Experimental studies and modeling of surface bubble behaviour in froth flotation

•The horizontal velocity profile of the froth phase in coal flotation was measured.•Comparisons between experiment and model were made.•Six cumulative air recovery functions in the froth transport model were assessed.•The cumulative air recovery function expressed in a power-law was the most suitable. Froth flotation is a versatile, widely used beneficiation technique employing air bubbles to selectively pick up certain particles in aqueous medium. The performance of the flotation process is significantly affected by froth stability and mobility, posing the need for precise control of the froth phase. The present paper aims to understand the motion of bubbles entering the froth phase from the pulp phase at different locations. The horizontal velocities of air bubbles across the top surface of the froth containing fine coal particles were measured. The results showed that at the region farthest from the froth discharge lip, no horizontal movement of the surface bubbles could be observed, and when approaching the lip there would be an increase in the horizontal velocity. The measured velocity profile was fitted to a froth model that considers the cumulative air recovery as a function of location. Six different types of cumulative air recovery functions were tested. The coefficient of determination (R2) and the Akaike information criterion were applied to select the cumulative air recovery function with best fit to describe the horizontal velocity profile. The selected cumulative air recovery function was in a simple power-law form.