Waste lithium iron phosphate battery recovery process

Abstract

The invention discloses a waste lithium iron phosphate battery recovery process. The process comprises the following steps: S1, powder roasting: roasting a positive electrode material; s2, powder leaching: selectively leaching the roasted positive electrode material through hydrogen peroxide and a sulfuric acid solution; s3, impurity metal extraction: calcium, aluminum, iron and copper impurity metals are separated through a cationic extractant; s4, anion extraction: separating anions through an anion extraction agent to obtain a crude lithium hydroxide solution, a fluorine-containing sodium sulfate solution and sodium phosphate; s5, sodium fluoride separation: separating sodium fluoride and sodium sulfate from the fluorine-containing sodium sulfate solution through evaporation concentration and freezing crystallization; s6, preparing lithium hydroxide, namely precipitating and separating magnesium hydroxide from the crude lithium hydroxide solution, evaporating, concentrating, cooling, crystallizing and separating sodium to obtain a lithium hydroxide solution; and S7, preparing a lithium hydroxide product: evaporating and crystallizing the lithium hydroxide solution to obtain the lithium hydroxide product. The method provided by the invention realizes deep recovery and resource utilization of phosphorus, fluorine and lithium in waste lithium iron phosphate.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery recycling, and in particular relates to a process for recycling waste lithium iron phosphate batteries. Background Art

[0002] With the maturing new energy vehicle market and the rapid expansion of new materials, the global lithium-ion battery recycling market is experiencing rapid growth. Consequently, the cascade utilization and recycling of lithium-related resources has become a pressing issue for the industry. Due to its superior performance compared to ternary lithium batteries in terms of theoretical manufacturing cost, safety, and cycle life, lithium iron phosphate (LIFP) has become one of the most widely accepted lithium-ion battery electrode materials in the market.

[0003] In recent years, the traditional process for recycling spent lithium iron phosphate batteries has combined pyrolysis with roasting. Large amounts of inorganic acid are used to dissolve the lithium iron phosphate to form a solution. This solution is then neutralized with a large amount of alkali, defluorinated with iron and aluminum salts, and dephosphorized with calcium salts to produce a lithium-containing solution. The end products of this conventional lithium recovery process are lithium carbonate and lithium hydroxide. While sodium carbonate precipitation offers low reagent costs and a simple process, the lithium yield is low, necessitating concentration to increase the lithium concentration, resulting in high recovery costs. For lithium hydroxide, the production process involves evaporation and concentration, so energy consumption is the primary cost. However, raw material costs account for 70%-80% of the process, making it susceptible to market fluctuations. Key challenges with this traditional process include high acid consumption for neutralization, large slag volumes generated by treating metal impurities and fluorine, and a lithium-rich mother liquor with high impurities that requires extensive impurity removal. Overall, this results in unacceptable byproduct levels, inefficient resource utilization, and low product value.

[0004] Currently, the traditional process for treating spent lithium iron phosphate batteries generally employs a pyrolysis pretreatment combined with hydrometallurgy. First, the lithium iron phosphate cathode material is dissolved with a large amount of inorganic acid to form a leachate. After neutralizing the excess acid with a strong base, fluoride is removed by precipitation with iron and aluminum salts, followed by phosphorus removal by precipitation with calcium salts, ultimately yielding a lithium-containing solution. The primary end products of this process are lithium carbonate and lithium hydroxide. For lithium carbonate, sodium carbonate precipitation is commonly used to recover lithium. While this method offers the advantages of low reagent costs and simple operation, the lithium yield is generally low and concentration is required to increase the lithium concentration, resulting in high recovery costs. For lithium hydroxide, the recovery process involves evaporation and concentration, resulting in a significant energy consumption component of the processing costs. Raw material costs account for 70%-80% of the total process cost, making the process susceptible to market fluctuations and difficult to ensure stable production. Furthermore, traditional processes also present challenges such as high acid consumption for acid-base neutralization, large slag volumes generated by treating metal impurities and fluoride, and the resulting lithium-rich mother liquor, which is highly impure and requires extensive impurity removal.

[0005] In view of the problems of unacceptable by-product volume, low resource utilization efficiency and low product value in traditional processes, there are two main improved processes in the existing technology:

[0006] (1) Salting roasting + selective leaching

[0007] A Chinese invention patent (publication number: CN 115893345A) discloses a method for recovering waste lithium iron phosphate / sodium iron phosphate battery cathode materials. This patent utilizes the cathode material roasted with chloride salts to extract lithium and ultimately produce lithium iron phosphate cathode materials. After the chloride salt roasting, an iron-aluminum product is first obtained. The roasted residue is then leached to obtain relatively pure lithium-containing and phosphate-containing solutions, respectively. After simple impurity removal, these two solutions are synthesized again to produce lithium iron phosphate. This process achieves low-cost resource recovery of lithium iron phosphate by recycling the chlorination reagent. However, the processing cost is high due to the steam calcination temperature and heat exchange required to recover the chloride salts. Furthermore, fluorine recovery is not considered, resulting in incomplete resource utilization.

[0008] (2) Selective leaching + extraction of lithium

[0009] A Chinese invention patent (publication number: CN 115261605A) discloses a method for recovering lithium iron phosphate. The patent describes a method for leaching lithium iron phosphate using an acidic solution and an oxidant to selectively obtain a lithium-containing leachate. This leachate, after precipitation, yields a lithium carbonate product. Following leaching, the leached residue is then leached using iron powder for copper removal and tributyl phosphate for phosphorus extraction and separation, completing the recovery of iron, phosphorus, and copper. This process is simple, resulting in a high-purity ferrophosphorus resource and easy control of each step. However, the impact of fluoride ions on product quality is not considered, and tributyl phosphate is highly water-soluble, resulting in significant losses during the extraction process.

[0010] A Chinese invention patent (CN 117163928A) discloses a method for recovering waste lithium iron phosphate materials. This patent involves leaching the lithium iron phosphate material into a ferric chloride solution, selectively obtaining a lithium-containing leachate and a crude ferric phosphate product. This leachate is then extracted and stripped with tributyl phosphate to yield a lithium chloride solution and ferric chloride. The ferric chloride is recycled, and lithium is extracted and separated with tributyl phosphate to recover lithium, iron, and phosphorus. This process has a low lithium loss rate, but the high water solubility of tributyl phosphate still presents challenges, and the removal of copper and aluminum impurities is not considered.

