Hydrometallurgical recovery of copper from the leach liquor of waste PCBs

Abstract

The present work is focused on the recovery of pure copper metal from leach liquor of discardedprinted circuit boards (PCBs) using solvent extraction and electrowinning techniques. Leach liquorcontaining copper was produced from PCBs of scrap computers using pretreatment followed bythe leaching technique. The obtained leach liquor contained 19.35 g/L of copper and 6 M con-centration of nitric media. From the obtained leach liquor, systematic solvent extraction andelectrowinning studies were carried out for maximum extraction of copper, leaving other metalsto 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 wasplotted, 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 wasstripped using 10% H2SO4. The obtained strip solution containing 19.35 g/L Cu was electrowinnedat the optimized condition, i.e., 8 hours’ time and 205 A/m2 cathode density with 99.99% currentefficiency. 99.8% pure copper metal was obtained. The developed process is environmentally sustainable and has potential to be commercialized after scale-up studies.