Separation and recovery of copper from waste materials of silver-containing copper-based electrical contact composites

The conventional sulfur-nitration process for recycling silver-containing copper-based electrical contact composites suffers from copper resource loss and generates ammonia-nitrogen wastewater. To address these issues, this study proposed a short-process, high-yield, and pollution-free direct electrolysis method using the H₂SO₄-CuSO₄ system, where the waste material served as the soluble anode and a titanium plate as the cathode. The results showed that under constant pressure of 0.6 V, Cu²⁺ concentration of 40 g/L, H₂SO₄ concentration of 160 g/L, temperature of 60 ℃, and electrolysis time of 10 h, the copper solubility rate reached more than 99.9%, producing high-purity copper of more than 99.9%. In addition, relevant electrochemical tests were carried out to find out the influence of Ni²⁺ concentration on the kinetics of copper dissolution/deposition. The results showed that Ni²⁺ concentration less than 10 g/L was more conducive to the dissolution of anode copper and could promote the electrocrystallization process of copper. In the presence of Ni²⁺, the reduction process of Cu²⁺ was a quasi-reversible reaction controlled by diffusion. A Ni²⁺ concentration of 10 g/L in the solution was found to be the most conducive to the diffusion of Cu²⁺. The Ni²⁺ concentration did not affect the nucleation model of Cu deposition, which was predominantly a mixed model. Under the condition of 10 g/L Ni²⁺, the cathodic copper was sparse and porous with severe particle stacking when the potential was below 0.5 V, whereas a dense and smooth copper layer was obtained at a potential of 0.6 V.