A method of extracting lithium

Abstract

The application provides a method for extracting lithium, comprising the following steps: a) mixing an extractant with a diluent to obtain an extraction organic phase; or mixing the extractant with the diluent, and then adding an alkaline solution to perform saponification to obtain the extraction organic phase; or mixing the extractant with the alkaline solution to perform saponification to obtain the extraction organic phase; b) taking an aqueous solution containing lithium ions to be extracted as an extraction aqueous phase; c) performing extraction on the extraction organic phase and the extraction aqueous phase to obtain a raffinate aqueous phase and a loaded organic phase respectively; d) performing washing on the loaded organic phase to obtain a washing raffinate and a lithium-loaded washing organic phase respectively; and e) performing stripping on the lithium-loaded washing organic phase by using a stripping solution to obtain a blank organic phase and a lithium-containing stripping solution respectively; wherein the extractant is selected from one or more of compounds of formula (1) and formula (2). The application uses a specific extractant, and can realize extraction without a synergist and effectively improve the extraction effect.

Description

Technical Field

[0001] This invention relates to the field of extraction, and in particular to a method for extracting lithium. Background Technology

[0002] Lithium is the lightest metal in nature, possessing high specific heat capacity, extremely high chemical reactivity, and a high redox potential. Therefore, lithium and lithium salts are considered important new energy sources and strategic resources. Furthermore, lithium also exhibits excellent nuclear properties. 6 Li is usually used as a raw material for thermonuclear fusion reactions; 7 Lithium (Li) is an essential material for thorium-based nuclear reactors currently under development in my country, generally used as a core coolant, a heat transfer medium, and a neutron moderator. With the continuous development of high technology and the expanding application fields of lithium products, lithium consumption is increasing daily. Therefore, accelerating the research and development of lithium salt extraction technology is of significant economic and practical importance for the utilization of my country's lithium resources.

[0003] Lithium exists in nature primarily as solid lithium ore and lithium-rich natural water. my country's lithium resources account for approximately 7.14% of the world's total lithium reserves, with 71% concentrated in salt lake brines. Most of my country's salt lakes have high magnesium-to-lithium ratios, making separation difficult. Existing lithium extraction technologies are costly, leading to my country's long-term reliance on imported lithium ore for lithium salt production. Therefore, fully utilizing salt lake lithium resources and reducing production costs is an urgent need for my country's new energy development.

[0004] Currently, industrialized lithium extraction technologies for high magnesium-to-lithium ratio salt lake brines in my country include adsorption, membrane separation, and solvent extraction. Among these, solvent extraction is favored by lithium extractors due to its high lithium selectivity, simple process flow, low freshwater consumption, and low operating costs. A typical solvent extraction system is the TBP+FeCl3 process, which suffers from the following problems: ① Excessive TBP (tributyl phosphate) dissolution loss; ② High back-extraction acidity (6-8 mol / L hydrochloric acid), easily causing TBP degradation and severe equipment corrosion; ③ The organic phase requires large amounts of alkali for regeneration, resulting in low lithium recovery rates. Meanwhile, the addition of FeCl3 brings the following problems to actual production: ① High equipment requirements: The density difference between the aqueous phase and the organic phase becomes smaller, and traditional mixing and clarification tanks cannot meet the process requirements. High-efficiency extraction equipment is required; ② Complex process flow: The acidity of the brine must be maintained to prevent Fe hydrolysis. At the same time, the brine in the extraction section must be acidified. Acidification leads to the precipitation of boron, which is associated with lithium, and filtration is required; ③ The extractant is difficult to regenerate. When regenerating the extractant with alkali, the flow rate must be precisely controlled, which can easily cause problems such as a decrease in extraction rate or emulsification and failure of the extractant. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a method for extracting lithium. The method provided by the present invention can extract lithium using a single extractant, avoiding various problems caused by the addition of co-extractants in the current solvent extraction method for lithium extraction. Moreover, it has a high extraction rate and low back-extraction acidity.

[0006] This invention provides a method for extracting lithium, comprising the following steps:

[0007] a) Mix the extractant and diluent to obtain the extracted organic phase;

[0008] or

[0009] After mixing the extractant and diluent, an alkaline solution is added for saponification to obtain the extracted organic phase;

[0010] or

[0011] The extractant is mixed with an alkaline solution and saponified to obtain the extracted organic phase;

[0012] b) Use the aqueous solution containing lithium ions to be extracted as the extraction aqueous phase;

[0013] c) Extract the organic phase and the aqueous phase to obtain the raffinate and the supported organic phase, respectively;

[0014] d) The supported organic phase is washed to obtain washing residue and lithium-loaded washed organic phase, respectively;

[0015] e) The lithium-loaded washing organic phase is back-extracted using a back-extraction solution to obtain a blank organic phase and a lithium-containing back-extraction solution, respectively;

[0016] There is no order restriction between steps a) and b).

[0017] in:

[0018] The extractant is selected from one or more of the compounds of formula (1) and formula (2);

[0019]

[0020] In formula (1):

[0021] R1 and R2 are each independently selected from: hydrogen, carbonyl, C1-C10 straight-chain or branched alkyl, C1-C10 alkoxy, or C6-C10 aromatic group;

[0022] R3 is selected from: hydrogen, C1-C10 straight-chain or branched alkyl groups, carbonyl groups, sulfonic acid groups, carboxylic acid groups, pyridyl groups, phosphorophosphonic acid groups, phosphorophosphonate groups, or C6-C10 aromatic groups; wherein, the C1-C10 straight-chain or branched alkyl groups are substituted or unsubstituted alkyl groups; when they are substituted alkyl groups, the substituents may be unsaturated substituents;

[0023] R4 is selected from: hydrogen, hydroxyl, carbonyl, C1-C20 straight-chain or branched alkyl, C1-C20 straight-chain or branched alkoxy, or C6-C10 aromatic group; wherein the C1-C10 straight-chain or branched alkyl is a substituted or unsubstituted alkyl; when it is a substituted alkyl, the substituent may be an unsaturated substituent.

[0024] n is an integer from 1 to 5;

[0025] In formula (2):

[0026] R1 and R2 are each independently selected from: hydrogen, carbonyl, C1-C10 straight-chain or branched alkyl, C1-C10 alkoxy, or C6-C10 aromatic group;

[0027] R3 and R4 are each independently selected from: hydrogen, C1-C10 straight-chain or branched alkyl groups, carbonyl groups, phosphorophosphonic acid groups, phosphorophosphonate groups, sulfonic acid groups, carboxylic acid groups, pyridyl groups, or C6-C10 aromatic groups; wherein the C1-C10 straight-chain or branched alkyl groups are substituted or unsubstituted alkyl groups; when they are substituted alkyl groups, the substituents may be unsaturated substituents;

[0028] n is an integer from 1 to 5.

