New insights into the significant drop of molybdenite flotation Recovery: The Overlooked oxidation of MoS2 basal facet

Abstract

The oxidation of molybdenite in water-oxygen system adversely affects the flotation recovery. However, previous studies primarily focused on the oxidation of MoS₂ edge surfaces, neglecting the oxidation of basal facets, which constitute a larger proportion of the overall surface area. In this work, we systematically investigated the oxidation behavior of the molybdenite base surface and explored the influence of base surface oxidation sites on flotation behavior. The results demonstrated that surface oxidation of molybdenite leaded to a negative surface potential, decreased hydrophobicity and reduced dodecane adsorption. Electrostatic potential (ESP) and density functional theory (DFT) calculations revealed that oxidation sites on the molybdenite surface exhibited a strong negative charge, enhancing the adsorption of water molecules while weakening kerosene adsorption. Molecular dynamics (MD) simulations indicated that the oxidized molybdenite surface formed a hydration layer with thickness of ∼ 6 nm, which impedes dodecane adsorption. Moreover, this study proposed an effective strategy to improve molybdenite flotation recovery, that is reducing the concentration of dissolved oxygen in the pulp to inhibit MoS₂ oxidation. These findings provide new insights into the oxidation behavior of molybdenite, and contribute to a better understanding of its flotation behavior in pulp.