An extraction system for extracting lithium from lithium-containing brine and its application

Abstract

The present invention provides an extraction system for extracting lithium from lithium-containing brine and its application. The extraction system includes an extractant and a co-extractant. The extractant is a trialkyl neutral phosphate containing a benzene ring, including any one or a combination of at least two of triphenyl phosphate, phenyl ditolyl phosphate, tricresyl phosphate, diphenyl isooctyl phosphate, monophenyl diisooctyl phosphate, triisopropylphenyl phosphate, or phenyl (di-tert-butylphenyl) phosphate, and the co-extractant includes ferric chloride. The extraction system provided by the present invention has the advantages of high selectivity, low water solubility, strong stability, and good extraction effect. It can reduce pollution to the environment, reduce costs, and has good industrial application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical separation, and specifically relates to an extraction system for extracting lithium from lithium-containing brine and its application, and more particularly to an extraction system for extracting lithium from lithium-containing brine with high selectivity and its application. Background Art

[0002] In recent years, with the rapid development of new energy vehicles, electronic devices, and energy storage technologies, lithium's application in new energy materials has garnered significant attention, leading to a surge in both consumption and demand. Global automotive lithium carbonate demand was projected to reach 312,000 tons in 2021 and 864,000 tons in 2025. Lithium resources are primarily found in salt lake brines and ores. However, the similar properties of lithium and magnesium make separation difficult, making lithium resource development challenging.

[0003] Currently, there is a method for extracting lithium from high-magnesium salt lake brine using a solvent extraction system with TBP (tributyl phosphate) and neutral phosphate esters with alkyl chains as aliphatic hydrocarbons as the main extractants. The lithium-magnesium separation coefficient (β Li / Mg ) is about 50-100, the lithium-calcium separation coefficient (β Li / Ca ) is only about 0.5. Due to the poor separation of Mg and Ca, after obtaining a lithium-rich stripping solution, precipitation and other processes are often added to further remove impurities such as calcium and magnesium to obtain a higher-purity lithium product. Similarly, the use of solvent extraction to extract lithium from low-chloride, high-calcium and magnesium salt lake brines in South America also requires the addition of a stripping solution impurity removal process to obtain a high-purity lithium product.

[0004] CN104404269A discloses an organic phase for extracting lithium, comprising a composite extractant made of tributyl phosphate and N,N-di(2-ethylhexyl)-3-butanone acetamide. The system can extract lithium from a saturated magnesium chloride solution in the presence of FeCl3, but the back extraction process requires hydrochloric acid back extraction, and the organic phase needs to consume alkali for regeneration. CN107502741A discloses a composite extraction system and extraction method for extracting lithium from lithium-containing brine. The composite system is composed of a loaded FeCl3 and a 2-ethylhexyl-3-butanone acetamide. 3+ The above two composite extraction systems are complex in composition and require impurity removal to obtain a high-purity lithium product. The separation effect of Ca and Mg (especially Ca separation) needs to be further improved. At the same time, the above extraction systems are prone to problems such as system emulsification and extraction agent degradation after long-term operation, resulting in severe extraction agent dissolution.

[0005] Therefore, it is of great significance to develop a new type of highly selective extractant to separate Li from a large amount of Na, K, Ca, Mg, etc. in one step to obtain a Li-rich strip solution that can be used to directly prepare high-purity lithium products. Summary of the Invention

[0006] To address the shortcomings of the prior art, the present invention aims to provide an extraction system for extracting lithium from lithium-containing brines and its applications, particularly to provide a highly selective extraction system for extracting lithium from lithium-containing brines and its applications. The extraction system provided by the present invention has the advantages of high selectivity, low water solubility, strong stability, and excellent extraction efficiency. It can reduce environmental pollution and lower costs, and has promising industrial application prospects.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] On the one hand, the present invention provides an extraction system for extracting lithium from lithium-containing brine, the extraction system comprising an extractant and a co-extractant, the extractant being a trialkyl neutral phosphate containing a benzene ring, including any one or a combination of at least two of triphenyl phosphate, phenyl ditolyl phosphate, tricresyl phosphate, diphenyl isooctyl phosphate, monophenyl diisooctyl phosphate, triisopropylphenyl phosphate or phenyl (di-tert-butylphenyl) phosphate, and the co-extractant comprising ferric chloride.

