Grinding dynamics and discharge efficiency within semi-autogenous （SAG） or autogenous （AG） mills are predominantly determined by the mill liner design. Due to the mill size， it is difficult to quantitatively investigate the dynamic discharge flow performance with physical experiments. This research aims to utilize a coupled discrete element modelling and smoothed particle hydrodynamics method to model the two-phase mineral slurry within grinding mills. Two distinctive mill liner designs， radial and curved discharge end， were selected and the developed numerical framework was employed to quantitatively compare the discharge efficiency of a selected mineral slurry. A rotary viscometer was initially used to calibrate the numerical modelling parameters to ensure the flow dynamics of the slurry to reflect its actual behaviour. Numerical modelling was conducted and the results indicated that the curved discharge end showed 13.4% throughput increase and 93.3% reduction on back-flow in pulp lifters. Modelling results were validated by site measurements.