IMPROVEMENTS IN AND RELATING TO THE EXTRACTION OF MATERIALS

1,261,707. Extracting carbonaceous materials. COAL INDUSTRY (PATENTS) Ltd. 17 June, 1969 [21 June, 1968], No. 29744/68. Heading C5E. A method of extracting at least part of the carbonaceous content of a carbonaceous material, e.g. coal, coal tar, anthracene paste, or naphthalene base oil, comprises treating the material with an extractant fluid at a pressure and at a temperature above the critical pressure and temperature of the fluid, and subsequently reducing the pressure to separate the extracted part from the fluid. Extractants referred to are methane, ethane, propane, ethylene, propylene, ammonia, chlorine, carbon dioxide, benzene, toluene, pyridine, and ethyl- and (di)methylamine. Specific examples are the de-ashing of coal with benzene, extracting coal tar with ethylene to recover oils and pitch, and extracting pitch and anthracene paste with ethylene. In this last example anthracene and naphthalene are recovered. The method may be combined with a coal carbonization process, e.g. in a fluidized bed of coal to which the extractant is delivered, carbonization products being carried off by the extracfant. In all the examples, the separated extractant, after recompression, is recycled.