elektrowinning

Electrowinning, sometimes written elektrowinning in non-English texts, is an electrochemical metallurgical process used to recover metals from dissolved ions by electrodeposition. In hydrometallurgy, electrowinning is commonly employed to produce metal cathodes directly from solutions resulting from leaching or solvent extraction. The most familiar example is copper electrowinning, where copper ions in an acidic copper sulfate solution are reduced to metallic copper on the cathodes, while the anodes (often lead-based alloys) either dissolve to supply Cu2+ or evolve oxygen gas, depending on the cell design.

The electrolyte is typically copper sulfate with sulfuric acid; operating temperatures are moderate; current is supplied by direct current rectifiers; cell design features multiple cells and large-area cathodes, often arranged in modules. In solvent extraction-electrowinning (SX-EW) plants, ore is leached to produce a pregnant solution, copper is extracted as Cu2+ in an organic phase, then stripped to yield a copper sulfate electrolyte that is fed to the electrowinning cells to deposit copper on cathodes.

Cathode reactions involve the reduction of metal ions: Cu2+ + 2 e- → Cu(s). Anode reactions vary with design: with inert anodes, water oxidation to O2 occurs; with sacrificial copper anodes, Cu → Cu2+ + 2 e-. Electrowinning can also be used for other metals such as zinc, nickel, cobalt, or gold from suitable solutions.

The process is a core step in many mining operations and enables production of high-purity metal with relatively straightforward downstream handling, but it requires careful control of electrolyte composition, temperature, impurity management, and energy consumption.