Method for efficiently extracting lithium from lithium-containing mother liquor under catalysis of carbon dioxide without alkali consumption

Abstract

The invention relates to the field of hydrometallurgy, and particularly discloses a method for efficiently extracting lithium from a lithium-containing mother solution under the catalysis of carbon dioxide without alkali consumption, which comprises the following steps: S1, introducing carbon dioxide into the lithium-containing mother solution to adjust the pH value of the lithium-containing mother solution; s2, mixing a polyfluoro-substituted diketone extraction agent, a synergistic extraction agent and a diluent to prepare an extraction agent; s3, mixing the prepared extracting agent with the lithium-containing mother liquor with the adjusted pH value, and extracting according to a certain phase ratio to obtain raffinate and loaded organic matter; carrying out washing and reverse extraction on the loaded organic matter to obtain lithium-containing reverse extraction liquid; and S4, preparing battery-grade lithium sulfate or battery-grade lithium hydroxide or battery-grade lithium carbonate. The method adopts carbon dioxide to adjust pH, does not need to consume a large amount of acid and alkali, can prepare high-purity battery-grade lithium carbonate or lithium hydroxide monohydrate and battery-grade lithium sulfate products by recycling carbon dioxide generated in the extraction process, and has the advantages of easy control, simple operation, short process flow and high lithium recovery rate of the whole extraction system. The method has breakthrough significance in the battery recovery industry.

Description

Technical Field

[0001] The invention relates to the field of hydrometallurgy, in particular to a method for efficiently extracting lithium from a lithium-containing mother liquor by catalysis of carbon dioxide without alkali consumption. Background Art

[0002] In recent years, with the development of new energy vehicles, the scale of the lithium battery market has continued to expand and the consumption of lithium resources has increased. In order to meet the growing demand for lithium, the recovery of lithium from waste lithium batteries has attracted widespread attention.

[0003] The traditional lithium carbonate recovery process obtains an alkaline solution with "low lithium and high sodium" after treating the black powder of waste batteries. After concentration, a high-concentration lithium sulfate solution (Li: 20-30 g / L) is obtained. Then, the lithium carbonate product and lithium precipitation mother liquor are obtained through sodium carbonate precipitation. The lithium precipitation mother liquor is acidified with sulfuric acid to remove carbonate ions, and then evaporated and concentrated to precipitate sodium sulfate and lithium sulfate solution with high lithium concentration. Sodium carbonate is added to the lithium sulfate solution with high lithium concentration to precipitate lithium carbonate. This recovery process has the following disadvantages: (1) The secondary recovery rate of lithium in the lithium precipitation mother liquor is low (the recovery rate is less than 92.5%), and the residual carbonate in the solution is Sodium cannot be reused, resulting in excessive consumption of alkali and acid per unit (alkali consumption is 1.4 times the theoretical stoichiometric ratio); (2) Since lithium and sodium are not efficiently separated in the lithium precipitation process, the quality of the obtained lithium carbonate cannot reach battery grade, and it needs to be washed multiple times, generating a large amount of lithium washing wastewater, which increases the wastewater treatment load and reduces the lithium recovery rate. The comprehensive recovery rate of lithium elements in traditional processes is only 85%; (3) The lithium carbonate obtained by precipitation is of low grade and needs to be further processed to obtain battery-grade products, which increases the processing steps; (4) The sodium sulfate solid obtained by evaporation and concentration carries lithium, resulting in lithium loss.

[0004] In the context of advocating low-carbon emission reduction and green life, the new energy lithium battery industry is developing rapidly, and battery-grade lithium carbonate, as a key raw material for preparing lithium products, has long become a hot topic of concern. Its application areas are gradually expanding, demand is increasing, and market competition is becoming increasingly fierce; this puts forward higher requirements on how to produce qualified battery-grade lithium carbonate products at a lower cost. In order to increase the lithium recovery rate, improve the quality of lithium products, save energy and reduce consumption, promote the utilization efficiency of my country's lithium resources, and improve the comprehensive competitiveness of my country's new energy industry, it is of great significance. Summary of the invention

[0005] The purpose of the present invention is to provide a method for efficiently extracting lithium from a lithium-containing mother liquor by catalysis of carbon dioxide without alkali consumption. The extraction method of the present invention realizes efficient separation of lithium and sodium. Carbon dioxide is used to adjust the pH before extraction, and there is no need to consume a large amount of acid and alkali. The carbon dioxide generated during the extraction process can be reused, and battery-grade lithium carbonate or lithium hydroxide monohydrate and battery-grade lithium sulfate products can be obtained. The entire extraction system is easy to control, simple to operate, short in process flow, high in lithium recovery rate, and high in product purity, which has a breakthrough significance in the battery recycling industry.

