Method for the hydrometallurgical recovery of lithium from the lithium manganese oxide-containing fraction of used galvanic cells

1. A method for hydrometallurgical recovery of lithium from a fraction of used galvanic cells containing lithium manganese oxide, the method comprising the steps of:

adding the fraction of used galvanic cells containing lithium manganese oxide with a particle size up to 500 μm to a hyper-stoichiometric amount of oxalic acid based on the manganese content in the lithium manganese oxide, wherein a 0.1 to 1.0 molar excess of oxalic acid is used, and is solubilized in a solid/liquid ratio in the range of 10 g/l to 250 g/l at a temperature in the range of 30° C. to 70° C. to form a lithium-containing solution;

separating the lithium-containing solution from a remaining residue; and

washing the remaining residue at least twice to form a washing solution containing lithium;

wherein the separated lithium-containing solution and the washing solution containing lithium are combined, a dissolved manganese residue content is reduced by precipitation as hydroxide, separated and washed, and a remaining lithium-containing solution is further purified by conversion into a carbonate, chloride or sulfate.

2. The method according to claim 1 , wherein a content of multivalent metal cations is reduced using an ion exchanger.

3. The method according to claim 1 , wherein the fraction of used galvanic cells containing lithium manganese oxide has a particle size of 100 μm to 400 μm.

4. The method according to claim 2 , wherein the fraction of used galvanic cells containing lithium manganese oxide has a particle size of 100 μm to 400 μm.

5. The method according to claim 1 , wherein the oxalic acid is used at a concentration of 0.2 mol/l to 1.2 mol/l.

6. The method according to claim 2 , wherein the oxalic acid is used at a concentration of 0.2 mol/l to 1.2 mol/l.

7. The method according to claim 1 , wherein the oxalic acid is used at a concentration of 0.5 mol/l to 1.0 mol/l.

8. The method according to claim 1 , wherein the solid to liquid ratio is adjusted in the range of 20 g/l to 200 g/l.

9. The method according to claim 1 , wherein in the solubilization step, the temperature is in the range of 35° C. to 65° C.

10. The method according to claim 1 , wherein in the washing step, the remaining residue is washed at least three times.

11. The method according to claim 1 , wherein the oxalic acid is used in a molar excess of from 0.2 to 0.8.

12. The method according to claim 1 further comprising the step of crystalizing the carbonate, chloride, or sulfate.

13. The method according to claim 1 , wherein in the solubilization step the temperature is in the range of 40° C. to 60° C.

14. The method according to claim 1 , wherein the solid to liquid ratio is adjusted in the range of 45 g/l to 90 g/l.

15. A method comprising the steps of:

(A) contacting a fraction of used galvanic cells containing lithium manganese oxide with oxalic acid, wherein the fraction containing lithium manganese oxide has a particle size up to 500 μm and a mole ratio of lithium manganese oxide to oxalic acid is in the range of from 1:4 to 1:4.5;

(B) solubilizing the lithium contained in the fraction containing lithium manganese oxide at a solid/liquid ratio in the range of 10 g/l to 250 g/l at a temperature in the range of 30° C. to 70° C. to form a lithium-containing solution;

(C) separating the lithium-containing solution from a remaining residue;

(D) washing the remaining residue at least twice to form a washing solution containing lithium;

(E) combining the lithium-containing solution from step (C) and the washing solution containing lithium from step (D) to form a combined solution containing lithium;

(F) reducing a dissolved manganese residue content in the combined solution containing lithium by precipitation of manganese hydroxide;

(G) separating the precipitated manganese hydroxide from the combined solution containing lithium to form a remaining lithium-containing solution; and

(H) purifying the remaining lithium-containing solution by conversion into lithium carbonate, lithium chloride or lithium sulfate;

wherein heat is supplied by reaction heat in step (B), without an additional heat source, and the temperature is controlled by regulating the mole ratio of lithium manganese oxide to oxalic acid.

16. The method of claim 1 , wherein in the solubilizing step heat is supplied by reaction heat, without an additional heat source, and the temperature is controlled regulating a mole ratio of lithium manganese oxide to oxalic acid.

17. The method of claim 15 further comprising washing the precipitated manganese hydroxide.