Effect of flotation frothers on bubble size and foam stability

The experiments described herein indicate that the frothers control the size of bubbles in flotation systems by controlling bubble coalescence. The ability of frothers to prevent bubble coalescence is well characterized by the Critical Coalescence Concentration (CCC). At frother concentrations C lower than CCC, the bubble size is determined by coalescence. At frother concentrations that exceed CCC, bubble size is no longer determined by coalescence but depends on the sparger geometry and hydrodynamic conditions. The efficiency of different spargers can thus be compared only when the experiments are carried out at frother concentrations exceeding CCC. Flotation experiments carried out using small-scale flotation devices (e.g. Hallimond tube, etc.) equipped with either a single capillary or a porous frit may be very difficult to compare. They may give different flotation kinetics because of bubble coalescence in the latter case at C < CCC hence resulting in much larger bubble sizes. The tests revealed that foam stability measured under dynamic conditions is determined by bubble coalescence.Applied Science, Faculty ofMining Engineering, Keevil Institute ofGraduat