[0029] Preferably, the compound of formula (1) is selected from the compounds shown in formulas 1-1 to 1-7:

[0030]

[0031]

[0032] Preferably, the compound of formula (2) is selected from the compounds shown in formulas 2-1 to 2-2:

[0033]

[0034] Preferably, the diluent is selected from at least one of C6-C16 alkanes, C6-C10 aromatics, dichloromethane, aviation kerosene, and sulfonated kerosene.

[0035] Preferably, the degree of saponification is 0% to 50%.

[0036] Preferably, in step c), the volume ratio of the extractable organic phase to the extractable aqueous phase is (1-30):(1-10).

[0037] Preferably, in step e):

[0038] The back-extraction solution is selected from at least one of water, hydrochloric acid solution, sulfuric acid solution, and nitric acid solution;

[0039] The volume ratio of the back-extraction solution to the lithium-loaded washing organic phase is 1:(1-80).

[0040] Preferably, in step d), the washing liquid used for washing is at least one of water, lithium solution, dilute sulfuric acid, dilute nitric acid, and dilute hydrochloric acid.

[0041] Preferably, after step e), the method further includes:

[0042] f) The blank organic phase is mixed with the regenerated liquid for regeneration, and the phases are separated to obtain the residual regenerated liquid and the regenerated organic phase, respectively.

[0043] Preferably, the regenerated solution is at least one of Na2CO3 aqueous solution, ammonia buffer solution, sodium hydroxide solution and carbonate buffer solution;

[0044] The preferred volume ratio of the regenerated liquid to the blank organic phase is (0.05-1):1.

[0045] Preferably, the extraction step in step c) is carried out in a separatory funnel, a mixing and clarifying extraction tank, or a centrifuge;

[0046] The back-extraction step in step e) is carried out in a separatory funnel, a mixing and clarifying extraction tank, or a centrifuge.

[0047] Preferably, the method for extracting lithium includes: loading the extractant onto a solid support to obtain a solid separation material; using the solid separation material in an alkaline solution containing lithium ions to separate lithium, thereby obtaining a lithium-containing solid separation material and a lithium extraction residue.

[0048] The solid carrier includes resin, porous silica spheres, or diatomaceous earth.

[0049] The lithium extraction method provided by this invention uses a specific extractant for extraction, achieving extraction without the need for a co-extractant and achieving a good extraction rate. It avoids various problems caused by the addition of co-extractants in current solvent extraction methods for lithium extraction. ① No complex equipment is required; conventional equipment can be used. ② The process flow is simple, eliminating the need for acidification and acidity maintenance. ③ The extractant is easily regenerated, and the regenerated extractant ensures the extraction rate. Furthermore, this invention's method can achieve low-acidity lithium back-extraction.

[0050] Experimental results show that the method provided by this invention achieves a total lithium extraction rate of over 90% and a total lithium back-extraction rate of over 96%, enabling efficient lithium extraction and back-extraction; the total lithium recovery rate reaches over 82%, enabling efficient lithium extraction; and the purity of the obtained lithium salt product is over 94%, resulting in high-quality lithium products. Furthermore, the back-extraction solution concentration used in this invention is ≤3 mol / L, achieving low-acidity lithium back-extraction. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0052] Figure 1 This is a schematic diagram of countercurrent extraction;

[0053] Figure 2 This is a schematic diagram of countercurrent washing;

[0054] Figure 3 This is a schematic diagram of countercurrent extraction.

[0055] Figure 4 This is a schematic diagram of countercurrent mixing and regeneration;

[0056] Figure 5 This is a schematic diagram of the overall extraction process in one embodiment of the present invention. Detailed Implementation

[0057] This invention provides a method for extracting lithium, comprising the following steps:

[0058] a) Mix the extractant and diluent to obtain the extracted organic phase;

[0059] or

[0060] After mixing the extractant and diluent, an alkaline solution is added for saponification to obtain the extracted organic phase;

[0061] or

[0062] The extractant is mixed with an alkaline solution and saponified to obtain the extracted organic phase;

[0063] b) Use the aqueous solution containing lithium ions to be extracted as the extraction aqueous phase;

[0064] c) Extract the organic phase and the aqueous phase to obtain the raffinate and the supported organic phase, respectively;

[0065] d) The supported organic phase is washed to obtain washing residue and lithium-loaded washed organic phase, respectively;

[0066] e) The lithium-loaded washing organic phase is back-extracted using a back-extraction solution to obtain a blank organic phase and a lithium-containing back-extraction solution, respectively;

[0067] There is no order restriction between steps a) and b).

[0068] in:

[0069] The extractant is selected from one or more of the compounds of formula (1) and formula (2);

[0070]

[0071] In formula (1):

[0072] R1 and R2 are each independently selected from: hydrogen, carbonyl, C1-C10 straight-chain or branched alkyl, C1-C10 alkoxy, or C6-C10 aromatic group;

[0073] R3 is selected from: hydrogen, C1-C10 straight-chain or branched alkyl groups, carbonyl groups, sulfonic acid groups, carboxylic acid groups, pyridyl groups, phosphorophosphonic acid groups, phosphorophosphonate groups, or C6-C10 aromatic groups; wherein, the C1-C10 straight-chain or branched alkyl groups are substituted or unsubstituted alkyl groups; when they are substituted alkyl groups, the substituents may be unsaturated substituents;

[0074] R4 is selected from: hydrogen, hydroxyl, carbonyl, C1-C20 straight-chain or branched alkyl, C1-C20 straight-chain or branched alkoxy, or C6-C10 aromatic group; wherein the C1-C10 straight-chain or branched alkyl is a substituted or unsubstituted alkyl; when it is a substituted alkyl, the substituent may be an unsaturated substituent.