[0011] In summary, the existing wet recovery process for lithium iron phosphate generally has the following problems: (1) low resource recovery rate, incomplete recovery of various elements, especially the failure to consider the recovery of fluorine; (2) low lithium precipitation rate in the preparation of lithium carbonate products by precipitation; (3) large loss of the extractant; and cannot meet the requirements for full resource utilization of lithium iron phosphate. Summary of the Invention

[0012] The purpose of the present invention is to provide a waste lithium iron phosphate battery recycling process to solve the technical problems raised in the above background technology.

[0013] In order to achieve the above object, the present invention adopts the following technical solutions:

[0014] A waste lithium iron phosphate battery recycling process comprises the following steps:

[0015] S1 powder calcination: crushing and screening the waste lithium iron phosphate battery positive electrode powder and concentrated sulfuric acid in a mass ratio of 0.2 to 3.0, and calcining at 300 to 800 ° C for 0.5 to 6.0 hours to obtain a calcined material;

[0016] S2 powder leaching: the roasted material obtained in S1 is leached in water, and hydrogen peroxide is added at the same time, the molar ratio of hydrogen peroxide to lithium in the solution is controlled between 0.5 and 5.0, the reaction time is 1.0 to 4.0 hours, and sulfuric acid or sodium hydroxide solution is used throughout the process to control the solution pH between 3.0 and 7.0. After the reaction, the solution is filtered and separated to obtain a selective leachate;

[0017] S3 impurity metal extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: saponification, loaded metal extraction, washing, and organic back extraction, which are carried out in parallel and continuously. Specifically:

[0018] (1) Saponification: The newly prepared cationic extractant is thoroughly mixed with the sodium hydroxide solution, and then allowed to stand for separation to obtain a saponified organic phase and iron-containing saponified wastewater;

[0019] (2) Loaded metal extraction: the saponified organic phase is fully mixed with the selective leaching solution obtained in S2, and then allowed to stand for separation to obtain the loaded metal organic phase and the extraction residue, and the pH of the extraction residue is controlled to be 2.0-6.0;

[0020] (3) Washing: The loaded metal organic phase is thoroughly mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain an impure metal organic phase and a washing residue;

[0021] (4) Organic back-extraction: The impure metal organic phase is fully mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain a back-extracted organic phase and an impurity metal solution containing impurities such as calcium, aluminum, and copper; the back-extracted organic phase is returned to the phenolization step for reuse as an anion extractant;

[0022] S4 anion extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: phenolization, loaded anion extraction, fluorine and sulfur stripping, and phosphorus stripping, which are carried out in parallel and continuously. Specifically:

[0023] (1) Phenolation: The newly prepared anion extractant is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium chloride solution;

[0024] (2) Loaded anion extraction: the phenolized organic phase is fully mixed with the extract obtained in S3, and the pH of the extract is controlled to be 8.0-13.0, followed by centrifugation to obtain the loaded anion organic phase and the crude lithium hydroxide solution;

[0025] (3) Fluorine-sulfur stripping: the anion-loaded organic phase is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phosphorus-containing organic phase and a fluorine-containing sodium sulfate solution;

[0026] (4) Phosphorus stripping: the phosphorus-containing organic phase is fully mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium phosphate solution; the phenolized organic phase is returned to the loaded anion extraction step and reused in S5 sodium fluoride separation: the fluorine-containing sodium sulfate solution obtained in S4 is frozen and crystallized at a temperature of -10 to 10°C, and then separated to obtain a sodium sulfate decahydrate product and a sodium fluoride solution;

[0027] Preparation of S6 lithium hydroxide: Use sodium hydroxide solution to adjust the pH of the crude lithium hydroxide solution obtained in S4 to 11.0-13.0, precipitate and separate magnesium hydroxide, add sulfuric acid solution to a molar ratio of (SO4 2- ) / (Na + )=22.0 / 1.0~2.1 / 1.0, evaporate and concentrate, freeze crystallize at a temperature of -10~10°C for 1-6h, and centrifuge to obtain sodium sulfate decahydrate product and lithium hydroxide solution;

[0028] S7: Preparation of lithium hydroxide product: The lithium hydroxide solution obtained in S6 is evaporated and crystallized to obtain a lithium hydroxide product.

[0029] Furthermore, in step S3, the number of stages in each of the saponification, loaded metal extraction, washing, and organic back extraction is 2-12; in the saponification, loaded metal extraction, washing, and organic back extraction, the volume flow ratios of the organic phase and the aqueous phase are 1 / 0.02-0.10, 1 / 0.1-10.0, 1 / 0.03-1.00, and 1 / 0.03-1.00, respectively; in step S4, the number of stages in each of the phenolization, loaded anion extraction, fluorine-sulfur back extraction, and phosphorus back extraction are 2-8; in the phenolization, loaded anion extraction, fluorine-sulfur back extraction, and phosphorus back extraction, the volume flow ratios of the organic phase and the aqueous phase are 1 / 0.02-0.10, 1 / 0.1-10.0, 1 / 0.02-1.00, and 1 / 0.02-1.00, respectively.

[0030] Furthermore, in step S3, the newly configured cationic extractant is made of the following raw materials in percentage by mass: 20% to 95% of diluent, 0% to 25% of phase regulator, and 5% to 50% of main extraction component A.

[0031] Furthermore, the structure of the main extract component A is shown in Formula 1:

[0032] Formula 1:

[0033] In formula 1, R1 and R2 are each independently a linear alkyl group, a branched alkyl group or an alkoxy group having 1 to 10 carbon atoms.

[0034] Furthermore, the structure of the main extract component A is shown in Formula 2:

[0035] Formula 2:

[0036] In formula 2, R1 and R2 are each independently a linear alkyl group, a branched alkyl group or an alkoxy group having 4 to 14 carbon atoms.

[0037] Furthermore, in step S4, in step S3, the newly configured anion extractant comprises the following raw materials in percentage by mass: diluent 20% to 95%, phase regulator 0% to 50%, main extraction component B 5% to 50%, and secondary extraction component 5% to 30%.

[0038] Furthermore, the structure of the main extract component B is shown in Formula 3:

[0039] Formula 3:

[0040] In Formula 3, the anion bound to the cation is a chloride ion, and R5, R6, R7, and R8 are each independently a hydrogen atom or a linear alkyl group, a branched alkyl group, or an alkoxy group having 1 to 12 carbon atoms.

[0041] Furthermore, the structure of the secondary extraction component is shown in Formula 4:

[0042] Formula 4:

[0043] In formula 4, R9, R10, and R11 are each independently a hydrogen atom or a linear alkyl group, a branched alkyl group, or an alkoxy group having 1 to 12 carbon atoms.

