactory, and the project of establishing 
an electric smelting industry on the Canadian side of the Great 
Lakes was reluctantly abandoned by its supporters. 

The estimated power consumption, based on Dr. Haanel's 
trials at the Soo, with the Heroult furnace for a large 10,000 h.p. 
plant, was 1,000 e.h.p. days per 12 tons of pig, equivalent to 
1,470 kw. hours per ton. The estimated cost for Canadian con- 
ditions of labour, ore and power supply, was $10*69 per ton of 
2,000 lbs. (£2 4«. 6d.). In this estimate, ore was. taken at 
$1'50 per ton ; charcoal at $6*00 per ton ; and electric energy at 
•165 cent per kw. hour, or $10*71 per e.h.p. year (£2 4s. Id.). 

2. — Recent Trials. 

(a) The Trials at Ludvika and Domnarfvet in Sweden. 

The success, from the scientific standpoint, of these early trials 
with electric iron smelting furnaces led three Swedish engineers, 
Messrs. Gronwall, Lindblad and Stralhane, to undertake further 
trials of this method of iron smelting in Sweden in the years 
1906 — 1907. The special aim of these inventors was to design.an 
electric smelting furnace which should prove commercially 
successful, when operated with Swedish ore and under Swedish 
conditions of power and labour supply. In carrying out their 
plans for this work they were greatly assisted by a group of 
Swedish iron masters, who not only provided technical facilities, 
but also assisted the three engineers in obtaining the necessary 
funds for the experimental work. The first furnace, of 300 h.p., 
was ready for operation in April, 1907, and a second one, with the 
improvements based on the experience gained in operating the 
first, was erected during 1908. The following description of 
the latter furnace is taken from Dr. Haanel's report, prepared 
for the Canadian Government and published in 1909. 



24 ELECTfiO-THEEMAL METHODS 

In general appearance tine electric shaft furnace is unlike any 
hitherto constructed ; being very similar in design to an ordinary 
blast furnace, in which the tuyeres are replaced by electrodes. 
[A vertical section of the furnace is represented by Fig, 11.] 
The height above ground level was about 25 ft. The melting 
chamber or crucible containing the electrodes was about 7 ft. high, and 
was of greater diameter than any other part. The shaft was about 
18 ft. high ; the lower end for about 4 ft. had the form of a 
truncated cone. The purpose of this design was to direct tlie charge 
into the crucible in such a 
manner that the electrodes, 
lining and descending charge 
should not come into contact. 

This special feature of the 
design was introduced by the 
inventors after repeated experi- 
ments, and it is this isolation of 
the descending charge from the 
lining, at the point where the 
electrodes enter the furnace, 
that constitutes the particular 
economic advantage of the 
Gronwall design of furnace 
construction, since it tends to 
prevent the destruction of the 

For the purpose of cooling 
the brickwork used for lining 
the roof of the melting chamber, 
and thereby increasing its life, 
three tuyeres were introduced 
into the crucible {just above the 
melting zone), through which the comparatively cool tunnel-head gases 
were forced against the lining of the roof. These gases absorbed heat 
from the exposed lining of the roof and walls, and from the free 
sur&ce of the spreading charge, thus effectively lowering the 
temperature. 

Each electrode was built up from two carbons 11 ins. square and 
63 ins. long, making the total cross section of the composite electrodes 
11 ius. by 22 ins. 

The water-cooled stuffing boxes, through which the electrodes entered 
the melting chamber, were provided with special devices (not shown lu 



ELECTRIC SMELTING FURNACES 25 

tlie drawing) for preventing leakage of the gas under pressure within 
the melting chamber. 



Fro. 12, — No, 2 Gronwall Furnace at Domnartvet [external view). 

Haanel carried out with this fnrQace a seriea of trial tests on 
December 27th, 28th, and 29th, 1908, the more important 
results of which are given below. 

The ore nsed was Magnetite from the Grangesberg District, 



26 ELECTEO-THERMAL METHODS 

containing 68 per cent, metallic iron, 3"16 per cent, of silica and 
2*34 per cent, phosphoric acid. Although the furnace was 
designed for a larger output, the low water supply would only 
admit of a power consumption during the trials of 400 — 450 kw. 
As regards yield, the average of nine tappings gave 1'87 tons pig- 
iron per e.h.p. year, but owing to the heat losses, due to heating 
up the furnace, and to an accident to one of the stuffing boxes, a 
yield of 2'44 tons obtained at the sixth cast was taken as the 
most reliable figure for the yield. This is equivalent to 2,675 kw. 
hours per ton (2,204 lbs.) of pig. It was believed however, that 
under more favourable conditions of work the power consumption 
could be reduced to less than 2,000 kw. hours per ton of pig, and 
Professor Von Odelstiern, of Stockholm, made the following 
estimate for a furnace producing 8,000 to 10,000 tons of pig-iron 
per annum : — 



■J 


s. . 


rf. 


Charcoal, '27 ton at 33«. 4d. per ton 


9 





Power, "30 e.h.p. year at 50«. 


15 





Tjabour . 


4 


2 


Electrodes, 10 lbs. at l^d. per lb. . 


1 


3 


Eepairs, etc 


6 


3 



£1 15 8 



This estimate did not, it must be noted, allow anything for 
the cost of ore, or for interest and depreciation of plant and 
machinery. 

Following up the success attained with this smelting furnace 
at Domnarfvet, arrangements were made with the TroUhatten 
Water Power Co., to erect a larger plant at TroUhatten, the 
following being details of the scheme : — 

Each furnace was to be of 2,500 h.p. capacity, and to produce 
7,500 tons pig-iron per annum. Two furnaces were to be kept 
in operation and one in reserve. The ore used was to be 
Magnetite from Grangesberg, and to contain between '40 per cent, 
and 1*9 phosphorus. 



ELECTRIC SMELTING FtJKNACES 27 

WeBtphalian eoke was to be used, costing 23s. 7d. at Troll- 
batten. Power was to be supplied at 31s. per h.p. year, rising 
to ils. id. after ten years. The estimated capital required for 
financing the undertaking was £32,400, and the estimated cost 
of pig-iron 57s. id. per ton, leaving a margin between producing 
and selling price of 78. lOd. per ton. The Swedish Association 
of Ironmasters provided 
the necessary capital, 
and the erection of one 
portion of the new plant 
was completed towards 
the end of 1910, at a 
cost of ;£17,700. The 
furnaces follow in tbeir 
main lines of construc- 
tion that erected at 
Lomnarfvet, but they 
are much larger, and 
have four electrodes in 
place of three. Figs- 13 
and 14 show a sectional 
elevation and external 
view of one furnace. 
The gases passing 

from the top of the s«(™-«s, 

, , , Fio, 13.— No. 3 Qronwall Furnace at 

furnace are trapped, Trollhatten (vertical section). 

and are then blown by 

means of a fan into the crucible. This double circulation 
of the gases has two objects : (a) to increase the heat of the 
charge of ore and coke in the shaft above, and to render it 
more ready for the reduction process, and (b) to cool the roof 
of the furnace and to lessen the danger of overheating and 
collapse. 

The electric power for this plant is obtained from the 
Swedish Government Electric Power Station at Trollhatten, 



28 ELECTEO-THERMAL METHODS 

and is obtained in the form of three-phase cnrrent, at 10,000 volts 
pressure, and 25 cycle?. The furnace transformers are each 
1,100 kw. capacity, -with a guaranteed overload capacity up to 
1,375 kw. 



Fia. 14.— No. 3 Gronwall Furnace at Trollhatten (external view 
looking towaida tap-hole). 

Charcoal has replaced coke as the redncing agent for these 
furnaces, the average composition of this charcoal being 
moisture, 14'58 per cent., aish, 3*06 per cent., fixed carbon, 
72*10 per cent., and volatile matter, 10*26 per cent. The 
molten metal is tapped as in ordinary blast-furnace practice. 



ELECTRIC SMELTING FUENACES 29 

about 5 tons of pig-iron being obtained at each tapping of the 
furnace. 

Later Trollhdtten Operations. 

Over 3,000 tons of pig-iron have been produced at TroU- 
hatten since the first furnaces were started in November, 
1910, and the metal is stated to be of exceptionally good 
quality, containing only small percentages of sulphur and 
phosphorus. 

The following additional details of the work of the first 
TroUhatten furnace from August, 1911, to March, 1912, were 
contributed by Messrs. Leflfler and Nystrom to a meeting of the 
Swedish Ironmasters at Stockholm in May, 1912 (see MetalL 
and Chem. Engineering, July, 1912). During the summer of 1911, 
the furnace was closed down for alterations and repairs, costing 
£3,160, The four square electrodes were exchanged for six 
round ones, and a new gas circulation system was installed for 
the better drying of the gas returned to the furnace. The cooler 
acts on the condenser system, and requires 100 litres of water 
per minute to reduce the temperature of the gas, so that its 
moisture content is reduced from 4 gms. per cubic meter to 
0*5 gm. All the electric pig-iron furnaces now being built and 
operated in Sweden and Norway are provided with this 
condenser, in order to avoid returning moisture to the smelting 
zone of the furnace. The round form of electrode was used 
(with screwed and tapped ends) in order to avoid formation of 
butts. The dimensions at first were 22 ins. X 60 ins., and 
later were increased to 24 ins. X 72 ins. For the 216 days 
which the furnace was run during the above period, the 
average net consumption of electrodes was 6*18 kgs. per ton of 
pig-iron produced, or '618 per cent, of the iron. It is hoped that 
as the efficiency of the furnace is improved this consumption of 
electrodes may be reduced to 4 kgs. per ton. The smaller 
electrodes 'vere manufactured by the Planiawerke, at Eatibor ; the 
larger ones by Messrs. Siemens and Halske, at Lichtenberg. As 



80 ELECTRO-THERMAL METHODS 

regards ore used, various hsematites and magnetites were 
employed, varying in composition as follows : — 

Iron . . 42'00 per cent, up to 68'96 per cent. 
Silica . . 3-42 „ „ 28-46 



Sulphur . . -001 „ „ -ISB 

Phosphorus . '002 „ „ -056 



99 



The method of restarting the furnace was as follows : — 
Half a ton of scrap-iron and ^ ton of limestone were put on 
the hearth ; on this was placed one ton of dry coke ; over this a 
mixture of 3 tons of castings, 1*2 tons of coke, and 8^ cwts. of 
limestone. This filled the crucible up to the electrodes. 
Eight cwts. of broken electrodes were then scattered on top to 
give electrical connection between the electrodes. On the top of 
this were placed regular charges of ore, fuel and limestone. 
According to Richards (see issue of Metall, and Chem. 
Engineering for July, 1912), the best figures were obtained in 
September, 1911, when a yield of 4 tons of iron per e.h.p. year 
was averaged over a period of one week. 

It is expected, however, that an output of 5 tons per e.h.p. 
year will be obtained with larger furnaces and more efficient 
control of the electrical reduction process. The metal produced 
in this furnace is really pig-steel, since it contains 97 — 
98 per cent, iron and only 2 — 3 per cent, impurities. 
This improvement in the composition of the metal has 
followed the cutting down of the coke supply of the furnace to 
the minimum required for reducing the oxide of the iron ore to 
the metallic state. It has been discovered that the electric iron 
furnace, worked under these conditions, has an increased output 
of a purer metal than when worked as formerly, with an excess 
of coke. The steel refining furnace also is found to produce 
more steel, and at a less "cost, when supplied with the product of 
the electric iron furnace than when using ordinary pig-iron, 
and this discovery has been the most notable reason for the 
success of the new Swedish Electric Iron Industry. The 



ELECTRIC SMELTING FURNACES 



31 



following figures show the best average so far, for one month's 
continuous work (September, 1911) of the TroUhatten furnace : — 



Table m. 

Pig-iron produced, tons . 

Quantity of slag, tons 

Iron in the ore, per cent. 

Iron in the ore and lime, per cent. . 

Quantity of slag per ton of iron, kgs. 

Charcoal used per ton of iron, kgs. 

Average load, kw 

Average power, h.p. 
^ Current used per ton of iron, kw. hours 
^ Iron produced per kw. year, tons . 
Iron produced per h.p. year, tons . 
Average CO2 contents in gas, per cent. 

C per cent. 

Si 

Mn 

S 

P 



>> 



>) 



ti 



>> 



>> 



99 



637-9 
88-9 
67-65 
66 02 
166 
839-9 
1,407 
1,913-5 
1,749 
601 
3-68 
29-27 
3-64 
0-36 
0-40 
0-009 
0-018 



Since the furnace was restarted, there has been considerable 
variation in the results obtained, owing to the trials that have 
been made with different kinds of ore and with different 
proportions of concentrates. 

The above figures, however, are typical of the results obtained, 
under regular and normal conditions of work. 

Four large electric pig-iron furnaces of similar design were 
expected to be in commercial operation in Scandinavia early in 
1912, located at Domnarfvefc and Hagfars, Sweden, and at 
Tyassaa, Norway. The largest of these is at Tyassaa and has 
a power capacity of 3,600 kw. 



^ According to instruments at the furnace. 

' f)stimated on the basis of 8,760 kw. hours per kw. year. 



82 ELECTRO-THERMAL METHODS 

In concluding this review of the present position of electric 
iron ore smelting in Sweden, it may be pointed out again that 
the conditions in that country and in Norway, for the successful 
development of the process, are probably more favourable than 
in any other part of the world. 

High grade iron ore is abundant, and electric power developed 
from large waterfalls, is remarkably cheap. The country has no 
deposits of coal and the native iron industry has been dependent, 
therefore, on charcoal made by carbonisation of the timber, with 
which the lower sides of the valleys and mountains are covered. 
To replace two-thirds of the charcoal required by the ordinary 
process of iron smelting by electric power is therefore a most 
profitable substitution. 

The future of the electric iron smelting industry in Scandi- 
navia ought therefore to be assured, and its gradual development 
will be of enormous importance to the industrial progress of 
Sweden and Norway. 

(b) The Trials at Heroult, Shasta County, Califomia. 

The only other locality where, at present, similar conditions 
prevail is California. No coal beds are known to exist in this 
strip of the western border of the United States, and the selling 
price of pig-iron and steel is very high, due to the heavy freight 
charges from the Eastern States and from other centres of the 
iron and steel-making industry. For this reason, the further 
trials of the Heroult iron smelting furnace and process in 
America were transferred from the ** Soo *' to Shasta County, 
California, where a cheap and plentiful supply of power was 
combined with the other requisite conditions for the development 
of a successful electric iron smelting industry. 

The trials at Heroult, on the Pitt River, Califomia, were 
initiated by Mr. H. Noble, President of the Northern California 
Power Co., who was anxious to find an outlet for some of the 
surplus power produced by their generating plant. M. Heroult 
was therefore retained by Mr. Noble early in the year 1907 to 



ELECTRIC SMELTING FUENACES 38 

design and erect a furnace for smelting the iron ore produced by 
the Shasta Iron Co. at that place. 

The following deBcription of the furnace, as erected, was given 
by R. L. Phelps, in an article contributed to The Mining and 
Scientific PrenH, July 20, 1907. 

The smelter itself was elliptical in form, with one compart- 
ment, standing about 5 ft. high, made of heavy sheet-steel 
and lined inside with the best magnesite brick. The bottom of 



Fig. 15.— No. 3 Heroult Furnace, at Shasta, California. 

the furnace was formed of heavy cast-iron plates, with a covering 
of tamped carbon to form the neutral point of the circuit. The 
bottom plates were insulated from the upper parts of the furnace 
with asbestos. 

A tap and trough were provided on one side to draw the 
molten pig-iron on to the moulding beds. Through apertures 
in the top cover of the furnace the three carbon electrodes 
were introduced. These carbons were 18 by 18 by 72 ins. 
and were made in Sweden. They were fastened by wedges to 
a copper holder, which was water-jacketed, and by mechanical 

B.T.M. D 



84 ELECTEO-THERMAL METHODS 

means were lowered and raised from the furnace when 
necessary. Four combination charging and draft tubes were 
placed on the top cover of the furnace. The tubes consisted 
of an inner tube made of steel and an outer tube made of cast- 
iron, so as to leave an annular space large enough to serve as a 
conduit for the gases that were generated. Bunsen burner slots 
were provided in the base of each tube to allow enough oxygen 
to enter, in order to complete the combustion of the gases 
liberated from the charge. The burning of these gases in the 
annular space heated the charge as it was fed through the inner 
tube to the furnace, thus delivering the charge hot instead of 
cold. The furnace was designed to utilise 1,500 kw. in the form 
of three-phase current at 50 volts and 60 cycles. 

The charge was composed of charcoal, limestone and ore. 
The charcoal was burned in kilns close to the plant. The heat 
for smelting the ore was obtained from the resistance of the 
slag and charge to the current as it passed from the electrodes 
to the neutral point ; consequently, at the start, the electrodes 
were in slight contact with the neutral bottom of the furnace. 
As the charge became heated the electrodes were drawn out of 
the molten iron and remained in the slag and charge. 

Fig. 15 shows a sectional elevation of the furnace. 

The cost of the ore was estimated at 6s. Sd. per ton, and of 
power 50«. per e.h.p. year, with charcoal at less than 4s. 6d, per 
ton. 

It was estimated, therefore, that it would be possible to produce 
pig-iron at a cost of 67s. Sd. per ton or under, assuming that 
1 ton could be produced with an expenditure of 2,700 kw. hours. 

This furnace was first put into operation on July 4, 1907, and 
it was hoped that a production of 24 tons per day would be 
speedily attained. For various reasons these expectations were 
not fulfilled, and the output never exceeded 11 tons of pig-iron 
per day. 

According to Elwell, it was found impossible to run the furnace 
for any length of time, as the electrodes were exposed to the air 



ELECTEIC SMELTING FUENACES 



85 



and were consumed rapidly, and the heat from the open furnace 
top was so unbearable that the men refused to work. The 
experience gained in this first trial, however, was utilised in the 
plans for a second furnace, which was erected to the designs 
of Professor Dorsey Lyon, of Stanford University. The new 
furnace was smaller than the first, being of 160 kw. capacity. 




Fig. 16. — No. 1 Lyon Heroult Furnace, at Shasta, California. 

and was designed to run with 4,000 amperes at 85 volts single- 
phase current. The furnace stack was built of concrete and was 
29 ft. in height. The crucible was lined with firebrick, and was 
water-cooled, the electrodes being fixed in its walls. The charge 
of ore, lime and charcoal was preheated in the stack before 
reaching the zone of fusion in the crucible between the two 
electrodes, which were fixed 24 ins. apart. The new furnace was 

d2 



86 ELBCTKO-THERMAL METHODS 

heated up early in 1908, and was run experimentally for a period 
of forty days, the lowest figure obtained in the trial runs being 
8,066 kw. hours per ton of pig. The output of the furnace 
was 2,400 lbs. per day 
of twenty-four hours. 
It was hoped to reduce 
this power consumption 
with a larger furnace 
capable of longer con- 
tinuous runs, and plana 
for a 1,500 kw. furnace 
of similar design, but 
■ to employ three-phase 
current, were next pre- 
pared. 

Fig. 16 shows a sec- 
tional elevation and 
Fig. 17 a general view 
of the exterior of the 
1,500 kw. furnace ulti- 
mately erected, and put 
into operation in the 
autumn of 1909. The 
following description of 
the working of the fur- 
nace is taken from a paper 
Fig. n,~No. I Lyon Heroult Purnace: read by Professor Lyon 
(1,600 k,.), .t Sh..t., Calitok. |^,„,^ ^^^ ^j^g^^^ j,^„, 

meeting of the American Electrochemical Society in that year : 
In the operation of the furnace the ore, with its proper proportion of 
flusing materials, is fed into a preheater (b) wherein it is dried and heated. 
The heat for the preheater is derived from the products of combustion 
from the combustion chamber (k) at the top of the stack, which is let 
into the base of the preheater through a flue (e). This communicates 
with an amiular chamber surrounding the top of the stack, and with 
the production chamber through openings or ducts (1). 



ELECTRIC SMELTING FURNACES 37 

A scale car (g) runs upon a circular track round the top of the 
stack, and alternately receives a charge of ore and flux from the pre- 
heater (b) and a weighed charge of carbon from the carbon hopper (c), 
these charges being delivered alternately by proper mechanism into 
the body of the furnace. 

In the operation of the charging device a charge of ore and flux 
is first dropped into the upper portion of the hopper, the bell (h) 
being closed, and after the charge is properly distributed about the 
hopper the bell (h) is lowered so as to permit the charge to pass into 
the lower compartment of the hopper, the upper bell being then closed 
and the lower bell (j) opened, so as to permit the charge to pass into 
the stack. The charge of carbon is then fed into the furnace through 
the charging device in the same way. 

The electrodes, six in number, are arranged equidistantly around the 
furnace. The electric current passing through the ore lying between 
them melts the charge, and the molten metal and slag are collected in 
the crucible, from which they are drawn as in ordinary blast-furnace 
work. 

On July 21, 1910, a party of American steel-makers and 
engineers visited the plant of the Noble Electric Co., at Heroult, 
and witnessed this furnace in operation. The furnace at that 
date had been running without a hitch for some time, and had 
produced several hundred tons of pig-iron, but no figures were 
given to the visitors for the power consumption per ton of pig. 

The furnace was tapped every six hours and produced 5 tons 
of iron at each tapping, or 20 tons per day. A wood carbonising 
plant had been erected in close vicinity to the smelter, and wood 
alcohol, acetic acid, tar and creosote oils, were being obtained as 
by-products of the charcoal manufacture. The operation of the 
1,500 kw. furnace had proved so successful that the erection of 
five more furnaces of similar design at a cost of ^662,500 had 
been decided on, and the progress of the trials from the ex- 
perimental to the commercial stage was considered to have 
commenced. Since that date but little information has been 
published concerning the progress of this Smelting Works at 
Heroult. One of the difficulties that this plant has had to 
contend with is the shortness of water supply during the summer 
and autumn months of the year, and the consequent inability of 



88 ELECTRO-THERMAL METHODS 

the Northern Californian Power Co. to supply suflScient power to 
run the Smelting Works continually. According to the estimate 
made by Mr. McBennie, before the larger furnace was started 
up, the cost of production was expected to be in the neighbour- 
hood of 62«. 6rf. per ton. Freight charges to San Francisco were 
expected to add about 12s. 6d. per ton to the cost of the pig-iron 
delivered at the foundries in that city. As pig was selling at 
that date at San Francisco at 96a. to 108s. per ton, the margin 
for profit and incidental expenses appeared to be sufficient to 
assure the success of the electric iron-smelting industry on the 
Pacific coast. 

As already stated, detailed figures for the output of these 
furnaces (similar to those given for the TroUhatten furnace) have 
not so far been published, and the cost of running the smelting 
plant at Heroult, California, is only known to the officials of the 
Company. Assuming that four of the six furnaces are now 
operating continuously, with two laid off for repairs, the output 
of pig should be 80 tons per day of twenty-four hours, or 500 
tons per week. 

D. A. Lyon and F. C. Langenberg have published recently 
{MetalL d Chem. Engineering, August 1912), an investigation 
of the pig-iron produced by the Noble Electric Steel Co. at 
Heroult, which proves that this metal is practically free from 
phosphorus, sulphur and manganese, and is, therefore, eminently 
suitable for use by the foundry workers on the Pacific coast of 
U.S.A. The following is their analysis of this pig-iron : — 

Silicon 3*64 per cent. Combined Carbon nil. 

Sulphur nil. Total Carbon 8*58 per cent. 

Phosphorus '02 per cent. Manganese nil. 

(c) Other Eeduction Furnaces. — The Frick and Chaplet Furnaces. 

With regard to other types of electric furnaces that have been 
designed for the smelting of iron ore, only two demand notice : — 
The Frick and the Chaplet Reduction Furnaces. Fig. 18 
shows a Frick furnace, in sectional elevation, designed to utilise 



ELECTRIC SMELTING FURNACES 39 

2,000 kw, and to prodace 26 tons of pig-iron per day of twenty- 
four hours. Although a deecription of this furnace was published 
by E. Haanel in 1910 (Bulletin 3, Canadian Department of 
Mines), with detailed figares of the power consumption and 



Fio. 18.— Prick Bedaction Furnace (aectional elevation). 

working costs, the Frick furnace does not appear to have been 
operated upon a commercial scale. Its chief interest now lies 
in its relation to the more successfully operating furnaces in 
Sweden and California. It may be pointed out, however, that 
the Frick Smelting Furnace consisted of the following parts ; — 



40 ELECTEO-THERMAL METHODS 

(1) A wide circular reaction and melting chamber, covered 
with a vault-like roof. (2) One central feeding shaft, into which 
the ore and one portion of the reduction coal were fed,, in a manner 
similar to that used for an ordinary blast-furnace. (3) Two or 
more smaller shafts, for the introduction of the electrodes. These 
latter shafts were provided with openings, through which the 
other portions of the reducing agents, coke or charcoal, were fed. 
The Frick Smelting Furnace also provided for the return of a 
portion of the waste gases to the smelting chamber of the furnace, 
an idea which is said to have originated with Harmet and to have 
been supported in 1905 by Frick. In many of its leading features, 
therefore, the Frick furnace was the prototype of the larger 
furnaces, now operating at TroUhatten and at Heroult. The 
theoretical power consumption, according to the calculations of 
Frick, lies between 1,300 and 1,650 kw. hours and the practical 
power consumption between 1,743 and 2,020 kw. hours per ton 
of pig, according to the purity and dryness of the mixing materials 
used. It is assumed in these calculations that an ore containing 
57 per cent. Fe is used as raw material. 

The Chaplet Furnace has been operated by the French company 
la Neo-Metallurgie at their steel works at d' Allevard, Isere. The 
furnace is of the arc type, and the current enters through one or 
more vertical electrodes, and leaves through one or more side 
channels ; these are connected with the main bath by horizontal 
channels below the level of the bath. The slag is charged first, 
then the ore to be reduced, mixed with carbon in proper pro- 
portions. The reduction commences under the action of the arc, 
the reduced metal filters through the slag and collects on the 
bottom. The furnace works in a similar manner to a small blast- 
furnace, in which there is also a separate reducing and fusion zone. 
The slag contains in normal operation, less than 8 per cent, iron 
oxide. The charge used is a mixture of haematite ore and dried 
powdered charcoal. Dried haematite briquettes and wood charcoal, 
and mixtures of carbon and haematite in the form of powdered 
dust, also have been tried. 



ELECTRIC SMELTING FURNACES 



41 



Further details of this furnace, which has received trial only in 
France, will be found in an article by G. Arnou (see the Revm 
de Metallurgies December, 1910.) 

3. — Comparative Yields and Costs. 

Taking the figures given in the course of this chapter, and 
bringing them to a common basis of comparison, we have the 
following table of comparative yields and costs, the power con- 
sumption being expressed as kw. hours, and the cost in £ s. d. per 
ton of 2,204 lbs. of pig-iron produced. 

Table IV. 



Process and 
Furnace. 



Stassano . 



Keller . 
Heroult . 



Gronwall 



Gronwall 



Heroult . 



Locality. 


Power. 
Kw. hrs. 


Estimated 
cost. 


Darfo . 


2,866 


£ «. d, 
3 15 


Livet . 
Sault Sainte 
Marie. 


2,589 
1,620 


2 13 
2 9 


Domnarf vet . 


1,957 


2 4 3 


Trollhatten . 


1,735 


2 17 4 


Shasta Co., 
California. 




3 2 6 



Remarks. 



Power at £1 16«. 6c?. per 
e.p.li. year. Steel pro- 
duced not pig-iron. 

Power at £2 4«. 7rf. per 

e.p.h. year. Ore 6«. per 

ton. 
Estimate based on early 

trials. Power at 50«. per 

e.li.p. year. 
Actual results obtained at 

Trollhatten, Sept. 3rd, 

1911. 
Power at 50«. per e.p.h. 

year. Ore at 6». 3d per 

ton. 



Comparing the latest figures for power consumption with those 
obtained by Stassano and Keller in the early trials, a notable 
reduction of 33 per cent, is observed, and it is quite possible that 
with larger furnaces, and with further reduction of radiation and 
other avoidable heat losses, the power consumption may ultimately 
be brought down to 1,500 kw. hours per ton of pig-iron. The 
attempts made at Trollhatten to obtain a better utilisation of the 
reducing power of the carbon, by returning the gases which pass 



42 ELECTEO-THEEMAL METHODS 

from the top of the shaft into the melting and reducing zone of 
the furnace, have resulted in an increase of the CO2 percentage 
to over 29 per cent., and it may no doubt be possible to still 
further utilise the reducing power of the carbon monoxide gas, 
which still escapes with the exit gases. But even when the power 
consumption has been reduced to 1,500 kw. hours per ton the 
electric iron smelting furnace will still be unable to compete with 
the ordinary blast-furnace methods of producing pig-iron, except 
under the most favourable conditions, as at Trolihatten and at 
Heroult. As pointed out in the introductory extract, from the 
author's book of 1907, the modern blast-furnace, when worked 
under the best conditions, only requires 16 cwts. of 6oke per ton of 
pig, and of this total 6 J cwts. are required to reduce the ore to the 
metallic state. This amount of charcoal or coke has to be pro- 
vided for by either process. The saving in coke by the adoption 
of electric heating can therefore only amount to 9*5 cwts. per ton 
of pig; costing at the present market price, in localities near the 
coal mines, 8s. 4i. to 10s. 5d. Now, if 1,500 kw. hours can be 
obtained for 10s. 5d. it signifies that the e.h.p. year must be sold 
for between 33s. 6d. and 41s. 8d., and there are, as already stated, 
exceptionally few hydro-electric stations that can produce or sell 
electric power at this figure. The electric process is also further 
handicapped by the cost of the carbon electrodes, an item of 
expenditure which has no counterpart in the ordinary blast- 
furnace procedure. 

Though the electric iron smelting processes may therefore make 
headway in those localities, where all the conditions favour their 
development, and where the price of ordinary pig-iron is artificially 
increased by freight charges — they are unlikely to undergo exten- 
sion or development, in other lands or localities, so long as cheap 
supplies of coal and coke are available for the ordinary blast- 
furnace process of manufacture. 



CHAPTER IV 

THE HEBOULT ELEOTRIO STEEL REFINING FURNACE 

The Heroult Electric Steel Refining Furnace now heads the 
list of electric furnaces in use in the Iron and Steel Industry, for 
thirty-one furnaces with an aggregate capacity of 133 metric tons 
per charge, have already been installed ; and twenty additional 
furnaces with an aggregate capacity of 143 tons per charge, are 
in course of erection. The increase in the size of the furnaces 
is clearly brought out by these totals, since the thirty-one furnaces 
in active operation have an average capacity of 4*3 tons per charge, 
while the twenty furnaces now being erected have an average 
capacity of 7*1 tons per charge. 

The largest furnaces now working are the 15-ton furnaces of the 
United States Steel Corporation, at Worcester, U.S.A., and South 
Chicago. The largest furnaces in course of erection are in Ger- 
many. A furnace of 25 tons was also in 1912 being constructed 
for use in the Deutcher Kaiser Steel Works at Briickhausen ; 
and one of 22 tons for the Steel Works at Rombach. The 25-ton 
furnace is to be operated with molten steel from a Martin open- 
hearth furnace, and presumably is to be employed for the 
manufacture of special qualities of rail or constructional steel. 

The furnaces which are working on cold scrap yield on the 
average four heats per day of twenty-four hours ; those taking 
molten metal yield fifteen heats per day. The daily aggregate 
output of the thirty-one furnaces in active operation on this 
basis is 1,489 tons per day of twenty-four hours, a total which 
will be more than doubled when the furnaces now in course of 
erection are placed in service. 

A complete list of the Heroult Furnaces in operation or in 
course of erection in January, 1912, is given in the Appendix. 



44 



ELECTEO-THERMAL METHODS 



The design of .the Heroult Furnace has undergone little altera- 
tion during the twelve years that have elapsed since the first 
English Patent was taken out, in 1900. This fact proves that 
Heroult's earlier experience in the manufacture of Aluminium 
and Ferro-alloys by aid of electric heat had been of service to 
him wheij the time arrived to design a furnace suited to the 




Fig. 19. — Heroult 3,000-kg. Furnace (early design). 

special requirements of the steel industry. A paper read by 
Turnbull before the Niagara Falls Meeting of the American 
Electrochemical Company in 1909 contains interesting details of 
the gradual developments of the Heroult electric steel refining 
furnace (see Transactions, Vol. XV., p. 189). Figs. 19 and 20 
show the original 3,000-kg. furnace with which the first trials 
were made at La Praz in 1899-1900; and Figs. 21 and 22 show 



HEROULT ELECTRIC STEEL REFINING FURNACE 45 

the 2,500-kg. furnace which was Btarted in January, 1911, at 
Braintree, in Eseex, for Messre. Lake & ElUott. The changeB in 



;n are slight and are hardly noticeable ; the most striking 
; the change from square to round electrodes, and the loca- 



46 ELECTEO-THEEMAL METHODS 

tion of the charging door at the back, instead of at the side 
of the furnace. 



General SeBorlption of the Heronlt Fnmace. 

The Heroult electric steel refining furnace coneistB of a closed 
lallow iron tank, thickly lined with refractory materials, mounted 



Fia. 21.— Heroult 2,oOO-kg. Furnace 
(latest deeigu). 

upon curved and toothed bars, which allow of the furnace being 
tilted and held by a rack at any angle for discharging purpoeee. 
Dolomite brick and crushed dolomite form the lining for the 
bottom of the furnace, and for those portions of the sides below 
the level of the metal ; while magnesite brick and crushed magne- 
site are employed for the openings, and for the portions of the 
furnace exposed to the corroding action of the slags. The top of 
the furnace is built up of silica brick, as it is this portion which 



HEEOULT ELECTRIC STEEL REFINING FURNACE 47 

saffere the most from the high temperature of the furnace 
operations. 

Afl regards the source of heat, the earlier furnaces, of S,000 kgs. 
capacity, were operated with direct current, two massive carbon 
electrodes, 65 ins. in length and 14 ins. square, well insulated 
from each other and from the furnace cover, being employed to 
carry the current into and away from the slag, resting on the 
charge of metal in the 
furnace. The carbons 
were supported by an 
insulated framework 
fixed to the back of the 
furnace, and could be 
moved either in a vertical 
or horizontal direction 
by a set of gears. 

The method of 
operating these direct- 
current furnaces was to 
employ both arc and 
resistance heating for 
melting the charge of 
metal and for the after 
refining operation, the 

el6*«de. l„i„g raised ^^ ^^-"fff 1^^ ^'"'"" 
just clear of the molten 

slag when the highest temperature was desired. Under these 
conditions of work two arcs were formed, one as the current 
entered the slag from the first electrode, and another as the 
current escaped from the slag by the second electrode. The 
heat of these two arcs, and that developed in the slag itself 
by the passage of the current between the point of ingress and 
egress, raised the slag to a very high temperature, which was 
transferred to the metal lying beneath it. Both oxidising and 
reducing effect could be obtained by varying the composition 



48 ELECTRO-THERMAL METHODS 

of the slag. The slag, it may be explained here, is employed 
in the Heroult refining proeess as a scavenging agent, the 
number of slags required to purify the metal depending upon 
the amount of impurities in the original charge, and upon the 
purpose for which the finished metal is required. 

The use of an air-blast to produce an oxidising effect was 
abandoned very early in the trials of the Heroult furnace, and 



Fig. 23.— General View of the Steel Works at La Pi-az, Prance. 

iron ore is now used to produce an oxidising slag when this is 
required. Another change introduced into the methods oE 
working is that the electrodes are never allowed to dip into 
the slag, and that arc-heating is therefore alone employed. 
The method of work with this early type of furnace was as 
follows : — 

A charge of steel-scrap, pig-iron, iron ore and lime — in the 
requisite proportions and quantities — was placed in the furnace, 
and this was raised to the melting point by combined arc and 
resistance heating. The slag formed by the lime and silicates of 



HEROULT ELECTRIC STEEL REPINING FURNACE 49 

the ore rose and floated on the surface of the molten metal. The 
further heating of the charge occurred by allowing the electrodes 



to dip just beneath this slag, but not into the metal beneath it. 
Iron ore was then added to the charge to produce an oxidising 



50 ELECTEO-THEEMAL METHODS 

slag. Under these conditions the impurities of the iron and steel 
scrap become oxidised and entered the slag. By pouring oflf this 
slag, therefore, and by renewing the materials which formed it 
once or twice, a very pure product could be obtained. The 
process was in reality a washing-out process, in which the slag 
acted as solvent. The fact that all the heating with this type of 
furnace occurred without any actual contact between the carbon 
electrodes and the metal also conduced to the purity of the pro- 
duct, since neither silicon nor carbon could enter into the steel 
from the electrodes. When the steel in the crucible had been 
raised to the requisite degree of purity by this washing-out pro- 
cess, a calculated amount of an iron alloy, high in carbon, was 
added, and the resultant steel (of known carbon contents) was 
tipped into the casting ladle. 

Description of the 15-ton Furnace at Chicago. 

The following details of the construction and methods of work 
of the 15 -ton furnace at South Chicago are taken from a paper 
by C. G. Osborne, read before the Chicago Section of the American 
Electrochemical Society in January, 1911. They show that only 
slight changes have been found necessary in the Heroult furnace 
when worked with three-phase in place of direct current, and with 
charges of metal five times larger than those used in the early 
furnaces. 

Upon a solid foundation about 5 feet above the ground-level, a 
Btationary rack 8 feet 9 inches long is fastened. Upon this rack the 
furnace proper rests on a floating pinion, fastened to its shell by rivets. 
The arc of this floating pinion has a radius of 10 feet, and aims to give 
the furnace an angle of approximately 29° when tilted over to its full 
extent. 

Attached to the extreme back of the furnace is an 18-inch plunger 
with a 4-foot stroke, working in a cylinder attached to an hydraulic 
pipe line of 500 pounds pressure to the square inch. This gives a 
lifting power, approximately, of 45 tons. The balance of the furnace is 
so arranged that the equilibrium is never upset, and therefore to return 
to the liorizontal position merely requires the releasing of the pressure, 



HEROULT ELECTRIC STEEL REFINING FURNACE 51 

and the furnace returns of its own weight. It will be noted that the 
floating pinion and rack requires some provision for the forward 
position of the furnace when tipping. This is taken care of by having 
a movable cylinder, pivoted at both the top and bottom, which, 
allows the cylinder to follow the motion of the furnace. 

The furnace shell is built up of plate steel, 1 inch in thickness, 
riveted together. The outside horizontal cross-section plan is approxi- 
mately that of a complete circle of 13J feet in diameter, with two 
flattened portions situated at the front and back respectively. 

On the bottom of the furnace, within the 1-inch plate, aild next to it, 
one row of magnesite brick (laid the 4J-inch way) is placed across the 
flat portion. The side walls of the furnace are vertical and consist of 
two rows of magnesite brick, laid the 9-inch way, giving a thickness of 
18 inches of magnesite brick. These solid magnesite brick walls extend 
up to the furnace roof. The bottom of the furnace consists of dead- 
burned Spaeter magnesite to a depth of 12 inches at ita thinnest point, 
which is, of course, at the extreme centre. From this thinnest point 
the bottom slopes gradually upwards so as to form a portion of a 
sphere 7 feet 2 inches in radius. The furnace bottom was made in the 
following manner : Dead-burned and carefully gi'ound Spaeter magne- 
site was mixed with basic open-hearth slag, in the proportion of four 
of magnesite to one of open-hearth slag. To this mixture, sufficient 
tar was added to make the mass sufficiently plastic, to be tamped into 
the furnace in the usual manner. The entire depth of the bottom was 
tamped in this way. Next, the furnace was filled with wood, dried 
out for about forty-eight hours, and then filled with coke, and the 
electrodes lowered and the current turned on. In this way the bottom 
was fluxed into place. 

The furnace roof is of silica brick 12 inches in thickness, and is 
" sprung " from a movable ring. This ring is fitted with a top and 
bottom angle iron to take a skew-back brick, and from this the arch is 
spanned across the 10-foot interior of the furnace with an 8-inch rise. 
The bricks are set in circles parallel to the steel ring, the usual wooden 
wedges being placed here and there, to take care of the subsequent 
expansion of the brick. Holes for the electrodes are left in the roof by 
means of templates, and the bricks are held in position around these 
holes by lateral pressure. 

There are five doors, two on each side of the furnace, and one in 
front over the pouring spout. These doors are of cast-iron, lined with 
clay brick, laid the 4J-inch way. They work in the usual groove 
arrangement and are operated by steam pressure of about 150 pounds. 
The front door over the pouring spout is an exception to this, being 
operated by hand with a counter-balance. 

E 2 



52 ELECTRO-THERMAL METHODS 

The tlu-ee eleotrodes are lowered through the roof in the form of an 
equilateral triangle, each side of which ia 5 feet 2 iuchea in length, the apei 
of thia triangle pointing directly towards the back of the furnace. The 
center of this triangle coincides with the center of the fiirnace roof. 
There are three separate holders, one for each electrode. Each holder 



Fig. 2o.— Heroult 15-Toii Furnace at Worcester, U.S.A. 

is constructed of a solid water-cooled copper casting, bolted directly to 
the bus-bar. In front these holders are split, and are joined with a 
right and left screw which enables the holder to be opened or closed at 
will. The holders are designed to carry a 24-inch electrode, but 
by means of contact blocks any smaller-sized electrode can be employed. 
The electrodes used early in June, 1911, were 14-inch square carbon 



HEROULT ELECTEIC STEEL REPINING FURNACE 53 

electrodes manufactured by the National Carbon Co., of U.S.A., and a 
cooling box through which, water was kept in constant flow, was placed 
round the electrode. This box rested on the roof of the furnace, and 
movable plates were set in position round it and the electrode, to make 
a gas-tight joint. 

The weight of the electrodes is supported by the chains which extend 
over pulleys, to the drums at the back of the furnace. The electrodes 
are kept in alignment by vertical guides, and are regulated by individual 
motors placed at the back of the furnace. The regulation may be 
either by hand, by controllers, or by an automatic device. 

The operating platform of the furnace is raised about 9 feet from 
the ground level. Around the furnace on this platfonn, at convenient 
points, bins are placed for storing the miscellaneous fluxing materials 
used in furnace operations. The front part of the furnace platform is 
cut out to allow a ladle to be hung in position, when the furnace 
is tapped, and for any miscellaneous work in the pit. 

The pouring platform is 30 feet long, and is sufficiently large to 
admit eight moulds to be placed in position for pouring. 

The power for the furnace is generated by dynamos having as 
prime movers, — reciprocating gas-engines, reciprocating steam-engines, 
also high-pressure and low-pressure turbines. It is three-phase in 
character, and is generated at 2,200 volts and 26 cycles. The cost of 
this supply is half a cent, per kw. hour as measured at the meters. 
At the electric furnace it is stepped-down by means of three 750-kw. 
transformers, to the voltage of the furnace. These transformers are so 
arranged with switches, that the primary turns may be altered to give 
secondary voltages of 80, 90, 100, or 110 volts, as desired. Ordinarily 
90 volts is used. 

The entire building is spanned by a 50-ton crane. The normal 
operation of the furnace is as follows : — 

Ordinary Bessemer pig-iron is full blown in a 15-ton Bessemer 
Converter, in from eight to twelve minutes. It is then poured directly 
from the Bessemer vessel into the electric furnace transfer ladle, and is 
drawn to the electric furnace building, a distance of about a quarter of 
a mile. This requires about five minutes, and, as a precaution against 
the possible formation of a skull in the ladle, the Bessemer charge is 
blown about 1,500 pounds of scrap "hotter'^ than in ordinary 
Bessemer practice. 

Immediately the ladle is received at the electric furnace it is picked 
up by the crane, slightly tilted, and the silicious slag is completely 
cleaned off by hand-rabbling. The metal is now ready for charging. 
To do this, the ladle is merely turned over on its trunnions, and the 
metal is poured into a spout through which it flows to the furnace. 



