Effect of calcium ions on the surface properties of heterogenite and conducive to sulfidization flotation: Insight from oxygen vacancy

It is challenging to obtain a satisfactory sulfidization effect via direct sulfidization of heterogenite, and the introduction of Ca2+ to modify the surface property of heterogenite could improve its sulfidization. Tests using ICP-OES and SEM-EDS showed that Ca2+ modified the surface morphology of heterogenite, facilitating sulfur ion adsorption. FT-IR and Raman spectrometer analysis revealed that the pre-treatment of Ca2+ was beneficial to form more Co-S bonds on the surface of heterogenite. XPS analysis indicated that Ca2+ modified heterogenite surface properties by creating more oxygen vacancies, which was further supported by EPR test results. DFT calculations further show that oxygen vacancies could increase the adsorption capacity of Co sites on the heterogenite surface. Furthermore, micro-flotation tests showed that the surface modification of Ca2+ could significantly improve the sulfidization flotation recovery of heterogenite. This study found calcium ions enhance the sulfidization of heterogenite by inducing surface oxygen vacancies, which provides a new perspective for understanding and enhancing the sulfidization process of heterogenite and contributes to the efficient recovery of cobalt oxide ore.