[0075] n is an integer from 1 to 5;

[0076] In formula (2):

[0077] R1 and R2 are each independently selected from: hydrogen, carbonyl, C1-C10 straight-chain or branched alkyl, C1-C10 alkoxy, or C6-C10 aromatic group;

[0078] R3 and R4 are each independently selected from: hydrogen, C1-C10 straight-chain or branched alkyl groups, carbonyl groups, phosphorophosphonic acid groups, phosphorophosphonate groups, sulfonic acid groups, carboxylic acid groups, pyridyl groups, or C6-C10 aromatic groups; wherein the C1-C10 straight-chain or branched alkyl groups are substituted or unsubstituted alkyl groups; when they are substituted alkyl groups, the substituents may be unsaturated substituents;

[0079] n is an integer from 1 to 5.

[0080] The lithium extraction method provided by this invention uses a specific extractant for extraction, achieving extraction without the need for a co-extractant and achieving a good extraction rate. It avoids various problems caused by the addition of co-extractants in current solvent extraction methods for lithium extraction. ① No complex equipment is required; conventional equipment can be used. ② The process flow is simple, eliminating the need for acidification and acidity maintenance. ③ The extractant is easily regenerated, and the regenerated extractant ensures the extraction rate. Furthermore, this invention's method can achieve low-acidity lithium back-extraction.

[0081] [About Extractants] :

[0082] In this invention, the extractant is selected from one or more of the compounds of formula (1) and formula (2).

[0083] Regarding the compound of formula (1):

[0084]

[0085] R1 and R2 are each independently selected from: hydrogen, carbonyl, C1-C10 straight-chain or branched alkyl, C1-C10 alkoxy, or C6-C10 aromatic group;

[0086] R3 is selected from: hydrogen, C1-C10 straight-chain or branched alkyl groups, carbonyl groups, sulfonic acid groups, carboxylic acid groups, pyridyl groups, phosphorophosphonic acid groups, phosphorophosphonate groups, or C6-C10 aromatic groups; wherein, the C1-C10 straight-chain or branched alkyl groups are substituted or unsubstituted alkyl groups; when they are substituted alkyl groups, the substituents may be unsaturated substituents (i.e., the substituents may be saturated or unsaturated substituents).

[0087] R4 is selected from: hydrogen, hydroxyl, carbonyl, C1-C20 straight-chain or branched alkyl, C1-C20 straight-chain or branched alkoxy, or C6-C10 aromatic group; wherein the C1-C10 straight-chain or branched alkyl is a substituted or unsubstituted alkyl; when it is a substituted alkyl, the substituent may be an unsaturated substituent.

[0088] n is an integer from 1 to 5, specifically 1, 2, 3, 4, and 5.

[0089] In this invention, more preferably, the compound of formula (1) is selected from one or more of the compounds shown in formulas 1-1 to 1-7:

[0090]

[0091]

[0092] The present invention does not impose any special restrictions on the source of the compound of formula (1), which can be a commercially available product or prepared by conventional methods known to those skilled in the art.

[0093] in:

[0094] The extractant of Formula 1-1 can be prepared by the following method:

[0095] Isooctylamine, paraformaldehyde, and p-toluenesulfonic acid were dissolved in toluene. 2-Diethylphosphonite was slowly added dropwise to the mixture, and the reaction was carried out at 120°C for 6 hours. After the reaction was complete, the solvent was removed by vacuum concentration. The mixture was then vigorously stirred in an appropriate amount of ethanol with potassium hydroxide solution for 10 hours. Afterward, acid washing, water washing, and vacuum concentration were performed to remove the solvent, yielding the target product, a yellow liquid. Characterization: 1 H NMR (300MHz, CDCI3), 3.32(1H), 2.94(2H), 2.47(2H), 1.55(2H), 1.31(2H), 1.25(3H), 1.19(2H), 0.99(3H), 0.88(3H). 13 C NMR (300MHz, CDCI3), δ55.8(C), 54.6(1C), 39.9(1C), 32(1C), 29.3(1C), 26(1C), 23(1C), 14.1(1C), 11.6(1C).

[0096] The preparation process of the extractant in Formula 1-2 is largely the same as that in Formula 1-1. By controlling the amount of potassium hydroxide used during hydrolysis, the target product, a yellow phosphate ester, can be obtained. The resulting product is characterized as follows: 1 H NMR(300MHz, CDCI3), 4.08(1H), 3.83(1H), 3.32(1H), 2.94(2H), 2.60(1H), 2.35 (1H), 1.55(4H), 1.31(4H), 1.30(1H), 1.25(5H), 1.19(4H), 0.99(6H), 0.88(6H); 13 C NMR (300MHz, CDCI3), δ72.2(1C), 54.6(1C), 53.6(1C), 40.3(1C), 39.9(1C), 32.0 (1C), 30.4(1C), 29.3(2C), 26.0(1C), 23.3(1C), 23.0(2C), 14.1(2C), 11.6(2C).

[0097] The preparation process of the extractant in Formula 1-3 is largely the same as that in Formula 1-1, except that the reactants are adapted and replaced. The resulting product is characterized as follows: 1H NMR(300MHz, CDCI3), 3.32(1H), 2.94(2H), 2.60(1H), 2.35(1H), 1.73(1H), 1.55 (4H), 1.48(1H), 1.31(4H), 1.30(1H), 1.25(5H), 1.19(4H), 0.99(6H), 0.88(6H). 13 C NMR(300MHz, CDCI3), δ54.6(1C), 53.2(1C), 39.9(1C), 35.9(1C), 35.2(1C) , 32.0(1C), 29.9(1C), 29.3(2C), 26.0(1C), 23.0(2C), 14.1(2C), 11.6(2C).

[0098] The preparation process of the extractant in Formulas 1-4 is largely the same as that in Formulas 1-2, except that the reactants are adapted and replaced. The resulting product is characterized as follows: 1 H NMR (300MHz, CDCI3), 3.32(1H), 2.94(2H), 2.53(2H), 1.38(2H), 1.29(2H), 1.27(2H), 1.26(6H), 0.88(3H). 13 C NMR (300MHz, CDCI3), δ55.5(1C), 51.2(1C), 31.9(1C), 30.2(1C), 29.3(2C), 27.0(1C), 22.7(1C), 14.1(1C).

[0099] The preparation process of the extractant in Formulas 1-5 is largely the same as that in Formula 1-1, except that the reactants are adapted and replaced. The resulting product is characterized as follows: 1 H NMR (300MHz, CDCI3), δ7.86(1H), 7.66(1H), 7.13(1H), 6.81(1H), 4.08(1H), 3.83(1H) , 3.45(2H), 1.55(2H), 1.31(2H), 1.30(1H), 1.25(2H), 1.19(2H), 0.99(3H), 0.88(3H). 13 C NMR (300MHz, CDCI3), δ158.5(1C), 148.1(1C), 138.3(1C), 117.9(1C), 106.5(1C), 72.2(1 C), 55.4(1C), 40.3(1C), 30.4(1C), 29.3(1C), 23.3(1C), 23.0(1C), 14.1(1C), 11.6(1C).