64 ELECTfiO-faEfiMAL METHODS 

The operation of cleaning off the slag and cliarging owupies from five 
to ten minutes. As the metal is being poured the furnace men shovel 
iron oxide and lime into the furnace tUrough the working doors. The 
electrodes are then lowered and the current is turned on. 



l 

I 
i 



A basic oxidising slag is first produced ; this removes the phosphorus. 
In about tliirty minutes this slag has served its purpose ; tite fujnace 
is tilted slightly forward and the slag is removed in from five to ten 
minutes as before, by hand -rabbling. The recarburiser is now added. 



HEROULT ELECTRIC STEEL REFINING FURNACE 55 

On the bare surface of the oxidised metal lime is then quickly spread^ 
with sufficient fluorspar to keep the mass fluid. In about fifteen 
minutes this lime is melted, and coke dust is thrown on to the slag 
beneath each of the three electrodes. Under the influence of the electric 
arcs calcium carbide is produced in gradually increasing quantities. 
As soon as this position is reached, a neutral if not actually reducing 
atmosphere has been obtained. From this point to the finish, there is 
practically a dead -melt in a reducing atmosphere. The slag at this 
stage of the process is fluid and highly basic. If a sample should be 
taken and water be added to it, the resultant acetylene gas, from the 
well-known calcium carbide and water reaction, is of sufficient quantity 
to light and burn for half a minute. 

Tests are now taken to show the condition of the steel. A small 
cylindrical test piece is poured and is forged to a round pan-cake shape 
under a steam-hammer located at the furnace. If this forged sample 
shows by its appearance a satisfactory condition of the metal, the bath 
is tapped. If not, further refining is necessary. 

To tap the furnace, the electrodes are raised from the bath, the ladle 
is swung by a crane under the pouring spout, and the tilting lever is 
then pulled forward. The pouring is done through a 1 J inch nozzle 
into moulds of varying sizes. 

A typical furnace charge sheet is shown in Table V. 



Table V. 



li^lectric Furnace Charge Sheet, Illinois Steel Co., South Chicago. 

Material used. 







Pounds 


Converter-blown metal 


30,000 


Scale . 


• • • « 


700 


Ferro-manganese, 80 


per cent. . 


200 


Ferro-silicon, 10 per 


cent. . 


60 


Ferro-silicon, 50 per 


cent. . 


80 


Recarboniser 




130 


J^'luorspar . 




400 


Coke dust . 




200 


Lime, first slag . 




600 


Lime, second slag 




600 


Dolomite . 




400 


Magnesite . 




25 



56 



ELECTHO-TflERMAL METHODS 



Table V. — continued. 

Time Required for Electric Furnace Operation. 

A. M. 



Tapped previous heat 


. 7 :00 


Metal ordered for 


. 7 : 15 


Metal received . 


. 7 : 15 


Began fettling . 


. 7 : 17 


Current on 


. 7 : 27 


Skg-off , began . 


. 8: 00 


Slag-off, finished 


. 8:11 


Tapped 


. .. 8:48 


Time of heat 


. 1 hour, 21 minutes 



It will be seen from this table that it takes from 1|^ to 2 hours to 
complete a heat, according to the grade of steel produced. 

What is actually done in the electric furnace at the South Chicago 
Works of the Illinois Steel Company, is to take oxidised blown metal, 
and to produce deoxidised steel, low in sulphur and phosphorus and 
(within reasonable limits) of practically any analysis required by^ the 
consumer. The steel charged has approximately the following 
analysis : — 

Carbon, '05 per cent, to *10 per cent. ; Sulphur, '035 per cent, to 
'070 per cent. ; Phosphorus, '095 per cent. ; Manganese, '05 per cent, to 
•10 per cent. ; Silicon, '005 per cent, to '015 per cent. 

This furnace has produced high-grade alloy steels, high-grade 
carbon steels, and ordinary steels, and according to Osborne has 
operated on a greater variety of products than any other elec- 
trically-heated furnace in the world. 

As to the mechanical tests of the steel made by the Heroult 
electric process at South Chicago, the following data were 
obtained at the mechanical testing plant of the Illinois Steel 
Company : — Elastic limit, 35,000 — 47,000 lbs. per square inch ; 
tensile strength, 60,000 — 70,000 lbs. per square inch ; elongation, 
25 to 30 per cent. ; reduction of area, 43 to 60 per cent. As to the 
difference between this electric steel and acid open-hearth steel, 
it was stated that the same tensile strength was obtained with 
the electric steel with lower carbon tests than with open-hearth 



HEROTJLT ELECTBIC STEEL REFINING FURNACE 57 

steel. For example, a '10 per cent, carbon electric steel averages 
the same tensile strength as a '15 — '17 per cent, carbon acid 
open-hearth steel. 

In the course of the discussion on Osborne's paper, it was 
stated that at South Chicago ferro-silicon was employed in finish- 
ing rail steel, but was not used in an ordinary way for deoxidising 
purposes. There was found to be less loss from segregation in 
the ingot with electric steel than with open-hearth steel ; this is 
ascribed to its greater density and to its greater freedom from 
occluded gases. The furnace required 1,950 kw. to operate it. 
Of this total 750 kw. was necessary to maintain the 15-ton 
charge at the proper temperature for the refining operation (to 
balance radiation and other heat losses), while the full power was 
only employed when the charge was being heated up. The 
furnace was not run continuously, and on restarting after cooling 
down at week-ends and at other times, it was prepared for its 
charge of molten metal, by the use of coke and of an electric 
current, or by the aid of oil burners. 

No costs figures have been published for the operation of 
either the South Chicago or Worcester 15-ton furnace, and only 
a few detailed figures for the power consumption have been given 
to the public. Assuming that the average power used per charge 
at South Chicago is 1,350 kw. and that the average time per 
charge of 30,000 lbs. is 80 minutes, the results would show 119 
kw. hours per ton of 2,000 lbs. The figures given in Tables VI. 
and VII., from an unsigned article appearing in the issue 
of Metallurgical and Chemical Engineering for April, 1910, support 
this estimate of the power consumption of the South Chicago 
furnace, when working under normal conditions, with molten 
metal from the Bessemer Converter. This method of working, 
it may be noted, is covered by the U.S.A. patent No. 934247 
of Sept. 1909 in the name of A. R. Walker. 

Table VI. gives the power consumed when refining metal high 
in phosphorus and sulphur, while Table VII. gives the corre- 
sponding figures for a metal low in phosphorus. 



58 



ELECTEO-THERMAL METHODS 



Table VI. 



Net weight charged. 
Lbs. 


Kw. hours used. 


Time. 


29,000 


2,000 


1 hour 20 luiniites. 


28,200 


2,300 




, 35 


28,200 


2,500 




, 15 


28,000 


2,200 




, 30 


26,600 


2,100 




. 15 


26,000 


2,200 




, 40 


25,700 


2,900 






23,000 


2,500 


1 


. 35 


28,000 


2.400 




, 35 


27,000 


2,300 




, 35 


27,400 


2,700 




, 45 



Table VII. 



Net weight. 
Lbs. 


Kw. hours. 


Kw. hours 
per metric ton. 


28,000 


1.400 


1100 


27,600 


1,700 


135-5 


27,000 


1,400 


1141 


28,000 


1,000 


78-5 


28,000 


1,300 


102-1 


28,400 


1,300 


100-8 


27,800 


1,000 


79-2 


27,600 


1,500 


119-5 


28,100 


1,200 


93-9 



The average energy consumption of the eleven heats recorded 
in Table VI. was 88*4 kw. hours per 1,000 lbs. net weight, or 
194*5 kw. hours per net metric ton ; while the average energy 
consumption of the nine heats of Table VII. was 47*2 kw. hours 
per 1,000 lbs. net weight, or 103*8 kw. hours per net metric ton. 

Concerning the composition and reliability of the steel made 
at the South Chicago furnace, the following figures (Table VIII.) 
may be quoted from the same article. 

The first line, marked " Specification " gives the desired 



fiEEOtLT ELECTEIC STEEL BEFININO FURNACE 59 



specified composition of the steel ; while the following lines 
marked " Analysis/* give the analyses of the steel produced in 
eight successive heats : — 

Table VIII. 





C 


s 


P 


Mn 


Specification : 
Axle steel . 


( 35 to 1 
( 0-45 ) 


003 


0-03 


0-37 


Analysis : 

30,000 lbs. 
29,000 „ 
30,000 „ 
30,000 „ 
30,000 „ 
30,000 „ 
30,000 „ 
30,000 „ 


•45 
•37 
•38 
•35 
•41 
•48 
•42 
•35 


0-032 
•028 
•028 
•031 
•030 
•025 
•030 
•030 


0031 
•033 
•026 
•037 
•039 
•032 
•027 
•028 


0^49 
•42 
•40 
•38 
•37 
•41 
•44 
•34 



The cost of repairs is stated to be low, and is given by the same 
writer as follows : — 

A silica roof costs $60 ; if it lasts for 129 heats the cost of the roof 
per ton treated is about 3 cents. The 10 lbs. of dolomite at $6 
per ton, required for repairing the lining per ton of steel, costs also 
about 3 cents. Hence, the total cost of repairs of the furnace proper, 
is approximately 6 cents per ton. 

Campbell in a recent paper, states that the cost of repairs to 
the roof in the latest type of Heroult furnaces is about 2^(1. per 
ton of steel produced. This is higher than the American figures. 

The consumption of electrodes is given as 6 lbs. per ton of 
steel, this figure applies both to graphite and to amorphous 
carbon electrodes. 

Considerable space has been devoted in this Chapter to a 
description of the methods of work and results obtained with the 
Chicago furnace, on account of the size and importance of this 
installation, and also because of the full particulars that are 
available concerning it. 



60 ELECTEO-THEEMAL METHODS 

The Worcester Furnace. 

No detailed figures have been published for the power consump- 
tion or for the repairs costs of the 15-ton Heroult furnace installed 
at the works of the American Steel and Wire Company, at Worcester, 
Mass. It is known, however, that this furnace, which has been 
operating since January, 1910, is in some respects more easy to 
work than the Chicago furnace, and that as it is charged with Talbot 
open-hearth steel already largely dephosphorised, the time of the 
heats is shorter, and the specific energy consumption is less (see 
Table VI.) than that of the earlier erected furnace. The steel 
produced at Worcester was employed originally for the manu- 
facture of the wire billets used for the finer varieties of wire. It 
was stated, however, in a recent discussion, that this steel had 
not been found as suitable for wire making as the steel billets 
formerly used, and doubtless some other product is now being 
made in the Worcester furnace. Fig. 25 shows the 15-ton 
Worcester furnace, and Fig. 26 the same furnace tipped for 
discharging. 

Other specially interesting installations of the Heroult furnace 
will now be dealt with briefly. 

Other Installations. 

At the Stahlwerke of Eichard Lindenburg, at Eemscheid- 
Hasten, in Germany, two furnaces of 2,500 — 3,000 kgs. capacity 
are producing tool and gun steels from molten steel, charged from 
a Wellman tilting open-hearth furnace. According to Eichoff 
the method of work at this plant is as follows : — 

From a Wellman tilting open-hearth furnace IJ to 2 tons of liquid 
steel, partially purified, are poured into the electric furnace, care being 
taken to hold back the slag. The bath is covered with an oxidising 
slag, and the current is turned on. After the lapse of one-half to 
three-quarters of an hour this first slag is carefully drawn off, the clear 
bath is covered with a weighed amount of carbon, and a fresh amount 
of slag, free from oxides, is charged. This slag is melted after twenty 
minutes, and then, through the action of the arc upon the slag, it 
is thoroughly deoxidised, calcium carbide being formed. In this 
manner the bath is completely protected against access of air. The 



HEROULT ELECTRIC STEEL REFINING FURNACE 61 

charging of the neutral slag cools the bath so much that the greater 
part of the protoxide of iron is reduced by the laj-er of carbon. A 
certain quantity of manganese ore is also charged with the neutral slag. 
This too is reduced and destroys the last small balance of the protoxide 
of iron. When the slag has become quite white, a sample of the steel 
is taken and its carbon content is determined. A mixture of iron and 
carbon, accurately calculated, is added, and when dissolved, the necessary 
addition of manganese and of ferro-silicon is charged, to produce the 
desired quality. The steel is then tapped. So far as phosphorus is 
concerned, the analysis of the steel in a well-managed charge fluctuates 
between 0*003 and 0*005 per cent., while sulphur ranges from 0*007 to 
0*012 per cent. As a rule, carbon, manganese and silicon can be 
accurately kept within limits of 0*03 to 0*05 per cent. The elimination 
of the sulphur takes place during the last stage of the process, and 
seems to be due to the fact that a much more basic slag can be used in 
the electric process, on account of the much higher temperature avail- 
able. When the steel is taken in a highly oxidised condition from the 
Wellman furnace it carries about 0*01 per cent, of phosphorus, and may 
be directly covered with carbon and the neutral slag. This makes it 
possible to finish a charge in one and a quarter hours, with a power 
consumption of 200 kw. hours per ton of steel. 

The steel produced under these conditions, according to Eichoff, 
may be kept for hours under a neutral slag without changing its 
quality, and a part of the heat may be cast, and the balance be worked 
over to another grade, a convenience which is of great importance to 
steel-founders. The steel may also be allowed to chill, and may then 
be re-melted without affecting its quality.^ 

Heroult Furnace at a Foundry in Essex, England. 

An installation of a different character is that recently com- 
pleted at the steel foundry of Messrs. Lake & Elliot, at Braintree, 
in Essex, England, where castings for the motor trade are the chief 
speciality. This plant is of special interest, not only because it 
was the first works in England where an electric furnace was 
employed solely for foundry work, but also because it is located 
in a district where cheap power is unobtainable. Messrs. Lake & 
Elliott have therefore been compelled to generate their own power. 

The generating plant consists of a gas-producer, of a 
Westinghouse gas-engine, and of a single-phase alternator. 

1 Electrochemical and Metallurgical Industry^ February, 1907. 



62 ELECTRO-THERMAL METHODS 

The gas-engine is of the vertical tftadem type, with 8 cylinders, 
and is capable of giving 450 b.h.p. continuously, and 500 b.h.p. 
lor periods of half an hour. The alternator has a capacity at 
normal full-load, of 300 kw. at a pressure of 110 volts. The 
current is single-phase alternating, and the periodicity 25 cycles 
per second. This alternator is directly coupled to the gas-engine. 

The furnace is of 2 tons capacity, and is of the standard 



Fig. 27.— The Thtiry Eegulating Apparatus at Braintree, Esses. 

Eingle-phase Heroult type, using two electrodes. Figs. 21 
and 22 show views of the furnace. The furnace rests on a 
concrete foundation, 2 ft. 6 ins. above the level of the foundry 
floor. When skimming-off the first slag, the middle part only of 
the platform is raised, and a shallow bogie is run in beneath it. 
When the slagging is finished, this bogie is run out again. It 
will be seen that this bogie, when in position for receiving the 
slag, rests on a sliding platform, wliich is pushed back when 



HEROULT ELECTRIC STEEL REFINING FURNACE 63 

the furnace ia ready for tapping, thus allowing room for the 
ladle. 

The case for the automatic regulators, which are of the Thury 
type (see Fig. 27), and are used for maintaining the arcs at 
a constant length, is built into a wall between the engine-room 
and the foundry, so that the regulators are accessible both by 
the foreman melter in the foundry, and by the electrician in 
the engine-room. The 
furnace is tilted electri- 
cally, a motor of 6 h.p. 
being employed. The 
control of the tilting 
mechanism is placed 
immediately in front of 
the furnace. 

The method of work- 
ing the furnace is that 
usually employed when 
melting and refining 
scrap in a Heroult fur- 
nace. The - Bcrap em- 
ployed is a mixture of 

horse-shoes, castings, and Fig. 28.-Tho Braintree Heroult Furnace 
foundry scrap, together (diacharging). 

with boiler-puuchings and miscellaneous heavy steel-scrap of 
small dimensions. 

The furnace is served by a 5-ton overhead electrically driven 
crane. Steel from the furnace is received in a 2-ton bottom 
teeming ladle (Fig. 28) the actual casting being performed 
through the intermediate use of hand-shanks, and in the case of 
the larger castings, by direct casting from ladle. By the use of 
a bottom-teeming ladle, a ready method is obtained of delivering 
small and intermittent quantities of steel, free from slag, both to 
shanks and to moulds. 

The steel made ia, of course, exclusively dead-soft, testing 



64 ELECTEO-THEEMAL METHODS 

between '10 and '15 per cent, carbon, with manganese and silicon 
varying slightly, according to the special mechanical properties 
required. Owing to the refining power of the electric furnace, 
the sulphur and phosphorus are extremely low, being together 
less than '03 per cent. 

As a result of the absence of sulphur, the proportion of 
cracked castings is reduced to a minimum. Cracking or tearing 
is generally due to contraction over large surfaces. The size, 
shape and condition of cores will frequently not permit the 
necessary shrinkage to take place ; this sets up stresses in the 
steel which are sufficient to cause rupture. For case hardening, 
the Braintree steel is quite equal to the best crucible steel of the 
same carbon contents. 

Other Heroult Furnace Installations in England. 

Furnaces of similar size and capacity have been in operation 
at Messrs. Edgar Allen's, at Messrs. Vickers, and at Messrs. 
Thomas Firth & Sons, Sheffield, since 1910 ; and an 8-ton furnace 
in 1912 was in course of construction at Messrs. Vickers' 
works. At Messrs. Edgar Allen's Foundry molten steel from 
an open-hearth furnace is employed for charging the electric 
refining furnace, while at Messrs. Thomas Firth & Sons, and 
Vickers', cold scrap is used. 

The most important development of electric furnace work in 
England is that at the Skinningrove Iron Company's Works, at 
Carlin How, Yorkshire, where the erection of a 15-ton furnace 
is planned. This furnace will be operated entirely by elec- 
tricity generated from the waste-gases of blast-furnaces and coke- 
ovens, and will produce a high quality of rail-steel, from metal run 
into it from a Talbot melting furnace. The cost of electrical power 
at this plant is expected to be about '26d. per kw. hour, or about 
the same as that of the Chicago plant, which is also operated by 
gas-power. 

As regards the power consumption of the smaller type of 
Heroult furnace, when melting and refining steel scrap, the 



HEROULT ELECTRIC STEEL REFINING FURNACE 65 

following figures, showing the work of the 2J-ton experimental 
furnace at La Praz, France, for the week ending December 24th, 
1911, have been placed in the writer's hands by the Societe 
Electrometallurgique, Francaise, who own and control the 
Heroult patents. 

Table IX. 

Output of one 2^ton Heroult Eleotrio Furnace at La Praz, France, 
Melting and Refining Scrap Steel with Two Slags. 

Week ending December, 24th, 1911. 

Hours worked, 126. 
No. of heats, 26. 
Average hours per heat ) 

including all repairs v 4 hours 51 minutes. 

and charging. ) 

Tons. Cwts. Qrs. Lbs. 
Total weight teemed, 62 14 2 6, or 140,510 lbs. 
Shortest heat, 3 hours 10 minutes. 

Lowest power consumption at furnace, 459'2 kw. hours per 1,000 kgs. 
Average power for week at furnace, 528 kw. hours per 1,000 kgs. 
Percentage of clean ingots 93 per cent. 

„ scrap 3 

Oxidation, etc. 4 „ 

Note : The last heat was the 107th heat made with the same roof, 
and this was apparently fit for 10 more heats. 

Making allowances for the difference in the time taken to 
refine each charge of metal, these figures represent a larger 
power consumption than the corresponding ones for the South 
Chicago furnaces, and the economy of installing large furnaces, 
heated by three-phase current becomes manifest. In order to 
obtain the higher efficiency and other advantages of three-phase 
current generators, small furnaces are being adapted for this 
method of working, and the Konigliche Ungarische Staatseisen- 
werke, at Diosgyor, in Hungary, are now installing a 2,000-kg. 
furnace of this type. 

The 8-ton Heroult furnace erected in 1912 at Messrs. Vickers' 
Works, Sheffield, is also of the three-phase type,' and the last 

B.T.M. F 



66 ELECTEO-THERMAL METHODS 

report received by the author states that this furnace is giving 
excellent results. 

Further Developments of the Heroult Furnace. 

The future developments of the Heroult Electric Steel Refin- 
ing furnace and process would appear likely to be in the direc- 
tion of utilising three-phase current for all sizes of furnace, and, 
where large installations are concerned, of employing metal from 
Open-hearth Furnaces or from the Bessemer Converter, as raw 
material for the final operation. 

Over one-half of the large Heroult furnaces now operating 
are using molten metal from Martin, Wellman or Talbot furnaces 
for charging purposes, and in the writer's opinion this method 
is likely to become generally adopted. 



CHAPTEE V 

THE GIROD ELECTRIC STEEL REFINING FURNACE 

The total number of electric steel refining furnaces of the 
Girod type in use on May 1st, 1912, according to figures 
supplied by M. Girod, was fifteen, with an aggregate capacity per 
charge of 66 tons, while five additional furnaces, having an aggre- 
gate charge capacity of 20 tons, were under construction. 
Since the larger number of the furnaces are working with cold 
scrap, etc., and are producing steel for fine castings and for 
guns and projectiles, only three heats can be made per twenty- 
four hours ; and the total daily output of the fifteen furnaces in 
operation in 1912 was 225 tons of fine steel. 

The largest furnaces yet constructed or operated are of 12 
tons capacity. The fact that of the five furnaces under construc- 
tion in 1912 only one was of 8 tons capacity and the others were 
of 2, 3 and 4 tons, would appear to indicate that the Girod type 
of furnace yields the highest efiBciency and best results in the 
smaller sized units. 

The most notable installations of the Girod furnace are to be 
found at the Forges et Acieries il^lectriques Paul Girod, at Ugine, 
in Savoie, where six furnaces are at work (two of 12 tons) ; and at 
the works of Fried Krupp, at Essen, where one 12-ton furnace is 
in use. A complete list of the twenty furnaces operating or under 
construction is given in the Appendix. The 12-ton furnaces are 
charged with cold scrap, and are worked chiefly to produce the 
special steels required for guns and projectiles. Only at the 
Giitehoflfnungshiitte, at Oberhausen, at the Oberschlesische, 
Eisen-Industrie, at Gleiwitz, and at the Usines Pontiloff, at St. 
Petersburg, is molten metal employed for charging the Girod 
furnaces. 

f2 




Fia. 29.- 



68 ELECTRO-THERMAL METHODS 

General Constmotion of the FuriLftoe. 

The hearth of Girod'e electric steel-making furnace coneists 
of a circular or oblong cavity, in which the metal when molten 
reaches a height of from 
25—80 cma. One or 
more electrodes of a like 
polarity are suspended 
above the bath, and soft 
steel pieces embedded in 
the hearth of the furnace 
and in direct contact 
with the molten metal, 
form the negative elec- 
trodes. The electric 
current, entering by way 
of the upper electrode, 
forms an arc between itself and the bath, traverses the bath, and 
passes out through the lower electrodes. The upper parts of 
these lower pole pieces 
become molten at their 
extreme ends ; but their 
length is not decreased 
by more than 6 or 10 
cms., as has been proved 
by making sections of 
these pieces when cold, 
after several months' 
work. With a view to 
reducing the length ol 
the fused part, and also 
to preserving the lower 
lining of the furnace intact, the extreme end of the pole pieces 
are water-cooled. The details of the cooling arrangement are 
shown in Eig. 37, and consist of a cavity on that part of the 
piece which projects outside of the furnace frame. This 




GIROD ELECTRIC STEEL REFINING FURNACE 69 

projection carries likewise the device for leading the current to 
the poles. 

The design of the refining furnace has not been altered in any 
material point, since the first English patent was taken out by 
Girod for a tilting crucible furnace, electrically heated, in 
1904. Figs. 29 and 30 show a plan and sectional elevation of 
the early furnace, and Figs. 31, 32 and 33 represent the 





(b 
oO 


Ov 

Oc 








^O 


cy 



w/MWMmmmj 




Fig. 31. — Plan of latest 8 -ton Girod Furnace. 

latest form of furnace. The changes that have been- intro- 
duced, as the result of experience, relate chiefly to the arrange- 
ment and grouping of the negative electrodes in the base of 
the furnace, and also to the grouping of the conductors and 
cables in order to minimise the losses arising from induction 
when operating the furnace with three-phase currents. 

The Earlier type of Oirod Furnace. 

The earliest type of Girod furnace consisted of a shallow iron 
tank, cylindrical in shape, mounted on trunnions and lined with 
magnesite brick.^ The removable cover was made of silica 

1 "The Electric Furnace in Iron and Steel Production," J. B. C. Kershaw, 
Electrician Publishing Co., 1907, p. 51. 



70 



ELECTRO-THEEMAL METHODS 



brick, and was perforated by openings for admission of the carbon 
electrodes. The bottom of the furnace was formed of a number of 
pieces of cast-iron embedded in the channelled brickwork — these 
acted as the lower or negative electrodes of the electrical circuit. 
For a furnace 2 metres in diameter, fourteen of these electrode 
plates were used. Each plate was in contact with the contents 
of the crucible of the furnace by means of canals, which were 
filled with molten iron before the work commenced. Alternating 
current was employed. The upper electrodes were suspended in 




Fig. 32. — Sectional Elevation of latest 8-ton Girod Furnace. 

the slag, and the decarbonisation of the charge was carried as 
far as possible. The steel was then recarburised, by adding a 
calculated weight of high carbon metal. A furnace of this type, 
utilising 250 kw., was operated at the Electrometallurgical Works 
at Albertville in 1907, and was producing 1 ton of steel from 
1 J-ton charges in 4J hours per heat. 

Description of the Latest Oirod Furnace. 

The details of the latest Girod refining furnace are illustrated 
in Figs. 31 to 36. The hearth of the furnace is formed by a 
rectangular iron shell, and is lined with crushed dolomite in 



GIEOD ELECTEIC STEEL EEFINING FUENACE 71 



place of the earlier used and more expensive magnesite. The 
furnace is provided with three charging holes closed by sliding 
doors, and with a tapping hole on the opposite side through 
which the molten metal can be discharged. A metal framework 
supports the arched roof, which is made of silica brick, and has 
openings in it for the four carbon electrodes, which hang vertically 
with their lower ends near to but not touching the slag layer. 

At the bottom of the furnace and removed as far as possible 
from the upper carbon electrodes, six or more steel electrodes are 
embedded in the refractory bottom, and are in direct connection 
with the furnace shell 
and with the low- 
tension side of the 
power plant. Since 
these bottom elec- 
trodes are placed as 
far as possible from 
the upper ones, the 
current passes through 
all the charge, and by 
this means the whole 
mass is uniformly 
heated. The current 
in crossing the bath 
also produces an electro-magnetic field, which gives the bath a 
rotary movement quickiBning the chemical reactions. As the 
steel electrodes are water-cooled, their life is practically unlimited. 
The steel frame of the furnace is placed on bearings, so that the 
furnace can be tilted .forwards for the tapping, or backwards for 
the removing of the slag. This is effected by the charging 
doors. The tilting movement is obtained either by an electric 
motor or by an hydraulic plunger. The electrodes are of round 
section and of different sizes, and are made at Ugines in a factory 
fitted up with all modern improvements. Their electric resis- 
tivity on an average is 4,000 microhms per square centimetre of 




Fig. 33. — Sectional Elevation of latest 8-ton 

Girod Furnace. 



72 ELECTEO-THEEMAL METHODS 

section ; their density is 1*65 to 1*80. The sectional area of the 
electrodes is so calculated that the current intensity does not 
exceed 5 — 6 amperes per square centimetre. 

Current and Voltage Reqnirements. 

Any kind of current, continuous, single-phase, or three-phase, is 
stated to be suitable for the Girod electric refining furnace. The 
E.M.F. required is about 65 volts for small furnaces, and 70 volts for 
the larger furnaces. The frequency may go up to 50 periods, 
but on account of the effects of self-induction it is better to have 
a low frequency, as this produces a higher electrical efficiency. 
The low voltage also minimises the dangers for the workmen. 

Single-phase alternating current is found to be specially suit- 
able for furnaces of small capacity, with only one carbon electrode.. 
Its use, however, entails the necessity for installing rotary trans- 
formers, which have about 14 per cent, transformation losses. 
Three-phase current, on the other hand, is specially adapted for 
large furnaces, and can be employed wherever it is possible to 
contfect the furnace directly to the alternator. The use of three- 
phase current also obviates the losses arising from the use of 
rotary transformers. Step-down transformers, for bringing the 
E.M.F. down to the voltage required, are, however, still necessary. 

A special star connection is used when working the Girod 
furnace on the three-phase system, the principle of the connec- 
tion being that one of the phases is reversed in relation to the 
other two. When the intensity of the current is equal in the 
three upper electrodes, the equilibrium of the three phases is 
perfect, and the current in its passage through the molten metal 
in the furnace heats the whole charge equally. The following 
claims are made for the Girod furnace when operated with 
three-phase current : — 

(1) Simplicity of construction. 

(2) Ease of management and control. 

(3) Economy in power consumption. 

(4) High thermal efficiency. 

(5) Quiet melting of cold charges. 



GffiOD ELECTEIO STEEL BEFINING FDKNAOE 78 



74 ELECTRO-THERMAL METHODS 

/ 

Electrical Connections. 

The losses involved by different cable arrangements for con- 
veying the current to the furnace have been most carefully 
studied at the Gutehoffnungshiitte, and the result of this study 
has been made public in the article referred to below.^ The 
plan finally adopted, to reduce the induction Josses to a minimum 
at this works, was to arrange the cables systematically around 
the furnace, as in Fig. 36 ; A and B being the earlier arrange- 
ments which were found unsatisfactory in practice. The 
advantages claimed for the new arrangements, shown in 0, 
are : — 

(1) The electric arc circling about the periphery of the carbon 
electrode causes a strong agitation of slag and metal. This 
accelerates the speed of reaction between the slag and the 
molten iron in the furnace, and therefore reduces greatly the 
time of refining. 

(2) The arches of the roof, as well as the furnace walls, 
receive a more uniform radiation from the electric arc, and 
last longer. 

(3) The saving in energy consumption is 10 per cent., 
compared with the former arrangement. 

(4) Copper bus-bars can be used instead of cables. 

(5) The metal bath is heated more uniformly throughout, and 
the resulting product is more uniform. 

(6) Current interruptions, due to the rupture of the arc, are 
avoided, eliminating the resulting rushes of current on the 
motor-generator set, and allowing an easier melting of cold 
charges than with method B. 

(7) The consumption of the carbon electrode is more uniform, 
whereas with the former arrangement one side of the electrode 
was consumed more quickly than the other, resulting in greater 
expense for electrodes. 



1 Dr. A. Maeller, Stahl u. Eisen^ July and August, 1911, translated and 
slightly abstracted in Metall, and Chem, JSngineeringi November, 1911. 



GIROD ELECTKIO STEEL BEFININ6 FCRNAOE IS 



76 



ELECTKO-THERMAL METHODS 



Water-cooled Electrodes ; their Dangers and Losses. 

Dr. Mueller's article (see p. 74) also deals with the heat losses 
due to the water-cooling of the upper and lower electrodes, and 
with the supposed dangers of hearth-electrode cooling. This is 
the one special feature of the Girod type of furnace, which is 
most strongly criticised and condemned hy electrometallurgists 
and practical steel-makers, and it is interesting to find that 
Dr. Mueller, as the result of considerable practical experience, 
considers that these criticisms are unfounded. The following 
quotation from his article, proves this : — 

** Hearth-electrode cooling is still little understood and has even 
been called a great drawback to the efficient operation of the Girod 




!PiG. 36. — Arrangement of Electrical Connection to Furnaces. 

furnace. Fig. 37 shows, however, that only portions of the soft steel 
bars which project below the furnace body are cooled by water, the 
bars being connected by a common pipe-line. 

** The difficulties of maintenance of the lining of the Girod 
hearth are also often exaggerated. The dolomite hearth of the 
Gutehoffnungshiitte furnace rammed by compressed-air rammers, has 
lasted through more than 1,000 charges, and has never given any 
trouble, in spite of the different lengths of heats and the very different 
composition of the charges." 

Details are also given in Dr. Mueller's article of the calori- 
metric tests made to determine the heat losses with the water 
flowing from the cooling pipes around the positive and negative 
electrodes of the 8-ton experimental furnace. The losses were 
as follows :— 

Bottom steel electrodes 1*01 per cent, of total energy ; top 



GIROD ELECTRIC STEEL REFINING FURNACE 77 

carbon electrodes 8*65 per cent, of total energy supplied to the 
furnace. 

The running of this small experimental furnace has also 
thrown much light on the nature of many reactioQB in the 
refining of the steel. 

During the oxidation period, carbon is but slowly removed ; 
manganese more rapidly ; phosphorus very rapidly ; and about 20 to 
35 per cent, of the sulphur. 
The sulphur appears to be 
removed in three ways: — 
(1) During the oxidation 
period by the action of the 
iron oxide in the slags ; 
(2J during the deoxidation 
period by solution in the 
high lime slags ; and (3) 
by volatilisation as silicon 
sulphide. It has also been 
noted that oxides, slag 
emulsions and gases have 
a much more important 
hearing on the physical 
properties of the finished 
metal than the sulphur and 
phosphorus present.' 

Methods of Operating the 

Olrod Fnmaoe. Fm. 37.— Arrangement ot Water-cooling 

The molhodsof work- ^'I"" '" ^~"' °' """* ■^'"™«- 

ing the Girod Electric Refining Furnaces are very similar to 
those used in working the basic open-hearth furnace ; the 
method of obtaining deoxidation of the charge alone being 
different from that used in the open-hearth process of steel 
making. 

When the 3-ton furnace was charged with molten metal, it 
was found possible at the Gutehoffnungshiitte to obtain five 
tappings in twelve hours under favourable conditions, or eight 



78 ELECTEO-THEBMAL METHODS 

tappings (equal to twenty-five tons steel) in twenty-four hours, 
when working continuously. 

The best method of charging the electric furnace with molten 
metal from the open-hearth furnace is to run the metal directly 
into the former by means of a 28 ft. long spout, the weight of 
the metal being adjusted by the eye or by time. If a ladle be 
used and thid metal is weighed, much loss of heat occurs. The 
refining operation may be divided into two periods : — (1) 
oxidation period, and (2) deoxidation period. 

The first period is started by adding to the charge lime and 
iron ore. The proportion of these additions varies according 
to the chemical purity of the charge, and is determined 
in such a way that after complete melting, the bath shows 
approximately the following composition -.—Carbon, manganese 
and silicon less than 0*10 per cent. During this period of 
refining, oxidation is carried on vigorously, and the original low 
temperature of the bath favours a marked elimination of the 
phosphorus, practically all of which is removed before the 
slagging proceeds. 

A forging test will show whether the metal is in the extra 
soft state, and at this point, as soon as the temperature of the 
bath has become sufficiently high, the slag containing phosphorus 
and iron oxides is tapped oflf through the charging door by 
tilting the furnace slightly backwards. The first slag is 
immediately replaced by some lime, which clears the bath from 
the last traces of phosphoric slag. One slag is generally 
sufficient to remove all but traces of phosphorus. 
The Second or Deoxidation Period. 

The oxidising and cleaning slag being removed, a first 
deoxidation of the bath is effected by adding deoxidising agents 
such as ferro-silicon, or ferro-manganese, etc., these alloys being 
added in such proportion that they will not remain in. the bath. 

As regards the use of aluminium in the final stages of the 
refining operations, this metal is never employed alone as a 
deoxidising agent, but in the form of an alloy, with silicon, iron 



GIROD ELECTRIC STEEL REFINING FURNACE 79 

or manganese, or combined with all three in the form of ferro- 
mangano-silico aluminium. 

The bath is then rapidly covered with a slag consisting of 
about five-sevenths of lime, one-seventh of silica sand, and one- 
seventh of fluorspar, together with a slight addition of carbon, 
in the form of petroleum coke. During the second period (of 
deoxidation), care must be taken that the furnace is properly 
closed, the temperature being held sufficiently high to reduce the 
iron oxide in the slag. The reduction of the ferrous oxide in the 
slag is indispensable for the deoxidation and desulphurisation 
of the bath. Ferro-silicon and petroleum coke are employed 
to ensure complete deoxidation, and a slag should be obtained 
which disintegrates in the air into white powder. 

In order to facilitate the complete deoxidation of the bath, 
it is useful to add small quantities of silico-manganese, 
silico-manganese-aluminium, or even silicon-aluminium, these 
alloys acting very energetically upon the oxides in the 
bath, and forming a very fluid slag which easily mounts to the 
surface. 

During this same period, when the slag is completely 
deoxidised and is very basic, the desulphurisation, which was 
incomplete during the first stage of the operation, increases and 
is rapidly completed at the time of the tapping. Desulphurisation 
starts vigorously when the highly basic lime slag becomes white 
and readily fluid, ue,, after the removal of the metallic oxides. 
Carburising materials are eventually added for finishing the 
metal ; and a final addition of ferro-silicpn, ferro-manganeBe or 
other alloy, is made in order to arrive at the required composition 
of the steel. 

The following figures for the power consumption and working 
costs of the Girod Electric Refining Furnace are taken from 
detailed information supplied recently to the author, by the 
Soc. a, Electrometallurgique Procedes Paul Girod. The figures 
are based upon the practical experience obtained at Ugine with 
the Girod furnace. 



80 ELECTRO-THERMAL METHODS 

Power Consiunption and Working Costs. 

The power consamption was recorded at the terminals of the 
f amace and covered smelting, refining and finishing a charge of 
cold scrap. It amounted to 850 kw. hours for a 3-ton furnace, 
or 750 kw. hours for a 10-ton furnace. These figures, of course, 
varied with the composition of the charge and according to 
the quality and purity of the steel produced. 

The consumption of electrodes per ton of steel made was 
about 8 — ^9 kgs. for the 3 -ton furnace, and 8 — 10 kgs. for the 
10-ton furnace. 

Wages. — One smelter, one second-hand and one boy were 
required to operate the 3-ton furnace ; whereas one smelter, two 
second-hands and one boy, sufficed to operate the 10-ton 
furnace. 

Linings. — The furnace can be lined either with magnesite 
bricks or be tamped with a tarred magnesite, or dolomite. 
Dolomite tamped bottoms are now giving the best results. The 
work is done with heated hand-tampers, or with pneumatic- 
rammers. The durability of the lining is about 90 — 100 heats 
for the 10-ton furnace, and about 120 heats for the 3-ton 
furnace. At the end of that time the side walls and the hearth 
will need repairing. All the burnt or oxidised parts of the walls 
are scraped. The bottom is broken down about 10 — 15 cms. and 
is retamped with a new layer of dolomite, taking care to leave 
a passage open for the tops of the negative electrodes. This 
repair of the upper part of the bottom is the only one that 
requires a stoppage of the furnace, the damage to the walls at 
the slag line being repaired between the charging operations. 

The furnace roof is made of silica bricks and lasts on an 
average for 50 heats for the 10-ton furnace, and 70 heats for the 
3-ton furnace. 

The costs of Matenalsfor Slags, etc., varies considerably with 
the purity of the scrap used and with the quality of the steel 
required. Lime, ore, silica sand, fluorspar and petroleum -coke 
are all employed in the slagging process. The output of finished 



GIROD ELECTRIC STEEL REFINING FURNACE 81 



Table X. — Cold Charges. 



Raw Materials : 

Scrap, 1,100 kgs. at 75 frs. per 
1,000 kgs 

Slag ...... 

Deoxidising additions and recarburi- 
sation ...... 



Production Costs : 

Electric power, 850 and 750 kw 

hours at 2 centimes 
Electrodes at 32000 frs. per ton 

Wages 

Maintaining and repairs . 



Total cost per ton, francs. 



3-ton furnace. 



82-50 
230 

3-50— 88-30 



10-ton furnace. 



1700 

300 

300 
1200—3500 



12330 



82'50 
2-30 



^•W- 



oOl 



-88-30 



1500 
3-50 
150 
8-00-28-00 



116-30 



Table XI. — Molten Charges. 





3-ton furnace. 


10-ton furnace. 


• • 

Raw Materials : 






Liquid steel 4 per cent, loss in heat- 






ing, 1,040 kgs. at 80 frs. per ton . 


83-20 


83-20 


Slags 


2-00 


2-00 


Deoxidising additions 


3-50 88-70 


3-50 8^-71 


Production Costs: 






Electric power, 275 and 200 kw. 






hours at 2 centimes 


5-50 


400 


Electrodes 3 to 4 kgs. at 320 frs. 






per ton ..... 


1-25 


1-25 .' 


Wages, 8 heats in 24 hours 


1-00 


1-00 joOAflS 


Maintenance and repairs of the fur- 






nace 


400 11-75 


2-50—8-75 


Total cost per ton of steel, francs. 


100-45 


97-45 



E.T.M. 



G 



82 ELECTRO-THERMAL METHODS 

• 

steel runs from about 90 to 96 per cent, of the charged material, 
and depends chiefly upon the degree of oxidation of the latter 
before charging. When working with molten metal as charging 
material, the reduction of the working period per charge to 
two to two and a half hours leads to a great reduction in the 
total costs of the refining process. 

The estimates of costs on p. 81 are based on the Ugine 
results, and upon the conditions and costs of raw material, 
rate of pay, etc., obtaining in the S.E. District of France. 

These estimates do not include the expenses for ingot moulds, 
superintendence, testing, depreciation, and general charges, 
which vary too considerably to allow a good average to be 
established. 

It is interesting to compare with these latest official figures for 
the costs of refining cold steel scrap by the Girod furnace and 
process, the earlier estimates for the same process given by the 
present writer in the handbook already quoted (see p. 1). The 
working costs of the Girod furnace and process were given as 

follows : — 

£ s. d. 
Electric power, 1,060 kw. hours, at jd. perkw. hour. 12 1 
Electrodes, 10 kgs. at £4 3s. 4cZ. per metric ton . 10 
Maintenance charges . . . . .068 

Total per ton of steel . £19 7 

^^^^^-— ^— — 

Converting this total into francs and adding 8 frs. for labour 
we obtain a total of 40 frs., as compared with 35 frs. and 28 frs. 
tor the latest estimates. The chief reduction is in the electrical 
energy required to operate the 3-ton furnace. This has been 
brought down from 1,060 kw. hours to 850 kw. hours, a reduction 
of 20 per cent. 

The cost of the 2 — 3 -ton size of Girod furnaces is 
approximately ^6600 ($3,000). This furnace will require a 
300 kw. generator to provide the energy. This energy may be 
supplied in the form of single-phase current, 4,600 — 5,000 
amperes at 65 — 75 volts. 



GIROD ELECTEIC STEEL EEFINING FURNACE 83 



As regards the quality and chemical composition of the steel 
made in the Girod furnace, the following figures, taken from 
various sources, show that remarkably pure steel can be produced 
by this furnace and process : — 

Table XH. 

Average composition of the scrap material used, and of the refined 
metal produced at the Ugine Electric Steel works. 



Scrap Material. 



Carbon . 
Silicon . 
Manganese 
Sulphur 
Phosphorus 



•35 per cent. 

•20 

•70 
•095 
•095 






Finished Steel. 



Carbon from '04 to '60 per cent. 
Silicon . . '20 per cent. 
Manganese . '30 
Sulphur . 015 
Phosphorus . '015 



ty 



»> 



Table XHI. 
Composition of the various brands of steel produced.^ 



No. 


Properties. 


Carbon. 


Silicon. 


Man- 
ganese. 


Sulphur. 


Phos- 
pliorus. 


other 
constituents. 


1 


Very soft 


0079 


106 


0-205 


0016 


0-012 




2 


Soft . 


0-236 


0-180 


0-431 


0-012 


0-010 




3 


Middle soft . 


0-283 


0-208 


0-430 


0014 


0-010 


__ 


4 


Middle hard . 


0-388 


0155 


0-342 


0-011 


0-009 


_. 


5 


Middle hard . 


0-463 


0-204 


0-463 


0010 


0016 


__ 


6 


Hard 


0-596 


0-198 


0-302 


0017 


0005 




7 


2 % Nickel . 


0076 


0-099 


0-101 


0-014 


0010 


2-12 % Ni 


8 


3 % Nickel soft . 


