A systematic approach was developed to consider liquid-solid reactions with rough solid particles and shrinking particle model. The model is able to predict the reactivities of both non-porous and porous solid particles; the reaction order with respect to the solid material varies from zero (non-porous slab) to one (porous particle). As a model system, leaching of zinc sulphide (sphalerite) with ferric iron in an acidic environment was considered. The modelling was based on experimental data obtained in a batch reactor system, for which both conventional mixing and ultrasound was applied. Rival models based on plausible reaction mechanisms were derived and discriminated qualitatively and with regression analysis. The best model described the leaching reaction as a stepwise process, where ferricions react with solid zinc sulphide in consecutive surface reaction steps. Shrinking particle model a long with the surface roughness approach was used. The model predicts first order behaviour with respect to zinc sulphide, while the reaction order with respect to ferric iron varies from one to two as there action progresses. This is in accordance with experimental observations. The intrinsic kinetics, liquid-solid mass transfer and the effect of ultrasound were well described by the best kinetic model. (C) 2010 Elsevier Ltd. All rights reserved.