A phenomenological model of single particle breakage as a multi-stage process

Abstract

Understanding ore breakage is the key for the development of appropriate breakage characterisation experiments. Hence, there has been significant effort to understand a single breakage event, both from the experimental and the modelling standpoints. One particularly interesting approach is to consider breakage of a particle, for instance in a drop weight tester, as a sequence of primary and secondary breakage components. Secondary breakage is defined as subsequent breakage of progeny that takes place after the primary fracture of the parent particle due to surplus energy that is provided by the comminution or breakage testing device. This influences the spatial distribution of fragments as well as their selection. Due to the complex nature of secondary breakage, most of the researches in the past have either been dedicated to understanding primary fracture as a basic element of every comminution process or to describe the breakage process as a whole. However, the progression of breakage may be modelled properly by incorporating the sequential breakage of fragments into a breakage process model. In the paper, a novel approach is proposed to describe a single breakage event by modelling it as a process through several stages of primary fracture while appreciating the effect of sequential fragmentation. The model has three main components: the primary breakage, the selection, and the classification functions. The data that served as the basis for demonstrating this model were a number of impact experiments in an impact load cell on quartz and apatite particles. The results indicate a good correspondence between experiments and model fit. Additionally, a sensitivity analysis to changes in selection and classification functions was performed, which indicated a strong dependency of a breakage event on its sub-processes. It is envisaged that this approach will allow decoupling the contributions of the ore and of the stressing conditions on the outcome of the breakage event.