Methods for treating lithium-containing materials
The present disclosure relates to a method for extracting lithium from a lithium-containing material. For example, the method can comprise leaching a roasted lithium-containing material under conditions suitable to obtain an aqueous composition comprising a lithium compound such as lithium sulfate and/or lithium bisulfate. The aqueous composition comprising lithium sulfate and/or lithium bisulfate can optionally be used, for example, in a method for preparing lithium hydroxide comprising an electromembrane process. The roasted lithium-containing material can be prepared, for example by a method which uses an aqueous composition comprising optionally lithium sulfate and/or lithium bisulfate which can be obtained from a method for preparing lithium hydroxide comprising an electromembrane process such as a two-compartment monopolar or bipolar electrolysis process.
1. A method for preparing lithium hydroxide, said method comprising:
submitting a first aqueous composition comprising lithium sulfate to an electromembrane process under suitable conditions for at least partial conversion of said lithium sulfate into lithium hydroxide and to obtain a second aqueous composition comprising lithium sulfate; and
increasing concentration of acid in said second aqueous composition; and
using said second aqueous composition comprising lithium sulfate for reacting with a lithium-containing material.
2. The method of claim 1 , wherein said method further comprises recovering lithium sulfate from said second aqueous composition and reusing said lithium sulfate in said electromembrane process.
3. The method of claim 1 , wherein said method further comprises at least partially recovering lithium sulfate from said second aqueous composition, before using said second aqueous composition for reacting with said lithium-containing material, and reusing said lithium sulfate in said electromembrane process.
4. The method of claim 1 , wherein said method comprises increasing concentration of acid in said second aqueous composition by removing water from said second aqueous composition.
5. The method of claim 4 , wherein increasing concentration of said acid is carried out by heating said second aqueous composition.
6. The method of claim 5 , wherein said second aqueous composition is heated at a temperature of about 100° C. to about 300° C.
7. The method of claim 5 , wherein said second aqueous composition is heated at a temperature of about 110° C. to about 130° C.
8. The method of claim 5 , wherein said second aqueous composition is heated at a temperature of about 115° C. to about 125° C.
9. The method of claim 6 , wherein said second aqueous composition is heated at below atmospheric pressure or under vacuum.
10. The method of claim 4 , wherein increasing concentration of said acid is carried out by a membrane dehydration process, by a reverse osmosis membrane process or by adding some acid.
11. The method of claim 4 , wherein removing water from said second aqueous composition causes precipitation of lithium sulfate monohydrate.
12. A method for preparing lithium hydroxide, said method comprising:
submitting a first aqueous composition comprising lithium sulfate to an electromembrane process under suitable conditions for at least partial conversion of said lithium sulfate into lithium hydroxide and to obtain a second aqueous composition comprising lithium sulfate; and
increasing concentration of acid in said second aqueous composition; and
recovering lithium sulfate from said second aqueous composition and reusing it for the electromembrane process.