A process for producing battery-grade lithium carbonate from lithium-sodium-containing wastewater in ternary lithium batteries.

Abstract

This invention relates to the field of lithium extraction technology and proposes a process for producing battery-grade lithium carbonate from lithium-containing sodium wastewater in ternary batteries. The process includes the following steps: S1, adding activated carbon to the lithium-containing sodium wastewater and mixing to obtain a pretreatment solution; S2, adding an extractant to the pretreatment solution and mixing, followed by a first post-treatment to precipitate lithium, obtaining a lithium precipitation slurry and a lithium precipitation mother liquor; S3, performing a second post-treatment on the lithium precipitation slurry to obtain battery-grade lithium carbonate. In step S2, the extractant includes 2-ethylhexyl phosphate (2-ethylhexyl ester) and 1-ethyl methyl-3-methylimidazolium tetraborate. This technical solution solves the problem of low yield in related technologies when extracting lithium carbonate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium extraction, in particular to a process for producing battery-grade lithium carbonate from lithium-sodium-containing wastewater solution recovered from ternary batteries. BACKGROUND

[0002] A large number of used and scrapped ternary batteries need to be safely, environmentally and efficiently treated every year. Therefore, the process for producing battery-grade lithium carbonate from lithium-sodium-containing wastewater solution recovered from ternary batteries is widely studied. The solvent extraction method in the existing lithium extraction process has the advantages of simple operation, high efficiency and low cost, and has been rapidly researched and developed in the field of lithium extraction. However, there are still defects such as insufficient lithium extraction effect and low lithium carbonate yield. Therefore, it is necessary to develop a production process for improving the yield of lithium carbonate to promote the recycling of ternary battery wastewater solution. SUMMARY

[0003] The present application provides a process for producing battery-grade lithium carbonate from lithium-sodium-containing wastewater solution recovered from ternary batteries, which solves the problem of low yield in the related art when extracting lithium carbonate.

[0004] The technical scheme of the present application is as follows:

[0005] The present application provides a process for producing battery-grade lithium carbonate from lithium-sodium-containing wastewater solution recovered from ternary batteries, which includes the following steps:

[0006] S1, adding activated carbon to the lithium-sodium-containing wastewater solution and mixing to obtain a pretreated solution;

[0007] S2, adding an extractant to the pretreated solution and mixing, and after first post-treatment, lithium is precipitated to obtain lithium precipitation slurry and lithium precipitation mother liquor;

[0008] S3, second post-treatment of the lithium precipitation slurry to obtain battery-grade lithium carbonate;

[0009] In step S2, the extractant includes 2-ethylhexyl 2-ethylhexyl phosphate and 1-ethyl methyl-3-methyl imidazole tetrafluoroborate.

[0010] As a further technical solution, the mass ratio of 2-ethylhexyl 2-ethylhexyl phosphate and 1-ethyl methyl-3-methyl imidazole tetrafluoroborate is 3:2~4:1.

[0011] In the present application, by adjusting the mass ratio of 2-ethylhexyl 2-ethylhexyl phosphate and 1-ethyl methyl-3-methyl imidazole tetrafluoroborate to 3:2~4:1, the yield of battery-grade lithium carbonate produced from lithium-sodium-containing wastewater solution recovered from ternary batteries is further improved.

[0012] As a further technical solution, in step S1, the mixing time is 40-50 min; in step S2, the mixing time is 60-90 min.

[0013] As a further technical solution, the first post-treatment comprises evaporation concentration, continuous flash evaporation and freeze crystallization, alkali impurity removal, and resin column filtration treatment in sequence; and the second post-treatment comprises filtration, washing, drying, and crushing treatment in sequence.

[0014] As a further technical solution, the alkali impurity removal is performed at a temperature of 80-90℃, a pH of 11-12, and for a time of 30-60 min.

[0015] As a further technical solution, the resin type in the resin column is one or more of LS-1000, CH-93, CH-90, and LSC-500.

[0016] As a further technical solution, the resin type in the resin column is one or both of CH-90 and LSC-500.

[0017] In the present application, the resin column is used to adsorb calcium and magnesium ions, and especially when the resin type of the resin column is CH-90 or LSC-500, the purity of the battery-grade lithium carbonate produced from the lithium-sodium-containing wastewater solution recovered from the ternary battery can be further improved.

