Principles of hydrometallurgy

Hydrometallurgy consists of a series of chemical processes characterized by the dissolution of a metal and its recovery from that solution. It primarily involves the following steps, which are separated by solid-liquid separation processes in some cases:

• leaching: the dissolution of metal into solution;

• purification: the removal of impurities other than the desired metal from a solution;

• production of the desired metal.

Purification of the solution is not always necessary if the ore or waste being processed contains few or no soluble impurities. In many cases, refining of the produced metal is essential in order to process the metal into a marketable form (ingots, metal salts, etc.). After the metal has been processed, the solution is generally...