CN115821040A - A solvent extraction system for efficiently extracting lithium - Google Patents

Abstract

The invention discloses a solvent extraction system for extracting lithium efficiently, which comprises carbonyl enol with a structure shown as a formula (IA or IB), organic phosphorus with a structure shown as a formula (IIA, IIB, IIC or IID), and an optional polar hydrophobic additive. In the formulae (IA) and (IB), R ₁ 、R ₂ 、R ₃ Same or different and is H or C ₁ ‑C ₁₅ Alkyl or aryl, or alkoxy, or amine groups; or, R ₁ And R ₃ Or R ₂ And R ₃ Are connected into a ring. In the formulae (IIA, IIB, IIC, IID), R ₁ 、R ₂ 、R ₃ Identical or different, each independently is C ₁ ‑C ₁₅ Alkyl or aryl of (a).

Description

A solvent extraction system for efficiently extracting lithium

technical field

The invention belongs to the technical field of chemical separation, and specifically relates to a solvent extraction system for efficiently extracting lithium.

Background technique

Lithium is the metal with the highest energy density, an important constituent element of lithium-ion batteries, and plays an important role in the field of new energy. With the gradual popularization of electric vehicles, the market demand for lithium salts is growing rapidly. However, lithium is associated with various alkali metals, which leads to low yield of lithium extraction and low purity of lithium salt. Especially for low-grade lithium resources, the current extraction efficiency of lithium is extremely low.

At present, the main sources of lithium salts are ores (such as spodumene and lepidolite), salt lake brine and battery recycling. Extracting lithium from these three resources all involves the separation of lithium and other alkali metals (sodium, potassium), such as: (1) the salt lake brine after magnesium removal is a mixed solution containing lithium, sodium, and potassium; (2) battery The solution after divalent and trivalent metals are extracted by the leachate is a mixed solution containing lithium and sodium; (3) the lithium-containing wastewater generated during battery recycling is a mixed solution containing lithium and sodium; (4) the lithium-precipitating mother liquor is a lithium-containing (5) The oil field brine after removing calcium and magnesium is a mixed solution containing lithium, sodium, and potassium; (6) The pharmaceutical wastewater of some synthetic drugs is a mixed solution containing lithium and sodium.

Existing lithium, sodium, potassium separation methods mainly contain: (1) continuously separate out sodium sulfate and potassium sulfate through repeated evaporation and concentrate lithium. This method is cumbersome, consumes a lot of energy, and has a low recovery rate of lithium. (2) Selectively extract lithium from the mixed solution by solvent extraction, and then purify and concentrate lithium by washing and stripping. Typical solvent extraction systems are those based on β-diketones and neutral organic phosphorus. However, β-diketone is an unstable compound, which can interconvert with various isomers; at the same time, β-diketone has low acidity (pKa≈10), and the activity of reacting with lithium is very low, resulting in low lithium extraction efficiency. , Alkali consumption is very large. In addition, β-diketone is easy to decompose in an alkaline environment, causing a series of problems such as loss of extractant and emulsification, which makes the extraction process difficult to operate stably.

Aiming at the problems in the prior art, the present invention provides a solvent extraction system based on carbonyl enol and organic phosphorus for efficiently extracting and extracting lithium from a lithium-containing solution. The solvent extraction system has high reactivity, high extraction selectivity, low alkali consumption and low energy consumption during the extraction process, and the extractant has a stable structure and can be used repeatedly without problems such as emulsification.

Contents of the invention

The purpose of the present invention is to provide a synergistic solvent extraction system based on carbonyl enol and organic phosphorus, which can efficiently extract lithium from lithium-containing solution, and separate lithium from impurities such as sodium and potassium while recovering lithium efficiently.

A solvent extraction system for efficiently extracting lithium, comprising a carbonyl enol having a structure shown in formula (IA or IB), an organophosphorus having a structure shown in formula (IIA, IIB, IIC or IID), and an optional pole Hydrophobic additives.

In formulas (IA) and (IB), R ₁ , R ₂ , and R ₃ can be the same or different, and are H or C ₁ -C ₁₅ alkyl or aryl, such as methyl, butyl, hexyl, octyl , dodecyl, phenyl, benzyl, phenylbutyl, etc.; or alkoxy, such as octyloxy; or amine, such as N,N-dibutylamino; or, R ₁ and R ₃ , Or R ₂ and R ₃ can be connected to form a ring, and other arbitrary groups can be connected to the ring.