[0006] In order to solve the above technical problems, the present invention provides a method for extracting lithium from a lithium-containing mother liquor by catalysis of carbon dioxide without alkali consumption and high efficiency, the method comprising the following steps:

[0007] S1. Raw material preparation

[0008] Adding carbon dioxide into the lithium-containing mother solution to adjust the pH of the lithium-containing mother solution, wherein the lithium-containing mother solution is a lithium-containing solution of a carbonate system and has a lithium concentration of 1.5-3.5 g / L;

[0009] S2. Preparation of extraction agent

[0010] The polyfluorinated diketone extractant, the co-extractant and the diluent are mixed according to a volume ratio to prepare an extractant;

[0011] S3. Lithium extraction

[0012] The prepared extractant is mixed with the lithium-containing mother liquor after adjusting pH and extracted at a certain ratio to obtain a raffinate and a loaded organic; the loaded organic is washed and stripped to obtain a lithium-containing stripping solution, and the stripped extractant is returned to S3 for extraction;

[0013] S4. Product preparation

[0014] The lithium-containing stripping solution is subjected to an evaporation process to prepare battery-grade lithium sulfate, or a bipolar membrane process to prepare battery-grade lithium hydroxide, or sodium carbonate is added to prepare battery-grade lithium carbonate.

[0015] Preferably, the carbon dioxide in S1 is high-purity carbon dioxide gas, the lithium-containing mother liquor is mixed with the high-purity carbon dioxide gas through a pressurized reactor, the pH of the lithium-containing mother liquor is adjusted to 6.5-7.5, and the pressure in the pressurized reactor is 0.2-0.9 MPa.

[0016] Preferably, the polyfluorinated diketone extractant in S2 is any one or more of 2-thenoyltrifluoroacetone (CAS No.: 326-91-0), hexafluoroacetylacetone (CAS No.: 1522-22-1), 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione (CAS No.: 326-90-9), 2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedione (CAS No.: 17587-22-3), benzoyltrifluoroacetone (CAS No.: 326-06-7), and 4,4,4-trifluoro-1,2-naphthalene-1,3-butanedione (CAS No.: 893-33-4);

[0017] The synergistic extractant is any one or more of trialkylphosphine oxide, trioctylphosphine oxide, triphenylphosphine oxide, tributyl phosphate, and trioctyl phosphate;

[0018] The diluent is any one of sulfonated kerosene, light kerosene, aviation kerosene, dodecane, toluene and ethyl acetate;

[0019] The volume ratio is based on the concentration of the polyfluoro-substituted diketone extractant being 5%-15% (V), the concentration of the co-extractant being 5%-25% (V), and the rest being the diluent.

[0020] Preferably, the carbon dioxide generated during the extraction is collected in S3 and returned to S1 to adjust the pH of the lithium-containing mother liquor.

[0021] Preferably, in S3, the extraction phase ratio is 1-3:1, the extraction time is 5-40 min, the extraction temperature is 10-50° C., and the extraction method is single-stage oscillation or multi-stage countercurrent extraction.

[0022] Preferably, the detergent in S3 is 0.01-0.5 mol / L of inorganic acid or pure water, the washing ratio is 3-10:1, the washing time is 5-20 min, and the washing temperature is 10-50°C.

[0023] Preferably, the stripping agent selected for stripping in S3 is 0.5-2 mol / L of inorganic acid, the stripping ratio is 5-15:1, the stripping time is 5-40 min, the stripping temperature is 10-50°C, the stripping method is single-stage oscillation or multi-stage countercurrent extraction, and the lithium concentration of the lithium-containing stripping solution is 10-20 g / L.

[0024] Preferably, the evaporation process in S4 refers to evaporating and concentrating the lithium-containing stripping solution by 5-10 times, and then filtering and drying to obtain battery-grade lithium sulfate; wherein the concentration temperature is 80-105°C.

[0025] Preferably, the bipolar membrane process in S4 refers to passing the lithium-containing stripping solution through an electrolytic cell using a bipolar membrane electrolysis to obtain a saturated lithium hydroxide solution of 100g / L-130g / L, and then evaporating and concentrating the lithium hydroxide solution to a liquid-to-solid ratio of 1-2:1, cooling and crystallizing to 20°C-40°C to precipitate lithium hydroxide monohydrate solid, and then centrifuging, vacuum drying, and drying to finally obtain battery-grade lithium hydroxide monohydrate; wherein the voltage of the electrolytic cell is 3-6V, and the current density is 1-100A / dm 2 , the drying temperature is 70-75℃, and the drying time is 2-4h.

[0026] Preferably, the concentration of sodium carbonate added to S4 is 200-300 g / L, the amount added is 1.1 times (molar ratio) of the lithium content in the stripping solution, the reaction temperature is 90-95°C, the reaction time is 30-90 min, and after the reaction is completed, it is filtered, washed twice at a liquid-to-solid ratio of 5:1, and then dried at 100-250°C to obtain battery-grade lithium carbonate.

