Why Cell Potential is Important for Metal Electrowinning?

Why Cell Potential is Important for Metal Electrowinning?

Electrowinning is an important process in the extraction of metals such as nickel, copper, and zinc. Laterite and sulfide ores are the main source of nickel, a significant proportion of this metal is produced through the electrowinning process.  

Electrowinning is an electrolytic process in which metallic ions are electrodeposited from solutions on the cathode to produce high purity metals. Approximately 80% of the power requirement for a zinc refinery is consumed by the electrowinning process. Moreover, the quality of the final products is determined at this stage. In this process, metal reduction occurs on the cathode and the oxygen evolution reaction (OER) is the main anodic reaction. The electrical energy consumption during the electrowinning process depends on the current density that passes through the cell, which determines the production rate and the required potential difference between anode and cathode. At a constant applied current, the lower cell potential means the lower energy consumption for a given production rate.


Therefore, minimizing the cell potential is essential in the electrowinning process. Although the equilibrium potential for the OER is 1.23V, the reaction does not happen until a significant overpotential is applied. The oxygen evolution overpotential causes approximately 25% of the electrowinning cell potential and the zinc electrowinning power consumption. The oxygen overpotential on the anode electrodes depends on the electrocatalytic properties of the anode materials. Thus, the type of material used for the anode and its electrocatalytic properties determine the OER overpotential, cell potential,  consequently, the energy consumption during the electrowinning process.