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Full text of "Coke-oven tars of the United States"

Issued February 7, 1912. 



U. S. DEPARTMENT OF AGRICULTURE, 

OFFICE OF PUBLIC ROADS— Circular No. 97. 
LOGAN WALLER PAGE, Director. 



COKE -0 YEN TARS 0E THE 
UNITED STATES. 



BY 



PRfiVOST HUBBARD, 

Chemist, Office of Public Roads. 




h rSpVlCK! 



LETTER OF TRANSMITTAL 



United States Department of Agriculture, 

Office of Public Roads, 
Washington, D. C, October 19, 1911. 
Sir: I have the honor to transmit herewith the manuscript of a 
circular by Mr. Prevost Hubbard, chemist in this office, entitled 
"Coke-Oven Tars of the United States." This publication gives the 
results of examinations of all the coke-oven tars at present manu- 
factured in this country, together with a brief discussion of their 
properties in relation to their use as road materials. I respectfully 
request that this manuscript be published as Circular 97 of this office. 
Respectfully, 

Logan Waller Page, 

Director. 
Hon. James Wilson, 

Secretary of Agriculture. 



URL Un ' 



COKE-OYEX TARS OF THE UNITED STATES. 



The rapidly increasing use in this country of refined coal tar in the 
treatment and const miction of roads and the fact that an immense 
quantity of coal tar will ultimately become available for this purpose 
through the installation of by-product coke ovens make it highly 
desirable to obtain accurate information as to the properties of coke- 
oven tars which are being produced at present. Attention was 
called by the author to the importance of this subject in a recent 
publication, 1 as follows: 

While, in the manufacture of con] gas. the production of tar is 
absolutely unavoidable, this is not true of the manufacture of coke 
for metallurgical purposes. There are two general types of coke 
ovens in use at present, in one of which no attempt is made to recover 
the volatile products of the coal. This is the oldest form of oven, 
known as the "beehive," and is extensively used in this country 
to-day. Tt is constructed of brick and as its name implies has the 
form of a beehive. Bituminous coal is placed in this oven or kiln 
and a part of it burned in order to carbonize the remainder, while the 
volatile products, such as gas. ammonia, and tar, are allowed to escape 
through an opening in the top of the kiln, where they are lost in flame 
and smoke. 

Coke ovens in which the by-products are saved are now used to 
some extent in this country, and sooner or later will undoubtedly 
replace the old-style oven entirely, and thus increase our output of 
tar enormously. The reason that they have not been more generally 
adopted in tlii- country is that in the United States tars are of much 
less economic importance than in the European countries, where 
great chemical industries are based upon the utilization of this 
material. < rermany in particular is far in advance of us in this Held 
and exports to this country alone coal-tar products to the value of 
• ral million dollars each year. With the development of the 
road-tar industry, which promises to consume vast quantities of tar, 
and the aecessity for refining such tars before use, the general adoption 
of by-product ovens is only a matter of time. What this will mean 
in the increase in tar production can be imagined from the fact that in 
1908, oiii of b total of over 26,000,000 t<>ns of coke produced in coke 
oven-, only a little over 1,000,000 tons were obtained from by-product 

1 1 M0, New Vol 

:i 



4 COKE-OVEN TARS OF THE UNTTED STATES. 

ovens. About 22,000,000 Ions of coke were, therefore, produced 
without recovery of the tar. As the average yield of coke per ton of 
coal was 66 per cent, this would represent the consumption of over 
33,000,000 tons of coal. Upon the basis of a yield of 10 gallons of 
tar per ton of coal, it may be seen that over 330,000,000 gallons of 
tar were lost in 1908 which might have been saved. As the actual 
production of coal tar both from coke ovens and gas houses amounted 
to about 101,000,000 gallons, it is evident that over three-fourths of 
our possible production of tar as a by-product was lost during that 
year. At a valuation of 2> s cents per gallon, this means a loss of over 
$8,000,000. With such an increase in production, however, the 
monetary value of coal tar would have dropped, so that this figure 
may be somewhat exaggerated. In any event, at a conservative 
estimate, the tar lost each year from nonrecovery coke ovens is 
sufficient to build 9,000 miles of tar macadam road 15 feet wide. 

