Peipei Wang, Meolla Yvon, Siân Parkes, Kevin P. Galvin
ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals, Newcastle Institute for Energy and Resources, University of Newcastle, Callaghan, NSW 2308, Australia
Abstract: The recovery and concentration of the nickel sulphide mineral, pentlandite, present several challenges due to its relatively slow flotation, leading to excessive hydrophilic gangue minerals in the concentrate. The REFLUX™ Flotation Cell (RFC™) offers the potential for a significant hydrodynamic advantage over conventional flotation. Much of this advantage is due to replacement of the pulp and froth phases with a concentrated bubbly zone, which in turn supports more intense counter-current washing by permitting a powerful and effective positive bias flux. Thus, the aim of this study was to investigate the nickel recovery and silica rejection in the RFC™, by applying a wide range of positive bias fluxes. The focus was on a single stage of separation in the RFC™ using a feed flux of 0.63 cm/s at a feed nickel grade of 2.1%. At the lowest bias flux of 0.1 cm/s, a nickel grade of 7.5% was obtained at a single stage recovery of 70.2%. By increasing the bias flux to 0.42 cm/s, the grade increased to 9.7% but the recovery fell to 64.9%. With an extreme bias flux of 1.04 cm/s, the grade reached 12.3%, while the recovery fell to 54.7%. The selectivity, given by the nickel recovery relative to the silica recovery, was estimated to be 121 at the highest bias flux, declining sharply with a reduction in the bias flux. The performance ratio proposed by Parkes et al (2022) was quantified by comparing the RFC™ performance with the batch kinetic results from a mechanical cell. The performance ratio was based on the experiment at the lowest bias flux used in the RFC™, and found to be at least 6, meaning the RFC™ footprint would be reduced by a factor of ~6 for a similar product grade. Based on the higher product grades achieved in the RFC™ using the higher positive bias fluxes, the performance ratio would likely exceed 10-fold given the need for the mechanical cell concentrate to undergo at least one further stage of flotation.
Keywords: flotation, Reflux Flotation Cell, nickel, counter-current washing, bias flux