The design and scale-up of ball mills are important issues in the mineral processing industry. Incomplete knowledge about the mechanics of charge motion often forces researchers to rely on phenomenological modeling to formulate scale-up procedures. These models predict the behavior of large industrial-scale mills using the data obtained in small laboratory-scale mills. However, the differences in charge motion in plant-scale and lab-scale mills introduce significant inaccuracies in the predictions. In this article, a batch-grinding model using the impact energy distribution of the mill is explained. The distribution of impact energy is obtained from the simulation of the charge motion using the discrete element method. The model is also verified with experimental data, and the strengths and the weaknesses of the model in its current form have been identified. It is anticipated that a model, which uses information about impact-energy distribution will overcome some of the difficulties faced by the phenomenological models. (C) 2002 Elsevier Science B.V. All rights reserved.