Why Dimensionally Stable Anodes are Used in Copper Electrowinning?

Why Dimensionally Stable Anodes are Used in Copper Electrowinning?

Copper electrowinning is the recovery of copper metal onto the cathode from the electrolyte. The electrolyte may be the leach solution or the purified solution from solvent extraction. The copper electrowinning cell-house using the conventional cells has many cells. Each cell is a rectangular box having 1 m wide, from 1.5 to 2 m deep, and from 5 to 7 m long. The copper electrowinning cell contains many cathodes and the same number +1 anodes. Copper is plated onto both sides of the cathode sheets, while water is oxidized to form oxygen gas and hydrogen ions on the anode. The rich electrolyte is fed into the cells and then is passed through the cells. Once the copper deposit on one side cathode has plated to the weight of ~60 kg, the cathodes are unloaded from the cell.

Copper electrowinning using inert lead anodes at the beginning. Leach solution from vat leach was employed for copper electrowinning later, the cathode was the starter sheet and the anode was the Pb-Sb alloy. The introduction of copper solvent extraction as the interface between leaching and electrowinning plants improved the quality of copper deposition. Rolled and cast Pb-Ca-Sn anodes have taken place of Pb-Sn anodes because Pb-Ca-Sn anodes have presented better mechanical properties, corrosion resistance, and long life time.

Dimensionally stable anodes (DSA) used in the alkali industry have been proposed and tested in copper electrowinning cell-house. DSA are commonly fabricated from titanium covered with platinum or ruthenium oxide. DSA are chemically stable and do not introduce impurities into the cell. Copper is electrodeposited on a mother plate of titanium or stainless steel. Stainless steel technology has been growing in popularity compared to titanium because of the significantly lower initial capital expenditure.