[0027] The beneficial effects of the present invention are:

[0028] 1. The method for extracting lithium from lithium-containing mother liquor by carbon dioxide catalysis without alkali consumption can realize efficient recovery of lithium in lithium-containing solution of carbonate system. By introducing carbon dioxide to adjust the pH of lithium-containing mother liquor before extraction, there is no need to introduce alkaline reagent, which reduces the consumption of reagents and eliminates the large-scale use of acid and alkali. In addition, by preparing the extractant, the carbon dioxide generated in the extraction process can be reused in the pH adjustment process of lithium-containing mother liquor, thereby improving the recycling rate of carbon dioxide and reducing the extraction cost. In addition, the extraction system has a high lithium-sodium separation factor, and can directly obtain battery-grade lithium carbonate or lithium hydroxide monohydrate and battery-grade lithium sulfate products. The whole extraction system is easy to control, simple to operate, short in process flow, and the lithium recovery rate can reach 99%. The product purity is high, which has a breakthrough significance in the battery recycling industry.

[0029] 2. The method of the present invention for efficiently extracting lithium from a lithium-containing mother liquor by catalysis of carbon dioxide without alkali consumption, wherein the pH of the lithium-containing mother liquor is adjusted to 6.5-7.5 by introducing high-purity carbon dioxide gas, and the lithium-containing mother liquor is mixed with the high-purity carbon dioxide gas by using a pressurized reactor, and the pressure in the pressurized reactor is controlled to be 0.2-0.9 MPa. Here, the combination of high-purity carbon dioxide gas and pressurization can quickly adjust the pH of the lithium-containing mother liquor to 6.5-7.5, thereby accelerating the pH adjustment time of the lithium-containing mother liquor, and the extraction rate of lithium within the pH range is as high as 99% or more, thereby achieving efficient extraction of lithium;

[0030] 3. The method of the present invention for efficiently extracting lithium from a lithium-containing mother liquor by catalysis of carbon dioxide and without alkali consumption, wherein the concentration of the polyfluoro-substituted diketone extractant is 5%-15% (V), the concentration of the co-extractant is 5%-25% (V), and the rest is a diluent to prepare the extractant, and the extractant prepared under this ratio is extracted under weakly alkaline conditions (pH=6.5-7.5) by introducing carbon dioxide to adjust the pH of the mother liquor, so that the extractant loss is small, the phase separation is fast, and the extractant after stripping can be returned to the extraction section for recycling, thereby maximizing the reduction of cost investment and achieving efficient extraction of lithium, so that the lithium extraction rate is as high as more than 99%. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 The present invention is a flow chart of a method for efficiently extracting lithium from a lithium-containing mother liquor by catalysis of carbon dioxide without alkali consumption. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] like Figure 1 As shown, a method for extracting lithium from a lithium-containing mother liquor by catalysis of carbon dioxide without alkali consumption and high efficiency comprises the following steps:

[0035] S1. Raw material preparation

[0036] Carbon dioxide is introduced into the lithium-containing mother solution to adjust the pH of the lithium-containing mother solution, wherein the lithium-containing mother solution is a lithium-containing solution of a carbonate system, and the lithium concentration is 1.5-3.5 g / L; the carbon dioxide is high-purity carbon dioxide gas, and the lithium-containing mother solution and the high-purity carbon dioxide gas are mixed by a pressure reactor to adjust the pH of the lithium-containing mother solution to 6.5-7.5, and the pressure in the pressure reactor is 0.2-0.9 MPa;

[0037] S2. Preparation of extraction agent

[0038] The polyfluorinated diketone extractant, the co-extractant and the diluent are mixed according to a volume ratio to prepare an extractant;

[0039] Specifically, the polyfluorinated diketone extractant is 2-thenoyltrifluoroacetone (CAS No.: 326-91-0), hexafluoroacetylacetone (CAS No.: 1522-22-1), 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione (CAS No.: 326-90-9), 2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedione (CAS No.: 17587-22-3), benzyl Any one or more of trifluoroacetone (CAS No.: 326-06-7) and 4,4,4-trifluoro-1,2-naphthalene-1,3-butanedione (CAS No.: 893-33-4); the synergist is any one or more of trialkylphosphine oxide, trioctylphosphine oxide, triphenylphosphine oxide, tributyl phosphate and trioctyl phosphate; the diluent is any one of sulfonated kerosene, light kerosene, aviation kerosene, dodecane, toluene and ethyl acetate;

[0040] The volume ratio is based on the concentration of the polyfluorinated diketone extractant being 5%-15% (V), the concentration of the co-extractant being 5%-25% (V), and the rest being the diluent;

[0041] S3. Lithium extraction

[0042] The extractant prepared above is mixed with the lithium-containing mother liquor after adjusting the pH and extracted at a certain ratio to obtain a raffinate and a loaded organic solution, and the carbon dioxide generated during the extraction is collected and returned to S1 to adjust the pH of the lithium-containing mother liquor; wherein the extraction ratio is 1-3:1, the extraction time is 5-40min, the extraction temperature is 10-50°C, and the extraction method is single-stage oscillation or multi-stage countercurrent extraction;

