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-i»-^^>*'J» •'

ELEOTEO-THERMAL METHODS OF
mOl^ AND STEEL PRODUCTION

ELECTRO-THERMAL METHODS OF
mON AND STEEL PRODUCTION

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

WITH AN INTRODUCTION BY

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

ILLUSTRATED BY
50 Tables and 93 Diatiravts and Photographs

NEW YOEK

D. VAN NOSTRAND CO.

TWENTY-FIYE PAEK PLACE

1914

^u^^

Vx^

• : / : •. .-

* •

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

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

(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

(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

(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

(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

(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

(d) The Stobie Furnace 149—153

CONTENTS

CHAPTER

Other Types of Electric Furnace for Steel
Eefining (continued)

(a) The

(b) 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 ....

(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—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

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.

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

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.

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

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

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

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).

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

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

Power, "30 e.h.p. year at 50«.

Tjabour .

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

Eepairs, etc

£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

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

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.

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

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

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.

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

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

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.

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.

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. .

Ferro-silicon, 50 per

cent. .

Recarboniser

130

J^'luorspar .

400

Coke dust .

200

Lime, first slag .

600

Lime, second slag

600

Dolomite .

400

Magnesite .

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.

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

. 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.

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.

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

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.

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

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

Slags

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.

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

»>

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

No.

Properties.

Carbon.

Silicon.

Man-
ganese.

Sulphur.

Phos-
pliorus.

other
constituents.

Very soft

0079

106

0-205

0016

0-012

Soft .

0-236

0-180

0-431

0-012

0-010

Middle soft .

0-283

0-208

0-430

0014

0-010

Middle hard .

0-388

0155

0-342

0-011

0-009

Middle hard .

0-463

0-204

0-463

0010

0016

Hard

0-596

0-198

0-302

0017

0005

2 % Nickel .

0076

0-099

0-101

0-014

0010

2-12 % Ni

3 % Nickel soft .

0-06

0123

0-209

0013

0-007

3-47 % Ni

3 % Nickel hard .

0-364

0-144

0-435

0-012

0015

3-41 % Ni

6 % Nickel soft .

0-134

0-148

0376

0-016

0-013

6-25 % Ni

5 % Nickel middle

soft .

0-250

0-157

0-414

0-010

0-015

5-08 % Ni

Nickel-Chrome

0-420

0-199

0-500

0-010

009

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

Tool steel

1-223

0-168

0-224

0-011

0010

Ditto .

1-474

0-199

0-264

0-015

0-007

Ditto

1010

0-219

0-306

008

0009

0-32 % Cr

Ditto

1-277

0-230

0-130

0-009

0-006

0-24 % Cr

Ditto .

1-251

0-176

0-268

0-010

0-008

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

Ditto .

0-689

0-029

0-096

0-012

009

0-46 % Mo
(26'82 % W

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

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

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

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

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.

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

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

£7

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

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-

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.

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.

•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.

•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

•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

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.

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

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

Bails.

Boiler Plata.

s. d.

66 3

. 60 3

, 2

. 5 9i

. 1 i

. 1

. 7

. ii

■ 91

. 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.

Tensile
strength.
Tons per

sq. in.

Elongation.
Per cent.

Con-
traction.
Per cent.

0*55

0-9

0-30

0-03

005

53-2

18-5

31-4

OoO

0-9

0-26

0-026

006

520

190

26-7

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^ *.#

No. of
charge.

Quality.

per

Per

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

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

■sawr

noo

f ijy

90W

- A.'Wr.

■""

"~»

3800

«0

"^-, ,

-''

. X

Ka/( ■

11^

;

4000
kg.

Hot

3400

930

«90

■55WJ

90(}

*00

Vol

_2fiS-

'**■■ ■ 1 ■ ■ ■ r

3600

«6

SflO

■5BWr

840

2400

«0

1
1

8000
kg.

Cold

5100

980

IWO

9{^

JWff

i?9

TTzVunr

"WOO

*9~

y^""""

==55fr:

8000
kg.