This estimate was based on data taken from reports of the United 
States Geological Survey. In a later report by Parker, 1 it is shown 
that over 53,000,000 tons of coal were consumed in beehive ovens in 
1910, so that on the same basis it would appear that over 530,000,000 
gallons of tar were lost during that year. The output of tar from by- 
product coke ovens, however, has also continued to increase, as 
shown by the following figures taken from this report: 

Tar obtained from by-product coke ovens. 

Gallons. 

1908 42, 720, 609 

1909 60, 126, 006 

1910 66, 303, 214 

The tar thus produced in 1910 was valued at $1,599,453, or about 
2.4 cents per gallon. It is evident, therefore, that the value of the 
tar lost during that year by the use of beehive ovens amounted to 
approximately $12,000,000. That the use of by-product ovens is 
increasing in greater proportion than the use of the beehive oven is 
shown by the fact that for the former type the increase in 1910 over 
1909 in tons of coke produced was 14.13 per cent, while the production 
from beehive ovens increased by only 4.57 per cent. Parker adds, 
however: 

While noteworthy progress has been made in the substitution of modern retort-oven 
practice for the wasteful and what should be obsolete beehive or partial-combustion 
method of coke making in the United States, this country is still much behind European 
countries in this regard. 

He says further: 

The yield of coal in coke in retort ovens exceeds that obtained in beehive or other 
partial-combustion ovens by about 15 per cent, and generally the quality of the coke 
is improved. 

i The Manufacture of Coke in 1910, United States Geological Survey. 



COKE-OVEN TABS OF THE UNITED STATES. 

In order to determine the character of coke-oven tars at present 
being produced in the United States, it was first necessary to obtain 
samples from all of the known plants, and for tins purpose reference 
was made to a list of by-product and retort coke-oven plants of the 
United States and Canada (Jan. 1, 1910), winch was kindly loaned to 
the author by Mr. Parker in advance of its publication. 1 Letters 
were then written to each plant asking for the following information: 

(1) a. At what maximum temperature are your retorts fired in your ovens? 

In your ovens? 

b. What is the maximum temperature to which the charge of coal is brought in your 
ovens? In your ovens? 

(2) What is the specific gravity of your crude tar in your ovens'.' In your 

ovens? 

(3) What percentage of free carbon is found in your crude tar from your ovens? 

From your ovens? 

Will you furnish us for examination a L-gallon sample of your crude tar from 
your ovens'.' From your ovens? To be sent at our expense. 

Very courteous replies were received from the manufacturers, and in 
practically every ease samples of tar were also forwarded. The blanks 
in these questions were Idled out by inserting the names of the type or 
tvpes of ovens operated by the manufacturer to whom they were sent. 
It was found that, where two types of ovens were operated at the same 
plant, no attempt was made to separate the tar, and the entire output 
was run into a common well. In such cases the sample of tar sub- 
mitted was a mixture obtained from both ovens. The report of these 
samples i-, given at the bottom of Table 1. 

The questions concerning temperature were asked because criticism 
from an authoritative source had been received with regard to a state- 
ment made by the author in a former publication'-' to the effect that 
in the production of tar from b>y-produc1 coke ovens " carbonization is 
conducted at a lower temperature than in tin manufacture of coal gas. 
The resulting tar, therefore, contains a smaller amount of free carbon, 
averaging from 3 to 10 per cent * * *." But little reliable infor- 
mation on this subject could be obtained from published literature, 
although the opinion seemed to prevail that carbonization in by- 
product coke ovens is conducted at a lower t einperat ure than in mod- 
ern gas-house practice. Thus, according to Lunge, 1 " Ililgenstock 
(J. Gasbeleucht., 1902, 617) attributes the notorious difference be- 
t ween gas-tar and coke-oven t ar wii h respeel of t heir contents of free 
carbon and other products of pyrogenetic decomposition to the fact 

that in coke ovens the escaping vapors do not attain temperatures 

above 600°( '.. and t hat t hey are, moreover, protected againsl decompo- 
sition by the dilution of the heavj vapors, slowly given off from the 

i Mineral Rcaoam of the United -'.'• , 1909, Part n, pp. 240-242, Unit Oeologioal Survey. 

i CtmdtfM, Office oi Public Road , U. 8. Department ol Agriculture, | 

■ o >i T ■• in i v tnmonJ i, Itb ed., pari I, p. 28, \ an Noatrand. 