[0044] Furthermore, the diluent is one or more of sulfonated kerosene, No. 260 solvent oil, n-dodecane, carbon tetrachloride, cyclohexane, and ethylbenzene.

[0045] Furthermore, the phase regulator is one or more of branched alcohols, branched phenols, branched esters, and branched ethers having 4 to 20 carbon atoms.

[0046] The principle of lithium iron phosphate battery recycling of the present invention is:

[0047] In S3, HL represents the main extracting component in the cationic extractant, M represents the metal to be extracted, and x represents the valence state of the metal to be extracted. The chemical equation is:

[0048] Saponification and loaded metal extraction process: xHL+M x+ ===xH + +ML x

[0049] Washing and organic back extraction process: xH + +ML x ===xHL+M x+

[0050] In S4, B·Cl represents the main extracting component in the anion extractant, X represents the extracted anion, and z represents the valence state of the extracted anion.

[0051] Phenolation process: B·Cl+OH - = = = B·OH+Cl -

[0052] Loaded anion extraction process: zB·OH+X z- = = = B z ·X+zOH -

[0053] Fluorine and sulfur stripping, phosphorus stripping process: B z ·X+zOH - = = = zB·OH+X z-

[0054] The beneficial effects of the present invention compared to the prior art are:

[0055] (1) The process of the present invention adopts an anionic extractant to recover and separate phosphorus, fluorine and sulfur elements in the system by ion exchange. This extractant introduces almost no impurity elements during recycling and can recover fluorine and phosphorus elements in the solution to the greatest extent, effectively improving the level of resource utilization.

[0056] (2) The extractant and organic solvent used in the process of the present invention can be fully recycled, and the anion extractant has low water solubility, which improves the economic value of the process through better recycling effect.

[0057] (3) The process of the present invention has high selectivity for each element and high leaching efficiency, and the final product is lithium hydroxide, which overcomes the problems of low precipitation rate of lithium carbonate and limited output rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0059] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and by way of preferred embodiments. However, it should be noted that many of the details listed in this specification are merely provided to help the reader gain a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be practiced even without these specific details.

[0060] like Figure 1 As shown, a waste lithium iron phosphate battery recycling process includes the following steps:

[0061] S1 powder calcination: crushing and screening the waste lithium iron phosphate battery positive electrode powder and concentrated sulfuric acid in a mass ratio of 0.2 to 3.0, and calcining at 300 to 800 ° C for 0.5 to 6.0 hours to obtain a calcined material;

[0062] S2 powder leaching: the roasted material obtained in S1 is leached in water, and hydrogen peroxide is added at the same time, the molar ratio of hydrogen peroxide to lithium in the solution is controlled between 0.5 and 5.0, the reaction time is 1.0 to 4.0 hours, and sulfuric acid or sodium hydroxide solution is used throughout the process to control the solution pH between 3.0 and 7.0. After the reaction, the solution is filtered and separated to obtain a selective leachate;

[0063] S3 impurity metal extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: saponification, loaded metal extraction, washing, and organic back extraction, which are carried out in parallel and continuously. Specifically:

[0064] (1) Saponification: The newly prepared cationic extractant is fully mixed with the sodium hydroxide solution, and then allowed to stand for separation to obtain a saponified organic phase and iron-containing saponified wastewater; the number of stages is 2-12; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.02-0.10;

[0065] (2) Loaded metal extraction: The saponified organic phase is fully mixed with the selective leaching solution obtained in S2, and then allowed to stand for separation to obtain a metal-loaded organic phase and an extraction residue, and the pH of the extraction residue is controlled to be 2.0 to 6.0; the number of stages is 2 to 12; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.1 to 10.0;

[0066] (3) Washing: The loaded metal organic phase is thoroughly mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain an impure metal organic phase and a washing residual liquid; the number of stages is 2-12; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.03 to 1.00;

[0067] (4) Organic back extraction: The impure metal organic phase is fully mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain a back extraction organic phase and an impurity metal solution containing impurities such as calcium, aluminum, and copper; the back extraction organic phase is reused in the phenolization step as an anion extractant; the number of stages is 2-12; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.03 to 1.00;

[0068] S4 anion extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: phenolization, loaded anion extraction, fluorine and sulfur stripping, and phosphorus stripping, which are carried out in parallel and continuously. Specifically:

[0069] (1) Phenolation: A newly prepared anion extractant is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium chloride solution; the number of stages is 2-8; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.02-0.10;

[0070] (2) Loaded anion extraction: the phenolized organic phase is fully mixed with the extract raffinate obtained in S3, and the pH of the extract raffinate is controlled to be 8.0-13.0, followed by centrifugation to obtain the loaded anion organic phase and the crude lithium hydroxide solution; the number of stages is 2-8; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.1-10.0;

[0071] (3) Fluorine-sulfur stripping: the anion-loaded organic phase is fully mixed with a sodium hydroxide solution, and then centrifuged to obtain a phosphorus-containing organic phase and a fluorine-containing sodium sulfate solution; the number of stages is 2-8; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.02 to 1.00;

[0072] (4) Phosphorus stripping: The phosphorus-containing organic phase is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium phosphate solution; the phenolized organic phase is returned to the anion-loaded extraction step for repeated use; the number of stages is 2-8; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.02 to 1.00;

[0073] S5 sodium fluoride separation: freezing and crystallizing the fluorine-containing sodium sulfate solution obtained in S4 at a temperature of -10 to 10° C., and separating to obtain sodium sulfate decahydrate product and sodium fluoride solution;

[0074] Preparation of S6 lithium hydroxide: Use sodium hydroxide solution to adjust the pH of the crude lithium hydroxide solution obtained in S4 to 11.0-13.0, precipitate and separate magnesium hydroxide, add sulfuric acid solution to a molar ratio of (SO4 2- ) / (Na + )=22.0 / 1.0~2.1 / 1.0, evaporate and concentrate, freeze crystallize at a temperature of -10~10°C for 1-6h, and centrifuge to obtain sodium sulfate decahydrate product and lithium hydroxide solution;

[0075] S7: Preparation of lithium hydroxide product: The lithium hydroxide solution obtained in S6 is evaporated and crystallized to obtain a lithium hydroxide product.

[0076] In step S3, the newly configured cationic extractant is prepared by mixing the following raw materials in percentage by mass: 20% to 95% of diluent, 0% to 25% of phase regulator, and 5% to 50% of main extraction component A.

