The discrete element method(DEM)was applied to simulate the solids motion in the rotating drums and analyze the structure characteristics of the particle bed under the rolling mode in the rotating drums.The results show that

the simulation value on particle cycle time

the maximum velocity of particles in the active layer

the maximum thickness of the active layer

the ratio of the maximum thickness of the active layer to the maximum depth of bed are consistent with the calculated values of the theoretical model.The particle cycle time decreases with the increasing speed and increases with the filling rate and the diameter of the drum.The maximum velocity of particles in the active layer increases with the speed

the filling rate and the diameter of the drum.The maximum thickness of the active layer increases with the speed

the filling rate and the diameter of the drum

and theδ/hdecreases with the increasing speed and the drum diameter but increases with the filling rate.