6 



COKE-OVEN TARS OF THE UNITED STATES. 

Table I. — Analyses of crude coke-oven tors 



General information. 



Answers to questions. 



Sum I 
No. , 



I ompany and location. 



Type of 
oven. 



Maximum 

temperature 
of firing 
retorts. 



Maximum 
tempera- 
ture to 
which coal 
is brought. 



Specific 

gravity 

of crude 

tar. 



Per cent 
of free 
carbon 
in tar. 



5126 
5123 
5124 

5137 
5121 

5125 

5128 
5200 

51 89 

51*30 



5081 
5095 

5083 
5159 

5107 
5086 
5078 
5087 

5109 



5188 
5404 



5108 



Solvay Process Co., Syracuse, N. Y.. 

Semet-Solvay Co., Pennsylvania 

Steel Co., Steelton, Pa. 
Semet-Solvay Co., National Tube 

Co., Benwood, W. Va. 
Semet-Solvay Co., Milwaukee Coke 

& Gas Co. , Mil waukee , W is. 
Semet-Solvay Co., Pennsylvania 

Steel Co., Lebanon, Pa. 
By-Prod ucts Coke Corporation, 

South Chicago, 111. 

Semet-Solvay Co., Detroit, Mich 

Semet-Solvey Co., Empire Coke Co., 

Geneva, N. Y. 
Semet-Solvay Co., Dunbar Furnace 

Co., Dunbar, Pa. 
Semet-Solvay Co., Central Iron & 

Coal Co., Tuscaloosa, Ala. 
I Philadelphia Suburban Gas & Elec- 
\\ trie Co., Chester, Pa. 

j Semet-Solvay Co., Ensley, Ala 

The New England Gas & Coke Co., 
Everett, Mass. 
A Lackawanna Steel Co. , Lackawanna 
\ Iron & Steel Co., Lebanon, Pa. 

Dominion Tar & Chemical Co., Syd- 
ney, Nova Scotia. 
,/ Hamilton Otto Coke Co., Hamilton, 
\ Ohio. 

i Carnegie Steel Co. , South Sharon, Pa 
; I Maryland Steel Co., Sparrows Point, 
\ Md. 

Citizens' Gas Co., Indianapolis, Ind. 

(Pittsburg Gas & Coke Co., The 
United Coke & Gas Co., Glassport, 
Pa. 

Zenith Furnace Co., Duluth, Minn 



Semet-Sol- 
vay. 
do 

....do 

....do 

....do 

do 

do 

do 

do 

do 

L...do 



....do 

Otto Hoff- 
man. 

|....do 

...do 

....do 

[United. 
[ Otto. 

do.... 

...do.... 



1050-1450° C. 
1050-1450° C. 
1050-1450° C. 
1050-1450° C. 
1050-1450° C. 

1050-1450° C 

1050-1450° C 
1050-1450° C. 

1050-1450° C 

1250° C 



1050° C. 



1250° C. 
i 1100° C. 



11000° C 

[(1800° F.).. 
( 2 ) 



(1111° c... 
\(2000° F.)... 

(1666° C 

\(3000° F.).. 

(1333° C 

V2400° F.) . 

11222° C 

\(2200°F.).. 



Illinois Steel Co. , Joliet , 111 . 



Camden Coke Co., Camden, X. J. 



...do 

....do.... 

Koppers . 
• do 



(Illinois Steel Co. , Indiana Steel Co. 
\ Gary, Ind. 

I Otto Hoff- 
man. 
United 
Otto. 
(OttoHoff- 
j man.. 
(United 
1 1 Otto. 
'(United 

Lackawanna Steel Co. , Buffalo, N. Y . \ ° tt0 - 

iRothberg . 



Cambria Steel Co., Johnstown, Va 



(-) 

(1222-1277° C, 
«200 - 2300° 
■I (F.) 

