Coal bitumens

COAL BITUMENS (EN: coal bitumen; DE: Kohlenbitumen; FR: bitumes à charbon; ES: bitumenes de cardon; RU: битумы угольные) are the products, which are extracted from the certain types of the mineral coals by the organic solvents, namely, by the mixture of the saponifiable substances, free acids, their anhydrides and hydrocarbons. The yield of the coal bitumens depends on the nature of the organic substance, its composition, degree of metamorphism, conditions of extraction, and ranges within the 1-22% limits; it decreases with the increase of the degree of coalification. The highest yield of the coal bitumens is characteristic for the humite-liptobiolite ones, and also for the gelificated humic slightly metamorphosed brown coals of the B1 group. Within the coal bitumens, which are extracted from the brown coals at the atmospheric pressure, and at the temperature, which is not exceeding the temperature of the boiling point for the solvent (benzene, dichloroethane, gasoline, and others), they conventionally distinguish the waxy and tarry parts.

There has the major practical value the waxy part, which is the raw material for the obtainment of the lignite wax, which is also named as the "montan wax". The source of the waxes within the coal bitumens is the lipoid components (tars, waxes, cutin, suberin, fats) of the wax-tar-containing angiospermous and coniferous plants. The coal bitumens, which are extracted from the black coals and dense lustrous brown coals, do not contain wax. They limitedly use the tars, which have been extracted, as the softeners during the production of the varnishes, rubbers, and plastics, and as the substitutes for phenols during the production of the varnishes, glues, and tannins.