Hot

*8W

IffO

TJOO"

.^J

«W«r

-TOO

"WW

)/r

, /{I

W-.

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

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^

1,800 sq. cm.

1,200 sq. cm.

Weight of core .

> .

15 tons

23 tons

Number of primary turns p

er leg

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.

Power factor

0-65

0-50

Voltage ....

250

230

Periodicity (half alternation

s per

second ....

12|

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.

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.

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.

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

9 11

£7

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

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.

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.

•

Wellman

open
hearth.

Martin

open

hearth.

•

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

214

Frick .

780
800

790

Keller .

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

▼

Girod .

•350

•040

1^500

■095
•015

39,000
114,000

50,000
137,000

▼

Stassano.

•267
•380

•048
•038

•031
•026

61,300

4-
90,816

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.,

Tilting basic open

Sheffield.

hearth.

Skinningrove Iron Co.,

•

Talbot.

Yorkshire

Vickers, Ltd., Sheffield.

Melting scrap in
electric furnace.

•

Vickers, Ltd., Sheffield.

Melting scrap in
electric furnace.

Thomas Firth & Sons,

Melting scrap in

Ltd., Sheffield.

electric furnace.

Tiake & Elliot, Braintree.

Melting scrap in
electric furnace.

Austria-

Kaernthner Eisen &

Melting scrap in

Hungary

Stahlwerke.

electric furnace.

Gebr. Bohler & Cie, A. G.,

Melting scrap in

Kapfenberg.

electric furnace.

Gehr. Bohler & Cie, A. G.,

Melting scrap in

Kapfenberg.

electric furnace.

Briider Tiapp, Rotten-

Melting scrap in

mann. Works Steier-

electric furnace.

mark.

Banner & Co., Juden-

Melting scrap in

berg.

electric furnace.

Royal Himgarian Arsenal.

Melting scrap in
electric furnace.

Belgium

Soci6t6 des Usines M^tal-
lurgiques du Hainaut,
CouiUet.

Basic open hearth.

Soci6t6 Anonyme Ougr6e-

Basic open hearth.

Marihay^, near Li^ge.

France

Soci6t6 Electro-Metallur-

Melting scrap in

gique Fran^aise, ^a

electric furnace.

Praz, Savoie.

Acieries du Saut du Tarn,

Basic open hearth.

St. Ju^ry.

Usine M6tallurgique de la

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.

Basic open hearth.

Deutscher Kaiser Stahl-

Basic open hearth.

werke, Bruckhausen.

Deutscher Kaiser Stahl-

Basic open hearth.

werke, Bruckhausen.

Stahlwerke Thyssen

Basic open hearth.

Hagendingen (Lothr.).

Stahlwerke Thyssen

Basic open hearth.

Hagendingen (Lothr.).

Stahlwerke Richard Lin-

Tilting basic.

denberg, Remscheid-

Hasten.

Stahlwerke Richard Lin-

Open hearth.

denberg, Remscheid-

H as ten.

Bisujarckhiitte, Upper

Melting scrap in

Silesia.

electric furnace.

Bismarckhiitte, Upper

Melting scrap in

Silesia.

electric furnace.

Mannesmann Rohren

Melting scrap in

Werke, Saarbrucken,

electric furnace.

Burbach.

Rombacher Hiittenwerke,

Open hearth.

Rombach.

Rombacher Hiittenwerke,

Open hearth.

Rombach.

Deutscher Luxemburg-

Open hearth.

ische, Dortmund.

Deutscher Luxemburg-

Open hearth.

ische, Dortmund.

Italy .

Societa Tubi Mannes-

Melting scrap in

mann, Dalmine.

electric furnace.

Society Tubi Mannes-

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

Molten Martin

Hutten-&-Tnechanischen

steel.

Werke, Sormovo.

Soci6t^ G^n^rale des Hts.

Molten Martin

Fourneaux & Acieries

steel.

en Russie, Makejewka.

