IsaMill(TM) is a high-speed stirred mill for a range of milling duties from ultra-fine to relatively coarse grinding in the mineral processing industry. This work investigated particle and slurry flow in a mill using a combined Discrete Element Method and Computational Fluid Dynamics (DEM-CFD) approach. Slurry properties, such as flow density and viscosity, were varied to study their effects on the flow properties in terms of flow velocity, power draw, collision frequency, collision energy and total impact energy. Significant differences were observed when slurry was introduced and other conditions unchanged. With increasing density, fluid and particle flows showed stronger circulation in the axial direction due to the larger drag forces. Increased relative velocity and interaction between particles with disc led to higher collision frequency and collision energy. Increase in flow viscosity limited particles from moving towards the outer wall and the particles were more dispersed due to the larger circulating velocity in the axial direction. The total impact energy of the media and power draw also increase with slurry density and viscosity. The developed model provides a useful framework for further analysis of particle-slurry interactions in IsaMills(TM). (C) 2009 Elsevier Ltd. All rights reserved.