Surface modification of malachite using DMTD and its effect on xanthate adsorption

Malachite is a representative copper oxide mineral, and its direct flotation using the xanthate method is challenging in industrial settings. Therefore, the selection of activators becomes pivotal for malachite enrichment. One such activator is 2,5-Dimercapto-1,3,4-thiadiazole (DMTD), a chelating agent capable of enhancing mineral surface activity through interaction. This property makes DMTD applicable in industrial production, although its mechanism of action remains unclear. This study delves into the activation mechanism responsible for surface modification of malachite using DMTD. DMTD, owing to its superior activation properties compared to Na2S, proves to be more effective in enhancing copper recovery in practical production scenarios. Consequently, the flotation of malachite treated with DMTD significantly improved under identical flotation conditions. Zeta potential experiments corroborated these findings, revealing that the surface modification of malachite using DMTD promotes greater adsorption of butyl xanthate (BX). The Fourier transform infrared spectroscopy (FTIR) results clearly demonstrated the chemical absorption of DMTD onto the malachite surface. Subsequently, the Xray photoelectron spectroscopy (XPS) analysis unveiled the formation of a hydrophobic and stable copper-sulfide species on the malachite surface. Furthermore, time of flight secondary ion mass spectrometry (ToF-SIMS) analysis indicated that DMTD exhibits strong adsorption onto malachite, leading to the generation of CuS- and CuCN- species. Atomic force microscopy (AFM) analysis showed that DMTD predominantly adsorbed onto the malachite surface in a punctate pattern, displaying a uniform distribution across the entire surface. This finding was further validated by the contact-angle test, which confirmed that DMTD-treated malachite exhibited a more hydrophobic interaction with BX compared to untreated malachite. Consequently, the surface modification of malachite using DMTD was found to have a positive impact on BX adsorption, rendering it more hydrophobic.