Surface modification of hemimorphite by using ammonium carbamate and its response to flotation

Abstract

The effect of ammonium carbamate (CH6N2O2) as a complexing agent on the sulfide flotation of hemimorphite was studied through flotation experiments, zeta potential, XPS, ToF-SIMS, AFM, and SEM-EDS. The flotation test results showed that the addition of ammonium carbamate increased the flotation recovery of hemimorphite by 28.28 %. At pH = 8–11, zeta potential results showed that ammonium carbamate can dissolve mineral surface, thus increasing the adsorption of S2− or HS− on mineral surface, and promoting the adsorption of xanthate. The XPS results showed that the ZnS content on the mineral surface after ammonium carbamate complexation sulfidation was significantly higher than that after direct sulfidation. From the ToF-SIMS results, it can be concluded that ammonium carbamate destroyed the surface structure of hemimorphite. After adding ammonium carbamate, a thicker ZnS film was formed by complexation sulfidation, and then covered the mineral surface. It also showed that the complexing agent ammonium carbamate enhanced the adsorption of xanthate on the mineral surface. The AFM results showed that the existence of ammonium carbamate promoted the adsorption of Na2S on the hemimorphite surface, improving the sulfidation effect on the surface and the flotation recovery. The SEM-EDS results showed that after adding ammonium carbamate, the hemimorphite surface better combined with S2− and then formed ZnS on the hemimorphite surface. Therefore, the surface modification of hemimorphite by ammonium carbamate improves the surface hydrophobicity of hemimorphite and improves the flotation performance of hemimorphite, which provides a new strategy and method for sulfide flotation of hemimorphite.