Extraction system and method for extracting lithium under alkaline condition

Abstract

The invention discloses an extraction system for extracting lithium under an alkaline condition and a method thereof. The extraction system comprises an extraction agent and a synergistic extraction agent; wherein the extraction agent comprises an alkyl group, an alkoxy group, halogen or a trifluoromethyl modified o-phenolic hydroxyl ketone compound, and the synergistic extraction agent comprises methyl alkyl substituted ammonium chloride and / or tetraalkyl ammonium bromide. Compared with an existing extraction system, the extraction system for extracting lithium under the alkaline condition has the advantages that the structure of an extraction agent is stable, side reactions are few under the alkaline condition, and the extraction performance of the extraction system is excellent; meanwhile, the method for extracting the lithium from the alkaline solution reduces the requirement on alkalinity in the extraction process, sodium ions can be removed without saponification and water washing before extraction, the extraction rate is high, the cost is reduced, and the method has industrial application potential.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium extraction, and specifically relates to an extraction system and method for lithium extraction under alkaline conditions. Background Art

[0002] Lithium is an important strategic metal element, which is widely used in fields such as lithium battery energy storage, metallurgical materials, glass manufacturing, aerospace, and controlled thermonuclear fusion reactors. With the advent of the fourth industrial revolution, especially the rapid development of the new energy industry represented by electric vehicles, the market demand for lithium resources has increased sharply, and the stable supply of lithium resources is crucial for ensuring the healthy development of the new energy industry. Therefore, it is particularly important to develop and study efficient, economical, and green lithium separation methods.

[0003] Solvent extraction for lithium extraction from alkaline lithium-containing solutions is an efficient and selective method, which is widely used in lithium extraction from salt lake brines, lithium ore leaching solutions, and industrial wastewaters. By selecting appropriate extractants, optimizing process conditions, and developing new technologies, the extraction efficiency and purity of lithium can be further improved to meet the needs of global lithium resource development.

[0004] In the patent with the application number CN201711298395.8, diketone compounds are used as extractants and neutral phosphine oxides are used as co-extractants to achieve the purpose of extracting lithium from alkaline lithium-containing brines; in the patent with the application number 202111164168.2, an extraction system with diketone compounds as extractants and halogenated phosphine compounds as co-extractants is provided, which effectively separates sodium, lithium, calcium, and magnesium from high-sodium-to-lithium ratio salt lake brines. Diketone extractants are widely used for lithium extraction in alkaline solution systems, but their chemical structures are unstable and may undergo the following side reactions under alkaline conditions: 1) Nucleophilic addition is prone to occur, generating β-hydroxy salts or further hydrolyzing to carboxyl salts; 2) Claisen condensation may occur between diketone molecules, generating insoluble polymers; 3) Under alkaline conditions, α-H is easily deprotonated to generate enolates, and further intramolecular rearrangement (such as Cope or Claisen rearrangement) may occur, resulting in structural isomerization. The above side reactions lead to an increase in polarity and water solubility during extraction, exacerbating the loss of extractants and limiting the industrial application prospects. Summary of the Invention

[0005] The main object of the present invention is to provide an extraction system and method for lithium extraction under alkaline conditions.

[0006] To achieve the aforementioned invention object, the technical solutions adopted by the present invention include:

[0007] An embodiment of the present invention provides an extraction system for lithium extraction under alkaline conditions, the extraction system comprising an extractant and a synergistic extractant; wherein, the extractant comprises an o-phenol hydroxyl ketone compound modified with an alkyl group, an alkoxy group, a halogen or a trifluoromethyl group, and the synergistic extractant comprises a methyl alkyl substituted ammonium chloride and / or a tetraalkyl ammonium bromide.

[0008] An embodiment of the present invention also provides an application of the aforementioned extraction system for lithium extraction under alkaline conditions in lithium extraction.

