Effect of Impurities in Precious Metal Recovery by Electrodeposition-Redox Replacement Method from Industrial Side-Streams and Process Streams

The recovery of precious metals (Ag and Au) by electrodeposition-redox replacement (EDRR) method was studied in three different solutions: sulfate based Zn-Fe-Ag solution, chloride based Cu-Fe-Au solution and industrial multi-metal chloride solution. The common factor to these solutions is that the base (Zn or Cu) metal is present in g/L scale while the precious metal is present in ppm or lower level. The results showed that the presence of impurity Fe (in g/L scale) decreases the recovery efficiency of precious metals but at the same time, it may lead to selective dissolution of the base metal, resulting in the higher purity of the precious metal deposit. Moreover, a successful deposition of Au on carbon nanotube (CNT) films from industrial multi-metal solution was demonstrated.