Method of extracting lithium compound(s)

Patent metadata

Field	Value
Publication number	US-2021147247-A1
Application number	US-201716623015-A
Country	US
Kind code	A1
Filing date	Jun 22, 2017
Priority date	Jun 22, 2017
Publication date	May 20, 2021
Grant date	—

Abstract

A method and apparatus of preparing lithium compound(s) from lithium-containing mineral includes a) a leaching step, wherein the lithium-containing mineral is leached in aqueous leach solution containing alkaline carbonate, for liberating lithium and phosphate(s) from the lithium-containing mineral, thus obtaining leach slurry containing lithium carbonate and phosphate(s) leach slurry, b) a carbonization step, wherein the leach slurry containing lithium carbonate and phosphate(s), obtained from the leaching step, is reacted with an alkali earth metal compound in the presence of CO2 for obtaining a carbonated slurry containing lithium hydrogen carbonate, and for precipitating phosphate(s) contained in the leach slurry as insoluble phosphate compound(s), c) a solid-liquid separation step, wherein the carbonated slurry obtained from carbonization step is subjected to solid-liquid separation wherein the undissolved mineral and phosphate compound(s) are separated as solids that can be recovered or discarded, thereby obtaining a solution containing lithium hydrogen carbonate.

First claim

1 .- 15 . (canceled)

16 . A method of preparing one or more types of lithium compounds from lithium-containing mineral, wherein the method comprises:
a) a leaching step, wherein the lithium-containing mineral is leached in aqueous alkaline carbonate leach solution, for liberating lithium compounds and phosphate(s) from the lithium-containing mineral, thus obtaining a leach slurry containing lithium carbonate and phosphate(s), b) a carbonization step, wherein the obtained leach slurry is reacted with an alkali earth metal compound in the presence of CO 2 , for obtaining a carbonated slurry containing lithium hydrogen carbonate, and for precipitating phosphate(s) from the leach slurry as insoluble phosphate compound(s), c) a solid-liquid separation step, wherein the carbonated slurry obtained from the carbonization step is subjected to solid-liquid separation, wherein undissolved mineral and the insoluble phosphate compound(s) are separated as solids that can be recovered or discarded, thereby obtaining a solution containing lithium hydrogen carbonate.

17 . The method according to claim 16 , wherein the lithium containing mineral is used in the form of lithium-containing concentrate, typically spodumene concentrate.

18 . The method according to claim 16 , wherein the alkaline carbonate leach solution comprises sodium carbonate and/or potassium carbonate.

19 . The method according to claim 16 , wherein the leaching step is performed at elevated temperature and elevated pressure.

20 . The method according to claim 16 , wherein the temperature of the leaching step is 150° C. or more, typically between 150-300° C., more typically between 190-240° C.

21 . The method according to claim 16 , wherein the alkali earth metal compound is added before and/or during the leaching step and/or before and/or during the carbonization step.

22 . The method according to claim 16 , wherein the alkali earth metal compound is selected from the group consisting of alkali earth metal hydroxide(s), alkali earth metal carbonate(s), alkali earth metal hydrogen carbonate(s), and alkali earth metal chloride(s), typically the alkali earth metal compound is Mg(OH) 2 , typically in solid form.

23 . The method according to claim 16 , wherein the insoluble phosphate compound is alkali earth metal hydrogen phosphate, such as magnesium hydrogen phosphate or calcium hydrogen phosphate.

24 . The method according to claim 16 , wherein the carbonization step is performed at temperature between 0-50° C., typically between 15 to 40° C.

25 . The method according to claim 16 , wherein the solid-liquid separation step is performed by filtering, typically by vacuum belt filtering.

26 . The method according to claim 16 , wherein the method further comprises a crystallization step d), wherein the lithium hydrogen carbonate-containing solution is heated to decompose bicarbonate and to crystallize lithium carbonate.

27 . The method according to claim 16 , wherein the method is performed batch wise or continuously.

28 . The use of the method according to claim 16 for preparing lithium hydrogen carbonate, which optionally is crystallized to form lithium carbonate.

Assignees

• Outotec Finland Oy

Inventors

• Tiihonen Marika

Classifications

• Y02P10/20

  Recycling · CPC title

• C22B26/12 Primary

  Obtaining lithium · CPC title

• C01D15/08 Primary

  Carbonates; Bicarbonates · CPC title

• C22B3/44

  by chemical processes (treatment or purification of solutions by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42) · CPC title

• C01B32/60

  Preparation of carbonates or bicarbonates in general (of percarbonates C01B15/10; of specific carbonates or bicarbonates according to the cation C01B-C01G) · CPC title