Research on the Mechanism of Comminution in Tumbling Mills

Abstract

This paper discusses the concept that an average comminution event occurring in a ball or rod mill may be a combination of impact, attrition, and chipping of corners and edges. Experimental evidence given shows that the distribution modulus resulting from the impact crushing of single specimens is about ∼1.0, whereas grinding the same materials in a rod mill or ball mill produces material with a distribution modulus that may be considerably <1.0, probably because of attrition and chipping Grinding a mineral as a mixture with a softer mineral increases its distribution modulus, possibly by preventing the mineral from abrading itself. These experiments show that energy consumption in ball mills by minerals in binary mixtures is determined by the volume fraction of each material in the mill; whereas in rod milling, energy is consumed preferentially by the mineral with the lower grindability.