Method for comprehensively recycling waste lithium battery powder and application thereof

Abstract

The invention provides a method for comprehensively recycling waste lithium battery powder, which comprises the following steps: S1, mixing first battery powder with first acid liquor to carry out acid dissolution reaction, and carrying out solid-liquid separation to obtain first solid slag and reaction liquid; s2, second battery powder and the reaction liquid are mixed for a first-stage oxidation-reduction reaction, and second solid residues and first lithium liquid are obtained after solid-liquid separation; and S3, third battery powder and the first lithium liquid are mixed for a second-stage oxidation-reduction reaction, and third solid residues and second lithium liquid are obtained after solid-liquid separation. The method can solve the problems of high production cost, low valuable metal recovery rate, difficulty in operation, difficulty in lithium liquid impurity removal and the like in the leaching process of recovering the battery powder by a wet method, and can recover various types of battery powder at the same time.

Description

Technical Field

[0001] This invention relates to the field of waste lithium battery recycling technology, specifically to a method for the comprehensive recycling of waste lithium battery powder and its application. Background Technology

[0002] New energy vehicles have been on the market for over a decade, and their market share expanded rapidly after 2015, leading to a continuous increase in the scale of retired lithium batteries. Generally, retired lithium batteries have two main uses: first, batteries with 70%-80% of their initial capacity can be reused in energy storage and other fields as energy carriers, thus maximizing their remaining value; second, they are dismantled and then comprehensively recycled using a series of physical and chemical methods to extract metals such as nickel, cobalt, manganese, and lithium. The metal content in spent lithium batteries is far higher than that in mines, and recycling spent lithium batteries can greatly alleviate the shortage of nickel, cobalt, and lithium resources in China, and is also an effective way to protect the ecological environment.

[0003] The main recycling method for waste ternary lithium battery powder / electrode powder is leaching with acid. However, acid leaching alone results in low leaching rates for nickel, cobalt, and manganese. Reducing agents such as hydrogen peroxide, sodium sulfite, and sodium thiosulfate are usually added to improve the leaching rate, which increases production costs. The main recycling method for waste lithium iron phosphate battery powder / electrode powder is leaching with acid and oxidants. Oxidants often include hydrogen peroxide and ferric salts. Leaching with hydrogen peroxide does not introduce additional impurities, but it is costly. Using ferric salt cyclic leaching presents challenges in production operations due to the formation of ferric hydroxide colloids during the reaction, making separation of the leachate and leaching residue difficult. Furthermore, phosphorus tends to accumulate in the leachate after the ferric salts are recycled, making subsequent lithium solution impurity removal difficult and costly. Additionally, the synthesis process of iron phosphate and lithium carbonate generates large amounts of mother liquor and wash water. The mother liquor typically contains trace amounts of lithium and phosphorus, and the wash water typically contains trace amounts of iron and phosphorus. Direct treatment of these materials results in a waste of lithium, iron, and phosphorus elements and incurs high processing costs. Summary of the Invention

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a method for comprehensive recycling of waste lithium battery powder and its application, which solves the problems of high production cost, low recovery rate of valuable metals, difficult operation, and difficulty in removing impurities from lithium liquid during the wet recycling of battery powder, and can simultaneously recycle multiple types of battery powder.

[0005] According to a first aspect of the present invention, a method for comprehensive recycling of waste lithium battery powder is provided, comprising the following steps: S1: Mix the first battery powder with the first acid solution to carry out an acid dissolution reaction, and after solid-liquid separation, obtain the first solid residue and the reaction solution; S2: The second battery powder is mixed with the reaction solution to carry out a redox reaction, and after solid-liquid separation, a second solid residue and a first lithium liquid are obtained. S3: Mix the third battery powder with the first lithium liquid and carry out a two-stage redox reaction. After solid-liquid separation, the third solid residue and the second lithium liquid are obtained. Wherein, the first battery powder is selected from at least one of lithium iron phosphate battery powder or lithium manganese iron phosphate battery powder; the second battery powder and the third battery powder are independently selected from at least one of ternary battery powder, lithium cobalt oxide battery powder or lithium manganese oxide battery powder. The molar amount of hydrogen ions in the first acid solution is 4 to 8 times the molar amount of lithium in the first battery powder; The total lithium molar amount of the second battery powder is 0.1 to 0.5 times the total lithium molar amount of the first battery powder; The total lithium molar amount of the third battery powder is 1 to 2 times the ferrous ion molar amount in the first lithium liquid.

