Interface-coupled PbSO4 dissolution and PbS precipitation and its effect on sulfidization flotation of anglesite
(1. Faculty of Land Resources Engineering, Kunming University of Science and Technology, Kunming 650093, China;
2. Yunnan Chihong Zn & Ge Co., Ltd., Qujing 655000, China;
3. Yunnan Key Laboratory of Green Separation and Enrichment of Strategic Mineral Resources, Kunming 650093, China)
2. Yunnan Chihong Zn & Ge Co., Ltd., Qujing 655000, China;
3. Yunnan Key Laboratory of Green Separation and Enrichment of Strategic Mineral Resources, Kunming 650093, China)
Abstract: Anglesite sulfidization mechanism was systematically investigated using flotation tests, X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FESEM), Raman spectroscopy, and ultraviolet- visible diffuse reflectance spectroscopy (UV-Vis DRS). The activation effect of sodium sulfide on anglesite flotation was demonstrated by the flotation tests; however, sodium sulfide concentration must be properly controlled to avoid excessive sulfide ions causing flotation depression. The results of XPS, Raman, and UV-Vis DRS revealed that PbSO4 was replaced by PbS during anglesite treatment with a sodium sulfide aqueous solution. FESEM imaging shows the dissolution of PbSO4 and the precipitation of PbS nanoparticles during sulfidization. Thus, it can be suggested that the reaction of anglesite with a sodium sulfide aqueous solution proceeds via an interface-coupled dissolution–precipitation mechanism: upon contact with a sodium sulfide aqueous solution, anglesite dissolution releases Pb2+ and SO42– into the fluid boundary layer, which becomes oversaturated with respect to PbS phase; then the PbS nanoparticles nucleate and grow on the surface of anglesite. The PbS nanoparticles grown on anglesite can improve the floatability of anglesite.
Key words: anglesite; PbSO4; PbS; sulfidization mechanism; flotation; dissolution; precipitation