Tin, silver, and copper sulfate compound extraction from lead-free solder dross by reduction with petroleum coke, electrorefining, cementation, and crystallization process

Abstract

Solder dross, a waste by-product from the electronic component dipping bath, contains significant quantities of valuable metals. This study presents a four-step process for recovering tin, silver, and copper from lead-free Sn-Ag-Cu solder dross. The process involves the initial reduction of the dross using petroleum coke to produce an anode plate, followed by electrorefining to extract tin from the anode plate. Selective leaching of silver and copper from the residual anode slime and cementation techniques are employed to recover silver powder. The rest of the copper solution was used to synthesize copper sulfate crystals. Experimental results demonstrate optimal conditions for the reduction process, resulting in a high tin recovery rate of 92.88%. The electrorefining step yields tin with a purity of 99.94%. Silver and copper are successfully recovered from the anode slime, achieving purities of 99.60% for recovered silver powder and 99.90% for crystallized copper sulfate compounds. This comprehensive study offers insight into the efficient extraction and recovery of tin and other valuable metals from lead-free solder dross.