Synergistic activation of chrysocolla flotation by EDA–DMTD: Interfacial chemical reconstruction and mechanism

Chrysocolla exhibits low flotation recovery because of its strong surface hydrophilicity and the structural constraint of surface Cu active sites, hindering the effective action of activators and collectors. In this study, an EDA–DMTD synergistic activation system was constructed to regulate the surface chemical state of chrysocolla and elucidate its flotation enhancement mechanism. Micro-flotation results showed that, after EDA–DMTD treatment, the recovery of chrysocolla increased to 87.69%, whereas the maximum recovery was only 40.32% when DDTC alone was used. FESEM–EDS and FIB-TEM/HRTEM analyses showed that a continuous interfacial product film with a thickness of approximately 30–33 nm was formed on the chrysocolla surface. XPS detected newly introduced N and S species and identified Cu(I)–S bonding features, confirming the chemical reconstruction of the mineral surface. ICP-OES and ToF-SIMS results showed that EDA promoted the release and migration of Cu, whereas EDA–DMTD enhanced the adsorption of DMTD and DDTC-related species and decreased the signals of hydrophilic species. Correspondingly, the contact angle improved from 20.72° to 91.36°. These results revealed the interfacial mechanism of the synergistic activation of chrysocolla by EDA–DMTD.