11444° C 

\(2800°F.).. 

1100° C 



950-1150°C. 
950-11.50° C 
950-1150° C 
950-1150° C 
950-1150° C. 

950-1150° C 

950-1150° C 
950-1150° C. 

950-1150 C°. 

1150° C.... 

1000° C... 

1150° a... 

1 1200° C . . . 

1000° a... 

(1800° F.). 

( 2 ) 
mi a... 

(2000° P.). 

1444° C... 
(2600° F.). 
1222° a... 
(2200° P.). 
1222° C. . . . 
(2200° F.). 

( 2 ) 



12-1. 21 
12-1.21 
12-1.21 
12-1.21 
, 12-1. 21 



1.12-1.21 



(1000° C 

\(1800°F.).. 

(1222° C 

1(2200° F.)... 

(1111° C 

\(2000° F.)... 
(1111° c. 



|\(2000° F.).. 

'fiooo a 



{(1800° F.) 
|(1000° c... 
\(1800° F.) 



J ( 2 ) 

1388° a... 

i (2500° F.). 
i (880 - 950° 

I c. 

833° C 

(1500° F.). 
1055° C. . . . 
(1900° F.). 
i 1111° C .. 
(2000° F.). 
i 1111°C... 
(2000° F.). 
1000° C... 
(1800° F.) 
1000° C... 
(1800° F.) 



i. 12-1. 21 
1.12-1.21 

L. 12-1. 21 

1.17 

1.161 

(20° C ) 

1.17 

(15° C.) 
1.17 

1.10 
1.170 



1.2 

3 1.19 

Vl. 14-1. IS 

( (50° F.I 
\ 1.207 
10° C 

( 2 ) 



< 1.174 
1.169 



1.20-1.30 
5 (1.221) 



3-12 
3-12 
3-12 
3-12 
3-12 

3-12 

3-12 
3-12 

3-12 

5.72 



16-24 

10-1; 

6 16.0 

7. 09-10. 64 
3 8-10 
4-5 

16.59 

( 2 ) 

12-15 

4. 35 



7-9 

(7.3) 



1 Approximately. 

2 No information. 

3 Varies with coal. Coal with 28 per cent of volatile matter used. 
« With H 2 0. 

& At present. 
6 Variable. 
' Trace. 



8 Trace of solids. 

» Distillate, solid. 
io Distillate, one-fourth solid. 
" Distillate, nine-tenths solid. 
12 Distillate, three-fourths solid, 
is Distillate, eight-ninths solid. 
u Distillate, one-half solid. 



COKE-OVEN TARS OF THE UNITED STATES. 
produced in the United States and Canada. 



Examination. Office of Public Roads. 



Spe- 
cific 
gravity 
of tar, 
25'' C. 



Per 

cent 
of free 
car- 
bon. 



1.195 
1.206 
1. 176 
1. 168 
1. 173 



7.76 
8.77 
7.14 
0.10 
4.71 



1. 191 7. 49 



1. 169 
1.159 



1.181 
1.159 



6.56 
6.07 



8.85 
5.05 



Per 
cent 
of ash, 



1.141 3.96 



1. 17.'. 


6.90 


1.160 


13. 94 


1.214 


14. 05 


1.143 


10.81 



1. li.O 

1. 191 
1. 179 
1.133 

1 176 



1.171 

I 1'.'. 



I. 182 



i 211 



I 21" 



8.37 

7 

8.49 

5.21 

10.53 

u 1- 

2. 7:t 
11 30 

12, 10 

I., H<l 



Per 
cent 
soluble 
in cs-2, 
includ- 
ing 
HjO. 



Distillation results 



0.12 
.0 
.04 
.05 
.06 

.03 

.11 
.08 

.02 

.02 



.06 
.00 

.13 
.05 

.06 

.03 
.03 

.07 

.04 



92. 12 
91.16 



ss 



1.0 
1.0 



92.82 l.l 
93.85| 1.8 



93. 33 
93.85 



91.13 



P) 

6.' 
4.0 

2.0 



94.93 3.2 



93.04 
86.06 



85.82 
89.14 



92.08 
91.48 



3.3 

2.2 



.->. 4 
3. 2 



94. 72 1 . > 
.SO. 43 1.1 



.11.-, \7. 77 3.6 
06 i.'< 

'..7.23 : 



2 1 






U lo I 



(') 



5. 9 
3. \ 



1 

2.8 



2.8 
2.0 



1. 1 
2.8 



3.0 
l.i, 
3.0 



Light oils 
up to 
110° C. 



