Maximising Flotation Kinetics

Low pulp density and low grade streams in the coal and minerals industries are generally discarded to waste due to the low or negative financial return and large capital investment required. Yet, such losses to tailings dams are likely in the billions of dollars each year. The challenge facing the coal and mineral processing industry is to enact separation of very fine particles without forgoing the rate of throughput per unit area of vessel. The challenge arises due to particle sizes falling below the optimum diameter required by conventional gravity-separation processes, including flotation. In this study, a novel approach to rapidly process low pulp densities feeds is investigated using a device, referred to as the Reflux Flotation Cell (RFC), which incorporates a system of inclined parallel channels below the main vertical chamber to enhance the segregation rate between bubbles and liquid. This enables the use of very fine bubbles to promote the kinetics of particle recovery, promote high gas rates to increase the bubble interfacial flux passing through the system and rate of particle-bubble collision, and utilise extremely high feed fluxes to reduce the cell residence time to below 30 s. By simultaneously maximising segregation and kinetics of flotation, while reducing the residence time, this study aims to achieve near complete combustible recovery of fine coal particles from low pulp density feeds using fast flotation.