[0018] As a further technical solution, the lithium precipitation mother liquor can be mixed with sulfuric acid for acidification, the pH value is controlled to be 2-4, the acidification reaction time is greater than 30 min, then liquid caustic is added for pH adjustment, the pH value is controlled to be 7-8, and the mixed solution containing lithium and sodium after acidification can be returned to the raw material section for recycling.

[0019] As a further technical solution, the particle size of the battery-grade lithium carbonate is 4-6 μm.

[0020] As a further technical solution, sodium carbonate is added during lithium precipitation and reacted at 90-95℃ for 3-4 h.

[0021] The working principle and beneficial effects of the present application are as follows:

[0022] In the present application, 2-ethylhexyl phosphoric acid 2-ethylhexyl ester and 1-ethyl methyl-3-methyl imidazole tetrafluoroborate are used together as extractants to extract lithium carbonate, and the two synergistically improve the yield of battery-grade lithium carbonate produced from the lithium-sodium-containing wastewater solution recovered from the ternary battery. DETAILED DESCRIPTION

[0023] With reference to the drawings and embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0024] Embodiment 1

[0025] A process for producing battery-grade lithium carbonate from a lithium-sodium-containing wastewater solution in a ternary battery, comprising the following steps:

[0026] S1, adding activated carbon to the lithium-sodium-containing wastewater solution and mixing for 40 min to obtain a pretreated solution;

[0027] S2, adding 200 mL of an extractant to 500 mL of the pretreated solution and mixing for 60 min, then performing evaporation concentration, continuous flash evaporation and freeze crystallization, alkali impurity removal (at 90°C and pH 11 for 30 min), resin column filtration treatment with a resin column containing CH-93 resin, and then adding sodium carbonate and reacting at 90°C for 4 h to precipitate lithium, to obtain a lithium precipitation slurry and a lithium precipitation mother liquor; the lithium precipitation mother liquor can be mixed with sulfuric acid for acidification, the pH value is controlled at 2, the acidification reaction time is 50 min, then liquid alkali is added for pH adjustment, the pH value is controlled at 8, and the mixed solution containing lithium and sodium after acidification can be returned to the raw material section for recycling;

[0028] S3, after the lithium precipitation slurry is subjected to filtration, washing and drying three-in-one treatment, it is crushed to obtain battery-grade lithium carbonate with a particle size of 5 μm; wherein the extractant is 2-ethylhexyl phosphoric acid 2-ethylhexyl ester and 1-ethyl ester methyl-3-methyl imidazole tetrafluoroborate with a mass ratio of 1:4;

[0029] Calculation and detection show that the yield of lithium carbonate is 97.8% and the purity is 99.0%.

[0030] Embodiment 2

[0031] A process for producing battery-grade lithium carbonate from a lithium-sodium-containing wastewater solution in a ternary battery, comprising the following steps:

[0032] S1, adding activated carbon to the lithium-sodium-containing wastewater solution and mixing for 50 min to obtain a pretreated solution;

[0033] S2, 400 mL of the extractant is added to 500 mL of the pretreated solution and mixed for 90 min, concentrated by evaporation, continuously flashed and frozen crystallized, treated by alkali removal impurity (removed at 80 DEG C, pH 12 for 60 min), filtered by a resin column containing resin with model CH-93, then sodium carbonate is added to react and precipitate lithium at 95 DEG C for 4 h to obtain a lithium precipitation slurry and a lithium precipitation mother liquor; the lithium precipitation mother liquor can be mixed with sulfuric acid for acidification, the pH value is controlled to be 4, the acidification reaction time is 60 min, then liquid alkali is added to adjust the pH value to 7, and the mixed solution containing lithium sodium after acidification can be returned to the raw material section for recycling;

[0034] S3, after the lithium precipitation slurry is treated by filtration, washing and drying in one step, it is crushed to obtain battery-grade lithium carbonate with a particle size of 5 μm; wherein the extractant is 2-ethylhexyl phosphonic acid 2-ethylhexyl ester and 1-ethyl ester methyl-3-methyl imidazole tetrafluoroborate with a mass ratio of 1:4;

[0035] Through calculation and detection, the yield of lithium carbonate is 98.0%, and the purity is 99.0%.