[0006] This invention eliminates the need for additional oxidants or reducing agents. It utilizes the ferrous ions dissolved from lithium iron phosphate or lithium manganese iron phosphate battery powder / electrode powder to directly react with nickel, cobalt, and manganese in ternary lithium (such as lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide), lithium cobalt oxide, or lithium manganese oxide battery powder / electrode powder to generate easily soluble divalent nickel cobalt manganese. This avoids the introduction of impurity elements. Furthermore, by controlling the reaction ratio between oxidizing and reducing battery powder, all valuable metals in the battery powder are extracted at different reaction stages.

[0007] In some embodiments, the first acid solution is at least one of sulfuric acid, nitric acid, hydrochloric acid, or phosphoric acid.

[0008] The following reactions mainly occur in step S1, and the main component of the first solid slag is graphite: LiFePO4+ 3H + = Li + + Fe 2+ + H3PO4; LiFe x Mn (1-x) PO4+ 3H + = Li + +xFe 2+ + (1-x)Mn 2+ +H3PO4, where 0 < x < 1 In step S2, the following main reaction occurs, where M is nickel, cobalt, or manganese. During this reaction, Fe... 2+ The molar amount of Fe is 2-10 times that of LiMO2, therefore, after the reaction is complete, there will still be unreacted Fe. 2+Proceeding to the next step (two-stage redox reaction); the corresponding LiMO2 is basically completely reacted, and the main components of the second solid slag are iron phosphate and graphite, while the main component of the first lithium liquid is Fe. 2+ Li + M 2+ H + : Fe 2+ + PO4 3- + 4H + + LiMO2= Li + + M 2+ + FePO4↓ + 2H2O In step S3, the following main reaction occurs, where M is nickel, cobalt, or manganese. During this reaction, the molar amount of LiMO2 is Fe. 2+ The amount is 1 to 2 times that of Fe, therefore, after the reaction is complete, there is still unreacted LiMO2, which can be used to return to step S2 for a redox reaction; the corresponding Fe 2+ The reaction was basically complete. The main components of the third solid slag were iron phosphate, graphite, and some LiMO2, while the main component of the second lithium liquid was Li. + M 2+ : Fe 2+ + PO4 3- + 4H + + LiMO2= Li + + M 2+ + FePO4↓ + 2H2O In some embodiments, the method for comprehensive recycling of waste lithium battery powder further includes the following steps: S4: The first impurity removal agent is mixed with the second lithium liquid to carry out the first impurity removal reaction. After solid-liquid separation, the fourth solid residue and the third lithium liquid are obtained. S5: The first precipitant is mixed with the third lithium liquid to carry out the first precipitation reaction, and after solid-liquid separation, the first lithium salt and the first mother liquor are obtained. S6: The second precipitant is mixed with the first mother liquor to carry out a second precipitation reaction. After solid-liquid separation, the second lithium salt and the second mother liquor are obtained. After evaporation of the second mother liquor, solid-liquid separation is carried out again to obtain crystalline salt and the third mother liquor. Wherein, the first impurity removal agent is at least one of sodium carbonate, potassium carbonate, lithium carbonate, calcium carbonate, sodium hydroxide, potassium hydroxide, lithium hydroxide, or calcium hydroxide; And / or, the first precipitant is at least one of sodium carbonate or potassium carbonate, and the molar amount of the first precipitant is 0.5 to 0.55 times the molar amount of lithium ions in the third lithium solution; And / or, the second precipitant is at least one of sodium phosphate or potassium phosphate, and the molar amount of the second precipitant is 0.3 to 0.4 times the molar amount of lithium ions in the first mother liquor. The second precipitation reaction can deeply precipitate lithium, and the lithium concentration in the resulting second mother liquor is below 0.3 g / L.