The carbonyl enol can be, for example, (Z)-1-hydroxyl-1-phenyl-1-dodecen-3-one, (Z)-3-hydroxyl-1-phenyl-3-decene- 1-keto, (Z)-3-hydroxy-1-phenyl-2-decen-1-one, 1-(5-hydroxy-3-methyl-1-phenyl-4-pyrazolyl)- 1-benzophenone, 4-(1-hydroxyphenylmethylene)-5-methyl-2-benzyl-2,4-dihydro-3-pyrazolone, (Z)-3-hydroxy -1-phenyl-3-dodecen-1-one, octyl 2-hydroxybenzoate, N,N-dibutyl-2-hydroxybenzamide, etc.

In formulas (IIA) to (IID), R ₁ , R ₂ , and R ₃ may be the same or different, each independently being a C ₁ -C ₁₅ alkyl or aryl group, such as methyl, butyl, hexyl, octyl Base, dodecyl, phenyl, benzyl, phenylbutyl, etc.

The organophosphorus can be selected from one or a mixture of two or more of phosphine oxide (IIA), phosphinate (IIB), phosphonate (IIC) and phosphate (IID).

The molar ratio of the carbonyl enol to the organophosphorus is 10:1-1:10, preferably 1:1-1:4.

The polar hydrophobic additive refers to a certain polar hydrophobic solvent, which can be one or two or multiple mixtures of alcohols, ketones, ethers, esters, and the alcohols can be selected from octanol, decyl alcohol, Dodecanol etc.; Said ketone is such as 4-methyl-2-pentanone (MIBK), diisobutyl ketone (DIBK) etc.; Said ether is such as dipentyl ether, dihexyl ether etc.; Said Esters are, for example, heptyl acetate, butyl benzoate, and the like. The additive content is 0vol%-30vol%, based on the total volume of carbonyl enol, organic phosphorus and additives. Polar hydrophobic additives help to improve the solubility and phase separation of organics.

The present invention further relates to a method for efficiently extracting and extracting lithium from a lithium-containing solution using the solvent extraction system of the present invention, comprising the following steps:

(1) dissolving the solvent extraction system according to the present invention in a diluent to prepare an organic phase, the volume concentration of the extraction system is 3vol%-95vol%, based on the total volume of the organic phase;

(2) Measuring the concentration of lithium in the lithium-containing solution to be tested, adding an appropriate amount of alkali to it to improve the activity of the extraction system to extract lithium, and obtaining the aqueous phase to be extracted;

(3) Pass the organic phase prepared in step (1) and the aqueous phase obtained in step (2) into the extraction equipment, and carry out a countercurrent extraction reaction to obtain an organic phase loaded with lithium;

(4) countercurrent washing the lithium-loaded organic phase of step (3) with a washing solution to obtain the washed organic phase;

(5) carrying out counter-current back-extraction to the organic phase after step (4) washing, obtain the organic phase after back-extraction and high-purity lithium salt solution;

(6) The organic phase after stripping is returned to the organic phase storage tank, and recycled again for countercurrent extraction to extract lithium.

In step (1), the diluent is alkanes (such as kerosene, D70 solvent naphtha, etc.), aromatic hydrocarbons (such as toluene, S150 solvent naphtha, etc.), or mixed solvents thereof.

In step (2), the alkali is selected from sodium hydroxide, potassium hydroxide, ammonia water, sodium carbonate, potassium carbonate or any mixture thereof. The amount of alkali added in the solution is controlled so that the concentration of the alkali is 0.5-3.0 times the molar concentration of lithium, based on the molar concentration of lithium in the lithium-containing solution to be tested.

In step (3), the extraction equipment can use an extraction clarifier, an extraction tower or a centrifugal extractor, the number of extraction stages is 1-20, and the volume ratio of the organic phase to the aqueous phase is 1:50-50:1.

In step (4), the washing liquid is water, dilute hydrochloric acid or dilute sulfuric acid, the concentration of hydrochloric acid or sulfuric acid solution is 0.01-3.0mol/L; the volume ratio of the organic phase and the washing liquid is 1:50-50:1, The number of washing levels is 1-20.

In step (5), hydrochloric acid solution or sulfuric acid solution is used as stripping liquid, and its concentration is 0.1-12.0mol/L; The volume ratio of organic phase and stripping liquid is 1:50-50:1, and the number of stripping stages is 1 -20 levels.

