To investigate ball mill grinding from the kinetic point of view, the effects of hardness of samples, feed weight and feed size on the grinding rate constant of weight fraction decrease of feed have been studied.
The samples used were silica glass, borosilicate glass, quartz, feldspar, limestone, marble and talc. The pebble mill consisted of a 12.8cm-diameter by 13.2cm-long cylinder and the grinding medium was 40 balls of 3cm diameter having the total weight of 1180g. In the case of wet grinding, 400cc-water was added to the mill. The test were done at the speed of 88.1% of critical one. The experiments were performed on 10 different particle sizes from 4 to 100 mesh for dry grinding and on 8 different ones from 8 to 100 mesh for wet grinding to obtain the grinding rate constants. The following results were obtained.
Dry; K1=0.02HV-0.23·(WS/WB)-1.5·(xf/x0)
Wet; K1=0.06HV-0.23·(WS/WB)-1·(xf/x0)0.7
where K1 is the first order decreasing rate constant of weight fraction of feed, HV the dimensionless Vickers hardness, WS the feed weight, WB the ball weight, xf the feed size and x0 the optimum feed size.