[0009] An embodiment of the present invention also provides a method for lithium extraction from an alkaline lithium-containing solution, which comprises:

[0010] providing the aforementioned extraction system for lithium extraction under alkaline conditions;

[0011] and, mixing the extraction system with the alkaline lithium-containing solution for extraction, water washing, and stripping treatment, so as to realize the separation and enrichment of lithium.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] (1) The present invention provides an extraction system for lithium extraction under alkaline conditions. Compared with the existing extraction systems, its advantages are that the structure of the extractant is stable, there are few side reactions under alkaline conditions, and the extraction performance of the extraction system is excellent;

[0014] (2) The present invention provides a method for lithium extraction in an alkaline solution using the above extraction system. Compared with the prior art, the advantages of the present invention are that the requirement for alkalinity is reduced during the extraction process, saponification is not required before extraction, sodium ions can be removed by water washing, the extraction rate of lithium ions is high, the process operation cost is reduced, and it has greater potential for industrial application. Detailed Embodiments

[0015] In view of the defects of the prior art, the inventors of this case have proposed the technical solution of the present invention through long-term research and a large number of practices. The present invention proposes an extraction system and method for lithium extraction from an alkaline lithium-containing solution. The lithium extraction extraction system comprises an extractant, a synergistic extractant, and a diluent. The extractant is an o-phenol hydroxyl ketone compound modified with an alkyl group, an alkoxy group, a halogen, a trifluoromethyl group, etc. The synergistic extractant is a methyl alkyl substituted ammonium chloride or a tetraalkyl ammonium bromide. The diluent is o-dichlorobenzene, chlorobenzene, toluene, dichloromethane, etc. In the alkaline environment of the extraction system of the present invention, the structure of the extractant undergoes a Keto-Enol configuration transformation, and then forms a chelate with lithium ions to achieve the selective extraction of lithium ions. Sodium ions can be removed by water washing, realizing efficient separation of lithium and sodium. The requirement for alkalinity is low during the extraction process, the extraction rate of lithium ions is high, the separation effect of lithium and sodium is good, the steps are simple, the process procedure is effectively shortened, the cost is saved, and the practical value is greatly improved.

[0016] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work belong to the scope of protection of the present invention.

[0017] Specifically, as an aspect of the technical solution of the present invention, an extraction system for lithium extraction under alkaline conditions includes an extractant and a synergistic extractant; wherein, the extractant includes an o-phenolhydroxy ketone compound modified with an alkyl group, an alkoxy group, a halogen, or a trifluoromethyl group, and the synergistic extractant includes a methylalkyl-substituted ammonium chloride and / or a tetraalkylammonium bromide.

[0018] In some preferred embodiments, the extractant has the structure shown in formula (I):

[0019]

[0020] Wherein, R is selected from any one of -C n H 2n+1 、-C n H 2n-1 、-C n H 2n-3 、-X、-OC n H 2n+1 、-CF3, amino group, substituted amino group, phenylalkyl, and X is selected from F, Cl, Br, or I;

[0021] R1 is selected from any one of -C n H 2n+1 、-OC n H 2n+1 、amino group, substituted amino group, aryl group, phenylalkyl.

[0022] Further, R is selected from -OC n H 2n+1 。

[0023] Further, R1 is selected from an aryl group.

[0024] In some preferred embodiments, the extractant has the structure shown in the following formula:

[0025]

[0026] Wherein, the substitution position of R is at the 3, 4, 5 positions of the benzene ring, preferably the 4-position substitution.

[0027] In some preferred embodiments, the methylalkyl-substituted ammonium chloride has the structure shown in the following formula:

[0028]

[0029] In some preferred embodiments, the tetraalkylammonium bromide has a structure as shown in the following formula:

[0030]

[0031] In some preferred embodiments, the synergistic extractant includes methyltrioctylammonium chloride.

[0032] In some preferred embodiments, the extraction system further includes a diluent, and the diluent includes any one or a combination of orthodichlorobenzene, chlorobenzene, toluene, dichloromethane, 1,2-dichloroethane, chloroform, ethyl acetate, and is not limited thereto.

[0033] Furthermore, the diluent is orthodichlorobenzene.

[0034] In some preferred embodiments, the molar ratio of the extractant to the synergistic extractant in the extraction system is 100:1 to 1:100.

[0035] In some preferred embodiments, the total concentration of the extractant and the synergistic extractant in the extraction system is 0.05 mol / L to 2.0 mol / L.

[0036] In the present invention, the extractant is an ortho-phenolic hydroxyl ketone skeleton substituted by R and R1, with a stable structure, strong acid and alkali tolerance, few side reactions, and little loss; the synergistic extractant is methylalkyl-substituted ammonium chloride or tetraalkylammonium bromide, which can effectively improve the extraction efficiency; the composed mixed extraction system has excellent and stable performance; when extracting under alkaline conditions, the structure of the extractant undergoes a Keto-Enol configuration transformation during the extraction process, and then coordinates with lithium ions to form a chelate, realizing the process of extracting lithium, and the lithium-sodium selective separation effect is good, and the mechanism is as shown in the following formula:

[0037]

[0038] Another aspect of the embodiments of the present invention also provides the application of the aforementioned extraction system for extracting lithium under alkaline conditions in lithium extraction, preferably in lithium extraction from alkaline solutions.

