Waste rock segregation during disposal: Calibration and upscaling of discrete element simulations

Abstract

Large volumes of waste rock are produced during mining operations and are often disposed of in large piles on the surface. Segregation caused by particle sizes and deposition methods usually leads to heterogenous internal structures, increasing the risk for hydrogeotechnical and geochemical instabilities. Disposal optimization could improve the geotechnical stability of piles but are difficult to test at field scale. Discrete element methods are therefore used to investigate waste rock flow behaviour. The main challenge is, however, their calibration and extrapolation to field scale. A new calibration process was proposed and tested in this study based on laboratory repose angle tests and field natural repose angles. Calibrated models were then used to reproduce waste rock segregation, which was compared with laboratory and field measurements. Results indicated that numerical models calibrated using repose angle tests were able to reproduce waste rock segregation, and friction and rolling resistance coefficients were scale dependent. • A new method was proposed to calibrate discrete element models for waste rock disposal simulations. • The calibration process was validated at laboratory scale and then extrapolated to field scale. • Repose angle tests and segregation tests were designed for model calibration and validation at laboratory scale. • Input parameters such as friction and rolling resistance coefficients are scale dependent for segregation simulations.