Fundamental investigation of mixing properties evaluation for Intensive mixer using DEM simulation

Mixing is an important process in various powder handling and operations. Objective of this study was DEM (discrete element method) simulation to grasp mixing properties, especially for mixing rate and final mixing degree, in intensive mixer which is drum typed stirring mill with eccentric agitator and baffle plate. To validate the simulation results, mixing experiments using hematite particles were also conducted. Both in simulation and experiment, various sample size was adopted for mixing evaluation because mixing degree depends on sample size. As a result in experiment, mixing rate and final mixing degree became lower and higher respectively as larger sample size was adopted. Similar trend was achieved in simulation. Furthermore, effect of agitator rotation speed, particle size and mill angle for mixing properties was investigated in DEM simulation. Simulation results suggested that mixing was achieved by early rapid convective mixing, followed by slow diffusive mixing. High rotation speed of agitator made early convective mixing more rapidly whereas it made following diffusive mixing more slowly. When the particle size became larger, convective mixing became dominant. Simulation results also demonstrated that 30° of machine angle brought most rapid mixing rate and total mixing rate became higher in binary components system.