Sweden

Aktiebolaget Hereults

Meltiug scrap in

elektriska Stal, Kortf ors.

electric furnace.

Switzerland .

Georg Fischer, Schaff-

Melting scrap in

haiisen.

electric furnace.

Canada

Electro Metals, Welland,

Melting scrap in

Ontario.

electric furnace.

Electro Metals, Welland,

Melting scrap in

Ontario.

electric furnace.

United States

United States Steel Cor-
poration, S. Chicago.

Bessemer.

United States Steel Cor-

Basic open hearth.

poration, Worcester.

Firth-Stirling Co., Syra-

Melting scrap in

cuse, New York.

electric furnace.

Firth-Stirling Co., Syra-

Melting scrap in

cuse, New York.

electric furnace.

Halcomb Steel Co., Syra-

Tilting basic open

cuse, New York.

hearth.

Crucible Steel Co., of

Basic open hearth.

America, Pittsburg, Pa.

Crucible Steel Co., of

Basic open hearth.

America, Pittsburg, Pa.

Mexico

Cie. Mexicano Aciero &

Melting scrap in

Productos Chemicos.

electric furnace.

Cie. Mexicano Aciero &

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

2
2

66|

(16
Furnaces.)

Erecting

Tons.

(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.

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.

High-

verein

grade

Le Gallais Metz &

3,500

Do.

steels

Cie. •

and

Dornineldingen

3,500

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.

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.

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.

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.

narlvet, Gysinge

Norway —

Stavanger Elektro-

4,000

Rochling

Do.

Hot

stalverk, A. S.

Roden-
hauser

scrap.

Spain —

Urigoilia e Hija

1,500

Kjellin

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.

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.

75 kgs.

Welland, Ontario

(At pre-
sent not

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)

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 .

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,

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 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 .

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.

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

100269
July 21, 1906

Conductors ar-
ranged to op-
pose leakfield.

»»

None

102575
Dec. 11, 1906

Channels for re-
sistance heat-
ing.

»»

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

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

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.

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

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

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 : —

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.

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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Gas Engines^ By W. J. Marshall, Assoc. M.I.Mech.E.,
and Capt. H. Riall Sankey, R.E. (Ret.). M.Inst.C.E.,
M.I.Mech.E. 300 Pages, 127 Illustrations.

List of Contents : Theory of the Gas Engine. The Otto Cycle. The
Two Stroke Cycle. Water Cooling of Gas Engine Parts. Ignition.
Operating Gas Engines. The Arrangement of a Gas Engine Instal-
lation. The Testing of Gas Engines. Governing. Gas and Gas
Producers. Index.

Textiles* By A. F. Barker, M.Sc, with Chapters on the
Mercerized and Artificial Fibres, and the Dyeing of
Textile Materials by W. M. Gardner, M.Sc, F.C.S. ;
Silk Throwing and Spinning, by R. Snow; the Cotton
Industry, by W. H. Cook ; the Linen Industry, by F.
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Contents : The History of the Textile Industries ; also of Textile
Inventions and Inventors. The Wool, Silk, Cotton, Flax, etc..
Growing Industries. The Mercerized and Artificial Fibres em-
ployed in the Textile Industries. The Dyeing of Textile Materials.
The Principles of Spinning. Processes preparatory to Spinning.
The Principles of Weaving. The Principles of Designing and
Colouring. The Principles of Finishing. Textile Calculations.
The Woollen Industry. The Worsted Industry. The Dress
Goods, Stuff, and Linings Industry. The Tapestry and Carpet
Industry. Silk Throwing and Spinning. The Cotton Industoy.
The Linen Industry historically and commeFcially considered.
Recent Developments and the Future d the Textile Industries.
Index.

Soils and Manures* By J. Alan Murray, B.Sc. 367

Pages. 33 Illustrations.

Contents : Introductory. The Origin of Soils. Ph3^al Proper-
ties of Soils. Chemistry of Soils. Biology of Soils. Fertifity.
Principles of Manuring. Phosphatic Msuiures. Phosphonitro-
genous Manures. Nitrogenous Manures. Potash Manures.
Compound and Miscellaneous Manures. General Manures. Farm-
yard Manure. Valuation of Manures. Composition aad Manural
Value of Various Farm Foods.

