copper and nickel recovery from electroplating sludge by the process of acid-leaching and electro-depositing

in this work, we developed a method which combined the processes of acid-leaching, ammonium jarosite precipitating and electro-depositing to recover copper and nickel from electroplating sludge. residual sludge from an electroplating plant located in qingdao was used for acid-leaching, and more than 95% of copper, nickel, zinc, chromium and iron were extracted from the sludge. after acid-leaching, the extracted solution was put into an electrolytic cell for copper recovery by electro-depositing process, and about 95% of copper was recovered under the optimized operation parameters such as cell voltage, ph and electrode material. after copper recovery, the extracted solution was treated with ammonium jarosite precipitating process. about 99% of chromium and iron could be deposited as chromium ferrite in this process. finally, the left solution was treated with electro-depositing process again for nickel recovery, and about 57% of nickel could be recovered in this process under the condition of ph 5.5 and voltage 5.5v.