DFT study of sulfidization mechanism of cerussite (PbCO3) and smithsonite (ZnCO3)
(1. State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures, Guangxi Higher School Key Laboratory of Minerals Engineering, School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China;
2. Key Laboratory of Green Separation and Enrichment of Strategic Metal Mineral Resources, Kunming 650093, China;
3. School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China;
4. Low-carbon Technology and Chemical Reaction Engineering Laboratory, School of Chemical Engineering, Sichuan University, Chengdu 610065, China)
2. Key Laboratory of Green Separation and Enrichment of Strategic Metal Mineral Resources, Kunming 650093, China;
3. School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China;
4. Low-carbon Technology and Chemical Reaction Engineering Laboratory, School of Chemical Engineering, Sichuan University, Chengdu 610065, China)
Abstract: The differences in the sulfidization mechanism of cerussite (PbCO3) and smithsonite (ZnCO3) were comparatively studied by the density functional theory (DFT) method. Pb-S/Zn-S layers over PbCO3/ZnCO3 surfaces are constructed to simulate the sulfidization structure. The results of layer distance and Mulliken charge suggest that Pb-S layer formed over PbCO3 is stable but Zn-S layer formed over ZnCO3 is unstable. Because of the high covalency of Pb-S layer and the high ionicity of Zn-S layer, the sulfidization-xanthate method is effective for cerussite but ineffective for smithsonite flotation. To recover smithsonite, strong ionicity collectors are required, and hence the sulfidization-amine method is applied more to smithsonite flotation. These differences in the sulfide layer structure and flotation behavior of PbCO3 and ZnCO3 surfaces are mainly attributed to the different polarizabilities of the metal ions (Pb2+ and Zn2+) and the ligands (O ligand and S ligand) and the inertness of Zn2+ 3d10 orbital.
Key words: density functional theory; cerussite; smithsonite; sulfidization-xanthate method; sulfidization-amine method