Coal Tar, It’s derivatives and their uses

 

Crude Coal Tar is obtained by the ‘Destructive Distillation’ of coal, in which coal is subjected to heat in a ‘Retort’( A type of enclosed furnace ) in the absence of oxygen. The product of this process is Coke, Coal Gas, and Coal Tar. In the 1940s, the annual production of crude Coal Tar was near three million tons, practically all of which is distilled to obtain more refined products. Coal Tar is an extremely complex chemical, a mixture of Hydrocarbons, Phenols, Oxygen, Sulphur, Etc. ranging from simple compounds like Benzene and Phenol to very complex materials with high molecular weights which cannot be distilled even under a high vacuum.

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The chemicals derived from coal tar, hence from coal, are very numerous, from things like Saccharine to Explosives. This list includes Wood preservatives, Paints, Dyestuffs, Disinfectants, Pharmaceuticals, Terylene, Weedkillers, Benzole, Nylon, Aniline, Motor fuels, Alkyd and Polyester Resins, Resins for flooring tiles, Anti-corrosion chemicals, Naphthalene, Creosotes, Etc. to name but a few, and some of which can be further sub-divided into other equally important chemicals.

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Fractionating is carried out in a similar manner to Crude Oil, petroleum, Etc. in a ‘Fractionating Column’ when the lighter ‘Fractions’ leave the tower at higher levels. These were originally known as ‘Continuous Pipe Stills’, and were first used in the tar industry in the 1890s, and have been subsequently adopted by the Petroleum industry.

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One of the most important is Ammoniacal Liquor, from which is made Ammonia, the source of such diverse chemicals as Ammonium Nitrate, which is both Fertilizer and a constituent of many explosives, besides being – under the correct conditions – a powerful explosive in its own right, as has been demonstrated many times by various groups!

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There are also several important liquid fuels distilled from Coal Tar, these are:

C.T.F. 50. C.T.F. 100. C.T.F. 200,250, & 300, from which also come Road Metal Binders, C.T.F. 300. & C.T.F. 400.

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Coal tar is, as we have stated, a mixture of a great number of chemically distinct substances, which prompts a chilling thought: in 1915, two Japanese experimenters showed that cancer could be induced by painting the skin of animals with coal tar.