Method for the hydrometallurgical recovery of lithium from the fraction of used galvanic cells containing lithium, iron and phosphate

Abstract

A method for the hydrometallurgical recovery of lithium from the fraction of used galvanic cells containing lithium, iron and phosphate is disclosed. According to the method, lithium-iron-phosphate-containing fraction is introduced into sulfuric acid and/or hydrochloric acid, and hydrogen peroxide is added in an amount that is at least stoichiometric relative to the iron content to be oxidized of the lithium-iron-phosphate-containing fraction.

Claims

1. A method for the hydrometallurgical recovery of lithium from a lithium-iron-phosphate-containing fraction of used galvanic cells comprising the steps of: introducing the lithium-iron-phosphate-containing fraction having an aluminum content of up to 5% by weight, and having a particle size of up to 500 m, into sulfuric acid having a concentration of 0.5 to 3 mol/l in an amount that is at least stoichiometric relative to the lithium content of the lithium-iron-phosphate-containing fraction and in a solid-to-liquid ratio in the range of 100 to 750 g/l; and solubilizing the lithium contained in the lithium-iron-phosphate-containing fraction at temperatures of between 25-70 C. with addition of hydrogen peroxide in an amount that is at least stoichiometric relative to the iron content of the lithium-iron-phosphate-containing fraction, wherein a lithium sulfate solution is formed; separating the lithium sulfate solution from a remaining residue; and washing the remaining residue at least twice, wherein a wash solution containing lithium sulfate is formed; wherein the separated lithium sulfate solution and the wash solution containing lithium sulfate are combined and are converted to lithium hydroxide by means of electrodialysis with bipolar membranes.

2. A method for the hydrometallurgical recovery of lithium from a lithium-iron-phosphate-containing fraction of used galvanic cells, comprising: introducing the lithium-iron-phosphate-containing fraction having an aluminum content of up to 5% by weight, and having a particle size of up to 500 m, into hydrochloric acid having a concentration of 0.5 to 3 mol/l in an amount that is at least stoichiometric relative to the lithium content of the lithium-iron-phosphate-containing fraction and in a solid-to-liquid ratio in the range of 50 to 450 g/l; and solubilizing the lithium contained in the lithium-iron-phosphate-containing fraction at temperatures of between 30-70 C. with addition of hydrogen peroxide in an amount that is at least stoichiometric relative to the iron content of the lithium-iron-phosphate-containing fraction, wherein a lithium chloride solution is formed; separating the lithium chloride solution from a remaining residue; and washing the remaining residue at least twice, wherein a wash solution containing lithium chloride is formed; wherein the separated lithium chloride solution and the wash solution containing lithium chloride are combined and are converted to lithium hydroxide by means of electrodialysis with bipolar membranes.

3. The method according to claim 1, wherein the aluminum content of the lithium-iron-phosphate-containing fraction is up to 3 wt. %.

4. The method according to claim 2, wherein the aluminum content of the lithium-iron-phosphate-containing fraction is up to 3 wt. %.

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

6. The method according to claim 3, wherein a content of multivalent metal cations is reduced by means of an ion exchanger.

7. The method according to claim 4, wherein a content of multivalent metal cations is reduced by means of an ion exchanger.

8. The method according to claim 1, wherein the lithium-iron-phosphate-containing fraction has a particle size of up to 150 m.

9. The method according to claim 2, wherein the lithium-iron-phosphate-containing fraction has a particle size of up to 50 to 400 m.