[0043] The loaded organic is washed and stripped to obtain a lithium-containing stripping solution, and the stripping extractant is returned to S3 for extraction;

[0044] The detergent is 0.01-0.5 mol / L inorganic acid or pure water, the washing ratio is 3-10:1, the washing time is 5-20 min, and the washing temperature is 10-50°C;

[0045] The stripping agent selected for stripping is 0.5-2 mol / L of inorganic acid, the stripping phase ratio is 5-15:1, the stripping time is 5-40 min, the stripping temperature is 10-50° C., the stripping method is single-stage oscillation or multi-stage countercurrent extraction, and the lithium concentration of the lithium-containing stripping solution is 10-20 g / L;

[0046] S4. Product preparation

[0047] The lithium-containing stripping solution is subjected to an evaporation process to prepare battery-grade lithium sulfate, or a bipolar membrane process to prepare battery-grade lithium hydroxide, or sodium carbonate is added to prepare battery-grade lithium carbonate;

[0048] Specifically, the evaporation process refers to evaporating and concentrating the lithium-containing stripping solution by 5-10 times, and then filtering and drying to obtain battery-grade lithium sulfate; wherein the concentration temperature is 80-105°C;

[0049] Specifically, the bipolar membrane process refers to passing the lithium-containing stripping solution through an electrolytic cell using a bipolar membrane electrolysis to obtain a saturated lithium hydroxide solution of 100g / L-130g / L, and then evaporating and concentrating the lithium hydroxide solution to a liquid-to-solid ratio of 1-2:1, cooling and crystallizing to 20°C-40°C to precipitate lithium hydroxide monohydrate solid, and then centrifuging, vacuum drying, and drying to finally obtain battery-grade lithium hydroxide monohydrate; wherein the electrolytic cell voltage is 3-6V, and the current density is 1-100A / dm 2 , drying temperature is 70-75℃, and drying time is 2-4h;

[0050] Specifically, the concentration of sodium carbonate added is 200-300 g / L, the amount added is 1.1 times (molar ratio) of the lithium content in the stripping solution, the reaction temperature is 90-95°C, the reaction time is 30-90 min, and after the reaction is completed, it is filtered, washed twice according to a liquid-to-solid ratio of 5:1, and then dried at 100-250°C to obtain battery-grade lithium carbonate.

[0051] Comparative Example 1:

[0052] A method for extracting lithium from a lithium-containing mother liquor using carbon dioxide as catalyst without alkali consumption and with high efficiency, comprising the following steps:

[0053] S1. Raw material preparation

[0054] A lithium-containing mother solution (pH=10) is taken as the extraction stock solution, and the lithium concentration of the lithium-containing mother solution is 1.5 g / L;

[0055] S2. Preparation of extraction agent

[0056] 8% (V) of 2-thenoyltrifluoroacetone, 12% (V) of trialkylphosphine oxide, a co-extractant, and 80% (V) of sulfonated kerosene, a diluent, are mixed to obtain an extractant;

[0057] S3. Lithium extraction

[0058] The lithium-containing mother liquor and the extractant mixture were subjected to single-stage extraction at a ratio of 1:1, the extraction time was 5 min, the extraction temperature was 25°C, after the extraction equilibrium, the phases were allowed to stand for phase separation, and the lower aqueous phase lithium extraction residual liquid was taken for detection and analysis, the lithium content was 0.4 g / L, and the lithium extraction rate was 57%;

[0059] The loaded organic and 0.1 mol / L sulfuric acid were subjected to single-stage washing at a ratio of 10:1, the washing time was 5 min, the washing temperature was 25°C, and the phases were allowed to stand for separation; 1 mol / L sulfuric acid was selected as the stripping agent, and the washed organic was subjected to single-stage stripping at a ratio of 10:1, the stripping temperature was 25°C, the stripping time was 5 min, and the stripping was completed and the phases were allowed to stand for separation to obtain a lithium-containing stripping solution, and the lithium content was 8.9 g / L and the sodium content was 0.8 g when detected and analyzed, and the stripping rate was calculated to be 56%;

[0060] S4. Product preparation

[0061] 250 g / L sodium carbonate solution was added to the lithium-containing stripping solution, the amount of sodium carbonate added was 1.1 times (molar ratio) of the lithium content in the stripping solution, the mixture was reacted at 90° C. for 60 min and then filtered, washed twice with hot water at a liquid-to-solid ratio of 5:1, and dried at 150° C. to obtain lithium carbonate. The test results are shown in Table 2.

[0062] Embodiment 2:

[0063] A method for extracting lithium from a lithium-containing mother liquor using carbon dioxide as catalyst without alkali consumption and with high efficiency, comprising the following steps:

[0064] S1. Raw material preparation

[0065] Carbon dioxide is introduced into a lithium-containing mother solution (pH=10) with a lithium concentration of 1.5 g / L to adjust the pH to 7.5. The pressure in the reaction container is 0.3 MPa when the pH is adjusted. The solution after the pH adjustment is used as the extraction stock solution.