B0. 3 

.4 
1.9 
1.4 

1.0 



'2.8 

2.6 



1.7 

2.4 



- 1. 1 
2.9 

» 1.4 

1 

3. 1 

9 1.6 
1.3 
1.1 

1. 1 



9 1.7 

» 1.3 



I s 



'".5 



0.3 
.3 
1.5 
1.2 
1.3 



2. :< 
2.1 



1.0 

2.3 



1.2 



Middle Heavy 

oils, 110°-! oils, 170°- 

170° C. 270° C. 



5| 



0.8 
"2.0 

.7 



9.4 

.6 



... 
.6 
1.4 



9.2 

".4 



9.3 



tlUate, two-third "lid 
u in tlllate, four-fifth olid. 

n-ii'ii olid. 
•,11 ii.-. one-ninth no lid. 
: illate, "Hi- third "lid 

■ !<d. 

tie, "ii>- fifth "hd. 



"13. 1 

9 14.0 

14.9 

"21.1 

ii 17.:. 

is 23. 6 

u 14.6 
io 17.6 

16 20.0 

18.6 



is 



Heavy 

oils, 270°- 

315° C. 



22.8 19.5i» 13.6 
i- 16.5 II. 1 i«9.3 



.6 .5 23.5 20.4" 15.6 



11.5 
12.3 

13.2 
18.9 
15.5 

20.7 



19 8.2 

■»7.9 

a 11.9 

»5.5 

1*9.4 



7.3 

'.. 9 



rial 
No. 



a. 3 



»76.6 
5*74.7 
10. 6 » 69. 5 

4. 9]^ 69. 4 
8. 4* 70. 1 



9 9.8, 8. 9 "65.1 



13.0 «6.9| 5.7|26 68.4 
••a 11. 4 



1.-,.:. 
17.8 
16.3 



21 6. 5 

107.0 



. 1" 13.0 10.9 



.6 .:, 27.2 



27. 'I 

i« 12. 1 

1- 17. 2 

23. (I 

1-21,. It 

"IS. 1 

9 20.0 
»20.6 

i«20.. r 



24.2 

24.4 

10.2 
15. 1 

21.4 

23.6 



18.0 

is.; 



•-1 9. 4 

197.3 
193.8 

19 11.0 

21 9. 6 
10 11.6 



19 12.5 

11 13.4 
9 7.1 



10. 4 » 63. 8 
:.,: - 69.6 

6.S- 6S.0 



12. 5 

8.2 
14.4 

8.1 
6.7 

3.5 

9.7 
8.5 
10.4 

6.3 



12.0 
6.5 



57.8 

27 69.3 
-• 55. 2 

70 
"59.8 

»61.1 

»73. 
» 69. 7 
"60.8 

"63., 



Ph 



79.1 512S 

77.6 5123 
73. i 5124 

72..". .'.137 

73.7 5121 

68. 9 J 5125 

72. 0| 5128 

67.7 5200 

73.1 5189 

71.5 5160 

62.6 5074 

73. 2j 5081 

59.7 5095 

74.6 5083 

63 5 5159 



2« 62. 8 
28 67. 1 



64. 

