Copper (Cu) has been recovered from speiss generated from top submerged lance furnace process, but it was reported that the leaching efficiency of Cu in sulfuric acid solution decreased with increasing antimony (Sb) content in the speiss. Scanning electron microscopy (SEM)–energy-dispersive X-ray spectroscopy (EDS) results indicate that Sb exists as CuSb alloy, which would retard the leaching of Cu. Therefore, hydrochloric acid leaching with aeration was performed to investigate the leaching behaviors of copper and antimony. The leaching efficiency of Cu increased with increasing agitation speed, temperature, HCl concentration, and the introduction ratio of O2, but also with decreasing pulp density. The leaching efficiency of Cu increased to more than 99% within 60 min in 1 mol/L HCl solution at 600 rpm and 90 °C with 10 g/L pulp density and 1000 cc/min O2. The leaching efficiency of Sb increased and then decreased in all 1 mol/L HCl leaching tests, and precipitate was observed in the leach solution, which was determined to be SbOCl or Sb2O3 by XRD analyses. However, in 2 mol/L–5 mol/L HCl solutions, the leaching efficiency of Sb increased to more than 95% (about 900 mg/L) and remained, so more than 2 mol/L HCl could stabilize Sb ion in the HCl solution.

No abstract

Cu-Pb and Cu-Sb alloys were prepared at various ratios, from 10:90 to 90:10, and leaching tests with sulfuric acid were conducted to investigate the effect of Pb and Sb on the leaching of Cu from speiss, which is obtained from the top submerged lance furnace process. The Cu leaching efficiency increased as the amount of Cu increased in both alloys, but the leaching efficiencies were lower in the Cu-Sb alloy than in the Cu-Pb alloy. For example, in alloys with 70% Pb and Sb ratio, the leaching efficiency of Cu from the Cu-Pb alloy increased to 95%. The leaching efficiency of the Cu-Sb alloy was 67% in 2 mol/L sulfuric acid solution with 1% pulp density and 1000 cc/min O2 at 90 °C, 400 rpm, and 6 hours. When the leaching residues were examined with SEM (scanning electron microscopy)-EDS (Energy-dispersive X-ray spectroscopy), it was found that in all Cu-Pb alloys, Cu and Pb exist as independent metal phases, while, in Cu-Sb alloys, Cu formed intermetallic compounds with Sb such as Cu2Sb, because the Cu-Sb alloy has a lower melting point than the Cu-Pb alloy. These results suggest that Sb may retard the leaching rate of Cu from the alloy. When the leaching residue of speiss obtained from a top submerged lance furnace, intermetallic alloys of Cu-Sb were also observed, having a net structure. The net structure contains Cu metal in the center of the speiss particle, while the intermetallic alloys of Cu-Sb were present in the outer layer of the particle, in good agreement with the results using the alloys in this study. This suggests the intermetallic alloys of Cu-Sb can prevent copper from leaching.