[0036] Example 3

[0037] A process for producing battery-grade lithium carbonate from a wastewater solution containing lithium sodium in a ternary battery, comprising the following steps:

[0038] S1, active carbon is added to the wastewater solution containing lithium sodium and mixed for 45 min to obtain a pretreated solution;

[0039] S2, 300 mL of the extractant is added to 500 mL of the pretreated solution and mixed for 75 min, concentrated by evaporation, continuously flashed and frozen crystallized, treated by alkali removal impurity (removed at 90 DEG C, pH 11 for 50 min), filtered by a resin column containing resin with model CH-93, then sodium carbonate is added to react and precipitate lithium at 95 DEG C for 3 h to obtain a lithium precipitation slurry and a lithium precipitation mother liquor; the lithium precipitation mother liquor can be mixed with sulfuric acid for acidification, the pH value is controlled to be 3, the acidification reaction time is 60 min, then liquid alkali is added to adjust the pH value to 8, and the mixed solution containing lithium sodium after acidification can be returned to the raw material section for recycling;

[0040] S3, after the lithium precipitation slurry is treated by filtration, washing and drying in one step, it is crushed to obtain battery-grade lithium carbonate with a particle size of 5 μm; wherein the extractant is 2-ethylhexyl phosphonic acid 2-ethylhexyl ester and 1-ethyl ester methyl-3-methyl imidazole tetrafluoroborate with a mass ratio of 1:4;

[0041] Through calculation and detection, the yield of lithium carbonate is 98.2%, and the purity is 99.1%.

[0042] Example 4

[0043] The difference between this example and Example 3 is that the extractant is 2-ethylhexyl phosphonic acid 2-ethylhexyl ester and 1-ethyl methyl-3-methyl imidazole tetrafluoroborate in a mass ratio of 5:1.

[0044] The yield of lithium carbonate was calculated and measured to be 98.0% with a purity of 99.2%.

[0045] Example 5

[0046] The difference between this example and Example 3 is that the extractant is 2-ethylhexyl phosphonic acid 2-ethylhexyl ester and 1-ethyl methyl-3-methyl imidazole tetrafluoroborate in a mass ratio of 3:2.

[0047] The yield of lithium carbonate was calculated and measured to be 99.3% with a purity of 99.2%.

[0048] Example 6

[0049] The difference between this example and Example 3 is that the extractant is 2-ethylhexyl phosphonic acid 2-ethylhexyl ester and 1-ethyl methyl-3-methyl imidazole tetrafluoroborate in a mass ratio of 4:1.

[0050] The yield of lithium carbonate was calculated and measured to be 99.7% with a purity of 99.1%.

[0051] Example 7

[0052] The difference between this example and Example 6 is that the resin with model CH-93 is replaced by the resin with model LS-1000.

[0053] The purity of lithium carbonate was measured to be 99.2%.

[0054] Example 8

[0055] The difference between this example and Example 6 is that the resin with model CH-93 is replaced by the resin with model CH-90.

[0056] The purity of lithium carbonate was measured to be 99.6%.

[0057] Example 9

[0058] The difference between this example and Example 6 is that the resin with model CH-93 is replaced by the resin with model LSC-500.

[0059] The purity of lithium carbonate was measured to be 99.8%.

[0060] Comparative Example 1

[0061] The difference between this comparative example and Example 3 is that the extractant is 2-ethylhexyl phosphonic acid 2-ethylhexyl ester;

[0062] The yield of lithium carbonate was calculated and detected to be 94.0%.

[0063] Comparative Example 2

[0064] The difference between the present comparative example and Example 3 is that the extractant is 1-ethyl-methyl-3-methylimidazole tetrafluoroborate;

[0065] The yield of lithium carbonate was calculated and detected to be 93.5%.

[0066] Comparative Example 3

[0067] The difference between the present comparative example and Example 3 is that the extractant is tributyl phosphate and 1-ethyl-methyl-3-methylimidazole tetrafluoroborate;

[0068] The yield of lithium carbonate was calculated and detected to be 91.6%.

[0069] Comparative Example 4

[0070] The difference between the present comparative example and Example 3 is that the extractant is 2-ethylhexyl phosphoric acid 2-ethylhexyl ester and 1-ethyl-3-vinylimidazole acetate;

[0071] The yield of lithium carbonate was calculated and detected to be 92.2%.

[0072] By comparing the data of Examples 1-9 and Comparative Examples 1-4, it can be found that the yield of lithium carbonate obtained by Examples 1-9 is higher than that of Comparative Examples 1-4, which indicates that using 2-ethylhexyl phosphoric acid 2-ethylhexyl ester and 1-ethyl-methyl-3-methylimidazole tetrafluoroborate as the extractant for extracting lithium carbonate can significantly improve the yield of producing battery-grade lithium carbonate from the lithium-sodium-containing wastewater solution recovered from ternary batteries.

