An analysis of the selection function for mills using balls as brinding media - In the case of vibration mill

Based upon a simplified grinding mechanism, an analysis of the selection function is made for vibration mills. The mechanism considered is that a particle nipped by two colliding balls is to be ground only if the ball impact generates or activates at least one crack within the particle and the crack is big enough for fragmentation. The derived selection function increases with increasing size up to a certain value and then decreases with increasing particle size. This trend has been observed elsewhere by experiment. Also, the present paper examines the effects of the ball on the selection function.