Surface nanobubbles and their roles in flotation of fine particles – A review

The study in the field of surface nanobubbles has received great progresses since surface nanobubbles were imaged with atomic force microscopy in 2000. Meanwhile, the interest in developing new flotation techniques for separating fine particles keeps increasing. Surface nanobubbles are showing a great potential of application in the field of mineral processing. The formation of agglomerations composed of fine minerals and the easier attachment of a mineral particle to a flotation bubble are the mechanism for the improved flotation performance in the presence of surface nanobubbles. In this work, various aspects regarding surface nanobubbles including the methods for generation, measurement and identification of surface nanobubbles, the responses of surface nanobubbles to external stimuli including pH, salts, surfactants, temperature, pressure, ultrasonication et al., where flotation is usually performed are summarized. At last, we reviewed recent progresses for surface nanobubbles in flotation. This review gives perspectives for further research in the future.