[0066] S2. Preparation of extraction agent

[0067] 8% (V) of 2-thenoyltrifluoroacetone, 12% (V) of trialkylphosphine oxide, a co-extractant, and 80% (V) of sulfonated kerosene, a diluent, are mixed to obtain an extractant;

[0068] S3. Lithium extraction

[0069] The lithium-containing mother liquor after pH adjustment and the extractant mixture were subjected to single-stage extraction at a ratio of 1:1, the extraction time was 5 min, the extraction temperature was 25°C, after the extraction equilibrium was reached, the phases were allowed to stand for phase separation, and the lower aqueous phase lithium extraction residual liquid was taken for detection and analysis, the lithium content was 0.015 g / L, and the lithium extraction rate was 99.4%;

[0070] The loaded organic and 0.1 mol / L sulfuric acid were subjected to single-stage washing at a ratio of 10:1, the washing time was 5 min, the washing temperature was 25°C, and the phases were allowed to stand for separation; 1 mol / L sulfuric acid was selected as the stripping agent, and the washed organic was subjected to single-stage stripping at a ratio of 10:1, the stripping temperature was 25°C, the stripping time was 5 min, and the stripping was completed and the phases were allowed to stand for separation to obtain a lithium-containing stripping solution, and the lithium content was 14.2 g / L and the sodium content was 0.014 g when detected and analyzed, and the stripping rate was calculated to be 97%;

[0071] S4. Product preparation

[0072] 250 g / L sodium carbonate solution was added to the lithium-containing stripping solution, the amount of sodium carbonate added was 1.1 times (molar ratio) of the lithium content in the stripping solution, the mixture was reacted at 90° C. for 60 min and then filtered, washed twice with hot water at a liquid-to-solid ratio of 5:1, and dried at 150° C. to obtain lithium carbonate. The test results are shown in Table 2.

[0073] Embodiment 3:

[0074] A method for extracting lithium from a lithium-containing mother liquor using carbon dioxide as catalyst without alkali consumption and with high efficiency, comprising the following steps:

[0075] S1. Raw material preparation

[0076] Carbon dioxide is introduced into a lithium-containing mother solution (pH=10) with a lithium concentration of 1.5 g / L to adjust the pH to 7.5. The pressure in the reaction container is 0.3 MPa when the pH is adjusted. The solution after the pH adjustment is used as the extraction stock solution.

[0077] S2. Preparation of extraction agent

[0078] 8% (V) of hexafluoroacetylacetone, 12% (V) of trialkylphosphine oxide as a co-extractant, and 80% (V) of sulfonated kerosene as a diluent are mixed to obtain an extractant;

[0079] S3. Lithium extraction

[0080] The lithium-containing mother liquor after pH adjustment and the extractant mixture were subjected to single-stage extraction at a ratio of 1:1, the extraction time was 5 min, the extraction temperature was 25°C, after the extraction equilibrium was reached, the phases were allowed to stand for phase separation, and the lower aqueous phase lithium extraction residual liquid was taken for detection and analysis, the lithium content was 0.02 g / L, and the lithium extraction rate was 99.35%;

[0081] The loaded organic and 0.1 mol / L sulfuric acid were subjected to single-stage washing at a ratio of 10:1, the washing time was 5 min, the washing temperature was 25°C, and the phases were allowed to stand for separation; 1 mol / L sulfuric acid was selected as the stripping agent, and the washed organic was subjected to single-stage stripping at a ratio of 10:1, the stripping temperature was 25°C, the stripping time was 5 min, and the stripping was completed and the phases were allowed to stand for separation to obtain a lithium-containing stripping solution, and the lithium content was 14.79 g / L and the sodium content was 0.011 g when detected and analyzed, and the stripping rate was calculated to be 99%;

[0082] S4. Product preparation

[0083] 250 g / L sodium carbonate solution was added to the lithium-containing stripping solution, the amount of sodium carbonate added was 1.1 times (molar ratio) of the lithium content in the stripping solution, the mixture was reacted at 90° C. for 60 min and then filtered, washed twice with hot water at a liquid-to-solid ratio of 5:1, and dried at 150° C. to obtain lithium carbonate. The test results are shown in Table 2.

[0084] Embodiment 4:

[0085] A method for extracting lithium from a lithium-containing mother liquor using carbon dioxide as catalyst without alkali consumption and with high efficiency, comprising the following steps:

[0086] S1. Raw material preparation

[0087] Carbon dioxide is introduced into a lithium-containing mother solution (pH=10) with a lithium concentration of 1.5 g / L to adjust the pH to 6.5. The pressure in the reaction container is 0.3 MPa when the pH is adjusted. The solution after the pH adjustment is used as the extraction stock solution.

