Effect of ball size distribution on milling parameters

Abstract

This dissertation focuses on the determination of the selection function parameters , a, , and  together with the exponent factors  and  describing the effect of ball size on milling rate for a South African coal. A series of batch grinding tests were carried out using three loads of single size media, i.e. 30.6 mm, 38.8 mm, and 49.2 mm. Then two ball mixtures were successively considered. The equilibrium ball mixture was used to investigate the effect of ball size distribution on the selection function whereas the original equipment manufacturer recommended ball mixture was used to validate the model. Results show that with the six parameters abovementioned estimated, the charge mixture is fully characterized with about 5 – 10 % deviation. Finally, the estimated parameters can be used with confidence in the simulator model allowing one to find the optimal ball charge distribution for a set of operational constraints.