Degradation of steelmaking materials during handling causes a significant economic impact, given the higher prices achieved by lump ore in comparison to finer products. It is relevant to model the amenability of ores to degradation, since it may be used to simulate the response of ores to different sequences of handling and transportation events from mine to port. The paper presents a mechanistic model to describe degradation caused by transfers and drops of particulate materials. The model is based on damage mechanics and the distribution of fracture energies of the original particles, using data collected in impact load cell and tumbling tests. This model, which is capable of predicting the proportion of particles broken and the entire size distribution resulting from any sequence of drops, has been validated at a preliminary level using data from drop tests of a Brazilian iron ore. (c) 2010 Elsevier Inc. All rights reserved.