[0088] S2. Preparation of extraction agent

[0089] 8% (V) of 2-thenoyltrifluoroacetone, 12% (V) of trialkylphosphine oxide, a co-extractant, and 80% (V) of sulfonated kerosene, a diluent, are mixed to obtain an extractant;

[0090] S3. Lithium extraction

[0091] The lithium-containing mother liquor after pH adjustment and the extractant mixture were subjected to single-stage extraction at a ratio of 1:1, the extraction time was 5 min, the extraction temperature was 25°C, after the extraction equilibrium was reached, the phases were allowed to stand for phase separation, and the lower aqueous phase lithium extraction residual liquid was taken for detection and analysis, the lithium content was 0.009 g / L, and the lithium extraction rate was 99.8%;

[0092] The loaded organic and 0.1 mol / L sulfuric acid were subjected to single-stage washing at a ratio of 10:1, the washing time was 5 min, the washing temperature was 25°C, and the phases were allowed to stand for separation; 1 mol / L sulfuric acid was selected as the stripping agent, and the washed organic was subjected to single-stage stripping at a ratio of 10:1, the stripping temperature was 25°C, the stripping time was 5 min, and the stripping was completed and the phases were allowed to stand for separation to obtain a lithium-containing stripping solution, and the lithium content was 15.01 g / L and the sodium content was 0.01 g when detected and analyzed, and the stripping rate was calculated to be 98.1%;

[0093] S4. Product preparation

[0094] 250 g / L sodium carbonate solution was added to the lithium-containing stripping solution, the amount of sodium carbonate added was 1.1 times (molar ratio) of the lithium content in the stripping solution, the mixture was reacted at 90° C. for 60 min and then filtered, washed twice with hot water at a liquid-to-solid ratio of 5:1, and dried at 150° C. to obtain lithium carbonate. The test results are shown in Table 2.

[0095] Embodiment 5:

[0096] A method for extracting lithium from a lithium-containing mother liquor using carbon dioxide as catalyst without alkali consumption and with high efficiency, comprising the following steps:

[0097] S1. Raw material preparation

[0098] Carbon dioxide is introduced into a lithium-containing mother solution (pH=10) with a lithium concentration of 1.5 g / L to adjust the pH to 7.5. The pressure in the reaction container is 0.3 MPa during the pH adjustment. The solution after the pH adjustment is used as the extraction stock solution.

[0099] S2. Preparation of extraction agent

[0100] 8% (V) of 2-thenoyltrifluoroacetone, 12% (V) of trialkylphosphine oxide, a co-extractant, and 80% (V) of sulfonated kerosene, a diluent, are mixed to obtain an extractant;

[0101] S3. Lithium extraction

[0102] The lithium-containing mother liquor after pH adjustment and the extractant mixture were subjected to single-stage extraction at a ratio of 1:1, the extraction time was 5 min, the extraction temperature was 25°C, after the extraction equilibrium was reached, the phases were allowed to stand for phase separation, and the lower aqueous phase lithium extraction residual liquid was taken for detection and analysis, the lithium content was 0.015 g / L, and the lithium extraction rate was 99.13%;

[0103] The loaded organic and 0.1 mol / L sulfuric acid were subjected to single-stage washing at a ratio of 10:1, the washing time was 5 min, the washing temperature was 25°C, and the phases were allowed to stand for separation; 1 mol / L sulfuric acid was selected as the stripping agent, and the washed organic was subjected to single-stage stripping at a ratio of 10:1, the stripping temperature was 25°C, the stripping time was 5 min, and the stripping was completed and the phases were allowed to stand for separation to obtain a lithium-containing stripping solution, and the lithium content was 14.2 g / L and the sodium content was 0.014 g when detected and analyzed, and the stripping rate was calculated to be 97%;

[0104] S4. Product preparation

[0105] The lithium-containing stripping solution is passed through a bipolar membrane to produce battery-grade lithium hydroxide monohydrate. The electrolytic cell voltage is 3V and the current density is 40A / dm 2 The concentration of lithium hydroxide obtained is 102g / L. After the lithium hydroxide solution is evaporated and concentrated to a liquid-solid ratio of 2:1, it is cooled and crystallized to 20°C to precipitate lithium hydroxide monohydrate solid. After centrifugal separation and vacuum drying at 70°C for 4h, battery-grade lithium hydroxide monohydrate is obtained. The test results are shown in Table 3.

[0106] Embodiment 6:

[0107] A method for extracting lithium from a lithium-containing mother liquor using carbon dioxide as catalyst without alkali consumption and with high efficiency, comprising the following steps:

[0108] S1. Raw material preparation

[0109] Carbon dioxide was introduced into a lithium-containing mother solution (pH=10) with a lithium concentration of 1.5 g / L to adjust the pH to 7.5. The pressure in the reaction container was 0.3 MPa during the pH adjustment. The solution after the pH adjustment was used as the extraction stock solution.

