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How does electrowinning use electric current to recover metal from a solution?

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Diagram of a zinc-lead blast furnace system showing ore and coke entering through charge hoppers, with labeled furnace, air preheater, blower, taphole for slag and lead bullion, and a connected lead-splash condenser using rotors to separate and cool lead and zinc, with pathways for molten metals and off-gas. — metallurgy A zinc-lead blast furnace and lead-splash condenser. This technology is utilized mainly for producing zinc while managing both lead and zinc from raw materials, a technique that was highly influential in 20th-century smelting.

Electrowinning is a hydrometallurgical process used to recover metals from a solution through electrolysis. In this process, a "pregnant" leach solution—which contains dissolved metal ions—is placed in an electrolytic cell.1234

The setup involves inserting two types of electrodes into the solution:
* Anodes: Typically insoluble materials that facilitate the flow of current.34
* Cathodes: Usually made of a strippable inert material or a thin sheet of the metal being recovered.34

When an electric current is passed through the solution, the metal ions are attracted to the negatively charged cathode. Upon reaching the cathode, these ions gain electrons (a process called reduction) and deposit onto the electrode in a solid, pure form.32

This method is highly valued for producing high-purity metals, such as copper, zinc, nickel, and cobalt, though it is energy-intensive and generally requires a solution with a high concentration of metal ions to be economically viable.341