Leaching of silver from silver-bearing residue by a choline chloride aqueous solution and the sustained deposition of silver on copper

Abstract

A novel leaching process has been reported in this paper to extract silver from silver-bearing residue, which was obtained by low-temperature roasting and sulfuric acid leaching of sphalerite direct leaching residue after sulfur separation. The silver in the silver-bearing residue primarily existed in the form of silver chloride by energy dispersive spectrometer (EDS) analysis. The extraction of silver from silver-bearing residue was investigated by using a choline chloride aqueous solution (ChCl-H2O solution). The results showed that 86.91% of silver in the residue was extracted at a liquid-solid ratio of 12–1, leaching temperature of 65 °C, molar ratio of ChCl to H2O of 1–4 and leaching time of 90 min. In addition, the mechanism of silver deposition on the copper surface in choline chloride leaching solution was determined by ultraviolet-visible (UV–vis) absorbance curves and cyclic voltammetry (CV) analysis. When deposited at 65 °C for 210 min, the deposition of silver on copper in the choline chloride leaching solution could reach 0.407 mg/cm2.