0-06 


0123 


0-209 


0013 


0-007 


3-47 % Ni 


9 


3 % Nickel hard . 


0-364 


0-144 


0-435 


0-012 


0015 


3-41 % Ni 


10 


6 % Nickel soft . 


0-134 


0-148 


0376 


0-016 


0-013 


6-25 % Ni 


11 


5 % Nickel middle 














soft . 


0-250 


0-157 


0-414 


0-010 


0-015 


5-08 % Ni 


12 


Nickel-Chrome 


0-420 


0-199 


0-500 


0-010 


009 


( 26-63 % Ni 
( 0-77 % Cr 


13 


Tool steel 


1-223 


0-168 


0-224 


0-011 


0010 




14 


Ditto . 


1-474 


0-199 


0-264 


0-015 


0-007 




16 


Ditto 


1010 


0-219 


0-306 


008 


0009 


0-32 % Cr 


16 


Ditto 


1-277 


0-230 


0-130 


0-009 


0-006 


0-24 % Cr 


17 


Ditto . 


1-251 


0-176 


0-268 


0-010 


0-008 


( 1-21 % Cr.; 
\ 0-49 % Ni 
( 0-07 % Cr 


18 


Ditto . 


0-689 


0-029 


0-096 


0-012 


009 


0-46 % Mo 
(26'82 % W 



Mining Journal, November, 1909. Dr. W. Botchers. 



a2 



84 



ELECTEO-THEEMAL METHODS 



Physical tests of the steel produced in the Girod furnace show 
that it possesses special qualities of a high order, namely, the 
approximation of the limit of elasticity to the breaking stress 
and high resilience. Tests of three classes of steel made in the 
Girod furnace were given by J. A. Seager in the Journal named 
below/ and are reproduced here in Tables XIV., XV., and XVI. 



Table XIV. 



Treatment. 


Elastic 
limit, lbs. 
per sq. in. 


Maximum 
stress, lbs. 
per sq. in. 


Elongation, 
per cent. 


Con- 
traction, 
per cent. 


Resilience 
lbs. 


Annealed at 900° C. 
Hardened at 800° C. and 
tempered at 600° C. . 


39,241 
41,887 


60,486 
63,051 


33 

28 


73 
76 


1,034 
1,100 



Table XV. 



Treatment 


Elastic 
limit, lbs. 
per sq. in. 


Maximum 
stress, lbs. 
per sq. in. 


Elongation, 
per cent. 


Con- 
traction, 
per cent. 


Resilience, 
lbs. 


Soft SteeL 
Annealed at 900° 0. 
Hardened at 800° C. and 
tempered at 600° C. . 


41,887 
64,374 


68,862 
76,940 


31 
22 


60 

74 


94-6 
106-6 


Medium Soft Steel 
Annealed at 900° C. 
Hardened at 800° C. and 
tempered at 600° C. . 


44,763 
41,005 


71,429 
86,861 


29 
21 


60 
66 


72-6 
77-0 


Medium Hard Steel, 
Annealed at 900° 0. 
Hardened at 800° C. and 
tempered at 600° 0. . 


67,319 
91,049 


92,372 
113,316 


21 
14 


34 
37 


26-4 
35-2 


Hard Steel 
Annealed at 900° 0. 
Hardened at 750° C. and 
tempered at 600° C. . 


60,185 
114,859 


97,884 
137,126 


17-5 
9 


30 
30 


19-8 
264 


Very Hard Steel 
Annealed at 800° C. 
Hardened at 750° C. and 
tempered at 600° C. . 


66,917 
111,993 


113,316 

142,858 


16 
9-5 


30-6 
49 


19-8 
26-4 



1 Iron Trade Review^ June 3rd, 1909. 



GIEOD ELECTRIC STEEL REFINING FURNACE 85 



Table XVI. 



Treatment. 


Elastic 
limit, lbs. 
per sq. in. 


Maximum 
stress, lbs. 
per sq. in. 


Elongation, 
per cent. 


Con- 
traction, 
per cent. 


Resilience, 
lbs. 


1 . Air hardened at 860° 0. , 

tempered at 600° C, 
and cooled very slow- 
ly in furnace . 

2. A ir hardened at 860° 0., 

and tempered at 
400° 0. . 

3. Air hardened at 860° 0. 


114,869 

160,936 
216,932 


121,693 

167,990 
231,042 


16 

11 

8 


55 

48 
38 


46-2 

330 
220 



Table XIV. represents the tests for an average quality of steel, 
Table XV. tests of carbon steels, and Table XVI. gives the tests of 
the special K.N.A. steels, of which the chemical composition is 
not revealed. 



Description of Notable Installations of the Oirod Fnmace. 

In closing this description of the Girod electric steel refining 
fnmace and process, some details of the more notable installations 
of the same may be given. 

The Works at Ugine, Hie, Savoie, are the property of the Soc. 
des Forges et Acieries illectriques Paul Girod ^ a company floated 
in 1909, with a capital of 4,000,000 frs., which has since been 
increased to 12,000,000 frs., to take over the electric steel 
furnace patents of Paul Girod. 

The electric power utilised at this steel works is derived from 
three generating stations situated in the valley of the River Arly 
(a tributary of the Eiver Isere) providing 6,000 h.p. ; in the 
valley of the Dorion (a tributary of the Arly), providing 
4,000 h.p. ; and in the valley of the Bonnant (a tributary of the 
Arve), providing 11,000 h.p. The power is transmitted to 
Ugine, a distance of 45 kms., as three-phase current at a pressure 
of 45,000 volts. The total energy available fluctuates between 
18,000 h.p. and 36,000 h.p. A general view of the steel works 
at Ugine is shown in Fig. 38. 



86 ELECTRO-THERMAL METHODS 

The furnace and casting bouse contaioB at present seven 
turoBces, ranging from J ton to 12 tons capacity per charge. 
The furnace house is provided with four travelling cranes, and 
is designed to contain sixteen furnaces and to produce 200 tons 
of steel per day. The smaller furnaces produce the special 
alloy and high-prieed steel, the large furnaces the high carbon 
and nickel steels. The works is complete with annealing shop, 



Fio. 38.— General View ol Ugine Steel Works. 

machine shop, forging department, tempering shop and rolling 
mills, and was the first successful steel works to be operated 
throughout by electricity. 

Oehler it Co., at Aarau, Switzerland, are manufacturers of steel 
and iron eastings for engineers. They have replaced their 
crucible steel plant by a 2-ton Girod furnace, and since August, 
1908, have been obtaining most satisfactory results from the 
latter. Power is obtained from the Aarau City Electricity 
Station, which has developed between 8,000 and 4,000 h.p. from 



GIROD ELECTRIC STEEL REFINING FURNACE 87 

a fall on the River Aar, and sells current for smelting purposes 
at 8 to 4 centimes per kw. hour. 

Charges of about 1,500 kgs. are prepared in this furnace at 
Aarau, using a current of 8,500 amperes at 55 volts. Ninety- 
eight per cent, of all the castings obtained are good, the average 
tensile strength of the cast metal being 55 — 65 kgs. per sq. mm., 
with an elongation of 5 — 10 per cent. 

The Gutehoffnungshutte at OberhauseUy in Germany^ have had 
a 8-ton furnace installed in their No. 1 Martin Steel Works since 
1910. The furnace operates with single-phase current of 6,700 
amperes at 75 volts, furnished by a motor generator of 500 kw. 
capacity. The products of this furnace are carbon steels of 
various degrees of hardness, alloy steels, and special steels for 
tools, engine-cranks, axles, etc. 

The Simmonda Manufacturing Co,, of Fitchburg, U.S.A., manu- 
facturers of saws and machine-knives, have installed a 8 -ton 
Girod furnace in the crucible steel department of their Chicago 
works. The results of the trials of this furnace for melting the 
best brands of Swedish bar and for producing steel for their 
ordinary requirements will determine whether an installation of 
larger electric furnace of the Girod type will be adopted for the 
new works this Company are about to erect at Lockport, New 
Jersey. 

The Bethlehem Steel Co., of U.S.A., has decided to adopt the 
Girod furnace and process for producing the higher grade steels 
required in its foundry, and an order has been placed for a Girod 
furnace of 10 tons capacity. 

Future Developments of the Oirod Furnace. 

The Girod type of furnace in the 2 — 4 tons size is especially 
adapted for refining the high-class steels intended for fine castings 
and for the manufacture of special alloys. Its high temperature, 
smooth working, and uniforruity of product are all points in its 
favour for this class of work. 

The experience gained with the larger sizes of furnace seems 



88 ELECTRO-THERMAL METHODS 

to indicate that the maintenance of the lining of the furnace 
bottom is likely to prove a troublesome matter, owing to the 
necessity for preserving openings in it for the negative electrodes. 
On this account the writer does not expect to see the Girod type 
of furnace employed for the production of structural steel or of 
rail steel, which demand large units and low producing costs. 

In its own special field, however, the Girod steel-refining 
furnace would appear to have a promising future before it, and 
the number in use will no doubt be rapidly increased as the 
good points of the furnace become better known and appreciated. 



CHAPTEB VI 

THE STASSANO EIjECTBIC STEEL FUBNACE AND PROCESS 

Major Ernesto Stassano, of the Italian Army (Artillery),- 
appears to have been the first electro-metallurgist to apply 
electric heating on a practical scale to the smelting and refining 
of iron and steel. 

Stassano's first English Patent, No. 11604, describing an 
electrically-heated furnace for producing steel direct in one 
operation from iron ore was taken out in 1898, and experi- 
mental trials were commenced with this furnace at Bome in 
1899. Fig. 39 shows a sectional elevation of this earliest 
form of steel-smelting furnace. Although this design was soon 
discarded by the inventor, it is interesting to note that it closely 
followed the blast-furnace form, and that this type of furnace has 
been copied in the successful electric iron-smelting furnaces of 
Gronwall and Heroult, now operating in Norway and in California 
(see Chapter III., p. 27). Stassano's early attempts to produce 
steel direct from the ore in one operation were doomed to failure 
for the reasons given in Chapter III., and the trials of the 
process and furnace at Darfo in Northern Italy in the years 
1900 — 1902, led to no practical or financial success. 

The Italian Government became interested however in the 
furnace, and instituted trials of the same for refining the special 
brand of steel used for manufacturing shells and ammunition at 
the Eoyal Arsenal, Turin, the first 250-kw. Stassano furnace 
being erected here in 1903. 

Since that year the Stassano electrical method of refining 
mild steel used for shells has been in continuous operation by 
the Italian Military Authorities at Turin. A new company, the 
Forni-Termo-ellettrici Stassano, was also formed in 1905 to take 



90 ELECTBO-THERMAL METHODS 

over the assets of the earlier company, and an electric steel 
'works 'was planned and partially erected at Turin. Ihia works 
was equipped vith six furnaces ranging from 100 h.p. up to 
1,000 h.p. capacity, and produced chiefly steel-axles for railway 
carriages, waggons and motor-cars. The venture was not a 
financial saccess, and in 1909 one portion of the electric furnace 
plant was transferred to the works of the Elba Company at 
Portoferraio, and the remainder to the works of the Milan Steel 



Fio. 39. — The Staaeano Furnace, earliest form. 

Company. In the light of the latest developments of electric 
steel refining, it would appear that this early attempt to run a 
steel works entirely by electricity was somewhat premature, and 
that even to-day, with seven years additional experience of 
electric steel refining at one's command, there are comparatively 
few places in the world where a similar undertaking could be 
carried on with commercial success. 

The Stassano electric steel-refining furnace has proved most 
successful when used (in the 250-kw. size) as a refining and 
melting furnace in steel foundries where small and intricate 



STASSANO ELECTEIC STEEL FUENACE 91 

castings are made and form the chief portion of the output. A 
large number of these small furnaces, producing 1 ton of steel 
per charge, are now at work, or in course of erection, in various 
parts of the world. 

The power consumption of the Stassano furnace per ton of 
steel produced, according to the published figures, would appear 
to be higher than that of the Heroult and Girod types, and 
although in the smaller furnaces this disparity is not of great 
importance, on account of the higher selling value of the steel 
castings produced, it becomes a considerable handicap when the 
cheaper varieties of rail and constructional steel are to be manu- 
factured. Owing to the higher power consumption per ton of steel 
produced, the 1,000 h.p. Stassano furnaces which were erected at 
the Forni-Termo-ellettrici Stassano works at Turin did not 
prove very successful and, so far as the writer is aware, no 
Stassano refining furnace of this size is now under construction. 
As regards the smaller furnaces, between ten and twenty are in 
operation or in course of erection in the leading steel-pro- 
ducing countries, and some details of this type of furnace will 
now be given, together with tests of the steel produced, estimates 
of working costs, and information (so far as this is available) 
concerning the steel works where this type of furnace is in use. 

The Stassano Rotary 200 h.p. Fnmace (First Form). 

This furnace was of the arc type. The special feature which 
differentiated it from all other electric arc furnaces for iron and 
steel refining was the use of the rotary principle in order to 
obtain a better mixing of the charged materials and a more 
uniform heating effect. This design is protected by English 
Patent No. 8288 of 1902, and the following description was given 
by the inventor himself in an article published in 1908 in the 
Journal named below.^ 

Figs. 40 and 41 show diagrammatically that the rotary 
electrical furnace consisted of a sheet-iron cylinder with a conical 

1 Electro-chemical and Metallurgical Industry^ August, 1908. 



ELECTRO-THERMAL METHODS 



root, lined on the inside with refractory material. The melting 
chamber was aUo cylindrical, with a cupola of fire-brick. Suit- 



STASSANO ELECTRIC STEEL FURNACE 93 

able openings were provided for the electrodes, which projected 
towards the centre of the furnace, their ends being at proper 
distances from each other for the formation of the arcs, and at 
a convenient height above the bottom. 

The electrodes were protected on the outside by water-cooled 
cast-iron cylinders fitted to the mantle of the furnace. The 
movement of the electrodes was controlled by guide-rods fitted 
outside the furnace. To the end of the carbon electrodes a 
metallic rod was attached, the end of which was connected to a 
flexible cable leading beneath the furnace to the slip-rings for 
current supply. 

Above each of the water-cooled cylinders which protected the 
external portion of the electrodes, a small hydraulic pressure 
cylinder was provided ; the piston rod of this was connected with 
the metallic rod of the electrodes, and thus controlled the move- 
ment of the electrodes and regulated the distance between 
their terminals within the furnace. 

The lower part of the furnace, somewhat above the bottom, 
was surrounded by an L-shaped rail of cast-iron running upon 
conical rolls. Below the rolls there was another cast-iron rail, 
resting on the inclined top of the pit-wall and forming the 
support of the furnace. The longitudinal axle of the furnace 
was, therefore, inclined by a certain angle against the vertical. 

The furnace was revolved by means of a strong gearing at the 
bottom. Insulated copper rings were attached to the head wheel, 
which by means of copper bars and the above-mentioned elastic 
cables, transmitted the current to the electrodes. The current 
was supplied from the generator to a series of brushes, disposed 
round the top of an iron support in the centre of the pit and 
cables. These brushes and slip-rings maintained continuous 
connection between generator and electrodes during the rotation 
or standstill of the furnace. Besides the brushes, there was a 
distribution valve, mounted on the top of the stationary iron 
support, which distributed the water for the pressure regulators 
and also for the cooling cylinders protecting the electrodes. 



94 



ELECTRO-THERMAL METHODS 



The discharge was at the bottom of the melting chamber ; 
opposite to it another opening was left for charging. In the 
centre of the brick cupola an exit was provided for the volatile 
products of the furnace reactions. Through this exit the gases 
escaped into a metal tube shut by a sand valve, and leading to a 
vessel filled with water, from which the gases might escape into 
the open air. This arrangement prevented air entering from the 
atmosphere into the melting chamber. No air could enter by the 
charge or discharge holes, since the pressure inside was higher 
than outside. 

It was claimed by Stassano that this design fulfilled satis- 
factorily the three essential conditions of good work in electric 
steel refining, namely, (1) a neutral atmosphere in the melt- 
ing chamber, (2) highest possible arc temperature, (3) good 
admixture of the molten materials without contact with the 
electrodes. 

The following figures, based on the practical results obtained 
with the 200 and 1,000 h.p. rotary furnaces at Turin, show the 
average power consumption and output per charge for the 
different classes of steel produced : — 

Table XVH. 





Power Consamption. 


Output. 


200 fe.p. Furnace : 






Steel for projectiles 
Mild steel for castings . 


1,250 kw. hrs. per metric ton 
1,260 „ „ 


653 kgs. 
730 „ 


1,000 /i.p. Furnace : 






Steel ingots for pro-l' 
jectiles . . . [ 


958 ,, „ „ 
918 „ „ 


3,900 „ 
3,900 „ 



The percentage of the scrap recovered as steel in the 
Stassano type of furnace is unusually high, owing to the exclusion 
of air from the melting chamber, and consequent absence of any 
loss from oxidation during the refining process. In melts where 



STASSANO ELECTEIC STEEL FUENACE 



95 



the charge and output have been weighed, the loss due to 
oxidation was only 1 J per cent. 

As regards the cost of working, the trials at Turin yielded the 
following figures per ton of steel produced : — 



Table XVHI. 



Electrodes 10 kgs. 
Refractory materials . 
Wages for three men . 
Water for cooling purposes . 



£ 8, d. £ 8, d, 

2 6 

8 Oi to 12 1 

9 11 
6 



£1 llj to 1 5 



An estimate based on the results obtained at an installation 
at Bonn, in Germany, gave the following figures : — 

Table XIX. 

Per metric ton 
of cast steeL 

£ 8, d» 

1. Raw materials, including addition of chromium 

to finished steel 3 9 5 

2. Electric power (1,000 kw. hours at '536 penny per 

kw. hours) 2 4 8 

3. Refractory materials for linings . 

4. Labour 

5. Interest and depreciation . 

6. Electrodes .... 

7. Water for cooling purposes 



The New Form of Stassano Furnace. 

The new Stassano furnace combines the advantages of both 
the rotary and tilting type, and is protected by English Patent 
No. 8901 of 1911. The following description is based on that 
given in the Patent Specification:— 

The furnace comprises a casing of sheet-iron or other 
material, enclosing a melting chamber A (Fig. 42) of re- 
fractory material. This chamber in the case of small furnaces 
has the form of a hollow sphere, with the lower portion cut away 







11 


10 









9 


11 









4 


11 









2 


6 






, 





6 






£7 


3 


9 



96 ELECTRO-THERMAL METHODS 

by a plane constituting the bottom o( the furnace. In fnrnaces 
of large dimensions, the interior cavity has preferably the form 
of an ellipsoid, with the bottom similarly cut away in the lower 
portion. This form of furnace chamber hag the advantage that 
the walls of refractory material are rendered more resisting, and 
can be reinforced by a filling or envelope B of refractory earth. 
At the same time, the chamber serves to reverberate better the 
heftt emanating from the arc or arcs. 

After describing the system of electrode arrangement and 
control which follows closely that of the earlier furnace, the 
Patent Specification 
describes the special 
feature of the new 
furnace in the follow- 
ing terms : 

The mounting of the 
furnace is effticted as 
follows : — 

At two diametrically 
opposite points of the 
casing (see Figs. 42 and 
43), are two pivots (D) 
mounted in two sup- 
ports (E) rigidly con- 
nected with a ring encirchng the casing, and having two pivots (G) 
arranged at an angle of 90" with respect to the pivots (D). The 
pivots (Q) are supported by the standards, which are connected 
together by a stirrup passing below the bottom of the furnace. From 
the method of construction it is apparent that the furnace chamber 
is so suspended that its vertical axis can assume any inclination to 
the vertical. The casing (C) has projecting from its lower end a 
pivot (H) the axis of which coincides with that of the casing. The 
end of this pivot is rounded, and has a bearing in a groove or 
socket formed in a member (K) adjustably mounted on a spoke of 
a wheel (L) journalled on the stirrup. The wheel (L) can be rotated 
by any suitable means, as for example, by means of teeth on its 
periphery engaging a pinion (M) operated by means of a shaft and 
worm gearing, driven by a small electric motor. By turning the 



Fig. 42.- 



STA8SAN0 ELECTRIC STEEL FURNACE 



97 



wheel (L) on its axis the pivot (H) is displaced in a circle, so that 
the axis of the furnace traces out a cone with a circular base. 
This movement, by reason of the double suspension of the chamber, 
imparts a rotative movement to the molten mass contained in 
chamber (A), which movement may be continuous or intermittent, 
corresponding to the motion of the wheel ' (L). The wheel can, if 
necessary be turned alternately first in one direction and then in 
another. By this method of suspension, the furnace body oscillates 
simply on the points (D) and (C), and can be subjected at will, either 
to a rotary or to a tilting movement. 

Figs. 44 and 45 show the older type of furnace installed at the 
Royal Arsenal, Turin, Italy, and Figs. 46, 47, and 48 are photo- 




\r 


a 




6o. o 




Fig. 43. — ^The Stassano Eotary Furnace, latest form (plan). 

graphs of the new rotary furnaces, taken at the works of the 
Electroflex Steel Company, Newcastle, England. 

No figures have yet been published showing the power con- 
sumption or costs of operating this new type of furnace. No 
doubt these figures will soon be available ; for two furnaces of 
this type have been erected at the works just named during 1912 
also one in Bussia and another in Austria. 

As regards the total number of Stassano furnaces now 
operating, a comparative table of the Electric Furnaces in opera- 
tion compiled by the Grondal-Kjellin Company in 1909, gave thQ 

E.T.M. H 



98 ELECTRO-THERMAL METHODS 

number of Stassano furnaces at that date as eleven, and the aggre- 
gate tonnage capacity as 16"90 tons steel per day. If we odd to 
this total the five furnaces referred to above, we obtain a total o! 
sixteen furnaces, with a daily capacity of 2i tons of finished 
steel. These may be seem small totals, in comparison with the 
figures for the Heroult and Girod furnaces given in Chapters IV. 



Fio. 44.^The StasBano Botaiy FurDEce (2oO h.p.) at the 
Royal Arsenal, Turin. 

and V. ; but as already explained, the Stassano Rotary furnace 
has been found most satisfactory in the small-sized units, pro- 
ducing only 1 ton of steel at each tapping operation ; and 
the aggregate capacity of the sixteen furnaces now operating is 
therefore bound to be small. 

As proof of the opening which now exists in Europe and 
America for small electric furnaces in foundry work, the follow- 



STASSANO ELECTRIC STEEL FURNACE 99 

ing extracts from speeches delivered at the Fifteenth Annual 
General Meeting of the American Electro-chemical Society during 
& general diBcussion upon the Electrometallurgy of Iron and Steel, 
are not without interest. 

" We have some 6,400 foundries in North America, and very many 
of these are looking seriously into the production oE small steel 



Fig. 45.— The Stassano Eotary Furnace (260 h.p.) at the 
Eoyal Arsenal, Turin. 

castings. I would recommend that our members take up the matter 
seriously and in such a way that with a minimum of first cost and 
disturbance in an existing establishment, a small electric plant can be 
installed and operated, using only steel scrap and billets, preferably 
preheated by means other than electric — say the soaking pit, or 
regeneration of gas and air." K. Molderike} 

" I have had a great many inquiries from foundrymen throughout 
1 Tramacttortt of the Amer. Electro-ckem. Society, Vol. XV., pp. 253 — 254. 

Ha 



100 ELECTRO -THERMAL METHODS 

tlie country as to how they could mnke tlieir own ateel castings to fill 
a wide variety of apeeifi cat ions, and in many cases the expense was 
almost a negligible quantity. The proposition was to be able to get 
delivery and to get quality. Those two elements were demanded, and 
a tonnage, in some cases, not to exceed 1,000 lbs. In many cases 
they want to make a comparatively short campaign in each one. If 
some process can be developed which will enable a manufacturing 
concern itself to make its own steel castings to fit in with ita equipment, 
that is, fit the equipment it is manufacturing as it wants them, there will 



be a demand for them. If the process will utilise waste material about 
the plant, that is, iron borings, ateel borings and such material as that, 
so much the better, and every plant has quantities of that kind of 
material. It has seemed to me for a long time that the electric furnace 
was a solution of the problem." H. M. Lane.'^ 

The following are details of individual installations : 
Bonner Fraser Fahrik, Bonn-on-Rhine, Germany. — A 250 h.p. 
furnace of the older type was installed here in 1908. This 
furnace is operated by three-phase current supplied from the 
' Traneactwng of the Anier. EleetTO-ckem. Society, Vol, XV., pp. 253 — 354. 



STASSANO ELECTRIC STEEL 'FimNACE' 101 

generating station ot the Berggeist-Briihl Electricity Worka. 
The carrent is supplied at a pressure of 5,500 volts ; this is 
reduced to 100 volts between the two phases by a transformer 
placed near to the furnace. The cost of the current at the 
furnace terminals is '536 penny per kw. hour. The raw materials 
used at this works are usually cuttings, turnings and Bcrap, 
costing from £2 19e. 6d. to £S is. 5d. per metric ton. Three and 



Fio. 47. —The Stassano Fumacea and Castlog Shop at the Works of the 
Electro-Flex Steel Co., Newcastle, England. 

a half hours are required to produce complete fusion, and a 
further one and a half hours for the refining operation, equal to 
five hours per charge as poured. The entire charge of fused 
metal is poured at once and is used for fine steel castings, the 
usual composition of the refined metal being carbon '08 to 
'18 per cent., sulphur '03 per cent. ; phosphorus 'OC per cent. 
Occasionally castings of tool steel are produced, containing "70 



102 ' " ELECliiO-THEEMAL METHODS 

to 1*80 per cent, carbon, with or without the additioD of nickel, 
chromium, or tungsten. 

The " Elba " Company at PoTtoferraio. — This Company has 
taken over two of the Stassano furnaces operated earlier by the 
Stassano Electric Furnace Company at Turin, and according 
to Catani ' had been working these furnacee with cold charges. 
The " Elba " Company, however, possess both a smelting 



Pie. 48. — The Stassano Furnaces at Newcastle (diBcharging). 

works and a Bessemer-steel plant at Fortoferraio, and it is 
more than probable that liquid charging of the Stassano 
furnaces, in accordance with the most modern development 
of the electric steel refining process, has been adopted at this 
works. 

The Stassano Electric Furnace Company. — Although this 
Company was not a financial success, some details of the 
equipment of the works at Turin may not be out of place 
here. The works were supplied with three-phrase current at 

' See paper read before the Iron and Steel Institute in London, in October, 1911. 



STASSANO ELECTRIC STEEL PURNACE lOS 

21,500 volts, by the Societa Anonima Elettricita Alta Italia, 
and the current pressure was then reduced by special trans- 
formers to the voltage required for working the furnaces. 
The six furnaces were of the following sizes and type: — 



Horse-power. 


Current, 


Voltage. 


Amperes. 


2 at 100 . 
2 at 200 . 
2 at 1,000 . 


Single-phase 
Three-phase 
Three-phase 


75 
100 
150 


1,000 

900 

2,700 



The current supplied to the Steel Company varied between 
350 kw. and 800 kw. (between 20 and 42 per cent, of the 
total capacity of the furnace plant). The steel castings produced 
were used chiefly for railway and automobile constructive work. 

Weicheisen-Stahlgiesserei L. Gasser at St. PolteUy in Austria. 
— This steel works has operated a 250 h.p. Stassano furnace of 
the older type since September, 1909. The current supply is 
taken from the distribution system of the Elektricitatswerk, 
St. Polten, and no difficulty has been experienced in running the 
furnace in parallel with the town's lighting and power systems. 
The raw material used for charging the furnace consists of 15 per 
cent, of hard steel scrap and the remaining 85 per cent, of 
wrought iron turnings, etc. During the early trials of the furnace 
the power consumption averaged 1,010 kw. hours per ton of 
material charged. No doubt this figure has been reduced as 
more experience has been gained in the use of the furnace, but 
no later figures are available for publication. 

As regards other installations, the Societa Elba has one 
1,000 h.p. at its works in Liguria, Italy ; the Fonderia Milanes 
d'Acciaio has two 100-h.p. and one 250-h.p. furnaces in operation 
at its works in Milan ; and at Odessa, in Bussia, the steel foundry 
of J. J. Hoehn has two 250-h.p. furnaces of the new type, either 
in course of erection or in use. The Italian Navy yard is also 
about to adopt the Stassano furnace and process. 



104 



ELECTRO-THERMAL METHODS 



Chemical and Physical Tests of the Stassano Steel. 

Catani, in the paper read before the Iron and Steel Institute 
in October, 1911,^ has given a large number of tests of Stassano 
steel, and from the tables given in that paper the following 
figures have been taken: — 

Table XX. 
200 H.P. Rotating and Tilting Furnace, pboducing a Soft Steel for 
Castings. Averages of a Large Number of Tests with Different 
Charges. 

Chemical Tests. 



Per cent. 


Per cent. 


Per cent. 


Per cent. 


Per cent. 


•235 C 
•207 C 
•360 C 


•195 Si 
•236 Si 
•140 Si 


•047 S 
•043 S 
•052 S 


•031 P 
•027 P 
•036 P 


•546 Mn 
•421 Mn 
•486 Mn 



Physical Tests of the 


Same Stefja. 


No. 


Tensile strength, 
in kgs. per sq. mm. 


Elongation, 
per cent. 


1 
2 
3 


(Average) 43' 5 
(Average) 41*2 
(Maximum) 45 '0 


18-2 
19^0 
19^4 



The following are the average test results of steel made in the 
1,000-h.p. furnace and intended for projectiles : — 

Table XXI. 
Chemical Tests. 



No. 


Per cent. 


Per cent. 


Per cent. 


Per cent. 


Per cent. 


1 

2 


•310 C 
•450 C 


•242 Si 
•061 Si 


•037 S 
•039 S 


•023 P 
•029 P 


•877 Mn 
1-211 Mn 



TraTisactions of Iran and Steel Institute^ October, 1911. 



STASSANO ELECTRIC STEEL FURNACE 105 



Physical Tests of the same Steef,. 


No. 


Tensile Strength 
in kg. per sq. mm. 


Elongation, 
per cent. 


1 
2 


58-0 
70-0 


21-4 
170 



In conclusion, the following analyses of special steels, made 
in the newer type of rotating and tilting 200-h.p. furnace may 
be given : — 

Table XXIL^ 



Nickel Steel 
Tungsten Steel . 

High Speed Steel | 



Per cent. 


Per cent. 
Carbon. 


Per cent. 
Silicon. 


Percent.' 
Sulphur. 


Per cent. 
Phos- 
phorus. 


6-60 Ni 
1^66 W 
1^27 W 
3-50 Cr 


•180 
•960 

1 1-66 

4 


•123 
•123 

•062 


•048 
•018 

•012 


•007 
•018 

•010 



Per cent. 
Manganese. 



•780 
600 

■979 



Note on Working of Stassano Furnaces in U.S.A. 

Schmelz, of Detroit, reports^ that the power consumption of 
the latest design of Stassano furnace is lower than the figures 
hitherto published. He himself has obtained two successive 
charges from one of these furnaces with power consumptions of 
787 and 810 kw. hrs. per metric ton respectively, while the 
average over a long period of time for this furnace was only 
900 kw. hrs. These figures are for cold charges. 



^ More recent tests of Stassano electric steel will be found in the Appendix, p. 232. 

2 Iron Trade Review (U.S.A.), December 5th, 1912. 



CHAPTER VII 

THB EJELLIN AND ROCHLING-RODBNHAUSEB STEEL REFINING 

FURNACES 

The furnaces described in the preceding chapters of this work 
have all been of the arc or of the combined arc and resistance 
type. We have now to consider furnaces of the third class (see 
Chapter II. p. 10). Of these the Kjellin and Rochling-Roden- 
hauser furnaces are the most important, for the latest available 
figures show that ten of the former and seventeen of the latter 
are now actually operating, or are under construction, in Europe 
and America. A list of these furnaces, with details of their 
capacity and methods of charging, is given in the Appendix. 

The largest furnace is installed at the Bochlingische Eisen u. 
Stahl Werke at Yolklingen, and is of the Bochling-Bodenhauser 
type with a working capacity of 12,000 kgs« Other large 
furnaces of the same type are to be found in Germany, at the 
works of the Bergische Stahlindustrie at Bemscheid, and also 
at the works of the Eicher Hiittenverein, Le Gallais Metz & Co., 
Dommeldingen. 

As already indicated in Chapter II., the general principle of 
the induction furnace is to use the metal as the secondary 
circuit in a furnace which is practically a step-down transformer. 
The original type of Kjellin furnace was patented in the United 
Kingdom in 1900, and is shown in Figs. 49 and 50, the 
primary coil being shown at DD, and the ring of molten metal 
forming the secondary circuit at BB. The primary is supplied 
with alternating current. The intensity of the induced current 
in the secondary circuit of molten metal can be calculated 
roughly by multiplying the amperes of the primary current by 



THE KJELLIN AND ROCHLING-RODENHArSER 107 

the number of turne contained in the coil. The method of work 
18 as follows, 

About 1,000 kgs. of molten pig-iron or scrap steel are poored 
into the annnlar ring BB of the furnace, and the current is 
switched on to the primary coil. A current of 90 amperes at 
8,000 rolts is utilised ; this is transformed in the secondary to 



Fig, 49.— The early type of Kjellin Furnace {elevation). 
a current of 30,000 amperes at 7 volts. Eight hundred kilograms 
of cold pig-iron and scrap steel of the required composition, and 
in calculated proportions, are now added to the molten metal 
in BB, the covers of which are made in short segments, in 
order to allow of this addition taking place equally all round the 
ring. The covers are now replaced, and the heating is con- 
tinued for four to six hours with different fluxes, until the metal 
has attained the degree of parity desired. The plug is then 



108 ELECTRO-THERMAL METHODS 

removed from the tapping hole, shown on the left of Fig. 49, 
and from 800 to 1,000 kgs. of the metal are run off and cast into 
ingots. The remaining 800 kgB. are left in the furnace to carry 
the current until fresh raw materiale are added. It is found that 
there is always less carbon in the finished steel than is con- 
tained in the charged raw materials, while the silicon has 
increased. Two runs made with this furnace at G-jsinge, in the 



Fig. 50. — The early type of Kjellin Furnace (plan). 

early days of the electric steel industry, gave 1,985 kgs. of steel 
with a power expenditure of 1,851 kw. hours in 12f hours. The 
average power consumption was therefore 932 kw. hours per 
metric ton of 2,204 lbs. The raw materials in each case were 
best Swedish pig-iron and Wallon bar-iron, with scrap steel 
from previous charges. The steel produced contained only "008 
per cent, sulphur and -OlO per cent, phosphorus, with '417 per 
cent, carbon in one case and 1'082 per cent, in the other.^ 
' See Report of Canadian CommiBdoDem, 1904. 



THE KJELLIN AND BOCHLING-RODENHAUSER 109 

The temperature o! the ateel when tapped is about 1,700° C. 
Using electric power at 40s. per e.h.p. year, the coat of producing 
steel by the Ejellin furnace and process was estimated at £7 per 
ton of 2,000 lbs., and the cost of erecting a 600-h.p. furnace was 
stated to be £830. 

Crushed magnesite or dolomite is used tor the lining of the 
annular ring, which acts as the melting pot for the furnace, and 
a little lime is also employed as a protecting slag. Considerable 



Fig. 51.— The 1,500-kg. Kjelliu Furnace at Gyeinge in operation. 

care is necessary when drying out the magnesite or dolomite 
lining before the furnace is employed for melting metal, and 
from sixty to seventy hours are requisite for this preliminary 
work. A lining lasts from four to eight weeks, according to the 
tonnage put through the furnace and the heat employed. The 
cost under American conditions of work is estimated at $1.00 
per ton of finished steel, and under European conditions would 
be proportionately reduced. 

Tests made with a 125-kw. furnace of the original Kjellin type 



110 ELECTEO-THERMAL METHODS 

have shown that under the most favourable conditions of work, 
1 metric ton of ordinary tool steel can be made with an 
expenditure of 650 kw. hours ; while the highest grade steel 
requires from 750 to 800 kw. hours. The furnace efficiency 
in these cases is about 70 per cent, to 75 per cent. 

According to Harden it has not been found practicable to 
make more than six melts in twenty-four hours with this older 
form of Kjellin furnace when a high grade tool steel is required, for 
the reason that the steel must be left quiescent in the furnace at 
a high temperature for a considerable period, in order to allow 
the occluded gases time to escape. Steel can in fact be melted in 
the Kjellin furnace with an expenditure of 590 kw. hours per 
metric ton, but the maintenance of the heat during the " killing " 
period adds from 60 to 200 kw. hours to this total. 

Fig. 51 shows a 1,500 kg. Kjellin furnace in operation at 
Gysinge. 

The disadvantages of the older form of Kjellin furnaces are 
stated by Harden to be as follows : — 

(1) Only small quantities of metal can be dealt with at each 
melting. If the section of the bath be made wider, the resist- 
ance is lowered and the power-factor diminished; while if the 
ring be made of larger diameter and of smaller section, the dis- 
tance from the primary will be increased and the power-factor 
again diminished. 

(2) The comparatively low temperature makes it impossible to 
keep the slag sufficiently fluid to obtain rapid removal of the 
sulphur and phosphorus. 

For these reasons the use of the original Kjellin type of 
induction furnace is confined to the melting down and mixing of 
scrap and fine steel that does not require purification, and its 
application as a refining furnace is no longer attempted. For 
the latter purpose, the furnace has been modified greatly by 
Rodenhauser and Schonawa, and what is generally known as the 
Rochling-Rodenhauser combined resistance and induction furnace 
has been evolved. The first furnace of this type was started 



THE KJELLIN AND EOCHLING-BODENHAUSEB 111 



at the BochlingiBche Iron and Steel works, at Yolklingeu, in 
Germany, in 1907. The tollovin'g description of the furnace 
was given by Harden in a paper read before the Faraday Society 
in Jane, 1908 :— 

The combiaed furnace coitsiate of a transformer furnace with two 
or three ring-sliaped baths, adjacent and communicating with one 
another and with a square or rectangular hearth placed in the centre 
between the rings. Doors are provided in front and behind, and the 
external appearance is very much like that of a Siemens open- 
hearth furnace. On closer 
examination, however, the 
principal feature is seen to 
he a heavy secondary wind- 
ing of copper cables, placed 
around and co-axial with the 
primary, one on each leg of 
the core and surrounded by 
the rings forming the charge. 
These copper secondaries, 
consisting of a few turns 
only, are connected to con- 
ductive plates built into the 
furnace wall, two in front 
and two at the back for a 
single-phase furnace. These 
plates consist of corrugated 
cast steel plates having a 
compound of nmgnesite, 
dolomite, and tar applied 
firmly over the corrugations. The plates do not conduct well when 
cold, but as soon as the furnace is charged with molten raw material 
they act as " conductors of the second class," and readily allow the 
current to pass. Thus about one-half of the power is transmitted to 
the charge by induction in the rings, and the other half of the power 
through the side plates. As the copper secondary is placed very close 
to the primary, the " leakfield " is very much smaller than with the 
original Kjellin furnace. A far more important gain, however, is to be 
found in the metallurgical possibihties obtained with the new design. 

For carrying out any refining process with steel, a sufficiently 
liquid slag and ways and means of handling the same, are 




Fig. 52.— The Bochling-KodenhauBei- 
Single-phase Furnace (elevation and 
plan). 



112 ELECTBO-THERMAL METHODS 

required. This is obtained in arc furnaces by the arc, which 
pla;8 between the carbon electrodes and the slag "blanket." 
In the combined furnace of Eocbling-Rodenhaueer, the elag is 
raised to and maintained at the required temperature in the 
resistance portion of the furnace, the conducting side plates of 
which are quite neutral. One portion of the power is converted 
into heat and utilised in the rings, thus heating the charge of 
metal ; the remainder passes through the side plates to the 



extent that experience has proved necessary, and is utilised 
chiefly in heating the slag. The ring-shaped portion of the 
furnace is covered with bricks at a height below the level of the 
charge in the centre bath. Thus no slag can enter into the 
rings ; and as it is the slag which is injurious to the lining, 
the rings need hardly any repair during a long run. The 
rectangular bath in the middle, on the other hand, is easily acces- 
sible, and can easily be repaired. The lining is simply calcined 
magnesite or dolomite mixed with tar and tamped in hot. It has 
been said] that the use of these steel side plates would be 



THE KJELLIN AND ROCHLING-RODENHAUSER 113 

equivalent to a return to the old system of carbon electrodes with 
all their disadvantages, but it is evident from what has been 
stated above that this is not the case. Practically no consump- 
tion whatever of these plates takes place, and they can hardly be 
called ** electrodes " in the strict sense of the word. Figs. 52 to 
56 explain clearly the construction of the combined resistance 
and induction types of furnace. The method of working is 
described by Harden as follows : — 

After the lining is tamped in, the tar is burnt out either by 
heating a cast-steel ring, or by pouring a small quantity of 
molten pig-iron into the hearth. This method leaves behind a 
sintered mass, forming a solid brick of basic lining. The pig- 
iron used for this preliminary heat is teemed out and is utilised 
for treatment in the Bessemer converter ; and a fresh charge is 
given, tapped direct from the converter. It has been found in 
practice more economical to burn out the carbon and the silicon 
in the converter, before refining from phosphorus and sulphur 
in the combined type of electric furnace. The largest furnace at 
Volklingen takes a charge of four tons. Calcined lime is added 
to form a suitable slag ; this slag sometimes contains about 6 per 
cent, of magnesia. In case of need a small quantity of fluorspar 
is also added to act as a flux, but this is not always necessary. 
Plate scale from the rolling-mills is employed for decarbonising. 
When in a sufficiently fluid condition the slag takes up the 
phosphorus very readily, after which it is made more viscous by 
adding cold lime, and is then drawn off through the slag-door by 
a slight tilting of the furnaces. It is essential for a successful 
dephosphorisation that the charge should be what is called 
" hot brittle " (i.e.), have an excess of oxygen, in order to prevent 
the phosphorus striking back into the charge again. After remov- 
ing the slag containing nearly all the phosphorus, ferrosilicon 
or carbon is added, in order to form SiOa or CO2, thus depriving 
the charge of the oxygen. It has been found that the addition 
of ferrosilicon is advantageous since it shortens the time of the 
deoxidation. If power be cheap carbon may be employed ; but 

E.T.M. I 



114 



ELECTRO-THERMAL METHODS 



in the case of a costly power supply, it is better to use the 
ferrosilioon. As soon as the dephosphorising is completed and 
the first slag has been entirely removed, a Ireah slag of lime only 
is formed. This when the temperature is raised acts as de- 
eulphuriser by formation of iron sulphide. The] oxygen is also 
driven out in this operation, partly hj combustion of the 
ferrosilicon or carbon whereby the temperature is increased, and 
partly by adding a small quantity of other active reagents. 




Calcium carbide is generally formed during this stage of the 
refining process. 

Finally, the maximum power is applied, in order to drive' out 
the last traces of oxygen, and as soon as no more gas hubbies 
are seen to leave the charge, a test piece is taken out and forged. 
If too soft for the purpose some coke powder is thrown in until 
the fight proportions are arrived at. As a rule the operation is 
finished in from one-and-a-quarter to two hours, but if necessary 
the steel can be kept in the furnace for ten hours or more 
withoat disadvantage. It is thus possible to treat a material 



THE KJELLIN AND ROCHLING-RODENHAUSER 115 

which contftina up to O'l per cent, phosphorus and O'l per cent- 
sniphur, so that a product will be obtained contaiaing only 



0'006 per cent, phosphorus, and 0"02 per cent, sulphur, with 
from 0'6 to 0"! per cent, manganese and 0*01 silicon. 

