Waste rock disposal and segregation: Validation and upscaling of discrete element simulations

ABSTRACT: Large volumes of waste rock are usually produced during mining operations and are often disposed of in large piles on the surface. Particle segregation caused by particle size distribution (from fine particles to meter wide blocks) and deposition methods (e.g. end dumping), usually lead to complex heterogenous internal structures, increasing the risk for instabilities. Disposal optimization could improve the geotechnical stability of piles but are difficult to test at field scale. The Particle Flow Code (PFC; Itasca) was used in this study to investigate the behavior of waste rock during disposal. Repose angle tests and segregation tests were conducted in the laboratory to calibrate and validate numerical simulations. The effect of maximum particle size was investigated. Results show that friction coefficient and rolling resistance coefficient can significantly affect the macro-properties of waste rock and are strongly related to the particle size. Relationships between numerical parameters (e.g. friction coefficient and rolling resistance coefficient) and rockfill particle size were proposed and extrapolated for field applications.