Hydrometallurgy is the branch of metallurgy that covers the extraction and recovery of metals using liquid, aqueous and organic solutions.
It is based on the concentration of solutions in one to several elements of metal interest, present as ions, that by reversible reactions and physical differences of the solutions are separated and isolated in a specific way. As a result, a rich solution is obtained in the ion of interest and with favorable characteristics for the next productive stage.
In general, the metals extracted by this technique are from minerals previously leached in sulphate, chloride, ammoniacal media, etc. Metals such as copper, nickel, vanadium, chromium and uranium are extracted in this way. For that last metal, Hydrometallurgy was started during the boom of the nuclear industry supported economically by the Second War and then the Cold War.
Hydrometallurgical processes normally operate at low temperatures (in the range of 25 to 250 ° C). Operating pressures can vary from a few kPa (kilopascals) (vacuum) to pressures as high as 5000 kPa.
The strong point of hydrometallurgy lies in the great variety of techniques and combinations that can be used to separate metals once they have been dissolved in the form of ions in aqueous solution.
The most important hydrometallurgical process is casting, whereby the desired mineral is selectively dissolved, although leaching and bioleaching processes are also common in contemporary metallurgy.
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