A
lixiviant is a
chemical used in
hydrometallurgy to extract elements from its
ore.
The term lixiviant can be somewhat obscure, as it is not mentioned in reviews of metallurgy.
Extraction of gold
One of the most famous lixiviants is
cyanide, which is used in
gold extraction. The combination of cyanide and the oxygen in air converts gold particles into a soluble salt. Once separated from the bulk
gangue, the solution is processed in a series of steps to give the metal.
A wide variety of less toxic alternatives to cyanide have been evaluated including
thioureas, thiocyanate]], and
thiosulfate. Several of these lixiviants are applicable to metals other than gold.
Dissolution of other metals
Typically lixiviants are applied to the extraction of ions of valuable metals from some processed form of an ore. Lixiviants are also used for the recovery of metals from wastes and scrap.
and
often contain platinum and other valuable metals. Some of the lixiviants that have been evaluated in such situations include:
aqua regia,
cyanide (as in gold extraction), hydrogen peroxide, and
iodide/
iodine.
Lixiviants have also been applied to the recycling of lithium ion batteries.
"Lixiviant systems" also refer to the dissolution of purified metals. The purpose of such a process is to produce for synthesis or for analysis. As for gold, the lixiviant must include an oxidant, which can include , and a Lewis base, which can be a thiourea.
Etymology
The origin is the word
, meaning to leach or to dissolve out, deriving from the Latin
lixivium.
[The New English Dictionary] A lixiviant assists in rapid and complete leaching, for example during in situ leaching. The metal can be recovered from it in a concentrated form after leaching.
See also
-
Cementation refers to processes that reverse the action of a lixiviant.