77.5 
73. 2 
64 

67.6 
67.8 

66. 3 

70.2 



6.9" 72.0 74. S 



.-.107 

5086 
5078 
5087 

5109 



5188 
5404 



5108 



..127 



-' 11. s 10. 2-' 71. 1 75. 50K9 



a Distillate, two-fifths Bolid 
« Distillate, one-seventh solid. 
LIUate, throe I 

iini tlcky. 
m Pitch, toi 5 Bofi and Btlcky. 
■ Pitch, hard and brittle 
» Pitch, pis itlo, 



8 COKE-OVEN TARS OF THE UNITED STATES. 

interior of the coal block, with the fire-resisting gases escaping at the 
same time from the outer zone of the block. On the other hand, in 
the case of gas retorts, the heavy vapors escape at once undiluted 
by the fire-resisting gases which are set free afterwards, and the 
heavy gases are thus exposed to the white heat of the upper part of 
the retort. " 

Answers given by the manufacturers with respect to this question 
indicate only an approximate knowledge. In general it may be said 
that carbonization below 970° 0. is considered low temperature; from 
970° 0. to 1,100° C, medium temperature; and from 1,100° C. to 
1,540° C. high temperature; and that modern gas-house practice 
involves the use of high temperatures. However this may be, it is 
not the purpose of this circular to compare coke-oven tars with gas- 
house tars, but to consider the former with relation to their utility 
as road materials. 

From a total of 31 manufacturers to whom the questions were sub- 
mitted 30 replies were received, but 4 of these reported their plants 
as not in operation. The remaining 26 furnished samples of their 
crude tar for examination and answered the questions in so far as 
they were able. Upon receipt of each sample the entire contents of 
the package were thoroughly mixed and a representative sample 
taken for analysis. The results of these analyses, together with the 
information furnished by the manufacturers, are given in Table I. 
In this table the different tars are grouped according to the type of 
oven in which they were produced. 

In columns 4 and 5 all temperatures are expressed in degrees 
Centigrade, although where the manufacturers gave the temperatures 
in degrees Fahrenheit their statements are shown in parentheses. 
In column 5 it will be noticed that statements relative to the maxi- 
mum temperature to which the coal is brought during distillation 
indicate that two of the plants run below 970° C, that a total of 
22 run not over 1,150° C, that 9 run 'from 950° C. to 1,150° C, and 
that only 5 run above 1,150° C. The maximum temperature of 
firing the retorts is, however, reported in most cases as being higher 
than the maximum temperature to which the coal is brought. 

The maximum percentage of free carbon reported is from 16 to 24 
per cent, but 17 manufacturers reported the maximum percentage of 
free carbon as being 12 per cent or under, and only 4 as 16 per cent 
or over. 

Analyses of the samples received were made in accordance with the 
methods described in a former publication x of the office. The work 
consisted in determining the specific gravity, free carbon, or organic 
matter insoluble in c. p. carbon disulphide upon a 15-minute digestion 
at room temperature, material soluble in carbon disulphide, percent- 
age of ash, and percentage of different fractions obtained by distilling 
a 250 c. c. sample in a 750 c. c. tubulated glass retort with the ther- 

1 Bulletin 38, Office of Public Roads, U. S. Department of Agriculture. 



COKE-OVEX TABS OF THE UNITED STATES. 



9 



mometer so placed that the top of the bulb was level with the bottom 
of the juncture of the stem and body of the retort. 

It will bo noted that the gravities of the samples examined range 
from 1.133 to 1.214 and that the great majority are lower than 1.200. 
This in itself indicates low percentages of free carbon. The mini- 
mum percentage of free carbon was 2.73, the maximum 16.80, and the 
average for the 20 samples 8.38. Eighteen samples contained less 
than 10 per cent of free carbon and 8 more than 10 per cent. About 
two-tbirds of these products might, therefore, be considered as low- 
carbon tars and the otner third as medium-carbon tars. The amount 
of ash in no case exceeded 0.16 per cent, and in most cases it was 
practically nil. This is, of course, also true of practically all gas- 
house coal tars. The percentage oi water present varied from a 
trace to 10.1 per cent by volume, but in only 3 instances did it exceed 
5 per cent. Water is a variable, depending upon a number of condi- 
tions, and, as it is not a pail of the true tar, has been eliminated 
in Table II. Before leaving Table I, however, it is of interest to note 
that 14 of the pitch residues, remaining after distillation had been 
carried to 315° ('., were either soft or plastic — a condition which has 
seldom been noticed by the author in the distillation of gas-house 
eoal tars. The amount of solids which crystallized or precipitated 
out of the different fractions was found to vary greatly, as shown 
in i he foot-notes to Table I. 

