Abstract
Selection function and breakage distribution function of a tumbling ball mill were derived theoretically by measuring the impact force of balls on the mill shell and by considering the fracture properties of powder particles under compressive impact force. As a result, conversion ratio of the input energy into the impact energy of balls on the shell was found to be very low and the derived functions disagreed with the measured ones. From these results, grinding process of the tumbling mill was presumed to consist of fracture process of the powder particles under the compressive impact force and frictional crushing process under the shear force.
