The determination of the efficiency of the milling process

Abstract

The results of slow crushing tests in a stiff testing machine for both small and large step reductions of particle size are given. The energy consumption required to produce a given weight of minus 74 fLm. material was determined when both single-crystal quartz and Witwatersrand reef were crushed. For comp.an~on. the two materials tested were also comminuted in a ball mill under optimum conditions. There are indications that slow crushing under stiff conditions is the most efficient method of breakage that can be devised. The comparison with ball milling results thus yields a value for the efficiency of ball milling of approximately 80 per cent. These results confirm that the best current estimates of milling efficiency, which are based on the free boundary surface energy of the material being milled, are probably too Iow by at least one order of magnitude.