Extending breakage characterisation to fine sizes by impact on particle beds

Mathematical models used to describe size reduction processes have been undergoing significant advances in recent years, demanding progressively more detailed information characterising ore response to the mechanical environment. In most crushers and grinding mills, the stressing rate is moderate to high, so it is relevant to understand the response of particles to impact loading. Single particle breakage has been a very useful tool to characterise material response for mathematical modelling and simulation of comminution machines. However, finer sizes, which represent a significant proportion of the material contained in most grinding mills, are not generally characterised by breaking single particles given the tediousness involved in conducting the test. In the present work, a standard breakage test that aims at overcoming this limitation has been proposed. It is based on carefully conducted bed breakage experiments and a fitting routine, which allows predicting breakage of particles down to ∼100 μm in size as a function of stressing energy. The model has been calibrated with selected materials and demonstrated to be capable of providing a reasonably good fit to experimental data, as well as to predict breakage at finer particle sizes.