[0009] The above-mentioned extraction system uses a trialkyl neutral phosphate containing a benzene ring as an extractant, which can effectively affect the extraction effect of calcium ions and magnesium ions, and has almost no effect on the extraction of lithium ions, thereby effectively improving the selectivity of the extraction. It has the advantages of high selectivity, low water solubility, strong stability, and good extraction effect. It can reduce pollution to the environment, reduce costs, and has good industrial application prospects.

[0010] Preferably, the extractant is a combination of triphenyl phosphate, tricresyl phosphate and diphenyl isooctyl phosphate.

[0011] The above-mentioned three specific extraction agents are compounded and work synergistically, which can further improve the selectivity of the extraction results compared with other extraction agents.

[0012] Preferably, the extraction system further comprises a diluent, and the diluent comprises any one or a combination of at least two of aromatic hydrocarbons, ester compounds, aliphatic hydrocarbons or kerosene.

[0013] Preferably, the aromatic hydrocarbon is a C6-C12 aromatic hydrocarbon, including any one of benzene, toluene, xylene, ethylbenzene or trimethylbenzene, or a combination of at least two thereof.

[0014] Preferably, the ester compound is a C7-C18 ester compound, including any one of isononyl isononanoate, isooctyl isooctanoate, isopentyl isovalerate or amyl acetate, or a combination of at least two thereof.

[0015] Preferably, the volume ratio of the extractant to the diluent is (1-8):(2-9), for example, 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3 or 8:2, etc., but is not limited to the values ​​listed above. Other values ​​not listed within the above numerical range are also applicable.

[0016] On the other hand, the present invention also provides a method for extracting lithium from lithium-containing brine, the extraction method comprising the following steps:

[0017] (1) mixing the lithium-containing brine with the extraction system as described above to obtain a mixture, followed by extraction to obtain a loaded organic phase;

[0018] (2) mixing the loaded organic phase with a washing liquid and washing to obtain a washed organic phase;

[0019] (3) The washed organic phase is stripped to obtain a LiCl-enriched strip solution, which is then processed to obtain the Li product.

[0020] The lithium-containing brine is neutral or acidic.

[0021] The above-mentioned specific extraction method can effectively extract lithium ions from lithium-containing brine, and by adopting the above-mentioned extraction system, the calcium ions and magnesium ions in the product can be effectively reduced, and the product selectivity is high.

[0022] Preferably, the lithium ion concentration in the lithium-containing brine in step (1) is not less than 0.1 g / L.

[0023] Preferably, the molar ratio of iron ions to lithium ions in the mixture of step (1) is 1:(1-2).

[0024] Preferably, step (1) further comprises adjusting the pH to 0-1 before the extraction.

[0025] Preferably, during the extraction in step (1), the volume ratio of the organic phase to the aqueous phase is (1-10):1;

[0026] Preferably, the extraction in step (1) adopts a multi-stage countercurrent method, and the number of extraction stages is 3-7 stages.

[0027] Among them, the concentration of lithium ions can be 0.1 g / L, 0.12 g / L, 0.14 g / L, 0.16 g / L, 0.18 g / L or 0.2 g / L, etc., the molar ratio of iron ions to lithium ions can be 1:1, 1:1.2, 1:14, 1:1.6, 1:1.8 or 1:2, etc., the pH can be adjusted to 0, 0.2, 0.4, 0.6, 0.8 or 1, etc., the volume ratio of the organic phase to the aqueous phase can be 1:1, 3:1, 5:1, 7:1 or 10:1, etc., and the number of extraction stages can be 3, 4, 5, 6 or 7, etc., but are not limited to the values ​​listed above. Other values ​​not listed within the above numerical range are also applicable.

