Kinetics of Grain Size Reduction in Minerals Undergoing Ball Milling

This work focuses on the grain size reduction induced by ball milling in individual minerals and binary mixtures containing quartz and a softer mineral. All the investigated minerals and mineral mixtures undergo a significant monotonic grain size decrease upon mechanical processing. The rate at which the process occurs in individual minerals decreases with the hardness of the mineral phase. Hardness is shown to play a crucial role also in the case of mineral mixtures. The final grain size attainable by the softer mineral as well as the rate of the grain size reduction process depend, indeed, on the amount of quartz in the mixture. A kinetic model allows rationalizing the observed behaviour based on the intensity of mechanical stresses generated during individual impacts.