Combined microflotation of glass beads

It is well established that application of microbubbles in combination with coarser ones ensures a significant increase in the flotation efficiency of very fine (< 20 mu m) and very coarse (> 100 mu m) particles. The objective of this study is to determine the impact of microbubbles on the flotation efficiency of medium-sized particles (50-80 mu m). In tests runs we used glass beads (ballotini) of various size grades in the range:50; 50-63; 63-71; 71-80 mu m as flotation objects. We used CTAB as both a collector and a frother at the dosage of 0.06 mg per 1 g of ballotini. Prior to starting flotation by coarse bubbles, a dosage of microbubbles less than 60 mu m in size in the form of a concentrated (66 vol. %) microbubbles dispersion in CTAB solution of (0.2 g L-1) produced by the MBGen-0.012 generator was fed into a flotation cell. The best flotation performance is observed for the fraction of 63-71 mu m, whereas the flotation rate constants for all fractions are directly proportional to the volume dosage of microbubbles, when it does not exceed 0.2mL g(-1). The size of microbubbles significantly affects the flotation effectiveness and depends on the concentration of the collector/frother used for their production. The main mechanism of flotation performance enhancement through microbubbles application, involves formation of coarse aggregates comprising large number of microbubbles and particles, which provides for a significant increase in the capture efficiency of aggregates by coarse bubbles.