DEM Simulation of Dispersion of Cohesive Particles by Spontaneous Inter-particle Percolation in a 3D Random Packed Bed

Spontaneous inter-particle percolation is a common phenomenon in nature and industries. Dispersion of cohesionless particles has been investigated by means of various physical and numerical experiments. However, many granular materials are in cohesive or wet state in metallurgical and mineral processes, and the previous works have a lack of understanding the effect of cohesive force on particle dispersion behaviour. Thus, the present work systematically studies the dispersion of cohesive particles by spontaneous inter-particle percolation in a packed bed using discrete element method (DEM). The results indicate that the vertical velocity of percolating particles increases with increasing the cohesive force from 0 to 2 mg (the gravity force of percolating particle, given by ρ gπd 3/6). While for a higher cohesive force, e.g. f c = 8 mg, insufficient percolation occurs and percolating particles stick in the packed bed. Percolating particles in the packed bed shows a diffusivity for the cases of smaller cohesive force, and the diffusion property can be described by Einstein-Smoluchowski equation. The transverse dispersion of f c = 2 mg is smaller than that of f c = 0, while the longitudinal dispersion becomes larger when the cohesive force changes from 0 to 2 mg. This study provides a fundamental understanding on dispersion behaviour of cohesive particles in a packed bed, and is useful for processes understanding and optimization in cohesive particles handling and mixing.