It has been urged against the Kjellin and Boehling-Rodeohauaer 
types of induction furnace, that the steel produced is of irregular 

i2 



116 ELECTRO- THERMAL METHODS 

quality and compOBition, owing to the differenceB ot temperature 
that exist in different parts of the bath. Engelhardt, in an article 



published in the German technical paper named below,^ has 
eiamined into this charge, and has brought forward evidence to 
disprove it. The most interesting portion of this refutation is 

1 Sta/d «. Eiicn, No. 16, 1910. 



THE KJELLIN AND EOCHLING-EODENHAUSEE 117 

that contained in Section IV. of his article, in which practical 
notes upon their experience with the Kjellin and Eochling- 
Eodenhauser furnaces are given by several German licensees 
who have installed this type of furnace in their works. Amongst 
the firms who stated they had not found any inequalities in the 
composition of the steel, made in the combined type of induction 
furnaces, are Messrs. Fr. Krupp & Co., of Essen, the Bergische 
Stahlindustrie, of Eemscheid, and the Poldihiitte, of Kladno. 

As regards the power of consumption and costs of operating 
the ** combined " type of induction furnace, Harden in the paper 
referred to above states that when molten metal from the 
Bessemer converter is charged into the furnace, only from 125 
to 150 kw. hours are required per ton of finished steel, and 
that 130 kw. hours may be taken as a good average. Vom 
Baur, in a letter published in the issue of MetalL and Chem. 
Engineering for January, 1912, gives 200 to 250 kw. hours 
per metric ton for the work of a 10- ton furnace refining basic 
Bessemer steel, which contained before treatment in the electric 
furnace '08 per cent, phosphorus and "09 per cent, sulphur, and 
only one-tenth of these amounts after the refining operation. 
According to the same authority, the Eochling-Eodenhauser type 
of induction furnace will melt cold scrap, with an expenditure 
of 580 kw. hours per ton, and the following details were 
given by him in a paper read on May 23rd, 1911, before the 
American Foundrymen's Association, for the operating costs of 
a 2-ton furnace at Volklingen : — 

Table XXIII. Per long ton. 

Dols. Dole. 

700 kw. hours for melting at '6 cent, per 

kw. hour 4*20 

200 kw. hours for refining at *6 cent, per 
kw. hour . . . . . . .1*20 

5-40 



Fluxes, etc., roll scale 22 lbs., lime 77 lbs., fluorspar 

11 lbs., sand 20 lbs., ferro-nianganese 8*8 lbs. . '44 

Loss of fluxes owing to a quarter of all metal remain- 
ing in the hearth 16 



118 ELECTRO-THEEMAL METHODS 

Table XKUL,— continued. Per long ton. 

Dols. 

Labour, two to three men ..... 1*50 

Tools, repairs, and lining -67 

Depreciation 10 per cent., interest 5 per cent, on 

11,300 dols.— 300 days, 6 tons per day of 12 

hours— 1,695 dols. ^ 1,800 = . . . . -94 

Auxiliary apparatus (cooling air for transformer) . '04 



Total 9-15 

Adding this, we get — 

Raw materials 12*60 

Conversion costs . . . . . . 9*15 



Cost of one ton electric steel ready to pour . 21*75 

To this cost must be added a slight licence fee per ton, 
depending on the output. 

Time of heat about 4 to 4|^ hours. 

Working with hot metal — drawn from the blast furnace, 

mixer, cupola or other type of furnace — the consumption of 

power is, of course, considerably reduced, and the following 

figures are given by Vom Baur for the cost of refining hot metal 

taken from the mixer at Dommeldingen, under American 

conditions, of work. 

Table XXIV. Dols. Dols. 

Raw material ...... 1200 

Oxidation loss 3 per cent. . . . . *36 

12*36 

Current 280 kw. hours at '6 cent, per kw^. hour 1*68 

Fluxes, etc '60 

Labour . ........ *50 

Tools, repairs, and lining '64 

Depreciation 10 per cent., interest 5 per cent, on 

17,000 dols.— 300 days at 40 tons per day of 

24 hours— 2,550 dols. -r- 12,000 tons= . . *22 

Auxiliary apparatus ...... '06 



Total .... 

Cost of preliminary refining, about 

Total cost of one ton of electric steel ready to pour 

Time of each heat about 2^ hours. 



16-06 
3*00 

1906 



THE KJELLIN AND ECJCHLING-EODENHAUSEE 119 



The estimated cost of refining hot metal melted in the cupola, 
and consisting mainly of steel scrap, having about 2 per cent, 
carbon in the resultant mixture, is as follows : 



Table XXV. 






Dols. 


Dols. 




Raw material 14*00 






Total oxidation loss 8 per cent. . . .1*12 


15*12 




Conversion cost similar to the above 


4-90 




Cost of preliminary melt in the cupola, about . 


3-00 


mj 



Cost of one ton of electric steel ready to pour . 

Time of each heat about 3| hours. 



2302 



A more detailed estimate of cost for English conditions of work 
was given by Kjellin in a paper contributed to the Niagara Falls 
meeting of the American Electro-chemical Society held in May, 
1909. The production cost of steel for rails in a 7-ton three- 
phase Bochling-Bodenhauser furnace was given in this paper as 
74s. 8rf. per ton, and for soft boiler plate 79«. Sd. per ton ; the 
following summary showing the various items which made up 

these totals : — 

Table XXVI. 



Material charged . 
Power — 

Heating up 

Refining . 
Wages — 

On furnace 

On linings 
Materials for lining 
Tools .... 
Repairs 

Depreciation and interest 
Licences 



For 


For 


Bails. 


Boiler Plata. 


s. d. 


s. d. 


66 3 


. 60 3 


1 


, 2 


3 


. 5 9i 


8 


. 1 i 


OJ 


. 1 


3i 


. 7 


4| 


. ii 


9| 


■ 91 


8 


. 1 5 


2 6 


. 2 6 



Total costs, per ton of steel . 74 8 



79 3i 



120 ELECTEO-THEEMAL METHODS 

As a final estimate of power consumption and costs, that given 
by Thieme in an article contributed to the September 8th, 1910, 
issue of the Elektrotechnische Zeitschrift may be quoted, this 
article containing a very full and detailed description of the 
electric steel works of Le Gallais Metz & Co., at Dommeldingen, 
Luxemburg. The estimate is for steel produced in a three-phase 
Eochling-Eodenhauser furnace of 5 tons capacity, using fully 
blown molten raw material containing '08 per cent, phosphorus, 
•08 per cent, sulphur and '12 per cent, carbon, and with power 
costing 4*5 pf. per kw. hour. It is assumed that this furnace 
can produce 10,000 tons of finished steel in 250 working days of 
eight heats per day. 



Table XXVII. 



Depreciation on 10,000 marks . 
Power consumption 280 kw. hours 
Materials for slags, etc. 
Linings and repairs . . . . 

Wages 

Air blast for cooling transformer coils 



Marks per ton 

of finished 

steel. 

1-00 

12-60 

2-25 

2-50 

•75 

•21 



Total 19-31 

This total is one for running costs only, no estimate for the 
cost of raw materials or for interest and royalty charges having 
been included in it. 

Passing on now to a consideration of the chemical and physical 
tests of the steel produced in the Kjellin and Eochling-Eoden- 
hauser induction furnaces. Harden states that the finished steel 
is distinguished by its great strength and homogeneity, and that 
rails have been made with much higher bending and breaking 
coefficients than the rails made from Bessemer or Thormas 
steel. These electric steel rails are also said to have sold at a 
price from 25s. to 45s. per ton higher in Germany than ordinary 
steel rails, owing to their greater durability. The following tests 



THE KJELLIN AND ROCHLING-RODENHAUSER 121 



are given as typical of the steel produced in the Bochling- 
Bodenhauser furnaces : — 

Table XXVIH. 



No. 


c 


Mn 


Si 


s 


P 


Tensile 
strength. 
Tons per 

sq. in. 


Elongation. 
Per cent. 


Con- 
traction. 
Per cent. 


1 


0*55 


0-9 


0-30 


0-03 


005 


53-2 


18-5 


31-4 


2 


OoO 


0-9 


0-26 


0-026 


006 


520 


190 


26-7 


3 


0-55 


0-85 


0-29 


006 


004 


62-5 


170 


30-8 



Low Carbon Electric Stebl. 



0-094 



0-30 



0086 



0025 



Trace. 



23-22 



36-0 



71-6 



Vom Baur, in the paper read before the American Foundry- 
men's Association, already referred to, gave tables containing the 
chemical and physical tests of various classes of steel made in 
the combined Bochling-Bodenhauser furnace. From these tables 
the figures given in Tables XXIX. and XXX. are taken. 

Table XXIX. — Analysis of Steel made in Rochling-Rodenhauser 

Furnace. 



^T^ *.# 




c 


Si 


Mn 


s 


P 


Cr 


Ni 


No. of 
charge. 


Quality. 


per 


Per 


Per 


Per 


Per 


Per 


Per 




cent. 


cent. 


cent. 


cent. 


cent. 


cent. 


cent. 


1,458 


Very mild for welding . 


004 


Traces. 


0-24 


0-006 


0007 






1,406 


Mild for case hardening . 


0-18 


0-16 


0-62 


0009 


0009 






1,692 


For machines and wagons 


0-45 


0-20 


0-62 


0011 


0008 






1,738 


For machines and wagons 


0-61 


0-20 


0-71 


0006 


0010 






1,242 


Nickel steel for case 


















hardening . 


0-21 


014 


0-61 


0-012 


0-010 




3-77 


1,683 


Nickel steel . 


0-33 


0-20 


0-36 


0-009 


0010 




3 06 


1,609 


Chrome nickel steel for 


















case hardening . 


0-12 


0-20 


0-29 


0-011 


0010 


0-91 


3-93 


1,292 


Chrome nickel steel 


0-34 


0-17 


0-32 


0-006 


0-011 


1-23 


3-61 


1,302 


Special spring steel. 


0-67 


1-53 


0-44 


0-004 


0-011 







In conclusion, a few details may be given of the most notable 
installation of electric induction furnaces of the Ejellin and 



122 



ELECTRO-THERMAL METHODS 



Bochling-Rodenhauser type, namely that to be found at the 
steel works of Le Gallais Metz & Co., at Dommeldingen, 
Luxemburg. This electric installation of electric furnaces started 
work in September, 1909, and so far as the writer is aware, 
is still in successful operation. The firm possesses three blast 
furnaces working on the iron ores of the locality which contain 
40 to 45 per cent. iron. Each furnace produces 4 X 25 ton 

Table XXX. — Tests of Steel made in Roohling-Rodenhauser Furnacje. 





Elastic 


Tensile 


Elongation. 
Per cent. 


Redaction of 


Heat No. 


limit. 
Lbs. per sq. in. 


strength. 
Lbs. per sq. in. 


area. 
Per cent. 


1458 


31,300 


43,400 


35-4 


70-0 


1406 


44,100 


69,400 


26-5 


54-6 


1692 


61,150 


96,580 


20-2 


420 


1738 


70,250 


114,360 


15-0 


35-6 


1242 


54,600 


76,100 


23-5 


640 


1583 


65,130 


86,760 


21-9 


500 


1509 


64,560 


83,900 


22-3 


64-0 


1292 


104,680 


123,740 


13-3 


48-0 


1302 . 


, 68,260 


112,640 


15-2 


43-0 



charges of pig-iron per day, and the waste gases are employed 
for running the electrical portion of the plant by means of a 
compound gas engine, built by the Maschinen-Fabrik Augsburg- 
Niirnburg. This engine is direct coupled to an alternating- 
current generator of 1,800 kilowatts capacity built by Felten and 
Guilleaume, with an output of 210 to 360 amperes at 5,000 volts. 

A 25^ kilowatt 10-pole exciting dynamo is also driven by the 
same gas engine, while a Zoelly steam turbine coupled to a 
1,000 kilowatt Siemens-Schuckert alternator provides the re- 
mainder of the power required. 

The steel refining portion of the plant comprised originally 
two transformers, to reduce the E.M.F. and periodicity of the 
current as generated to that required for operating the furnaces, 
and three Bochling-Eodenhauser furnaces, two of 4 tons and 
one of 1^ tons capacity. Figs. 55 and 56 show one of the 



THE KJELLIN AND ROCHLING-BODENHAUSER 123 



Fio. 57. — Details of TraiiBformer Construction for a Kjellin FuroEuie. 

single-phase furnaces at this works ready for operating an 
also discharging. A very complete account of the whole plant, 
illustrated by numerous photographs, is given by H. Thieme, in 



ELEOTEO.THEEMAL METHODS 



^lo. 58. — Details of Transformor Construction for Eoohling-Eodenhauser 
Three-phase Furnace. 

the issue of the Elektro-technische Zeitschrift for September Sth 
and 15th, 1910. 



THE KJELLIN AND BOOHLING-EODENHAUSER 126 



Fig. 59. — Detoilfi of Transformer Construction for Eoohling-Eodenhauser 
Three -phaee Furnace. 

Fig. 57 shows a 736-kilowatt transformer coil, designed for 
the original form o( EjelUn furnace. The transformer core was 



126 



ELECTRO-THEEMAL METHODS 



built up of laminated sheet iron, and the coil consisted of 
hundreds of turns of insulated wire. This transformer was 
designed to take current at 4,500 to 4,900 volts pressure. The 



Sifatem 


Weight 


Charge 


Volt 


Amp 


K.W. 


Hours 
12 3 4 5 




1600 
kg. 


Cold 
















4 




■sawr 




noo 




















f ijy 




90W 




no 


^ 




- A.'Wr. 












■"" 




"~» 


3800 




«0 




"^-, , 




V 








-'' 






. X 


MM 




iM 






Ka/( ■ 


















^^ 




11^ 



















; 


2 


3 


4000 
kg. 


Hot 


3400 


930 


«90 








3 


4 
















■55WJ 


90(} 


*00 




Vol 




















_2fiS- 


'**■■ ■ 1 ■ ■ ■ r 






3600 


«6 


SflO 




















■5BWr 


uo 


840 




















2400 


«0 


?^ 

















J 


2 


1 
1 

1 

1 


8000 
kg. 


Cold 




















5100 


980 


































IWO 


9{^ 


©00 


, 












JWff 


i?9 


'W 












TTzVunr 


"WOO 


*9~ 


"W 


y^"""" 








==55fr: 



































































1 


2 


3 


4 


5 


8000 
kg. 


Hot 
















4 














































*8W 


IffO 


TJOO" 






.^J 




«W«r 


-TOO 


"WW 




















)/r 












, /{I 


W-. 







































1 


2 


3 



Fig. 60. — Graphic Eepresentation of Power BequirementB of Kjellin and 

Eochling-Eodenhauser Furnaces. 

coil was 5 ft. in diameter and 2^ ft. in depth ; the whole frame 
and coil weighed 35 tons. 

Fig. 58 shows details of the transformer construction for a 
Bochling-Eodenhauser induction furnace designed for three-phase 



THE KJELLIN AND ROCHLING-EODENHAUSEE 127 

current. This transformer is provided with three cores and with 
three coils, attached above and below to a horseshoe-shaped 
form of yoke, to give the requisite rigidity. The method of 
building up the cores and winding the coils is similar to that 
employed for the single-phase furnace. 

Fig. 59 shows this transformer enclosed and provided with 
the requisite pipes for air cooling. One of the special 
advantages expected from this type of construction was, that 
the three electro-magnetic fields produced in the furnace would 
lead to better mixing of the molten metal. This effect was 
certainly produced, but the greatly increased wear and tear upon 
the lining of the furnace was found to more than balance this 
gain, and the author is informed that owing to the heavy cost 
of repairs this type of furnace construction, for use with 
three-phase current, has not been further developed. 

Fig. 60, giving the current and voltage curves for several 
runs with Kjellin and Eochling-Eodenhauser furnaces, charged 
with both solid and liquid raw material, shows that these 
furnaces operate with remarkable steadiness, especially when 
charged with molten metal, and that the variations in the power 
consumed are so slight that they can be worked directly from an 
ordinary electricity supply without the installation of special 
generators. This is a feature of these induction furnaces which 
should render them specially suitable for installation in large 
ironworks, where the present-day tendency is for the whole 
power supply of the works to be generated as three-phase 
current from large gas engines, operated by the hitherto wasted 
gases from the coke ovens and blast furnaces. The special 
feature of these ** curves " is their resemblance to straight lines 
rather than to curves. No power engineer who has had the 
charge of a generating plant supplying current for electro- 
metallurgical purposes can fail to appreciate the significance and 
advantages of this " straight line " form of power curve. 



CHAPTER Vm 

THE EELLBB ELECTRIC BTBEL BEFININO FURNACE 

C. A. Eelleb, head of the well-known French firm of Keller, 
Leleux et Cie, manufacturers of calcium carbide and ferro- 
alloys, has designed two distinct types of electric refining 
furnace for steel production — the 
first and earlier type with two or 
more electrodes connected in series ; 
the second and later type, with a 
compound conducting hearth (or 
sole) to the furnace. The earlier 
furnace resembles the Heroult refin- 
ing furnace, the latter one that of 
Girod ; and the resemblance in each 
case is sufficiently close to render 
the question of patent priority and 
validity somewhat interesting. 

Fig. 61 shows a diagrammatic 
Fio. ei.-Eeller'a Pumace, elevation of the earlier Keller smelt- 
earljr type, diagrammatic ing and refining fumace From 
this the furnace is seen to consist 
of a fixed sheet-iron chamber lined with basic refractory 
material, and heated by two massive carbon electrodes 
suspended vertically above the metal in the fumaca When 
working the fumace these electrodes were allowed to touch the 
surface of the molten slag, but not to dip beneath the same, and 
this appears to have been the chief distinction between the Keller 
and Heroult processes of electric steel refining. 

A furnace of this type of 800-kgs. capacity was erected at 
Eerrousse in 1902, and was worked there experimentally for 



KELLER ELECTRIC STEEL REFINING FURNACE 129 

some months. It was transferred later to the works of Keller, 
Leleux et Cie, at Livet, and a trial run was made here in 1904 
with the furnace by the Canadian Commissioners. Unfor- 
tunately lack of time to complete the refining operation caused 
the failure of the test, and no figures were published for the 
Keller furnace in their report. The experience gained, however, 
at Kerrousse and Livet in the application of this type of furnace 
to steel refining led to the design and erection, in 1905, of an 
8,000-kg. furnace at the steel works of Jacob Holtzer & Co., at 




Fig. 62.— Keller's 8,000-kg. Furnace at Unieux (section). 

Unieux, France. This installation is claimed by Keller to have 
been the first example of the introduction of an electric furnace 
into a modern steel works. Even if this claim be incorrect, 
Keller appears to have been the first electro-metallurgist to 
recognise that the electric steel-refining furnace could be most 
usefully and economically employed for the final stages of steel 
making, rather than for the whole process. For the Keller electric 
refining furnace had been charged with molten metal during the 
experimental trial runs at Livet, instead of with cold scrap, and 
at Unieux, this system of working has been further developed. 
Fig. 62 is a sectional elevation of the Unieux furnace, and 

E.T.M. K 



ISO ELECTBO-THEEMAL METHODS 

Fig. 63 is a plan of the same. The furnace was of the fonr-pole 
type, and weighed with its equipment 50 tons. The melting 
chamber was mounted aa shown on rollers, and was provided 
with hydraulic machinery, by means of which it could be tipped. 
Pour rotating supports were provided for the double electrodes. 
These when turned inwards came under a central overhead 




Fio. 63.— Keller's 8,000-kg. Furnace at TJnieux (plan). 



block, where they made contact with the electric supply mains. 
The four supports were completely independent of the furnace 
proper, and it was quite possible to remove the cover of the latter 
for repairs, without any loss of time in removing the electrodes 
from their supports. 

By this system four zones of heat were produced within the 
furnace, and the current flowing through each pair of electrodes 



KELLEE ELECTRIC STEEL REFINING FURNACE 131 

could be independently controlled and regulated. The move- 
ments of the electrodes in a vertical direction either 
upwards or downwards were also subject to independent control, 
one, two or four electrodes being moved as required. The 
arrangement adopted for the distribution of the current to the 
eight electrodes was on the star plan, and was designed to reduce 
the induction losses to a minimum, and to permit the removal 
and renewal of the carbon electrodes without stopping the 
furnace. The furnace hearth was lined with magnesia, and was 
mounted so that it could be tipped either forwards or backwards • 
The gas generated during the refining process accumulated 
within the furnace and created a plus pressure, a condition 
which was favourable to the exclusion of air and the prevention 
of oxidisation of the finished steel. 

Operating Costs. 

The following results have been obtained with this furnace 
at Unieux with molten metal charged into the electric furnace 
from a Martin open-hearth furnace, by means of a cradle 
carrier : — 

TABLE XXXL 

Molten metal charged, 7,500 kgs. 

Composition of ditto, Carbon, '15 per cent. ; Sulphur, '06 per 

cent. Phosphorus, '007 per cent. 
Mean power consumption, 750 kw. 
Carbon contents desired, '45 to '50 per cent. 
Time of refining operation, 2 hrs. 45 mins. 
Composition of finished steel, Carbon, '443 per cent. ; Sulphur, 

'009 per cent. ; Phosphorus, '008 per cent. 
Power consumed per metric ton, 275 kw. hours. 
Electrode consumption, 10 kgs. costing at 40 frs. per 100 kgs., 

4 frs. per ton of steel. 

The power-factor with a current of 12,000 amperes was 
stated to be very high, namely, '97, and Keller estimated that a 
furnace of this type, using three-phase current, could purify 
250 tons of steel per day, at an inclusive cost of 12s. 6d. to 

k2 



182 



ELECTRO-THERMAL METHODS 



15«. 6d. per ton, when using electric power costing '15^. per 
kw. hour. 

The installation of Unieux appears to have been the only one 
of the earlier type of Keller furnace, outside the inventor's own 
works at Livet, and the later industrial developments have 
occurred with the type provided with a conducting hearth or 
sole. The description of this furnace is based upon that given 
by Keller, in a paper read before the Faraday Society in 1909.^ 

The whole of the 

1 ■ I bottom of this type 

of furnace is made up 
of a block, which is 
partly metal and 
partly refractory 
material. It is a con- 
ductor, and is also 
practically infusible 
at all working tem- 
peratures of the fur- 
nace. The liquid 
metal does not rest 
on a masonry bottom, 
but on a combination, 
which is to the ar- 
rangement of masonry 
fitted with metallic poles, as reinforced concrete is to the 
ordinary substance. 

Iron bars 25 to 30 mm. in diameter are placed vertically at 
regular intervals of about 25 to 30 mm. apart. These bars are 
fixed solidly in the bottom of the furnace, thus forming a bundle 
which fills the whole of that part of the furnace containing the 
molten steel. A clay of some agglomerated material, magnesia 
for preference, is closely rammed when hot between each group 
of four rods. These latter form in fact a mould, which permits 

^ Transactiam of the Faraday Society^ Vol. V., pp. 118—121. 




<j{^\m^^^m^^^^^^^^^^ 



Fig. 64. — ^Keller^s Furnace with Conducting 
Hearth (sectional elevation). 



KELLER ELECTRIC STEEL REFINING FURNACE 183 

the mixture to be rammed in with some degree of force. A very 

compact mass is thua obtained, composed of iron bars and 

refractory material in regular arrangement. It is a conductor 

when cold bo far as the metal portion of it is concerned, while 

at high temperatures the refractory material also conducts. This 

compound hearth or sole is contained in a metal case which is 

used as a covering, and can be cooled by a current of water. 

The lower conducting base and all the iron bars are connected, 

by any suitable means, to one of the poles of the source of 

energy. The construction 

described above allows the 

furnace to be started very 

easily. The small distance 

between the bars and the 

conductivity of the clay 

cause them to be in parallel 

throughout their length 

when the furnace is start- 

iog-up, and the current is 

distributed equally over the 

whole surface of the hearth. 

The concentration of the 

current that is produced at '^^^- SS.-KeUer-a Furnace with Con- 

" ducting Hearth (pUd). 

points in a furnace fitted 

with isolated metallic poles is not created by this arrangement, 
for the current on leaving the electrode crosses the whole section 
of the molten metal, and leaves in the same regular way over 
the whole surface of the hearth. It is in fact claimed by Keller 
that the electrical resistance of such a conducting hearth is 
practically negligible, for the extent of the furnace-bottom allows 
a large number of bars to be employed, while the conductivity of 
the clay must also be taken into account. As a result, the loss 
due to resistance is very small. The use of metal conductors of 
small section gives rise also to a more rational distribution of 
an alternating current than with other methods of construction. 



134 ELECTRO-THERMAL METHODS 

The conducting hearth forma the bottom of the melting 
chamber of the furnace, which is constructed otherwise on the 
tiBual Hnes, with a. double lining of some refractory material to 
the walls. The shape of the melting chamber is conical, and in 
order to give the necessary solid foundation a basin of magnesia 
clay is placed at the bottom of the furnace. This clay is easily 
repaired when necessary after the melt. The furnace casing is 



Fio. 66. — Keller's Furnace with Conduotiog Hearth (section showiDg 
method of supportinj; the electrodes). 

cooled up to the level of the upper part of the hearth, in 
order to protect the junction of the melting chamber with the 
hearth. 

The furnace is closed by an arch, through which the 
electrode passes. The regulation of this electrode is effected 
by hand or by an automatic regulator; the latter arrangement 
is the simpler. In order to obviate the stoppage necessary 
when changing the electrode, the latter is fixed at the end of 
a rotating support which carries another electrode ready for use. 



KELLER ELECTRIC STEEL REPINING FURNACE 135 

A new electrode can be iaeerteii in two or three minutes by 
merely rotating the supporting arm. The cooling ot the furnace 
sole is carried out on the water-jacket principle, the means 
employed being similar to thoae used in the construction of 
other metallurgical furnaces. The sheathing only of the 
furnace is cooled by meana of cast-iron plates, in which are 
embedded the iron tubes through 
which the cooling water circulates. 
It is claimed that no danger of 
explosion would follow the break- 
ing of one ot these tubes. Fur- 
naces of this type can be employed 
with three-phase current, the 
electrical connections being made 
on the star plan, and the armoured 
clay hearth of the furnace being 
made the neutral or middle point 
of the system. As regards repairs, 
the hearth of a 1,500-kg. furnace 
showed no signs of wear when 
examined after many months of 
service. 

Furnaces of this second type 
(with a conducting hearth) have 
been installed at six works in 
France, Germany and Italy, but 
no details- concerning their actual ^^'^' '^ Vf^Skr'e^^iSnS ^"^' 



costs of operation or i 
yet available for publication. A conducting hearth furnace is 
being used at Livet for melting a ferro-manganese alloy before 
it is added to liquid steel. Figs. 64 — 66 are illustrations of 
the Keller conducting hearth type of furnace. 

The details of the method used by Keller for connecting the 
heavy carbon electrodes to their supports is shown clearly in 
Fig. 67, and deserves some comment. The supports are 



136 ELECTRO-THERMAL METHODS 

conslructed of ratlier wide and flexible thin bars of copper, 
^ mm. only in tbickness, connected at one end with the fixed 
current leads and at the other end with the carbon electrode 
blocks. The head of each carbon is provided with a cavity, into 



Fig, 68.— General View of Keller's Conducting Hearth Furnace in 

operation. 

which the expanded end of the flat and flexible current lead ia 
fastened, by aid of molten bronze or of some other suitable metal. 
One obtains in this way a joint which is both electrically and 
mechanically perfect, while allowing some vertical movement to 
occur. As already pointed out, the renewal of the electrodes 



KELLER ELECTRIC STEEL REFINING FURNACE 187 

when consumed up to the head of the carbons is simplified b; 
the revolving arms of the electrode sapport. 

Fig. 68 shows a general view of the Keller conducting hearth 



Fig. 69.— Keller's 

type of furnace, and Fig. 69 the same furnace being charged 
with molten metal. A list of the installations of the Keller 
furnaces in Europe is given in the Appendix of this book. 



CHAPTEE IX 

THE FBIGK, OBONWALL, HIOBTH, AND STOBIE FUBNAGES 

The previous chapters of this book have dealt with the five 
electric farnaces for steel refining that have been longest before 
the public and have received the widest trial. It is now the 
author's duty to devote some space to descriptions of those 
furnaces which have not attained so great a success, but are none 
the less deserving of study and attention. These furnaces have 
been designed and erected with the data derived from the earlier 
experiments to guide and warn their patentees ; and it is quite 
possible that some of them may prove of higher efficiency, and 
be found capable of more economical working, than any that 
have preceded them. 

The information relating to the construction of these furnaces 
and to their working costs is, of course, not so voluminous as 
that of the better-known types, and in some cases there is little 
data available for arriving at any just estimate of their practical 
value for steel-refining purposes. The present Chapter and 
Chapter X. contain, however, detailed descriptions of the more 
important of these furnaces and processes ; and information as to 
the running costs is added, where the figures are available for 
publication. 

The Frick Electric Eefining Fomace. 

The Frick Eefining Furnace is of the induction type, and 
differs only in comparatively unimportant details from the Kjellin 
and Colby furnaces. According to Lyman,^ the furnace consists : 

(1) of a ring-shaped crucible of uniform cross-section, holding the 
molten metal and forming the secondary of the transformer ; 

(2) of a magnetic core built of laminated iron, forming a closed 
magnetic circuit around the coils ; and (3) of two primary coils 

1 Transactions of tfie American Mectro-c/ufmical Society^ Vol. XIX., p. 197. 



FKICK, GR5NWALL, HIORTH AND STOBIE 139 



of iBBulated copper ribbon, moanted one above and one below 
the crucible, on the magnetic core. These coils may be wound 
for any desired voltage up to 6,600 volts. 

Fig. 70 is a diagrammatic section of the Frick furnace. A 
1,000-h.p. furnace of this type was built for Messrs. Fried. 
Krapp, at Essen in 1910, and has been in regular use since 
January of that year. This furnace has a capacity of 20 tons 




Fio. 70. — Diagrammatic section of the Flick Furnace, 
steel per day, when charged with cold scrap, and requires about 
six and a-half hoars to melt and refine each 6^ tons charge. 

The following figures for the operation of this furnace during 
a run of forty-two days are given in the Journal named below * : — 
Table XXXII. 
Durationof melting period, June 2 — July 14, 1910 42 daj's. 

Number of charges 134 

Average time per charge 6^ hours. 

Metal charged 883 tons. 

Steel produced 850 „ 

Loss per cent, on metal charged .... 3'73 per cent. 
Kw. hours per ton of steel produced . . 6fi3 

' The Iron Trade Beview, Nov. 17, l!)l(l. 



140 ELECTRO-THEEMAL METHODS 

The power required was approximately, therefore, one kw, 
hour for each three pounds of steel refined, or 663 kw. hours per 
ton. To obtain a reasonably high power factor, a special low- 
frequency current of 360 amperes and 5,000 volts (at 5 to 15 
cycles) was used, and an engine-driven generator designed to 
furnish this low-frequency, single-phase current was also 
employed. The electrical power supplied was controlled by 
regulating the generator voltage. The efficiency was said to be 
about 65 per cent. The power consumed in melting the material 
(cold iron and slag) and raising this charge to 1,500° C. in a 
10-ton furnace, was approximately 600 kw. hours per ton, or 
0*3 kw. hour per pound. The power consumed for refining the 
steel after melting was from 1,800 to 2,000 kw. hours for a 
10-ton charge, or approximately 0*1 kw. hour per pound. 

As regards the two Frick furnaces which have been erected 
and operated in Sheffield, England, only limited information is 
available. A 250-h.p. furnace, with a working capacity of 
4,000 lbs. per charge, was erected at the works of Messrs. John 
Brown & Co. for experimental purposes and is stated to have 
given satisfaction, while Messrs. William Jessop & Sons have a 
larger Frick furnace of 6,600 lbs. capacity, and utilising 600 h.p. 
No working figures for the power consumption of these furnaces 
have been published. 

The Ordnwall Refining Furnace. 

This furnace is of the " arc " type, and has been designed by 
the three Swedish engineers, Messrs. Gronwall, Linblad, and 
Stalhane, who have been responsible for the design and working 
of the successful Electric Iron Smelting Furnaces at Ludvika and 
TroUhatten, in Sweden (see Chapter I.). The Gronwall refining 
furnace is of the two electrode ** arc " type, and in principle and 
appearance differs only slightly from the Girod and Heroult 
furnaces. The bottom of the furnace is, however, provided with 
a conducting lining, and the current passes through the molten 
metal and away by this path when two-phase current is employed, 



PEICK, GR(5NWALL, HIOETH and STOBIE 141 



the hearth being made the neutral return of the system. The 
advantages of this plan are, — that two-phase current is cheaper 
to generate and more 
easy to control than 
single-phase, while it 
also produces more cir- 
culation in the bath of 
molten metal. 

Figs. 71 and 72 show 
sectional elevations of 
the Gronwall furnace at 
right angles to one 
another. The furnace 
is built up on the curved 
cast-iron plates which 
form its shell, a lining 
of magnesite bricks being employed between the ordinary basic 
lining and the shell of the furnace. The two electrodes are sus- 
pended, as shown in Fig. 71, and hang with their free ends just 




Fig. 71.— Section of Gronwall Furnace. 




Fig. 72. — Section of Gronwall Furnace. 

above the molten slag or metal. In the larger furnaces, at the 
point where they pass through the furnace crown, they are water- 
cooled. The furnace can be tilted by aid of the mechanism 



142 



ELECTBO-THERMAL METHODS 



shown in Fig. 72. The carbon block forming the lower terminal 
of the furnace is fixed in a casting bolted to the furnace bottom. 
The top of this bottom electrode does not project above the 
magnesite brickwork, and it does not therefore weaken the basic 
lining of the furnace. The roof consists of a channel-iron 
framework, closed in with silica brickwork, and can be removed 
from the furnace and repaired when necessary, a new roof being 
always kept in reserve ready for aee. 

The spoeial feature of the electrode holders is, that the 




FiQ. 73. — Diagram of Electric Circuits in Hiorth Furnace. 

electrical contact is made low down, just above the furnace 
roof ; this reduces the energy losses due to the internal resistance 
of the electrode. The holder consists of strong iron castings and 
T irons. Owing to the use of two-phase current, and to the fact 
that each phase is connected to one of the top electrodes, the 
arcs are formed independently of each other ; and even if one arc 
be broken, the other remains. In other arc furnaces, with the 
arcs in series, when one arc is interrupted the other is also 
extinguished, and this leads to disturbance in the supply system. 
The details of the process of steel refining in the Gronwall 
furnace are the same as in the Qirod, Heroult, and Keller 



FEICE, GRONWALL, HIOKTH AND STOBIE 14S 

furnaces, the high temperature obtainable leading to good 
purification, and the good circulation to uniform quality of the 
steel produced. No figures, however, are available shoving the 
power consumption per ton of finished steel, or the total costs of 
the refining process. These should be rather lower than the 
corresponding figures for the other furnaces of the " arc " type, 
owing to the economies resulting (1) from the use of two-phase 
current, (2) from steadiness in working, and (8) from more even 
distribution of heat throughout the charge. The Qronwall 
furnace is installed at 
the Electric Iron and 
Steel Works of the 
Aktiebolaget Elektro- 
m eta 11 at Ludvika, 
Sweden. 

The Hiortk Beflning 
Furnace. 

This furnace is the 
invention of Albert 
Hiorth, of Christiania, 
Norway, and is an im- 

provedformoftheinduc ^"^i.-^^SS^ ^/S^'o^""" 
tion type of furnace. A 

5-ton furnace has been operated at the Factory of the 
Jossingfjord Manufacturing Co., at Jossingfjord, Sogndal, in 
Dalene, Norway, since the spring of 1910, and the experience 
gained with this 5-ton furnace haa been utilised in designing 
a larger furnace of 80-ton capacity. The 30-ton furnace, so far 
as the writer can learn, is not yet working. The following 
description of the smaller furnace is drawn chiefly from a paper 
by J. W. Eiehards, read before the Chicago meeting of the 
American Electro-chemical Society in 1910.^ 

The Jossingfjord Works are provided with a 500 kw. generator, 

1 Tram., 1910, Vol. XVUI., p. 191. 



144 ELECTRO-THERMAL METHODS 

driven by a Pelton wbeel ; the power here costs only 17s. 8d. 
per h.p. year. The 5-ton furnace is a double-channelled 
induction furnace, with a primary consisting of four coile con- 
nected in Beries. Fig. 73 shows the electrical principles, E 
being the steel bath, with its two channels DD, A the magnetic 
circuit, BB the upper eoils, co-extensive with the heating 
channels, and CO the lower coils. The coils BB are suspended 
from pulleys with flexible connections, and when running, are 
close against the covers of the channels DD, but can be raised 
about 60 cm., when the 
covers are to be removed. 
The coils BB are non-in- 
sulated bare copper bars, 
coiled spirally. The coils 
CO are hollow, water- 
cooled copper conductors, 
and in the actual furnace 
are embedded in the 
m^^esite lining about 
40 cm. beneath the chan- 
nels DD. The voltage 
Fia. 76.— Section of Hiorth's o-tonFurnac* employed On the primary 
.lJo«mrtord, lipped for di,ch»ging. .^ ^^ |^^ j^^j ^ ^^ 

ticular precautions for insulation are needed, and no one can 
be seriously hurt by it. The space between the magnet A 
and the furnace wall is a clear 30 cm., which allows of the 
magnets (weighing several tons) being bolted firmly to the 
floor, while the furnace can be tilted for pouring. The 
central space (E) is 30 cm. wide in the middle, 60 cm. wide at 
the sides, and nearly 2 metres long from front to back. 
Space enough is therefore provided to re-melt ingots or other 
scrap. 

The figures in Table XXXHI. (see next page) of a heat 
with this furnace are given by Richards in the paper referred to 
above. 



FEICK, GRONWALL, HIORTH AND STOBIE 145 

Table XXXIII. 

P.M. 

12.30. In furnace, 2,775 kgs. of previous charge of steel containing 
1*00 per cent, carbon. 

Charged 1,000 kgs. pig-iron, and 500 kgs. Walloon iron. 
Current started. 

12.30. Current 1,800 A, 273 V, = 380 kws. cos. 9 0-77. 
1.30. Current 1,840 A, 273 V, = 395 kws. cos, 9 0*80. 
2.0. Current 2,050 A, 265 V, = 380 kws. cos. 9 070. 
2.30. Charge melted. Average current 380 kws. for 2 hrs. 10 mins . 
= 550 kw. hrs. per ton of metal melted. 

2.30. Charged 350 kgs. pig-iron, and 1,150 kgs. Walloon iron. 

3.30. CuiTent 2,275 A, 270 V, = 400 kws. cos. 9 0*65. 

4.30. Charge melted. Average current 400 kws. for 2 hrs. = 

530 kw. hrs. per ton of metal melted. 

5.30. Current 2,370 A, 265 V, = 395 kws. cos. 9 0*63. 

6.00. Current 2,425 A, 278 V, = 400 kws. cos. 9 0-59. 

6.15. Current 2,300 A, 280 V, = 365 kws. cos. 9 0-57. 

Assuming 300 calories necessary to melt 1 kg. of steel, the 
thermal efficiency of this melting operation is 55 per cent, and 
the furnace radiation loss is represented by 180 kw., at this 
temperature. It was stated that it took about 170 kw. to keep 
the charge melted, when the furnace was kept up to heat over- 
night. 

The metal was now at a casting temperature, and the total 
power used was 895 kw. for six hours, equivalent to 790 kw. hours 
per ton of steel. Other test runs with this 5 -ton Hiorth furnace 
have shown that one ton of steel could be produced in it, with a 
power consumption of only 700 kw. hours. 

During the above heat, 35 kgs. of 30 per cent, ferro-silicon 
and 8"7 kgs. of 80 per cent, ferro-manganese were added to the 
bath ; while when casting '15 kg. pure aluminium was added in 
the ladle. The steel was poured into 20 cm. square ingots and 
cast well. 

The materials used were the purest Swedish Dannemora 
pig-iron from the middle bed of the Dannemora deposit, and 
Dannemora Walloon iron, costing, respectively £6 5s. Orf. (108 

E.T.M. L 



146 



ELECTEO-THERMAL METHODS 



kroner) and iJ15 12«. 6d. (270 kroner) per metric ton. These 
are the identical materials used in Sheffield to produce the best 
quality of crucible steel. Yellowish-white blast-furnace slag, 
vitreous and glassy, from the Dannemora furnaces, was being 
used as a flux, mixed with fluorspar when greater fusibility was 
desired. The contents of the furnace being 5 tons, 3 tons were 
poured at a time and 2 tons left in to start the next charge, which 
then consisted of 3 tons of raw materials. The analyses of these 
raw materials and of some of the steels produced from them, are 
given below : — 

Table XXXIV. 



/ 


Carbon. 


Silicon. 


Man- 
ganese. 


Sulphur 


Phos- 
phorus. 


Daanemora, White pig . 
„ Walloon iron 


3-80 
0107 


0-310 
0-013 


1-727 
0-068 


0-025 
0010 


0-020 
0-009 


Steel .... 


1-42 
1-20 
102 
0-76 
0-67 


0-130 
0-107 
0112 
0-108 
0-108 


0-322 
0-269 
0-301 
0-253 
0-288 


0-010 
0-009 
0-008 
0-009 
0-006 


0-019 
0-019 
0-021 
0021 
0021 



The steel produced is being shipped to Sheffield for use in the 
steel works, for the manufacture of knives, razors, chisels, etc., 
and enters into successful competition with the best crucible steel 
selling at £60 per ton. The capacity of this 5-ton furnace is 12 
tons in 24 hours, 3 tons of finished metal being poured every six 
hours. Under regular conditions of work 700 kw, hours are 
used per ton of cold metal charged. 

Figs. 74 and 75 are sectional elevations of the Hiorth 5-ton 
furnace installed at Jossingf jord. Figs. 76 and 77 are photographs 
of the same furnace, showing the external appearance. 

The larger 30-ton Hiorth furnace, to which reference has 
been made, is not yet erected, but a full report of the data upon 
which its design has been based will be found in a paper contri- 



FRICK, GEONWALL, HIORTH AND STOBIE 147 

buted by Hiortb to the Toronto (1911) meeting of the American 
Eiecfcro-chemicftI Society (Tram., Vol. XX, p. 298). From tbie 
paper tbe following details are extracted : — 

With regard to the new design the first condition was that 
the space for the charge must be large enough to hold 80 tona. 



Fio. '6. — External details of Hiorth 5-ton Furnace at JoaBingfjotd. 

but the actual dimensions and shape of the bath most be such 
as to give the best possible power-faetor. 

In order to increase the capacity of the furnace, it was neces- 
sary to increase Ihe sectional area of the bath more than the 
length, as otherwise the diameter of the bath, and consequently 
the dimensions of the furnace, would become too large. The 
resistance of the bath would thus be considerably decreased, and 
at the same time the inductance would be increased, owing to 
the larger diameter, which increased the area of the space between 
the primary and tbe secondary windings. 



148 ELECTRO-THERMAL METHODS 

The power-factor would thus in any case be reduced with the 
increased capacity, and the designer calculated that a 30-ton 
furnace built on the same lines as the smaller one, for single- 
phase current, with a two-leg magnet and a current supply with 
twenty-five alternations, would show a power-factor equal only to 
0'25, and that the power-factor even with fifteen alternations per 
second would still be only 03 8. 

It was therefore decided that the SO-ton furnace should be 



Fig. 77.— Top view of Hiorth 5-ton Funiace at Jossingfjord. 

built on the three-phase principle, instead of the single-phase. 
In this case the weight of the charge per ring was only 10 tons, 
instead of 15 tons as with a single-phase furnace, and the reduction 
of the power-factor was not nearly so great. Hiorth states that : — 
" 111 order to facilitate the tilting ol the furaace, the three rings were 
disposed in one row. This arrangement is not strictly symmetrical, 
and it is to be expected that the load on the middle phase will be 
somewhat different from tUe load on the two outer ones, on account of 
the difference both in the inductance and in the resistance. With a 
special electric power supply this is, however, not a very serious draw- 



FEICK, GEONWALL, HIOETH AND STOBIE 149 



back, particularly as the difference between the phases in all probability, 
will not be very great." 

The dimensions finally chosen for the new furnace are shown 
diagraramatically in Fig. 78, and a comparison of the more 
important data for the 5-ton and 30-ton furnaces is given in the 
following table : — 

Table XXXV. 

Comparative Data of 5-ton and 30-ton Hiorth Furnaces. 





