Mixing characteristics of micron-sized cohesive particles induced by high-intensity vertical vibration

The mixing characteristics of micrometer-sized cohesive particles under the action of high-intensity vertical vibration were investigated by the discrete element method (DEM). To reduce the computational burden of simulation studies of micron-sized particles, coarse-grained treatment of particles is performed. This study encompasses an analysis of the motion states and collision dynamics of the micron-sized cohesive particles. Under vertical vibration, the combined force on the particles by the container dominates the agglomeration and dispersion between particles. Agglomeration and dispersion will gradually reach an equilibrium state, which presents the final mixing index. An increase in either vibration amplitude or frequency improves the mixing rate and effective power but reduces the mixing quality when further increased. An increase in the surface energy between particles increases the interparticle viscosity, which significantly reduces the mixing rate and improves the mixing quality, but also increases the energy required to reach the stabilization stage. An increase in container height has an enhancing effect on the mixing quality and effective power and does not increase the energy absorbed to reach the stabilization phase. From the analysis of collision dynamics, the vibration parameters and container height all affect the mixing state by changing the collision energy between particles, while surface energy changes the inter-particle separation energy. The research will help to reveal the microscopic phenomena of particle motion and to find support for more efficient and less energy-intensive mixing conditions during the mixing of micron-sized cohesive particles under vertical vibration.