The breakage rates of three different types of iron ore D2, D4 and Joffre from the Brockman Iron Formation, Western Australia were investigated. Batch milling tests were undertaken to determine breakage rates as well as breakage tests using a computer monitored laser detected twin pendulum breakage device. The results showed that Joffre ore was more friable than D4, which was more friable than D2. A set of t-curves were calculated from the pendulum breakage data and a new model was developed. This model was used to satisfactorily predict fines generation from handling and dropping ore samples over a series of 1.8, 5 and 10 m drops. The model developed different degradation matrices for each ore type at the three drop heights and for a given feed. A parameter was also included to account for fines generation due to handling. (C) 2000 Elsevier Science B.V. All rights reserved.