Old Furnace. 


New Furnace. 


Total capacity 




5 tons 


30 tons 


Capacity per leg . 




2*5 tons 


10 tons 


Diameter of bath . 




21m. 


3 m. 


Width of bath . 




20 cm. 


30 cm. 


Depth of bath 




27 cm. 


45 cm. 


Total surface of masonry 




55 sq. m. 


110 sq. m. 


Total length of platform 




S^m. 


13 m. 


Total width of platform 




5i m. 


6-5 m. 


Sectional area of core per le^ 


r 

5 


1,800 sq. cm. 


1,200 sq. cm. 


Weight of core . 


> . 


15 tons 


23 tons 


Number of primary turns p 


er leg 


15 


13 


Sectional area of primary wir 


idings 


1,000 sq. cm. 


4,000 sq. cm. 


Weight of copper per leg 




0-875 tons 


ca. 4*5 tons 


Total weight of copper 




1-75 tons 


ca. 13*5 tons 


Energy used 




250 kw. 


700 kw. 


Copper losses 




12-3 kw. 


40 kw. 


Iron losses .... 




18 kw. 


18 kw. 


Power factor 




0-65 


0-50 


Voltage .... 




250 


230 


Periodicity (half alternation 


s per 






second .... 




12| 


8 


Amperes per phase 




1,400 


3,540 


Kind of current . 




1 phase 


3 phase 



The Stohie Heating and Refining Furnaces are the invention 
of Mr. Victor Stobie of Sheffield, and are of the combined arc 
and resistance type. They differ, however, in some important 
details, from the Girod type of furnace construction. As a result 
of long experience in the Sheffield tool-steel manufacture, the 
designer of these furnaces has come to the conclusion that for 



150 ELECTRO-THERMAL METHODS 

small furnaces arc-heating alone is not economical, and that some 
portion of the current ought to be employed concurrently for 
~ resistsnce heating, by aid of a, conducting lining to the furnace. 

In the first experiments, a two-phase furnace vas used which 
was provided with a single electrode embedded in the hearth, con- 
nected to the neutral point of the supply system, and with two 
electrodes above the bath connected to the two phases of the 
supply. It was found, however, that by this arrangement, the 
passage of the whole of the return current (which is equal to 70 per 
cent, of the sum of the currents in the two phases) had too great 



Fig. 78. — Diagram of Hiorth's 30-ton Furnace. 

a heating effect on the lining of the furnace, and it was impossible 
to obtain satisfactory results. 

To overcome the difficulty caused by this overheating of the 
lining, the two phases were kept separate, and two electrodes were 
introduced into the hearth, each having an area three times as 
large as usual. The top electrodes immediately above these were 
connected to the same phase of the supply system, the result 
being that each return current was obliged to travel by a separate 
conductor and to cross in direction, through the molten metal in 
the bath. The advantages of this arrangement according to 
Stobie are : — 

(1) The current density through the lining of the furnace is 
only a portion of what it was in the older type of two-phase 



FRICK, GRONWALL, HIORTH AND STOBIE 151 

furnace, and the bottom heating is sufficient for the purpose, 
without disintegrating the furnace lining. 

(2) The current travels through a longer path in the bath thus 
helping the resistance heating. 

(3) The crossing of the currents in the bath produces a mixing 



Fig. 79. — Diagrammatic section of Stobie's Two-phase Furnace. 

motion which is unobtainable in other designs, except by bard 
rabbling. 

Fig. 79 shows a plan and sectional elevation of the Stobie 
two-phase furnace. 

The three-phase furnace relies only on arc heating, as Stobie 
admits that in large furnaces there is no necessity to reinforce 



l52 ELECTRO-THEBMAI; METHODS 

this by resistance heating. His three-phase current furnace is 
provided with four carbon electrodes, three of these being con- 
nected to the three terminals of a star -connected three-phase 
current supply, and the fourth is connected to the neutral point 
of the supply. According to the designer of the furnace, the 
latter is only required because a three-phase current when used 
for electric furnace work can never be perfectly balanced, and a 



FiQ. 80. — Diagrammatic aection of Stobie'e Three-phase Furnace. 
certain portion of the current is always travelling back, via the 
neutral point within the furnace, at which heat is being developed- 
Pig. 80 shows a plan and sectional elevation of the three-phase 
furnace. 

No figures are available showing the power consumption or 
running costs of these furnaces, but the furnaces have been tried 
experimentally in Sheffield, and the Stobie Steel Co. has been 
formed to finance and equip a works in Newcastle with furnaces 
of this type. Two 15-ton furnaces on the three-phase system 



FEICK, GRONWALL, HIOETH AND STOBIE 153 

and two or more 5-ton two-phase furnaces are now in coarse of 
erection, and therefore within a few months one may be able to 
obtain reliable working figures for the operation of the Stobie 
type of furnace construction. 

A supplementary patent of Stobie'a relates to the use of oil 

or coal-gas for " bum- 

ing-in " the hearth 
bottom of the furnace, 
and also for the pre- 
liminary heating and 
melting of the charge. 
The advantages 
claimed for this are : — 

(1) The bottom 
lining of electric fur- 
naces by this method 
can be made as solid as 
in the best open-hearth 
practice; whereas 
formerly the lining 
had to be rammed 
and was never 
thoroughly burnt 
beyond an inch or 
two from the surface. 

(2) The preheating of the charge gives the advantage of a 
reduced power consumption, which has previously only been 
obtained by the use of molten steel melted in another furnace, 
such as an open-hearth or Bessemer installation. 

Fig. 81 is a diagrammatic section of this oil- or gas-heated 
furnace. 



Fig. 81.— Diagrammatic section of Stobie's 
Combined Electric and Gas or Oil-heated 
Furnace. 



CHAPTER X 

THE ANDERSON, CHAFLET, COLBY, ORBENE, HXRDEN, HERINO, NAU, 
NATHUaiUB, QUBSNAU, REID AND SODERBERQ FURNACES 

The group of furnaces described in this Chapter are less 
developed indaatrially than the furnaces dealt with in the pre- 
vious Chapters of this book ; 
but for the reasons given in 
the introductory paragraph 
of Chapter IX. they are not 
on that account the less inter- 
esting or deserving of atten- 
tion. 

The Anderson FutJtace is 
the design of T. Scott Ander- 
son, of Sheffield. The furnace 
is shown in sectional elevation 
in Fig. 82. In its general 
appearance and design it 
resembles closely the refining 
Fig. 82.-Ai.dM^n Furnace (sectional furnace of Heroult. The fur- 
nace is provided with two 
electrodes capable of vertical movement ; these are water 
jacketed and may be worked either in parallel or series, 
according to the nature of the work required from the furnace. 
The special feature of the Anderson furnace is, however, the pro- 
vision of electro-magnets beneath the base of the furnace, by 
means of which the arc formed between the two electrodes can 
be drawn downwards and controlled. It is further claimed for 
the Anderson furnace that " the concentration of the incandes- 
cent gases around the electrode is utilised to the best advantage," 



MISCELLANEOUS FURNACES 155 

and that the arrangement of the furnace " tends to efficiency in 
a very marked degree," 

No details of the practical installatione of this furnace or of 
its working costs are available, but according to the patentee, 
four furnaces, each of 5 tons capacity, have been installed and 
are now working upon the production of steel from pig-iron. 

The Chaplet Furnace is shown in sectional elevation in 
Fig. 83. The two electrodes are seen to be suspended in two 
different chambers or divisions of the interior of the furnace, 
which are connected by a 



lateral canal. The electric 
current flows from the posi- 
tive to the negative electrode 
by means of the metal con- 
tained in this canal, as shown 
by the arrow in Fig. 83. 

The metal in the larger 
chamber of the furnace is 
therefore melted and purified 
by combined arc and resist- 
ance heating, and the furnace 
resembles both in principle 
and in its method of operation 
the furnaces of Girod and 
Keller, with conductinf? hearths. A Chaplet furnace is reported 
by Keller to be in use at the works of the Acieries d'Allevard 
Isere, France, but no details concerning the size or efficiency of 
this furnace have been published. 

The Colby Fwnace is of the induction type, and was 
patented by E. A. Colby, in the U.S.A., in 1905. Fig. 84 
is a photograph of a small Colby furnace of 130 kw. capacity, 
installed for melting tool steel at the works of Messrs. Henry 
Disston & Sons, at Tacomy, near Philadelphia, in 1907. The 
general principles of the furnace design resemble those of the 
more widely-known Kjellin and Frick furnaces, but the following 



156 ELECTRO-THERMAL METHODS 

details of the Tacomy furnace may prove ot interest. The 
primary coil of the furnace consisted of twenty-eight turns of 
copper tube f in. inside and f in. outside diameter, through 
which water flowed for cooling purposes. The annular crucible, 
the molten metal in which formed the secondary circuit of the 



FiQ. 84. — A Colby Furnace in operation at Chicago, 

furnace, measured 24 ins. outside diameter and 15 ins. 
inside diameter, and was 8 ins. in depth. The trough held 
900 lbs. of steel when fully charged, and ingots of 90 lbs. were 
poured every hour. The fusion of the added metal required half 
and hour, and the refining and killing process another half an 
hour. The ingots poured were found to be very dense and 
homogeneous. The E.M.E. of the single-phase primary current 



MISCELLANEOUS FUENACES 157 

used was 240 volts, and the maximum current employed was 
540 amperes with a frequency of 60. The power used per 100 lbs. 
of metal poured was from 27*5 to 37*5 kw. hours, according to the 
purity of the charged raw materials and quality of steel desired. 
This is equivalent to from 605 kw. hours to 825 kw. hours per ton of 
2,200 lbs. The Colby Furnace Patents have been purchased by 
the American Electric Furnace Company, who also have secured 
the control of the Kjellin and Eochling-Kodenhausor Patents 
in the U.S.A., and it is stated by this Company that no 
Colby furnaces are now operating in that country. One 
may therefore assume that, both in efi&ciency and operating costs, 
the Kjellin and Rochling-Eodenhauser types of induction furnace 
are superior to the Colby furnace. Further details of the Colby 
furnace erected at Disston will be found in the issue of the 
journal named below.^ 

The Greene Process has been worked out by Albert E. Greene 
and makes use of any of the ordinary induction types of furnace 
for producing steel directly from pig-iron. The refining opera- 
tion is effected, however, by the application of a new principle, 
namely, the use of producer gas, which is blown into the molten 
metal that is present in the annular ring or crucible of the induc- 
tion furnace. The process is called the Electric Converter Process, 
and it is claimed for it that the losses incurred when refining 
pig-iron by the ordinary Bessemer or open-hearth processes are 
largely minimised. The following description of the process is 
taken from a paper contributed by Greene to the New York 
(1911) meeting of the American Electro-chemical Society:^ 

The process consists in providing a bath of molten low-phosphorus 
pig-iron containing the usual proportion of manganese, silicon, and 
carbon. The charge must contain suflBcient manganese and silicon, 
however, to more than meet the specification for the particular steel 
required. The temperature of the bath is raised to something over 
1,425° C, and is maintained at this temperature by electric 
heating, Avhile a gaseous mixture containing CO and CO2 is blown into 

1 Electrochemical and Metallurgical JEngi fleering for June, 1907. 

2 Transactions, Vol. XIX., p. 23;^. 



158 ELECTRO-THERMAL METHODS 

the metal, in much the same way that air ie blown ink) a Bessemer or 
Tropenas converter. The gaseous mixture may contain 12 fo 18 per 
cent, of CO, and 5 per cent, or more of COg. 

The rate of elimination of the carbon is a little slower than with the 
ordinary Bessemer process, for the same rate of blowing. A well- 
operated side-blown converter requires from twenty-five to thirty-five 
minutes to make a blow, ttsing about 1,500 cubic feet of air per minute 
per ton of metal. In the small induction furnace, using about 50cubic 
feet of gas per minute per 200 pounds (or about one-third the rate of 
blowing in the side-blown Bessemer converter just referred to), the 
carbon can be eliminated in something more than one and a half hours, 
the exact time depondiag 
on how much carbon there 
was in the raw pig-iron 
used. Thus, with only 
one-third as much gas 
blown per minute per unit 
weight of metal, the time 
is a little more than three 
times ns long, as tor a simi- 
larly blown vessel using air. 
By increasing the rate of 
blowing the time can be 
very greatly cut down. 
The rate of elimination 
depends largely on the 
nature of the contact of 
the gas with the metal ; and when the gas is blown through the metal, 
as in the case of this process, it is most rapid. 

It was found that the gas could be blown into the metal without any 
formation of slag on the surface and without any boiling. The most 
convincing evidence that oxidation does not take place in the process 
may be found in connection with the loss of manganese. In converting 
a 13'4 per cent, speigel-iron into manganese steel, the patentee states 
that he has dispensed with any additions of any kind, and that he baa 
produced a steel containing over 12'5 per cent, manganese without the 
use of a slag to prevent vaporisation. The carbon was reduced from over 
4 per cent, to 1'20 per cent. In later tests, using a lime slag, the 
vaporisation loss lias been further diminished. 

The procasB described above for oxidising carbon without 
oxidising iron is similarly applicable to the removal of phospbotus. 



MISCELLANEOUS FURNACES 159 

The patentee has found that he can eliminate the phosphorus from 
iron and hold it out by means of lime, and that he can effect this 
purification with practically no oxidation of iron and manganese. 
This elimination of the phosphorus has been carried out at 
temperatures below 1,350° C. without oxidising carbon; and 
it has also been effected at high temperatures (above 1,500° C. 
and up to 1,900° C.) after the carbon has been oxidised. 
In addition to these facts the patentee has found that 
the sulphur can be taken up and held in the same slag that 
holds the phosphorus ; this action being attributed to the absence 
of oxide of iron in the slag. 

A low-grade pig-iron has been converted into a high quality 
steel in one continuous operation in this way, taking out first the 
carbon without oxidation of the iron and manganese, and then, 
by continuing the blow of the gaseous mixture, with a lime slag 
on top of the metal, the phosphorus has been oxidised and elimi- 
nated. The phosphorus was found combined with the lime as 
calcium-phosphate, and practically all of the sulphur was found 
in the slag as calcium-sulphide. 

As regards the results obtained, Greene, in the paper referred 
to, gives the following analysis of the raw material and of the 
finished steel : — 

Table XXXVI. 

J ( Raw material. Phosphorus 0*76 per cent. Sulphur 0*113 per cent. 
( Finished steel. Phosphorus 0*026 per cent. Sulphur 0040 per cent. 

Raw material. Phosphorus 0*094 per cent. Sulphur 0040 per cent. 
Finished steel. Phosphorus 0*008 per cent. Sulphur 0017 per cent. 



"•{ 



Although Greene has stated that the process has been 
operated in the U.S.A., with the 2-ton induction furnace 
shown in Fig. 85, and that in larger furnaces of this type a power 
consumption of only 30 kw. hours per ton of steel would be required 
to work the same, the electric converter process does not 
appear to have developed industrially in the U.S.A. ; and 
the writer cannot refer to any existing plant where it is 



160 ELECTRO-THERMAL METHODS 

operated at the present moment. As a possible scientific develop- 
ment of the application of the electric induction furnace to steel 
manufacture, the Greene process is, however, of great interest and 
is worthy of close study. Greene has pointed out that the pro- 
vision of a suitable gas for working the process in large iron works 
would not be a difficult matter, as the substitution of a gas con- 
taining carbon monoxide and carbon-dioxide, for the air used in 
the ordinary Bessemer process, does not involve any change in 
present methods. A suitable gas for carrying out this process is 
available from cupolas or blast-furnaces, or may be made in a 
very simple gas-producer. Blast-furnace gas should be diluted 
by admixture with stack gas, since the percentage of carbon 
monoxide in blast-furnace gas is usually much higher than is 
required. The process itself (in so far as the elimination of 
carbon is concerned) is a gas-producer process, the evolved 
gas being richer in CO and lower in CO2 than that blown into 
the metal. This fact opens the possibility of using the gas 
over and over again, by burning a part of it in order to main- 
tain the desired composition. 

The Harden Furnace is of the combined arc and resistance 
type, and is designed to remove the defect attaching to the 
original type of Ejellin furnace, namely, that the temperature 
is too low and the slag surface too small, to permit the proper 
elimination of the phosphorus and sulphur from the charged 
metal. The new furnace has been termed by its designer the 
"Paragon" furnace, and is shown in section and plan in 
Figs. 86 and 87. The following description of it is given by 
J. Harden in a paper read before the Faraday Society in 
October, 1911.^ 

In this furnace the bath of metal is heated, not only from the 
surface of the slag by means of suitably arranged arcs, but also 
at the same time from the sides and beneath the bath, by means 
of side plates of second-class conductors, similar to those which 
have been used for some four or five years in the Eochling-Roden- 

1 Transactio'tis oftlie Faraday Society^ Vol. Vll., p. 183. 



MISCELLANEOUS FURNACES 161 

hsuser furnace. In tbiB manner the metallurgiat ia able to apply 
the maximum heat exactly where he wishes to have it, since both 
circuits can be regulated at will. Thua, during desulphuriaation 
and dephosphoriBstion, the slag ia heated to a temperature higher 
than that of the Bteel ; while during the period of degasifying, the 
greater portion of the power is conveyed to the bath through the 
bottom and sides. 

This design bringa in other important improvements. For 
example, it ia quite easy to atart the cold furnace by means of the 



FiQ. 86. — H&rden's Foragon Furnace in sectional elevation. 

area, thua diapensing with the necessity of filling in a liquid charge. 
Further, the electrode question in simple arc furnaces may in 
many cases become a serious one, as large electrodes lor furnaces 
of great capacities are exceedingly difficult to obtain, and are 
always very expensive. Owing to the nature of the " Paragon " 
furnace, where only a smaller portion of the power enters the 
furnace through the electrodes, this drawback is considerably 
reduced. If, for instance, the upper limit of a simple arc-furnace 
is 20 tons, on account of the difficulty in obtaining sufficiently 
large electrodes, it will be found that this capacity can be doubled 
with the " Farag;oq " type. 

E.T.M, H 



162 ELECTRO-THERMAL METHODS 

The electrodes for a SO-ton three-phase " Paragon " furnace 
would have a cross-section of 16 ins., or 256 sq. ins. 
only, and in a 50-ton furnace the electrodes would measure 
24 ina. by 24 ins., or 576 sq. ins. This would still only 
give a maximum current density of 24'5 to 26 amperes 
per square inch, which, as experience has proved, is well within 
reasonable limits, both from an electrical and manufacturiug 



Fia. 87. — Harden's Paragon Furnace (plan). 

point of view. These sizes of carbons correspond to simple arc- 
furnaces having capacities of only 12 to 14 tons and 18 to 22 
tons respectively. 

A farther advantage claimed for this design is the greater 
durability of the roof. It is well known that the roof is that 
portion of an ordinary furnace which is most rapidly destroyed 
by the action of the hot gases. In the "Paragon" furnace 
the destructive action is minimised, as only a small portion of 
the power is acting on the slag. 



MISCELLANEOUS FUENACES 163 

The " Paragon *' furnace has been patented by J. Harden and 
the Grondal Kjellin Company, Ltd., and an experimental 
furnace of the new type has been erected in Germany, at the 
Eochling Iron and Steel Works. No constructional details of 
this furnace have yet been published and no figures are available 
showing the working results; but it is expected that the 
" Paragon " furnace will prove more economical and more 
generally useful than any of the existing types, and that the 
special features of the design will permit larger furnaces, up to 
50 tons capacity, to be operated with success. 

The Hering '' Pinch Effect *' Furnace. 

The "pinch effect," upon which C. Hering's patent is based, 
was discovered by the patentee when working with an electric 
furnace, in which this effect was disadvantageous and not 
desired. 

The phenomenon is an electro-magnetic one, and is due to 
the physical contraction of the cross-section of any liquid 
conductor through which a current is passing, this contraction 
or " pinch effect " being sufiScient under certain conditions to 
rupture the conductor and break the current. Mr. Carl Hering, 
impressed with the practical possibilities of this phenomenon, 
has designed both an electric furnace and a valveless electro- 
magnetic pump upon the "pinch effect." Fig. 88 shows a 
diagrammatic cross-section of the Hering furnace, and Fig. 89 
shows a tilting furnace based on this principle. The following 
descriptions are taken from a paper read by E. K. Scott before 
the Faraday Society in October, 1911.^ 

Fig. 88 represents the cross -section of two liquid conductors (AA) 
surrounded by non-conducting material (BB). The current enters and 
leaves by water-cooled electrodes (CC) ; (D) being the transformer. 
Assuming for the moment that each liquid conductor is made up of 
a number of elemental conductors, it is clear that these wiU be 
attracted together in accordance with the law that *^ like currents 
attract." Circulation of the liquid is therefore set up as shown by 

1 Transactions, Vol. VII., p. 202. 

m2 



164 



ELECTRO-THERMAL METHODS 



the arrows, by the liquid moving from the circimiference to the 
centre. As one end of the hole is stopped up by the electrode, any 
pressure set up can only be relieved by the liquid moving upwards as 
in a fountain, and that is what actually happens. 

The furnace may be a tilting one (as shown in Fig. 89), or there may 
be a tapping-hole just above the top of the resistor tubes. In any 
case the resistor tubes must not be emptied, and sufficient metal must 
be left in the bottom of the furnace to connect them across. Fig. 89 
is drawn to scale, and it shows very clearly how small the two 
electrodes are, compared with the bulk of the furnaces. It also shows 
how the electrodes are inclined, this being done in order to reduce the 

back pressure on the surface of 

the electrode. 

Looking at the top of the 
charge, its appearance is some- 
what similar to that of water 
in rapid ebullition at two spots 
where heat is localised, but of 
course there is no noise and the 
bubbles are few. 

In some cases the agitation 
at the top of the metal charge 
is so great that the surface is 
inclined at 45 degrees. The 
suction down into the bottom 
of the resistor tubes is also 
considerable. 

It should be noted that the 
heating is entirely effected at 
the bottom of the charge, and the circulation from there is in a natural 
direction upwards. Heat is thus transferred to the whole of the charge 
by a vigorous stirring and not by mere suction. The electrodes are 
Usually made of the metal that is being melted. The sections of the 
electrodes and the current that passes are so proportioned, that the 
ends of the electrodes are raised to a temperature as nearly as 
possible equal to the temperature of the molten charge. 

Of the various materials used for electrodes, Hering's experience 
has proved that metal electrodes are distinctly cheaper and more 
economical in energy. Copper is the best and iron nearly as good ; 
gas-carbon is the worst, graphite being only slightly better than 
gas-carbon. 

As the hottest metal flows up the centre of the " resistor tubes " 




Fig. 88. — Hering Furnace in dia- 
grammatic sectional elevation. 



MISCELLANEOUS FUENACES 



166 



the lining does not have to withstand the greatest heat. Again, there 
is very little eroding action due to friction on the wall ; for the pinch 
effect tends to puU the metal away from the lining, and tends to form 
a vacuum there. This is just the opposite of the effect in other 
furnaces, where the circulation of the molten metal has given trouble 
by its digging into the lining. Alundum has been used for the 
lining, but as it had a tendency to crack magnesite powder is now 
employed. It is packed in whilst in plastic condition, and after being 
heated forms an extremely hard and smooth glossy surface. 

The rapid circulation obtained in the furnace allows chemical 
changes to take place rapidly ; this means great economy in time. The 
maximum temperature at any point does not need to be much above the 
normal. In other furnaces where circulation is sluggish, the tem- 
peratures in the charge vary a good deal. To allow for effective action 




Fio. 89. — Hering Furnace (sectional elevation and plan). 

of the slag it is important that the hottest metal should impinge 
directly upon it. This is exactly what takes place in the Hering 
furnace ; for when it leaves the centre of the tube, the heated metal is 
forced up against the blanket of slag. 

The furnace can be worked with either direct or alternating 
current ; three-phase current may also be employed. With 
alternating current, the power factpjr can be raised to practically 
unity ; the frequency need not be low, and may be chosen to 
suit the ordinary generating machinery. If the electrodes are 
made of the same metal or materiial as the charge, the furnace 
tends to be self-regulating as to temperature. The advantages 
claimed for the Hering pinch effect furnace are the following :— 

(a) It is simple and cheap, consisting merely of two holes (or 



166 ELECTRO^THERMAL METHODS 

three with three-phase current) in an ordinary furnace hearth, 
a simple electrode being fixed at the bottom of each hole. 

(b) The heat is generated by resistance in the charge itself, 
and the heating takes place at the bottom of the bath, just 
where it can be most eflfective. 

(c) The circulation of the hot charge is entirely automatic, 
and in a most effective direction, namely, from the bottom of the 
bath up to the underside of the blanket of slag. 

(d) The speed at which the mixing takes place is such that 
the charge is treated more rapidly than by other methods. 
Therefore, for a given size of furnace hearth, and given amount 
of electric energy, a larger amount of material can be dealt with 
per day. 

(e) The electrodes are of metal and cheap, being usually of 
the same material as the charge ; they do not consume away, as 
is the case with carbon and graphite electrodes. 

(f) In furnaces using carbon or graphite electrodes, the 
temperature of the furnace is quite frequently higher than is 
really necessary. With the Hering furnace, on the other hand, 
the temperature and circulation of metal may be exactly adjusted 
to the metallurgical requirements. 

(g) Heat from gaseous fuel can be applied to the top of the 
bath, without affecting any of the electrical gear. The current 
can be switched on all the time, or only for the refining part 
of the process. 

(h) All the electrical gear is out of the way on the underside, 
and if the furnace is required to tilt, a transformer can be 
attached to it, so that the flexible leads for the high-tension 
current can be of small section. 

In his Patent Specification, Hering claims that with slight 
modification, the pinch effect furnace might be applied to making 
steel direct from the ore. For this purpose a double furnace 
would be employed, and the carbon monoxide gas given off by 
the one furnace would be employed to preheat the ore. In one 
section of the furnace carbon would be dissolved in the iron— in 



MISCELLANEOUS FUENACES 167 

the other, iron oxide— and by the reaction of the two solutions 
the carbon would be eliminated. 

Since the above description of the furnace was published, it 
has been stated by the inventor that if (when melting steel) a 
carbon rod be held in front of one of the squirting tubes it 
dissolves like a stick of candy in hot water ; on the other hand, 
iron ore placed on this carbonised iron gave off large volumes of 
gas, showing that the ore was being reduced by the carbon in the 
iron, just as in the open-hearth process. With this combination, 
Bering therefore proposes to use the furnace for the reduction of 
iron ores. 

The material to be employed for the construction of the 
resistor-tubes is of considerable importance in its bearing 
upon the working costs of the furnace. Magnesite and alundum 
have so far been employed, and good results have been obtained 
with both, but the use of other materials is now being considered, 
and electrically calcined magnesite is to be used for the next 
furnace constructed. The lining of the resistor-tubes is 
tamped in around a mould when in a plastic condition ; it thus 
forms part of the general refractory lining of the furnace. 

No data are yet available showing the actual working results 
obtained with this new type of refining furnace, and in view of 
the criticisms that have been expressed with regard to the wear 
and tear on the resistor-tubes, some little time must elapse 
before any trustworthy opinion as to the commercial and 
industrial possibilities of the furnace can be formed. 

As regards the capacity of the furnaces of this type with which 
the trials have been conducted, only small experimental furnaces 
have yet been used. The Ajax Metal Company of Philadelphia, 
however, have purchased the patent rights, and intend to develop 
the industrial applications of the Hering furnace, both for steel- 
refining and for melting brass and other non-ferrous metals. 
This company hopes to have four or five of these furnaces at 
work, on a commercial basis, in 1913. They have demonstrated 
in their own preliminary trials that sulphur can be more 



168 ELECTRO-THERMAL METHODS 

easily eliminated in this type of furnace than in the arc furnace. 
A recent test made in the presence of American steel experts is 
stated to have shown a reduction in sulphur contents of the steel 
from "066 per cent, to *012 per cent, in 50 minutes, using a slag 
composed of lime and fluorspar. This rapid elimination of the 
sulphur is stated to be due to the active circulation of the metal 
under the slag blanket. 

The Nau Furnace and Process have been designed for the 
preliminary refining of phosphoretic pig-iron, too high in its 
silicon contents for treatment directly in the open-hearth furnace. 
The process is protected by U.S. A. Patent No. 786048 of 
1905, and depends upon running liquid pig-iron through a column 
of heated iron ore, and in allowing a bath of molten metal to 
accumulate at the bottom of the ore column. The intimate 
contact between the molten pig-iron and the ore maintained at a 
high temperature leads to a chemical reaction between the 
silicon and the iron-oxide of the ore ; and the temperature 
attained is found to remain sufficiently high to produce both a 
fluid slag and a molten pig that can be run easily from the 
melting furnace. The silicon and portion of the phosphorus and 
manganese are eliminated by this process, and are found in the 
slag. The patentee of the process has also designed a special 
form of electric furnace which allows easy immersion of the ore 
in the metal that is to be refined. This furnace, according to the 
description given by the designer in the journal named below,^ 
is capped by a water-cooled roof and is surmounted by an ore- 
shaft, with a lateral inlet for the liquid pig-iron that is to be 
refined. Vertical electrodes penetrating the roof are placed 
around the shaft. The bottom is made of carbon paste, and the 
electric current passing between the electrodes and the carbon 
bottom traverses the liquid metal and slag. 

The furnace is so arranged, and the operations are so con- 
ducted, that the ore required as refining medium is kept immersed 
to any desired depth in the molten pig-iron. As soon as the ore 

^ Metall. and Chem. Engineering^ March, 1911. 



MISCELLANEOUS PURNACES 



in the bath is coDsamed and has to l>e replaced by new ore, the 
latter can be immersed without any trouble in the liquid bath. 

The patentee has calculated that the removal of the silicon, 
phoBphorns and manganese will demand 44,724 calories per ton 
of metal treated, and that in order to supply this loss of heat, 
and to maintain the metal and slag at a temperature of 1,200° 
to 1,400° C, 2,100 e.h.p. hours will be required. Under more 
favourable conditions, the chemical reactions, however, might 
supply sufBcient heat 
to keep the process 
working without any 
external heat supply; 
and at times, no 
doubt, the process 
could be worked as a 
Belf-Bupporting one. 

No data relating 
to this process, 
beyond those given 
by Nau in the article 
referred to above, 
are available, and it 
would appear, there- 
fore, that both the 
process and furnace are still in the experimental stage of their 
development. 

The Nathvaius Furnace is a design which seeks to combine 
the advantages, and to escape the disadvantages, of the Heroult 
and Girod types of furnace. 

The furnace is of the combined are and resistance type, and is 
shown in section in Fig. 90, and in operation in Fig. 91. The 
furnace is seen to be provided with three carbon vertical 
electrodes, arranged symmetrically above, and with three 
extra steel electrodes, arranged below (or in the bottom of) the 
crucible. These six electrodes are connected to the inner and 



170 ELECTRO-THERMAL METHODS 

outer termmals of a three-phase generator ; the molten metal in 
the crucible itself forming the neutral point of the system. As 
both the upper and lower electrodes are of mutually alternating 
polarity, the metal in the bath is subject to a great variety of 
heating cnrrents, and the thermal efficiency of the furnace is 



Fio. 91. — General external view of Kathusiua Furnace 
in operation. 

stated to be high. Further advantages claimed for this furnace 
are : — (1) Excellent mixing of the metal and the production of a 
uniform melt, results due to the rotary fields set up by the vertical 
currents that traverse the molten bath. (2) Rapid heating, due to 
the presence of three arcs, and of three fields of heat activity. (3) 
The convenience and economy of a three-phase current supply. 



MISCELLANEOUS FUKNACES 171 

(4) Easy regulation by means of a booster transformer, or by a 
special generator with an adjustable neutral conductor. (5) The 
heat effect can be concentrated where it is most desired ; namely, 
in the slag during the earlier stage of the refining process, and 
in the molten bath during the later stages, when the slag has 
finished its work and the " rest " or quiescent period of the 
refining process has been entered upon. 

The furnace is of the tilting type. Fig. 91 shows the external 
appearance of the furnace, the electrodes being suspended from 
ordinary cables by means of pulleys, and operated by means of 
high-speed motors. Some further details of the Nathusius furnace 
will be found in the issue of the journal^ named below. No 
figures for the power consumption and running costs of this 
furnace have yet been published. 

The Queneau Furnace is similar to that of Bering, both in 
principle and design, the "pinch effect" of powerful electric 
currents being made use of to produce a series of regular 
pulsations in a bath of molten metal, heated by ordinary 
resistance. One or more steel electrodes are fixed in the bottom 
of the furnace. The upper ends of these are molten, and are in 
direct contact with the molten furnace charge. These columns of 
molten steel which form the electrodes are enclosed in cavities 
lined with magnesite bricks set in tar, and the continual make 
and break of the electric current caused by the "pinch effect" 
creates a series of regular pulsations throughout the molten 
charge. Further particulars of this furnace will be found in the 
papers referred to below.^ No data based on the actual operation 
of this furnace have been published. 

The Reid Refining Furnace, as shown in Fig. 92, is a simple 
arc furnace, with carbon electrodes. It is protected by U.S.A. 
Patent No. 947849, granted to J. H. Reid in February, 1910, and 
it forms only one portion of the " Reid system of electric smelting 
and refining." No efficiency or costs data relating to this furnace 

* Electrical Review^ London, April 5, 1912. 

3 Metallurgical and Cfiemical EngiTieering, March and June, 1910. 



172 ELECTRO-THERMAL METHODS 

are available for publication, and it does not appear to have 
been applied to steel refining on a commercial scale of operation. 
T}te Sodei'berg Furnace is of the combined arc and resistance 
type, and is similar in 
principle and design to 
that of Nathaeius (see 
p. 169). Richarda, in 
the TransacUona of the 
American Electro-chemi- 
cal Society^ has given 
details of a furnace of 
this type which is being 
erected at the works of 
the Joasingfjord Manu- 
fac taring Company in 
Norway. The furnace 
is circular, and will hold 
2*5 tons of metal. The 
three electrodes passing 
through the roof are 
connected to a three- 
phase generator by a 
"star" connection. Six 
small electrodes, each 
Pro. 92.— Experimental typo of Eeid J >n- >° diameter, are 

Furnace. embedded in the hearth, 

and serve as connection to the bath. This latter acts as the 
neutral point of the system. Little or no current passes through 
these embedded electrodes ; consequently the arcs from the 
upper electrodes pass in one direction only, namely from the 
electrodes to the bath, and are not in series with one another. 

' Vol. XX., p. 413. 



CHAPTER XI 

COMPARATIVE POWER CONSUMPTION AND RUNNING COSTS 

The preceding Chapters have contained a very large numher 
of figures relating to the power consumption and running costs 
of the various furnaces and processes described. It is the 
author's purpose in this, the final Chapter of the book, to reduce 
this mass of data to a form in which the results may be more 
easily compared. It is necessary to note, however, that when all 
the values of power, weight, and value have been reduced to one 
common form of expression, there will still remain the differences 
due, (1) to the greater or less impurity of the pig-iron and steel 
used for the refining process ; and (2) to the extent to which the 
electric refining operation is varied in the production of a pure 
product ; and (8) to the varying rates of wages and costs of 
materials in the different countries. For these reasons, compara- 
tive power and costs data require most careful investigation and 
study before they can be used as guides to the relative eflSciency of 
competing electric steel-refining furnaces and processes. In 
those cases where no chemical analyses of the raw materials and 
finished steel are given, the data are, for comparative purposes, 
practically worthless. Even when full details of the chemical and 
physical tests have been presented, only a practical steel-maker 
and metallurgist can judge of the comparative efiSciencies of the 
refining processes. 

The author proposes, therefore, in this Chapter merely to 
present all the available data in the form in which it can be 
most easily made use of, in order to arrive at an independent 
and reUable judgment upon the various furnaces and processes 
of electric steel refining ; and each steel-maker will be expected 



174 ELECTEO-THERMAL METHODS 

to decide for himself which of these furnaces and processes is the 
most suited to his own particular requirements. 

The Heroult Furnace and Process. 

The most reliable figures relating to the Heroult furnace and 
process are those given by Osborne (see Chapter IV., p. 55) for 
the working of the 15 -ton furnace installed at the South Chicago 
Works of the U.S.A. Steel Corporation. These figures show that 
when using oxidised blown metal from the Bessemer converter of 
the following average composition : — 

Carbon '075 per cent. Phosphorus '095 per cent. 

Silicon '010 per cent. Sulphur '055 per cent. 

Manganese '075 per cent. 

1,350 kw. applied for one and one-third hours, equal to 119 
kw. hours per ton of 2,000 tons, could produce a deoxidised steel, 
low in sulphur and phosphorus, and within reasonable limits of 
practically any analysis required. The physical tests of these 
steels showed 35,000 to 47,000 lbs. for elastic Umit, 60,000 to 
70,000 lbs. for tensile strength, and 25 per cent, to 30 per cent, 
elongation. 

Independent data from MetalL and Chem. Engineering, 
quoted in the course of the same Chapter, showed a lower con- 
sumption of 103*8 kw. hours per ton of 2,204 lbs., for this same 
South Chicago furnace, with an average composition for eight 
successive heats of carbon '40 per cent., sulphur '029 per cent., 
phosphorus '030 per cent. 

As regards CostSy the consumption of electrodes at South 
Chicago is stated to amount to 6 lbs. carbon per ton of finished 
steel, and the cost of roof and hearth repairs is placed at the low 
limit of 6 cents per ton. 

Figures given by Eichoff, for the operation of a 8-ton Heroult 
furnace at the works of Eichard Lindenberg et Cie at Remscheid, 
show a power consumption of 200 kw. hours per metric ton, when 
using highly oxidised steel charged hot from a Wellman open- 
hearth f uro^ice. The raw material in this case contained on the 



POWEE CONSUMPTION AND RUNNING COSTS 175 

average '01 per cent, phosphorus ; this was reduced by the electric 
refining process to an average of "004 per cent., while the sulphur 
in the finished steel fluctuated between "007 per cent, and '012 
per cent. The above figures indicate that when molten metal 
from the Bessemer converter or Wellman open-hearth furnace is 
employed as raw material, the melt requires between 100 and 200 
kw. hours to complete the refining process, the power consumption 
being lowest in the larger furnace. 

As regards the average power consumption of furnaces working 
with cold scrap, the melting and refining process being carried out 
with two slags, the following figures were given in Chapter IV. 
for the output of a 2J-ton Heroult furnace at La Praz, France, 
during the week ending December 24th, 1911. 

Total metal refined, 62 tons 14 cwts. in 26 heats, equal to 
126 hours. Average power consumption for week, 528 kw. hours 
per metric ton. Lowest power consumption for week, 459 kw. 
hours per metric ton. 

Taking the cost of power at South Chicago at J cent, per kw. 
hour, we find that the energy required to carry out the electric 
refining process at this place represents only an addition of 
between $0*50 and $1*00 per ton to the cost of the finished steel, 
while the costs for electrodes and repairs would not add more 
than 10 cents per ton to the above figures. 

At SheflSeld, where the cost of electric power (as generated 
from coal by the Corporation Electricity Works) is '48 penny 
per kw. hour, the cost of refining molten metal will probably 
run between 4«. 6d. and 8«. 6d. per ton, and when cold scrap is 
used as raw material for the electric furnaces, the costs will rise 
to between 19^. and 21^. 6d, per ton. 

The Oirod Furnace and Process. 

The figures for the power consumption and working costs of 
the Girod furnace and process given in Chapter V. were suppUed 
by the owners of the patents, and are based upon the work at 
Ugine. They are doubtless not so convincing as independent 



176 



ELECTRO-THERMAL METHODS 



test results, but may be regarded as trustworthy. It must be 
pointed out that the more reliable estimates are based on the use 
of cold scrap as raw material of the refining operation, Girod 
believing that the quality of the steel produced is superior when 
starting with cold metal. The power consumption was recorded 
at the terminals of the furnace, and included smelting, refining 
and finishing a charge of cold scrap. It amounted to 850 kw. 
hours for a 3-ton furnace, and to 750 kw. hours for a lO-ton 
furnace. The figures, of course, varied with the composition of 
the charge, and according to the quality of the steel produced. 

The consumption of electrodes per ton of steel made was 
about 8 to 9 kgs. for the 8-ton furnace, and 8 to 10 kgs. for the 
10-ton furnace. 

The following estimates of costs are based on the Ugine 
results, and upon the prices of raw materials, rates of pay, etc., 
obtaining in the south-east district of France. 

Table XXXVIL 
Cold Charges. 



3-ton furnace. 



Raw Materials, 

Scrap— 1,100 kgs. at 75 frs. per 

1,000 kgs 

Slags . .• . • • . • 

Deoxidising additions and recarburisa- 

tion 

Producing Costs. 

Electric power— 850 and 750 kw. hours 

at 2 cents per kw. hour 
Electrodes, at 320 frs. per 1,000 kgs. 

Wages 

Maintenance and repairs per 1,000 kgs. 

Total cost, in frs. per 1,000 kgs. . 




10- ton furnace. 



82-50 
2-30 

3-50 



15-00 
3-50 
1-50 
8-00 



88-30 



28-00 



116-30 



POWER CONSUMPTION AND RUNNING COSTS 177 



Table XXXVUI. 
Molten Charges. 



Raw Materials. 

Liquid steel (4 per cent, loss in heating) 
1,040 kgs. at 80 f i s. per ton 

Slags 

Deoxidising additions .... 

Cost of Production, 

Electric power — 275 and 200 kw. hours 

at 2 cents per kw. hour 
Electrodes, 3 to 4 kgs., at 320 francs . 
Wages, 8 heats in 24 hours . 
Maintenance and repairs of the furnace 

Total cost, in frs. per 1,000 kgs. 
of steel 




10- ton furnace. 



83-20 
200 
3-50 



88-70 



400 
1-25 
100 
2-50 



8-75 



97*45 



These estimates do not include the expenses for ingot moulds, 
superintendence and laboratory charges, depreciation and general 
charges, which vary too considerably to allow a good average to 
be established. 

As regards the chemical composition of the raw materials and 

finished steel, the following are the average tests of the scrap 

material used and refined metal produced, at the Ugine Electric 

Steel Works : — 

Tabi^ XXXIX. 



Scrap Material. 


Finished Steel. 






Per cent. 




Per cent. 




Carbon . 


. -35 


Carbon 


. ^04 to 1^50 




Silicon . 


. -20 


Silicon . 


. -20 




Manganese 


. -70 


Manganese . 


•30 




Sulphur . 


•095 


Snlphnr 


015 




Phosphorus 


•095 


Phosphorus . 


•015 



The physical tests of the steel produced at Ugine by the Girod 
furnace and process range from 39,000 lbs. up to 114,000 lbs. 



E.T.M. 



N 



178 



ELECTEO-THERMAL METHODS 



for elastic limit ; from 60,000 lbs. up to 142,000 lbs. for tensile 
strength; and from 33 per cent, down to 9 per cent, for 
elongation under stress. 

The Stassano Furnace and Process. 

The following figures are given in Chapter VI. for the power 
consumption and working costs of the Stassano furnace and 
process as worked at Turin ; in each case cold scrap being used 
for charging the furnaces : — 

Table XL: 



200 h.p. Furnace. 


Power Consamption. 


Output. 


Steel for Projectiles . 
Mild Steel for Castings 


1,250 kw. hours per metric ton . 
1,260 kw. hours „ „ 


653 kgs. 
730 kgs. 


1000 h.p. Furnace, 






Steel Ingots for Projectiles 


958 kw. hours per metric ton . 
918 kw. hours „ „ 


3,900 kgs. 
3,900 kgs. 



As regards the consumption of electrodes and costs for 
refractory materials for linings, etc., the trials at Turin gave the 
following figures per ton of steel produced : — 

Electrodes . . .10 kgs. 2s. 6d. 

Refractory materials . . . 8«. O^d. to 12*. Id. 

A complete estimate of costs based on the trials at Bonn in 
Germany gave the following figures : — 

Per metric ton 

Table XLI; of cast steel. 

£ s. d. 

(1) Raw materials ; including additions of chromium 



to finished steel ... 