[0100] The preparation process of the extractant in Formulas 1-6 is largely the same as that in Formula 1-1, except that the reactants are adapted and replaced. The resulting product is characterized as follows: 1 H NMR (300MHz, CDCI3), 4.07(2H), 2.53(2H), 1.70(2H), 1.43(2H), 1.38(2H), 1.30(4H), 1.29(2H), 1.27(2H), 1.26(10H), 0.88(6H). 13 C NMR (300MHz, CDCI3), δ66.9(1C), 53.3(1C), 51.2(1C), 31.9(2C), 31.3(1C), 30.2(1C), 29.7(1C), 29.3(2C), 27.0(1C), 22.7(2C), 14.1(2C).

[0101] The extractant of formulas 1-7 can be prepared by the following method: An appropriate amount of isooctylamine, paraformaldehyde (isooctylamine:paraformaldehyde = 1:2), and p-toluenesulfonic acid are stirred in acetonitrile for 1-2 hours. Then, product 1 is added to boiling acetonitrile and stirred vigorously for 6 hours. After completion, the solvent is removed by vacuum concentration. The mixture is then stirred vigorously in an appropriate amount of ethanol with potassium hydroxide solution for 10 hours. After completion, acid washing, water washing, and vacuum concentration are performed to remove the solvent, yielding the target product, a yellow phosphate ester. The obtained product is characterized as follows: 1 H NMR (300MHz, CDCI3), 4.08(2H), 3.83(2H), 3.32(1H), 2.94(4H), 1.55(4H), 1.31(4H), 1.30(2H), 1.25(4H), 1.19(4H), 0.99(6H), 0.88(6H). 13 C NMR (300MHz, CDCI3), δ72.2(2C), 54.6(2C), 40.3(2C), 30.4(2C), 29.3(2C), 23.3(2C), 23.0(2C), 14.1(2C), 11.6(2C).

[0102] Regarding the compound of formula (2):

[0103]

[0104] R1 and R2 are each independently selected from: hydrogen, carbonyl, C1-C10 straight-chain or branched alkyl, C1-C10 alkoxy, or C6-C10 aromatic group;

[0105] R3 and R4 are each independently selected from: hydrogen, C1-C10 straight-chain or branched alkyl groups, carbonyl groups, phosphorophosphonic acid groups, phosphorophosphonate groups, sulfonic acid groups, carboxylic acid groups, pyridyl groups, or C6-C10 aromatic groups; wherein the C1-C10 straight-chain or branched alkyl groups are substituted or unsubstituted alkyl groups; when they are substituted alkyl groups, the substituents may be unsaturated substituents.

[0106] n is an integer from 1 to 5, specifically 1, 2, 3, 4, and 5.

[0107] In this invention, more preferably, the compound of formula (2) is selected from compounds of formula 2-2 to formula 2-2:

[0108]

[0109] The present invention does not impose any special restrictions on the source of the compound of formula (2), which can be a commercially available product or prepared by conventional methods known to those skilled in the art.

[0110] in:

[0111] The extractant of Formula 2-1 can be prepared by the following method:

[0112] Diisooctylamine, paraformaldehyde, and p-toluenesulfonic acid were dissolved in toluene. 2-Diethylphosphonate was slowly added dropwise to the mixture, and the reaction was carried out at 120°C for 6 hours. After the reaction was complete, the solvent was removed by vacuum concentration. The mixture was then vigorously stirred in an appropriate amount of ethanol with potassium hydroxide solution for 10 hours. After this process, acid washing, water washing, and vacuum concentration were performed to remove the solvent, yielding the target product, a yellow liquid. Product characterization: 1 H NMR (300MHz, CDCI3), 2.75(2H), 2.40(2H), 2.16(2H), 1.55(4H), 1.31(4H), 1.25(6H), 0.99(6H), 0.88(6H). 13 C NMR (300MHz, CDCI3), δ64.5(2C), 62.8(2C), 37.7(2C), 32.3(2C), 29.3(2C), 26.3(2C), 23.0(2C), 14.1(2C), 11.6(2C).

[0113] The preparation process of the extractant in Formula 2-2 is largely the same as that in Formula 2-1, except that the reactants are adapted and replaced. Product characterization: 1 H NMR (300MHz, CDCI3), 2.75(2H), 2.46(4H), 1.36(4H), 1.29(4H), 1.27(4H), 1.26(12H), 0.88(6H). 13C NMR (300MHz, CDCI3), δ63.9(1C), 58.5(2C), 29.3(4C), 28.0(2C), 27.3(2C), 31.9(2C), 22.7(2C), 14.1(2C).

[0114] [Regarding step a]:

[0115] a) Mix the extractant and diluent to obtain the extracted organic phase;

[0116] or

[0117] After mixing the extractant and diluent, an alkaline solution is added for saponification to obtain the extracted organic phase;

[0118] or

[0119] The extractant is mixed with an alkaline solution and saponified to obtain the extracted organic phase.

[0120] The present invention can obtain the extractable organic phase in three ways: first, by mixing the extractant with the diluent to directly obtain the extractable organic phase; second, by mixing the extractant with the diluent first and then saponifying; and third, by directly saponifying the extractant without adding a diluent.

[0121] In this invention, the extractant is as described above and will not be repeated here.

[0122] In this invention, the diluent is preferably at least one of C6-C16 alkanes, C6-C10 aromatics, dichloromethane, aviation kerosene, and sulfonated kerosene, more preferably sulfonated kerosene.

[0123] In this invention, there are no special restrictions on the method of mixing the extractant and the diluent; they can be mixed evenly according to conventional mixing methods known to those skilled in the art. In this invention, the concentration of the extractant in the diluted extractant solution obtained by diluting the extractant with the diluent is preferably 0.02–3 mol / L, specifically 0.02 mol / L, 0.05 mol / L, 0.1 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, or 2.5 mol / L.

[0124] In this invention, the alkaline solution is an aqueous solution of an alkaline substance, preferably at least one of NaOH aqueous solution, LiOH aqueous solution, KOH aqueous solution and Na2CO3 aqueous solution.

[0125] In this invention, the amount of alkaline solution is preferably such that the degree of saponification reaches 0% to 50%, specifically 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50%. After saponification, an extractable organic phase is obtained.

