Jan., 1913
T H E J O U R i V A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
goods, and very careful experiments have demonstrated the fact that the insoluble tin compound in the fibre has not the slightest deleterious action on the most delicate skin. I n addition, the presence of the tin compound in the pores gives the cloth a softer and fuller feel than that of the original flannelette and what perhaps is the most unexpected result is the fact that the material is considerably strengthened by the process. A series of tests made by the Manchester Chamber of Commerce proved that the tensile strength of flannelette is increased nearly 20 per cent. as the result of the introduction of the tin compound into the fibre. Further and very exhaustive tests made a t the Municipal School of Technology, Manchester, on a machine specially designed for testing the wearing properties of fabrics, showed a n even greater gain in durability in the case of the fireproofed flannelette. These separate and independent tests conclusively showed that the increase in strength and durability was approximately equal to the cost of the fireproofing treatment so that garments made from the permanently fireproofed flannelette are as a matter of fact no dearer than those made from ordinary flannelette and are, a t the same time, as safe as if made from flannel. Some of these properties and statements may be easily tested by each of you independently with the samples in the little book which you received on entering the Hall. This permanently fireproofed flannelette is now manufactured on the large scale by Messrs. Whipp Bros. and Tod in Manchester under the name of “Non-Flam” and, although its introduction has been slow, i t is being increasingly used and will, in all probability, ultimately entirely replace the ordinary inflammable variety. One of the difficulties experienced in connection with its general introduction is the fact, that, owing to the high price of tin, which is now quoted a t about A210or $1050 per ton, the cost of the process is not inconsiderable but, even with tin at this high price, the extra cost is not more than two cents per yard or about three or four cents for a child’s garment. I have here on the table rolls of “Non-Flam” of different qualities so that any one who wishes for a larger sample than is contained in the little book can easily obtain it. I t is hardly necessary for me to say that this process can be applied to any cotton fabric and is especially valuable in connection with muslin because this material is so often used, especially on the stage, for dresses which, on account of their flimsy nature, are naturally highly inflammable. I have here two strips of the same muslin, one of which has been treated by the “Non-F1am”process without in any may affecting its ordinary properties and was then washed I O times and the difference in inflammability of the two samples is very striking. While the first sample is highly dangerous, it is difficult to imagine that harm could come to any one who happened to be dressed in the treated material even if, by accident, a lighted match came in contact with the dress. Another direction in which the process may be used with great advantage is in connection with lace curtains. Many disastrous fires have occurred by reason of the ignition of lace curtains and there can be no doubt that the greater majority of these would have been avoided if the curtains had been treated by the “Non-Flam” process. As a n example of this, I have here a strip of lace curtain which has been subjected to the process and then washed a number of times, and it will be seen that if such material did accidentally come in contact with a lighted match, the danger of fire is reduced to a minimum because even supposing the material did catch fire, the flame is put out a t once by the least shake. I t seems to me that it is obvious that, if this process or some other process capable of giving the same protection from fire, were adopted in the case of all inflammable cotton goods and especially in the case of material used for garments, many disastrous fires and the appalling loss of life, especially among young children, might be avoided, and it is for this reason that I have
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ventured to bring the subject of the permanent fireproofing of cotton goods to your notice this afternoon.
COAL TAR LIGHT OIL IN THE UNITED STATES: THE MANUFACTURE, NATURE AND USES OF PRODUCTS DERIVED THEREFROMI
By
JOHN MORRIS WEISS
Introductory.-This paper is a n attempt to give a rather general outline of that part of coal tar refining dealing with the lighter oils obtained in the first distillation of coal tar. The writer has taken as his theme the so-called “coal tar light oil,” and has, in the general description, written as if this were the only source of the refined products mentioned. I t must not be forgotten that other products are used as raw materials for the same purposes, and are mixed with light oil products a t various stages of manufacture. Thus, coal tar carbolic oil, water gas tar light oil, crude benzol from washing coke oven gases, and Pintsch gas drips may serve as raw materials to be introduced a t some point or other in the manufacturing processes. The figures given for production include products from all these sources, and are not confined to light oil products alone. The figures are the result of compiling as much information as the writer was able to obtain from various manufacturers. Light Oil Production.-Light oil is produced in the first distillation of coal tar, being the first fraction of oil taken off. I n practice, it usually consists of that portion of oil collected while the water is being removed. The amount of light oil obtained from different tars varies considerably, some containing only a trace, while in others i t may run as high as 4 per cent. A fair average for coal tars distilled in the United States is about z per cent. Nature of the Materid-Light oil of coal tar, as produced in the United States, varies in composition, depending on the nature of the tar from which it is produced, and upon the method of distillation used. In all coal tar light oil we meet with the same constituents, but their proportions can vary quite widely. The main constituents of coal tar light oil can be roughly grouped into four classes: I . Neutral hydrocarbons of the aromatic series. 2 . Unsaturated hydrocarbons of various series, the main one, however, being of the styrolene type. 3. Basic bodies, consisting of pyridine and the higher homologues. 4. Acid bodies known as “tar acids,” here consisting of phenol and the three isomeric cresols, with small amounts of their higher homologues. Besides bodies falling into these classes, there are small amounts of other materials such as carbon bisulfide, various organic nitriles and various sulfur compounds, such as thiophene, etc. All the materials manufactured from light oil in the United States fall in the first and fourth classes mentioned above. Methods of Testing Light Oil.-The assay of light oil usually consists in: I . A distillation, which gives the approximate amount of hydrocarbons boiling at various temperatures. 2. Determination of tar acids. 3 . Determination of tar bases. 4. Determination of naphthalene. 5 . Determination of specific gravity. These tests, with the exception of that for tar bases, have been described in detail, with drawings of the apparatus used, by Mr. S. R. Church (THIS JOURNAL, 3, April, 1911). The tar base test is carried out in exactly the same manner as the test for tar acids, preceding this in the analytical process, with the exception that z o o B. sulfuric acid replaces the I O per cent. soda used in the corresponding tar acid test. 1 Paper presented at the Eighth International Congress of Applied Chemistry, New York. September, 1912.
