Copper selective separation and nanoporous copper oxide preparation from waste copper-clad aluminum scraps

Abstract

Waste copper-clad aluminum (CCA) scraps are secondary resources that are rich in Cu and Al, with biosafety disposal that bears considerable strategic significance in promoting CCA. A process comprising NH3 leaching, NH3 distillation, and roasting was proposed to separate Cu from waste CCA scraps and prepare nanoporous CuO. First, NH3 leaching was performed to separate Cu from scraps. The effects of initial Cu2+ concentration, NH3 concentration, and air flow rate on Cu leaching speed were assessed. Over 99% Cu could be selectively leached, whereas nearly no Al reacted in optimum conditions. Leaching mechanism was analyzed by combining the changes in the potential and pH of the entire NH3 leaching process. Subsequently, NH3 distillation of the leach liquor was carried out to prepare a precursor, which was confirmed to be CuCO3·Cu(OH)2 by X-ray powder diffraction (XRD) analysis. Finally, CuCO3·Cu(OH)2 was roasted, and the effect of roasting temperature on roasted product composition and properties was investigated by thermogravimetry–differential scanning calorimetry, XRD, scanning electron microscopy, and N2 adsorption–desorption. Results indicated that nanoporous CuO (purity, >99%; Brunauer–Emmett–Teller surface area, 44.38 m2/g; pore volume, 0.2690 cm3/g) was successfully prepared. In the entire process, 96.70% NH3 and 98% Cu were recovered via analytical calculation.