Particle/Media Segregation In Dry Ball Milling

Experimental studies of the axial distribution of particles along dry ball mills are described. The results, for mills ranging in diameter from about 10 cm to 1 meter and operated in both the batch and continuous modes, indicate a consistent pattern of significant migration of particles away from the ends of the mill. In some, but less frequent, cases axial migration of the grinding media is also observed. Analysis of the data suggests that particle migration results from end-effects which extend for a distance of about one mill diameter along its length. End-wall roughness appears to play a significant role in the particle migration phenomenon. Media migration is generally associated with continuous mills operating at relatively high powder flow rates.