Electrowinning

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Electrowinnning of copper
Electrowinnning of copper

An electrochemical process in which metal dissolved in an electrolyte is deposited on an electrode. This is usually the final stage in the metal extraction process.

Applications

This process is used to recover metals such as zinc, cobalt, copper, nickel, silver, gold, lead and cadmium from solutions obtained from leaching of the mineral ore, waste process streams, etc.

Industrial scale electrowinning is carried out in electrolytic tank cells containing alternately arranged vertical anodes and cathodes. The cathode is normally a sheet of aluminium, stainless steel, titanium or formely a fine starter-sheet of the plated metal. The anode is typically an inert oxygen evolving material such as lead dioxide, platinised titanium or precious metal oxide. The electrolyte is usually an aqueous solution containing the desired metal sulfate and sulfuric acid. A potential difference is applied between the anode and the cathode to induce the electrochemical reaction.

The principal cathode reaction can be represented as follows:

Mn+ + ne- → M

The principal anode reaction is:

2H2O – 4e- → O2 + 4H+

See also

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