[0039] Another aspect of the embodiments of the present invention also provides a method for extracting lithium from an alkaline lithium-containing solution, which includes:

[0040] Providing the aforementioned extraction system for extracting lithium under alkaline conditions;

[0041] And, mixing the extraction system with the alkaline lithium-containing solution for extraction, water washing, and stripping treatment to realize the separation and enrichment of lithium.

[0042] In some preferred embodiments, Li in the alkaline lithium-containing solution +The concentration is 0.05 mol / L to 0.50 mol / L.

[0043] In some preferred embodiments, Na in the alkaline lithium-containing solution + The concentration is 0.05 mol / L to 2.0 mol / L.

[0044] In some preferred embodiments, OH in the alkaline lithium-containing solution - The concentration is 0.05 mol / L to 2.0 mol / L.

[0045] In some preferred embodiments, the anions in the alkaline lithium-containing solution include OH - , Cl - , CO3 2- , SO4 2- , NO3 - Any one or a combination of more than one, and is not limited thereto.

[0046] In some preferred embodiments, the method specifically includes:

[0047] Mix the extraction system with the alkaline lithium-containing solution and perform extraction at 10 to 70 °C, and separate phases to obtain a loaded organic phase and a raffinate;

[0048] And, wash the loaded organic phase with water, and then perform back-extraction on the obtained loaded organic phase with an acid to obtain a lithium-rich solution.

[0049] Further, the volume ratio of the alkaline lithium-containing solution to the extraction system is 1:10 to 10:1.

[0050] Further, the volume ratio of water to the loaded organic phase in the water washing treatment is 1:10 to 10:1.

[0051] Further, the volume ratio of the acid to the loaded organic phase in the back-extraction treatment is 25:1 to 1:25.

[0052] Further, the extraction includes single-stage shaking extraction and / or multi-stage countercurrent extraction, and is not limited thereto.

[0053] Further, the extraction time is 2 to 20 min.

[0054] Further, the acid includes any one or a combination of more than one of H2SO4, HNO3, HCl, H3PO4, H2CO3, CH3COOH, CF3COOH, CH3SO2OH, and is not limited thereto.

[0055] Further, the H+ concentration in the acid is 0.01 mol / L to 6.0 mol / L.

[0056] The present invention provides an extraction system for extracting lithium from alkaline lithium-containing solutions. The key points lie in the extractant structure, the synergist structure, the diluent composition, and the composition of the extraction system. At the same time, the present invention provides a method for extracting lithium in an alkaline solution using the above extraction system. The key points lie in direct extraction under alkaline conditions, without prior saponification, washing with water to remove sodium, and acid stripping for enrichment.

[0057] The technical solutions of the present invention will be further described in detail below in conjunction with several preferred embodiments. These embodiments are implemented on the premise of the technical solutions of the invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0058] In the following examples, the experimental materials used can be obtained from conventional biochemical reagent companies without special instructions.

[0059] Example 1

[0060] Extraction organic phase: Using 2-hydroxy-4-methoxybenzophenone as the extractant, methyltrioctylammonium chloride as the synergist, mixing in a molar ratio of 3:1, and o-dichlorobenzene as the diluent. The molar concentration of 2-hydroxy-4-methoxybenzophenone is 0.3 mol / L, and the molar concentration of methyltrioctylammonium chloride is 0.1 mol / L;

[0061] Aqueous phase to be extracted: An aqueous solution containing 0.1 mo1 / L of lithium ions, 0.2 mol / L of sodium ions, 0.2 mol / L of hydroxide ions, and 0.1 mol / L of chloride ions is used as the aqueous phase to be extracted;

[0062] Extraction: The above organic phase and the aqueous phase to be extracted are mixed in a ratio of V O / V A = 1:1. Under the condition of 25 °C, single-stage shaking extraction is carried out for 10 min. After reaching equilibrium, it is left to stand for phase separation to obtain the loaded organic phase and the raffinate. The lithium ion extraction rate is calculated through the raffinate to be 76.4%;

[0063] Washing: The above loaded organic phase and distilled water are mixed in a ratio of V O / V A = 5:1, shaken for 10 min. After reaching equilibrium, it is left to stand for phase separation to obtain the loaded organic phase, and the sodium ion elution rate is 96.7%;

[0064] Stripping: The loaded organic phase obtained in the above step is stripped with 6 mol / L hydrochloric acid in a ratio of V O / V A = 5:1 to obtain a lithium-rich solution and an empty organic phase. The stripping rate is 99.6%, and the total lithium recovery rate is 76.1%.

