Developments in incremental rock breakage testing methodologies and modelling

• A standard testing methodology was developed for incremental breakage testing.
• Angular and rounded particles were tested under repeated impacts.
• The effect of particle shape and size during incremental breakage was investigated.
• A size dependent equation was developed to model the breakage probability.

In most standard comminution tests, particles are broken in relatively high energy single impact events. However many of the breakage events inside industrial mills are due to relatively low energy collisions, accumulating internal damage resulting in body or surface breakage of particles. Incremental breakage, as it is known, occurs across a wide range of equipment and milling operations. The authors have investigated the probability of breakage during these repetitive impacts. A standardised procedure has been developed for incremental breakage testing where unbroken particles are selected for re-breakage after each breakage event. Breakage probability is then calculated from the relative mass of broken particles. The test results show that incremental breakage occurs under repetitive impacts and the JKRBT is a suitable device for incremental testing. The Vogel and Peukert method for multiple impacts has been modified to more accurately account for size dependency. The influence of particle shape, on the minimum energy of comminution, or threshold energy, Emin, and the applicability of the proposed approach to model the breakage probabilities are discussed.