( I )

THE " WESTMINSTER '* SERIES

CoaL By James Tonge, M.I.M.E., F.G.S., etc. (Lecturer

on Mining at Victoria University, Manchester). 283

Pages. With 46 Illustrations, many of them showing the

Fossils found in the Coal Measures.

List of Contents : History. Occurrence. Mode of Formation
of Coal Seams. Fossils of the Coal Measures. Botany of the
Coal-Measure Plants. Coalfields of the British Isles. Foreign
Coalfields. The Classification of Coals. The Valuation of Coal.
Foreign Coals and their Values. Uses of Coal, The Production
of Heat from Coal. Waste of Coal. The Preparation of Coal
for the Market. Coaling Stations of the World. Index,

Iron and SteeL By J. H. Stansbie, B.Sc. (Lond.), F.I.C.

385 Pages. With 86 Illustrations.

List of Contents : Introductory. Iron Ores. Combustible and
other materials used in Iron and Steel Manufacture. Primitive
Methods of Iron and Steel Production. Pig Iron and its Manu-
facture. The Refining of Pig Iron in Small Charges. Crucible
and Weld Steel. The Bessemer Process. The Open Hearth
Process. Mechanical Treatment of Iron and Steel. Phj^ical
and Mechanical Properties of Iron and Steel. Iron and Steel
under the Microscope. Heat Treatment of Iron and Steel. Elec-
tric Smelting. Special Steels. Index.

Timber* By J. R. Baterden, Assoc.M.Inst.CE. 334

Pages. 54 lUustrations.

. Contents : Timber. The World's Forest Supply. Quantities of
Timber used. Timber imports into Great Britain. European
Timber. Timber of the United States and Canada. Timbers
of South America, Central America, and West India Islands. Tim-
bers of India, Burma, and Andaman Islands. Timber of the
Straits Settlements, Malay Peninsula, Japan and South and
West Africa. Australian Timbers. Timbers of New Zealand
and Tasmania. Causes of Decay and Destruction of Timber.
Seasoning and Impregnation of Timber. Defects in Timber and
General Notes. Strength and Testing of Timber. " Figure " in
Timber. Appendix. Bibliography.

Natural Sources of Power. By Robert S. Ball, B.Sc,

A.M.Inst.C.E. 362 Pages. With 104 Diagrams and

Illustrations.

Contents : Preface. Units with Metric Equivalents and Abbre-
viations. Length and Distance. Surface and Area. Volumes.
Weights or Measures. Pressures. Linear Velocities, Angular
Velocities. Acceleration. Energy. Power. Introductory
Water Power and Methods of Measuring. Application of Water
Power to the Propulsion of Machinery. The Hydraulic Turbine.

{ 2 )

THE "WESTMINSTER" SERIES

Various Types of Turbine. Construction of Water Power Plants.
Water Power Installations. The Ketrulation of Turbines. \^'ind
Pressure, Velocity, and Methods of Measuring. The Application
of Wind Power to Industry. The Modem Windmill. Con-
structional Details. Power of Modern Windmills. Appendices.
A,B,C Index.

Electric Lamps. By Maurice Solomon, A.C.G.I.,
A.M.I.E.E. 339 Pages. 112 Illustrations.

Contents : The Principles of Artificial Illumination. The Produc-
tion of Artificial Illumination. Photometry. Methods of Testing.
Carbon Filament Lamps. The Nemst Lamp. MetalUc Filament
Lamps. The Electric Arc. The Manufacture and Testing of Arc
Lamp Carbons. Arc Lamps. Miscellaneous Lamps. Compari-
son of Lamps of Different Types.

Liquid and Gaseous Fuclst and the Part they play
in Modern Power Production* By Professor

Vivian B. Lewes, F.I.C, F.C.S., Prof, of Chemistry,

Royal Naval College, Greenwich. 350 Pages. With 54

Illustrations.

