Investigating the effect of applied strain rate in a single breakage event

For successful mechanistic modelling of any size reduction equipment, an understanding of the fundamentals of the breakage mechanisms is essential. This understanding will allow the comparison of breakage events and the quantification of the effect of key factors such as applied strain rate, particle size, and particle shape while they are isolated. This paper uses the concept of analysing breakage of a single particle as a multi-stage process to compare different breakage mechanisms and to quantify the effect of factors such as applied strain rate. This approach regards a single breakage event as a process affected by three sub-processes; first (or primary) fracture, capture and spatial distribution of fragments. The first fracture is assumed to be independent of breakage mechanism and to be a characteristic of the ore type. On the other hand, capture and spatial distribution are influenced by the characteristics of breakage environment, the kinetic energy of fragments and their brittleness. The focus of this paper is to examine how each sub-process of a breakage event is influenced by applied strain rate and its impact on the size distribution of progeny. In this work, three rock types of widely different strength and brittle behaviour, i.e. LKAB magnetite ore, Beaudesert silicate and Bundaberg quartz, were tested at various energy levels using the impact and compression breakage mechanisms. To isolate the effect of spatial distribution of fragments, particles were forced to remain in the breakage zone. In this condition, similar progeny size distributions were generated from compression and impact mechanisms at similar energy levels. However, allowing natural distribution of fragments produced coarser progeny from the compression of silicate. (C) 2016 Published by Elsevier Ltd.