CONTRIBUTION TO DETERMINATION OF COAL GRINDABILITY
selective grinding (Burstein, 1954 and 1971; Koshina, 1980). It is generally valid that the occurrence of vitrinite in coal increases the HGI value, whereas the micronite and liptinite macerals decrease the grindability (Hsieh, 1976; Hower, 1987). On the basis of research of black coal from Kentucky Hower and Wild (1988) have derived that part of