Hydrometallurgical recovery of copper from the leach liquor of waste PCBs.

The present work is focused on the recovery of pure copper metal from leach liquor of discarded printed circuit boards (PCBs) using solvent extraction and electrowinning techniques. Leach liquor containing copper was produced from PCBs of scrap computers using pretreatment followed by the leaching technique. The obtained leach liquor contained 19.35 g/L of copper and 6 M concentration of nitric media. From the obtained leach liquor, systematic solvent extraction and electrowinning studies were carried out for maximum extraction of copper, leaving other metals to be present as impurities. Various process parameters of solvent extraction viz. effect of pH, contact time, phase ratio, and so on were studied and optimized. McCabe–Thiele diagram was plotted, which shows that complete recovery of copper can be achieved in three stages using 40% LIX 84IC and O/A ratio 1/1 at equilibrium pH 2.2 in a mixing time of 20 min. The loaded copper was stripped using 10% H₂SO₄. The obtained strip solution containing 19.35 g/L Cu was electrowinned at the optimized condition, i.e., 8 hours' time and 205 A/m² cathode density with 99.99% current efficiency. 99.8% pure copper metal was obtained. The developed process is environmentally sustainable and has potential to be commercialized after scale-up studies. [ABSTRACT FROM AUTHOR]