Electrowinning

Electrowinning is the electrodeposition of metals from a solution created by dissolving, or leaching, their ores, and it is described as the oldest industrial electrolytic process, tracing to English chemist Humphry Davy's 1807 electrolysis of molten sodium hydroxide to obtain metallic sodium. The closely related history of electrolytic copper refining includes Maximilian, Duke of Leuchtenberg, demonstrating copper electrorefining experimentally in 1847, English metallurgist James Elkington patenting a commercial process in 1865 and opening the first successful plant at Pembrey, Wales, in 1870, and the Balbach and Sons Refining and Smelting Company of Newark, New Jersey, opening the first commercial plant of this kind in the United States in 1883. Electrowinning differs from electrorefining in its electron balance: electrorefining nets to zero electrons overall, while electrowinning consumes a net positive charge of electrons in the reaction. Today it is used especially to recover metals such as copper and nickel, whose relatively noble character lets them be deposited at mild electrical potentials.