[0077] The structure of the main extract component A is shown in Formula 1 or Formula 2:

[0078] Formula 1:

[0079] In formula 1, R1 and R2 are each independently a linear alkyl group, a branched alkyl group or an alkoxy group having 1 to 10 carbon atoms.

[0080] Formula 2:

[0081] In formula 2, R1 and R2 are each independently a linear alkyl group, a branched alkyl group or an alkoxy group having 4 to 14 carbon atoms.

[0082] In step S4, in step S3, the newly configured anion extractant is prepared by mixing the following raw materials in the following mass percentages: 20% to 95% diluent, 0% to 50% phase regulator, 5% to 50% main extraction component B, and 5% to 30% secondary extraction component.

[0083] The structure of the main extract component B is shown in Formula 3:

[0084] Formula 3:

[0085] In Formula 3, the anion bound to the cation is a chloride ion, and R5, R6, R7, and R8 are each independently a hydrogen atom or a linear alkyl group, a branched alkyl group, or an alkoxy group having 1 to 12 carbon atoms.

[0086] The structure of the secondary extraction component is shown in Formula 4:

[0087] Formula 4:

[0088] In formula 4, R9, R10, and R11 are each independently a hydrogen atom or a linear alkyl group, a branched alkyl group, or an alkoxy group having 1 to 12 carbon atoms.

[0089] The diluent is one or more of sulfonated kerosene, No. 260 solvent oil, n-dodecane, carbon tetrachloride, cyclohexane, and ethylbenzene.

[0090] The phase regulator is one or more of branched alcohols, branched phenols, branched esters and branched ethers having 4 to 20 carbon atoms.

[0091] The following is described by more specific embodiments:

[0092] Example 1

[0093] A waste lithium iron phosphate battery recycling process comprises the following steps:

[0094] S1 powder calcination: crushed and sieved waste lithium iron phosphate battery positive electrode powder is mixed with concentrated sulfuric acid at a mass ratio of 0.8, and calcined at 650°C for 1.5 hours to obtain a calcined material;

[0095] S2 powder leaching: the roasted material obtained in S1 is leached in water, and hydrogen peroxide is added at the same time, the molar ratio of hydrogen peroxide to lithium in the solution is controlled to be 3, the reaction time is 2 hours, and the pH of the solution is controlled to be 4 using sulfuric acid or sodium hydroxide solution throughout the reaction. After the reaction, the solution is filtered and separated to obtain a selective leachate;

[0096] S3 impurity metal extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: saponification, loaded metal extraction, washing, and organic back extraction, which are carried out in parallel and continuously. Specifically:

[0097] (1) Saponification: The newly prepared cationic extractant is fully mixed with the sodium hydroxide solution, and then allowed to stand for separation to obtain a saponified organic phase and iron-containing saponified wastewater; the number of stages is 2; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.03;

[0098] (2) Loaded metal extraction: The saponified organic phase is fully mixed with the selective leaching solution obtained in S2, and then allowed to stand for separation to obtain a metal-loaded organic phase and an extraction residue, and the pH of the extraction residue is controlled to be 4.1; the number of stages is 12; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.4;

[0099] (3) Washing: The loaded metal organic phase is thoroughly mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain an impure metal organic phase and a washing residual liquid; the number of stages is 12; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.1;

[0100] (4) Organic back extraction: The impure metal organic phase is fully mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain a back extraction organic phase and an impurity metal solution containing impurities such as calcium, aluminum, and copper; the back extraction organic phase is reused in the phenolization step as an anion extractant; the number of stages is 6; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.2;

[0101] S4 anion extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: phenolization, loaded anion extraction, fluorine and sulfur stripping, and phosphorus stripping, which are carried out in parallel and continuously. Specifically:

[0102] (1) Phenolation: A newly prepared anion extractant was thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium chloride solution; the number of stages was 2; the volume flow ratio of the organic phase to the aqueous phase was 1 / 0.02;

[0103] (2) Loaded anion extraction: The phenolized organic phase was fully mixed with the extract raffinate obtained in S3, and the pH of the extract raffinate was controlled to 12, followed by centrifugation to obtain the loaded anion organic phase and the crude lithium hydroxide solution; the number of stages was 6; the volume flow ratio of the organic phase to the aqueous phase was 1 / 0.4;

[0104] (3) Fluorine-sulfur stripping: the anion-loaded organic phase is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phosphorus-containing organic phase and a fluorine-containing sodium sulfate solution; the number of stages is 8; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.05;

[0105] (4) Phosphorus stripping: The phosphorus-containing organic phase is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium phosphate solution; the phenolized organic phase is returned to the anion-loaded extraction step for reuse; the number of stages is 4; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.5;

[0106] S5 Sodium fluoride separation: The fluorine-containing sodium sulfate solution obtained in S4 is frozen and crystallized at -5°C for 2 hours to separate the sodium sulfate decahydrate product and the sodium fluoride solution;

[0107] Preparation of S6 lithium hydroxide: The pH of the crude lithium hydroxide solution obtained in S4 was adjusted to 13.0 using sodium hydroxide solution, and after precipitation and separation of magnesium hydroxide, sulfuric acid solution was added to a molar ratio of (SO4 2- ) / (Na + )=2.02 / 1.0, evaporate and concentrate, freeze crystallize at -5°C for 2h, and centrifuge to obtain sodium sulfate decahydrate product and lithium hydroxide solution;

[0108] S7: Preparation of lithium hydroxide product: The lithium hydroxide solution obtained in S6 is evaporated and crystallized to obtain a lithium hydroxide product.

[0109] In step S3, the newly configured cationic extractant is prepared by mixing the following raw materials in percentage by mass: 40% sulfonated kerosene, 40% lauryl alcohol, and 20% 2-ethylhexyl mono-2-ethylhexyl phosphate.

[0110] In step S4, in step S3, the newly configured anion extractant is prepared by mixing the following raw materials in percentage by mass: 60% cyclohexane, 10% lauryl alcohol, 20% tetraoctylammonium chloride, and 10% 2-ethoxy-4-(methoxymethyl)phenol.

