Enhanced recovery of copper from reclaimed copper smelting fly ash via leaching and electrowinning processes

Reclaimed copper smelting fly ash (RCA) is generated during the reclaimed purple miscellaneous scrap copper smelting process, and seriously pollutes the environment since it contains Cu, Zn, Pb, Cd and other heavy metals. In this study, leaching and electrowinning process was used for Cu recover from RCA. The effects of RCA and H2SO4 mass ratio, solid-liquid ratio, leaching temperature and time on the leaching efficiencies of Cu, Zn, Pb and Cd were investigated. The effects of current density and electrolysis time on the recovery efficiency of Cu were studied. The results indicated that the leaching efficiency of Cu was 92.52% in the leaching process when the mass ratio of RCA and H2SO4 was 1:0.5, the leaching temperature was 50 degrees C, the solid-liquid ratio was 40 g/L, and the leaching time was 1 h. All the heavy metal contents in the RCA were decreased via acid leaching, and only the Pb content in the leached RCA was higher than the threshold (GB 5085.3-2007). Moreover, the recovery efficiency of Cu was 94.69%, and the Cu purity in the cathode electrowinning powder was 99.21% in the electrowinning process when the the electrolytic time was 1.5 h and current density was 40 mA/cm2. This study provides a new method for the resource utilization and detoxification of RCA.