Hydrodynamics of froth flotation and its effects on fine and ultrafine mineral particle flotation: A literature review

Variables of hydrodynamics are equally important as those of surface chemistry in determining the efficiency of froth flotation processes. In a mechanical flotation cell, macro hydrodynamics is responsible for solids suspension and aggregates transport, and micro-turbulence plays an important role in the sub-processes of flotation, such as gas dispersion into small bubbles and bubble-particle collision. Generating optimal hydrodynamic regimes will benefit these sub-processes. Despite the growing research attention, flotation hydrodynamics remains a poorly understood field, especially with respect to its effects on fine and ultrafine minerals flotation. In this work, we have reviewed factors influencing flotation hydrodynamics and the characterization of flotation hydrodynamics at different scales. In particular, the effects of hydrodynamics on fine and ultrafine particle flotation processes, including bubble-particle interaction, gas dispersion, flotation kinetics, fine bubble generation, mineral particle size enlargement, and mechanical entrainment have been discussed. Recent thoughts expressed in the literature are introduced, together with recent advances of improving fines flotation by hydrodynamics optimization in cell design using the reactor-separator concept. This review may improve the overall understanding of flotation hydrodynamics and provide guidance for solving the problems in fine and ultrafine minerals flotation from the hydrodynamics perspectives. Research gaps are identified and opportunities for future work are suggested.