Flotation kinetics of molybdenite in common sulfate salt solutions

Abstract

This study investigates the kinetics of molybdenite (MoS2) flotation in sulfate media (Na+, K+, Ca2+ and Mg2+) with a concentration of 10−4–10−2 M. Results indicate that both monovalent and divalent cations inhibit MoS2 flotation. Three flotation models were used to fit the flotation kinetic data. The Gamma model gives the best goodness of fit in terms of RAdj2 (adjusted coefficient of determination) and RMSE (root mean square error), however, fails in predicting MoS2 flotation recovery in MgSO4 solution due to the contradictory to the actual flotation trend. In contrast, the rectangular model fits MoS2 flotation in all the sulfate solutions. The flotation rate constant k values decrease with increasing sulfate concentration, indicating that the increased sulfate concentration reduces MoS2 flotation rate. The lowest k was found in the MgSO4 media, suggesting that MgSO4 is most detrimental to MoS2 flotation recovery. In addition, the R∞ was decreased with increasing sulfate concentration in an order of Mg2+ > Ca2+ > K+ > Na+, with the minimum R∞ being obtained in 10−2 M MgSO4, probably due to the formation and adsorption of hydrophilic Mg(OH)2 onto MoS2 surface.