Liquid-assisted irregular coarse particle fluidization in a fluidized bed flotation cell: Bed of low-density versus high-density particles

Abstract

Fluidization can enhance coarse particle separation. Here, a three-dimensional computational fluid dynamics (CFD) modeling in a fluidized bed flotation cell is performed to explore the complex insights of coarse irregular particle fluidization behaviours. To address the irregular property of the particle, the classical drag model is modified by incorporating the particle’s shape factor. Simulated particle volume fraction results and experimental data using a fluidized bed flotation cell showed that the irregular particle drag models had a relative error of 3.9% which was significantly better than that of the spherical particle drag models. Thereafter, the CFD model was applied to investigate the bed of low-density irregular coarse particles, 1600 kg/m3, and high-density irregular coarse particles, 2800 kg/m3, at low and high fluidization liquid velocities. It was shown that around 1.7-fold increased density of particles and liquid fluidization velocity increased the bed expansion height roughly 1.8-fold. The time-averaged pressure, volume fraction, apparent viscosity, and velocity of particles are analyzed to explore the fluidization behaviours, particularly within the free settling regime, plug-flow regime, and dewatering zone in the fluidized bed flotation cell. There was a higher apparent viscosity in the dewatering zone than in the plug-flow mixing zone, while the highest apparent viscosity was found in the free settling zone. The outcomes of these CFD studies are significant for the flotation of coarse particles in fluidized beds.