ABSTRACT
Hydrometallurgical processing involves the use of aqueous media, such as acids, alkalis and organic solvents, in the extraction of metals from metal-bearing resources. These processes consist of a classic number of steps commonly known as unit processes. These include (1) leaching for the purpose of metal extraction into solution, (2) purification of the leach liqour to remove impurities, (3) concentration of the leach liquor to upgrade the metal content and finally, (4) recovery of the solid metal in different forms to be sold to the end market. The initial leaching step of getting the metal into solution is common for most of the material processed via a hydrometallurgical route. This is then followed by techniques such as solvent extraction (SX), ion exchange, adsorption, precipitation, chemical and gaseous reduction and electroreduction. The techniques generate two product streams: one containing value materials and the second a potential recycle in the process or a discharge stream.