[0028] Preferably, the washing liquid in step (2) comprises water and / or LiCl solution.

[0029] Preferably, the LiCl solution is obtained by diverting the LiCl-enriched stripping solution in step (3), and the diverted volume accounts for 50-80% of the LiCl-enriched stripping solution.

[0030] Preferably, in the mixed washing of the loaded organic phase and the washing liquid in step (2), the volume ratio of the organic phase to the aqueous phase is (5-30):1.

[0031] Preferably, the washing in step (2) adopts a multi-stage countercurrent method, and the number of washing stages is 3-7 stages.

[0032] The split flow rate may account for 50%, 55%, 60%, 65%, 70%, 75% or 80% of the LiCl-enriched strip solution, the volume ratio of the organic phase to the aqueous phase may be 5:1, 10:1, 15:1, 20:1, 25:1 or 30:1, and the number of washing stages may be 3, 4, 5, 6 or 7, but is not limited to the values ​​listed above. Other values ​​not listed within the above numerical range are also applicable.

[0033] Preferably, the reagent used for the stripping in step (3) is water and / or an acid solution.

[0034] Preferably, the concentration of the acid solution is 0.01-0.1 mol / L.

[0035] Preferably, in the back extraction of step (3), the volume ratio of the organic phase to the aqueous phase is (10-30):1.

[0036] Preferably, the back extraction in step (3) adopts a multi-stage countercurrent method, and the number of back extraction stages is 5-10 stages.

[0037] Preferably, the treatment in step (3) includes concentrated crystallization or mixed precipitation with carbonate.

[0038] Preferably, the temperature of the concentrated crystallization is 80-110°C.

[0039] The concentration of the acid solution may be 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L or 0.1 mol / L, etc., the volume ratio of the organic phase to the aqueous phase may be 10:1, 15:1, 20:1, 25:1 or 30:1, etc., the number of stripping stages may be 5, 6, 7, 8, 9 or 10, etc., and the temperature for concentration and crystallization may be 80° C., 85° C., 90° C., 95° C., 100° C., 105° C. or 110° C., etc., but are not limited to the values ​​listed above. Other values ​​not listed within the above numerical range are equally applicable.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The present invention provides an extraction system for extracting lithium from lithium-containing brine. By adopting a trialkyl neutral phosphate containing a benzene ring as an extractant, the extraction effect on calcium ions and magnesium ions can be effectively affected, and the extraction of lithium ions has almost no effect, thereby effectively improving the selectivity of the extraction. The system has the advantages of high selectivity, low water solubility, strong stability, and good extraction effect, can reduce pollution to the environment, reduce costs, and has good industrial application prospects. At the same time, by selecting a specific extractant combination and compounding the three, the synergistic effect can further improve the selectivity of the extraction result compared with other extractants. DETAILED DESCRIPTION

[0042] In order to further illustrate the technical means and effects adopted by the present invention, the technical solutions of the present invention are further described below in conjunction with the preferred embodiments of the present invention, but the present invention is not limited to the scope of the embodiments.

[0043] Example 1

[0044] This embodiment provides a method for extracting lithium from lithium-containing brine, and the specific steps are as follows:

[0045] (1) triphenyl phosphate, tricresyl phosphate, diphenyl isooctyl phosphate (volume ratio 1:1:1) and kerosene (the total volume ratio of triphenyl phosphate, tricresyl phosphate, diphenyl isooctyl phosphate to kerosene is 1:1) are mixed to form an extraction system, and a co-extractant FeCl3 (the molar ratio of iron ion to lithium ion is 1:1.5) is added to the lithium-containing brine, and the above extraction system is mixed with the brine, and the volume ratio of the organic phase to the aqueous phase is 5:1, and the pH is adjusted to 0, and extraction is performed, using a multi-stage countercurrent method, and the number of extraction stages is 5 to obtain a loaded organic phase;

[0046] (2) washing the loaded organic phase obtained after extraction with a LiCl solution, with a volume ratio of the organic phase to the aqueous phase of 20:1, using a multi-stage countercurrent method with 7 washing stages; the LiCl solution is obtained by diverting 60% of the stripping solution from step (3);

[0047] (3) The washed organic phase is back-extracted with water, with a volume ratio of organic phase to aqueous phase of 20:1, to obtain a LiCl-enriched back-extract solution, and the back-extraction adopts a multi-stage countercurrent method with 10 back-extraction stages;

[0048] (4) The LiCl enriched stripping solution was concentrated and crystallized at 100° C. to obtain the LiCl product. The extraction rate was calculated to be 90% based on the amount of the LiCl product.