(2) Electric power (1,000 kw. hours at 

per kw. hour) 

(3) Refractory materials for liniugs 

(4) Labour 

(5) Interest and depreciation 

(6) Electrodes .... 

(7) Water for cooling purposes 



3 9 5 



536 penny 



2 


4 


8 


11 


10 





9 11 





4 


11 





2 


6 








6 


£7 


3 


9 



POWER CONSUMPTION AND RUNNING COSTS 179 



As regards the chemical and physical tests of the steel produced 
in the Stassano furnace, the following figures were given by 
Gatani in the paper read before the Iron and Steel Institute 
in London in October, 1911 : — 

Table XLII. 
Chemical Tests. 



Carbon. 


Silicon. 


Sulphur. 


Phosphorus. 


Manganese. 


Per cent. 

•235 
•207 
•360 


Per cent. 

•195 
•236 
•140 


Per cent. 

•047 
•043 
•052 


Per cent. 
•031 
•027 
•036 


Per cent. 

•546 
•421 
•486 



Physical Tests of the same Steels. 



No. 


Tensile strength 
in lbs. per sq. in. 


Elongation, 
per cent. 


1 
2 
3 


(Average) 61,726 
(Average) 58,462 
(Maximum) 63,355 


18-2 
19-0 
19^4 



The following are the average test results of steel made in the 
1,000 h.p. furnace and intended for projectiles : — 

Table XLIII. 
Chemical Tests. 



No. 


Carbon. 


Silicon. 


Sulphur. 


Phosphorus. 


Manganese. 


1 
2 


Per cent. 

•310 
•450 


Per cent. 
•242 
•061 


Per cent. 
•037 
•039 


Per cent. 

•023 
•029 


Per cent. 
•877 
1211 




Physical Tests. 






No. 


Tensile strength 
in lbs. per sq. in. 


Elongation, 
per cent. 






1 
2 


82,302 
99,330 


21-4 
171 





n2 



180 ELECTEO-THEEMAL METHODS 

The Ejellin and BdcUing-Bodenliaiuer Furnace and Process. 

The figures given in Chapter YII. show that, under the most 
favourable conditions, steel can be "melted" in the Kjellin 
furnace with an expenditure of 590 kw. hours per metric ton, but 
that the maintenance of the heat during the "killing" or 
degasifying period, adds from 60 to 200 kw. hours to this total. 

Tests made with a 125-kw. furnace of the original Kjellin 
type have shown that 1 metric ton of ordinary tool steel can be 
made with an expenditure of 650 kw. hours, while the highest 
grade steel requires from 750 to 800 kw. hours. 

As regards the power consumption and costs of operating the 
" combined " or Rochling-Rodenhauser type of induction furnace 
very full estimates and costs figures are available. According to 
Harden, when molten metal from the Bessemer converter is 
charged into the furnace, only from 125 to 150 kw. hours are 
required per ton of finished steel, and 180 kw. hours may be 
taken as a good average. 

Yom Baur, in a letter published in the issue of the journal 
named below,^ gives 200 to 250 kw. hours per metric ton for the 
work of a 10-ton furnace refining basic Bessemer steel, which 
contained before treatment in the electric furnace '08 per cent, 
phosphorus and "09 per cent, sulphur and only one-tenth of 
these amounts after the refining operation. According to the 
same authority, the E.E. type of induction furnace will melt 
cold scrap with an expenditure of 580 kw. hours per ton, and 
the following estimates of the conversion costs of a 2-ton furnace 
operated at Volklingen were given by him in a paper read in 
1911 before the American Foundrymen's Association. 

Table XLIV. 



700 kw. hours for melting at '6 per cent, perkw. 

hour . . $4-20 

200 kw. hours for refining at '6 per cent, per kw. 

hour . . . . . . . . 1*20 



Per long 
ton. 



15-40 



Metallurgical and Chemical Engineering y January, 1912. 



POWER CONSUMPTION AND RUNNING COSTS 181 

Table XLIV. — continued. 

Per long 
ton. 

Fluxes, etc., roll scale 22 lbs., lime 77 lbs., 
fluorspar 1 libs. , sand 20 lbs. , f erro-manganese 
8-8 lbs. . -44 

Loss of fluxes owing to quarter of all metal 

remaining in the hearth . ... *16 

Labour (at American rates of pay), 2 to 3 men . 1'50 

Tools, repairs and lining *67 

Depreciation 10 per cent., interest 5 per cent, on 
$11,000 for 300 days, 6 tons per day of 
12 hours. $1695 -i- 1800 = . . . '94 

Auxiliary apparatus (cooling air for transformer) *04 

Total $915 
Adding this, we get : — 

Raw materials ..... 12*60 

Conversion costs . . . , 9*15 



Cost of one ton electric steel ready to pour . . $21;75 

To this cost must be added a slight licence fee per ton, depend- 
ing on the output. Time of heat, about four to four and a 
quarter hours. 

Working with hot metal (drawn from the blast furnace, 
mixer, cupola, or other type of furnace), the consumption of 
power is, of course, considerably reduced, and the following 
figures are given by Vom Baur in the paper referred to above. 

Table XLV. 

Cost of refining hot metal tdk^n from the Wellman Mixer at 
Dommeldingen allowing for American conditions, and for a 6'ton 
furnace : — 

Raw materials ...... $12*00 

Oxidation loss 3 per cent. .... '36 

$12-36 

Current — 280 kw. hours at *6 cent per kw. 

hour ....... 1*68 

Fluxes, etc '60 

Labour '50 

Tools, repairs and lining .... '64 



182 ELECTEO-THEEMAL METHODS 

Table XLV. — continued. 

Depreciation 10 per cent., interest 5 per cent. 

on $17,000 for 300 days at 40 tons per 

day of 24 hours, $2,550 -^ 12,000 tons = '22 

Auxiliary apparatus *06 

Total $1606 



Cost of preliminary refining, about . . 3'00 



Total cost of 1 ton of electric steel read v to 

pour $19*06 

Time of each heat about 2i hours. 



'2 



The estimated cost of refining hot metal, melted in the 
cupola, and consisting mainly of steel scrap, having about 2 per 
cent, carbon in the resultant mixture, is as follows : — 



Tablk XLVI. 




Raw materials . , . . . . |14"00 




Total oxidation loss, 8 per cent. . . . 1'12 






$1512 


Conversion cost similar to the above . 


4-90 


Cost of preliminary melt in the cupola, about 


300 



Cost of 1 ton of electric steel ready to pour . $23*02 

Time of each heat about 3^ hours. 

A more detailed estimate of. cost for English conditions of 
work was given by Kjellin in a paper contributed to the Niagara 
Falls Meeting of the American Electro-chemical Society, held in 
May, 1909. The production cost of steel for rails in a 7-ton 
three-phase Eochling-Eodenhauser furnace was given in this 
paper as 74s. 8d. per ton, and for soft boiler-plate as 79s. 3d. 
per ton. 

Aa a final estimate of power consumption and costs, that 
given by Thieme in an article contributed to the journal named 
below ^ may ba quoted. The estimate is for steel produced in a 

1 ElectrotechniscJie Zeitschrift^ September 8, 1910. 



POWEE CONSUMPTION AND EUNNING COSTS 183 

three-phase E.E. furnace, of 5-ton capacity, using fully-blown 
molten raw material containing 0*8 per cent, phosphorus ; 
0*8 per cent, sulphur and "12 per cent, carbon, and with 
power costing 4*5 pfg. per kw. hour. It is assumed that this 
furnace can produce annually 10,000 tons of finished steel, in 
250 working days of 8 heats per day. 



Table XLVII. 



Marks per Ton of 
Finished Steel. 



Depreciation on 10,000 marks 1*00 

Power consumption, 280 kw. hours . . . 12*60 

Materials for slags, etc 2'25 

Linings and repairs 2*50 

Wages '75 

Air-blast for cooling transformer coils . . *21 



19-31 marks 

This total, equivalent to 19«., is one for running costs only, 
no estimates for the cost of raw materials, or for the interest and 
royalty charges having been included in it. 

As regards the degree of purification effected by the Eochling- 
Eodenhauser type of furnace, the average of the three tests of 
rail-steel given by Harden shows '035 per cent. S. ; '048 per 
cent. P., and a tensile strength o»f 52*5 tons per square inch. The 
average of the tests given by Vom Baur for various steel products 
shows '008 per cent. S. ; '0095 per cent. P., and an average tensile 
strength of 89,600 lbs. per square inch. 

The corresponding chemical tests, for the raw materials used 
in making these steels, are not given. 

The Keller Furnace and Process. 

The only figures for the power consumption and running costs 
of the Keller electric refining furnaces are those emanating from 
the patentee, and published in Chapter VIIL, p. 131. They 
relate to the work done with the 8-ton furnaces of the earlier type 
at Unieux in 1908, and are based on the use (as raw material) of 



184 ELECTRO-THEEMAL METHODS 

molten metal from a Martin open-hearth furnace. The follow- 
ing are the figures as given by Keller in one of his numerous 
papers : — 

Table XLVIII. 

Molten metal charged, 7,500 kgs. 

Composition of ditto ; carbon, '15 per cent. ; sulphur, *06 per cent. ; 

phosphorus, '007 per cent. 
Mean ix)wer consumption, 750 kw. 
Carbon contents desired, *45 to *50 per cent. 
Time of refining operation, 2 hours 45 minutes. 
Composition of finished steel. Carbon, '443 per cent. ; sulphur, 

'009 per cent. ; phosphorus, *008 per cent. 
Power consumed per metric ton, 275 kw. hours. 
Electrode consumption, 10 kgs., costing, at 40 frs. per 100 kgs., 

4 frs. per ton. 

No figures showing the power consumption or running costs of 
the later type of Keller furnaces have been published. 

The Frick Furnace and Process. 

The power consumption of the Frick electric induction 
furnace, according to Lyman (see Chapter IX., p. 139), is600kw. 
hours per ton for melting the cold scrap, and 180 to 200 kw. 
hours per ton for refining, a total of 780 to 800 kw. hours per 
ton of finished steel. 

The Hiorth Foruace and Process. 

According to the figures given by Richards (see Chapter IX., 
p. 145), 580 to 550 kw. hours are required to melt one ton of 
pig-iron and Walloon bar-iron in the Hiorth induction furnace, — 
and under regular conditions of work, 150 kw. to 170 kw. hours 
are required to complete the refining operation. This equals 
a total of 680 to 720 kw. hours used per ton of cold metal 
charged. In the melt of which full details are given however, 
the power consumption was 790 kw. hours per ton of metal. 

The Colby Furnace and Process. 

The trials of the small experimental furnace at Tacoma, 
U.S.A., showed a power consumption of between 605 and 



POWEE CONSUMPTION AND EUNNING COSTS 185 

825 kw. hours per metric ton of metal poured (see Chapter X., 
p. 157). 

In order to enable the more important figures given in the 
course of this Chapter to be compared, they have been reduced to 
a common basis, and are presented in Tables XLIX and L. 

Table XLIX., showing the Power Consumption of the various 
furnaces is most instructive and will repay careful study. 

Table L., giving the figures for the Chemical and Physical 
Tests of the raw material used and finished steel, must be studied 
in the light of the footnote attached to the Table. 

The Running Costs cannot be compared satisfactorily by any 
method of tabular statement, since the costs of raw materials and 
other data upon which the estimates for the different furnaces 
and processes are based, vary so greatly. It may be stated, 
however, that other charges being equal, the furnace and proceds 
that has the smallest power consumption will prove the cheapest 
to work, for the cost of power in every case is one of the main 
items in the total operating costs. The cost of linings and repairs 
is another important item, which varies greatly with the different 
types of furnace. It is perhaps necessary to emphasise the fact 
that this has a considerable influence upon the total running 
costs of the installation. Frequent repairs mean that frequent 
stoppages of the furnace are necessary in order that these repairs 
may be carried out, and these stoppages not only cause loss of 
heat, but also diminish the output of the furnace, and conse- 
quently increase the interest and depreciation charges per ton of 
finished steel. 

This is one feature of the repairs question that is some- 
times overlooked by patentees and electro-metallurgists without 
practical works experience, who have failed to realise that a large 
and steady output is an essential condition of success in all furnace 
operations when carried on upon an industrial scale. 



186 



ELECTRO-THEEMAL METHODS 



Table XLIX. 

Power CouBUMPXioN m kw. hours per Metric Ton (2,204 lbs.) op Steel 

Produced. 



Type of 
Furnace. 


Cold charges 
composed of 


Molten charges 
from 


efor 
barges. 


• 


Pig-iron 
and Wal- 
loon iron. 


• 

o 


s 


Wellman 

open 
hearth. 


Martin 

open 

hearth. 


• 

08 

"a 

s 
o 


Ayerag 
molten cl 


Heroult . 


459 
528 




493 


104 
133 


200 






146 


Girod 


750 
850 




800 




200 
275 






237 


Stassano 


918 

958 

1,000 

1,250 

1,260 




1071 












Kjellin . 


650 
790 
800 




747 












Rochling- 
Rodenhauser 


640 

780 
900 




773 


125 
150 
200 
250 


280 




280 


214 


Frick . 


780 
800 




790 












Keller . 













275 




275 


Hiorth . 


"^■^ 


680 
720 
790 


730 












Colby . 


605 
825 




715 













POWER CONSUMPTION AND RUNNING COSTS 187 



Table L. 
Chemical and Physical Tests op Steel Produced. 





Chemical Tests. 


Physical Tests in lbs. per sq. in. 


Type of Furnace. 


Per cent. 
Carbon. 


Per cent. 
Sulphur. 


Per cent. 
Phosphorus. 


Elastic 
Limit. 


Tensile 
Strength. 


Elon- 
gation 
Per cent. 


Heroult . 


•40 


■055 
•029 
•009 
•012 


•095 
•030 
•004 


35,000 

47,000 


60,000, 
70,000 


25 

▼ 

30 


Girod . 


•350 

•040 

1^500 


■095 
•015 


■095 
•015 


39,000 
114,000 


50,000 
137,000 


9 

▼ 

33 


Stassano. 


•267 
•380 


•048 
•038 


•031 
•026 




61,300 

4- 
90,816 


18 

1 
19 


Rochling- 
Rodenhauser 




'090 
•009 
•035 
•008 


■080 
•008 
•048 
•0095 




89,600 
117,600 





Keller . 


'15 
•44 


■060 
•009 


•007 
•008 









Note. — The chemical tests in the above Table represent the averages 
for particular classes of steel. The tests in italics show the average 
composition of the raw materials used. The tests immediately below 
these represent the tests of the steel produced from these same raw 
materials. 

The physical tests are the highest and lowest figures for the steels 
produced by each type of furnace ; some of these being special alloy 
steels. 



APPENDIX. 



I. Lists of Electric Furnaces for Iron and Steel Production in 
Operation or under Construction in 1912. 

II. List of English and Foreign Patents relating to Electric 
Furnaces for Iron and Steel Production granted from 1898 to 
1911. . 

III. Abstracts and Beprints of the early Patents relating to 
Electric Furnaces for Iron and Steel Production. 

IV. Abstracts of Papers and Notes on Electric Steel Refining, 
and on Electric Furnaces. 



I. List of Electric Furnaces for Iron and Steel 

Production. 

A. Iron Smelting Furnaces} 

In September, 1912, the following furnaces of the Swedish 
type were in operation, and in course of erection, in Europe :— 

Completed — 

TroUhatten, Sweden, 1 furnace . . . 2,500 h.p. 

Domnarfvet, „ 1 „ . . . 3,500 „ 

Hagfors, „ 2 furnaces of 3,000 h.p. 6,000 „ 

Hardanger, Norway 1 furnace . . . 3,500 „ 

Under Construction or Planned — 

Hagfors, Sweden, 1 furnace . . . 3,000 h.p. 

Nykroppa, „ 3 furnaces of 3,000 h.p. 9,000 „ 

Hardanger, Norway 1 furnace . . . 3,000 „ 

Arendal, „ 3 furnaces of 3,000 h.p. 9,000 „ . 

Switzerland . . 1 furnace . . . 2,500 „ 



Total, furnaces for . . 42.000 h.p. 



From Metallurgical and^Cfiemical Engineering, 



APPENDIX 



189 



B. List of Heroult Steel Refining Furnaces, under Construction 

or in Operation, January, 1912. 







Size of 




Country. 


Firm. 


Furnace. 


Method of Melting. 






Tons. 




England 


Edgar Allen & Co., Ltd., 


2i 

^2 


Tilting basic open 




Sheffield. 




hearth. 




Skinningrove Iron Co., 


15 

• 


Talbot. 




Yorkshire 






- 


Vickers, Ltd., Sheffield. 


3 


Melting scrap in 
electric furnace. 


• 


Vickers, Ltd., Sheffield. 


8 


Melting scrap in 
electric furnace. 




Thomas Firth & Sons, 


2i 


Melting scrap in 




Ltd., Sheffield. 




electric furnace. 




Tiake & Elliot, Braintree. 


2i 


Melting scrap in 
electric furnace. 


Austria- 


Kaernthner Eisen & 


5 


Melting scrap in 


Hungary 


Stahlwerke. 




electric furnace. 




Gebr. Bohler & Cie, A. G., 


2i 


Melting scrap in 




Kapfenberg. 




electric furnace. 




Gehr. Bohler & Cie, A. G., 


4 


Melting scrap in 




Kapfenberg. 




electric furnace. 




Briider Tiapp, Rotten- 


6 


Melting scrap in 




mann. Works Steier- 




electric furnace. 




mark. 








Banner & Co., Juden- 


2 


Melting scrap in 




berg. 




electric furnace. 




Royal Himgarian Arsenal. 


2 


Melting scrap in 
electric furnace. 


Belgium 


Soci6t6 des Usines M^tal- 
lurgiques du Hainaut, 
CouiUet. 


5 


Basic open hearth. 




Soci6t6 Anonyme Ougr6e- 


5 


Basic open hearth. 




Marihay^, near Li^ge. 






France 


Soci6t6 Electro-Metallur- 


2i 


Melting scrap in 




gique Fran^aise, ^a 




electric furnace. 




Praz, Savoie. 








Acieries du Saut du Tarn, 


5 


Basic open hearth. 




St. Ju^ry. 








Usine M6tallurgique de la 


5 


Basic open hearth. 




Basse Loire, Trignac. 







190 



APPENDIX 



B. lAat of Heroult Steel Refining Furnaces, under Construction 
or in Operation, January, 1912 — continued. 



Country. 


Firm. 


Size of 
Furnace. 


Method of Melting. 






Tons. 




Germany 


Deutscher Kaiser Stahl- 
werke, Bruckhausen. 


6 


Basic open hearth. 




Deutscher Kaiser Stahl- 


6 


Basic open hearth. 




werke, Bruckhausen. 








Deutscher Kaiser Stahl- 


25 


Basic open hearth. 




werke, Bruckhausen. 








Stahlwerke Thyssen 


7 


Basic open hearth. 




Hagendingen (Lothr.). 








Stahlwerke Thyssen 


7 


Basic open hearth. 




Hagendingen (Lothr.). 








Stahlwerke Richard Lin- 


2 


Tilting basic. 




denberg, Remscheid- 








Hasten. 








Stahlwerke Richard Lin- 


3 


Open hearth. 




denberg, Remscheid- 








H as ten. 








Bisujarckhiitte, Upper 


1 


Melting scrap in 




Silesia. 




electric furnace. 




Bismarckhiitte, Upper 


3 


Melting scrap in 




Silesia. 




electric furnace. 




Mannesmann Rohren 


3 


Melting scrap in 




Werke, Saarbrucken, 




electric furnace. 




Burbach. 








Rombacher Hiittenwerke, 


22 


Open hearth. 




Rombach. 








Rombacher Hiittenwerke, 


3 


Open hearth. 




Rombach. 








Deutscher Luxemburg- 


7 


Open hearth. 




ische, Dortmund. 








Deutscher Luxemburg- 


7 


Open hearth. 




ische, Dortmund. 






Italy . 


Societa Tubi Mannes- 


6 


Melting scrap in 




mann, Dalmine. 




electric furnace. 




Society Tubi Mannes- 


6 


Melting scrap in 




mann, Dalmine. 




electric fiimace. 


Russia . 


Imperial Steel Works, 
Obuchow, St. Peters- 


^1 
02 


Open hearth. 




burg. 







APPENDIX 



191 



B. List of Heroult Steel Refining Furnaces, under Construction 
or in Operation, January, 1912 — continued. 



Country. 


Firm. 


Size of 
Furnace. 


Method of Melting. 






Tons. 




Russia — cont 


AktiengeseUschaft der 


3 


Molten Martin 




Hutten-&-Tnechanischen 




steel. 




Werke, Sormovo. 








Soci6t^ G^n^rale des Hts. 


3 


Molten Martin 




Fourneaux & Acieries 




steel. 




en Russie, Makejewka. 






Sweden 


Aktiebolaget Hereults 


6 


Meltiug scrap in 




elektriska Stal, Kortf ors. 




electric furnace. 


Switzerland . 


Georg Fischer, Schaff- 


li 


Melting scrap in 




haiisen. 




electric furnace. 


Canada 


Electro Metals, Welland, 


H 


Melting scrap in 




Ontario. 




electric furnace. 




Electro Metals, Welland, 


5 


Melting scrap in 




Ontario. 




electric furnace. 


United States 


United States Steel Cor- 
poration, S. Chicago. 


15 


Bessemer. 




United States Steel Cor- 


15 


Basic open hearth. 




poration, Worcester. 








Firth-Stirling Co., Syra- 


2i 


Melting scrap in 




cuse, New York. 




electric furnace. 




Firth-Stirling Co., Syra- 


5 


Melting scrap in 




cuse, New York. 




electric furnace. 




Halcomb Steel Co., Syra- 


5 


Tilting basic open 




cuse, New York. 




hearth. 




Crucible Steel Co., of 


5 


Basic open hearth. 




America, Pittsburg, Pa. 








Crucible Steel Co., of 


5 


Basic open hearth. 




America, Pittsburg, Pa. 






Mexico 


Cie. Mexicano Aciero & 


4 


Melting scrap in 




Productos Chemicos. 




electric furnace. 




Cie. Mexicano Aciero & 


4 


Melting scrap in 




Productos Chemicos. 




electric fui'nace. 



192 



APPENDIX 



C. List of Girod Steel Refining Furnaces. 




Country. 



France . 



England 



Germany 



Austria . 



Hungary 

Switzerland. 
Italy . 

Russia 
America . 



Cie. des Forges et Acieries Elec- 
triques Paul Girod, Ugine . 



Capacity of Furnaces. 



Operating. 



Messrs. Rubery, Owen & Co., 
Darlaston 

Stahlwerke Becker, Krefeld-WiUich 
GiitehoffnuDgshiitte, Oberhausen 
Fried, Krupp, A.G. ; Essen-Ruhr 
Oberschlesische Eisen-Industrie, 
A. G., Gleiwitz .... 

Sterrische Gusstahlwerk Danner & 
Co., Judenburg (Styrie) . 

Ternitzer Stahl u. Eisenwerke von 
Schoeller & Co., Ternitz, a.d. 
Sudbahn 

Diosgyorer Eisen & Stahlwerke, 
Diosgyor 

Oehler & Cie, Aarau 

Gio. Ansaldo Armstrong & Cie, a 
Genes ..... 

Usines Poutiloff, a St. Petersbourg 

The Simonds Manufacturing Co., 
Chicago . . . . . 

Totals 



Tons. 

12 
12 

3 

3 

2 

1 

1 

2 



3 

3 

12 

8 



2 



2 
2 



1. 

2 






66| 

(16 
Furnaces.) 



Erecting 



Tons. 



8 



20 

(5 
Furnaces.) 



APPENDIX 



198 



D. Kjellin and RocMing-Bodenhauser Electric Steel Refining 
Furnaces, Working or under Construction, on April 1st, 1912. 





Capacity in kgs. 


Type, 


Power. 


Product. 




Country and Firm. 




^ § 


Charges. 




Work- 


a> • .2 
13 S iri 












ing. 


OQ 










Germany and Luxem- 














burg — 














Bergische Stahl- 


5,000 




Rochling 


IPh. 


High- 


Hot 


industrie, Rem- 






Roden- 




grade 


Martin 


scheid 






hauser 




steels. 


steel. 


Eicher Hiitten- 


3,500 




Do. 


Do. 


High- 




verein 










grade 




Le Gallais Metz & 


3,500 




Do. 


Do. 


steels 




Cie. • 










and 




Dornineldingen 


3,500 




Do. 


Do. 


steel 
castings. 


■ ■• 


Eberle & Co., Augs- 




3,500 


Do. 


3 Ph. 


High- 


Cold 


burg 










grade 
steels. 


scrap. 


Grohman & Co., 


500 




Do. 


1 Ph. 


Acid 


Do. 


Wesseling b/Koln 










steel 
castings. 




Oberschlesische, 


],500 




Kjellin 


Do. 


Do. 


Do. 


Eisenindustrie 














A. G. Gleiwitz 






• 








Peiner Walzwerk, 




4,500 


Rochling 


2 Ph. 


Molten 


Do. 


Peiner 






Roden- 
hauser 




Ferro- 

Man- 

ganese. 




Rochling'sche, 


12,000 





Do. 


IPh. 


High- 


Hot 


Eisen & Stahl- 










grade 


Martin 


werke, Volk- 


1,500 




Do. 


3 Ph. 


steels. 


steel. 


lingen 


1,000 


4,000 


Do. 


IPh. 


Molten 

Ferro- 

Man- 

ganese. 


Cold 
scrap. 


Austria — 














Braun*s Sohne, 


400 




Kjellin 


Do. 


File- 


Do. 


Vocklabruck 










steel. 




Poldihutte, Kladno 


4,500 




Do. 


Do. 


High- 
grade 
steels. 


Hot 

Martin 

steel. 



E.T.M. 







194 



APPENDIX 



D. Kjellin and Rochling-Eodenhauser Electric Steel Refining 
Furnaces, Working or under Construction, on April 1st, 
1912— continued. 



• 


Capacity in kgs. 

• 


Type. 


Power. 


Product. 




Country and Firm. 




^ § 


Charges. 




Work- 


•^G-S 












ing. 


c o o 










A ustria — continued. 














Acieries de la Ma- 


3,000 




Roclding 


IPh. 


High- 


Hot 


rine et d Home- 






Roden- 




grade 


Martin 


court, St. Cha 






hauser 




steels. 


steel. 


mond 














Altiforui Gregorini, 


1,600 


— 


Kjellin 


Do. 


Do. 


Hot 


Lovere 












scrap. 


Russia — 








« 






Kronwerke, Sla- 


— 


1,000 


Rochling 


3 Ph. 


Do. 


Cold 


toust 






Roden- 
hauser 






scrap. 


Sweden — 














Eisenwerk, Dom- 


1,500 




Kjellin 


IPh. 


Do. 


Do. 


narlvet, Gysinge 














Norway — 














Stavanger Elektro- 




4,000 


Rochling 


Do. 


Do. 


Hot 


stalverk, A. S. 






Roden- 
hauser 






scrap. 


Spain — 














Urigoilia e Hija 


1,500 




Kjellin 


Do. 


Do. 


Cold 


Araya 












scrap. 


Japan — 














Kaiserl, Stahlvverk, 




3,000 


Rochling 


2 Ph. 


Do. 


Hot 


Wakamatsu 


- 




Roden- 
hauser 






Martin 
steel. 


Mexico— 














Ricardo Honey, 


— 


2,500 


Do. 


3 Ph. 


Do. . 


Do. 


Mexico 














England — 














Jessop & Sons, 


1,800 




Kjellin 


IPh. 


Do. 


Cold 


Sheffield 












scrap. 



APPENDIX 



195 



D. Kjellin and Rdchling-Rodenhaaser Electric Steel Refining 
Furnaces, Working or under Construction, on April Ist, 
1 912 — continued. 





Capacity in kgs. 


Type. 


Power. 


1 

Product. 




Country and Firm. 




• 


Charges 




Work- 


'^ s r 












ing. 


a6% 

Kf. 










England — continued. 












The University, 


300 




Kjellin 


IPh. 


Experi- 




Sheffield 










mental 
furnace. 




United States — 














Crucible Steel Cast- 




2,000 


Rochling 


Do. 


Steel 


Cold 


ing Co., Lans- 






Roden- 




cas tinge. 


scrap. 


downe, Pa. 






hauser 








General Electric 




. 200 


Kjellin 


Do. 


Experi- 




Co., Schenectady 










mental 
furnace. 




Canada — 














Electric Steel Co., 






Do. 


Do. 


75 kgs. 


-^ 


Welland, Ontario 










(At pre- 
sent not 




m 










working). 





E. List of Keller Electric Steel Refining Furnaces, Working, or 

tinder Constniction, in February, 1912. 



Firm. 



Usines de la Societe des Etablissements Keller Leleux, 
at Li vet, Isere, France ...... 

Acieries Jacob Holtzer, at Unieux, Loire, France 

Ateliers de Constructions Electriques du Nord et de 
TEst, at Jumont, France . . . . . 

Technical Science Schools, Grenoble, France 



Capacity 
in kgs. 



Luxemburger Bergvverke & Saorbrucken Eisenhiitten, 
at Saarbrucken, Germany . . . . . 
Gebriider Sturam, at Neunkirchen, Germany 



Societa Anonyma Ferriere di Voltri, at Darfo, Italy 



3,500 
1,500 

3,500 
3 X 500 



3,500 
3,500 



3,500 
~oT" 



196 



APPENDIX 



II. Lists of English and Foreign Patents Relating to 
Electric Furnaces for Iron and Steel Production 

GRANTED 1898—1911. 

A. List of English Patents prepared by John E. Raivorthy Chartered 
Patent Agents Queen Anne's Chambers, 28, Broadtvay, 
London, S,W} 



No. of 
Patent. 



11604/98 



16293/00 

22584/00 
14486/01 

14643/01 

24234/01 

24235/01 
3912/02 
8288/02 

15271/02 
6950/03 



Date of Patent. 



23 May, 1898 



13 Sept., 1900 

21 May, 1900 
16 July, 1901 

18 July, 1901 

6 July, 1901 

6 July, 1901 
15 Feb., 1902 
9 April, 1902 

8 July, 1902 
25 March, 1902 



Patent Granted in 
Name or Names of 



Ernesto Stassano . 



John Imray (La 
Soci6te Electro- 
M^tallurgique 
Fran9ai8e) 

Charles Albert 
Keller 

John Imray (La 
Soci6t6 Electro- 
M^tallurgique 
Fran9aise) 

John Imray (La 
Soci6t6 Electro- 
M^tallurgique 
Fran9aise) 

Charles Albert 
Keller 

Charles Albert 

Keller 
Paul Louis Tous- 

saint Heroult 
Ernesto Stassano . 



Charles Albert 
Keller 

LaSoci^t^Electro- 
Mdtallurgique 
Fran^aise 



Subject-matter of Patent. 



Improvements in and connected 
with the electro - metallurgic 
production of iron, 8t.eel, and 
their alloys with chromium tung- 
sten, nickel, manganese, and the 
like. 

Improvements in electric furnaces. 



An electric furnace with two bed 

plates. 
Process and apparatus for the 

manufacture of wrought iron, 

steel, and cast iron by electric 

heating. 
Electric furnace arranged for 

being oscillated or tipped. 



Improvements in the obtainment 
of metals and alloys, and in 
furnaces to be employed therein. 

Improvements in the manufacture 
and tieatment of allovs. 

Improvements in electric furnaces. 

Improvements in and relating to 
the electrical smelting of ores 
and the refining of metals and 
to furnaces therefor. 

A new or improved process for the 
electric heating and refining of 
metals and other substances. 

Improved method of deoxidising 
and carburising molten iron or 
steel. 



* (1) The dates given, in all cases, are the dates of the patents. (2) The list 
covers only the names of patentees and inventions dealt with in the present 
volume, and does not include furnaces that have never received practical triaL 



APPENDIX 



197 



A. List oj English Patents prepared by John E. Raworthy Chartered 
Patent Agent, Queen Anne's Chambers, 28, Broadway, 
London, S.W. — continued. 



No. of 
Patent. 



7027/03 



3790/04 

4866/04 
25948/04 



6001/05 



13690/05 
14214/05 
14333/05 
23402/05 
25174/05 



25771/05 
3004/06 

9799/06 

10097/06 

12329/06 
13189/06 

16269/06 
17615/06 



Date of Patent. 



26 March, 1903 



15 Feb., 1904 

27 Feb., 1904 
8 July, 1904 



22 March, 1905 



4 July, 1904 
11 July, 1904 
11 July, 1905 
24 Dec, 1904 

4 Jan., 1905 



11 Dec, 1905 
11 Feb., 1905 

8 May, 1905 

30 April, 1906 

26 May, 1906 
5 Aug., 1905 

18 July, 1906 
4 Aug., 1906 



Patent Granted in 
Name or Names of 



Arthur George 
Bloxam (La 
Society Electro- 
M^tallurgique 
FraD9aise) 

Charles Albert 
Keller 

OttoFrick . 

La Soci^t^ M^tal- 
lurgique Fran- 
yaise 

T. S. Anderson . 



P. Girod . 

F. A. Kjellin 

P. Girod . 

P. Girod . 

Soci^t^ Anonyme 
E'ectro-M^tal- 
lurgique (Pro- 
cdd^s Paul 
Girod) 

0. Frick . 

La Soci^t^ Electro- 
M^tallurgique 
Fran9aise. 

E. A. A. Gronwall. 



0. Frick 



H. Rochling and 
W. Rodenhauser. 

La Soci^te Electro- 
Mdtallurgique 
Fran9ai8e. 

The Grondal Kjel- 



Ltd., and J. 



lin Company, 

id 

Harden. 
H. Rochling and 
W.Rodenhauser. 



Subject-matter of Patent. 



Improvements in the production of 
iron and steel. 



Improvements in and relating to 

electric furnaces. 
Improvements in electric furnaces. 
Improvements in the manufacture 

of steel. 

Improvements in the method of, 
and apparatus for, the smelting 
of ores, iron sand, and the like, 
and subsequent conversion into 
steel or other metals or alloys. 

Improvements in electric furnaces. 

Improvements in electric furnaces. 

Improvements in electric furnaces. 

Improvements in electric furnaces. 

Improvements in electric furnaces. 



Improvements in electric trans- 
former furnaces. 

Electric mixing furnace for mixing 
steel. 

Improvements in processes for 
heating, smelting, or reducing 
materials, and means for carrying 
out the same. 

Method of, and furnace plant for, 
reduction of arcs or the like by 
electric transformer furnaces. 

Improvements in and relating to 
electric furnaces. 

Improved manufacture of de- 
carburised cast iron. 

Improvements relating to electric 
induction furnaces. 



Improved means for obtaining 
thin liquid dross in electric fur- 
naces for metallurgical purposes. 



198 



APPENDIX 



A. List of English Patents jyrejyared by John E. Raworth, Chartered 
Patent Agent, Queen Anne's Chambers^ 28, Broadivay, 
London, S.W. — continued. 



No. of 
Patent. 



21416/06 

22619/06 

28370/06 
28959/06 

28960/06 
28961/06 

i29019/06 

29271/06 
; 1668/07 

3276/07 



4927/07 
6193/07 
7791/07 
8445/07 

10760/07 
11917/07 

24687/07 



Date of Patent. 



5 March, 1906 

18 Dec!, 1905 

12 Dec, 1906 
6 May, 1906 

2 June, 1906 

6 Nov., 1906 

19 Dec, 1906 

27 Dec, 1906 
26 Jan., 1906 

9 Feb., 1907 



26 Sept., 1906 
14 March, 1907 
3 April, 1907 
11 April, 1907 

8. May, 1907 

22 May, 1907 

6 Nov., 1907 



Patent Granted in 
Name or Names of 



F. A. Kjellin 

0. Flick 

A. Hiorth . 
A. Hiorth . 

A. Hiorth . 
A. Hiorth . 



The Grondal Kjel- 
lin Company, 
Ltd., and J. 
Harden.. 

0. Frick . . 

E. A. A. Gtonwall, 
A. R. Lindblad 
and 0. Stalhane. 

Soci^t^ Anonyme 
Electro - M^tal- 
lurgique (Pro- 
c^d^s . Paul 
Girod) 

F. M. Chaplet and 
Soci^t^ la Neo 
M^tallurgie . 

E. A. A. Gronwall, 
A. R. Lindblad 
and O. Stalhane 

£. A. A. Gronwall, 
A. R. Lindblad 
and 0. Stalhane 

The Grondal Kjel- 
lin Company, 
Ltd., and J. 
Harden. 

J. H. Reid . 



H. Rochling, J. 
Schoenawa and 
W.Rodenhauser 

C. A. Keller 



Subject-matter of Patent. 



Improvements in and relating to 
electrical furnaces. 

Improvements in electric trans- 
former furnaces. 

Improvements in electric furnaces. 

Improvements in the method of 
operating electrical smelting 
furnaces. 

Improved electrical induction fur- 
nace with electrodes. 

Improvements in the method of 
operating electrical smelting 
furnaces. 

Improvements in or relating to 
electric induction furnaces. 



Improvements in electric trans- 
former furnaces. 

Improvements in electric smelting 
furnaces. 

Improvements in the crowns or 
covers of electric furnaces. 



Improvementa in or relating to 
electric furnaces. 

Improvements in electric trans- 
former furnaces. 

Improvements in electiic trans- 
former furnaces. 

Improvements relating to electric 
furnaces. 



An improved process and apparatus 
for treating ore or like material 
by the aid of heat. 

Improvements in electrodes for 
resistance furnaces. 

Improvements in or relating to 
flexible electrical connection 
devices. [Note. — For use with 
electric furnaces.] 



APPENDIX 



199 



A. List of English Patents prepared by John E. Raworth, Chartered 
Patent A gent y Queen Anne's Chambers y 28, Broadway, 
London, ^.W, — continued. 



No. of 
Patent. 


Date of Patent. 


Patent Granted in 
Name or Names of 


Subject-matter of Patent. 


27556/07 


13 Dec, 1907 


H. Bochling and 


Improvements in the treatment of 






J. Schoenawa 


iron which is to be converted 








into steel. 


28542/07 


4 Jan., 1907 


A. Hiorth . 


An improved electrical induction 
furnace. 


3680/08 


21 Feb., 1907 


Karl Albert 


An improved method of reducing 






Fredrik Hiorth 


ores, principally iron ores. 


7188/08 


1 April, 1908 


Hans Nathusius 


Improvements in or relating to 






and Westdeut- 


electric furnaces. 






sche Thomas- 






. 


phosphatwerke 








G.m.b.H. 


■ 


7923/08 


9 April, 1908 


Hans Nathusius 


Improvements in or relating to 






and Westdeut- 


electric furnaces. 






sche Thomas- 








phosphatwerke 


- 




• 


Q-.m.b.H. 




12634/08 


12 June, 1908 


Charles Albert 


Improvements in or relating to 






Keller 


connections for the electrodes of 
electric furnaces. 


18513/08 


26 Feb., 1908 


Rochiing'sche 


Improvements relating to electric 






Eisen- und 


induction furnaces. 






S tahlwerke 








G.m.b.H. and 








Wilhelm Eo- 








denhauser 




21741/08 


14 Oct., 1908 


Charles Albert 


Improvements in or relating to 






Keller 


electric furnaces. 


6820/09 


22 Aug., 1908 


James Henry 
Eeid 


Improvements in electric furnaces. 


6821/09 


22 March, 1909 


James Henry 


Improved process for reducing iron 






Reid 


or other ores and refining the 
metal obtained. 


8194/09 


5 April, 1909 


The Grondal Kjel- 


Improvements relating to electric 






lin Company, 


induction furnaces. 






Ltd., and 
Johannes Har- 
den. 




9508/09 


21 April, 1909 


Albert Edwards 


Improved process of refining metals 






Greene 


and alloys. 


11480/09 


16 May, 1908 


Albert Hiorth and 


Improvements in electric induction 






Carl Wilhelm 


furnaces. 






Soderberg 




12337/09 


23 Sept., 1908 


James Henry 


Improvements in processes of 






Reid 


separating and refining metals. 


13295/09 


7 June, 1909 


Hans Nathusius 


Improvements in or relating to 






and Westdeut- 


electric furnaces. 






sche Thomas- 






- 


phosphatwerke 








G.m.b.H. 





200 



APPENDIX 



A. List of English Patents prepared by John E. Raworth, Chartered 
Patent Agent, Queen Anne's Chambers, 28, Broadway, 
London, S.W. — continued. 



No. of 
Patent. 


Date of Patent. 


Patent Granted in 
Name or Names of 


Subject-matter of Patent. 


24839/09 


3 Feb., 1909 


James Henry 


Improved process for recovering 






Reid 


precious metals from ores. 


25244/09 


2 Nov., 1909 


Fredrik Adolp 


Improvements in or relating to 
the treatment of ores in blast 






Ejellin 








furnaces. 


26588/09 


6 May, 1909 


Socidte Anonyme 


Improvements in the process of 






Electro - Mdtal- 


refining steel. 






lurgique (Pro- 








c^d^s Paul 


• 






Girod) 




26251/09 


12 Nov., 1909 


Johannes Harden 


Improvements in or relating to 
electric furnaces. 


26266/09 


12 Nov., 1909 


Johannes Harden 


Improvements relating to electric 
furnaces. 


27003/09 


20 Nov., 1909 


Soci^te Anonyme 


Improvements in the process of 






Electro-M^tal- 


refining steel. 






lurgique (Pro- 








c^d^s Paul 








Girod) 




3421/10 


26 Aug., 1909 


Soci^t^ Anonyme 


Method of supplying electric 






Electro-M^tal- 


furnaces with tri-phase current. 






lurgique (Pro- 








c^d^s Paul 








Girod) 




3739/10 


15 Feb., 1910 


Johannes Harden 


Improvements in or relating to 








metallurgical processes. 


7303/10 


23 March, 1910 


Johannes Harden 


Improvements relating to the 
reduction of metals from their 
oxides or other compounds. 


9459/10 


19 April, 1910 


James Henry 
Reid 


Electric induction furnaces. 


9897/10 


23 April, 1910 


Johannes Harden 


Improvements relating to electric 
furnaces. 


12214/10 


22 May, 1909 


Albert Hiorth 


Improvement in electric induction 
smelting furnace. 


15139/10 


6 July, 1909 


Carl Hering 


Improvements in or relating to 
electric furnaces. 


19804/10 


24 Aug., 1910 


James Henry 
Reid 


Electric furnaces. 


19805/10 


24 Aug., 1910 


James Henry 


Means for regulating electrodes in 






Reid 


electric furnaces. 


21206/10 


12 Sept., 1910 


Johannes Harden 


Improvements in and relating to 






and Electric 


the production of metals from 






Furnaces and 


their ores by reduction. 






Smelters, Ltd. 




1609/11 


21Jan.,1911 


James Henry 
Reid 


Improvements in electric furnaces. 


8901/11 


10 April, 1911 


Ernesto Stassano 


Electric furnace. 



APPENDIX 



201 



A. List of English Patents prepared by John E. Eaworth, Chartered 
Patent Agent, Queen Anne's Chambers, 28, Broadway, 
London, S.W. — continued. 



No. of 
Patent. 


Date of Patent. 


Patent Qranted in 
Name or Names of 


Subject-matter of Patent. 


10231/11 


13 Dec, 1910 


Bochling'scbe 
Eisen- und 
Stablwerke 
G.m.b.H. and 
Wilhelm Ro- 
denhauser 


Improvements relating to electric 
furnaces. 


13731/11 


9 June, 1910 


Soci^t^ Anonyme 
Electro-Mdtal- 
lurgique (Pro- 
c6d68 Paul 


Method of supplying electric 
furnaces with tri-phase currents. 


14239/11 


15 June, 1910 


Girod) 
Soci^t^ Anonyme 
Electro-M^tal- 
lurgique (Pro- 
c^d^s Paul 


Improvements in the process of 
refining steel. 

1 


15824/11 


7 July, 1911 


Girod) 
Johannes Harden 
and Electric 
Furnaces and 
Smelters, Ltd. 


