Effect of fluoride roasting on copper species transformation on chrysocolla surfaces and its role in enhanced sulfidation flotation

It is difficult to recover chrysocolla from sulfidation flotation, which is closely related to the mineral surface composition. In this study, the effects of fluoride roasting on the surface composition of chrysocolla were investigated, its impact on sulfidation flotation was explored, and the mechanisms involved in both fluoride roasting and sulfidation flotation were discussed. With CaF₂ as the roasting reagent, Na₂S·9H₂O as the sulfidation reagent, and sodium butyl xanthate (NaBX) as the collector, the results of the flotation experiments showed that fluoride roasting improved the floatability of chrysocolla, and the recovery rate increased from 16.87% to 82.74%. X-ray diffraction analysis revealed that after fluoride roasting, approximately all the Cu on the chrysocolla surface was exposed in the form of CuO, which could provide a basis for subsequent sulfidation flotation. The microscopy and elemental analyses revealed that large quantities of “pagoda-like” grains were observed on the sulfidation surface of the fluoride-roasted chrysocolla, indicating high crystallinity particles of copper sulfide. This suggests that the effect of sulfide formation on the chrysocolla surface was more pronounced. X-ray photoelectron spectroscopy revealed that fluoride roasting increased the relative contents of sulfur and copper on the surface and that both the Cu⁺ and polysulfide fractions on the surface of the minerals increased. This enhances the effect of sulfidation, which is conducive to flotation recovery. Therefore, fluoride roasting improved the effect of copper species transformation and sulfidation on the surface of chrysocolla, promoted the adsorption of collectors, and improved the recovery of chrysocolla from sulfidation flotation.