Enhanced recovery of high purity Cu powder from reclaimed copper smelting fly ash by NH3•H2O-NH4Cl slurry electrolysis system

Reclaimed copper smelting fly ash (RCA) is a residue produced during the smelting process of waste miscellaneous copper, containing heavy metals such as Cu, Zn, and Cd. In this study, a slurry electrolysis system was used to recover Cu from RCA. The results showed that the recovery efficiency, current efficiency, and purity of Cu on cathode were 97.11 %, 91.22 %, and 98.47 %, respectively, when the concentration of NH3 center dot H2O was 2 mol/L, the concentration of NH4Cl was 1 mol/L, the concentration of CuSO4 center dot 5H(2)O was 20 g/L, the solid-liquid ratio was 50 g/L, the electric current density was 30 mA/cm(2) and the reaction time was 2 h. The content of Zn in the RCA decreased from 144.54 mg/g to 23.7 mg/g and Cd from 0.72 mg/g to 0.005 mg/g after slurry electrolysis, and other heavy metals in the RCA also decreased. The potential difference that occurs between the two poles under the NH3 center dot H2O slurry electrolysis system promotes the leaching of Cu from the RCA, while the leached Cu2+ combines with NH4+ to form the Cu-NH3 complex (Cu(NH3)(4)(2+), Cu(NH3)(2+)), thus increasing the current efficiency and promoting the cathodic copper deposition. The high-purity Cu obtained at the cathode belongs to the face-centered cubic structure (111), (200) and (220) of the Cu crystalline surface. This study provides a new method for the resourceful recovery of copper from RCA.