[0111] Example 2

[0112] A waste lithium iron phosphate battery recycling process comprises the following steps:

[0113] S1 powder calcination: crushed and sieved waste lithium iron phosphate battery positive electrode powder is mixed with concentrated sulfuric acid at a mass ratio of 1.2, and calcined at 700°C for 2 hours to obtain a calcined material;

[0114] S2 powder leaching: the roasted material obtained in S1 is leached in water, and hydrogen peroxide is added at the same time, the molar ratio of hydrogen peroxide to lithium in the solution is controlled to be between 2, the reaction time is 1 hour, and sulfuric acid or sodium hydroxide solution is used throughout the process to control the solution pH to 6. After the reaction, the solution is filtered and separated to obtain a selective leachate;

[0115] S3 impurity metal extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: saponification, loaded metal extraction, washing, and organic back extraction, which are carried out in parallel and continuously. Specifically:

[0116] (1) Saponification: The newly prepared cationic extractant is fully mixed with the sodium hydroxide solution, and then allowed to stand for separation to obtain a saponified organic phase and iron-containing saponified wastewater; the number of stages is 2; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.05;

[0117] (2) Loaded metal extraction: The saponified organic phase is fully mixed with the selective leaching solution obtained in S2, and then allowed to stand for separation to obtain a metal-loaded organic phase and an extraction residue, and the pH of the extraction residue is controlled to be 3.5; the number of stages is 10; the volume flow ratio of the organic phase to the aqueous phase is 1 / 1;

[0118] (3) Washing: The loaded metal organic phase is thoroughly mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain an impure metal organic phase and a washing residual liquid; the number of stages is 8; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.08;

[0119] (4) Organic back extraction: The impure metal organic phase is fully mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain a back extraction organic phase and an impurity metal solution containing impurities such as calcium, aluminum, and copper; the back extraction organic phase is reused in the phenolization step as an anion extractant; the number of stages is 4; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.1;

[0120] S4 anion extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: phenolization, loaded anion extraction, fluorine and sulfur stripping, and phosphorus stripping, which are carried out in parallel and continuously. Specifically:

[0121] (1) Phenolation: A newly prepared anion extractant was thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium chloride solution; the number of stages was 2; the volume flow ratio of the organic phase to the aqueous phase was 1 / 0.03;

[0122] (2) Loaded anion extraction: The phenolized organic phase was fully mixed with the extractant obtained in S3, and the pH of the extractant was controlled to 11, followed by centrifugation to obtain the loaded anion organic phase and the crude lithium hydroxide solution; the number of stages was 6; the volume flow ratio of the organic phase to the aqueous phase was 1 / 1;

[0123] (3) Fluorine-sulfur stripping: the anion-loaded organic phase is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phosphorus-containing organic phase and a fluorine-containing sodium sulfate solution; the number of stages is 8; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.1;

[0124] (4) Phosphorus stripping: The phosphorus-containing organic phase is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium phosphate solution; the phenolized organic phase is returned to the anion-loaded extraction step for reuse; the number of stages is 4; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.8;

[0125] S5 Sodium fluoride separation: The fluorine-containing sodium sulfate solution obtained in S4 is frozen and crystallized at -2°C for 4 hours to separate the sodium sulfate decahydrate product and the sodium fluoride solution;

[0126] Preparation of lithium hydroxide S6: The pH of the crude lithium hydroxide solution obtained in S4 was adjusted to 12.5 using sodium hydroxide solution, and after precipitation and separation of magnesium hydroxide, sulfuric acid solution was added to a molar ratio of (SO4 2- ) / (Na + )=2.0 / 1.0, evaporate and concentrate, freeze crystallize at -2°C for 1h, and centrifuge to obtain sodium sulfate decahydrate product and lithium hydroxide solution;

[0127] S7: Preparation of lithium hydroxide product: The lithium hydroxide solution obtained in S6 is evaporated and crystallized to obtain a lithium hydroxide product.

[0128] In step S3, the newly configured cationic extractant is prepared by mixing the following raw materials in percentage by mass: 70% sulfonated kerosene, 20% nonylphenol, and 10% di(2,4,4-trimethylpentyl)phosphinic acid.

[0129] In step S4, in step S3, the newly configured anion extractant is prepared by mixing the following raw materials in percentage by mass: 60% sulfonated kerosene, 20% lauryl alcohol, 8% tetraoctylammonium chloride, and 12% 4-tert-butylphenol.

[0130] Example 3

[0131] A waste lithium iron phosphate battery recycling process comprises the following steps:

[0132] S1 powder calcination: crushed and sieved waste lithium iron phosphate battery positive electrode powder is mixed with concentrated sulfuric acid at a mass ratio of 0.2, and calcined at 800°C for 4 hours to obtain a calcined material;

[0133] S2 powder leaching: the roasted material obtained in S1 is leached in water, and hydrogen peroxide is added at the same time, the molar ratio of hydrogen peroxide to lithium in the solution is controlled between 5, the reaction time is 3 hours, and sulfuric acid or sodium hydroxide solution is used throughout the process to control the solution pH to 7. After the reaction, the solution is filtered and separated to obtain a selective leachate;

[0134] S3 impurity metal extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: saponification, loaded metal extraction, washing, and organic back extraction, which are carried out in parallel and continuously. Specifically:

[0135] (1) Saponification: The newly prepared cationic extractant was fully mixed with the sodium hydroxide solution, and then allowed to stand for separation to obtain a saponified organic phase and iron-containing saponified wastewater; the number of stages was 12; the volume flow ratio of the organic phase to the aqueous phase was 1 / 0.02;

[0136] (2) Loaded metal extraction: The saponified organic phase is fully mixed with the selective leachate obtained in S2, and then allowed to stand for separation to obtain a metal-loaded organic phase and an extraction residue, and the pH of the extraction residue is controlled to be 6; the number of stages is 12; the volume flow ratio of the organic phase to the aqueous phase is 1 / 10;

[0137] (3) Washing: The loaded metal organic phase is thoroughly mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain an impure metal organic phase and a washing residual liquid; the number of stages is 4; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.05;

[0138] (4) Organic back extraction: The impure metal organic phase is fully mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain a back extraction organic phase and an impurity metal solution containing impurities such as calcium, aluminum, and copper; the back extraction organic phase is reused in the phenolization step as an anion extractant; the number of stages is 5; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.03;

[0139] S4 anion extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: phenolization, loaded anion extraction, fluorine and sulfur stripping, and phosphorus stripping, which are carried out in parallel and continuously. Specifically:

[0140] (1) Phenolation: A newly prepared anion extractant was thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium chloride solution; the number of stages was 8; the volume flow ratio of the organic phase to the aqueous phase was 1 / 0.1;

[0141] (2) Loaded anion extraction: The phenolized organic phase was fully mixed with the extractant obtained in S3, and the pH of the extractant was controlled to 10, followed by centrifugation to obtain the loaded anion organic phase and the crude lithium hydroxide solution; the number of stages was 8; the volume flow ratio of the organic phase to the aqueous phase was 1 / 10;

