Simulations based on discrete element method (DEM) were conducted to investigate the effect of particle properties, such as particle/particle sliding friction, particle/particle restitution coefficient, particle density and particle size, on the particle flow in IsaMill. The results were analysed in terms of velocity distribution, porosity distribution, collision frequency, collision energy and power draw. It is shown that by decreasing particle/particle sliding friction coefficient, the flow of particles becomes more vigorous which is useful to grinding performance. Although restitution coefficient does not significantly affect the particle flow in IsaMill, grinding media with higher restitution coefficient should be more effective for grinding because they often have higher collision frequency and collision energy. Heavier particles tend to have higher collision frequency and collision energy but require higher power input, so there may exist an optimum particle density for maximum process efficiency. Grinding medium size also affects the flow and hence grinding behaviour although its selection may mainly depend on the particle size of products. The results obtained from the DEM model should be useful for the selection of grinding media for IsaMill process. (c) 2007 Elsevier B.V. All rights reserved.