Improvements in or relating to 
the production of metjils from 
their ores. 



B. List of more important Heroidt Patents, relating to Electric 
Steel, prepared by La Societe Electro-MetaUurgique Frangaise, 
June, 1912. 



British. 


United States. 


Canada.' 


No. 


Date. 


No. 


Date. 


No. 


Date. 


16293 


1900 


707776 


1902 


78160 


1902 


14486 


1901 


721703 


1903 


79716 


1903 


14643 


1901 


807026 


1905 


96379 


1905 


6950 


1903 


807027 


1905 


96380 


1905 


7027 


1903 






99756 


1906 


25948 


1904 






106295 


1907 


3004 


1906 










13189 


1906 











202 



APPENDIX 



C. List of English Patents relating to the Girod Electric Steel 

Refining Furnace. 



No. 


Date. 


Name of Specification. 


13690 


4 July, 1904 . 


Improvements in electric furnaces. 


14333 


11 July, 1905 . 


Improvements in electric furnaces. 


23402 


24 December, 1904 . 


Improvements in electric furnaces. 


25174 


5 January, 1905 


Improvements in electric furnaces. 


3276 


7 February, 1907 . 


Improvements in the crowns and 
covers of electric furnaces. 


26588 


6 May, 1909 . 


Improvements in the process of 
refining steel. 


3421 


26 August, 1909 


Method of supplying electric furnaces 
with tri-phase currents. 


27003 


20 November, 1909 . 


Addition to No. 26588 of May 16th, 






1909. 


13731 


9 June, 1910 . 


Method of supplying electric furnaces 
with tri-phase currents. 



D. List of Patents relating to the Kjellin type of Induction 
Furnace and its later modifications , prepared by the Grondal 
Kjellin Company, of London, September, 1912. 





British Nos., 


United States 


Canadian Nos., 


Subject-matter of 
Patent. 


Patentee. 


with date of 


Nos., with 


with date of 




application. 


date of grant. 


grant. 


Benedicks 


18921 


682088 


73701 


Coil inside melt- 


Kjellin. 


Oct. 23, 1900 


Sept. 3, 1901 


Nov. 12, 1901 


ing chamber. 


Kjellin . 


142U 


800857 


None 


Jacketed coils for 




July 11, 1904 


Oct. 3, 1905 




cooling. 


>» • 


None 


None 


100269 
July 21, 1906 


Conductors ar- 
ranged to op- 
pose leakfield. 


»» 


None 


None 


102575 
Dec. 11, 1906 


Channels for re- 
sistance heat- 
ing. 


»» 


None 


None 


104207 
Mar. 19, 1907 


Resistance heat- 
ing furnace. 


Colby . 


None 


428378 


None 


Annular conduct- 






May 20, 1890 




ing crucible. 


j» 


None 


428379 
May 20, 1890 


None 


Annular conduct- 
ing crucible. 


»» 


None 


830208 
Sept. 4, 1906 


None 


Crucible lining. 


» • • 


None 


840825 
Jan. 8, 1907 


None 


Crucible with re- 
cess in under- 
side. 



APPENDIX 



203 



D. List of Patents relating to the Kjellin type oj Induction 
Furnace and its later modifications, prepared by the Grondal 
Kjellin Company, of London, September, 1912 — continued. 





British Nos., 


United States 


Canadian Nos., 


Subject-matter of 
Patent. 


Patentee. 


with date of 


Nos., with 


with date of 




application. 


date of grant. 


grant. 


Colby » 


None 


840826 


None 


Arc shaped cruci- 






Jan. 8, 1907 


4 


ble. 


»» •. • 


None 


859641 


109540 


Coils round cruci- 






July 9, 1907 


Jan. 7, 1908 


ble. 


Hay 


27972 


932469 


125527 


Heat radiating de- 




June 19, 1909 


Aug: 3i; 1909 


May 10, 19L0 


vice for induc- 




- 


■...*_ 


' 


tion furnace. 


Rochling^ 


None 


877739 


103614 


Liquid slag ob- 


Roden- 




Jan. 28, 1908 


Feb. 12, 1907 


tained by con- 


hauser. 


/ 


' , 




centration of 






...'.' 




current by 


- 




— - , 




means of hearth 




• 


. ' : ■ 




projections. 


Rochling- 


12329 


939095 - • 


103615 


Heating by 


Roden- 


May 26, 1906 


Nov. 2,1909 


Feb. 12, 1907 


means of in- 


hauser. 








duced currents 
and currents 


' 








introduced 


■ 








through ter- 
minal plates. 


Rochling- 


18513 


987404 


116021 


Wide central 


Roden- 


Feb. 26, 1908 


Mar. 21, 1911 


Jan. 12, 1909 


hearth obtained 


hauser. 




* • 


•1 


by cores with 








' 


section long in 


- 


, 






proportion lo 
width. 


Rochling- 


18523 


984970 


None 


Lower portions 


Schmelzer. 


Nov. 4, 1907 


Feb. 21, 1911 




of charge in any 
furnace heated 
by means of an 
auxiliary source 
of heat coiisist- 
ing in the pas- 
sage of current 
through elec- 










trodes in hearth. 


Rochling- 


27556 


411945 


126698 


Process for the 


Shouawa 


Dec. 13, 1907 


(AppL) .- 
Jan. 28, 1909 


July 5, 1910 


preliniinary re- 
fining of pig- 




* 


(recorded) 




iron in a mixer 






- 




provided with 
electric heating 
device. 


Rochling- 


11917 


— 


126855 


Electrodes of 


Sbonawa- 


May 22, 1907 




July 12, 1910 


metal plate 


Rodenhauser 


, 


•' • 




.coated with 
such material 
as dolomite or 






- 




' magnesite, etc. 



^04 



APPENDIX 



D. List of Patents relating to the Kjellin type of Induction 
Furmice and its later modifications^ prepared by the Grondal 
Kjellin Company, of London, September, 1912 — continued. 





British Nos., 


United States 


Canadian Nos., 


Subject-matter of 

Pfttftnt 


Patentee. 


with date of 


Nos., with 


^vith date of 




application. 


date of grant 


grant. 


X (wWUV* 


Harden 


3739 
Feb. 15, 1910 


None 


None 


Gas- fired furnace 
with terminal 
plates.' 


>j • 


None 


861031 
July 28, 1907 


None 


. 


» • 


16269 


None 


103815 


Furnace trans- 




July 18, 1906 




Feb. 26, 1907 


former with 
hollow conduc- 
tors. 


?> 


8445 


897203 


112412 


Detachable hearth 




Apr. 11, 1907 


Aug. 25, 1908 


June 16, 1908 


lining. 


» 


26251 


967908 


None 


Charge heated by 




Nov. 12, 1909 


Aug. 23, 1910 




arcs, and by 
passage of cur- 
rent through 
terminal plates 
having suitably 
graded resist- 
ance. 


»» 


26266 


967909 


None 


Composite termi- 




Nov. 12, 1909 


Aug. 23, 1910 




nal plate. 


»» • 


8194 


977303 


None 


Conducting cru- 




Apr. 5, 1909 


Nov. 29, 1910 


- 


cible. 


Frick 


4866 


917040 


87552 


Flat coils above 




Feb. 27, 1904 


Apr. 6, 1909 


May 31, 1904 


or below cruci- 
ble. 


»> • 


29271 


932013 


121300 


Two or more coils 




Dec. 22, 1906 


Aug. 24, 1909 


Oct. 19, 1909 


around bath. 


jj • • 


22519 


933169 


104156 


Suppression o f 




Dec. 18, 1905 


Sept 7, 1909 


Mar. 19, 1907 


leakfield. 



III. Abstracts of the Eablibb Patents relating to Electric 
Furnaces for Iron and Steel Production. Collected 
AND Arranged by John B. G. Kershaw. 

1879, No. 2110. Granted to Charles William Siemens, of 
London, for ** Improved Means and Apparatus for Producing 
Light and Heat by Electricity.** 

(An Extract from this Patent is printed on p. 12). 

1887, No. 700. Granted to Sebastian Ziani de Ferranti, of 
London, for ** Improvements in Electric Furnaces and Apparatus 



APPENDIX 205 

fm* Seating^ Lighting^ and carrying on Chemical Processes ; and 
in the Working of such Furnaces or Apparatus.'' 

I, Sebastian Ziani de Ferranti, of 5, Stanwick Road, West Kensing- 
ton, in the County of Middlesex, Electrician, do hereby declare the 
nature of this invention and in what manner the same is to be per- 
formed to be particularly described and ascertained in and by the 
following statement : — 

According to this invention I form an electric furnace in such a 
manner that the current which circulates in the crucible or container of 
the furnace is not conducted there from the outside but has local 
currents induced in it by a varying or alternating magnetic field or it 
might be by a rotating or moving field. In this way an electric furnace 
is obtained without electrodes in the crucible thereby avoiding all 
action of electrodes upon any metal or ore tliat is being melted or 
reduced therein. 

One way in which the furnace may conveniently be formed is to 
make the crucible of an oblong annular shape placed horizontally and 
with magnet core pieces rising up through the open space in the centre 
and outside each of the two longer flattened sides and with an insulated 
conductor wound between the pole pieces below tlie crucible. Prefer- 
ably I insulate the conductor with fire clay or asbestos or slag. 

The central and outer pole pieces are connected at the bottom so as 
to form two horse-shoe magnets one embracing one of the longer sides 
of the crucible and the other the other side of the crucible. Connecting 
pieces are also placed over the tops of the pole pieces but these are 
removeable so that the crucible may be readily got at and charged with 
material. 

The crucible forms a continuous trough open at the top and a suit- 
able lid is provided by which it can be covered over when the furnace 
is in operation. The whole furnace may be mounted on trunnions 
projecting from the centre of its longer sides — so that it may be tilted 
and the contents of the crucible when liquid poured out from one of its 
ends. 

When the furnace is to be used for melting metal or reducing ores 
I form the crucible or container or refractory material, and if necessary 
line it with a lining of any refractory substance. 

When a metallic ore is to be reduced in the crucible a strip of wire 
or blanks or pieces cut from thin sheets of the metal contained in the 
ore or with which the metal in the ore is to be alloyed may be placed 
around the interior to give conductivity at starting or a granulated con- 
ductor or a flexible carbon stick or carbonized paper may be placed 
around the interior of the crucible to effect the same object. 



206 APPENDIX 

When carbon is required to be used in the reduction of the ore thin 
layers of carbon may, be alternated with thin layers of ore — or a gas or 
vapour rich in carbon might be supplied to the crucible as the process 
of reduction is being carried on. For some metallic processes a 
vacuum may when required be formed in the crucible to extract gases. 

When several furnaces are used they may be placed in parallel on 
the circuit of the exciting machine the current may also be fed to each 
furnace through what are known as distributors. 

Induction resistances may also be used to regulate the working of the 
several furnaces. 

If the furnace is to be used for boiling or heating liquids a pot of 
brass or copper may be substituted for the refractory crucible. 

In this way the furnace may be used for boiling water or for heating 
generally either for cooking or for other purposes as for example for 
heating water in a pipe or vessel forming part of a circulating hot 
water heating apparatus. The furnace can also be used for effecting 
the decomposition of liquids contained in a pot or vessel of insulating 
material or the precipitation of metal from them in cases where it is 
undesirable to act upon the liquids by electric currents passing through 
electrodes. 

When the furnace is to be used for obtaining light a ^hallow 
crucible left open at the top may be used and powdered charcoal be 
supplied to it or a metal such as platinum or iridium — the crucible 
used may in this latter case be conveniently formed of lime. 

Having now particularly described and ascertained the nature of 
my said invention and in what manner the same is to be performed, I 
declare that what I claim is : — 

1. An electric furnace or apparatus in which metal or ma,terial 
whilst contained in a suitable crucible or vessel is heated or melted by 
currents induced directly in it. 

2. An electric furnace or apparatus composed of a crucible or con- 
taining vessel heated by induced currents circulating in it or in the 
material contained in it without such currents being conducted there 
from the outside. 

3. An electric furnace or apparatus composed of an annular crucible 
or vessel of refractory material in a varying or alternating magnetic 
field or in a rotating or moving field. 

4. An electric furnace or apparatus composed of an annular crucible 
or vessel of conducting metal or material in a varying or altematin 
magnetic field or in a rotating or moving field. 

5. The construction of electric furnaces or apparatus substantially 
in the manner herein before described and illustrated in the drawings 
annexed. 



g 



APPENDIX 207 

1898, No,. 11604. Granted to Ernesto Stassano, of Borne, for 
" Improvements in and connected tvith the Electro-metallurgical 
Production of Iron, Steel, and their Alloys with Chromium, 
Tungsten, Nickel, Manganese, and the likeJ^ 

I, Ernesto Stassano, of Via Porta Salaria, No. 7, Rome, Italy, Captain 
of ArtiUery in the Italian Army, do hereby declare the nature of this 
invention and in what manner the same is to be performed, to be parti- 
cularly described and ascertained in and by the following statement : — 

This invention relates to improvements in and connected with the 
electro metalltirgic production of iron, steel and their alloys with 
chromium, tungsten, nickel, manganese and the like and consists in the 
utilisation of the heat radiating from the voltaic arc for primary deter- 
mining the reduction of the oxide of iron and other metals, so as to 
enable the carbon, added to the mineral, to effect the reduction of the 
oxide, absorbing the oxygen of iron and changing itself in volatile 
carbonic oxide, the mass afterwards accumulating at the bottom of the 
furnace from wience it is run into moulds for ultimate industrial use. 

For this purpose the ore, prepared as hereinafter described, is intro- 
duced into an electric furnace and subjected to the heat which radiates 
from the voltaic arc produced at the bottom of llie furnace. 

The said furnace consists of a chamber having the form of. a 
vertical double cone the large bases of which abut against each other. 
The smaller inverted cone of the said chamber abuts against another 
slightly conical chamber which forms a pot. 

At the joint of the said pot and smaller lower cone are employed 
two carbons which form the poles for the electric current between 
which the arc is formed. 

The distance between the said carbons may be altered at will in any 
suitable manner. 

The pot is formed with a hole through which the metallic fluid is 
run out. The top of the furnace is closed by a hopper having at its 
lower end a valve operated by a puU lever which permits of placing the 
ore into the furnace without permitting air to enter the same. Near the 
top two holes are formed in the furnace, furnished with tubes which 
serve for the escape of the products of reaction and which are connected 
with a hydraulic valve, adapted to prevent the entrance of air when the 
internal pressure of the gases is below that of the atmosphere. 

The ore is prepared as follows : — 

First of all the ore whatever it may be (oxide or carbonate) is care- 
fully selected by hand and then reduced and pulverised by any weU 
known means. 

After having sifted and washed the powder to the required extent 



208 APPENDIX 

and dried, when its nature allows it, it is magnetically refined for the 
purpose of separating the gangue which may remain mixed therewith, 
Le, it is well known that oxide or iron such as FeO, Fe^O^, is attracted 
by the magnet and in this invention the mineral is thus, in a pulverised 
state, passed under a magnet in order to separate it from the gangue as 
much as possible. 

The ore is then carefully analyzed for the purpose of correctly 
ascertaining its composition and to regulate the amount of carbon, lime, 
silica necessary to promote fusion. 

Calcareous products are added if the mineral is of a silicious nature 
and silica is added if the mineral is calcareous. Afterwards the sub- 
stances aforesaid which may be finely powdered, are mixed with the 
said mass ; 5 — 10 per cent, water is then added thereto and the paste 
subjected to a pressure of about 150 — 200 kilograms per square centi- 
metre. 

The cakes thus obtained when dry are reduced to pieces of about 
3 — i centimetres in size and the furnace is then charged with this 
material. 

If it is desired to produce alloys of iron, the ore is mixed and melted 
with the oxides of metal required for the production of the quality and 
kind of material desired. 

Having now particularly described and ascertained the nature of my 
said invention, and in what manner the same is to be performed, I 
declare that what I claim is : — 

1st. The utilization of caloi-ic energy of the voltaic arc for primary 
detei-mining the reduction of oxide of iron and the metals to be com- 
bined therewith and afterwards melting the metallic masses reduced, 
for the purpose of obtaining in a fluid state the product desired, 
all substantially as set forth. 

2nd. The method of preparing the ore, aU substantially as described. 

3rd. The general construction and combination of parts and method 
of closing the furnace, all substantially as set forth. 

1900, No. 18921. Granted to Gvstav Benedicks, of Stock- 
holm, for " Impt^ovements relating to Electric Furnaces. ^^ 

I, GusTAF Benedicks, of 4, Birger Jarlsgatan, Stockholm, in the 
Kingdom of Sweden, Managing Director of a Company, do hereby declare 
the nature of this invention and in what manner the same is to be per- 
formed, to be particularly described and ascertained in and by the 
following statement : — 

For smelting or heating ores metals and the like furnaces have 
already been employed, in which an electric current sufficient for the 



APPENDIX 209 

smelting of the ore or of the metals is induced in the material to be 
heated or smelted, or in a conductor in contact with said material, by 
means of alternating currents produced in a coil surrounding the 
furnace, which encloses a core of iron or of other magnetic material. 
The object of my invention is to arrange the induction coils in such 
furnaces in such a manner that they become cheaper and more 
effective. 

In order tKat my invention may be readily understood and carried 
into effect I will describe the same fully with reference to the accom- 
panying drawings in which : — 

Referring to the drawings, the furnace is seen to consist of the 
following parts : — the refractory walls of the furnace and an annular 
groove or chamber for the reception of the charge to be smelted 
or heated ; and a central channel, surrounding the iron-core. In 
furnaces of this kind as heretofore constructed, the conductor connected 
to the generator for the electric current, is coiled around the furnace, 
but according to my invention the conductor is coiled directly on the 
core and thus inside the smelting or heating chamber. 

By arranging the conductor in such a manner the advantage is 
attained that the length and thus the cost, as well as the loss of energy 
at the passage of the current, is considerably reduced. The surface of 
the wall between the induction coil and the chamber also becomes con- 
siderably smaller than in the case when the conductor is placed outside 
said chamber, in consequence whereof also the quantity of heat trans- 
mitted from the furnace to said conductor, becomes smaller. 

The larger diameter the furnace possesses, the larger is the area 
between the induction coil and the chamber (at the same thickness of 
the wall), when the coil is placed outside the furnace and the number 
of the lines of force which escape between the coil and the chamber 
also becomes larger in consequence whereof the self-induction is 
increased. By such an arrangement the effect thus is diminished as the 
diameter of the furnace increases. 

In furnaces arranged according to my invention the space between 
the induction coil and the chamber becomes independent of the diameter 
of the furnace and always smaller than when the coil is placed outside 
said furnace-chamber, in consequence whereof the effect becomes con- 
siderably greater than in the furnaces as heretofore constructed, and in 
addition my improved furnaces may also be made in considerably larger 
sizes than has been possible heretofore. 

Having now particularly described and ascertained the nature of my 
said invention and in what manner the same is to be performed, I 
declare that what I claim is : — 

An improved electric furnace for smelting or heating by means of 

E.T.M. p 



210 APPENDIX 

an electric current induced in the material to be smelted or heated or in 
a conductor being in contact with said material, in which furnace the 
induction coil is coiled inside the smelting or heating chamber around 
the central iron core, surrounded by said chamber instead of being 
coiled outside the furnace substantially as hereinbefore described and 
illustrated by the accompanying drawings. 

1900, No. 22584. Granted to Charles Albert Keller, of 
Paris, for ** Aii Electiic Furnace with Tivo Bed-Plates.*' 

The present invention has for its object an improved furnace which 
obviates the serious drawbacks caused by overheating and combustion of 
the electrode at the point where it enters the furnace roof, and which 
operates without electrodes external to the furnace. Its electrodes are 
formed of two movable sole-plates, the couplings and connections 
whereof are completely separated from the furnace hearth, the 
deteriorating action of which can consequently have no effect upon 
them. 

The furnace comprises principally two movable sole-plates of the 
same shape each of which is composed of a certain number of fixed 
carbons preferably of rectangular section, which carbons are placed 
upon a base plate of sheet iron and surrounded at their upper part 
by a hearth of refractory material. This hearth is formed of little 
arches of fire-brick supported at one side upon the metallic centre piece 
having sloping sides and on the other side upon the metallic side 
plates. The four ends of the fixed carbpns rise above the fire-brick-sole 
for a suitable distance and have the small carbons simply placed upon 
them. The electric contacts of the connecting pieces are thus com- 
pletely separated from the melting bed and are heated by conduction of 
the heat merely to the minimum temperature at which they can be kept. 
Small copper bars are suitably attached to the faces of the lower part of 
the fixed carbons by means of coupling-plates and bolts. These bars 
which are bent at right angles outside the body of the sole-plate, 
are connected to the conductors of the source of electricity. The 
coupling-plates bear the sole-plate supports fixed to the bottom of the 
sole-plates and thus connect the carbons fully to the copper bars carry- 
ing the current at the same time as the base on which they rest. The 
size of the sole-plate are free from the connecting organs of the con- 
ductors so as to render the inspection and control thereof easy gind to 
allow of the circulation of air around the conductors of the electric 
current ; this circulation can b^ rendered more active by means of a 
fan» The two sole-plates can be separated as may be requisite by means 
of the melting bed the length whereof is variable according to the 



APPENDIX 211 

electric power to be employed. This melting bed is preferably of fire- 
proof brick-work and contains only the material to be treated. Each of 
the movable sole-plates possesses a metallic bar which engages in the 
recesses formed in the masonry to prevent the faQing down of the 
current conductors and of the fused material which covers them. The 
sole-plates are connected together by a system of cables travelling upon 
sheaves and attached to a wheel upon the shaft of which is a crank and 
handle. In order to render the grip of the cable upon this organ more 
effective a drum may be used in place of the wheel shewn and the 
cable may be coiled thereon two or more times. The upper part of the 
electric furnace is formed of an arch of fire-proof material having a 
chimney for the escape of the hot gases. Openings formed in the walls 
of the furnace admit of the insertion of the sole-plates in the interior 
thereof ; the said openings may be closed or not after the introduction of 
the said plates. 

Having now particularly described and ascertained the nature of 
my said invention and in what manner the same is to be performed, I 
declare that what I claim is : 

1. An improved electric furnace in which two sole-plates are com- 
bined to form electrodes in a single furnace, each of said sole-plates 
being respectively connected to one of the terminals of the source of 
electricity, in such a manner that the electric cuiTent flowing from one 
sole-plate to the other through the material to be treated can heat the 
same to incandescence and fusion substantially as set forth. 

2. In an electric furnace of the type set forth, the arrangement upon 
the two sole-plates of movable carbons supported by the fixed carbons, 
the said movable carbons being the only replaceable electrodes and 
preferably composed of the fragments of electrodes otherwise useless in 
the industry, substantially as set forth. 

3. In an electric furnace of the type set forth, a sole-plate formed of 
a plurality of fixed carbons receiving the electric current by contact on 
their faces by means of thin copper conductors in the manner set forth 
and transmitting the same to small electrodes placed loosely upon them, 
the melting bed of this sole-plate being separated from the chamber 
containing the electric contacts by means of a floor of refractory material 
preventing the heating of the contacts by conduction and permitting 
the said contacts to be accessible and capable of refrigeration if 
requisite, substantially as set forth. 

4. In an electric furnace of the type set forth the arrangement of a 
melting bed between two mobile sole-plates in such a manner as to 
admit of the resistance of thA furnace being regulated by the moving 
towards or fi*om one another of the said mobile sole-plates and the 
avoidance if necessary of contact of the material treated with the carbons 

p2 



212 APPENDIX 

of the sole-plates ; said sole- plates having metallic contact pieces pass- 
ing through channels formed in the brick-work of the furnace bed in 
such a manner as to prevent the falling down of the conducting body 
or of the material treated, substantially as set forth. 

5. The improved electric furnace constructed as described and 
illustrated with reference to the accompanying drawings. 

1901. No, 14486. Granted to ''La Societe Electro-metal- 
lurgique Franfaise,'' of Froges, Isere, France (Owners of the 
Heroult Patents), for a " Process and Apparatus for the Manu- 
facture of Wrought IroUy Steel, and Cast Irony by Electnc 
Heating,*' 

This invention relates to an improved process for the production by 
means of an electric furnace of wrought iron, steel, and cast iron of 
very definite composition, the separation of the impurities from the 
ore or the metal with which the process starts being ensured by a 
methodical operation which also enables the exact content of carbon of 
the final product to be determined. 

For this purpose an electric furnace is employed so arranged that 
the metal produced is protected against contact with the electrodes, 
which furnace may be of known construction, but is preferably of the 
constmction hereinafter described. 

The characteristic feature of the process is that by means thereof 
there may be obtained at will from one and the same furnace and even 
during one and the same operation, various descriptions of cast iron, 
wrought iron, or steel of any degree of carburisation. 

The reduction, fining and purification of the metal are effected 
successively in the same apparatus, by means of the successive additions 
of reagents and by variations of the temperature. 

The furnace chamber is formed as a rectangular crucible into which 
project the electrodes ; it is provided with two tapping holes at 
different levels ; the lower one serves for running off the metal, and the 
upper one serves for running off the slag and other impurities. 

The furnace is closed at top as follows : — Between the electrodes, 
and on the outer sides thereof are placed arched covers composed 
of fire-bricks encased in an arched iron framing having an outer rib 
which is formed with a hole at each end, and one in the middle ; at the 
ends are angle iron abutments for the fire-brick lining. By means of 
the holes the one or the other end of either cover can be raised up, as 
shewn at Fig. 4, thus forming a charging door. The covers can also 
be entirely removed by lifting tackle by means of a hook engaging with 



APPENDIX 213 

the middle hole and a cliain. The open spaces on the sides and 
between the electrodes are closed by fire-brick slabs. 

For producing metals direct from the ore, the furnace is started in 
the ordinary way by throwing in a mixture of ore and carbon or a small 
quantity of metal ; the furnace is then fed intermittently with charges 
of ore mixed with carbonaceous matter in suitable proportions. 

The ore is preferably employed in lumps so as to form above the slag 
bath a permeable layer through which the reaction gases can rise, 
whereby these heat and partially reduce the ore and then pass away in 
a cooled condition. 

Any kind of carbonaceous fuel can be used, the quality depending 
only upon the kind of metal to be produced ; it is preferably employed 
in the form of granules. 

The quantity of fuel employed per unit of metal will vary firstly 
according to the proportion of reducible oxide in the ore ; secondly 
according to the proportion of carbon required in the metal to be pro- 
duced, and thirdly according to the more or less perfect utilisation of the 
reducing gases given off, that act upon the ore. The proportion of 
carbon employed must therefore be determined for each particular 
apparatus and for each kind of ore. 

Under the action of the electric current the ore is melted and 
reduced ; the heavier metal collects at the bottom of the furnace while 
the slag collects on top. When the slag has collected to a certain 
extent it is discharged through the upper tapping hole, either con- 
tinuously or intermittently. 

The smelting operation consists of several phases which I will 
describe successively. 

Reduction. 

According to the proportion of carbon enployed and the temperature 
attained, there may be obtained at will either wrought iron in pasty or 
liquid form, or a more or less carburated metal. 

Thus wrought iron can be manufactured directly in operating in 
the presence of an excess of oxidising slag, but this method is less 
economical than if cast iron be first produced and this be then 
refined and purified in the same apparatus. The temperature 
required for the production of cast iron is much lower than that 
necessary for producing wrought iron, so that a considerable saving 
of electrical energy will be effected and the uselessly expended heat 
in raising the slag to the high temperature is also saved. The 
temperature need only be raised to a higher degree towards the end 
of the refining and purifying operation. 



214 APPENDIX 

The process is therefore preferably carried on in the last described 
manner. 

The process may also be carried out with advantage by first 
reducing the ore and producing cast iron in a furnace which may 
either be heated electrically or otherwise, and then effecting the re- 
fining and puriBcation in the above described electric furnace. 

Refening and Purifying. 

The furnace being started and a bath of metal having been pro- 
duced in the bottom thereof, the excess of slag is discharged through 
the upper tapping hole, and there is added oxide of iron or other suit- 
able oxide which foi-ms on the bath of the ore an oxidising bath. The 
refining is effected by the reaction of the slag and the carburated metal, 
and takes place very rapidly on account of the high temperature of the 
furnace. The refining can be stopped at the desired point, or it can be 
carried further and the metal be afterwards brought back to the desired 
condition by suitable additions, in the known manner. 

The purification is effected in the same furnace, either during or 
after the refining. For dephosphorising the slag is rendered basic by 
the addition of lime ; for the production of special kinds of steel there 
are added, before tapping off, suitable substances in the known manner. 

The process can be employed for the manufacture of wrought iron 
or steel from cast iron and scrap whether the cast iron be charged in 
a molten condition from a blast furnace, cupola, and the like or whether 
it be charged in solid pieces. 

In all these operations the quality of the metal can be ascertained by 
taking samples with a ladle. 

All the above described operations are effected according to this 
invention under economical conditions at least as advantageous as by 
the ordinary metallurgical processes, and the products obtained are 
comparable in quality with the best products furnished by the Siemens 
or crucible processes. 

I am aware that Siemens melted steel in an electric crucible in the 
year 1884 ; but the processes employed heretofore comprised two kinds 
of apparatus, namely, firstly those in which the metal has not been pro- 
tected from contact with the electrodes, or where the crucible has been 
made of carbon ; in this case carburation of the metal has necessarily 
taken place and consequently products could not be obtained, such as 
result from the present invention ; secondly, the furnaces in which the 
contact of the metal with the electrodes is avoided are heated by 
radiated heat from a resistance, and by this means even a small quantity 
of material cannot be heated to a sufficiently high temperature, so that 
no practically useful result is obtained. 



APPENDIX 215 

Thirdly, none of the processes heretofore proposed have employed 
an apparatus arranged so as to discharge the slags separately and 
to effect during a single operation a series of refining and purifying 
reactions. 

Having now particularly described and ascertained the nature of my 
said invention and in what manner the same is to be performed, I 
declare that what I claim is : — 

1. The herein described process for the manufacture of all kinds of 
wrought iron, steel, and cast iron, in an electric furnace wherein the 
metal bath is protected from contact with the electrodes and the slag or 
scoria is discharged as may be required at a level above the metallic 
bath. 

2. The herein described construction of electric furnace for carrying 
out the method of operating referred to in the first claim, which furnace 
has a second tapping-hole situated above the usual one and serving for 
the discharge of the slag, scoria and other impurities floating upon the 
metallic bath. 

3. In an electric furnace such as is referred to in the second claim, 
the use of a movable cover or set of covers for enclosing the top of the 
furnace and adapted to be raised or tilted up on one side for effecting 
the charging of the furnace with the ores, pig metal, scrap and other 
materials to be treated substantially as described. 

4. The use of an electric furnace with an upper and a lower tapping 
hole for the direct production of wrought iron from iron ore, sub- 
stantially as described. 

1901, No. 14643. Granted to " La Societe Electro-metaU 
lurgique Frarifais,** of Froges, Isere, France (Owners of the 
Heroult Patents), for an " Electiic Furnace arranged for being 
Oscillated or Tipped.'^ 

This invention relates to an electric furnace that is capable of 
being oscillated or tipped over for discharging its contents, which 
allows all the operations that are performed by means of the ordinary 
electric furnace to be carried on, with the advantage that it can be 
used for other operations such as the manufacture of steel. 

The arrangement of the furnace is such that its contents can if 
desired be only partially discharged, so as to leave a certain portion 
in the same for starting a further operation with certainty and 
rapidity. 

Also, for certain purposes only a fraction of the contents of the 
furnace can be run off practically without interrupting the operation, 
which in being continued may result in a product different from the 



210 APPENDIX 

portion previously run off, so that, for example, several qualities of 
steel can be manufactured from a single charge of the furnace. 

If the furnace be provided with suitably arranged tuyeres, steel 
can be treated according to the Bessemer process, by tilting the 
furnace backwards so that the metal covers the tuyeres and then 
admitting the blast. In this case pig metal can be treated which 
need not contain either phosphorus or silicon, because in this case 
the necessary heat is not required to be furnished by the phosphorus 
or the silicon, being supplied by the electric energy either during the 
blast or during intervals when this is interrupted. For a furnace of 
the size shown with carbon electrodes measuring 30 cm. X 30 cm. a 
current of about 100 volts for the two arcs is employed, the strength 
varying from 2,000 to 5,000 amperes. 

The tilting of the furnace can be effected by any suitable means 
such as a hydraulic motor. The metal may be run from the furnace 
either into ingot moulds on trucks or into casting ladles. 

The furnace consists of a crucible closed by a cover which carries a 
small chimney and through which the two electrodes pass ; a spout is 
provided for running off the metal on tilting the furnace. 

For effecting the tilting, the bottom of the furnace is arched and 
carries two arched rails, having on one side a flange, like a railway 
wheel, and formed with cogs on the other side, which engage with 
corresponding cogs formed on straight rails fixed on the floor. A flat 
portion of the rails rests upon the flat portion of the rails at the side 
of the cogs, which only serve for guiding. 

Each electrode is carried by an arm projecting from a sliding 
upright, which can be raised or lowered by means of a rack and toothed 
gearing worked by a worm and hand wheel, the upright being guided 
by rollers in a standard which is of a trough-shaped section. These 
standards are fixed to the back of the furnace casing as shown, with 
the inter-position of insulating material. 

Each carbon electrode is surrounded by a collar or loop of sheet 
metal, copper wedges being inserted between the two, which wedges 
serve to convey the electric current to the electrode, conducting tables 
serving to supply the current to the wedges, to which they are secured 
I y bolts. A screw spindle turned by a hand wheel enables the collar 
to be tightened up or loosened, the spindle screwing through a nut fixed 
to the two ends of the collar and thereby drawing the latter and with 
it the electrode with greater or less force against a plate fixed to the 
arm. Two doors arranged in diagonal positions at each narrow end of 
the furnace serve for charging the materials as also for repairs and for 
clearing the furnace bed and the electrodes from adhering material. 

In the modification the carbon electrodes are carried by the arm 



APPENDIX 217 

fixed to the upper end of the plunger of a hydraulic cylinder whereby 
the electrodes can be more readily raised up entirely out of the furnace 
as indicated by the dotted lines. Another hydraulic cylinder, the 
plunger of which is attached to the rail, serves to tilt the furnace 
over when required. 

When the furnace is to be used for bessemerising, a wind chest is 
provided at the back of the furnace, from which tuyeres pass through 
the furnace wall in such a position as to open above the metal bath for 
ordinary working, but which are submerged in the bath when the 
furnace is tilted backwards, so tliat on them sending a blast through 
them the required bessemerising is carried out. 

If the spout of the furnace be formed as a ladle at its end and be 
provided with a discharge hole and plug, the furnace may be used 
directly for casting purposes, on being tilted forward, and as the metal 
is in this case drawn from the bottom of the bath, it will be very free 
from impurities. 

The above construction of oscillating or tipping furnace may also 
be used with only a single pendant electrode, the second electrode or 
pole of the circuit being fixed to the interior of the furnace. 

Having now particularly described and ascertained the nature of 
my said invention and in what manner the same is to be performed, I 
declare that what I claim is : — 

1. An electric furnace arranged to be oscillated or tipped wherein 
all the metallurgical operations usually performed in electrical furnaces 
can be carried on and which can also serve for the manufacture of 
steel, the said furnace being constructed and operating substantially 
as herein described. 

2. In an oscillating furnace such as is referred to in the first claim, 
the arrangement of the carbon electrodes within collars or loops which 
hold them on the supporting arm, the current being conveyed to the 
electrodes by means of copper wedges pressed against them by the 
collars which wedges are connected to the electric circuit, substantially 
as described. 

3. In an oscillating furnace, such as is referred to in the first claim, 
the provision of tuyeres connected to a blast supply for carrying out 
the same operations as in a Bessemer converter, in em^Dloying pig 
metal, which need not contain either phosphorus or silicon, substantially 
as described. 

4. In an oscillating furnace such as is referred to in the first claim, 
mounting the carbon electrodes upon the plungers of hydraulic 
cylinders adapted to raise them entirely out of the furnace when this 
is to be tipped, substantially as described. 

5. The combination with an oscillating furnace such as is referred 



218 APPENDIX 

to in the first claim, of hydraulic cylinders for effecting the tipping 
thereof, substantially as described. 

1901, No. 24234. Granted to Charles Albert Keller, of Paris, 
for " Improvements in the Obtainment of Metals and Alloys and 
in Furnaces to be Employed Therein. ^^ 

Having now particularly described and ascertained the nature of 
this invention and in what manner the same is performed I declare that 
what I claim is : — 

1. An electric furnace arranged or constructed substantially as 
hereinbefore described and illustrated by the accompanying drawings. 

2. In electric furnaces two groups of electrodes, the electrodes of 
each group being in parallel, while the two groups of electrodes work 
in series, the number of electric foci thus formed being equal to the 
number of electrodes and the arrangement of the foci being such that 
the substances being treated act as intermediate conductors between 
the two groups of conductors, the said substances being charged between 
the electrodes all substantially as hereinbefore described. 

3. In electric furnaces the arrangement of the electrodes at the 
angles, or sides, of a figure, circumscribing the section of the charging 
column, so as to leave between the foci of the electrodes a space into 
which the substances to be treated are introduced, these substances 
being thus capable of being supplied and subjected to the action of the 
foci without the proportion of the said substances being altered by the 
carburation caused by the electrodes and therefore so that the 
verifying of these components after a trial-tapping of the furnace is 
reliable, substantially as hereinbefore described. 

4. In electric furnaces, a passage around the wall of the column 
containing the substances to be treated, a communicating passage over 
the roof of the furnace proper and communications such that the reaction 
gases from the furnaces pass through these passages and are heated 
therein substantially as hereinbefore described and illustrated by the 
accompanying drawings. 

5. In electric furnaces a chamber at the bottom of the furnace and 
means for introducing the reaction gases and air thereto for effecting 
the combustion of the reaction gases and assisting in the heating of the 
said furnace and thereby increasing the thermic efficiency of the 
apparatus; substantially as hereinbefore described and illustrated in 
the accompanying drawings. 

6. In electric furnaces the hereinbefore described arrangement and 
mode of working permitting when tapping-off the molten metal, of 
causing said metal to be acted upon by long electric arcs having a 



APPENDIX 219 

powerful stirring effect and a high calorific action, so as to obtain 
simultaneously, a reheating of the molten mass, volatilization of the 
impurities, and elimination of the carbon substantially as hereinbefore 
described. 

7. In electric furnaces, the combination of two electric furnaces one 
at a higher level than the other, for the treatment of ores and metals, 
metals or alloys ; the upper furnace serving to produce the metal, or 
alloy, and the lower furnace serving for its refining, or further treatment, 
substantially as hereinbefore explained. 

1902, No. 3912. Granted to Paul Louis Toussaint Heroulty 

of La Praz, France, for " Improvements in Electric Furnaces.^' 

Having now particularly described and ascertained the nature of my 
said invention and in what manner the same is to be performed, I 
declare that what I claim is : — 

1. An electric furnace comprising a well of refractory material in 
which is effected reduction of the ore fed into the furnace at a high 
temperature, the furnace having at the bottom a carbon crucible, and at 
the top a carbon block, the electric current being conducted to the 
crucible and to the block above, so as to pass through the coke or other 
fuel which fills the well of the furnace below the upper block and is 
being constantly fed through a passage above, substantially as described. 

2. In combination with an electric furnace such as is above 
described, an adjacent preparatory furnace into which pass the hot 
gases produced by the reduction, which gases heat the ore, which in 
this hot condition is then fed into the mass of fuel in the weU of the 
electric furnace, substantially as described. 

3. The block of carbon at the lower end of the inclined floor of the 
preparatory furnace, arranged to produce a short circuit between itself 
and the carbon block which forms the upper side of the mouth of the 
preparatory furnace, substantially as and for the purpose set forth. 

4. The modification in which the passage through which the coke 
is fed opens through the centre of a broad carbon plate to which is 
connected one of the conductors, and which forms the top of the weU of 
the electric furnace, the other conductor being connected to the carbon 
crucible, substantially as described. 

1902, No. 15271. Granted to Charles Albert Keller, of Paris, 
for " New or Improved Process for the Electric Heating of 
Metals and Other Substances.'' 

I, Charles Albert Keller of 3, Rue Vignon, Paris, in the Republic 
of France, engineer, do hereby declare the nature of my invention and in 



220 APPENDIX 

what manner the same is to be performed, to be particularly described 
and ascertained in and by the following statement : — 

The object of the present application is an electric process for heat- 
ing and refining metals and other substances, particularly iron, cast-iron 
and steel, by allowing of various metallurgic operations, for instance. 

1. The introduction into one chamber or space of one or several 
tappings coming from one or several smelting apparatus and there 
maintaining them at a temperature produced by electric current. 

2. The refining of the material, or the mixing thereof with other 
materials at any moment. 

3. The melting and the mixture of metallic waste particularly of 
iron and steel. 

4. Refining of the metal in an auxiliary chamber of the cupola itself 
after melting. 

The process is based on the employment of an auxiliary chamber 
generally of a casting ladle, the contents of which can be easily and 
rapidly inserted in an electric circuit or be subjected to the action of 
the latter. 

The casting ladle rests by means of pivots or trunnions on one end 
of a beam, the other end of which carries a counter weight intended for 
balancing the ladle and its charge ; this beam is carried by a truck, 
which can be moved on rails. This arrangement allows of bringing the 
ladle to the proximity of a smelting furnace to receive the successive 
tappings or to the proximity of each of the furnaces of a battery to 
receive from them the successive tappings ; it also permits of bringing the 
ladle under an apparatus comprising vertical electrodes supported by 
chain tackle so as to raise or lower them into the ladle for the require- 
ments of the operation as hereinafter described. 

The cupola is provided with a basin to receive the casting and 
above which is arranged a group of vertically movable electrodes similar 
to those previously described. 

The ladle is provided with a refractory jacket and does not form 
part of the electric circuit; the current enters and leaves through 
vertical electrodes arranged above it, these electrodes can be regulated 
and each set belongs to a distinct furnace, and in practice I employ 
more than one electrode for each pole, this permits of always being able 
to replace an electrode at work without interrupting or disturbing the 
course of the operation. 

If only two electrodes were provided, the removal of one of these 
would cause the breakage of the circuit. On the other hand if etich 
pole carries a minimum of two electrodes it will be possible to remove 
one of them and this would only result in an increase of tension in the 
remaining electrodes. 



APPENDIX 221 

As an example the manufacture of iron or of steel will be 
described. 

The metal contained in the ladle can be easily put into the electric 
circuit through the suitable lowering of the electrode into the bath. 
The ladle is carried on a truck adapted to be moved so as to be brought 
successively under the tapping orifices of furnaces of the same battery. 
This arrangement will be particularly useful if used with a group of 
electric furnaces since the individual output of this kind of furnace is 
less than that of blast furnaces of the ordinary kind. 

After each tapping, or set of tappings, the cast substance in the 
ladle is introduced into the electric circuit and the re-heating is effected 
by a current of suitable strength, regulatable as required. By these 
means the metal is maintained at the required temperature : the quantity 
of heat necessary for this purpose will simply replace the quantity lost 
by radiation. 

The slag which will have probably been tapped with the metal from 
the furnaces is removed in convenient quantities from the ladle so as 
not to be supei*fluously re-heated. This removal is effected by simply 
tilting the ladle. 

The electric current is interrupted when the ladle has again to be 
placed under the openings of the smelting furnace or furnaces, to receive 
a further tapping or tappings and the re-heating if required then takes 
place as described above. 

By this process a new method of working is realized ; very large 
castings can be made with furnaces the actual capacity of which is 
much less than the weight or size of the castings. The temperature of the 
melted metal can be easily regulated and the metal remaining in the ladle 
after tapping will not be wasted as often happens, as it can be kept 
hot imtil mixed with other tappings ; the founder can therefore estimate 
the amount of metal required for the filling up of large moulds without 
fear of waste resulting from too high an estimate which leads him some- 
times to under estimate and to spoil castings through insufficiency of 
metal in the ladle. 