Table II. Analysis of coke-oven tars upon a mater-free basis. 





Type of oven. 


Percent- 
age of 

free car- 
bon. 


Fractions 1>> weigh I. 


num- 
ber. 


Percent- 
age up 
toll0°C 


Percent- 
age from 
1 10-1 70° C. 


Percent- 
age from 


Percent- 
age from 
270-315°C. 


Percent- 
age of 

pitch. 


51 20 
5123 


Semet-Sol v:i\ : 

do 


7.82 

8.84 
7.21 
6.19 
4.73 
7.49 
6.97 

9.00 
5. 19 
4.04 
7.09 
14.22 

11.12 

8. 02 

8.60 

[o.ea 

12.56 
3.96 
2.81 

11.51 

ia 62 

17. 17 


0.30 

.30 

1. 55 

1.21 

1.30 

.30 

2.44 

2. 1 " 

1.42 

1.95 

1.32 

1.02 

2. 34 

1.40 

1 . .VI 

2.57 

1.2! 

.91 

.91 

.'HI 

1 . 34 
1.21 
1.03 
1.43 

2, 50 
.3«> 


0.70 
1.71 
.00 
.00 
.00 
.90 
.31 
.51 
.20 
. 30 
.81 
.-'ii 
.51 

. 10 

.51 

.01 

.-in 
.-ii) 

1.31 
. HI 
M0 
.20 
.30 
.50 
23 

L73 


11.59 
12. 39 
13.33 
19.18 
15. 57 
20. 70 
13.81 
tl hi 
18. in 
16.76 
19.89 
14.50 
20, si 
11.40 
24. 89 
25. 15 
L0.30 
16.29 
21 63 
23. 83 
16.89 
18 29 
19.07 
18.66 
6. 66 

10. 12 


7.35 
0.95 

10.70 
1. 97 
8.44 
8.90 
B 06 

10.76 
5.79 
6,99 

1 2. 75 
8. 13 

i i 69 
V47 

8.60 

9.79 

8.1,1 

10.51 
6.86 

11.41 

12 19 

7.M 


79. 73 
7s. 22 


5-24 


...do 




5137 


...do 


73. 60 


5121 


do 


74.07 


51 -'.5 


do 




5128 


...do 


76. a 


5200 
5180 


do 

do 


70. 08 
74.36 


5100 


do 


73. 55 


.5074 


.do 


1 :■;. B7 




.do 


75.30 


5095 








do. 


78.08 




do 


66. 32 


.",107 


do 


66. 90 




MM., 


78. 28 




do 


71. 16 


5087 


...do 


65. n 


5100 


do. 






do 


69. 89 






67.87 






72. 37 


5127 


Otto Hodman and United Otto 

do 


71. r, 
81.67 


5088 


i nlted Otto and Rothber] 





The results given m Table II arc calculated upon a water-free 

basfe i.e., the percentages are expressed in terms of the actual tar 

exclusive of water. Considering these products according to type, 



10 



COKE-OVEN TABS OF THE UNITED STATES. 



it will be seen that the tar produced by the Koppers ovens contains 
the lowest percentage of free carbon, the Semet-Solvay tars the 
next lowest, the United Otto next, the Otto Hoffman next, and 
the mixed tar from the United Otto and Rothberg ovens contains 
the highest percentage of free carbon. For the sake of comparison 
the minimum, maximum, and average percentages of free carbon 
for eiich of these types are shown in Table III. 

Table III. — Percentage of free carbon in coke-oven tars. 
(Water-free basis.] 



Type of oven. 



Percentage of free carbon. 



Minimum. Maximum. Average 



Koppers 

Semet-Solvay 

United Otto 

Otto Hoffman 

Otto Hoffman and United Otto (mixed) 
United Otto and Rothberg (mixed). . .. 



2.81 
4.04 
5.20 
8. 02 
11.51 
17.17 



3.95 
9.00 
12.55 
14.09 
13.52 
17.17 



3.38 
6.74 
9.00 
12.10 
12.51 
17.17 



The percentages of various fractions for the different types of 
tars overlap to such an extent that no detailed comparison will 
be made. The maximum, minimum, and average total distillates 
to 315° C. for the different types are, however, given in Table IV. 

