Process for extracting a metal of interest from a mineral substrate
A method for extracting a metal of interest from a mineral substrate comprising: 1) providing a mineral substrate containing a metal of interest, 2) contacting the mineral substrate with a leaching medium comprising a pH reducing microorganism and/or an acid or proton produced by a pH reducing microorganism, and 3) recovering a leachate comprising the metal of interest.
1 . A method for extracting a metal of interest from a mineral substrate comprising:
1) providing a mineral substrate containing a metal of interest,
2) contacting the mineral substrate with a leaching medium comprising a pH reducing microorganism and/or an acid or proton produced by a pH reducing microorganism, and
3) recovering a leachate comprising the metal of interest,
wherein:
A) the metal of interest is present in the mineral substrate at a level of 5% by weight or less,
B) the metal of interest is a group I or group II metal, and/or
C) the microorganism produces one or more dicarboxylic acids which is present in the leaching medium.
2 . The method of claim 1 , wherein the microorganism produces oxalic acid, malonic acid and/or succinic acid.
3 . The method of claim 1 , wherein the leaching medium comprises the pH reducing microorganism.
4 . The method of claim 1 , wherein the leaching medium comprises an acid or proton produced by a pH reducing microorganism.
5 . The method of claim 1 , wherein the leaching medium comprises an acid or proton produced by a pH reducing microorganism, but does not comprise the pH reducing microorganism.
6 . The method of claim 1 , wherein the pH reducing microorganism produces citric acid, gluconic acid, sulphuric acid, oxalic acid, ascorbic acid, fumaric acid, acetic acid, propionic acid, butyric acid, isobutyric acid, succinic acid, formic acid, malonic acid, tartaric acid, itaconic acid and/or lactic acid.
7 . The method of claim 1 , wherein the acid or protons produced by the pH reducing microorganism reduces the pH of the leaching medium to pH 3 or less.
8 . The method of claim 1 , wherein the pH reducing microorganism is a bacteria or a fungus.
9 . The method of claim 1 , wherein the metal of interest is lithium and/or magnesium.
10 . The method of claim 1 , wherein the group I and/or II metal is lithium.
11 . The method of claim 1 , wherein the metal of interest is present in the mineral substrate at a level of 1% by weight or less.
12 . The method of claim 1 , wherein the metal of interest is recovered in the leachate in dissolved form.
13 . The method of claim 1 , wherein the mineral substrate is a clay.
14 . The method of claim 1 , further comprising the step of pre-treating the mineral substrate prior to being contacted with the leaching medium.
15 . The method of claim 14 , wherein the step of pre-treating the mineral substrate comprises washing the mineral substrate with a weak acid.
16 . The process of claim 15 , wherein the weak acid is oxalic acid.
17 . The method of claim 1 , wherein the metal of interest recovered in the leachate is post-treated.
18 . The method of claim 1 , wherein the metal of interest is present in the recovered leachate in the form of a metal dicarboxylate.
19 . The process of claim 18 , further comprising the step of converting the recovered metal dicarboxylate to metal carbonate.
20 . The method of claim 19 , wherein the recovered metal dicarboxylate is converted to metal carbonate by heat treatment or by reaction with alkali metal carbonate.