Influence of boundary conditions in DEM models of sublevel caving on dilution and recovery

Abstract

Discrete element modelling is common approach for analysis of dynamical processes that include granular materials. Method is commonly applied for the modeling of the gravity flow of the broken rock in caving operations. Herein, comparison of two different approaches in such modelling was presented. Two models, ring wide and symmetrically divided, were used for comparison. Ore dilution and recovery were monitored as main comparison parameters, but also the processing time of such models and spatial shape of extraction zones. Ring wide model show greater ore dilution and lower recovery, while half wide models show the opposite results. Cumulative dilution differs for 10%, while ore recoveries differ in approximately 15% for same extraction levels. Also, dilution entrance points are different, where ring wide model shows earlier dilution entrance at about 15% of extraction, while dilution enters at 25% in half wide models. Processing speed is increased in half wide model due to the reduction in number of elements, but overall processing time is nearly the same due to the frequent hang ups inside the half wide model. Shape and size of the extraction zones are very different. Half wide model shows much higher extraction zone in contrary with ring wide, while depth of extraction zone is greater in ring wide models which corresponds with higher and earlier entry of dilution.