[0126] In this invention, lithium extraction can also be performed using a solid-liquid extraction method. Specifically: an extractant is loaded onto a carrier to form a solid separation material, which is then used to separate lithium from an alkaline solution, thereby obtaining a lithium-containing solid separation material and a residual lithium extraction solution. The carrier is preferably a solid material such as resin, porous silica spheres, or diatomaceous earth.

[0127] [Regarding step b] :

[0128] b) Use the aqueous solution containing lithium ions to be extracted as the extraction aqueous phase.

[0129] In this invention, step b) preferably includes the following steps:

[0130] b1) Provide the lithium-ion-containing solution to be extracted;

[0131] b1) Detect whether the lithium-ion-containing solution is alkaline; if it is alkaline, use it directly as the extraction aqueous phase; if it is acidic, adjust the pH to alkaline and use it as the extraction aqueous phase.

[0132] The initial lithium-ion-containing solution to be extracted can be either acidic or alkaline. If it is acidic (e.g., the initial brine from a salt lake is acidic), it should be adjusted to alkaline before use. If it is alkaline (e.g., the solution after lithium precipitation from a salt lake is alkaline), it can be used directly.

[0133] In this invention, the initial lithium-ion-containing solution to be extracted can be salt lake brine, lithium precipitation mother liquor, or recycled waste battery solution.

[0134] In this invention, the pH value of the aqueous solution containing lithium ions can specifically be 7 to 14. In this invention, the alkaline substance used to adjust the pH is preferably at least one of sodium hydroxide, potassium hydroxide, and an ammonia buffer solution.

[0135] The present invention does not impose any special restrictions on the order of steps a) and b).

[0136] [Regarding step c]:

[0137] c) Extract the organic phase and the aqueous phase to obtain the raffinate and the supported organic phase, respectively.

[0138] In this invention, the volume ratio of the extractable organic phase to the extractable aqueous phase is preferably (1-30) : (1-10), and more preferably 2 : 1.

[0139] In this invention, the extraction can be either cocurrent extraction or countercurrent extraction. There are no particular limitations on the countercurrent extraction method; it can be performed according to conventional countercurrent extraction procedures, as follows: Figure 1 As shown, Figure 1This is a schematic diagram of countercurrent extraction. During the extraction process, the extractant in the organic phase exchanges hydrogen with lithium ions in the aqueous solution, and the lithium ions enter the organic phase, while the displaced hydrogen ions enter the aqueous phase: HA + Li + →LiA+H + .

[0140] In this invention, the number of countercurrent extraction stages is preferably 1 to 10, more preferably 3 to 8, specifically 3, 4, 5, 6, 7, or 8 stages. The preferred time for a single-stage countercurrent extraction is 2 to 60 minutes, specifically 2 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, or 60 minutes.

[0141] In this invention, the extraction step in step c) can be carried out in a separatory funnel, a mixing and clarifying extraction tank, or a centrifuge.

[0142] After countercurrent extraction to reach extraction equilibrium, the mixture was allowed to stand and separate into two phases: the raffinate aqueous phase and the supported organic phase (i.e., the lithium-containing organic phase).

[0143] [Regarding step d]:

[0144] d) The supported organic phase is washed to obtain washing residue and lithium-loaded washed organic phase.

[0145] In this invention, the washing solution used for washing is preferably at least one selected from water, lithium solution, dilute sulfuric acid, dilute nitric acid, and dilute hydrochloric acid. The lithium solution is preferably a high-purity lithium solution, specifically a lithium chloride solution, lithium nitrate solution, or lithium sulfate solution. The concentration of the dilute sulfuric acid is preferably 0.0001–3 mol / L; the concentration of the dilute nitric acid is preferably 0.0001–3 mol / L; and the concentration of the dilute hydrochloric acid is preferably 0.0001–3 mol / L.

[0146] In this invention, the volume ratio of the washing liquid to the supported organic phase is preferably (0.1-1):1.

[0147] In this invention, the washing method is preferably countercurrent washing, which can be carried out in a countercurrent washing system, and the process is as follows: Figure 2 As shown, Figure 2 This is a schematic diagram of countercurrent washing. Through washing, lithium ions and other impurities that have not undergone exchange reactions and are entrained in the organic phase are washed off from the organic phase and enter the washing residue.

[0148] In this invention, the number of countercurrent washing stages is preferably 1 to 8, specifically 1, 2, 3, 4, 5, 6, 7, or 8 stages. The preferred single-stage countercurrent extraction time is 2 to 60 minutes, specifically 2 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, or 60 minutes.

[0149] After countercurrent washing, the mixture was allowed to stand and separate into two phases: the washing residue and the lithium-loaded organic washing phase (i.e., the corresponding...). Figure 2 (The organic phase loaded at the outlet).

[0150] [Regarding step e]:

[0151] e) The lithium-loaded washing organic phase is back-extracted using a back-extraction solution to obtain a blank organic phase and a lithium-containing back-extraction solution, respectively.

[0152] In this invention, the back-extraction step in step e) is carried out in a separatory funnel, a mixing and clarifying extraction tank, or a centrifuge.

[0153] In this invention, the back-extraction solution is preferably at least one selected from water, hydrochloric acid, sulfuric acid, and nitric acid. The concentration of the acidic back-extraction solution is ≤3 mol / L, meaning that lithium back-extraction can be achieved at a relatively low acidity. The concentration of the hydrochloric acid solution is preferably 0.0001–3 mol / L. The concentration of the sulfuric acid solution is preferably 0.0001–3 mol / L. The nitric acid solution is preferably dilute nitric acid, with a specific concentration preferably 0.0001–3 mol / L.

[0154] In this invention, the volume ratio of the back-extraction solution to the washing organic phase loaded with lithium is preferably 1:(1-80), specifically 1:1, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, 1:65, 1:70, 1:75, or 1:80.

[0155] In this invention, the preferred method of back-extraction is countercurrent back-extraction, the process of which is as follows: Figure 3 As shown, Figure 3 This is a schematic diagram of countercurrent back-extraction. Through back-extraction, lithium loaded in the organic phase is back-extracted.

[0156] In this invention, the number of countercurrent extraction stages is preferably 1 to 8, specifically 1, 2, 3, 4, 5, 6, 7, or 8 stages. The preferred single-stage countercurrent extraction time is 2 to 60 minutes, specifically 2 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, or 60 minutes.

