Ball Mills Mineral Processing Metallurgy13/02/2017· In pebble and ball mills quite often charge volumes close to 50 % are used In a pebble mill the pebble consumption ranges from 3—15 % and the charge has to be controlled automatically to maintain uniform power consumption The volumetric density of a rod and a ball charge is around ton/m³ 310 lb/ corresponding to 37 % void space Sizing of Mills Factors influencing the mill