10. The method according to claim 1, wherein the sulfuric acid is used in a concentration of 0.75 to 2.5 mol/l.

11. The method according to claim 2, wherein the hydrochloric acid is used in a concentration of 0.75 to 2.5 mol/l.

12. The method according to claim 1, wherein the solid-to-liquid ratio is adjusted in the range of 150 to 650 g/l.

13. The method according to claim 2, wherein the solid-to-liquid ratio is adjusted in the range of 80 to 400 g/l.

14. The method according to claim 1, wherein the solubilizing step is carried out at temperatures of from 30 to 65 C.

15. The method according to claim 2, wherein the solubilizing step is carried out at temperatures of from 35 to 65 C.

16. The method according to claim 1, wherein the remaining residue is washed at least three times.

17. The method according to claim 2, wherein the remaining residue is washed at least three times.

18. The method according to claim 1, wherein the sulfuric acid and/or the hydrogen peroxide are/is used in excess.

19. The method according to claim 1, wherein the hydrochloric acid and/or the hydrogen peroxide are/is used in excess.

20. The method according to claim 18, wherein an excess of 0.1 to 10 mol % of the hydrochloric acid and/or the hydrogen peroxide is used.

21. The method according to claim 19, wherein an excess of 0.1 to 10 mol % of the hydrochloric acid and/or the hydrogen peroxide is used.

Description

(1) The process according to the invention is generally described hereinafter.

EXAMPLES

(2) The invention is explained in the case of the use of sulphuric acid with the aid of the following examples and Table 1.

(3) Under the conditions specified in Table 1, in each case 5 experiments were carried out with two different lithium-iron-phosphate-containing fractions.

(4) A lithium-iron-phosphate-containing fraction was used in Experiments 1-5, which was obtained from cathodes not installed in batteries. For experiments 6 to 10 a lithium-iron-phosphate-containing fraction from batteries was used. Hydrogen peroxide in excess of 5 mol % was used as oxidizing agent.

(5) TABLE-US-00001 TABLE 1 Test S/L c(H.sub.2SO.sub.4) Process Li Fe P number [g/l] excess conditions [%] [%] [%] 1 488 2M 6 h, 91.6 1.3 0.6 5 mol % 60 C. 2 270 1M 6 h, 95.8 0.3 1.1 5 mol % 60 C. 3 270 1M 5 h, 97.8 0.2 0.8 5 mol % 55 C. 4 488 2M 5 h, 91.6 1.8 0.7 5 mol % 55 C. 5 270 1M 5 h, >99 6.0 7.6 5 mol % 60 C. 6 270 1M 5 h, >99 5.5 6.7 5 mol % 60 C. 7 270 1M 5 h, >99 4.0 5.5 5 mol % 60 C. 8 270 1M 7 h, >99 4.0 6.6 5 mol % 60 C. 9 270 1M 5 h, >99 6.4 7.5 5 mol % 60 C. 10 488 2M 5 h, >99 12.5 13.4 5 mol % 55 C.

(6) The invention is explained in the case of the use of hydrochloric acid by means of the following examples and Table 2.

(7) Under the conditions specified in Table 2, in each case 8 tests with two different lithium-iron-phosphate-containing fractions were carried out. Tests 11 to 14 were executed with a lithium-iron-phosphate-containing fraction, which was obtained from cathodes not installed in batteries. For tests 15 to 18, a fraction containing lithium-iron-phosphate from batteries was used.

(8) Hydrogen peroxide was used as oxidizing agent at the specified excess.

(9) TABLE-US-00002 TABLE 1 Test S/L c(HCL) c(H.sub.2SO.sub.4) Process Li Fe P number [g/l] excess excess conditions [%] [%] [%] 11 300 2M without 5 h, 36.0 26.6 26.2 5 mol % H.sub.2O.sub.2 40 C. 12 300 2M without 5 h, 37.5 27.9 24.4 5 mol % H.sub.2O.sub.2 40 C. 13 270 2M 30 wt. % 24 h, 53.4 2.1 0.1 5 mol % 20 mol % 25 C. 14 270 2M 30 wt. % 1 h, 100 0.5 0.3 5 mol % 20 mol % 40 C. 15 270 2M 30 wt. % 5 h, 100 0.9 0.4 5 mol % 20 mol % 40 C. 16 270 2M 30 wt. % 5 h, 88.8 31.5 29.0 5 mol % 20 mol % 40 C. 17 270 2M 30 wt. % 5 h, 100 18.4 17.4 5 mol % 20 mol % 40 C. 18 270 2M 30 wt. % 5 h, 84.0 11.8 11.0 5 mol % 20 mol % 40 C.