[0049] Example 2

[0050] This embodiment provides a method for extracting lithium from lithium-containing brine, and the specific steps are as follows:

[0051] (1) triphenyl phosphate, tricresyl phosphate, diphenyl isooctyl phosphate (volume ratio 1:1:1) and kerosene (the total volume ratio of triphenyl phosphate, tricresyl phosphate, diphenyl isooctyl phosphate to kerosene is 1:9) are mixed to form an extraction system, and a co-extractant FeCl3 (the molar ratio of iron ion to lithium ion is 1:1) is added to the lithium-containing brine, and the above extraction system is mixed with the brine, and the volume ratio of the organic phase to the aqueous phase is 1:1, and the pH is adjusted to 1, and extraction is performed, using a multi-stage countercurrent method, and the number of extraction stages is 3 to obtain a loaded organic phase;

[0052] (2) washing the loaded organic phase obtained after extraction with a LiCl solution, with a volume ratio of the organic phase to the aqueous phase of 5:1, using a multi-stage countercurrent method with 5 washing stages; the LiCl solution is obtained by diverting 60% of the stripping solution from step (3);

[0053] (3) The washed organic phase was stripped with hydrochloric acid (0.05 mol / L) at a volume ratio of 10:1 to obtain a LiCl-enriched strip solution. The stripping was carried out in a multi-stage countercurrent manner with 10 stripping stages.

[0054] (4) The LiCl enriched stripping solution was concentrated and crystallized at 100° C. to obtain the LiCl product. The extraction rate was calculated to be 84% based on the amount of the LiCl product.

[0055] Example 3

[0056] This embodiment provides a method for extracting lithium from lithium-containing brine, and the specific steps are as follows:

[0057] (1) triphenyl phosphate, tricresyl phosphate, diphenyl isooctyl phosphate (volume ratio 1:1:1) and kerosene (the volume ratio of triphenyl phosphate, tricresyl phosphate, diphenyl isooctyl phosphate to kerosene is 8:2) are mixed to form an extraction system, and a co-extractant FeCl3 (the molar ratio of iron ion to lithium ion is 1:2) is added to lithium-containing brine, and the above extraction system is mixed with the brine, and the volume ratio of the organic phase to the aqueous phase is 10:1, and the pH is adjusted to 1, and extraction is carried out, using a multi-stage countercurrent method, and the number of extraction stages is 7 to obtain a loaded organic phase;

[0058] (2) washing the loaded organic phase obtained after extraction with a LiCl solution, with a volume ratio of the organic phase to the aqueous phase of 30:1, using a multi-stage countercurrent method with 5 washing stages; the LiCl solution was obtained by diverting 60% of the stripping solution from step (3);

[0059] (3) The washed organic phase was stripped with hydrochloric acid (0.1 mol / L) at a volume ratio of 30:1 to obtain a LiCl-enriched strip solution. The stripping was carried out in a multi-stage countercurrent manner with 10 stripping stages.

[0060] (4) The LiCl-enriched stripping solution and the sodium carbonate solution were mixed and filtered to obtain lithium carbonate solid. The extraction rate was calculated to be 86% based on the amount of lithium carbonate solid.

[0061] Example 4

[0062] This embodiment provides a method for extracting lithium from lithium-containing brine. The specific steps are the same as those in Example 1, except that triphenyl phosphate is not added and the reduced amount is proportionally distributed to tricresyl phosphate and diphenyl isooctyl phosphate.

