Electrochemical dissolution and recovery of tin from printed circuit board in methane–sulfonic acid solution

Abstract

Current industrial Sn stripping processes from raw printed circuit board (PCB) are carried out typically in nitrate system and inevitably produce low-concentration NOX gas pollutant and high-concentration nitrate wastewater. This study proposes a novel and high-efficient Sn electrochemical stripping and recovery method from PCBs in methane–sulfonic acid (MSA) solution. A PCB covered with Sn was used as the anode, and Sn was removed by one-step method and deposited on the cathode in the electrolysis process. This work also investigated the influences of various electrolysis conditions on the change of current efficiency, electric power consumption, and PCB surface morphology. The optimal conditions were 40 °C, 60 g/L Sn2+, 100 g/L MSA, 60 mm inter-electrode spacing, and 200 A/m2 current density for Sn dissolution and extraction. About 85% of Sn was removed from the anodic PCB and subsequently electrodeposited at the cathode under the most suitable conditions. The electric power consumption was 63 kWh/t-Sn, and the electrolyte had a long lifetime. Moreover, the copper layer was not corroded, and no Sn remained on the surface of the anodic PCB after immersion in the picking solution. This novel technique provides an efficient alternative for Sn removal and recovery from PCB and will promote resource recycling and environment protection in raw PCB manufacturing industry.