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T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
I n exceptional cases more exhaustive tests are made, which include a very careful fractionation of the light oil neutral hydrocarbons, to determine the approximate percentage of pure benzene and toluene, etc., but as these are b u t seldom used, it seems well to omit them here. As a means of showing how widely light oil from various sources can vary, the following tests are given as representing average coal tar light oil produced in the United States: Maximum Minimum Specific gravity.. ..................... Tar acids.. ........................... Naphthalene. ......................... Hydrocarbons boiling below 200’ C..
....
1.002 18 .O% 29 . 9 r 0 62.0%
0.953
4.0T0
trace 30.0’?’0
Average 0.985
7.57’0 13.2% 48.0%
These tests do not include the determination of tar bases, as this is seldom made. I may say, however, that the bases amount to b u t one to three per cent. of the light oil. First Distillation of Light Oil.-This is carried on in iron horizontal cylindrical stills, with a capacity of from 3000 to 5000 gallons, in sizes varying from six to eight feet in diameter, and fourteen to sixteen feet in length. The stills are set in brick work with either oil or coal firing. The type of setting has changed from time to time, the most approved type a t present being that with a firebrick arch, the hot gases of combustion passing under the arch to the back and then over it under the still to the stack at the front. The stills are provided a t the top with a vapor pipe, a n opening for charging and a man-hole for cleaning, a t the bottom with a draw-off for removal of the residue. The vapor pipe runs directly to the condenser without any baffling or fractioning device intervening. A thermometer set in the vapor pipe of the still serves to regulate the fractions taken off. The distillate is run directly from the condenser into tanks or pans, depending on its nature. I n this first distillation, the light oil is split into but two fractions, one, crude naphtha, up to about Z O Q O C., taken off into a storage tank, and above that point, naphthalene oil, which is run directly into large, shallow iron pans. The residue in the still is thick, and is run out when cool and mixed with crude tar. The heavier fraction, containing naphthalene, is allowed to cool to air temperature, when the naphthalene settles out. As much oil as possible is drained off by gravity, and the drained naphthalene centrifugaled to further remove oil. These separated crystals form crude naphthalene, the working up of which will be described later. The oil drained from the naphthalene is moderate boiling creosote, containing a high percentage of tar acids, almost entirely cresols and the next higher homologues. This oil is used as the basis of “percentage” carbolic acids second quality, a s described later, or is artificially frozen to further remove naphthalene, and the frozen, well settled oil, containing about 25 per cent. of tar acids, is used for the manufacture of disinfectants and sheep dips, or as a basis for first quality “percentage” carbolic acids. Treatment of Crude Naphtha.-The crude naphtha is first brought into iron cone-bottom agitators of about 12,000 gallons capacity, and the tar acids removed b y treatment with dilute caustic soda solution. This solution of tar acids (mainly phenol and cresols) serves as the raw material for the manufacture of the refined grades of carbolic acid, as mTill be described in a later part of this paper. The naphtha freed from tar acids is then treated in lead-lined agitators with sufficient dilute sulfuric acid to remove basic bodies. At present, owing to the fact that the market for pyridine bases is very limited in the United States, no attempt is made to recover these bases, but the pyridine sulfate liquor is thrown away. The extracted naphtha is then subjected to fractional distillation under vacuum of about z g inches, using a column. This is carried out in stills of the same size and type as used in the first distillation, a column and reflux condenser being used between the still and the condenser. The fractions are collected of necessity in closed receivers. This distillation is regulated,
Jan., 1913
