Electrorefining zinc dross in ammoniacal ammonium chloride system

A zinc dross was cast into anodes and electrorefined in an ammoniacal ammonium chloride electrolyte (NH3–NH4Cl) to produce high purity zinc. The influence of several factors, such as zinc concentration, current density and temperature, on cathodic current efficiency and power consumption were investigated. The results indicated that increasing Zn concentration increased the current efficiency, but, very high Zn concentrations affected the progress of the electrolysis of zinc dross. The power consumption can be decreased effectively by increasing the temperature of electrolyte. High current density adversely affected the quality of the cathodes and increased the power consumption. The morphology of cathodic zinc can be improved by increasing Zn concentration at an appropriate current density and its purity was very acceptable. All the experimental results obtained showed a technical feasibility of the NH3–NH4Cl system as an electrolyte system for electrorefining of zinc dross.