[0110] S2. Preparation of extraction agent

[0111] 8% (V) of 2-thenoyltrifluoroacetone, 12% (V) of trialkylphosphine oxide, a co-extractant, and 80% (V) of sulfonated kerosene, a diluent, are mixed to obtain an extractant;

[0112] S3. Lithium extraction

[0113] The lithium-containing mother liquor after pH adjustment and the extractant mixture were subjected to single-stage extraction at a ratio of 1:1, the extraction time was 5 min, the extraction temperature was 25°C, after the extraction equilibrium was reached, the phases were allowed to stand for phase separation, and the lower aqueous phase lithium extraction residual liquid was taken for detection and analysis, the lithium content was 0.015 g / L, and the lithium extraction rate was 99.62%;

[0114] The loaded organic and 0.1 mol / L sulfuric acid were subjected to single-stage washing at a ratio of 10:1, the washing time was 5 min, the washing temperature was 25°C, and the phases were allowed to stand for separation; 1 mol / L sulfuric acid was selected as the stripping agent, and the washed organic was subjected to single-stage stripping at a ratio of 10:1, the stripping temperature was 25°C, the stripping time was 5 min, and the stripping was completed and the phases were allowed to stand for separation to obtain a lithium-containing stripping solution, and the lithium content was 14.2 g / L and the sodium content was 0.014 g when detected and analyzed, and the stripping rate was calculated to be 97%;

[0115] S4. Product preparation

[0116] The lithium-containing stripping solution was evaporated and concentrated 7 times at 100°C and then filtered. The solid was dried at 110°C to obtain battery-grade lithium sulfate. The test results are shown in Table 4.

[0117] Embodiment 7:

[0118] A method for extracting lithium from a lithium-containing mother liquor using carbon dioxide as catalyst without alkali consumption and with high efficiency, comprising the following steps:

[0119] S1. Raw material preparation

[0120] Carbon dioxide is introduced into a lithium-containing mother solution (pH=10) with a lithium concentration of 3 g / L to adjust the pH to 7.5. The pressure in the reaction container is 0.3 MPa during the pH adjustment. The solution after the pH adjustment is used as the extraction stock solution.

[0121] S2. Preparation of extraction agent

[0122] 8% (V) of 2-thenoyltrifluoroacetone, 12% (V) of trialkylphosphine oxide, a co-extractant, and 80% (V) of sulfonated kerosene, a diluent, are mixed to obtain an extractant;

[0123] S3. Lithium extraction

[0124] The lithium-containing mother liquor after pH adjustment and the extractant mixture were subjected to single-stage extraction at a ratio of 2:1, the extraction time was 5 min, the extraction temperature was 25°C, after the extraction equilibrium was reached, the phases were allowed to stand for phase separation, and the lower aqueous phase lithium extraction residual liquid was taken for detection and analysis, the lithium content was 0.013 g / L, and the lithium extraction rate was 99.54%;

[0125] The loaded organic and 0.1 mol / L sulfuric acid were subjected to single-stage washing at a ratio of 10:1, the washing time was 5 min, the washing temperature was 25°C, and the phases were allowed to stand for separation; 1 mol / L sulfuric acid was selected as the stripping agent, and the washed organic was subjected to single-stage stripping at a ratio of 5:1, the stripping temperature was 25°C, the stripping time was 5 min, and the stripping was completed and the phases were allowed to stand for separation to obtain a lithium-containing stripping solution, and the lithium content was 15.7 g / L and the sodium content was 0.017 g when detected and analyzed, and the stripping rate was calculated to be 98.1%;

[0126] S4. Product preparation

[0127] 250 g / L sodium carbonate solution was added to the lithium-containing stripping solution, the amount of sodium carbonate added was 1.1 times (molar ratio) of the lithium content in the stripping solution, the mixture was reacted at 90° C. for 60 min and then filtered, washed twice with hot water at a liquid-to-solid ratio of 5:1, and dried at 150° C. to obtain lithium carbonate. The test results are shown in Table 2.

[0128] Table 1 Main parameters of the embodiment

[0129]

[0130] Table 2 Lithium carbonate composition

[0131]

[0132] Table 3 Lithium hydroxide monohydrate composition

[0133]

[0134] Table 4 Lithium sulfate composition

[0135]

[0136] In summary, the lithium extraction rate in Examples 2 to 7 of the present invention is as high as over 99%, the lithium-sodium separation factor is high under the extraction system, and battery-grade lithium carbonate or lithium hydroxide monohydrate and battery-grade lithium sulfate products can be directly obtained. The entire extraction system is easy to control, simple to operate, and has a short process flow. The lithium recovery rate can reach 99%, and the product purity is high, which is of breakthrough significance in the battery recycling industry.

[0137] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for extracting lithium from a lithium-containing mother liquor using carbon dioxide as catalyst without alkali consumption and high efficiency, characterized in that: The method comprises the following steps: S1. Raw material preparation Adding carbon dioxide into the lithium-containing mother solution to adjust the pH of the lithium-containing mother solution, wherein the lithium-containing mother solution is a lithium-containing solution of a carbonate system and has a lithium concentration of 1.5-3.5 g / L; S2. Preparation of extraction agent The polyfluorinated diketone extractant, the co-extractant and the diluent are mixed according to a volume ratio to prepare an extractant; S3. Lithium extraction The prepared extractant is mixed with the lithium-containing mother liquor after adjusting pH and extracted at a certain ratio to obtain a raffinate and a loaded organic; the loaded organic is washed and stripped to obtain a lithium-containing stripping solution, and the stripped extractant is returned to S3 for extraction; S4. Product preparation The lithium-containing stripping solution is subjected to an evaporation process to prepare battery-grade lithium sulfate, or a bipolar membrane process to prepare battery-grade lithium hydroxide, or sodium carbonate is added to prepare battery-grade lithium carbonate.