[0063] The extraction rate calculated based on the amount was 84%.

[0064] Example 5

[0065] This embodiment provides a method for extracting lithium from lithium-containing brine. The specific steps are the same as those in Example 1, except that tricresyl phosphate is not added and the reduced amount is proportionally distributed to triphenyl phosphate and diphenyl isooctyl phosphate.

[0066] The extraction rate calculated based on the amount was 90%.

[0067] Example 6

[0068] This embodiment provides a method for extracting lithium from lithium-containing brine. The specific steps are the same as those in Example 1, except that diphenyl isooctyl phosphate is not added and the reduced amount is proportionally distributed to tricresyl phosphate and triphenyl phosphate.

[0069] The extraction rate calculated based on the amount was 86%.

[0070] Example 7

[0071] This embodiment provides a method for extracting lithium from lithium-containing brine. The specific steps are the same as those in Example 1, except that tricresyl phosphate and diphenyl isooctyl phosphate are not added, and the portion allocated to triphenyl phosphate is reduced.

[0072] The extraction rate calculated based on the amount was 83%.

[0073] Example 8

[0074] This embodiment provides a method for extracting lithium from lithium-containing brine. The specific steps are the same as those in Example 1, except that triphenyl phosphate and diphenyl isooctyl phosphate are not added and the portion allocated to tricresyl phosphate is reduced.

[0075] The extraction rate calculated based on the amount was 85%.

[0076] Example 9

[0077] This embodiment provides a method for extracting lithium from lithium-containing brine. The specific steps are the same as those in Example 1, except that tricresyl phosphate and triphenyl phosphate are not added and the portion allocated to diphenyl isooctyl phosphate is reduced.

[0078] The extraction rate calculated based on the amount was 84%.

[0079] Example 10

[0080] This embodiment provides an extraction method for extracting lithium from lithium-containing brine. The specific steps are the same as those in Example 1, except that triphenyl phosphate is replaced with an equal volume of phenyl xylene phosphate.

[0081] The extraction rate calculated based on the amount was 85%.

[0082] Example 11

[0083] This embodiment provides an extraction method for extracting lithium from lithium-containing brine. The specific steps are the same as those in Example 1, except that tricresyl phosphate is replaced by an equal volume of triisopropylphenyl phosphate.

[0084] The extraction rate calculated based on the amount was 82%.

[0085] Comparative Example 1

[0086] This comparative example provides an extraction method for extracting lithium from lithium-containing brine. The specific steps are the same as those in Example 1, except that triphenyl phosphate, tricresyl phosphate, and diphenyl isooctyl phosphate are replaced by an equal volume of tributyl phosphate.

[0087] The extraction rate calculated based on the amount was 78%.

[0088] Effect test:

[0089] The lithium ions, calcium ions, and magnesium ions in the loaded organic phase and the remaining aqueous phase obtained after extraction in step (1) of the extraction method of Examples 1-11 and Comparative Example 1 were detected, and the lithium-magnesium separation coefficient and the lithium-calcium separation coefficient were calculated. The results are as follows:

[0090]

[0091] From the above data, it can be found that the extraction system and extraction method provided by the present invention have the characteristics of good extraction effect and high selectivity. By comparing Examples 1, 4-11 and Comparative Example 1, it can be found that the present invention adopts a specific extractant combination, and compared with other extractants and the conventional extractant TBP, the present invention further improves the selectivity of the extraction by compounding triphenyl phosphate, tricresyl phosphate and diphenyl isooctyl phosphate to achieve synergistic effect.

[0092] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the extraction system for extracting lithium from lithium-containing brine and its applications. However, the present invention is not limited to the above-mentioned embodiments, which does not mean that the present invention must rely on the above-mentioned embodiments in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for various raw materials in the product of the present invention, addition of auxiliary ingredients, and selection of specific methods, etc., are all within the scope of protection and disclosure of the present invention.

