CFD modelling of bubble–particle collision rates and efficiencies in a flotation cell

Computational fluid dynamic (CFD) modelling of a Denver-type flotation cell has been performed. Bubble–particle collision rates in different parts of the cell have been calculated from the local turbulent velocities, and the size and number concentrations of bubbles and particles obtained from CFD modelling. The probability of collision due to streamline effect of fine particles moving around the bubble has also been estimated. The local attachment rate based on the collision rate and collision probability is then calculated and found to decrease as particle size decreases. This is consistent with the decrease in flotation recovery of fine particles as observed in flotation practice. The magnitudes of the collection rate constants obtained from CFD modelling indicate that transport rates of the bubble–particle aggregates to the froth layer may contribute quite significantly to the overall flotation rate in plant-scale equipment.