Kinetics of electrolytic deposition of copper from cyanide solutions with a low ligand excess

Regularities of the electrolytic copper deposition from cyanide solutions w ith a constant ratio between total concentrations of ions of ligand and cop per and different concentrations of ions of copper are compared. As the cop per ion concentration increases, effects of redistribution of the surface c oncentrations of various complex forms of copper in the direction of specie s with a greater number of ligand ions, which are caused by an increase in the concentration of free ligand during the electrolysis, become stronger. This enhances the role played by the nature of discharging ions in the form ation of regularities of cathodic polarization, in particular, in the emerg ence of a quasi-limiting current. The regularities may be explained by cons idering the complex ion Cu(CN)(2)(-) as the electroactive species and allow ing for the low effective value of the transfer coefficient, which is close to 0.1. The latter is explained by effects of adsorption of complex ions a nd the ligand at the copper surface.