The combination of calcium hypochlorite and fulvic acid as an efficient arsenopyrite depressant in Cu-As separation

In this work, fulvic acid (FA) was tested as a novel arsenopyrite depressant in the flotation separation of chalcopyrite from arsenopyrite with or without calcium hypochlorite (Ca(ClO)2). The flotation behaviors were investigated by single and artificial mixed mineral flotation tests. The depression mechanism of FA and Ca(ClO)2 on mineral surface was uncovered by electrochemical measurement, Zeta potential, contact angle, adsorption capacity, Raman, Fourier Transform Infrared spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS). Flotation tests illustrated that FA had strong depression action on arsenopyrite but hardly influenced the flotation of chalcopyrite with or without Ca(ClO)2. Electrochemical measurement and Raman spectra results showed that the oxidation degree of arsenopyrite surface was higher than that of chalcopyrite. Zeta potential, FTIR and adsorption capacity results illustrated that FA preferred to adsorb on arsenopyrite surface than chalcopyrite surface, and the introduction of Ca(ClO)2 facilitated the adsorption of FA on arsenopyrite surface. XPS results indicated that Ca(ClO)2 promoted the oxidation of arsenopyrite surface to form more iron oxide products. In addition, FA strongly absorbed on arsenopyrite surface via the complexing between hydroxyl groups and Fe oxidized product to form Fe-OH species, preventing the adsorption of sodium isobutyl xanthate (SIBX) on arsenopyrite and rendering it hydrophilic. While FA weakly adsorbed on chalcopyrite surface, which could be substituted by SIBX and regain hydrophobicity.