[0073] By comparing the data of Examples 3-6, it can be found that the yield of lithium carbonate obtained by Examples 5-6 is higher than that of Examples 3-4, which indicates that by adjusting the mass ratio of 2-ethylhexyl phosphoric acid 2-ethylhexyl ester and 1-ethyl-methyl-3-methylimidazole tetrafluoroborate to 3:2-4:1, the yield of producing battery-grade lithium carbonate from the lithium-sodium-containing wastewater solution recovered from ternary batteries is further improved.

[0074] By comparing the data of Examples 6-9, it can be found that the purity of lithium carbonate obtained by Examples 8-9 is higher than that of Examples 6-7, which indicates that using a resin column to adsorb calcium and magnesium ions, especially when the resin type of the resin column is CH-90 or LSC-500, can further improve the purity of producing battery-grade lithium carbonate from the lithium-sodium-containing wastewater solution recovered from ternary batteries.

[0075] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for producing battery grade lithium carbonate from a lithium sodium containing wastewater solution recovered in a ternary battery, characterized by, The method comprises the following steps: S1, adding activated carbon into a wastewater solution containing lithium sodium and mixing to obtain a pretreated solution; S2, adding an extractant into the pretreated solution and mixing, performing first post-treatment, and precipitating lithium to obtain a lithium precipitation slurry and a lithium precipitation mother liquor; S3, performing second post-treatment on the lithium precipitation slurry to obtain battery-grade lithium carbonate. In step S2, the extractant comprises 2-ethylhexyl 2-ethylhexyl phosphonate and 1-ethyl methyl-3-methyl imidazole tetrafluoroborate.

2. A process for the production of battery grade lithium carbonate from a lithium sodium containing wastewater solution recovered in a lithium ion battery, according to claim 1, characterized in that, The mass ratio of the 2-ethylhexyl 2-ethylhexyl phosphonate and the 1-ethyl methyl-3-methyl imidazole tetrafluoroborate is 3:2-4:

1.

3. A process for the production of battery grade lithium carbonate from a lithium sodium containing wastewater solution recovered in a lithium ion battery, as claimed in claim 1, wherein, In step S1, the mixing time is 40-50 min; in step S2, the mixing time is 60-90 min.

4. A process for the production of battery grade lithium carbonate from a lithium sodium containing wastewater solution recovered in a lithium ion battery, as claimed in claim 1, wherein, The first post-treatment comprises evaporation and concentration, continuous flash and freezing crystallization, alkali impurity removal, and resin column filtration treatment in sequence; the second post-treatment comprises filtration, washing, drying, and crushing treatment in sequence.

5. A process for the production of battery grade lithium carbonate from a lithium sodium containing wastewater solution recovered in a lithium ion battery, according to claim 4, characterized in that, The alkali impurity removal is performed at a temperature of 80-90℃, a pH of 11-12, and a time of 30-60 min.

6. A process for the production of battery grade lithium carbonate from a lithium sodium containing wastewater solution recovered in a lithium ion battery, according to claim 4, characterized in that, The resin type in the resin column is one or more of LS-1000, CH-93, CH-90, and LSC-500.

7. A process for the production of battery grade lithium carbonate from a lithium sodium containing wastewater solution recovered in a lithium ion battery, according to claim 6, characterized in that, The resin type in the resin column is one or both of CH-90 and LSC-500.

8. A process for the production of battery grade lithium carbonate from a lithium sodium containing wastewater solution recovered in a lithium ion battery, as claimed in claim 1, wherein, The lithium precipitation mother liquor can be mixed with sulfuric acid for acidification, the pH value is controlled to be 2-4, the acidification reaction time is greater than 30 min, then liquid caustic is added for pH adjustment, the pH value is controlled to be 7-8, and the mixed solution containing lithium sodium after acidification can be returned to the raw material section for recycling.

9. A process for the production of battery grade lithium carbonate from a lithium sodium containing wastewater solution recovered in a lithium ion battery, as claimed in claim 1, wherein, The particle size of the battery-grade lithium carbonate is 4-6 μm.

10. A process for the production of battery grade lithium carbonate from a lithium sodium containing wastewater solution recovered in a lithium ion battery, as claimed in claim 1, wherein, Sodium carbonate is added when the lithium is precipitated, and the reaction is performed at 90-95℃ for 3-4 h.