Scale-Up Investigation of a Pilot and Industrial Scale Semi-Autogenous Mill Using a Particle Scale Model

A particle scale model based on a full two-way coupling of the Discrete Element Method (DEM) and Smoothed Particle Hydrodynamics (SPH) methods is applied to semi-autogenous grinding (SAG) mills. The methodology involves performing motion and collisions of resolved coarser particles within an SAG mill through the DEM component. Fine particles in the feed combine with water to form a slurry, which is represented by the SPH component of the model. The rheology of the slurry is controlled by solid loading and fine particle size distribution for each volume of slurry. The model predicts the transport, dispersion, and grinding of the slurry phase particle size distribution by solving additional coupled advection–diffusion equations. The grinding of finer particles within the slurry, through collisions and shear of the coarser particles, incorporates population balance terms for each SPH particle. This allows for the prediction of the transport of both coarser and finer materials within the milling process. The developed particle-scale model is utilized to investigate the performance metrics such as throughput, product size distribution, net power draw, and wear for a pilot scale and a 36 ft industrial scale SAG mill.