The use of the discrete element method and fracture mechanics to improve grinding rate prediction

The Discrete Element Method (DEM) is a numerical technique that can simulate the interaction of discrete particles in dynamic environments such as fluidised beds, jigs, flow in bins, screens and mills. This technique has great application potential in comminution modelling at micro-process level. The DEM is being used to determine the grinding rate of ore particles in an Autogenous mill. The frequency of the contact events and the associated energy dissipations derived from the simulation are used to determine the particle failure rate. The probability of particle failure also depends on the inherent fracture properties of a material; hence fracture tests were conducted on an ore sample using a drop-weight impact test machine to obtain a probability fracture model. A second model that uses energy dissipation spectra from the DEM and probability fracture model calculations has been proposed. Though the model tends to over-predict breakage generally, there are indications that the model is responsive to changes in the load behaviour. (C) 2001 Elsevier Science Ltd. All rights reserved.