Mechanistic Insights into the Reaction of Wulfenite with Aqueous Sodium Sulfide Solution and Its Industrial Implications

The purpose of this study was to investigate the reaction mechanism of wulfenite with an aqueous sodium sulfide solution and thereby provide guidance for the sulfidization flotation and sodium sulfide leaching of wulfenite. For this purpose, dissolution/leaching behavior analysis, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscopy (FESEM) were performed. The dissolution/leaching analysis indicated that sodium sulfide can induce the dissolution of PbMoO₄. The XRD and Raman spectra results demonstrated that PbMoO₄ was replaced by PbS at the wulfenite-sodium sulfide solution interface, and the sulfidized wulfenite particles had a PbMoO₄/PbS core-shell structure. The XPS results also indicated the transformation of PbMoO₄ to PbS. The FESEM images showed the growth of PbS nanoparticles on the surface of wulfenite and the dissolution pits after treatment with sodium sulfide solution. These findings showed that wulfenite sulfidization proceeds through an interface-coupled dissolution-precipitation mechanism. In the presence of sodium sulfide solution, the less stable PbMoO₄ dissolves, and the more stable PbS phase precipitates, both of which are coupled at the wulfenite-sodium sulfide aqueous solution interface.