List of Contents : Lavoisier's Discovery of the Nature of Com-
bustion, etc. The Cycle of Animal and Vegetable Life. Method
of determining Calorific Value. The Discovery of Petroleum
in America. Oil Lamps, etc. The History of Coal Gas. Calorific
Value of Coal Gas and its Constituents. The History of Water
Gas. Incomplete Combustion. Comparison of the Thermal
Values of our Fuels, etc. Appendix. Bibliography. Index.

Electric Power and Traction. By F. H. Davies.

A.M.I.E.E. 299 Pages. With 66 Illustrations.

List of Contents : Introduction. The Generation and Distri-
bution of Power. The Electric Motor. The Application of
Electric Power. Electric Power in Collieries. Electric Power
in Engineering Workshops. Electric Power in Textile Factories.
Electric Power in the Printing Trade. Electric Power at Sea.
Electric Power on Canals. Electric Traction. The Overhead
System and Track Work. The Conduit System. The Surface
Contact System. Car Building and Equipment. Electric Rail-
ways. Glossary. Index.

Decorative Glass Processes. By Arthur Louis

DuTHiE. 279 Pages. 38 Illustrations.

Contents : Introduction. Various Kinds of Glass in Use : Their
Characteristics, Comparative Price, etc. Leaded Lights. Stained
Glass. Embossed Glass. Brilliant Cutting and Bevelling. Sand-
Blast and Crystalline Glass. Gilding. Silvering and Mosaic.
Proprietary Processes. Patents. Glossary.

( 3 )

tH£ ^' W£StMiNStER ^^ SERIES

Town Gas and its Uses for the Production of
Light, Heat, and Motive Power* By W. H. Y.

Webber, C.E. 282 Pages. With 71 Illustrations.

List of Contents : The Nature and Properties of Town Gas. The
History and Manufacture of Town Gas. The Bye-Products of
Coal Gas Manufacture. Gas Lights and Lighting. Practical
Gas Lighting. The Cost of Gas Lighting. Heating and Warm-
ing by Gas. Cooking by Gas. The Healthfulness and Safety
of Gas in all its uses. Town Gas for Power Generation, including
Private Electricity Supply. The Legal Relations of Gas Sup-
pliers, Consumers, and the Public. Index.

Electro-Metallurgy. By J. B. C. Kershaw, F.I.C.
318 Pages. With 61 Illustrations.

Contents : Introduction and Historical Survey. Aluminium.
Production. Details of Processes and Works. Costs. Utiliza-
tion. Future of the Metal. Bullion and Gold. Silver Refining
Process. Gold Refining Processes. Gold Extraction Processes.
Calcium Carbide and Acetylene Gas. The Carbide Furnace and
Process. Production. Utilization. Carborundum. Details of
Manufacture. Properties and Uses. Copper. Copper Refin-
ing. Descriptions of Refineries. Costs. Properties and Utiliza-
tion. The Elmore and similar Processes. Electrolytic Extrac-
tion Processes. Electro-Metallurgical Concentration Processes.
Ferro-alloys. Descriptions of Works. Utilization. Glass and
Quartz Glass. Graphite. Details of Process. Utilization. Iron
ahd Steel. Descriptions of Furnaces and Processes. Yields and
Costs. Comparative Costs. Lead. The Salom Process. The Betts
Refining Process. The Betts Reduction Process. White Lead Pro-
cesses. Miscellaneous Products. Calcium. Carbon Bisulphide.
Carbon Tetra-Chloride. Diamantine. Magnesium. Phosphorus.
Silicon and its Compounds. Nickel. Wet Processes. Dry
Processes. Sodium. Descriptions of Cells and Processes. Tin.
Alkaline Processes for Tin Stripping. Acid Processes for Tin
Stripping. Salt Processes for Tin Stripping. Zinc. Wet Pro-
cesses. Dry Processes. Electro-Thermal Processes. Electro -
Galvanizing. Glossary. Name Index.