[0065] Example 2

[0066] Compared with Example 1, in Example 2, the molar ratio of the extractant to the synergistic extractant becomes 7:1, the molar concentration of 2-hydroxy-4-methoxybenzophenone is 0.3 mol / L, and the molar concentration of methyltrioctylammonium chloride is 0.043 mol / L, with the remaining conditions unchanged.

[0067] In the extraction step, the extraction rate of lithium ions is 52.8%, in the water washing step, the elution rate of sodium ions is 95.4%, in the stripping step, the stripping rate is 99.0%, and the total recovery rate of lithium is 52.2%.

[0068] Example 3

[0069] Compared with Example 1, in Example 3, the molar ratio of the extractant to the synergistic extractant is maintained at 3:1, o-dichlorobenzene is used as the diluent, the molar concentration of 2-hydroxy-4-methoxybenzophenone is changed to 0.36 mol / L, and the molar concentration of methyltrioctylammonium chloride is 0.12 mol / L; the remaining conditions remain unchanged.

[0070] In the extraction step, the extraction rate of lithium ions is 78.9%, in the water washing step, the elution rate of sodium ions is 96.2%, in the stripping step, the stripping rate is 99.5%, and the total recovery rate of lithium is 78.5%.

[0071] Example 4

[0072] Compared with Example 1, in Example 4, the diluent is changed to dichloromethane, and the remaining conditions remain unchanged.

[0073] In the extraction step, the extraction rate of lithium ions is 69.1%, in the water washing step, the elution rate of sodium ions is 96.0%, in the stripping step, the stripping rate is 99.7%, and the total recovery rate of lithium is 68.9%.

[0074] Example 5

[0075] Compared with Example 1, in Example 5, the aqueous phase to be extracted becomes an aqueous solution containing 0.05 mol / L of lithium ions, 0.3 mol / L of sodium ions, 0.3 mol / L of hydroxide ions, and 0.05 mol / L of chloride ions, and the remaining conditions remain unchanged.

[0076] In the extraction step, the extraction rate of lithium ions is 97.2%, in the water washing step, the elution rate of sodium ions is 95.2%, in the stripping step, the stripping rate is 99.5%, and the total recovery rate of lithium is 96.7%.

[0077] Example 6

[0078] Compared with Example 1, in Example 6, the aqueous phase to be extracted becomes an aqueous solution containing 0.1 mol / L of lithium ions, 0.45 mol / L of sodium ions, 0.45 mol / L of hydroxide ions, and 0.1 mol / L of chloride ions, and the remaining conditions remain unchanged.

[0079] The lithium ion extraction rate in the extraction step is 92.6%, the sodium ion elution rate in the water washing step is 95.3%, the stripping rate in the stripping step is 99.3%, and the total recovery rate of lithium is 92.0%.

[0080] Example 7

[0081] Compared with Example 1, in Example 7, the aqueous phase to be extracted becomes an aqueous solution containing 0.1 mol / L of lithium ions, 5.2 mol / L of sodium ions, 0.3 mol / L of hydroxide ions, and 5 mol / L of chloride ions, and the other conditions remain unchanged.

[0082] The lithium ion extraction rate in the extraction step is 95.6%, the sodium ion elution rate in the water washing step is 94.3%, the stripping rate in the stripping step is 99.2%, and the total recovery rate is 94.84%.

[0083] Example 8

[0084] Compared with Example 1, in Example 8, the extraction temperature becomes 50 °C, and the other conditions remain unchanged.

[0085] The lithium ion extraction rate in the extraction step is 81.8%, the sodium ion elution rate in the water washing step is 96.5%, the stripping rate in the stripping step is 99.7%, and the total recovery rate is 81.6%.

[0086] Example 9

[0087] Compared with Example 1, in Example 9, the extractant becomes 2-hydroxy-4-fluorobenzophenone, and the other conditions remain unchanged.

