Flotation of fine particles in the presence of combined microbubbles and conventional bubbles

Abstract

It is known that fine and ultrafine particles are difficult to float mainly due to their low collision efficiency with bubbles. In this paper, the effect of microbubble addition, on the recovery of fine quartz particles floated with conventional bubbles is discussed. Microbubbles stabilised by collectors were produced using an external air–in–water micro-dispersion generator and added to the pulp in a flotation cell before the introduction of conventional bubbles. It was found that when microbubbles were used, much less collector (about half) was needed to achieve the same or even slightly higher recovery. At the same time, the quartz flotation rate was also higher when microbubbles were used. The advantage of microbubbles may be attributed to a higher attachment efficiency of the conventional bubbles with the fine particles covered with microbubbles. The interaction between microbubble–collector–quartz and the involved mechanism will be identified.