Energy-size reduction of mixtures of anthracite and coking coal in Hardgrove mill

Abstract

Aiming to maximize the utilization of coal resource, heterogeneous grinding of coal in various coalification degrees is common. Interaction among particles of different coals in mixture breakage results in changes of energy-size reduction characteristics if compared with that of single grinding. In this paper, anthracite and coking coals of low ash are ground together in a Hardgrove mill, and resistance to be broken is compared based on the classical breakage model. Product t10 of component after mixture breakage are determined by the relation between characteristic ratio (ratio of height and full width at half maximum of 002 peak) and yield of anthracite coal in mixture. Results indicate that product t10 of anthracite coal increases as more coking coal is added, and that of coking coal shows the contrary trend. A new method is proposed for the determination of energy split factors of components based on the assumption that the relation t10 and spilt energy of component still can be modelled by the classical breakage model. Besides energy split factors of components, breakage indictors are also determined according to above assumption and energy balance by genetic algorithm. Soft coking coal promote the energy-size reduction of hard anthracite coal in mixture breakage, with the increase of breakage indicator (A and b) and energy efficiency compared with those of single breakage. Energy split factors of anthracite coal is above one, and increases with the product fineness. And coking coal shows the contrary trend.