Regulation of bubble size in flotation: A review

During the flotation process, hydrophobic minerals are transferred to the foam by bubbles. The size of bubbles has a significant influence on the capture probability of the bubbles and particles, hence affecting the flotation efficiency. Effective regulation of the bubble size is a premise for achieving a controllable flotation index. This paper reviews studies of the regulation of bubble size. The bubble generation, evolution, and action mechanism of different factors on the bubble size are elucidated. It is shown that mechanical stirring, variable pressure (dissolved air, jet, and vacuum), porous medium, ultrasound, and electrolysis are usually used to generate bubbles during flotation. The bubbles generated continuously evolve (i.e., deform, break up and coalesce) to form bubbles of a stable size in the flotation cell, and the bubble size depends on the equilibrium of the breakup and coalescence. The frother, collector, slurry properties, mechanical energy input, and air flow rate are the main factors influencing the bubble size, and bubble size has been regulated using a single factor. This review proposes that research on the regulation of the bubble size should focus on the industrial application of micron-sized bubble generation technology and the effect of multi-factor coupling on the bubble size.