.July, 1!U5
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INDUSTRIAL A N D ENGINEERING CHEMISTRY
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The Coking and Swelling Constituents of Coal' By Franz Fischers Kmsaa \VI'~.HILM INSTITUIPUR KOXLGNIIOESCIIIING, MI)I.L~L(Iu. Ruaa. G Q R M A N Y
Extraction of coal with benzene a t 250' C. yields an extract which can be divided into two main components by means of petroleum ether-one soluble in gasoline, the other a solid brown, insoluble body. Recently it has been discovered t h a t the oily body is the principal source of the coking quality of the coal and apparently consists only of hydrocarbons. In contrast to this, the solid body, which is decomposed by heat with gas evolution, has been shown to be the principal cause of the swelling of coal; it consists of compounds containing oxygen. Theoily body has been named "oily bitumen," the solid body, "solid bitumen;" the sum of the two "total bitumen." The older the coal the larger percentage of oily bitumen it contains. The quantity of total bitumen, however, decreases considerably with the older coals.
The decomposition point of the solid bitumen rises with the age of the coal; it is of more significance in causinq swelling than the quantity of solid bitumen. If it lies a t the temperature a t which the coal is plastic then the swelling is greatest. With the oily bitumen, on the other hand, its quantity is of greatest significance. With repeated successive extraction of strongly swelling coal the swelling property first disappears, but the coal still remains coking; finally the ability to coke is also lost. If the totdl extract is again added to the extracted coal the original coking properties of the coal return. If the oily bitumen only is added, then nonswellingcoking coal results. If the solid bitumen only is added, poorly coking but strongly swelling coals result.
S THIS investigation use was made of a continuous es of coals increasing in geological age from the lioncoking coals to blie geologically oldest, anthracite. The cowls were obtained from t.he Ruhr, Saar, and Upper Silesian c i m l bed.-. The nonsintering tspe investigated was the U p per Silcriaii, Lipine coal; of the semi-sintering coals the I)ilshurg coal from the Saar was used; of the caking sintering roals, the Iahherg coal from ilie Ruhr and tile itltenwald r o d from tlie Saw; of t,he caking and swelling coals the Pmslx.',r, tlie Osterfeld, and the Fritz Thyasen coals from the Ilulir. Before t,l~esecaals were niibrriitted t.o extraction, witli h~nzeneat high t,emper;itiirrs, it was necrssaly to det.ertnitie a t what point. they began to decompose. The temperatore of the first deoornporition is the limit which in the labcr extra