[0142] (3) Fluorine-sulfur stripping: the anion-loaded organic phase is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phosphorus-containing organic phase and a fluorine-containing sodium sulfate solution; the number of stages is 5; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.02;

[0143] (4) Phosphorus stripping: The phosphorus-containing organic phase is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium phosphate solution; the phenolized organic phase is returned to the anion-loaded extraction step for repeated use; the number of stages is 5; the volume flow ratio of the organic phase to the aqueous phase is 1 / 1;

[0144] S5: Sodium fluoride separation: The fluorine-containing sodium sulfate solution obtained in S4 is frozen and crystallized at 10°C for 3 hours to separate the sodium sulfate decahydrate product and the sodium fluoride solution;

[0145] Preparation of lithium hydroxide S6: The pH of the crude lithium hydroxide solution obtained in S4 was adjusted to 11.5 using sodium hydroxide solution, and after precipitation and separation of magnesium hydroxide, sulfuric acid solution was added to a molar ratio of (SO4 2- ) / (Na + )=2.05 / 1.0, evaporate and concentrate, freeze crystallize at -10°C for 4h, and centrifuge to obtain sodium sulfate decahydrate product and lithium hydroxide solution;

[0146] S7: Preparation of lithium hydroxide product: The lithium hydroxide solution obtained in S6 is evaporated and crystallized to obtain a lithium hydroxide product.

[0147] In step S3, the newly configured cationic extractant is prepared by mixing the following raw materials in percentage by mass: 60% of n-dodecane, 20% of sec-octanol, and 20% of 2-methyl-2-ethyl-octanoic acid.

[0148] In step S4, in step S3, the newly configured anion extractant is prepared by mixing the following raw materials in percentage by mass: 70% cyclohexane, 10% isooctyl alcohol, 10% triisooctylmethylammonium chloride, and 10% 2,6-dimethylphenol.

[0149] Example 4

[0150] A waste lithium iron phosphate battery recycling process comprises the following steps:

[0151] S1 powder calcination: crushed and sieved waste lithium iron phosphate battery positive electrode powder is mixed with concentrated sulfuric acid at a mass ratio of 2.5, and calcined at 500°C for 6 hours to obtain a calcined material;

[0152] S2 powder leaching: the roasted material obtained in S1 is leached in water, and hydrogen peroxide is added at the same time, and the molar ratio of hydrogen peroxide to lithium in the solution is controlled between 0.5. The reaction time is 4 hours, and the pH of the solution is controlled at 3 using sulfuric acid or sodium hydroxide solution throughout the reaction. After the reaction, the solution is filtered and separated to obtain a selective leachate;

[0153] S3 impurity metal extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: saponification, loaded metal extraction, washing, and organic back extraction, which are carried out in parallel and continuously. Specifically:

[0154] (1) Saponification: The newly prepared cationic extractant was fully mixed with the sodium hydroxide solution, and then allowed to stand for separation to obtain a saponified organic phase and iron-containing saponified wastewater; the number of stages was 8; the volume flow ratio of the organic phase to the aqueous phase was 1 / 0.08;

[0155] (2) Loaded metal extraction: The saponified organic phase is fully mixed with the selective leachate obtained in S2, and then allowed to stand for separation to obtain a metal-loaded organic phase and an extraction residue, and the pH of the extraction residue is controlled to be 3; the number of stages is 2; the volume flow ratio of the organic phase to the aqueous phase is 1 / 3;

[0156] (3) Washing: The loaded metal organic phase is thoroughly mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain an impure metal organic phase and a washing residual liquid; the number of stages is 12; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.03;

[0157] (4) Organic back extraction: The impure metal organic phase is fully mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain a back extraction organic phase and an impurity metal solution containing impurities such as calcium, aluminum, and copper; the back extraction organic phase is reused in the phenolization step as an anion extractant; the number of stages is 12; the volume flow ratio of the organic phase to the aqueous phase is 1 / 1;

[0158] S4 anion extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: phenolization, loaded anion extraction, fluorine and sulfur stripping, and phosphorus stripping, which are carried out in parallel and continuously. Specifically:

[0159] (1) Phenolation: A newly prepared anion extractant was thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium chloride solution; the number of stages was 4; the volume flow ratio of the organic phase to the aqueous phase was 1 / 0.06;

[0160] (2) Loaded anion extraction: The phenolized organic phase was fully mixed with the extract raffinate obtained in S3, and the pH of the extract raffinate was controlled to 13, followed by centrifugation to obtain the loaded anion organic phase and the crude lithium hydroxide solution; the number of stages was 2; the volume flow ratio of the organic phase to the aqueous phase was 1 / 0.1;

[0161] (3) Fluorine-sulfur stripping: the anion-loaded organic phase is fully mixed with a sodium hydroxide solution, and then centrifuged to obtain a phosphorus-containing organic phase and a fluorine-containing sodium sulfate solution; the number of stages is 3; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.4;

[0162] (4) Phosphorus stripping: The phosphorus-containing organic phase is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium phosphate solution; the phenolized organic phase is returned to the anion-loaded extraction step for reuse; the number of stages is 2; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.02;

[0163] S5 Sodium fluoride separation: The fluorine-containing sodium sulfate solution obtained in S4 is frozen and crystallized at -10°C for 4 hours to separate the sodium sulfate decahydrate product and the sodium fluoride solution;

[0164] Preparation of S6 lithium hydroxide: The pH of the crude lithium hydroxide solution obtained in S4 was adjusted to 13 using sodium hydroxide solution, and after precipitation and separation of magnesium hydroxide, sulfuric acid solution was added to a molar ratio of (SO4 2- ) / (Na + )=2.1 / 1.0, evaporate and concentrate, freeze crystallize at a temperature of 10° C. for 6 h, and centrifuge to obtain sodium sulfate decahydrate product and lithium hydroxide solution;

[0165] S7: Preparation of lithium hydroxide product: The lithium hydroxide solution obtained in S6 is evaporated and crystallized to obtain a lithium hydroxide product.

[0166] In step S3, the newly configured cationic extractant is prepared by mixing the following raw materials in percentage by mass: 40% of n-dodecane, 20% of isobutyl isooctanoate, and 40% of 2-methyl-2-ethyl-hexanoic acid.

[0167] In step S4, in step S3, the newly configured anion extractant is prepared by mixing the following raw materials in percentage by mass: 80% of n-dodecane, 5% of isobutyl isooctanoate, 8% of tetrabutylammonium chloride, and 7% of 4-tert-butylphenol.