The lithium recovery rate of the solvent extraction system of the invention for efficiently extracting and extracting lithium can reach more than 99%, and the lithium purity can reach more than 99.5%.

The solvent extraction system for efficient lithium extraction and extraction of the present invention can be advantageously used to extract and extract lithium from various lithium-containing solutions such as salt lake brine, oil field brine, battery leachate, ore leachate, lithium sinking mother liquor, and lithium-containing wastewater.

Beneficial effect

Compared with the prior art, the solvent extraction system of the present invention is a synergistic extraction system based on the mixture of carbonyl enol and organic phosphorus, its stability is significantly improved, the emulsification phenomenon is eliminated, and it can be recycled for a long time; the total organic matter in the raffinate The content (that is, COD) is low, and the treatment of the raffinate is simple. The solvent extraction system of the present invention has high reactivity, can fully utilize the alkali in the solution, and greatly reduces the alkali consumption in the process of extracting lithium, thereby reducing the production cost of lithium salt. The solvent extraction system of the present invention can be advantageously applied to the extraction of lithium in various lithium-containing solutions, and its advantages are particularly significant for extracting lithium from low-grade lithium-containing solutions and weakly alkaline lithium-containing solutions. Utilize the solvent extraction system of the present invention to extract the method for lithium from lithium-containing solution (such as: lithium, sodium, potassium (rubidium, cesium) mixed solution), can realize the purification and concentration of lithium simultaneously, shorten technological process, improve Lithium recovery. The solvent extraction system of the present invention is of great significance for making full use of low-grade lithium resources.

Description of drawings

Fig. 1 is a schematic flow chart of the solvent extraction system of the present invention for extracting, washing and back-extracting processes from a lithium-containing solution.

Detailed ways

The following examples illustrate the present invention more specifically, but the present invention is not limited by these examples, and those skilled in the art can make various modifications within the technical concept of the present invention.

Example 1

The lithium-containing solution to be treated is salt lake brine, and the magnesium is removed by nanofiltration, and the obtained solution contains lithium 0.2g/L, sodium 85g/L, potassium 8.6g/L, and trace amounts of magnesium, calcium, rubidium and cesium.

With 6vol% (Z)-1-hydroxy-1-phenyl-1-dodecen-3-one, 6vol% Cyanex 923 (a mixture of alkyl phosphine oxides, wherein the alkyl groups are hexyl and octyl) and 88vol % kerosene is dubbed the organic phase. Add NaOH to the lithium-containing solution to make the NaOH concentration 0.04mol/L to form an aqueous phase. The organic phase and the aqueous phase are carried out in the extraction and clarification tank according to the volume ratio of 1:5 to carry out 4-stage continuous countercurrent extraction to obtain the organic phase loaded with lithium, and the extraction rate of lithium is measured to be >98%. The organic phase of load lithium continues to wash the sodium and potassium of co-extraction with the hydrochloric acid of 0.3mol/L with the volume ratio of 20:1 in the extraction clarification tank, washes 2 grades, and washing liquid returns to the inlet of aqueous phase; Washed The organic phase continues to be back-extracted with 4mol/L hydrochloric acid in the extraction and clarification tank at a volume ratio of 20:1, and the back-extraction is 2 stages to obtain a high-purity lithium chloride solution with a lithium concentration of 18-20g/L, and its lithium concentration is measured. Purity >99.8%. The organic phase after stripping is returned to the extraction section for recycling. Lithium chloride solution was precipitated at 80°C with sodium carbonate at 0.8 times the stoichiometric ratio of lithium to obtain battery-grade lithium carbonate with a purity >99.8%.

Example 2

The lithium-containing solution to be treated is taken from the recovered lithium battery after dismantling, crushing, leaching and removal of divalent and trivalent metals. It contains lithium 2.7g/L, sodium 50g/L, and trace amounts of cobalt, nickel, Magnesium etc.

