Novel synergistic mechanism of oxalic acid -CMC at the solid-liquid interface: For selective depression of talc from chalcopyrite

Flotation separation of chalcopyrite and talc is challenging due to their surface hydrophobicity, requiring a selective depressant for talc to achieve high-quality copper concentrate. This study is the first to use oxalic acid (OA) and carboxymethyl cellulose (CMC) as combined depressants for talc, and investigated the depression mechanism through flotation tests and various analysis techniques. Mixed minerals-flotation results showed that with 60+60 mg/L OA+CMC, talc was strongly depressed (10.16% recovery) with slight chalcopyrite (86.54% recovery) impact. The selective depression effect of OA+CMC was further verified through actual ore flotation experiments. Contact angle and zeta potential test indicated that OA+CMC significantly increased the hydrophobicity difference between talc and chalcopyrite surfaces. Adsorption capacity and atomic force microscope(AFM) results further confirmed that OA promotes CMC adsorption on talc surface, forming a dense CMC layer, whereas CMC adsorption on chalcopyrite was relatively low. Scanning electron microscope energy spectrum spectroscopy (SEM-EDS), fourier transform infrared spectroscopy(FTIR), and molecular dynamics (MD) results indicate that the synergistic depression mechanism of OA and CMC involves the formation of multiple adsorption layers at the solid-liquid interface, leading to an increased presence of hydrophilic groups on the talc surface, which results in its depression.