[0093] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0094] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. An extraction system for extracting lithium from lithium-containing brine, characterized in that: The extraction system includes an extractant and a co-extractant. The extractant is a trialkyl neutral phosphate containing a benzene ring, including any one or a combination of at least two of triphenyl phosphate, phenyl ditolyl phosphate, tricresyl phosphate, diphenyl isooctyl phosphate, monophenyl diisooctyl phosphate, triisopropylphenyl phosphate or phenyl (di-tert-butylphenyl) phosphate, and the co-extractant includes ferric chloride.

2. The extraction system according to claim 1, characterized in that The extractant is a combination of triphenyl phosphate, tricresyl phosphate and diphenyl isooctyl phosphate.

3. The extraction system according to claim 1, characterized in that The extraction system further includes a diluent, which includes any one of aromatic hydrocarbons, ester compounds, aliphatic hydrocarbons or kerosene, or a combination of at least two of them.

4. The extraction system according to claim 3, characterized in that The aromatic hydrocarbon is a C6-C12 aromatic hydrocarbon, including any one of benzene, toluene, xylene, ethylbenzene or trimethylbenzene, or a combination of at least two thereof.

5. The extraction system according to claim 3, characterized in that The ester compound is a C7-C18 ester compound, including any one of isononyl isononanoate, isooctyl isooctanoate, isopentyl isovalerate or amyl acetate, or a combination of at least two thereof.

6. The extraction system according to claim 3, characterized in that The volume ratio of the extractant to the diluent is (1-8):(2-9).

7. A method for extracting lithium from lithium-containing brine, characterized in that: The extraction method comprises the following steps: (1) mixing lithium-containing brine with the extraction system according to any one of claims 1 to 6 to obtain a mixture, followed by extraction to obtain a loaded organic phase; (2) mixing the loaded organic phase with a washing liquid and washing to obtain a washed organic phase; (3) The washed organic phase is stripped to obtain a LiCl-enriched strip solution, which is then processed to obtain the Li product.

8. The extraction method according to claim 7, characterized in that In the lithium-containing brine of step (1), the lithium ion concentration is not less than 0.1 g / L.

9. The extraction method according to claim 7, characterized in that The molar ratio of iron ions to lithium ions in the mixture of step (1) is 1:(1-2).

10. The extraction method according to claim 7, characterized in that Step (1) also includes adjusting the pH to 0-1 before the extraction.

11. The extraction method according to claim 7, characterized in that During the extraction in step (1), the volume ratio of the organic phase to the aqueous phase is (1-10):

1.

12. The extraction method according to claim 7, characterized in that The extraction in step (1) adopts a multi-stage countercurrent method, and the number of extraction stages is 3-7.

13. The extraction method according to claim 7, characterized in that The washing liquid in step (2) includes water and / or LiCl solution.

14. The extraction method according to claim 13, characterized in that The LiCl solution is obtained by splitting the LiCl-enriched stripping solution in step (3), and the split flow rate accounts for 50-80% of the LiCl-enriched stripping solution.

15. The extraction method according to claim 7, characterized in that In the step (2), the loaded organic phase is mixed with the washing liquid for washing, and the volume ratio of the organic phase to the aqueous phase is (5-30):

1.

16. The extraction method according to claim 7, characterized in that The washing in step (2) adopts a multi-stage countercurrent method, and the number of washing stages is 3-7.

17. The extraction method according to claim 7, characterized in that The reagent used for the stripping in step (3) is water and / or acid solution.

18. The extraction method according to claim 17, characterized in that The concentration of the acid solution is 0.01-0.1 mol / L.

19. The extraction method according to claim 7, characterized in that In the back extraction of step (3), the volume ratio of the organic phase to the aqueous phase is (10-30):

1.

20. The extraction method according to claim 7, characterized in that The back extraction in step (3) adopts a multi-stage countercurrent method, and the number of back extraction stages is 5-10 stages.

21. The extraction method according to claim 7, characterized in that The treatment in step (3) includes concentrated crystallization or mixed precipitation with carbonate.

22. The extraction method according to claim 21, characterized in that The temperature of the concentrated crystallization is 80-110°C.

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