With 18vol% (Z)-3-hydroxy-1-phenyl-3-decen-1-one, 30vol% TRPO (a mixture of alkyl phosphine oxides, where the alkyl groups are heptyl and octyl) and 5vol% octyl Alcohol is dissolved in 47vol% kerosene to form the organic phase. Add NaOH to the lithium-containing solution to make the NaOH concentration 0.45mol/L to form an aqueous phase. The organic phase and the aqueous phase are subjected to three-stage continuous countercurrent extraction in the extraction and clarification tank according to the volume ratio of 1:1, and the extraction rate of lithium is >99%. The loaded organic phase continues to wash the co-extracted sodium and potassium with 0.2mol/L sulfuric acid in the extraction and clarification tank at a volume ratio of 10:1, washing for 2 stages, and the washing liquid returns to the inlet of the water phase; the organic phase after washing continues Back _- extract with 2mol/L sulfuric acid at a volume ratio of 10:1 in the extraction and clarification tank, and back-extract two stages to obtain a high-purity _Li2SO4 solution with a lithium concentration of 25-27g/L, and its lithium purity is >99.8% . The organic phase after stripping is returned to the extraction section for recycling. Lithium sulfate solution was precipitated at 80°C with sodium carbonate with a lithium stoichiometric ratio of 0.8 times to obtain battery-grade lithium carbonate with a purity of 99.8%.

Example 3

The solution to be treated is lithium-containing wastewater generated during battery recycling, with a lithium concentration of 0.5g/L and a sodium concentration of 48g/L.

Dissolve 15vol% (Z)-3-hydroxyl-1-phenyl-2-decen-1-one and 20vol% Cyanex 925 (alkyl phosphine oxide containing branched chain alkyl) in 65vol% kerosene to prepare The organic phase. Add NaOH to the lithium-containing solution to make the NaOH concentration 0.10mol/L to form an aqueous phase. The organic phase and the aqueous phase were subjected to three-stage continuous countercurrent extraction in the extraction and clarification tank according to the volume ratio of 1:5, and the extraction rate of lithium was measured to be >99%. The loaded organic phase continues to wash the co-extracted sodium with 1.0mol/L hydrochloric acid in the extraction and clarification tank at a volume ratio of 20:1, washing for 2 stages, and the washing liquid returns to the inlet of the water phase; the washed organic phase continues to be extracted In the clarification tank, 8.0mol/L hydrochloric acid was used for back extraction at a volume ratio of 20:1, and the back extraction was carried out in two stages to obtain a LiCl solution with a lithium concentration of 45-50 g/L. The organic phase after stripping is returned to the extraction section for recycling. Lithium chloride solution was precipitated at 80°C with sodium carbonate at 0.7 times the stoichiometric ratio of lithium to obtain battery-grade lithium carbonate with a purity >99.6%.

Example 4

The solution to be treated is the lithium sinking mother liquor after adding sodium carbonate to precipitate lithium carbonate in lithium sulfate solution, containing lithium 3.4g/L and sodium 46g/L.

With 18vol% 1-(5-hydroxy-3-methyl-1-phenyl-4-pyrazolyl)-1-benzophenone, 15vol% TOPO (trioctylphosphine oxide) and 5vol% P350 (methyl Dimethylheptyl phosphonate) was dissolved in 62vol% S150 solvent to form an organic phase. Lithium sinking mother liquor does not need to add alkali, directly as the water phase. The organic phase and the aqueous phase were carried out in the extraction and clarification tank according to the volume ratio of 1:1 to carry out three-stage continuous countercurrent extraction, and the extraction rate of lithium was measured to be >99%. The lithium-loaded organic phase continues to wash the co-extracted sodium with 0.5mol/L hydrochloric acid in the extraction and clarification tank at a volume ratio of 10:1, washing for 2 stages, and the washing liquid returns to the inlet of the water phase; the washed organic phase continues to Back-extract with 5mol/L hydrochloric acid at a volume ratio of 10:1 in the extraction and clarification tank, and perform two-stage back-extraction to obtain a LiCl solution with a lithium concentration of 32-35g/L. The organic phase after stripping is returned to the extraction section for recycling. Lithium chloride solution was precipitated at 80°C with sodium carbonate at 0.7 times the stoichiometric ratio of lithium to obtain battery-grade lithium carbonate with a purity >99.6%.

Example 5

The solution to be treated is a mixed solution containing lithium 0.12g/L, sodium 35g/L and potassium 10g/L obtained by nanofiltration to remove calcium and magnesium from oil field brine.

