This is a method of metal or metal compound extraction from an ore through pre-treatments that involve the use of a leaching agent, separation of impurities and precipitation. It is used in the extraction of uranium, gold, zinc, silver and copper from low-grade ores. This process has been improved by the development of processes like solvent extraction and ion exchange.
Hydrometallurgy involves the combination of extractive metallurgy, sciences, technology and chemistry for the recovery of metals from a wide variety of metal-bearing sources. These sources include ores, solutions, recycled materials, waste streams, intermediates and mineral concentrates that are converted into useful products for the society.
This wider field of technology is efficient in the on-site production of metals and forms an integral part of a growing number of metallurgical processes. It involves research, studies and novel technologies to obtain pure metals and better options for metal extraction. Hydrometallurgy revolves around three processes: leaching, metal recovery and solution purification.
The various techniques used in these processes include:
- Leaching – autoclave, column, atmospheric and pressure acid depending on the metal ore
- Recovery – carbon-in-leach and carbon-in-pulp, oxidation—biological or pressure method—and cementation
- Solution purification – ion-exchange, solvent extraction, electrowinning, precipitation and process simulations to determine flow sheet design