Electrowinning

Electrowinning is a metallurgical process that uses electrolytic deposition to recover metals from aqueous solutions. In an electrolytic cell, metal ions dissolved in an electrolyte migrate to the cathode under applied current, where they are reduced and deposited as a metal. The anode can be an inert material or a dissolving electrode that replenishes metal ions in solution. The method is widely used in hydrometallurgy to produce relatively pure metal products from leachates or regeneration solutions.

Typical flow involves leaching ore to produce a metal-rich solution, followed by purification and adjustment of the electrolyte. An electrical current is passed through the cell, causing metal to plate onto cathodes. The process can be continuous or batch-based, and cathodes are periodically stripped, refined, and reintroduced. Common metals produced by electrowinning include copper, zinc, nickel, cobalt, manganese, and, in some processes, gold and silver.

Copper electrowinning uses a copper sulfate-sulfuric acid electrolyte; operation depends on current density, temperature, and solution purity to influence deposition rate and deposit quality. Impurities such as iron or nickel can affect conductivity and plating; membranes or diaphragms may be used to reduce cross-contamination between anode and cathode compartments. Energy consumption is a principal cost factor, and electrolyte management plus recycling of process streams are important design considerations.

Advantages of electrowinning include relatively high metal recovery and lower emissions compared with smelting. Limitations involve electrode wear, sensitivity to impurities, and the need for careful electrolyte control. The technology is a standard step in many hydrometallurgical flowsheets following leaching or solvent extraction.