Effects of operation parameters on particle mixing performance in a horizontal high shear mixer

Particle mixing is an important unit operation in many industry processes. This work employed the discrete element method (DEM) to characterize the mixing performance of iron ore particles in a horizontal high shear mixer. The simulation results were first compared with the positron emission particle tracking (PEPT) data reported by Forrest et al. to validate the DEM model. Then the effects of key operation factors such as impeller rotation speed, number of impellers and filling ratio on the mixing efficiency were discussed. The Lacey mixing index was employed to evaluate the mixing performance. The results show that the mixing efficiency of particles increased with increasing the number of impellers and their rotation speeds. On the other hand, the filling ratio was negatively related to the particles velocity and the mixing efficiency. This was because the effective space left for free movement of particles decreased as the filling ratio increased, and the mixing of particles was therefore restricted. In addition, the mixing rate of particles in the axial direction of the high shear mixer was much slower than that in the radial direction.