[0088] The lithium ion extraction rate in the extraction step is 41.3%, the sodium ion elution rate in the water washing step is 90.6%, the stripping rate in the stripping step is 99.2%, and the total recovery rate is 41.0%.

[0089] Example 10

[0090] Compared with Example 1, in Example 10, the co-extractant becomes tetrabutylammonium bromide, and the other conditions remain unchanged.

[0091] The lithium ion extraction rate in the extraction step is 56.3%, the sodium ion elution rate in the water washing step is 94.9%, the stripping rate in the stripping step is 99.1%, and the total recovery rate is 55.8%.

[0092] Example 11

[0093] Compared with Example 1, in Example 11, the extractant becomes isooctyl 4-fluoro-2-hydroxybenzoate, and 4 mol / L hydrochloric acid is used for stripping in the stripping step, and the other conditions remain unchanged.

[0094] The lithium ion extraction rate in the extraction step is 66.2%, the sodium ion elution rate in the water washing step is 95.7%, the stripping rate in the stripping step is 97.7%, and the total recovery rate is 64.2%.

[0095] Example 12

[0096] Extraction organic phase: Using 2-hydroxy-4-methoxybenzophenone as the extractant and methyltrioctylammonium chloride as the co-extractant, mixed in a molar ratio of 3:1, and using o-dichlorobenzene as the diluent. The molar concentration of 2-hydroxy-4-methoxybenzophenone is 1.2 mol / L, and the molar concentration of methyltrioctylammonium chloride is 0.4 mol / L;

[0097] Aqueous phase to be extracted: Table 1 shows the composition of a certain alkaline lithium-containing solution, adjusted to an alkalinity of 0.8 mol / L with NaOH as the aqueous phase to be extracted;

[0098] Table 1 Composition of a certain alkaline lithium-containing solution

[0099] ion <![CDATA[Li + > <![CDATA[Na + > <![CDATA[K + > <![CDATA[Ca 2+ > <![CDATA[Mg 2+ > pH <![CDATA[Concentration / mol*L -1 > 0.395 1.73 0.017 <![CDATA[6.1*10 -5 > <![CDATA[3.08*10 -5 > 11.5

[0100] Extraction: The above organic phase and the aqueous phase to be extracted are mixed in a ratio of V O / V A = 1:1, and under the condition of 25°C, two-stage countercurrent extraction is carried out. The single-stage extraction time is 10 min. After reaching equilibrium, standing and phase separation are carried out to obtain the loaded organic phase and the raffinate. The lithium ion extraction rate is calculated to be 99.75% through the raffinate;

[0101] Washing: The above loaded organic phase and distilled water are mixed in a ratio of V O / V A = 5:1, shaken for 10 min. After reaching equilibrium, standing and phase separation are carried out to obtain the loaded organic phase, and the sodium ion elution rate is 96.5%;

[0102] Stripping: The loaded organic phase obtained in the above step is stripped with 4 mol / L hydrochloric acid in a ratio of V O / V A = 5:1 to obtain a lithium-rich solution and an empty organic phase. The stripping rate is 98.5%, and the total lithium recovery rate is 98.25%.

[0103] Comparative Example 1

[0104] Compared with Example 1, the extractant is not added to the organic phase in Comparative Example 1, and the other conditions remain unchanged (since the lithium ion extraction rate is extremely low, the subsequent washing and stripping steps are meaningless).

[0105] The lithium ion extraction rate in the extraction step is only 1.2%.

[0106] Comparative Example 2

[0107] Compared with Example 1, the co-extractant in Comparative Example 2 is changed to trialkylphosphine oxide (TRPO), and the other conditions remain unchanged.

[0108] The lithium ion extraction rate in the extraction step is only 55.2%, the sodium ion elution rate in the water washing step is 70.53%, the stripping rate in the stripping step is 96.1%, and the total lithium recovery rate is 53.04%.

[0109] Comparative Example 3

[0110] Compared with Example 1, the extractant in Comparative Example 3 is changed to anthraquinone dihydroxy, and the other conditions remain unchanged.

[0111] The lithium ion extraction rate in the extraction step is only 17.6%, and the subsequent water washing and stripping steps are meaningless.

[0112] Comparative Example 4

[0113] Compared with Example 1, the extractant in Comparative Example 4 is changed to: 2-(hydroxy(phenyl)methyl)-5-methoxyphenol, and its structure is shown in the following formula, and the other conditions remain unchanged.

