CSIRO Minerals develops and applies computational fluid dynamics (CFD) models for minerals processing and energy industry applications. The aim of the program is to improve equipment and processes in these industries and to assist in the development of new processes. Applications are focussed in pyrometallurgy, hydrometallurgy, minerals beneficiation and power generation. The flow dynamics in these areas is almost exclusively multi-phase in nature, and is very often accompanied by chemical reaction and heat transfer, making the models complex in nature. Furthermore, the flows are often influenced by phenomena acting at very different length-scales, and for this reason, CSIRO Minerals are developing multi-scale methods to increase the accuracy of the flow simulations. Examples that will be described in some detail include simulation of fluidised bed reactors and mixer-settlers as used for solvent extraction.