Flotation kinetics of molybdenite in common sulfate salt solutions

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 R_Adj ² (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.