The angle of repose and size segregation of iron ore granules: DEM analysis and experimental investigation

We have developed a DEM model to study the packing characteristics of iron ore granules. Two important indices in characterising the packing of granules, i.e. the angle of repose (for packing stability) and a size segregation index, were obtained from the simulations. The comparisons of the simulated and experimental angle of repose and size segregation indices showed good agreement, demonstrating that the developed model is capable of predicting the behaviour of iron ore granules during pile formation. The simulation results show that the angle of repose of iron ore granules was greatly influenced by granule size, sliding and rolling friction coefficients. A decrease in granule size or an increase in either the sliding or rolling friction coefficients significantly increased the kinetic energy dissipation rate of the discharged granules during the packing process. Therefore, an increase in granule pile stability was observed. The simulation results also demonstrated the presence of significant size segregation of iron ore granules in the pile in the horizontal direction. The average granule size in the outer section of the pile was relatively larger than that in the central section. However, in the vertical direction, due to the interaction of multiple segregation mechanisms, size segregation was not clearly observed.