With 25vol% 4-(1-hydroxyphenylmethylene)-5-methyl-2-benzyl-2,4-dihydro-3-pyrazolone, 20vol% TRPO and 10vol% trioctyl phosphate The ester is dissolved in 45vol% S150 solvent to form an organic phase. Add NaOH to the lithium-containing solution to make the NaOH concentration 0.02mol/L, and form an aqueous phase. The organic phase and the aqueous phase are subjected to 4-stage continuous countercurrent extraction in the extraction and clarification tank according to the volume ratio of 1:50, and the extraction rate of lithium is >98%. The loaded organic phase continues to wash the co-extracted sodium with 0.8mol/L hydrochloric acid in the extraction and clarification tank at a volume ratio of 10:1, washing for 3 stages, and the washing liquid returns to the inlet of the water phase; the washed organic phase continues to be extracted Back extraction with 10 mol/L hydrochloric acid in the clarification tank at a volume ratio of 10:1, back extraction for 2 stages, to obtain a LiCl solution with a lithium concentration of 55-60 g/L. The organic phase after stripping is returned to the extraction section for recycling. The lithium chloride solution is evaporated and crystallized to obtain a lithium chloride product with a purity >99.6%.

Example 6

The solution to be treated is pharmaceutical wastewater, containing 8.2g/L lithium and 65g/L sodium.

Dissolve 20vol% (Z)-3-hydroxyl-1-phenyl-3-dodecen-1-one, 20vol% TRPO and 15vol% trihexyl phosphate in 20vol% kerosene and 25vol% S150 solvent. into the organic phase. Add NaOH to the lithium-containing solution to make the NaOH concentration 1.3 mol/L to form an aqueous phase. The organic phase and the aqueous phase are carried out in the extraction and clarification tank according to the volume ratio of 1.5:1 to carry out 4-stage continuous countercurrent extraction, and the extraction rate of lithium is measured to be >99%. The lithium-loaded organic phase continues to wash the co-extracted sodium with 1.0mol/L hydrochloric acid in the extraction and clarification tank at a volume ratio of 10:1, washing for 3 stages, and the washing liquid returns to the inlet of the water phase; the washed organic phase continues to Back-extract with 8mol/L hydrochloric acid at a volume ratio of 10:1 in the extraction and clarification tank, and perform three-stage back-extraction to obtain a LiCl solution with a lithium concentration of 50-55g/L. The organic phase after stripping is returned to the extraction section for recycling. The lithium chloride solution is evaporated and crystallized to obtain lithium chloride crystals with a purity >99.6%.

Example 7

The solution to be treated is underground brine, which contains lithium 0.26g/L, sodium 102g/L, and potassium 24g/L after removing calcium and magnesium through nanofiltration.

15vol% octyl 2-hydroxybenzoate, 15vol% TRPO and 5vol% tributyl phosphate are dissolved in 65vol% kerosene solvent to form an organic phase. Add NaOH to the lithium-containing solution to make the NaOH concentration 0.045mol/L, and form an aqueous phase. The organic phase and the aqueous phase were subjected to three-stage continuous countercurrent extraction in the extraction and clarification tank according to the volume ratio of 1:15, and the extraction rate of lithium was measured to be >99%. The lithium-loaded organic phase continues to wash the co-extracted sodium with 0.6 mol/L hydrochloric acid in the extraction and clarification tank at a volume ratio of 10:1, washing for 1 stage, and the washing liquid returns to the inlet of the water phase; the washed organic phase continues to Back-extract with 6mol/L hydrochloric acid in the extraction and clarification tank at a volume ratio of 10:1, and back-extract two stages to obtain a LiCl solution with a lithium concentration of 35-39g/L. The organic phase after stripping is returned to the extraction section for recycling. Lithium chloride solution was precipitated at 80°C with sodium carbonate at 0.7 times the stoichiometric ratio of lithium to obtain battery-grade lithium carbonate with a purity >99.6%.

Example 8

The lithium-containing solution to be treated is an old brine in a salt lake, and the magnesium is removed by nanofiltration, and the obtained solution contains lithium 1.2g/L, sodium 14g/L, and potassium 2.5g/L.

20vol% N,N-dibutyl-2-hydroxybenzamide, 20vol% TRPO and 10vol% methylheptyl methylphosphonate were dissolved in 50vol% kerosene solvent to form an organic phase. Add NaOH to the lithium-containing solution to make the NaOH concentration 0.2 mol/L to form an aqueous phase. The organic phase and the aqueous phase were carried out in the extraction and clarification tank according to the volume ratio of 1:4 for three stages of continuous countercurrent extraction, and the extraction rate of lithium was measured to be >99%. The lithium-loaded organic phase continues to wash the co-extracted sodium with 0.8 mol/L hydrochloric acid in the extraction and clarification tank at a volume ratio of 10:1, washing for 1 stage, and the washing liquid returns to the inlet of the water phase; the washed organic phase continues to Back-extract with 7mol/L hydrochloric acid in the extraction and clarification tank at a volume ratio of 10:1, and perform two-stage back-extraction to obtain a LiCl solution with a lithium concentration of 45-48g/L. The organic phase after stripping is returned to the extraction section for recycling. Lithium chloride solution was precipitated at 80°C with sodium carbonate at 0.7 times the stoichiometric ratio of lithium to obtain battery-grade lithium carbonate with a purity >99.6%.