To refine or mix the metal collected in the ladle, it is introduced 
into the electric circuit, and the removal of slag proceeded with if 
required, as already described ; the current is then regulated so as to 
considerably re-heat the metal to be refined and the necessary additions 
are then made to obtain the required quality. For example, steel can 
be manufactured with the tappings of ordinary cupolas by refining this 
tapping by the addition of oxide and as with the Martin furnace, 
desulphuration dephosphoration and deoxidation can be adopted. 

This process therefore permits of transforming an ordinary foundry 
into a steel foundry. 



222 APPENDIX 

This process of refining or mixing can also be employed for the 
metal coming from ordinary furnaces as well as from electrical furnaces. 

The process can also be easily applied to the melting and mixture of 
steel and iron waste which it may be required to re-cast, owing to the 
extreme faciUty it offers of taking samples, by the continuous access it 
permits to the metal in the ladle. For this purpose a certain quantity 
of metal (iron, steel or cast-iron) is first introduced into the ladle and a 
certain quantity of mineral which covers over the metal. The electric 
current is then passed into the ladle and the operation having thus 
commenced, pieces of metal to be re-cast and mixed are introduced into 
the liquid layer. 

These pieces of metal could not be placed in circuit in the empty 
ladle on account of their weak electrical resistance or an electric current 
of a strength inadmissible in practice would have to be used and which 
would cause large fluctuations in the operation. 

With this process which utilizes the usual strengths of current 
employed in electric melting, the operation is rendered normal and 
effective by throwing the respective pieces of metal to be cast into the 
metal bath formed in the ladle as described. 

Under these conditions, the electric working of the apparatus is in 
no way disturbed when the melting is complete ; the additions can be 
made and the operation is effected according to the usual method of 
mixing and refining of metals. In the case of iron the second melting 
effected as described corresponds to the actual manufacture in the crucible. 

The process above described also permits of transforming the 
ordinary second melting cupolas into mixed furnaces for obtaining cast 
iron or steel. As known, some cupolas have a front basin into which 
the meltings arrive ; it is this basin which will replace the ladle, which 
permits of manufacturing steel with existing apparatus for the manu- 
facture of cast-iron. 

In this form of application above the existing or specially constructed 
basin or auxiliary chamber the group of vertical electrodes are aiTanged 
so as to descend into it, after receiving the tapping and the refining is 
effected as previously described, after removal of slag. During tapping 
the electrodes can be removed or not and the process is otherwise 
proceeded with as usual. It is evident that for the refining operations 
in the case of ladles as well as in cupolas acid resisting linings are 
employed. 

Having now particularly described and ascertained the nature of my 
said invention and in what manner the same is to be performed I 
declare that what I claim is : 

1. A process for the electric melting or refining of metals and other 
substances, consisting in the employment with electric or other smelting 



APPENDIX 223 

furnaces, of an auxiliary fixed or movable feed chamber into which a 
group of vertical electrodes is adapted to be plunged, the said electrodes 
being allowed to descend into the melted material coming from the 
furnace or furnaces, in order to cause the electric current to pass through 
the said material, for maintaining the latter at the temperature necessary 
for performing in said auxiliary chamber the operation of mixing, or 
refining or for subsequent casting. 

2. In the process as described in Claim 1, the employment of a 
tapping ladle mounted on a movable truck, and adapted to be conducted 
close to a furnace or to each furnace of a battery, to receive the succes- 
sive tappings of said furnace or furnaces, and to be passed under a 
group of vertical electrodes which are plunged into the fused material 
in order to place the latter in the electric circuit and maintain it at the 
required temperature for subsequent casting into moulds, permitting of 
accumulating in the ladle a much larger quantity of melted material 
than could be obtained for immediate casting and thus making large 
castings with a small quantity of material from each. 

3. In the process as described in Claim 1, the arrangement above 
the front basin of a cupola, of vertically movable vertical electrodes, 
adapted to descend into the fused material coming from the cupola so 
as to place it into the electric circuit and maintain it at the temperature 
required for refining the casting and its direct transformation into steel 
on coming out of the cupola. 

4. In the process as described in Claim 1, the second melting and 
the refining of waste iron or steel consisting in introducing the waste 
material into a preliminary bath of suitable composition contained in a 
ladle provided with movable electrodes to permit of melting with 
currents of the usual strength, without sudden fluctuations. 

5. In the process as described in Claim 1, a method of electrical 
heating, consisting in the arrangement above the auxiliary chamber or 
appliance receiving the fused material to be treated, of a group or 
groups of vertical electrodes each group comprising two or more positive 
and negative electrodes respectively and each group belonging to a 
separate regulatable furnace, for the purpose of replacing an electrode 
at wiU without stopping the operation. 

IV. Abstracts of Papers and Notes on Electric Steel 

Eefining. 

A. The Function of the Slag in Electric Steel Refining. 

An exceedingly interesting and valuable paper upon this 
subject was presented by Eichard Amberg to the Eighth Inter- 



224 APPENDIX 

national Congress of Applied Chemistry, held in New York in 
September, 1912 (see Transactions. Sections 3 and 10, also 
MetalL and Chem. Engineering, September 12, 1912). 

From the report of this paper, and of the discussion upon it, 
which appeared in the Journal named above, the following 
extracts have been taken : — 

The function of the slag depends upon the work which the furnace 
is required to perform. In localities where power is cheap, the electric 
furnace may be used for carrying out reactions which, in other places, 
with more expensive power, would be carried out more cheaply in an 
oxidizing furnace like the open-hearth. 

Where cheap power is available, electric steel melting begins wdth 
the widely-known open-hearth process, of melting pig and scrap. 
Assuming a basic-lined bottom and hearth, heated by one or more 
electric arcs, the charge melts down, slag is formed by lime, silica, and 
iron-oxide in the form of ore or scale, — and the refining by oxidation 
takes place in the form of heterogeneous reactions of different kinds. 
After the ferric oxide dissolved in the slag has been reduced to the 
ferrous oxide, it partly acts directly on those parts of the metallic 
solution which come in immediate contact with it, and partly dissolves in 
the metal, according to the temperatures and coefficient of division of 
FeO between the two liquid phases (metal and slag). If the slag is 
saturated with FeO, the latter can assume its full concentration in the 
metal bath, according to the solubility curve. Its action there on 
manganese and the metalloids is much the same as in the open-hearth. 
It can be more energetic, however, if the operator avails himself of the 
facility of a higher temperature and of a higher concentration of FeO 
which is a special feature of the electric furnace. 

There is one essential difference from the reactions of an open-hearth 
slag. In a well-built electric furnace, practically all the oxygen 
required has to be supplied in sohd oxide form, while the open-hearth 
furnace has an unhmited supply of oxygen in the air supply. At this 
period of oxidation, the basic slags of an arc furnace, and of an induc- 
tion furnace, show a material difference. The dephosphorisation, being 
a process which reaches its maximum velocity at a temperature some- 
what below the melting point of soft iron, is accomplished more 
quickly with the comparatively colder slag of the induction furnace, 
than under the higher heat of the arc. The technical significance of 
this fact, however, is small. This dephosphorisation period may be 
carried out in an ordinary non-electric furnace. When it is finished, 
there begins an entirely new operation — the deoxidation of the metal. 



APPENDIX 225 

This involves a slag process, which none of the other furnaces can 
perform. Carbon is the chief deoxidising agent, and is bound to act 
in both phases. 

Electric heating, as described in the patents of Humbert, offers the 
possibility of heating the slag, with the addition of carbon, in a 
reducing atmosphere so quickly that it forms a high endothermic com- 
pound of calcium and phosphorus (probably CagPa) which is not 
absorbed by the steel phase ; hence the opportunity to dephosphorise 
without skimming the slag. How sensitive this reaction is, with 
regard to temperature, is shown by the fact, that without very 
accurate control of the temperature, a rephosphorisation of the metal 
has been found. Since in the reducing atmosphere, when carried on 
far enough, the partial pressure of oxygen is very low, the oxygen can 
be removed t/O a considerable extent from both phases without disturb- 
ing the equilibrium at the contact surface, while the opposite would 
be the case with an open-hearth furnace. In fact the amount of FeO 
present in the final slag is easily brought down in everyday practice to 
between 1 per cent, and 0*5 percent., and with a little attention consider- 
ably lower. The reaction, by which this is performed, is a true hetero- 
geneous one (that is, a reaction between the metal and the slag at the 
points of contact), and consequently does not come to an equilibrium 
in the original phase. FeO, as a base of the silicates, or as dissolved 
in the slag, is freed from oxygen, and the metal joins the other phase. 
Manganese is practically removed from the slag in a similar way. 
Even silica is partly reduced, when the basicity of the slag and the 
temperature are both high enough. 

The desulphurisation pi^oeess has been the subject of many experi- 
ments and discussions. In the oxidising period, where sulphur is 
being removed only to a small extent in the open-hearth, the electric 
furnace is much more efficient, especially when manganese ore is used. 
It is likely that a large portion of the sulphur forms SOa and disappears 
with the gases. As the partial pressure of and SO2, in the atmo- 
sphere of the electric furnace, is smaller than in the open-hearth, the 
reaction takes place more easily. In the reducing period a new 
desulphurising action takes place, according to Dr. Amberg, as 
follows : — 

(1) FeS + CaO -h C = Fe -(- CaS + CO at the high temperatures 
of the arc furnace. 

(2) 2CaO -f- 3FeS + CaCa = 3Fe + 3CaS + 2C0 at still higher 
temperatures, where calcium-carbide can be formed. 

(3) 2FeS + 2CaO + Si = 2Fe + 2CaS -f- SiOa at the lower slag 
temperatures of the induction furnace. 

(4) CaS -f- FeO = FeS + CaO. This equation occurs from left to 

E.T.M. O 



226 APPENDIX 

right for comparatively small amounts of oxygen, while from right to 
left it is the underlying principle of the three reactions, 1 to 3. 

In all the foregoing reactions, one feature deserves the most 
important consideration, that is, the high basicity of the slag. This 
is made possible by the high temperature attainable, especially in the 
arc furnaces. The elements which in the present electric furnace 
practice act as reducing agents for the oxides are chiefly carbon in the 
arc furnace, and silicon in the induction furnace. The manganese is 
practically eliminated altogether. The FeO is easily removed down 
to 0*5 per cent. Nickel is reduced with great ease, chromium, tungsten, 
and vanadium (according to their inherent amount of free energy) with 
a larger consumption of power. 

To explain the mecbanism of the reactions, it is best to consider 
them as reactions in a system of different phases, two liquid — metal 
and slag — the third gaseous — and the fourth (the hearth of the 
furnace) solid. It is of great importance for the advancement of 
general metallurgical knowledge, to determine the melting points of 
the pure compounds, and to give the complete diagram of the 
melting point of their mutual solutions over as wide a range of con- 
centration as possible. Much remains to be done in this field. Some 
important melting points are as foUows : FeSOs, 1050° C. ; MnSiOs, 
1150° C. ; CaSiOa, 1220° to 1225° C. ; MgSi04, 1400° C. 

The carbon thrown into the furnace and the carbon derived from the 
electrodes can j)roduce several compounds. Among these are silicon 
carbide, calcium silicide, and calcium carbide. This latter seems to be 
the most permanent under operating conditions, and is recognised by 
the liberation of acetylene from a cooled-off sample. It is only after 
this carbide has been formed that the deoxidation of the charge can be 
looked upon as completed. 

When this condition of the bath has been attained, the electric 
furnace represents the nearest approach to the ideal heterogeneous 
equilibrium, between the different phases, which has hitherto been 
accomplished in large-scale metallurgy. The converter and open- 
hearth are under the action of air and gas— the crucible metal takes 
carbon and silicon up— whereas in the electric furnace the action of 
the metal on the basic lining is almost nil, and there is no exchange of 
elements between metal and slag. However, a slight evaporation of the 
constituents of the slag does take place, and in this respect the induc- 
tion furnace, with its cold slag, has a slight advantage over the arc 
furnace. 

The author then discusses the physical aspect of the fact, that 
there is by no means an ideal two-dimensional contact surface 



APPENDIX 227 

between slag and metal, and that both phases penetrate each 
other to a considerable extent. The prevailing notion that slag 
and metal behave like oil and water is only relatively true. The 
slag swims on the metal, but where small portions of the one are 
caught in larger masses of the other, they have to overcome 
an enormous friction in order to be separated, and the smaller 
the slag particles the more difficult is their separation from the 
metal bath. It is therefore very important to keep the finished 
charge quiet, and at a sufficiently high temperature, to allow it 
to settle. Proper precautions have also to be taken afterwards 
while teaming and pouring in order that the painstaking results 
of refining may not be reversed. 

This slow physical action may furnish a new explanation for the 
slow progress of the desulphurisation, according to Equation 2. The 
microscope shows that siliceous and sulphidic products are sometimes 
contained down to two-thirds, and even lower, from the top of an ingot. 

These non-metaUic products appear as balls in the ingot structure, 
and are elongated into a cigar-like shape, after rolling or forging the 
metal. Although their melting point is lower than that of steel, they 
have not succeeded in uniting with the bulk of the slag in proper 
time. 

The author concludes with a brief discussion of the acid-lined 
electric steel furnace. An acid lining requires an acid slag, to keep 
the hearth in good condition. This acid slag wiU be much the same as 
the slag of an acid open-hearth furnace so long as the charge is treated 
with an excess of oxides, and the heat is not exaggerated. If necessary, 
it can be made to contain a higher percentage of SiOa for the same 
reasons which hold good for highly basic slags. The great difference 
from the basic electric furnace in this case is that all four phases are 
in lively reaction with each, other, and that conditions approaching a 
status of equilibrium cannot be reached ; the metal, therefore, must be 
"caught," at a certain moment of teaming. 

The solid and the metal phases react in this way, that carbon of the 
bath reduces Si from the hearth, the amount of Si present being 
regulated by a reaction between the two liquid phases, namely, by 
keeping a sufficient stock of oxides in the slag to hold the Si within the 
required limits. The slag wuU therefore be a thoroughly black one, 
particularly during the beginning of the run. Thallner ascribes a 
specific beneficent effect to this exchange of Si and to the low heat con- 
ductivity of the silica lining. Towards the finishing of the acid heat, 
the colour of the slag clears up, and its reduction finally reaches a point 

q2 



228 APPENDIX 

where the glassy masses become light grey and green coloured. 
Sulphur, as in the acid open-hearth, will remain unaltered in quantity — 
while phosphorus may be slightly decreased, by phosphoric acid being 
thrown out of solution by the stronger SiOa and then reduced to 
phosphide of iron. This has yet to be confirmed, however, and it has 
to be explained how such a reaction can take place. Nothing definite 
can be said about this reaction at the present time. 

It may bo that some of the advantages of this method are due to the 
mechanical property of the acid slag of agglomerating more easily than 
the basic slag particles to larger globules, which in turn force their 
way up and combine with the bulk of the slag. 

The paper produced quite an extended Discussion. Dr. Richards 
called attention to the discussion at the Congress for Testing Materials, 
on the effect of slag enclosures on steel, and urged that the contribution 
presented at this Congress, by those who used and tested the steel, 
should be carefully considered by the manufacturers of steel. 

As to the control of microscopically disseminated particles of slag 
in steel, Dr. Richards made the following suggestions : — First, to 
regulate the composition of the slag carefully ; and, secondlj^ to heat the 
metal in the furnace for some time after the furnace reaction is over, in 
order to let the emulsion separate. Dr. Richards referred in this con- 
nection to the practice of a Bessemer works in Germany, where the 
metal is permitted to rest after the blow is concluded, for a considerable 
time. The cost of this is high, and in his opinion the final solution 
will be to let the metal from oxidising furnaces rest in an electric 
furnace for a definite length of time. The electric furnace in such 
treatment would do nothing else but keep the metal at a high temper- 
ature, and permit the slag particles to separate from the metal. 

Mr. Rogers agreed with Dr. Richards that by heating the metal in 
the furnace and in the ladle, as long as permissible, a marked influence 
would be effected on the slag enclosures ; but this delay would mean an 
enormous expense. To his former remark, that electric steel seemed 
more suitable for rails than for wire, and that they did not feel justified 
in substituting electric steel for open-hearth steel for wire-making, he 
added two reasons for this distinction. Firstly, the increased cost ; 
and, secondly, the difference in the working of the open-hearth steel 
and the electric steel. The difficulties in working, he admitted, might 
possibly l)e due to their inexperience with electric steel. 

Dr. Richards replied that the additional cost of heating the metal 
long enough for it to rest, and to allow the slag to separate was not so 
important, if a " holding " electric furnace was used. The cost would 
lie between 25 and 50 cents a ton. The tests of the engineers have 
shown that the enclosures of slag are very important. 



APPENDIX 229 

Mr. E. R. Taylor referred to the use of a pig-iron mixer, and 
thought that an electric steel-mixer, for letting the metal rest, might be 
the final solution of the difficulty. 

Mr. Speller urged that the time required for letting the metal rest 
would be a serious objection. He thought they had found a partial 
solution, in controlling the condition of the slag when the metal leaves 
the furnace, and in a subsequent circulation of the metal in the ladle. 

B. The Use of Titanium in Foundry Practice with Electric Steel. 

Titanium alloys have been used recently in the manufacture 
of steel for casting purposes, with beneficial results. 

The following extracts give valuable information upon this 
subject : — 

I. 

Recently a very important improvement has been realised by intro- 
ducing into electric steel for castings, special titanium alloys of approxi- 
mately the following compositions : — 

1. Si : 56 per cent. Ti : 36 per cent. 

2. Si : 21 per cent. Ti : 28 per cent. 

3. Si : 10 per cent. Ti : 10 per cent. 

Very small additions of these alloys render the steel perfectly quiet, 
and the castings very dense and free from any blow-holes. The number 
of lost heats is also greatly diminished by this use of titanium alloys. 
— From article by Paul Girod in Metallurgical and Chemical Engineering ^ 
October, 1912. 

n. 

The writer early in 1908 was using titanium alloys for steel made in 
electric furnaces of from 2 to 5 tons capacity, recognising the fact 
that by such treatment only was it possible to obtain a uniform and 
thoroughly deoxidised product. 

Deoxidation is only accomplished in the presence of carbide of calcium 
slag, and every one experienced in the use of the electric furnace knows 
how difficult it is sometimes to form this carbide slag. 

A great feature of the addition of titanium is that this metal by 
oxidation is transformed into titanic acid, which fluxes all the slag held 
in suspension in the steel after it has been tapped into the ladle. The 
proportion of slag so held in the steel is very large when the calcium 
carbide slag has once been formed, the latter being very pasty. While 
ferro-alloys of titanium and silicon combined may be a new way of 



230 APPENDIX 

placing titanium on the market, their use will prove a much more com- 
plicated operation than separate additions of ferro-titanium and ferro- 
silicon. Ferro-titanium alone is very useful, but when an equal 
quantity of silicon is combined with the alloy the silicon is oxidised 
last, if the deoxidation of the bath has not been completed by the 
titanium. If it has, the silicon will be dissolved in the steel, thus 
raising the silicon content to a point very often over the limit imposed 
by the specifications. 

In the case of steel made in the electric furnace, it will very often be 
found that the silicon is too high, a condition brought about either by 
these additions of ferro-silicon during the deoxidation period, or more 
often by the melting of the roof of the furnace, which introduces silica 
into the slag, this silica being in turn reduced by the calcium carbide 
present. —From letter by N. Petinot in Metalh and Ghem. Engineering^ 
November, 1912. 

C. Extracts from an Annual Review Article* upon " Progress in 

Electric Furnaces.''^ 

The inventor points out the possible combinations of elements ; the 
engineer determines which of them are practicable. Ideas which during 
one period of development may be classed as freaks, may at another 
survive those which were at first thought to be more sound. The 
enclosed arc lamp is a good illustration. When shown at the Phila- 
delphia Exhibition in 1884 it was classed as a freak, now it is fast 
replacing its early competitor. The frail Welsbach mantle, wireless 
telegraphy and telephony, are other illustrations. So-called freak ideas 
should therefore not be ignored on general principles ; sometimes they 
are worthy of consideration. 

Fortunately for the development of the electric furnace there are no 
controlling basic patents ; the field is wide open. Improvements in 
the form of inventions, as distinguished from designing and propor- 
tioning, are therefore to be looked for in details rather than in any 
radically new way of converting electric energy into heat, other than 
by means of resistance, although other ways may be possible. 

Aside from the furnace itself, there is of course a very wide field 
open to inventors in devising new thermochemical processes for treat- 
ing materials with the aid of the electric furnace, and it is in this 
direction that valuable improvements may be looked for. 

Considering now the second branch of the development, namely, that 
in which the engineer and scientist are concerned, as distinguished 



APPENDIX 231 

from the inventor, it is probable that it is in this branch that the most 
important progress will be made in the immediate future. It is a 
simple matter to produce an arc between two carbons, thereby getting 
instantaneously, probably the highest temperature which can be pro- 
duced artificially on a commercial scale to day ; but such a device cannot 
or should not be dignified with the title of furnace, nor should it be 
called so when the arc is simply enlarged in scale. The same is true of 
a wire carrying a current by means of which the volatilisation tempera- 
ture of the conductor can be produced in a very short time. To be a 
commercial furnace it is necessary that it operate continuously, with 
reasonable certainty, and with as few stoppages as possible ; also 
with the least possible losses, and with as Httle expert attendance as 
possible. It is here that the work of the engineer becomes important ; 
it is for him to determine how to design, proportion, and construct 
a furnace, so that it may deserve to be classed among engineering 
structures. 

It is therefore in the careful study of the proper designing and pro- 
portioning and operation of furnaces that the greatest and most 
important progress is to be looked for to-day. And it may be said that 
development in these directions has only just begun. 

To calculate proportions requires a knowledge of the physical con- 
stants of materials such as their thermal and often also their electrical 
conductivities, more particularly at high temperatures; also their 
specific heats, their melting and often their volatilisation points ; the 
combination energy when compounds are formed or decomposed ; the 
laws governing the various thermal phenomena, including the flow, 
convection and radiation of heat. Much, if not most, of this funda- 
mental knowledge does not yet exist, or it is only crudely known, or 
perhaps even worse, as it has already been found in some cases, that 
what we thought was known was actually wrong, and had been mis- 
leading us. 

These few illustrations (and many more could be cited) show that 
what might be termed our knowledge of the science of electric 
furnaces is still in a somewhat crude and undeveloped state. Heat is 
a low form of energy to which all other forms tend naturally to 
degenerate ; hence to simply produce heat from energy of the very 
high state of availability of electric energy is no difficult task, as nature 
tends to do it for us. But to do it commercially, without undue waste, 
and so that it will produce the desired product, involves no small 
amount^f knowledge and skill on the part of the engineer, and it is in 



232 APPENDIX 

the acquiring of this knowledge that the development in electric 
furnaces is to be looked for at the present time. 

It is when the engineer can predetermine whether a desired furnace 
operation is possible or not, and if so, whether it is commercial, that 
much progress and fewer failures by the cut-and-try method are to 
be expected. Calculations, when it is possible to make them with 
reasonable certainty, are generally far cheaper than blind cut-and-try 
methods. 

The cost of heat by fuel per degree of temperature increases as the 
temperature rises ; in fact a temperature is reached when the efficiency 
is zero ; that is, where the material no longer gets hotter, the gases 
(including the very large amount of the useless nitrogen) carrying away 
all the heat generated. With electricity generated heat, however, it 
costs no more to produce a high-temperature calorie than one at a low 
temperature. Hence a point must necessarily be reached up to which 
it would pay beat to heat with fuel, and beyond which it would be 
cheapest. to use electric heat, even though generated by coal, not to 
mention the sometimes very valuable advantage of the possibility of a 
neutral atmosphere in the electric furnace.— From ** Electric Furnaces," 
by Carl Hering, in The Electrical Review and Western Electriciarij 
(Chicago) January 7, 1911. 

D. Notes on work of Stassano Furnaces installed at Newcastle, 

England. 

The Stassano Rotary furnaces of the Electro-Flex Steel Co. at 
Dunston-on-Tyne are used in the production of mild steel castings of 
all descriptions used in the engineering trades, ranging in weight from 
a few ounces to one ton. 

The furnaces are lined with magnesite. A lining generally lasts 
three weeks, and will work eighty-five charges of an average of one ton 
before being dismantled for renewal. The average time of working per 
charge is four hours, and the current consumption lies between 1,100 
and 1,200 k.w. hours. 

The charge while in the furnace is under absolute control. Steel 
scrap is charged into the furnace, and a highly basic oxidising slag is 
formed by the addition of iron-ore and lime. This slag being very hot 
and fluid, takes up practically all impurities from the steel, and on 
being raked off it leaves a bath of almost pure iron. At this point 
carbon, manganese, silicon, &c., are added, to produce a resulting metal 
to meet any given specification. 

The metal is sound, of a high degree of purity, and very ductile. 



APPENDIX 



233 



Owing to the great heat obtainable and the consequent fluidity of the 
steel, intricate castings of very thin sections can be produced. A 
peculiarity of the steel made by this process is the excellent physical 
properties it possesses in the unannealed state. Tests taken from a 
side-frame for an electric car gave the following results, imannealed : — 



Chemical Composition, 



Carbon 
Manganese 



0*26 per cent. 
0-50 



Physical Tests, 

Breaking stress 28'9 tons per sq. in. 

Elongation on 2 ins 30'0 per cent. 

Reduction of area . . . .31*6 „ 

The test piece ultimately broke with a fibrous fracture. 

A typical charge taken from the furnace last in commission gave 
the following results of tests : — 

Chemical Analysis. 



Carbon 




. 0'23 per cent. 


Silicon 


» • • « 


. 0-25 


Manganese . 


» • • • 


. 0-76 


Phosphorus . 


• • • • 


. 0015 „ 


Sulphur 


■ • • • 

Physical Tests. 


. 0-016 „ 


Elastic limit 


> • • • 


. 16*0 tons per sq. in. 


Breaking stress 


• • • • 


. 29-0 „ 


Elongation . 


» • • • 


. 300 per cent, on 2 ins. 


Fracture 




. Fibrous. 


Bending test 




.. 180° 



From article by Kershaw in Electrical Times, July 9th, 1913. 



NAME INDEX 



Ambekg, 223 
Anderson, 154 
Arnou, 41 

Benedicks, 14, 208 
Borchers, 83 

Campbell, 3, 6, 59 
Catani, 102 
Chaplet, 155 
Colby, 138, 155 

Eicboff, 60 
Elwell, 34 
Engelhardt, 18, 116 

Ferranti, 14, 205 
Frick, 11, 138 

Girod, 67, 229 
Goldschmidt, 20 
Greene, 157 
Gronwall 23, 140 

Haanel, 23 

Harden, 110, 160 

Harmet, 40 

Bering, 163, 232 

Heroult, 14, 22, 32, 43, 212, 219 

Hiortb, 143, 147 

Joule, 8 

Keller, 14, 21, 128, 210, 218 
Kershaw, 1, 233, 
Kjellin, 11, 106, 119, 

Lane, 100 
Langenberg, 38 
Leffler, 29 
Lindblad, 23, 140 



Lyman, 138 
Lyon, 35, 38 

McBennie, 38 
Moissan, 13 
Moldenke, 99 
Mueller, 76 

Natbusius, 169 
Nau, 168 
Noble, 82 
Nystrom, 29 

Osborne, 50 

Petinot, 230 
Phelps, 33 

Queneau, 171 

Reid, 171 

Richards, 30, 143, 172 

Rochling-Rodenhanser, 10, 106 

Schonawa, 110 
Seager, 84 
Siemens, 11 
Soderberg, 172 
Stalhane, 23, 140 
Stassano, 14, 20, 89, 207 
Stobie, 149 

Swedish Association of Iron Masters, 
27 

Thieme, 120 
Thury, 62 
Tumbull, 44 

Vom Baur, 117 
Von Odelstiem, 26 

Walker, 57 



SUBJECT-MATTER INDEX 



Abstracts of papers and notes, 

Fanctions of the Slag, Amberg, 223 

Progress in Electric Furnaces, 
Hering, 230 

Stassano Farnaces at Newcastle, 
Kershaw, 232 

Use of Titanium, Girod and Petinot, 
229 
Abstracts of patents, 204 

Benedicks, 208 

Ferranti, 206 

Heroult, 212, 216, 219 

Keller, 210, 218, 219 

Siemens, 12 

Stassano, 207 
Alundum as a lining material, 17, 165, 

167 
Anderson furnace, 164 
Annealing, not required for electric 

steel, 5, 232 
Arc farnaces, general principles of, 9 

Anderson, 154 

Chaplet, 155 

Girod, 67 

Gronwall, 23, 140 

Harden, 110, 160 

Harmet, 40 

Heroult, 14, 22, 32, 43, 212, 219 

Keller, 14, 21, 128, 210, 218 

Linblad, 23, 140 

Lyon, 35, 38 

Moissan, 13 

Nathusius, 169 

Reid, 171 

Siemens, 12 

Soderberg, 172 

Stalhane, 23, 140 

Stassano, 14, 20, 89, 207 

Stobie, 149 



Cabbubite, uses of, in steel refining, 

55,70 
Chaplet furnace for iron smelting, 40 
Chaplet furnace for steel refining, 155 
Charge sheets of Chicago 15 - ton 

Heroult furnace, 55 
Chemical and physical tests, 
Girod steel, 83, 187 
Heroult steel, 56, 59, 187 



Chemical and physical tests — cotUd, 
Keller steel, 131, 187 
Bochling-Rodenhauser steel, 121, 

187 
Stassano steel, 104, 187, 233 
Chemistry of refining process, 17, 223 
Chicago, 15-ton Heroult furnace at, 50 
Chrome alloy steel, 5, 83, 105, 121 
Classification of furnaces, 9, 230 
Colby furnace, 155 

Comparative power consumption and 
working costs, 
iron smelting, 18, 19, 20, 41 
steel refining, 18, 19, 173 
Conducting hearth furnaces, 132 
Costs and yields, comparative, for iron 

smelting, 41 
Curves for current and voltage in elec- 
tric refining, 127 

Dabpo, early trials at, 20 

Dolomite for furnace linings, 59, 70, 80, 

112 
Domnarfvet, recent trials at, 26 

Electbicitt supply, systems of, 17, 
53, 62, 72, 101, 103, 127, 135, 140, 151, 
169 
Electrodes, carbon and graphite, 
costs of, 15, 59, 82, 95 
defects of, 15 
design of, 45, 52 
dimensions of, 15, 21, 24, 29, 47, 52, 

162 
general notes on, 15, 16 
heat, losses with, 76 
reduced dimensions in Paragon 

furnace, 160 
substitutes for, 16, 68, 71, 77, 125, 

155, 164 
suspension of, in* Keller furnace, 

136 
water-cooling of, 16, 24, 76, 93 
Equilibrium heat in electric furnaces, 9 

Fluxes for steel refining, 18, 50, 55, 

79, 113, 117, 146 
Formulae for calculating heat and 

temperature, 8 



288 



INDEX 



Foundry, use of electnc furnaces in the, 

61 
Frick furnace for iron smelting, 38 

steel refining, 139 
Future developments of electric re- 
fining, 
Girod furnace, 87 
Heroult furnace, 66 
Stassano furnace, 99 
Future developments of electric smelt- 
ing, 42 

Gas-plants for electric refining fur- 
nace, 61, 153 

General principles of electric refining, 
8,11 

Greene furnace and process, 157 

Gronwall furnace, 140 

Harden furnace, 160 

Hearth electrodes, 76, 132 

Heat, calculation of heat generated, 8 

Hering furnace, 163 

Heroult furnaces and process, 

chemical and physical tests of, 

56, 59 
Chicago 15-ton furnace, charge 
sheets and working costs of, 
56, 59 , 
description of, 50, 53 
method of working the, 53, 55 
future developments of, 66 
general description of, 46, 50 
other installations of, 60, 64 
power consumption of, 65 
Worcester 15-ton furnace, 60 
Heroulf, Shasta County, trials at, 32 
Hiorth furnace, 143 

Historical details of electric furnace 
developments, 14 

Induction furnaces, general principles 
of, 10 
Benedicks, 14 
Colby, 138 
Ferranti, 14, 205 
Frick, 11, 138 
Greene, 157 
Hiorth, 143, 147 
Kjellin, 11, 106, 119 
Kochling-Rodenhaiiser, 10, 106 
Schonawa, 110 

Keller furnace and process, 128 
c )nducting-hearth furnnce, 132 
historical notes on, 128 
power consumption of, 131 
Unieux furnace, description of, 129 



Kjellin furnace and process, 106 

current and voltage curves for, 126 
defects of, 110 
general description of, 106 
methods of work with, 107 
power consumption of, 108 



Linings for refining furnaces, 
cost of, 80 

refractciry materials for, methods 
of using, 16, 17, 46, 51, 59, 70, 
109, 113, 132, 141, 144. 165, 167 
Lists of English and foreign patents, 196 
Lists of fnrna<:es in operation, 188 
Livet, early trials at, 23 
Ludvika, recent trials at, 23 



Magnesitb, ukc of for furnace linings, 
46. 51, 71, 80, 112, 132, 141, 144, 165, 
167 

Moissan's arc furnace, 13 



Nathusius furnace, 169 

Nau furnace, 168 

Nickel steel, 5, 83, 105, 121 



Oil, use of, for heating up electric 
furnaces, 57, 153 



" Paragon " type of furnace, 160 
Patents, abstracts of early 

Benedicks, 208 

Ferranti, 205 

Heroult, 212, 215, 219 

Keller, 210, 218, 219 

Siemens, 12 

Stassano, 207 
Patents for electric furnaces, dat«s and 
numbers of, 

English patents, 196 

Girod patent, 202 

Heroult patents, 201 

Kjellin and Bochling-Rodenhauser 
Patents, 202 
Physical and chemical tests, 

Girod steel, 83, 18^ 

Heroult steel, 56, 59, 187 

Keller steel, 131, 187 

Rochling-Hodenhauser steel, 121, 
187 

Stassano steel, 104, 187, 233 
Pinch effect, use of in furnace design, 
163 



INDEX 



289 



Power consumption for electric refining, 
Colby furnace, 157, 184 
Flick furnace, 139, 184 
Girod furnace, 18, 80, 175 
Heroult furnace, 18, 65, 174 
Hiorth furnace, 184 
Keller furnace, 18, 131, 183 
Kjellin furnace, 108, 180 
Bochling-Rodenhauser furnace, 19, 

117, 181 
Stassano furnace, 18, 94, 178 
Power consumption, electric smelting, 

19,41 
Power supply, systems of electric, 1 7, 53, 
62, 72, 74, 101, 103, 127, 135, 140, 151, 
169 
Progress in electric furnace design, 7, 
230 

QUENEAU furnace, 171 

Raw materials for electric refining, cost 

of, 81, 101, 118, 145 
Refractory materials for furnace linings, 
16, 17, i% 51, 59, 70, 109, 113, 133, 141, 
144, 165, 167 
Reid furnace, 171 

Resistance furnaces, general principles 
of, 9 
Chaplet, 155 
Hering, 163, 232 
Nau, 168 
Queneau, 171 

Rochling-Rodenhauser, 10, 106 
Rochling-Rodenhauser furnace and 
process. 111 
chemical and physical tests of steel 

produced, 121 
current And voltage curves for, 126 
general description of, 111 
methods of work with, 113 
notable installations of, 122 
power consumption of, 117 
working costs of, 118 
Roof, construction of, for refining 
furnaces, 51, 59, 71, 142 

Sault Sainte Marie, early trials at, 23 

Siemens arc furnace, 12 

Silica bricks, use of for roof construc- 
tion, 46, 51, 80 

Silicon, use of alloys in electric refining, 
61, 79, 145 

Slag, functions of, in steel refining, 11, 
18, 47, 54, 61, 77, 78, 112, 158, 168, 
223 



Smelting iron-ore, 

comparative yields and costs, 41 
early trials at Darfo, Li vet and Sault 

Sainte Marie, 20 
recent trials, 23 
Soderberg furnace, 172 
Stassano furnace and process, 

chemical and physical tests of the 

finished steel, 104, 232 
future developments of, 99 
historical notes on, 89 
notable installations of, 100, 232 
power consumption and working 

costs of, 94 
rotary furnaces, earlier types of, 91 
„ „ new forms of, 95 

Stobie furnace, 149 

Sulphur, absence of, in electrically 
refined steel, 64 



Tempebatube, calculation of tempera- 
tures attained, 8 
Temperature of arc furnace, 9 
Tests of raw materials and finished 
steel, 
Heroult steel, 56, 59, 187 
Keller steel, 131, 187 
Rochling - Rodenhauser steel, 121, 

187 
Stassano steel, 104, 187, 232 
Titanium, use of, in foundry practice, 

229 
Transformer coils for induction fur- 
naces, 125, 126 
TroUhatten, recent trials at, 27 
Tungsten alloy steel, 105, 121 



Vanadium steel, 5, 121 



Water-cooling for electrodes, 76, 93 
Worcester, 15-ton Heroult furnace at, 

60 
Working costs for electric refining, 

Girod furnace, 81 

Hiorth furnace, 146 

Keller furnace, 131 

Kjellin furnace, 109 

Rochling-Rodenhauser furnace, 117 

Stassano furnace, 95 
Working costs for electric smelting, 41 

Yields and costs, comparative for iron 
smelting, 41 



BRAPHUKY, AGNKW, ^ CO. LO., PKlNTKRS, LONDON AND TONhRIDOK. 



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Iron and SteeL By J. H. Stansbie, B.Sc. (Lond.), F.I.C. 

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Working of Glass. Bottle. Blown and Pressed. Rolled or 
Plate. Sheet and Crown. Coloured. Optical Glass : Nature 
and Properties, Manufacture. Miscellaneous Products. Ap- 
pendix. Bibliography of Glass Manufacture. Index 

Precious Stones. By W. Goodcrild, M.B., B.Ch. 319 
Pages. With 42 Illustrations. With a Chapter on 
Artificial Stones. By Robert Dykes. 

List of Contents : Introductory and Historical. Genesis r{ 
Precious Stones. Physical Properties. The Cutting and Polish" 
ing of Gems. Imitation Gems and the Artificial Production of 
Preeious Stones. The Diamond. Fluor Spar and the Forms of 
Silica. Corundum, including Ruby and Sapphire. Spinel and 
Chrysoberyl. The Carbonates and the Felspars. The Pyroxene 
and Amphibole Groups. Beryl, Cordierite, Lapis Lazuli and the 
Garnets. Olivine, Topaz, Tourmaline and other Silicates. Phos- 
phates, Sulphates, and Carbon Compounds. 

INTRODUCTION TO THE 

Chemistry and Physics of Building Materials. 

By Alan E. Munby, M.A. 365 Pages. Illustrated. 

Contents : Elementary Science : Natural Laws and Scientific In- 
vestigations. Measurement and the Properties of Matter. Air 
and Combustion. Nature and Measurement of Heat and Its 
Effects on Materials. Chemical Signs and Calculations. Water 
and Its Impurities. Sulphur and the Nature of Acids and Bases. 
Coal and Its Products. Outlines of Geology. Building Materials : 
The Constituents of Stones, Clays and Cementing Materials. Clas- 
sification, Examination and Testing of Stones, Brick and Other 
Clays. Kiln Rezictions and the Properties of Burnt Clays. Plasters 
and Limes. Cements. Theories upon the Setting of Plasters and 
Hydraulic Materials. Artificial Stone. Oxychloride Cement. 
Asphalte. General Properties of Metals. Iron and Steel. Other 
Metals and Alloys. Timber. Paints : Oils, Thinners and Varnishes ; 
Bases, Pigments and Driers. 

Patents, Designs and Trade Marks : The Law 

and Commercial Usage* By Kenneth R. Swan, 
B.A. (Oxon.), of the Inner Temple, Barrister-at-Law. 
402 Pages. 

Contents : Table of Cases Cited — Part I. — Letters Patent. Intro- 
duction. General. Historical. I., II., III. Invention, Novelty, 

( 6 ) 



THE "WESTMINSTER" SERIES 

Subject Matter, and Utility the Essentials of Patentable Invention. 
IV, Specification. V. Construction of Specification. VI. Who 
May Apply for a Patent. VII. Application and Grant. VIII. 
Opposition. IX. Patent Rights. Legal Value. Commercial 
Value. X. Amendment. XI. Infringement of Patent. XII. 
Action for Infringement. XIII. Action tb Restrain Threats. 
XIV. Negotiation of Patents by Sale and Licence. XV. Limita- 
tions on Patent Right. XVI. Revocation. XVII. Prolonga- 
tion. XVIII. Miscellaneous. XIX. Foreign Patents. XX. 
Foreign Patent Laws : United States of America. Germany. 
France. Table of Cost, etc., of Foreign Patents. Appendix A. — 

I. Table of Forms and Fees. 2. Cost of Obtaining a British 
Patent. 3. Convention Countries. Part II, — Copyright in 
Design, Introduction. I. Registrable Designs. II. Registra- 
tion. III. Marking. IV. Infringement. Appendix B. — i. 
Table of Forms and Fees. 2. Classification of Goods. Part 
III, — Trade Marks. Introduction. I. Meaning of Trade Mark. 

II. Qualification for Registration. III. Restrictions on Regis- 
tration. IV. Registration. V. Effect of Registration. VI. 
Miscellaneous. Appendix C. — Table of Forms and Fees. Indices. 
I. Patents. 3. Designs. 3. Trade Marks. 



The Book: Its History and Developments By 

Cyril Davenport, V.D., F.S.A. 266 Pages. With 
7 Plates and 126 Figures in the text. 

List of Contents : Early Records. Rolls, Books and Book 
bindings. Paper. Printing. Illustrations. Miscellanea. 
Leathers. The Ornamentation of Leather Bookbindings without 
Gold. The Ornamentation of Leather Bookbindings with Gold. 
Bibliography. Index. 



The Manufacture of Paper^ By R. W. Sindall, F.C.S., 

Consulting Chemist to the Wood Pulp and Paper Trades ; 
Lecturer on Paper-making for the Hertfordshire County 
Council, the Bucks County Council, the Printing and 
Stationery Trades at Exeter Hall (1903-4), the Institute 
of Printers ; Technical Adviser to the Government of 
India, 1905. 275 Pages. 58 Illustrations. 

Contents : Preface. List of Illustrations. Historical Notice. Cel- 
lulose and Paper-making Fibres. The Manufacture of Paper from 
Rags, Esparto and Straw. Wood Pulp and Wood Pulp Papers. 
Brown Papers and Boards. Special kmds of Paper. Chemicals 
used in Paper-making. The Process of " Beating." The Dye- 
ing and Colouring of Paper Pulp. Paper Mill Machinery. The 
Deterioration of Paper. Bibliography. Index. 

( 7 ) 



THE ^'WESTMINSTER'' SERIES 



Wood Pulp and its Applications^ By C. F. Cross, 

B.Sc, F.I.C., E. J. Bevan, F.I.C, and R. W. Sindall, 
F.C.S. 266 pages. 36 Illustrations. 

Contents: The Structural Elements of Wood. Cellulose as a 
Chemical. Sources of Supply. Mechanical Wood Pulp. Chemical 
Wood Pulp. The Bleaching of Wood Pulp. News and Printings. 
Wood Pulp Boards. Utilisation of Wood Waste. Testing of 
Wood Pulp for Moisture. Wood Pulp and the Textile Industries. 
Bibliography. Index. 



Photography: its Principles and Applications^ 

By Alfred Watkins, F.R.P.S. 342 pages. 98 Illus- 
trations. 

Contents : First Principles. Lenses. Exposure Influences. Prac- 
tical Exposure. Development Influences. Practical Develop- 
ment. Cameras and Dark Room. Orthochxomatic Photography. 
Printing Processes. Hand Camera Work. Enlarging and Slide 
Joking. Colour Photography. General Applications. Record 
Applications, Science Applications. Plate Speed Testing. Pro- 
cess Work. Addenda. Index. 



IN PREPARATION. 

Commercial Paints and Painting* By A. S. Jenn- 
ings, Hon. Consulting Examiner, City and Guilds of 
London Institute. 

Brewing and Distilling* By James Grant, F.S.C 



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