Effect of particulate environment on the grinding kinetics of mixtures of minerals in ball mills

Abstract

This paper presents the results of the experiments on the effect of particle size distribution and the volume ratio of components of the binary mixtures of calcite, hematite, and quartz on the grinding kinetics in ball mills. A total of forty-six grinding tests were carried out. These included forty-two dry grinding tests and four wet grinding tests. For each test, only one short-duration batch grinding experiment was carried out. The feed charge was prepared by pre-grinding the particulate material in the test ball mill. The results of these experiments have led to several important findings. Three of these findings are: (i) the size distribution of the ground product of the mixture of two minerals was practically the same as the mass-weighted sum of the size distributions of the ground product of these minerals when they were ground alone for the same duration, (ii) fine particles broke faster in the coarser environment, and (iii) while quartz fines were found to be most effective in increasing the specific breakage rate of coarse particles of quartz and hematite, in the case of calcite, hematite fines were found to be most effective. It shows that besides the hardness and density of the components, there are some other presently unknown properties that determine the fraction of the net energy input to the mill that is absorbed by the mixture.