Copper deposition on stainless steel sheets in copper nitrate solution
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Aalto University
Antti Kekki   

Aalto University, 00076 Aalto, Espoo Finland, 00076 Aalto Espoo, Finland
Publication date: 2014-09-01
Physicochem. Probl. Miner. Process. 2015;51(1):247–256
The aim of this study was to examine the factors that influence copper nitrate based electrorefining of copper and to search the best process parameters for high-purity copper deposition on AISI 316L steel blanks. Considering impurities, the most important goal was to minimize sulfur content in copper cathode. The effect of Cu2+ concentration, current density, temperature and pH were studied. The best parameters for the best copper purity were sorted out. The most important factors for quality copper deposition are sufficiently low Cu2+ concentration and low current density and the right zone and careful control of pH. Active nitrate ion reduction reactions catalyzed by copper ions are suggested to affect detrimentally both the copper deposition’s current efficiency and purity. Furthermore, nitrate ion reactions seem to elevate the electrolyte’s pH so that the deposition appears to be dark brow copper oxide. The 6N purity for copper was not reached with this cell construction and it fell behind about 7 ppm (99.9993 % Cu). Sulfur and silver concentration both were slightly above 1 - 2 ppm. To minimize the impurities, electrolyte circulation and filtration is needed. Also, either a separate silver cementation cell or cementation membrane is needed.