Sulfidation behavior of copper ferrite induced with sulfur and flotation responses

In this study, sulfidation roasting was used to modify the copper ferrite to improve its flotation performance for the first time. The flotation results showed that the recovery of modified copper ferrite reached 91.63 %. The sulfidation mechanisms of copper ferrite at high temperatures were systematically investigated by X-ray diffraction (XRD) combining with thermodynamic calculations, X-ray photoelectron spectroscopy (XPS) and electron probe microanalysis (EPMA). XRD and thermodynamic analyses revealed that the CuFe₂O₄ was first reduced to compounds of Cu₂O and Fe₂O₃, and was then converted to Cu₂S and Fe₃O₄ with the increase of sulfur dosage at high temperatures. XPS analyses indicated that both the Cu₂S and CuSO₄ were mainly formed on the surface of mineral after the sulfidation treatment. The EPMA analyses confirmed that Cu₂S was generated at the outer layer of samples after the sulfidation, while the inner part of particles was mainly composed of Fe₃O₄. It is concluded that the sulfidation reaction of CuFe₂O₄ occurred from the surface to interior during the thermal process. The sulfidation reaction pathway was devised as the follows: CuO·Fe₂O₃ → CuO_x·Fe₂O₃(0 < x < 1) → Cu₂O + Fe₂O₃ → Cu₂S + Fe₂O₃ → Cu₂S + Fe₃O₄ to better interpret the transformation mechanisms of CuFe₂O₄. These results will provide a good theoretical basis for the recovery of Cu and Fe from the refractory oxide copper resource by the combined methods of sulfidation and flotation.