[0009] The following reaction mainly occurs in step S4, where M is nickel, cobalt, or manganese: M 2+ + CO3 2- =MCO3 or M 2+ + 2OH - = M(OH)2 The following reactions mainly occur in step S5: 2Li + + CO3 2- = Li2CO3 In some embodiments, the order of addition in step S5 is as follows: the third lithium liquid is added to the first precipitant. Adding the third lithium liquid to the first precipitant can reduce the lattice entrainment of impurities in the precipitate.

[0010] The following reactions mainly occur in step S6: 3Li + + PO4 3- = Li3PO4 In some embodiments, the order of addition in step S6 is as follows: the second precipitant is added to the first mother liquor.

[0011] In some embodiments, the evaporation in step S6 is carried out using a single-effect evaporator, a double-effect evaporator, a triple-effect evaporator, or an MVR evaporator. The main component of the third mother liquor is Na3PO4 or K3PO4; the crystalline salt mainly contains at least one of NaCl, NaNO3, Na2SO4, KCl, KNO3, K2SO4, CaCl2, Ca(NO3)2, and CaSO4.

[0012] In some embodiments, the method for comprehensive recycling of waste lithium battery powder further includes the following steps: S7: The second acid solution is mixed with the second solid slag in step S2 to carry out an acid dissolution reaction. After solid-liquid separation, iron phosphate solution and graphite are obtained. S8: Add ferric phosphate dihydrate seed crystals to the ferric phosphate solution, heat and react, and then perform solid-liquid separation again to obtain ferric phosphate dihydrate and the fourth mother liquor. The second acid solution is at least one of sulfuric acid, nitric acid, hydrochloric acid, or phosphoric acid, and the hydrogen ion concentration of the second acid solution is 3-5 mol / L; the molar amount of hydrogen ions in the second acid solution is 0.9-2.4 times the molar amount of total iron in the second solid slag. And / or, the amount of the ferric phosphate dihydrate seed crystals added is 5% to 10% of the total molar amount of iron in the ferric phosphate solution.

[0013] In some embodiments, the method for comprehensive recycling of waste lithium battery powder further includes the following steps: S9: The iron phosphate dihydrate is washed with water, dried and calcined in sequence to obtain battery-grade iron phosphate; The liquid-to-solid ratio of the wash water used for the washing process to the ferric phosphate dihydrate is (5~12)m. 3 1t; The roasting temperature is 550~850℃, and the roasting time is 2~5h.

[0014] The following reactions mainly occur in step S7: FePO4+ H + = Fe 3+ + HPO4 2- In some embodiments, step S8, before adding the ferrous phosphate seed crystals dihydrate, further includes: mixing the ferrous solution with the ferrous phosphate solution, and adding hydrogen peroxide to the resulting mixture to carry out an oxidation reaction; the molar amount of the hydrogen peroxide is preferably 1 to 1.5 times the molar amount of ferrous ions in the mixture.

[0015] In some preferred embodiments, the ferrous solution is obtained by: After dissolving crude ferrous sulfate heptahydrate, a second impurity removal agent is added to carry out a second impurity removal reaction. After solid-liquid separation, the ferrous sulfate solution is obtained.

[0016] In some preferred embodiments, the solid-liquid ratio of the crude ferrous sulfate heptahydrate to the solution used for dissolution is 1t:(1.5~3)m. 3 The preparation solution can be made with pure water; And / or, the second impurity remover is a phosphate-containing solution, wherein the molar amount of phosphate in the second impurity remover is 0.4% to 1% of the molar amount of ferrous ions in the crude ferrous sulfate heptahydrate; And / or, the temperature of the second impurity removal reaction is 30~50℃, and the reaction time is 10~30min.