Table IV. — Percentage by volume of total distillate to 315° C. in coke-oven tars. 

[Water-free basis.] 



Type of oven. 



Percentage by volume. 



Minimum. Maximum. Average 



(Coppers 

Semet-Solvay 

United Otto 

Otto Hoffman 

Otto Hoffman and United Otto (mixed) 
United Otto and Rothberg (mixed) .... 



30.5 
22.0 
25.0 
25. 3 
19.9 
26. 9 



30.0 
40.8 
38.5 
43.0 
32.1 
20.9 



33.3 
29.9 
32.6 
30.0 
20. 
20.9 



From this Table it is evident that wide variations exist in the 
relation of total distillate to pitch residue in the coke-oven tars 
produced in this country, and this is even true of different tars 
produced by the same type of oven. 

Straight coal-tar road binders or refined coal tars are usually 
manufactured by subjecting the crude material to a process of dis- 
tillation with or without steam or air agitation. Distillation is 
carried to the point at which the residuum remaining in the still has 
obtained the desired consistency at normal temperatures, and this 
involves the removal of certain of the more volatile oils present in 
the crude material. For use in construction work a soft and almost 
fluid pitch is often produced, and the consistency of this pitch is 



COKE-OVEN TABS OF THE UNITED STATES. 11 

controlled by means of a melting point or float test. When the 
crude tar runs abnormally high in free carbon, it is sometimes mixed 
with crude water-gas tar before distillation. Water-gas tar con- 
tains a very low percentage of free carbon, and by properly propor- 
tioning the two a product is obtained, upon distillation, which 
does not carry more than the maximum limit of free carbon set by 
manufacturers. What the maximum limit should be is a much 
mooted question among those who have given thought to this mat- 
ter. The governing considerations are: (1) What is the most econom- 
ical limit from the standpoint of manufacture? and (2) What is 
the proper limit with regard to the utilization of the product as a 
road material? For a number of reasons, which it is unnecessary 
to mention in this circular, an excessively high-carbon tar is difficult 
to distill properly and, with other things equal, the lower the per- 
centage of carbon the easier and shorter the distilling process. From 
this standpoint, therefore, by-product coke-oven tars are well adapted 
to the manufacture 1 of road binders. Moreover, because of their 
low percentage of free carbon, they may be employed in a manner 
similar to water-gas tars, when it is desired to utilize a crude high- 
carbon tar in the production of a medium-carbon tar road binder. 

In an ordinary road tar for use in construction work where free 
carbon is present to the extent of about 20 per cent, the proportion 
of total distillate, below 315° C, to pitch residue is approximately 
1 to 4. Where this relation exists the pitch residue is hard and 
brittle. A residue which is soft or plastic is to be preferred, as 
it would indicate longer life during service, and where such a residue 
is present the proportion of distillate would naturally be lower 
for a given consistency, as the distillates may be considered as 
fluxes for the residues. If such is the case, it is evident from the 
foregoing tables that coke-oven tars oiler a valuable source of supply 
for tar road binders. As an example, even the highest -carbon 
tar, No. 5089, if distilled to the point where the proportion of dis- 
tillate, below 315 <'., to the pitch residue was as 1 to 4, would con- 
tain less than l'.t per cent of free carhoii. which is at present con- 
sidered as not excessive for a refined coal tar. 

In conclusion it may he said that indications point strongly to 
the fact that by-product coke ovens will eventually play a most 
important part in the road-mat dial industry, and it is to be hoped 
that their general adoption in this country will be rapid. The 
future demand for economical bituminous road hinders in the I oited 
States will undoubtedly exceed the supply, and this in spile of the 
natural increase in petroleum and asphalt road binders. If such 
is the case, the present loss of enormous quantities of tar. to sa\ 

Dothing of gas and ammonia, because of the use of beehive ovens, 

is a matter Worth) of the utmost consideration oil the part of all 
who arc interested in the conservation of our resources. 

o 



UC SOUTHERN REGIONAL LIBRARY FACILITY 

I I llll I I 



AA OOO 731 026