What is coal tar made of



  Coal tar is a product of coke production. The viscous black mass, which gives off an unpleasant odor, is obtained from the gases produced in the coking plant.

use

Coal tar is used, among other things, as a wood preservative (e.g. for railway sleepers) and for roofing felt. It is or was the starting material for the production of various chemical substances, including tar dyes and carbolineum

Phenols are still largely obtained from coal tar today.

Purified coal tar extracts can be used in the treatment of psoriasis (e.g. Psoriasis vulgaris) and chronic eczema, but are banned in Germany as an ingredient in cosmetics due to their carcinogenic properties. Coal tar inhibits itching (antipruriginous) and has a bactericidal, fungicidal and insecticidal effect (due to its ingredients, e.g. the cresols).

hazards

Coal tar contains a wide variety of substances, some of which are toxic, harmful to the environment or carcinogenic (carcinogenic). For these reasons, the use is nowadays severely restricted (tar oil regulation).

Manufacturing

If hard coal is heated to 650 to 800 ° C in closed vessels with the exclusion of air, the coal decomposes into the following products:

Coal tar is nowadays obtained as a by-product of coking. Coke is extremely important for iron smelting.

Coal tar consists of several thousand aromatic compounds, including hydrocarbons, nitrogenous bases and phenols.

Naphthalene, anthracene, pyridine, quinoline and pyrene are obtained in large quantities from coal tar; it was also an important raw material for road construction (see tar). The tar has only been used industrially since the middle to the end of the 20th century and was previously buried as waste next to the coking plants.

The Separation takes place mainly through fractional distillation or crystallization, thereby being 5 factions separately (starting with lowest temperature (benzene) to highest temperature (anthracene)):

About 50% of the tar used is obtained as pitch (tar pitch), which was originally mainly used in road construction. Today pitch is the main product and is mainly used as a binder for anodes in aluminum production.

See also

bitumen

Web links

  • De-taring using the example of the Vienna-Simmering gasworks

Categories: Mixture of substances | Drug