2. The method of claim 1, wherein the method comprises: The carbon dioxide in S1 is high-purity carbon dioxide gas. The lithium-containing mother liquor is mixed with the high-purity carbon dioxide gas through a pressure reactor, the pH of the lithium-containing mother liquor is adjusted to 6.5-7.5, and the pressure in the pressure reactor is 0.2-0.9 MPa.

3. The method for extracting lithium from lithium-containing mother liquor by carbon dioxide catalysis without alkali consumption according to claim 1, characterized in that: The polyfluorinated diketone extractant in S2 is any one or more of 2-thenoyltrifluoroacetone (CAS No.: 326-91-0), hexafluoroacetylacetone (CAS No.: 1522-22-1), 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione (CAS No.: 326-90-9), 2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedione (CAS No.: 17587-22-3), benzoyltrifluoroacetone (CAS No.: 326-06-7), and 4,4,4-trifluoro-1,2-naphthalene-1,3-butanedione (CAS No.: 893-33-4); The synergistic extractant is any one or more of trialkylphosphine oxide, trioctylphosphine oxide, triphenylphosphine oxide, tributyl phosphate, and trioctyl phosphate; The diluent is any one of sulfonated kerosene, light kerosene, aviation kerosene, dodecane, toluene and ethyl acetate; The volume ratio is based on the concentration of the polyfluoro-substituted diketone extractant being 5%-15% (V), the concentration of the co-extractant being 5%-25% (V), and the rest being the diluent.

4. The method of claim 1, wherein the method comprises: In S3, the carbon dioxide generated during the extraction is collected and returned to S1 to adjust the pH of the lithium-containing mother liquor.

5. The method for extracting lithium from lithium-containing mother liquor by carbon dioxide catalysis without alkali consumption and high efficiency according to claim 1, characterized in that: In the S3, the extraction phase ratio is 1-3:1, the extraction time is 5-40 min, the extraction temperature is 10-50° C., and the extraction method is single-stage oscillation or multi-stage countercurrent extraction.

6. The method of claim 1, wherein the method comprises: The detergent in S3 is 0.01-0.5 mol / L of inorganic acid or pure water, the washing ratio is 3-10:1, the washing time is 5-20 min, and the washing temperature is 10-50°C.

7. The method of claim 1 for extracting lithium from a lithium-containing mother liquor using carbon dioxide as catalyst without alkali consumption and with high efficiency, characterized in that: The stripping agent selected for stripping in S3 is 0.5-2 mol / L of inorganic acid, the stripping ratio is 5-15:1, the stripping time is 5-40 min, the stripping temperature is 10-50° C., the stripping method is single-stage oscillation or multi-stage countercurrent extraction, and the lithium concentration of the lithium-containing stripping solution is 10-20 g / L.

8. The method of claim 1 for extracting lithium from a lithium-containing mother liquor using carbon dioxide as catalyst without alkali consumption and with high efficiency, characterized in that: The evaporation process in S4 refers to evaporating and concentrating the lithium-containing stripping solution by 5-10 times, and then filtering and drying to obtain battery-grade lithium sulfate; wherein the concentration temperature is 80-105°C.

9. The method of claim 1, wherein the method comprises: The bipolar membrane process in S4 refers to using bipolar membrane electrodialysis to treat the lithium-containing stripping solution to obtain a saturated lithium hydroxide solution of 100g / L-130g / L, and then evaporating and concentrating the lithium hydroxide solution to a liquid-to-solid ratio of 1-2:1, cooling and crystallizing to 20°C-40°C to precipitate lithium hydroxide monohydrate solid, and then centrifuging, vacuum drying, and drying to finally obtain battery-grade lithium hydroxide monohydrate; wherein the electrolytic cell voltage is 3-6V, and the current density is 1-100A / dm 2 , the drying temperature is 70-75℃, and the drying time is 2-4h.

10. The method for extracting lithium from lithium-containing mother liquor by carbon dioxide catalysis without alkali consumption according to claim 1, characterized in that: The concentration of sodium carbonate added to the S4 is 200-300 g / L, the amount added is 1.1 times (molar ratio) of the lithium content in the lithium-containing stripping solution, the reaction temperature is 90-95° C., the reaction time is 30-90 min, and after the reaction is completed, it is filtered, washed twice at a liquid-to-solid ratio of 5:1, and then dried at 100-250° C. to obtain battery-grade lithium carbonate.

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