[0157] After countercurrent back-extraction to the point of equilibrium, the mixture was allowed to stand and separate into two phases: a blank organic phase and a lithium-containing back-extraction solution (i.e., the corresponding phase). Figure 3 (Residual back-extraction liquid at the lower middle outlet).

[0158] In this invention, the obtained lithium-containing back-extraction solution is a high-purity lithium solution. After post-processing the solution (such as precipitation and concentration), the corresponding high-purity lithium products (such as lithium carbonate, lithium chloride, etc.) can be obtained, and the purity of the lithium salt products reaches more than 95%.

[0159] In this invention, after completing the above steps a) to e), it is preferable to further perform step f): regeneration treatment.

[0160] [Regarding step f]:

[0161] f) The blank organic phase is mixed with the regenerated liquid for regeneration, and the phases are separated to obtain the residual regenerated liquid and the regenerated organic phase, respectively.

[0162] In this invention, the regenerated solution is preferably at least one of Na2CO3 aqueous solution, ammonia buffer solution, sodium hydroxide solution and carbonate buffer solution.

[0163] In this invention, the volume ratio of the regenerated liquid to the blank organic phase is preferably (0.05-1):1, specifically 0.05:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, or 1.0:1.

[0164] In this invention, the preferred method of mixed regeneration is countercurrent regeneration, which can be carried out in a countercurrent regeneration device, and the process is as follows: Figure 4 As shown, Figure 4This diagram illustrates countercurrent mixing and regeneration. During the back-extraction process of the extraction system, some inorganic acids are extracted into the organic phase in molecular form. When the extractant containing these inorganic acid molecules is used again to extract metal ions, this portion of inorganic acid causes a significant drop in the pH of the aqueous phase. This results in the pH value of the aqueous phase failing to meet the requirements of the extraction system for metal ion extraction, severely impacting the extraction efficiency. To achieve the recycling of the organic phase, it undergoes regeneration. Since the main reason for the decreased ability of the organic phase to extract metal ions again after back-extraction is the free acid loaded on the organic phase, the main purpose of regeneration is to remove this free acid. Therefore, the aforementioned alkaline regeneration solution can be used to regenerate the organic phase.

[0165] In this invention, the number of countercurrent regeneration stages is preferably 1 to 10, specifically 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 stages. The preferred single-stage countercurrent extraction time is 2 to 60 minutes, specifically 2 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, or 60 minutes.

[0166] After the above countercurrent regeneration, the mixture is allowed to stand and separate into two phases, yielding the regenerated residual liquid and the regenerated organic phase. In this invention, after obtaining the regenerated organic phase, it can be reused as the extraction organic phase in step c) for the next extraction cycle, thus repeating the cycle and reusing the extractant.

[0167] In this invention, the temperature conditions for the above-mentioned overall steps a) to f) are preferably -5℃ to 60℃.

[0168] The lithium extraction method provided by this invention is preferably a continuous lithium extraction process, carried out on a continuous lithium extraction device; wherein, the continuous lithium extraction device includes:

[0169] Extraction equipment;

[0170] A washing device whose feed inlet is connected to the organic phase outlet of the extraction device;

[0171] A back-extraction device whose feed inlet is connected to the organic phase outlet of the washing equipment;

[0172] A regeneration device whose feed inlet is connected to the organic phase outlet of the back-extraction device; the organic phase outlet of the regeneration device is connected to the organic phase inlet of the extraction device;

[0173] The continuous lithium extraction process specifically includes:

[0174] S1. Obtain the organic phase and aqueous phase for extraction, respectively;

[0175] S2. The extracted organic phase and the extracted aqueous phase are fed into an extraction device for extraction to obtain raffinate aqueous phase and loaded organic phase, respectively.

[0176] S3. The loaded organic phase and the washing liquid are fed into a washing device for washing to obtain washing residue and lithium-loaded washing organic phase, respectively.

[0177] S4. The lithium-loaded washed organic phase and the back-extraction solution are fed into a back-extraction device for back-extraction to obtain a blank organic phase and a lithium-containing back-extraction solution, respectively.

[0178] S5. The blank organic phase and the regenerated liquid are fed into the regeneration equipment for regeneration to obtain the regenerated residual liquid and the regenerated organic phase, respectively.

[0179] S6. The regenerated organic phase is used again as the extraction organic phase, and lithium extraction is carried out in a cycle according to the above steps to continuously obtain a lithium-containing back-extraction solution.

[0180] See Figure 5 , Figure 5 This is a schematic flowchart of the overall extraction process in one embodiment of the present invention. The continuous lithium extraction method and process used are as follows. Figure 5 As shown.

[0181] In steps S1 to S5 above, the types, acquisition methods, and amounts of the extracted organic phase, extracted aqueous phase, washing liquid, back-extraction liquid, and regeneration liquid are consistent with those described in the previous technical solution, and will not be repeated here. The equipment and implementation methods used for extraction, washing, back-extraction, and regeneration are also consistent with those described in the previous technical solution, and will not be repeated here.

[0182] The lithium extraction method provided by this invention uses a specific extractant for extraction, achieving extraction without the need for a co-extractant, and achieving a good extraction rate. It avoids various problems caused by the addition of co-extractants in the current solvent extraction method for lithium extraction. ① No complex equipment is required; conventional equipment can be used. ② The process is simple, without the need for acidification or acidity maintenance. ③ The extractant is easy to regenerate, and the regenerated extractant can ensure the extraction rate.

[0183] Experimental results show that the method provided by this invention achieves a total lithium extraction rate of over 90% and a total lithium back-extraction rate of over 96%, enabling efficient lithium extraction and back-extraction; the total lithium recovery rate reaches over 82%, enabling efficient lithium extraction; and the purity of the obtained lithium salt product is over 94%, resulting in high-quality lithium products. Furthermore, the back-extraction solution concentration used in this invention is ≤3 mol / L, achieving low-acidity lithium back-extraction.

[0184] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0185] Example 1

[0186] according to Figure 5 The process shown is as follows:

[0187] K1. Weigh 8.92g of the extractant shown in Formula 1-1 and dissolve it in 50mL of sulfonated kerosene. Then add NaOH aqueous solution for saponification to achieve a saponification degree of 8% to obtain the extractable organic phase.

[0188] K2. Using the filtrate after lithium precipitation in the salt lake as the extraction solution (i.e., the aqueous phase of extraction), the pH value was adjusted to 10.33. The concentrations of various ions in the extraction solution are shown in Table 1.

