Comprehensive recovery of rare and precious metals from copper-rich solution of copper anode slime

Te, Au, Pt and Pd in the copper-rich solution from copper anode slime by sulfation roasting-sulfuric acid leaching treatment were reduced by Fe2+, and new ecological Te colloid were simultaneously formed to selectively capture the precious metals of Au, Pt and Pd. The dissolution mechanism of precious metals in copper-rich solution were analyzed based on pretreatment of copper anode slime. The φ-pH diagram of As-Fe-H2O system were drawn by thermodynamic calculation to instruct the control of electrode potential of the copper-rich solution. The mechanism of in-situ reduction of rare and precious metals were discussed based on electrode potential of main metal ions in copper-rich solution. Under the optimal conditions of reaction temperature of 85℃, reaction time of 1.5h, stirring speed of 300r/min, and Fe2+ dosage of 2g/L, the precipitate efficiency of Au, Ag, Pt, Pd, Se, Te and As were 100%, 100%, 99.2%, 99.6%, 33.3%, 36.1% and 16.8%, respectively. The grades of Te, Au, Ag, Pt and Pd in the precipitated residue are 18.24%, 124g/t, 10.54%, 1010g/t and 320g/t, respectively. XRD analysis shows that the main phase of the residue is AgCl, and other components did not show obvious diffraction peaks due to amorphous or low content. The microscopic morphology of the residue is mainly fine powder and particles. SEM images of the residue shows that Ag and Cl have obviously consistent enrichment areas, As and Fe have similar enrichment areas to form AgCl and FeAsO4 in the residue. The proposed process environmentally friendly and low cost with simplicity in operation, which had achieved efficient and comprehensive recovery of rare and precious metals in copper-rich solution. © 2021, Chemical Industry Press Co., Ltd. All right reserved.