Interaction of applying stable micro-nano bubbles and ultrasonic irradiation in coal flotation

Due to the short life of nanobubbles in the pulp, their use in mineral processing, especially in fine grains, is rare. Hence, the use of sustainable nanobubbles with a long lifetime can lead to new results. In addition to the presence of micro-nano bubbles, the ultrasonic emission factor can also have a positive effect on flotation performance. The simultaneous effect of these two factors has not been considered in previous studies. In this study, the stable micro-nano bubbles produced by the hydrodynamic cavitation mechanism were used in the pulp and simultaneously the ultrasonic waves were irradiated. Under these conditions, a wide range of bubbles ranging from 80 nm to 1 mm was generated which caused the flotation of the fine to coarse size particles. Simultaneous use of these two factors showed that the yield of coarse (−850 + 420 µm), medium (−420 + 105 µm) and fine (−105 µm) particles improved by more than 10%, 10%, and 30%, respectively. Combustibles recovery in variable feed ash along with the ash selectivity index were enhanced. In addition, consumption of the collector was reduced up to 90%, while the concentration required for the frother agent was reduced to approximately a quarter.