The introduction of ceramic milling media specifically designed for high energy mills has resulted in significant improvements in both milling efficiency and the overall economics of mineral processing. Three media types were trialed in an Xstrata Technology M4 IsaMill to ascertain mill performance. Mill performance was related to media density, size, and friction. Based on these results, a model that incorporates media properties was developed and validated to predict milling performance and can be used to tailor milling media for specific applications. (C) 2009 Elsevier Ltd. All rights reserved.