Experimental and DFT study of modified malachite with 2,5-dimercap-to-1,3,4-thiadiazole and its response to sulfidization-xanthate behavior

Malachite is industrially recovered using sulfidization-xanthate flotation. However, due to the instability of the sulfidization effect, it is necessary to strengthen the sulfidization process. To this end, a 2,5-dimercapto-1,3,4thiadiazole (DMTD) can modify the malachite surface for enhanced sulfidization. Analysis of the sulfidization products indicated that more of highly active Cu2S(Cu(I))species and polysulfides (S-n(2-)) were found, indicating that the DMTD-modified malachite surface facilitated the adsorption of S components and improved the surface reactivity. Analysis of the sulfidized surface revealed that DMTD and Na2S together increased the ionic strength of S, further confirming that the DMTD-modified malachite surface facilitates S adsorption. Density Functional Theory (DFT) simulates implicate that the intensified sulfidization of malachite surface is due to the resultant of Cu-S products with various degrees of binding and enhanced interactions between S and Cu atoms. Analysis of the sulfidization efficiency of malachite surface confirmed that the DMTD-modified surface adsorbed additional -S components. Changes in the surface potential and contact angle of malachite suggested that the DMTDmodified surface was higher hydrophobic owing to strong adsorption of xanthate. Flotation experiments confirmed that DMTD can improve the sulfidization-xanthate floatability.