Hydrometallurgy
Hydrometallurgy as a word is derived from the Greek hýdōr, meaning water. It refers to the technique of extracting metal from an ore or another material by creating an aqueous solution of a salt of the metal and then recovering the metal from the solution. It is an approach that uses both technology and chemistry to recover metals from a wide variety of metal-bearing sources, which include recycled materials, waste streams, intermediates, mineral concentrates, ores and other solutions.
Hydrometallurgy involves three processes:
- Leaching - which means to drain away from and involves various process such as autoclave, column, atmospheric and pressure acid depending on the metal ore.
- Recover - which refers to the extraction of previously processed metals by methods of carbon-in-leach, carbon-in-pulp, oxidation through a biological approach or using pressure and cementation.
- Solution purification - which refers to the physical separation of the metal from a solution through ion-exchange, direct solvent extraction, electrowinning, or precipitation (also classified as electrometallurgy).
It is a one of the three branches of metallurgy, with the others being pyrometallurgy and electrometallurgy. The three main types of pyrometallurgy might be considered as being calcination, roasting and smelting.
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