The Effect of Bubble Size Distribution on Selectivity of Iron Ore Flotation

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Department of Materials Science and Engineering


The effect of the size distribution of air bubbles generated in a flotation pulp on selectivity in mineral flotation was investigated. A theoretical analysis of the effect in terms of the rate of particle collection by bubbles is presented. This analysis demonstrated that the selectivity of flotation depends on both the average bubble size and the width of the bubble size distribution. The selectivity has a maximum value for an intermediate range of bubble diameters. Experiments with flotation of hematite ore were used to confirm theoretical findings. Size distributions of air bubbles generated in the flotation pulp were varied by using different flotation machines and by changing the air flow rate and rotational speed of the impellers. The average diameter of bubbles ranged from 55 μm to 725 μm, and the standard deviation of bubble size varied from 30% to 60% of the corresponding average diameter. Experimental results agreed qualitatively with the theoretical predictions.

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© 1988

Publication Title

International Journal of Mineral Processing