Grinding kinetics of steady-state feeds in locked-cycle dry ball milling

The size-discrete breakage rate and distribution parameters of the grinding kinetic model are mostly determined in laboratory batch mills using single-size feeds. However, there is evidence in the literature that particle size distribution in the mill affects the breakage parameters. Previous work studying this effect was mostly conducted with feeds whose size distributions were not closely representative of those normally dealt with in industrial mills. This study was undertaken with the main purpose of investigating the effect of particle size distribution on the breakage parameters of quartz and calcite minerals in dry ball milling using steady-state feeds obtained from Bondʹs locked-cycle tests. Different closing screen sizes were used in the locked-cycle work to produce different feed size distributions that would resemble feeds to industrial closed-circuit ball mills. Experimental results have shown that the breakage rate parameter of the top size interval increases as the feed size distribution in the mill becomes finer. There is some evidence implying grinding-environment dependency of the non-normalizable breakage distribution parameters. The cumulative-basis one-parameter linear population balance model gives a simple and reliable representation of the kinetics of closed-circuit dry ball milling.