Claims (10)

1. A solvent extraction system for efficiently extracting lithium, comprising a carbonyl enol with a structure shown in formula (IA or IB), an organophosphorus with a structure shown in formula (IIA, IIB, IIC or IID), and optionally polar hydrophobic additives;

In the formula (IA, IB), R ₁ , R ₂ , and R ₃ are the same or different, and are H or C ₁ -C ₁₅ alkyl or aryl, or alkoxy, or amine; or, R ₁ and R ₃ , or R ₂ and R ₃ are connected to form a ring;

In formulas (IIA, IIB, IIC, IID), R ₁ , R ₂ , and R ₃ are the same or different, and each is independently a C ₁ -C ₁₅ alkyl or aryl group. 2. The solvent extraction system of efficient extraction lithium extraction according to claim 1, wherein said organophosphorus is selected from phosphine oxide (IIA), phosphinate (IIB), phosphonate (IIC) and phosphoric acid ester (IID ), a mixture of two or more of them. 3. The solvent extraction system for efficiently extracting and extracting lithium according to claim 1, wherein the polar hydrophobic additive is one or two or multiple mixtures of alcohols, ketones, ethers, and esters. 4. The solvent extraction system for efficiently extracting and extracting lithium according to claim 1, wherein the mol ratio of the carbonyl enol to organic phosphorus is 10:1-1:10, preferably 1:1-1:4; additive The amount is 0vol%-30vol%, based on the total volume of carbonyl enol, organic phosphorus and additives. 5. A method for efficiently extracting and extracting lithium, using a solvent extraction system according to any one of the preceding claims, the method comprising the steps of: (1) dissolving the solvent extraction system according to any one of the preceding claims in a diluent to prepare an organic phase, the volume concentration of the extraction system is 3vol%-95vol%, based on the total volume of the organic phase; (2) Measuring the lithium concentration in the lithium-containing solution to be tested, adding an appropriate amount of alkali therein to obtain the aqueous phase to be extracted; (3) Pass the organic phase prepared in step (1) and the aqueous phase obtained in step (2) into the extraction equipment, and carry out a countercurrent extraction reaction to obtain an organic phase loaded with lithium; (4) countercurrent washing the lithium-loaded organic phase of step (3) with a washing solution to obtain the washed organic phase; (5) carrying out counter-current back-extraction to the organic phase after step (4) washing, obtain the organic phase after back-extraction and high-purity lithium salt solution; (6) The organic phase after stripping is returned to the organic phase storage tank, and recycled again for countercurrent extraction to extract lithium. 6. method according to claim 5, wherein in step (1), described diluent is alkane, aromatic hydrocarbon or its mixture; In step (2), described alkali is sodium hydroxide, potassium hydroxide, Ammonia, sodium carbonate, potassium carbonate or a mixture thereof, the amount of alkali added in the solution is controlled so that the concentration of the alkali is 0.5-3.0 times the molar concentration of lithium, based on the molar concentration of lithium in the lithium-containing solution to be measured. 7. The method according to claim 5, wherein in step (3), the volume ratio of the organic phase to the aqueous phase is 1:50-50:1. 8. The method according to claim 5, wherein in step (4), the washing liquid is water, dilute hydrochloric acid or dilute sulfuric acid, and the concentration of hydrochloric acid or sulfuric acid is 0.01-3.0mol/L; the organic phase and the washing liquid The volume ratio is 1:50-50:1. 9. method according to claim 5, wherein in step (5), use hydrochloric acid solution or sulfuric acid solution as back extraction liquid, hydrochloric acid or sulfuric acid concentration are 0.1-12.0mol/L; The volume ratio of organic phase and back extraction liquid 1:50-50:1. 10. The solvent extraction system for efficiently extracting and extracting lithium according to any one of claims 1-4 is used for extracting lithium from salt lake brine, oil field brine, battery leachate, ore leachate, lithium-precipitating mother liquor, and lithium-containing wastewater .

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