[0168] Example 5

[0169] A waste lithium iron phosphate battery recycling process comprises the following steps:

[0170] S1 Powder Calcination: Mix the crushed and sieved waste lithium iron phosphate battery positive electrode powder with concentrated sulfuric acid in a mass ratio of 3, and calcine at 300°C for 0.5 hours to obtain a calcined material;

[0171] S2 powder leaching: the roasted material obtained in S1 is leached in water, and hydrogen peroxide is added at the same time, the molar ratio of hydrogen peroxide to lithium in the solution is controlled to be between 4, the reaction time is 2 hours, and sulfuric acid or sodium hydroxide solution is used throughout the process to control the solution pH to 5. After the reaction, the solution is filtered and separated to obtain a selective leachate;

[0172] S3 impurity metal extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: saponification, loaded metal extraction, washing, and organic back extraction, which are carried out in parallel and continuously. Specifically:

[0173] (1) Saponification: The newly prepared cationic extractant was fully mixed with the sodium hydroxide solution, and then allowed to stand for separation to obtain a saponified organic phase and iron-containing saponified wastewater; the number of stages was 10; the volume flow ratio of the organic phase to the aqueous phase was 1 / 0.1;

[0174] (2) Loaded metal extraction: The saponified organic phase is fully mixed with the selective leaching solution obtained in S2, and then allowed to stand for separation to obtain a metal-loaded organic phase and an extraction residue, and the pH of the extraction residue is controlled to be 2; the number of stages is 8; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.1;

[0175] (3) Washing: The loaded metal organic phase is thoroughly mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain an impure metal organic phase and a washing residual liquid; the number of stages is 2; the volume flow ratio of the organic phase to the aqueous phase is 1 / 1;

[0176] (4) Organic back extraction: The impure metal organic phase is fully mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain a back extraction organic phase and an impurity metal solution containing impurities such as calcium, aluminum, and copper; the back extraction organic phase is reused in the phenolization step as an anion extractant; the number of stages is 2; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.08;

[0177] S4 anion extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: phenolization, loaded anion extraction, fluorine and sulfur stripping, and phosphorus stripping, which are carried out in parallel and continuously. Specifically:

[0178] (1) Phenolation: A newly prepared anion extractant was thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium chloride solution; the number of stages was 6; the volume flow ratio of the organic phase to the aqueous phase was 1 / 0.08;

[0179] (2) Loaded anion extraction: The phenolized organic phase is fully mixed with the extract raffinate obtained in S3, and the pH of the extract raffinate is controlled to 8, followed by centrifugation to obtain the loaded anion organic phase and the crude lithium hydroxide solution; the number of stages is 4; the volume flow ratio of the organic phase to the aqueous phase is 1 / 4;

[0180] (3) Fluorine-sulfur stripping: the anion-loaded organic phase is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phosphorus-containing organic phase and a fluorine-containing sodium sulfate solution; the number of stages is 2; the volume flow ratio of the organic phase to the aqueous phase is 1 / 1;

[0181] (4) Phosphorus stripping: The phosphorus-containing organic phase is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium phosphate solution; the phenolized organic phase is returned to the anion-loaded extraction step for repeated use; the number of stages is 8; the volume flow ratio of the organic phase to the aqueous phase is 1 / 0.06;

[0182] S5 Sodium fluoride separation: The fluorine-containing sodium sulfate solution obtained in S4 is frozen and crystallized at 5°C for 2 hours to separate the sodium sulfate decahydrate product and the sodium fluoride solution;

[0183] Preparation of S6 lithium hydroxide: Use sodium hydroxide solution to adjust the pH of the crude lithium hydroxide solution obtained in S4 to 11, precipitate and separate magnesium hydroxide, add sulfuric acid solution to a molar ratio of (SO4 2- ) / (Na + )=2.07 / 1.0, evaporate and concentrate, freeze crystallize at a temperature of 2° C. for 5 h, and centrifuge to obtain sodium sulfate decahydrate product and lithium hydroxide solution;

[0184] S7: Preparation of lithium hydroxide product: The lithium hydroxide solution obtained in S6 is evaporated and crystallized to obtain a lithium hydroxide product.

[0185] In step S3, the newly configured cationic extractant is prepared by mixing the following raw materials in percentage by mass: 60% of No. 260 solvent oil, 10% of isotridecyl alcohol, and 30% of 2,5-dimethyl-2-ethylhexanoic acid.

[0186] In step S4, in step S3, the newly configured anion extractant is prepared by mixing the following raw materials in percentage by mass: 50% ethylbenzene, 30% methyl decanoate, 15% tetrahexyl ammonium chloride, and 5% 2,4,6-trimethylphenol.

[0187] 1. Lithium hydroxide product indicators

[0188] The lithium hydroxide product prepared in Example 1-2 was tested and compared with commercially available lithium hydroxide. The results are shown in Table 1:

[0189] Table 1 Lithium hydroxide index (mass fraction wt%) (impurity content, not more than)

[0190]

[0191] It can be seen from Tables 1 and 2 that the impurity content in the lithium hydroxide products in the examples is close to that of commercially available lithium hydroxide products, which meets the product requirements of lithium hydroxide monohydrate, indicating that the anion recovery capacity of the process is significant.

[0192] 2. Yield Experiment

[0193] The recovery rates of various elements in Example 1-2 and the traditional lithium iron phosphate wet recovery process were tested, and the results are shown in Table 2.

[0194] Table 2 Recovery rate of each element / %

[0195]

[0196]

[0197] As can be seen from Table 2, the recovery rates of each element in Example 1 and Example 2 are higher than those in the traditional roasting + acid selective leaching process, and the process has the ability to recover fluorine.

[0198] 3. Extractant loss experiment

[0199] The loss of active ingredients of the cationic extractant and the anionic extractant in Example 1-2 was tested at a certain operating time. The results are shown in Table 3.

[0200] Table 3 Loss of active ingredients in the extractant

[0201]

[0202] As can be seen from Table 3, the loss of active ingredients in the extractant is less than 5% within 200 days of operation, which can significantly reduce the process cost.

[0203] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A waste lithium iron phosphate battery recycling process, characterized in that: The following steps are involved: S1 powder calcination: crushing and screening the waste lithium iron phosphate battery positive electrode powder and concentrated sulfuric acid in a mass ratio of 0.2 to 3.0, and calcining at 300 to 800 ° C for 0.5 to 6.0 hours to obtain a calcined material; S2 powder leaching: the roasted material obtained in S1 is leached in water, and hydrogen peroxide is added at the same time, the molar ratio of hydrogen peroxide to lithium in the solution is controlled between 0.5 and 5.0, the reaction time is 1.0 to 4.0 hours, and sulfuric acid or sodium hydroxide solution is used throughout the process to control the solution pH between 3.0 and 7.

