Copper recovery from printed circuit boards: Percolation leaching

Abstract

The aim of this study was recovering copper from Waste Printed Circuit Boards (WPCBs) using a hydrometallurgical process followed by copper electroextraction from the pregnant solution. Samples of WPCBs from obsolete computer were used. The leaching tests were carried out with two particle sizes: +1.00 mm to 1.40 mm and +0.850 mm to 1.00 mm, by percolation using an ammonia-ammonium sulphate system in the presence of hydrogen peroxide as oxidant. The copper leaching efficiency was 96.2 % for the larger particle sizes and 98.4 % for the smaller ones in both tests using stoichiometric conditions of 5 M NH3, 0.5 M (NH4)2SO4 and 2 M H2O2, a pH of 12. Copper recovered by electrowinning was about 99.1 %, but with co-deposition of zinc and nickel.