Recycling

Biography

Biography: Isabel F.F. Neto

Abstract

The large percentage of Cu present in printed circuit boards (PCBs) residues, usually about ten times more than the Cu amount present in rich-content minerals, makes these residues an attractive secondary source of Cu. The main aim of this work was to develop a simple and nearly-closed two-step process to recover Cu and Al from PCBs residues with high purity.Firstly, a multi-element leaching solution, containing 78 and 85% of the total amount of Cu and Al present in the residue, respectively, together with other metals, was obtained using acidic conditions (HNO3 2M for 210´at 50ºC). The leached solution was constituted by: 66% of Cu and 28% of Al and smaller amounts of Fe, Sn, Zn, Ni and Ag. In a second step, a bispicolylamine resin (Dowex M4195TM) was used to recover Cu with high selectivity. A flow rate of 0.17 mL/min/g of resin was applied to allow maximizing Cu recovery (99.5% of Cu retained). Almost no Al, Fe, Sn and Zn were retained. H2SO4 4 mol/L was used as eluent and 96% of Cu was eluated. The use of DOWEXTM M4195 allowed concentrating the Cu in the final solution (from 18mM of Cu to 31 mM of Cu) and enabled purifying Cu into a final Cu solution with high grade of purity (99.0%). Additionally, the amount of Al (85%), leached from the residue and present in the raffinate, was totally recovered as a solid of Al(OH)3 with 96% of purity.