In production of super-clean coal by any physical coal-cleaning process, the feedcoal must be micronized to liberate finely disseminated mineral matter. One of the most efficient devices for micronizing coal is a stirred ball mill. Using the laboratory mill with a relatively high media loading (80 % filling), small grinding media (less than 1 mm diameter), and three coals, effects of some parameters such as media size, stirring speed, and pulp density on the grinding of coals have been studied. The product with a mediansize of 2μm was obtained at a suitable operating conditions with a mean residence time of 6 min. The wear loss of the grinding media and vessel depended strongly on the amount of the hard minerals disseminated in coal, such as quartz, pyrite and iron oxide.
