Abstract
Cathode potentials of copper during the electrolysis of cyanide copper solutions were measured under the unstirred conditions. Concentrations of the solutions of pH 10 and temperature 30°C, were from 3 to 80g/l CuCN.
The factors affecting cathodic polarization have been discussed. Static potentials of copper were almost constant in a wide range of concentrations of the solution, provided the mole ratio, [CN]/[Cu], of the constituents was kept unchanged. However, the increase in the mole ratio, [CN]/[Cu], in the solution gave rise to the gradual increase of negative potential. When the concentration of copper cyanide in the solution is kept relatively small, polarization increases as the mole ratio, [CN]/[Cu], is decreased. On the other hand, polarization decreases as the mole ratio, [CN]/[Cu], is decreased when the concentration of the solution becomes large. These facts can be explained from the relation between the limit current density of the copper deposition and the concentration of the solution, and from the change of [CN]/[Cu] in the solution adjacent to the cathode due to the liberation of CN- ions during electrolysis.