like the other, by a thermometer in the vapor pipe. Four fractions are taken off: I . Crude benzol and toluol fraction. 2. Intermediate fraction to be re-run. 3. Crude solvent naphtha fraction. 4. Heavy naphtha fraction. The residue left in the still is re-run in the crude straight pipe stills as described in the first distillation of light oil. The crude benzol and toluol fraction is re-run in a vertical still with a steam coil and column, and separated into: IA. Crude benzol. IB. Intermediate fraction to be re-run. IC. Crude toluol. All is gradually accumulated into fractions IA, IC, 3 and 4, which come into commerce as “straw color benzol,” “straw color toluol,” “crude solvent naphtha,” and “heavy naphtha.” Refined Benzols fro yn Crude Fractions.-The crude fraction is placed in a n iron cone-bottom agitator provided with a mechanical stirring device of the propeller type, and there treated with sulfuric acid, the amount varying with the nature of the material. The sulfuric acid polymerizes and removes in the form of tar the unsaturated hydrocarbons, leaving the aromatic hydrocarbons practically untouched. After the sulfuric acid treatment, the acid is carefully drawn off, together with any tarry matter which collects immediately above the acid. The acid treatment is followed by a treatment with dilute caustic soda to remove small amounts of acid left on the sides of the agitator and mixed through the oil. I t is then run to a vertical still, provided with steam coil and live steam. In the case of the lower boiling materials, crude benzol and toluol, the distillation can be carried on almost entirely without live steam, but with the higher boiling materials live steam is necessary to complete the distillation. The product of this distillation is refined go per cent. benzol, from the crude benzol fraction, commercial toluol from the toluol fraction, refined solvent naphtha from the crude solvent naphtha fraction, and zooo naphtha from the heavy naphtha fraction. Fifty per cent. benzol and IOO per cent. benzol are made in a similar way by altering as necessary the distilling points on the crude column distillation of fraction No. I , as denoted above. The 50, 90 and 100 per cent. benzols consist mainly of benzene and toluene, with small amounts of xylene, and their names are not indicative of the comparative purity of the materials, but merely of the amount distilling a t I O O O C. The lower boiling benzols can have the following composition: l O O y o Benzol 90% Benzol 50% Benzol
Benzene ........................ Toluene. . . . . . . . . . . . . . . . . . Xylene . . . . . . . . . . . . . . . . . .
94-97ojo 2-670
80-85% 10-20%
4040% 30--60%
0-5 7% o-zs7‘o Pure Hydrocarbons.-The manufacture of these consists in taking a refined fraction, such as obtained from the process described in the preceding paragraphs, and submitting it to column distillation in a steam still with a .very high column, and taking off a fraction within very narrow temperature limits. Only benzol (benzene) and toluol (toluene) are separated in the pure condition, that is, with less than 0.5 per cent. of impurities. A substance called “pure xylol” is manufactured, consisting of a mixture of the three isomeric xylenes. N o attempt is made in this country to separate the three isomers. Pure benzol has about the following composition:
Benzene. . . . . . . . . . . . . . . . . . . . . . . . . . . Toluene.. . . . . . . . . . . . . . . . . . . . . . . . . . .
...................... .............
Carbon bisulfide.
99.5-99.87’0 0 .OS% 0-0.10% 0-0.02%
Testing of Benzols.--For a description of the various tests used on benzols, that is, boiling point, specific gravity, flash,
Jan., 1 9 1 3
T H E JOC-RAY.4L OF I - V D C S T R I A L ALVD ESGI.\-EERISG
e8
CHEMISTRY ~
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I n straight pigment paints, benzol has not found wide applicaevaporation test, freezing point, and sulfuric acid test, the tion as yet, but it has been found of considerable advantage as a author has already published these (THISJOURKAL, 3, IO, thinner in paints designed for painting resinous woods, owing to (191I)), and therefore it does not seem necessary to go into these the penetration or “tooth” given to the paint. This use has in detail here. been very well described in a paper by J. Dewar, published in Profierties of Benzols.-These can best be given in tabular the Proceedings of the Convention of Master House Painters form, and we present here the average distillation tests, specific and Decorators Association of Pennsylvania, January, 191I , gravity, flash, evaporation, sulfuric acid tests, etc., of the refined grades of benzol, and the distillation, specific gravity, printed in the Painters’ ,\4agazine for Xarch, 1911. Enamel paints, as well as bronze and aluminum paints, also flash and evaporation tests of the crude benzols: afford a use for benzol. These paints usually have a concenBOILIXG SP. GR. AT FLASHEVAPORATION 15.5’ C. POIST TEST POINT PRODUCT trated solution of Damar gum as their base, and benzol is an 0.881-0.884 Beloiv O ’ C . 10 min. 80-82’ C. Pure benzol’ ideal material for this purpose, owing to its very strong solvent 131,’~ l00Ci; a t 100” C. 0.875-0.884 Below O 3 C. 100% benzol action on this gum. 0 875-0.882 Below O 3 C. 14 90% benzol 90
