Simulations were carried out in Metso's DEM simulator so as to draw tip an understanding of the effects the various ways of defining media shapes within the simulator have on the load behaviour and mill power draw. Wits University made available the load behaviour and mill power draw experimental results for the spherical balls, worn balls and cylpebs so as to validate the DEM simulations. The spherical media were defined by a regular spherical shape model and a multi-faceted polyhedron model. Worn balls were defined by super quadric models. A comparison was made between spherical media shapes, non-spherical single media shapes and a distribution of non-spherical media shapes and sizes in representing a load comprised of worn balls. The effect of increasing angularity of non-spherical media shapes on mill power was investigated. The cylpebs were modelled using a regular cylindrical shape model and the effects of friction on the power drawn were determined. (C) 2013 Elsevier Ltd. All rights reserved.