Recycling of silver-plated brass for production of high purity copper and ultrafine silver powder for electric contacts
Article (Published version)
MetadataShow full item record
The paper presents an improved process for recycling of silver-plate brass housing. Silver and copper are recovered with a purity of 99.99 % and 99.90 %, respectively, with the aim of obtaining materials of higher value using additional procedures based on the same process and equipment. The novel approach with subsequent electrorefining yields copper of 99.99 % purity with BS EN 1978:1998 (Cu-CATH-1) quality and is referred to as LME grade A. Additional processing of silver results in superfine, micro-sized Ag powder with partie size from 0.14 to 1.13 mu m and purity of 99.999 %. Copper electrorefining tests were performed using 1.50 dm(3) of synthetic electrolyte in a 2 dm(3) electrolytic cell. Effects of current density and electrolyte composition were investigated. Optimal current density for the first and second refining was 120 A/m(2) and 200 A/m(2), respectively. Additional refining of silver was performed by chemical reduction from an aqueous solution. Optimal results were obta...ined with ascorbic acid as a reduction agent in concentration of 0.1 mol/dm(3) and polyvinylpyrrolidon as a protective agent in concentration of 2 % by mass. The investigation results could be adopted into production.
Keywords:recycling / copper / electrorefining / silver / micro-sized powder
Source:Bulgarian Chemical Communications, 2014, 46, 4, 814-824
- Bulgarian Acad Science, Sofia