DISSOLUTION OF COALS NEAR-CRITICAL CONDITIONS

Two lignites and one bituminous coal were extracted with benzene, tolu ene and pyridine at both sub and overcritical conditions in a speciall y designed experimental system which enabled easy solid-liquid separat ion. Extract yields increased somewhat at overcritical conditions due to more thermal decomposition. The differences between the power of th e solvents were not apparent for the lignites, whereas the solubility in pyridine of the bituminous coal was very much higher than those in benzene and toluene. The amounts of oils, asphaltenes and preasphalten es in the extracts depended on the type of coal and the solvent.