0. After the reaction, the solution is filtered and separated to obtain a selective leachate; S3 impurity metal extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: saponification, loaded metal extraction, washing, and organic back extraction, which are carried out in parallel and continuously. Specifically: (1) Saponification: The newly prepared cationic extractant is thoroughly mixed with the sodium hydroxide solution, and then allowed to stand for separation to obtain a saponified organic phase and iron-containing saponified wastewater; (2) Loaded metal extraction: the saponified organic phase is fully mixed with the selective leaching solution obtained in S2, and then allowed to stand for separation to obtain the loaded metal organic phase and the extraction residue, and the pH of the extraction residue is controlled to be 2.0-6.0; (3) Washing: The loaded metal organic phase is thoroughly mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain an impure metal organic phase and a washing residue; (4) Organic back-extraction: The impure metal organic phase is fully mixed with a dilute sulfuric acid solution, and then allowed to stand for separation to obtain a back-extracted organic phase and an impurity metal solution containing impurities such as calcium, aluminum, and copper; the back-extracted organic phase is returned to the phenolization step for reuse as an anion extractant; S4 anion extraction: The entire process is a multi-stage countercurrent extraction, which is divided into four steps: phenolization, loaded anion extraction, fluorine and sulfur stripping, and phosphorus stripping, which are carried out in parallel and continuously. Specifically: (1) Phenolation: The newly prepared anion extractant is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium chloride solution; (2) Loaded anion extraction: the phenolized organic phase is fully mixed with the extract obtained in S3, and the pH of the extract is controlled to be 8.0-13.0, followed by centrifugation to obtain the loaded anion organic phase and the crude lithium hydroxide solution; (3) Fluorine-sulfur stripping: the anion-loaded organic phase is thoroughly mixed with a sodium hydroxide solution, and then centrifuged to obtain a phosphorus-containing organic phase and a fluorine-containing sodium sulfate solution; (4) Phosphorus stripping: the phosphorus-containing organic phase is fully mixed with a sodium hydroxide solution, and then centrifuged to obtain a phenolized organic phase and a sodium phosphate solution; the phenolized organic phase is returned to the loaded anion extraction step and reused in S5 sodium fluoride separation: the fluorine-containing sodium sulfate solution obtained in S4 is frozen and crystallized at a temperature of -10 to 10°C, and then separated to obtain a sodium sulfate decahydrate product and a sodium fluoride solution; Preparation of S6 lithium hydroxide: Use sodium hydroxide solution to adjust the pH of the crude lithium hydroxide solution obtained in S4 to 11.0-13.0, precipitate and separate magnesium hydroxide, add sulfuric acid solution to a molar ratio of (SO4 2- ) / (Na + )=22.0 / 1.0~2.1 / 1.0, evaporate and concentrate, freeze crystallize at a temperature of -10~10°C for 1-6h, and centrifuge to obtain sodium sulfate decahydrate product and lithium hydroxide solution; S7: Preparation of lithium hydroxide product: The lithium hydroxide solution obtained in S6 is evaporated and crystallized to obtain a lithium hydroxide product.

2. A waste lithium iron phosphate battery recycling process according to claim 1, characterized in that: In step S3, the number of stages in each of the saponification, loaded metal extraction, washing, and organic back extraction is 2-12; in the saponification, loaded metal extraction, washing, and organic back extraction, the volume flow ratios of the organic phase and the aqueous phase are 1 / 0.02-0.10, 1 / 0.1-10.0, 1 / 0.03-1.00, and 1 / 0.03-1.00, respectively; in step S4, the number of stages in each of the phenolization, loaded anion extraction, fluorine-sulfur back extraction, and phosphorus back extraction are 2-8; in the phenolization, loaded anion extraction, fluorine-sulfur back extraction, and phosphorus back extraction, the volume flow ratios of the organic phase and the aqueous phase are 1 / 0.02-0.10, 1 / 0.1-10.0, 1 / 0.02-1.00, and 1 / 0.02-1.00, respectively.

3. The waste lithium iron phosphate battery recycling process according to claim 1, characterized in that: In step S3, the newly configured cationic extractant is made of the following raw materials in percentage by mass: 40-70% diluent, 10-40% phase regulator, and 10-40% main extraction component A.

4. A waste lithium iron phosphate battery recycling process according to claim 3, characterized in that: The structure of the main extract component A is shown in Formula 1: Formula 1: In formula 1, R1 and R2 are each independently a linear alkyl group, a branched alkyl group or an alkoxy group having 4 to 14 carbon atoms.

5. The waste lithium iron phosphate battery recycling process according to claim 3, characterized in that: The structure of the main extract component A is shown in Formula 2: Formula 2: In formula 2, R1 and R2 are each independently a linear alkyl group, a branched alkyl group or an alkoxy group having 1 to 10 carbon atoms.

6. The waste lithium iron phosphate battery recycling process according to claim 1, characterized in that: In step S4, in step S3, the newly configured anion extractant comprises the following raw materials in percentage by weight: diluent 50% to 80%, phase regulator 5% to 30%, main extraction component B 8% to 20%, and secondary extraction component 5% to 12%.

7. A waste lithium iron phosphate battery recycling process according to claim 6, characterized in that: The structure of the main extract component B is shown in Formula 3: Formula 3: In Formula 3, the anion bound to the cation is a chloride ion, and R5, R6, R7, and R8 are each independently a hydrogen atom or a linear alkyl group, a branched alkyl group, or an alkoxy group having 1 to 12 carbon atoms.

8. A waste lithium iron phosphate battery recycling process according to claim 7, characterized in that: The structure of the secondary extraction component is shown in Formula 4: Formula 4: In formula 4, R9, R10, and R11 are each independently a hydrogen atom or a linear alkyl group, a branched alkyl group, or an alkoxy group having 1 to 12 carbon atoms.

9. A waste lithium iron phosphate battery recycling process according to claim 3 or 6, characterized in that: The diluent is one of sulfonated kerosene, No. 260 solvent oil, n-dodecane, carbon tetrachloride, cyclohexane, and ethylbenzene.

10. A waste lithium iron phosphate battery recycling process according to claim 3 or 6, characterized in that: The phase regulator is one or more of branched alcohols, branched phenols, branched esters and branched ethers having 4 to 20 carbon atoms.

Images