Radio-Telegraphy. By C. C. F. Monckton, M.I.E.E.

389 Pages. With 173 Diagrams and Illustrations.

Contents : Preface. Electric Phenomena. Electric Vibrations.
Electro-Magnetic Waves. Modified Hertz Waves used in Radio-
Telegraphy. Apparatus used for Charging the Oscillator. The
Electric Oscillator : Methods of Arrangement, Practical Details.
The Receiver : Methods of Arrangement, The Detecting Ap-
paratus, and other details. Measurements in Radib-Telegraphy.
The Experimental Station at Elmers End : Lodge-Muirhead
Sjrstem. Radio - Telegraph Station at Nauen : Telefunken
System. Station at Lyngby : Poulsen System. The Lodge-

(4)

THE "WESTMINSTER" SERIES

Muirhead System, the Marconi System, Telefunken System, and
Poulsen System. Portable Stations. Radio-Telephony. Ap-
pendices : The Morse Alphabet. Electrical Units used in this
Book. International Control of Radio-Telegraphy. Index.

India-Rubber and its Manufacture^ with Chapters
on Gutta-Percha and Balata* By H. L. Terry,

F.I.C., A5Soc.Inst.M.M. 303 Pages. With Illustrations.

List of Contents : Preface. Introduction : Historical and
General. Raw Rubber. Botanical Origin. Tapping the Trees.
Coagulation. Principal Raw Rubbers of Commerce. Pseudo-
Rubbers. Congo Rubber. General Considerations. Chemical
and Physical Properties. Vulcanization. India-rubber Planta-
tions. India-rubber Substitutes. Reclaimed Rubber. Washing
and Drying of Raw Rubber. Compounding of Rubber. Rubber
Solvents and their Recovery. Rubber Solution. Fine Cut Sheet
and Articles made therefrom. Elastic Thread. Mechanical
Rubber Goods. Sundry Rubber Articles. India-rubber Proofed
Textures. Tyres. India-rubber Boots and Shoes. Rubber for
Insulated Wires. Vulcanite Contracts for India-rubber Goods.
The Testing of Rubber Goods. Gutta-Percha. Balata. Biblio-
graphy. Index.

The Railway Locomotive. What It Is, and Why It is

What It Is. By Vaughan Pendred, M.Inst.M.E.,
Mem.Inst.M.I. 321 Pages. 94 Illustrations.

Contents : The Locomotive Engine as a Vehicle — Frames. Bogies.
The Action of the Bogie. Centre of Gravity. Wheels. Wheel
and R^. Adhesion. Propulsion. Counter-Baiancing. The Loco-
motive as a Steam Generator — ^The Boiler. The Construction of the
Boiler. Stay Bolts. The Fire-Box. The Design of Boilers.
Combustion. Fuel. The Front End. The Blast Pipe. Steam
Water. Priming. The Quality of Steam. Superheating. Boiler
Fitting^. The Injector. The Locomotive as a Steam Engine —
Cylinders and Valves. Friction. Valve Gear. Expansion. The
Stephenson Link Motion. Walschaert's and Joy's Gears. Slide
Valves. Compounding. Piston Valves. The Indicator. Ten-
ders. Tank Engines. Lubrication. Brakes. The Running Shed.
The Work of the Locomotive.

Glass Manufacture* By Walter Rosenhain, Superin-
tendent of the Department of Metallurgy in the National
Physical Laboratory, late Scientific Adviser in the Glass
Works of Messrs. Chance Bros. & Co. 280 Pages. With
Illustrations.

Contents : Preface. Definitions. Physical and Chemical Qualities,
Mechanical, Thermal, and Electrical Properties. Transparency

( 5 )

THE "WESTMINSTER" SERIES

II Tm- II ._ - - -- - - -I - -IfT^ I !!■■ IMB IBM^ ,_ I ^

and Colour. Raw materials of manufacture. Crucibles and
Furnaces for Fusion. Process of Fusion. Processes used in
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

( 8)

* I

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