[0189] Table 1: Concentration of various ions in the extract solution

[0190] ion Li Na Mg Ca K Concentration, g / L 1.80 73.17 0.32 0.039 0.14

[0191] K3. The organic phase and aqueous phase are fed into the countercurrent extraction equipment at a volume ratio of 4:1 for a 5-stage countercurrent extraction reaction. The extraction time for each stage is controlled at 30 min. After reaching extraction equilibrium, the phases are separated by static separation to obtain the raffinate aqueous phase and the loaded organic phase, respectively.

[0192] K4. The loaded organic phase and dilute hydrochloric acid washing solution (0.01 mol / L concentration) are fed into a countercurrent washing device at a volume ratio of 10:1 for three-stage countercurrent washing. The washing time for each stage is 5 minutes. After standing and phase separation, the washing residue and the lithium-loaded washing organic phase are obtained respectively.

[0193] K5. The lithium-loaded washing organic phase and the back-extraction solution (1.50 mol / L hydrochloric acid solution) are fed into the countercurrent back-extraction equipment at a volume ratio of 20:1 for 4-stage countercurrent back-extraction. The single-stage back-extraction time is 20 min. After the back-extraction equilibrium is reached, the phases are separated by standing to obtain the blank organic phase and the lithium-containing back-extraction solution.

[0194] Experimental results show that the lithium extraction rate is 90% and the back-extraction rate is 96%.

[0195] The obtained lithium-containing back-extraction solution was subjected to sodium carbonate precipitation to obtain lithium carbonate product.

[0196] K6. The blank organic phase and the regenerated liquid (2 mol / L sodium carbonate aqueous solution) are fed into the countercurrent regeneration equipment at a volume ratio of 5:1 for two-stage countercurrent regeneration. The single-stage regeneration time is 10 min. After standing and phase separation, the regenerated residual liquid and the regenerated organic phase are obtained respectively.

[0197] K7. Use the regenerated organic phase as the extraction organic phase, and repeat the above steps to carry out the next lithium extraction cycle.

[0198] Example 2

[0199] according to Figure 5 The process shown is as follows:

[0200] K1. Weigh 13.4g of the extractant shown in Formula 1-2 and dissolve it in 50mL of sulfonated kerosene to obtain the extractable organic phase.

[0201] K2. The filtrate after lithium precipitation in the salt lake is used as the extraction solution (i.e., the extraction aqueous phase), and the metal ion concentration of the extraction solution is the same as in Example 1.

[0202] K3. The organic phase and aqueous phase are fed into the countercurrent extraction equipment at a volume ratio of 2:1 for a 6-stage countercurrent extraction reaction. The extraction time for each stage is controlled at 30 min. After reaching extraction equilibrium, the phases are separated by static separation to obtain the raffinate aqueous phase and the loaded organic phase, respectively.

[0203] K4. The loaded organic phase and the washing liquid (0.005 mol / L hydrochloric acid solution) are fed into the countercurrent washing equipment at a volume ratio of 10:1 for three-stage countercurrent washing. The washing time for each stage is 10 min. After standing and phase separation, the washing residue and the lithium-loaded washing organic phase are obtained respectively.

[0204] K5. The lithium-loaded washing organic phase and the back-extraction solution (3.0 mol / L hydrochloric acid solution) are fed into the countercurrent back-extraction equipment at a volume ratio of 10:1 for 4-stage countercurrent back-extraction. The single-stage back-extraction time is 20 min. After reaching back-extraction equilibrium, the phases are separated by standing to obtain the blank organic phase and the lithium-containing back-extraction solution.

[0205] Experimental results show that the lithium extraction rate is 90% and the back-extraction rate is 98%.

[0206] The obtained lithium-containing back-extraction solution was concentrated and crystallized to obtain lithium chloride product.

[0207] K6. The blank organic phase and the regenerated liquid (2 mol / L sodium carbonate aqueous solution) are fed into the countercurrent regeneration equipment at a volume ratio of 5:1 for two-stage countercurrent regeneration. The single-stage regeneration time is 20 min. After standing and phase separation, the regenerated residual liquid and the regenerated organic phase are obtained respectively.

[0208] K7. Use the regenerated organic phase as the extraction organic phase, and repeat the above steps to carry out the next lithium extraction cycle.

[0209] Example 3

[0210] according to Figure 5 The process shown is as follows:

[0211] K1. Weigh 26.15g of the extractant shown in Formula 1-7 and dissolve it in 50mL of sulfonated kerosene. Then add NaOH aqueous solution for saponification to achieve a saponification degree of 13% to obtain the extractable organic phase.

[0212] K2. The filtrate after lithium precipitation in a certain salt lake was used as the extraction solution (i.e., the extraction aqueous phase). The metal ion concentration of the extraction solution was the same as in Example 1, and the pH value was adjusted to 9.39.

[0213] K3. The organic phase and aqueous phase are fed into the countercurrent extraction equipment at a volume ratio of 1:1 for a 5-stage countercurrent extraction reaction. The extraction time for each stage is controlled at 30 min. After reaching extraction equilibrium, the phases are separated by static separation to obtain the raffinate aqueous phase and the loaded organic phase, respectively.

[0214] K4. The loaded organic phase and the washing liquid (0.02 mol / L hydrochloric acid solution) are fed into the countercurrent washing equipment at a volume ratio of 10:1 for two-stage countercurrent washing. The washing time for each stage is 20 min. After standing and phase separation, the washing residue and the lithium-loaded washing organic phase are obtained respectively.

[0215] K5. The lithium-loaded washing organic phase and the back-extraction solution (3.0 mol / L hydrochloric acid solution) are fed into the countercurrent back-extraction equipment at a volume ratio of 10:1 for 4-stage countercurrent back-extraction. The single-stage back-extraction time is 20 min. After reaching back-extraction equilibrium, the phases are separated by standing to obtain the blank organic phase and the lithium-containing back-extraction solution.

[0216] Experimental results show that the lithium extraction rate is 95% and the back-extraction rate is 96%.

[0217] The obtained lithium-containing back-extraction solution was subjected to sodium carbonate precipitation to obtain lithium carbonate product.

[0218] K6. The blank organic phase and the regenerated liquid (2 mol / L sodium carbonate aqueous solution) are fed into the countercurrent regeneration equipment at a volume ratio of 5:1 for three-stage countercurrent regeneration. The single-stage regeneration time is 10 min. After standing and phase separation, the regenerated residual liquid and the regenerated organic phase are obtained respectively.

