LAUSR

Abstract Crushing and grinding process in mineral processing industry is high energy consuming but it is essential for generating required sized ore with improved liberation, which enhances the process efficiency of physical cleaning of ore. Due to the presence of various minerals in lump of ore, breakage mechanism plays a major role in liberation of different materials, which is solely depends on the type of force applied for crushing and grinding. In conventional crushing and grinding equipment, high impact and attrition forces are applied on the ore lump, which breaks the grain mixture homogeneously, but mineral cleaning enhances when there is a breakage through grain boundaries and not through the grains. Coal is a carbonaceous ore contains maceral and minerals with different properties. Due to the presence of high mineral content, the mineral beneficiation process is adopted where the liberation of inorganic minerals plays key role. As coal is a soft material, use of impact mills generates coal with homogeneous distribution of minerals. In this paper, Autogenous grinding method explored for coal to study the effect on liberation of coal and it was observed that, autogenous grinding helps in improving the liberation of minerals. Experiments also revealed that, the autogenous grinding produces clean coal fines with low ash percentage(16.5% ash clean coal from 24.4% ash feed coals) directly without washing. It was also observed from petrographic study that liberation of coal improved in comparison with conventional grinding process. This is due to the breakage of the coal particles through the coal and mineral boundary.