The effect of bubble size on the rate of flotation of fine particles

Flotation experiments have been carried out in a cell in which bubbles of known size could be generated independently of the turbulence levels, which could be controlled by varying the impeller speed. The mean bubble size ranged from 75 μm to 655 μm.Results are reported for the flotation rates of fine particles, less than 50 μm diameter. The materials floated were polystyrene latex particles, quartz and zircon. These were chosen to give a wide range of specific gravity.It was found that the flotation rate was very strongly affected by the bubble size, there being an increase of up to one hundred-fold when the bubble size was reduced from 655 μm to 75 μm. Effects of particle density and impeller speed are also reported.