Hydrometallurgia

Hydrometallurgy is a branch of extractive metallurgy that uses aqueous chemistry to extract metals from ores, concentrates, and recycled materials. It covers processes that dissolve target metals, separate them from impurities, and recover them in pure or usable form. The core steps are leaching to produce a metal-bearing solution, purification and concentration of that solution, and recovery of the metal by precipitation, cementation, solvent extraction, ion exchange, or electrochemical methods such as electrowinning.

Leaching is the primary step and can use acids (commonly sulfuric or hydrochloric), bases, or bioleaching with microorganisms. Methods include heap leaching and vat leaching for low-grade ores, in-situ leaching for certain deposits, and controlled laboratory or pilot-scale leaching for process development.

Purification and separation remove impurities and concentrate the metal. Solvent extraction and ion exchange transfer metal ions from the leach solution into an organic phase or resin, followed by stripping to regain a purified aqueous phase. The final recovery may occur by precipitation, cementation, or electrolytic deposition, yielding metal metal or refined compounds.

Commonly produced metals include copper, nickel, cobalt, zinc, and uranium, with copper frequently recovered by solvent extraction–electrowinning (SX-EW). Gold and silver can be recovered from cyanide or thiosulfate leachates, while specialty metals come from various hydrometallurgical routes.

Advantages include lower temperature and energy use, suitability for low-grade or complex ores, and easier integration with recycling. Disadvantages concern chemical handling, effluent and residue management, and sensitivity to process economics and environmental regulation. Hydrometallurgy is often complementary to pyrometallurgy and increasingly important in sustainable metal supply chains.