[0114]

[0115] The lithium ion extraction rate in the extraction step is only 8.5%, and the subsequent water washing and stripping steps are meaningless.

[0116] In addition, the inventors of this case also referred to the foregoing examples, and conducted tests with other raw materials, process operations, and process conditions described in this specification, and all obtained relatively ideal results.

[0117] It should be understood that the technical solutions of the present invention are not limited to the limitations of the above specific embodiments. Any technical deformation made according to the technical solutions of the present invention without departing from the spirit of the present invention and the scope protected by the claims falls within the protection scope of the present invention.

Claims

1. An extraction system for lithium extraction under alkaline conditions, characterized in that: The extraction system includes an extractant and a synergistic extractant; wherein, the extractant includes an o-phenolic hydroxyl ketone compound modified with an alkyl group, an alkoxy group, a halogen, or a trifluoromethyl group, and the synergistic extractant includes methylalkyl-substituted ammonium chloride and / or tetraalkylammonium bromide.

2. The extraction system according to claim 1, characterized in that: The extractant has a structure shown in formula (I): Among them, R is selected from -C n H 2n+1 、-C n H 2n-1 、-C n H 2n-3 、-X、-OC n H 2n+1 、-CF3, amino group, substituted amino group, phenylalkyl, and X is selected from F, Cl, Br or I; preferably, R is selected from -OC n H 2n+1 ; R1 is selected from -C n H 2n+1 、 -OC n H 2n+1 、 amino group, substituted amino group, aryl group, phenylalkyl group; preferably, R1 is selected from aryl groups.

3. The extraction system according to claim 2, wherein: The synergistic extractant includes methyltrioctylammonium chloride; And / or, the extraction system further includes a diluent, and the diluent includes any one or a combination of o-dichlorobenzene, chlorobenzene, toluene, dichloromethane, 1,2-dichloroethane, chloroform, ethyl acetate, preferably o-dichlorobenzene.

4. The extraction system according to claim 1, wherein: The molar ratio of the extractant to the synergistic extractant in the extraction system is 100:1 to 1:100; And / or, the total concentration of the extractant and the synergistic extractant in the extraction system is 0.05 mol / L to 2.0 mol / L.

5. The application of the extraction system for lithium extraction under alkaline conditions according to any one of claims 1-4 in lithium extraction, preferably in lithium extraction from an alkaline solution.

6. A method for extracting lithium from an alkaline lithium-containing solution, characterized in that, It includes: Providing the extraction system for lithium extraction under alkaline conditions according to any one of claims 1-4; And, mixing the extraction system with an alkaline lithium-containing solution for extraction, water washing, and stripping treatment to achieve the separation and enrichment of lithium.

7. The method according to claim 6, wherein Specifically, it includes: Mixing the extraction system with an alkaline lithium-containing solution and performing extraction at 10-70 °C to obtain a loaded organic phase and a raffinate by phase separation; And, washing the loaded organic phase with water, and then stripping the obtained loaded organic phase with an acid to obtain a lithium-rich solution.

8. The method according to claim 6, wherein: The concentration of Li + in the alkaline lithium-containing solution is 0.05 mol / L to 0.50 mol / L; and / or, the concentration of Na + in the alkaline lithium-containing solution is 0.05 mol / L to 2.0 mol / L; and / or, the concentration of OH - in the alkaline lithium-containing solution is 0.05 mol / L to 2.0 mol / L; And / or, the anions in the alkaline lithium-containing solution include OH - , Cl - , CO3 2- , SO4 2- , NO3 - Any one or a combination of more than one of these.

9. The method according to claim 7, wherein: The volume ratio of the alkaline lithium-containing solution to the extraction system is 1:10 to 10:1; And / or, the volume ratio of water to the loaded organic phase in the water washing treatment is 1:10 to 10:1; And / or, the volume ratio of the acid to the loaded organic phase in the stripping treatment is 25:1 to 1:

25.

10. The method according to claim 7, characterized in that: The extraction includes single-stage shaking extraction and / or multi-stage countercurrent extraction; And / or, the extraction time is 2-20 min; And / or, the acid includes any one or a combination of H2SO4, HNO3, HCl, H3PO4, H2CO3, CH3COOH, CF3COOH, CH3SO2OH; and / or, H in the acid + has a concentration of 0.01 mol / L to 6.0 mol / L.

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