[0219] K7. Use the regenerated organic phase as the extraction organic phase, and repeat the above steps to carry out the next lithium extraction cycle.

[0220] Example 4

[0221] K1. Weigh 13.4g of the extractant shown in Formula 2-1 and dissolve it in 50mL of sulfonated kerosene to obtain the extractable organic phase.

[0222] K2, the filtrate after lithium precipitation in the salt lake is used as the extraction liquid (i.e., the extraction aqueous phase), which is the same as in Example 1.

[0223] K3. The organic phase and aqueous phase are fed into the countercurrent extraction device at a volume ratio of 3:1 for a 4-stage countercurrent extraction reaction. The extraction time for each stage is controlled at 30 min. After reaching extraction equilibrium, the phases are separated by static separation to obtain the raffinate aqueous phase and the loaded organic phase, respectively.

[0224] K4. The loaded organic phase and the washing liquid (0.005 mol / L hydrochloric acid solution) are fed into the countercurrent washing equipment at a volume ratio of 10:1 for three-stage countercurrent washing. The washing time for each stage is 20 min. After standing and phase separation, the washing residue and the lithium-loaded washing organic phase are obtained respectively.

[0225] K5. The lithium-loaded washing organic phase and the back-extraction solution (1.5 mol / L hydrochloric acid solution) are fed into the countercurrent back-extraction equipment at a volume ratio of 10:1 for three-stage countercurrent back-extraction. The single-stage back-extraction time is 10 min. After reaching back-extraction equilibrium, the phases are separated by standing to obtain the blank organic phase and the lithium-containing back-extraction solution.

[0226] Experimental results show that the lithium extraction rate is 90% and the back-extraction rate is 98%.

[0227] The obtained lithium-containing back-extraction solution was subjected to sodium carbonate precipitation to obtain lithium carbonate product.

[0228] K6. The blank organic phase and the regenerated liquid (2 mol / L sodium carbonate aqueous solution) are fed into the countercurrent regeneration equipment at a volume ratio of 5:1 for two-stage countercurrent regeneration. The single-stage regeneration time is 10 min. After standing and phase separation, the regenerated residual liquid and the regenerated organic phase are obtained respectively.

[0229] K7. Use the regenerated organic phase as the extraction organic phase, and repeat the above steps to carry out the next lithium extraction cycle.

[0230] Comparative Example 1

[0231] The procedure was carried out as described in Example 3, except that extractants 1-7 were replaced with compounds of the following formula:

[0232]

[0233] The following tests were performed on the above embodiments and comparative examples: 1. pH value of the lithium solution in step K2; 2. Total extraction rate, total back-extraction rate and total recovery rate of lithium after the lithium extraction process; 3. Purity of the lithium salt product obtained from the lithium extraction process; The experimental results are shown in Table 2.

[0234] Table 2: Detection results of Examples 1-4 and Comparative Example 1

[0235]

[0236] As can be seen from the test results in Table 1, the method provided by this invention achieves a total lithium extraction rate of over 90% and a total lithium back-extraction rate of over 96%, enabling efficient lithium extraction and back-extraction; the total lithium recovery rate reaches over 82%, enabling efficient lithium extraction; and the purity of the obtained lithium salt product is over 94%, resulting in high-quality lithium products. Furthermore, the back-extraction solution concentration in Examples 1-4 is ≤3 mol / L, achieving low-acidity lithium back-extraction.

[0237] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of these embodiments are merely to aid in understanding the method and core ideas of the present invention, including the best mode, and to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to those expressed in the claims, or if they include equivalent structural elements that are not substantially different from those expressed in the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A method for extracting lithium, characterized in that, Includes the following steps: a) Mix the extractant and diluent to obtain the extracted organic phase; or After mixing the extractant and diluent, an alkaline solution is added for saponification to obtain the extracted organic phase; or The extractant is mixed with an alkaline solution and saponified to obtain the extracted organic phase; b1) Provide the lithium-ion-containing solution to be extracted; b1) Detect whether the lithium-ion-containing solution is alkaline; If it is alkaline, it can be used directly as the aqueous phase for extraction; If it is acidic, adjust the pH to alkaline and then use it as the extraction aqueous phase; c) Extract the organic phase and the aqueous phase to obtain the raffinate and the supported organic phase, respectively; d) The supported organic phase is washed to obtain washing residue and lithium-loaded washed organic phase, respectively; e) The lithium-loaded washing organic phase is back-extracted using a back-extraction solution to obtain a blank organic phase and a lithium-containing back-extraction solution, respectively; There is no order restriction between steps a) and b). in: The extractant is selected from one or more of the compounds shown in Formula 1-1, Formula 1-4, Formula 2-1, and Formula 2-2; Equation 1-1 Equation 1-4 Equation 2-1 Equation 2-2.

2. The method according to claim 1, characterized in that, The diluent is selected from at least one of C6-C16 alkanes, C6-C10 aromatics, dichloromethane, aviation kerosene, and sulfonated kerosene.

3. The method according to claim 1, characterized in that, The degree of saponification is 0% to 50%.

4. The method according to claim 1, characterized in that, In step c), the volume ratio of the extracted organic phase to the extracted aqueous phase is (1~30):(1~10).

5. The method according to claim 1, characterized in that, In step e): The back-extraction solution is selected from at least one of water, hydrochloric acid solution, sulfuric acid solution, and nitric acid solution; The volume ratio of the back-extraction solution to the lithium-loaded washing organic phase is 1:(1~80).

6. The method according to claim 1, characterized in that, In step d), the washing liquid used for washing is at least one of water, lithium solution, dilute sulfuric acid, dilute nitric acid, and dilute hydrochloric acid.

7. The method according to claim 1, characterized in that, Following step e), the method further includes: f) The blank organic phase is mixed with the regenerated liquid for regeneration, and the phases are separated to obtain the residual regenerated liquid and the regenerated organic phase, respectively.

8. The method according to claim 7, characterized in that, The regeneration solution is at least one of Na2CO3 aqueous solution, ammonia buffer solution, sodium hydroxide solution and carbonate buffer solution; The volume ratio of the regenerated liquid to the blank organic phase is (0.05~1):

1.

9. The method according to claim 1, characterized in that, The extraction step in step c) is carried out in a separatory funnel, a mixing and clarifying extraction tank, or a centrifuge. The back-extraction step in step e) is carried out in a separatory funnel, a mixing and clarifying extraction tank, or a centrifuge.

Images