The influence of extraction with organic solvents on coking properties of raw and reduced coals

The dilatometric properties and Roga index of two orthocoking coals, subject to extraction with n-pentane, methylene chloride and chloroform, were determined in order to investigate the influence of low-molecular weight substances on coking properties of the coals. With increasing extraction yield, their dilatation and agglomerating capacity were observed to decrease, whereas their softening point was shifted towards higher temperatures. The effect of reduction by potassium in liquid ammonia on dilatometric properties of coals, as well as on their agglomerating capacity, was also studied. This reduction was found to cause a significant increase in coal dilatation, a decrease in softening temperature of the coals, and an insignificant increase in their agglomeration capacity. The extracts obtained from raw and reduced coals are characterized and their role as well as the role of the reduction process in the phenomenon of coal plasticity is discussed.