Grinding mechanism of centrifugal mills - A simulation study based on the discrete element method

This paper presents a model developed to simulate the family of ball mills, i.e. the tumbling mills, centrifugal mills, vibration mills and planetary mills, and its application especially to centrifugal mills in brief comparison with vibration mills. The model is based on the discrete element method (DEM) and is capable of describing the motion of balls and estimating the energy dissipation, classified by ball-to-ball impact (compression force), ball-to-ball friction (shear force), ball-to-wall impact and ball-to-wall friction. The model uses simple experimental data obtained by compression-crushing tests on particle beds and the restitution coefficient observed by ball-to-ball and/or ball-to-steel plate impact tests. The results obtained by the simulation indicate that the grinding action of centrifugal mills is largely dissimilar from that of vibration mills and that centrifugal mills provide a much higher energy dissipation rate per unit volume of the charge compared to vibration mills at an equal centrifugal coefficient. The results of the simulation imply optimum design and operating conditions of these mills.