A numerical study of the effect of gas distribution profile across the pulp–froth interface on flotation performance

• Effect of gas profiling across the pulp–froth interface was studied numerically.
• Three different gas profiles were studied.
• Comparison of experimental results to simulations was done.
• Changes in froth residence time with variation of gas profile were observed.
• Air recovery also varied with gas flux distribution across the interface.

A solution to the Laplace equation developed using a semi-analytical method termed the method of false transients was used to study the impact of the distribution of gas across the pulp–froth interface on froth performance. Simulation results indicated that profiling gas across the pulp–froth interface has a huge impact on bubble breakage across the surface of the froth and consequently results in different air recoveries. Further, gas flux distribution across the interface also resulted in changes in both bubble and particle residence time distribution. Comparison of predictions from residence time distribution and air recovery to experimental flotation performance was in partial agreement. The discrepancy between model predictions and experimental results was attributed to the fact that the current model does not take into account important froth-phase sub-processes such as bubble coalescence and froth drainage.

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