A NEW ELECTROLYTE FOR COPPER AND SILVER REFINING

Today, technical electro-refining processes for copper exclusively utilize sulfuric acid, while nitric acid electrolytes are employed for silver refining. This study aims to assess an alternative electrolyte for both copper and silver electro-refining. The methodology included characterizing the electrolyte via the determination of current density potential curves and conducting electrolysis experiments at the laboratory scale using technical anodes for copper and synthetic anodes for silver. Key metrics such as solubility of contaminants, composition of anode slimes, current density effects, electrolyte temperature, and impact of various additives were monitored. Performance indicators, including cell voltage, anodic and cathodic polarization, current efficiency, and specific energy consumption, were calculated and compared with conventional sulfuric acid systems. Results indicate that the new electrolyte facilitates the precipitation of smooth copper cathodes with minimal silver and sulfur content at lower temperatures without additives. Furthermore, it allows for the electrodeposition of compact silver sheets that can be extracted similarly to copper electro-refining. These findings highlight the potential advantages and limitations of this alternative electrolyte in practical applications.