Recovery of high purity copper cathode from printed circuit boards using ammoniacal sulfate or chloride solutions

The behavior of impurity elements during a copper recovery process from waste printed circuit board (PCB) using ammonia-ammonium sulfate and chloride systems are examined and the performance of these two systems are compared. Leaching of PCB was carried out by solutions containing copper(H) ammine complexes as the oxidizing agent. The copper was selectively dissolved but the leach solution also contained zinc (similar to 1 g/L), lead and manganese (similar to 0.1 g/L), in addition to 40-50 g/L copper. The solution was then purified by solvent extraction using LIX 26 (alkyl substituted 8-hydroxy-quinoline) which typically extracted > 95% of the impurity elements with a few exceptions. The selectivity in the leaching and purification steps was higher in the sulfate system than that in the chloride system. Finally, copper was recovered from the solution by electro-deposition with a low power consumption of 1300 and 500 kWh/tonne in the sulfate and chloride systems, respectively. The results of glow discharge mass spectrometry of the electro-deposited copper revealed that the electro-deposited copper contained 24 and 1.1 ppm of impurities in the sulfate and chloride systems, respectively, with lead as the main impurity element in both systems. Because the purity of the copper deposit from the chloride system was high, this copper scrap recycling process has the potential to recover high purity copper from wastes with a low power consumption. (c) 2007 Elsevier B.V. All fights reserved.