Numerical investigation of particle size effects on flow characteristics and dilution at the draw point in sublevel caving using a physics-based model

This study investigates the influence of ore particle size on gravity-driven flow behaviour and dilution at the drawpoint in sublevel caving operations using a particle-based modelling framework implemented in the Blender rigid body physics engine. Two representative case studies with non-uniform particle-size distributions are analysed: the Ernest Henry Mine, supported by ring marker trial data, and the DeGagné dilution curve derived from discrete element simulations calibrated against Ridgeway mine data. For both case studies, a systematic calibration procedure is conducted to identify suitable modelling configurations and evaluate the sensitivity of key physics-engine parameters. Half-geometry simulations are adopted to overcome hardware limitations. The results show that particle linear damping is the dominant parameter controlling flow behaviour, while particle friction and geometry also significantly influence flow responses. Simulations using purely spherical particles underestimate inter-particle contact effects and produce less realistic behaviour. The most representative results are obtained using lower damping for ore relative to waste particles and non-spherical dodecahedral particles. Following calibration, increasing ore particle size by 10% and 20% leads to higher dilution and lower ore recovery, particularly at intermediate extraction levels, due to reduced ore mobility and earlier waste breakthrough.