[0017] In some preferred embodiments, the third mother liquor in step S6 is used as a second impurity remover to carry out the second impurity removal reaction.

[0018] The crude ferrous sulfate heptahydrate used in this invention is a byproduct of the sulfuric acid process for producing titanium dioxide. Its main component is ferrous sulfate, and the metal elements with higher content include iron (18%~19%), titanium (0.1%~0.15%), manganese (0.05%~0.08%), and magnesium (0.2%~0.3%).

[0019] The above process mainly involves the following reactions: 2Fe 2+ + H2O2 + 2H + = 2Fe 3+ + 2H2O In some embodiments, the temperature of the redox reaction in step S2 is 25~80°C, the reaction time is 30~240 min, and the pH at the reaction endpoint is 0~2. And / or, the temperature of the two-stage redox reaction in step S3 is 25~80℃, the reaction time is 30~480min, and the pH at the reaction endpoint is 1.5~5.5.

[0020] In some embodiments, the temperature of the first impurity removal reaction in step S4 is 50~80°C, the reaction time is 30~240 min, and the final pH of the reaction is 7~11; And / or, the temperature of the first precipitation reaction in step S5 is 80~100℃, and the reaction time is 30~240min; And / or, the temperature of the second precipitation reaction in step S6 is 70~90℃, and the reaction time is 30~240min.

[0021] In some embodiments, the acid dissolution reaction in step S7 is carried out at a temperature of 25-50°C for a reaction time of 30-240 min. And / or, the heating reaction in step S8 is carried out at a temperature of 90~98°C for a reaction time of 4~12h.

[0022] In some embodiments, the third solid residue in step S3 is recycled as the second battery powder in step S2; And / or, the fourth mother liquor in step S8 is recycled for combined treatment with the second acid liquor in step S7; And / or, the fourth mother liquor in step S8 is reused as the first acid solution in step S1.

[0023] It is understandable that the solid residue mentioned in step S3 can also be used for combined processing with the third battery powder in subsequent production processes.

[0024] In some embodiments, the wash water after the water washing in step S9 is used to dissolve crude ferrous sulfate heptahydrate.

[0025] This invention reuses the mother liquor and wash water generated in each reaction process in multiple stages, so that all valuable elements in the whole process are recovered in the form of products, realizing green, pollution-free and efficient recycling of waste lithium batteries.

[0026] According to a second aspect of the present invention, the application of the method described in the first aspect of the present invention in the preparation of lithium battery cathode materials is proposed.

[0027] According to one embodiment of the present invention, at least the following beneficial effects are achieved: This invention enables low-cost comprehensive recovery of lithium, nickel, cobalt, manganese, graphite, phosphorus, and iron from one or more types of battery powders, including ternary lithium battery powder, lithium cobalt oxide battery powder, lithium manganese oxide battery powder, lithium iron phosphate battery powder, and lithium manganese iron phosphate battery powder. The resulting products include nickel cobalt manganese carbonate / nickel cobalt manganese hydroxide, graphite, lithium carbonate, and iron phosphate. Utilizing the inherent reducing properties of lithium iron phosphate and lithium manganese iron phosphate battery powders, and the inherent oxidizing properties of ternary lithium battery powder, lithium cobalt oxide battery powder, and lithium manganese oxide battery powder, this invention eliminates the need for additional oxidants, reducing agents, or catalysts, avoiding the introduction of impurities and achieving green, pollution-free, and highly efficient recycling of waste lithium batteries. Attached Figure Description

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a process flow diagram of Embodiment 3 of the present invention. Detailed Implementation

[0029] The following will describe the concept and technical effects of the present invention clearly and completely with reference to the embodiments, so as to fully understand the purpose, features and effects of the present invention, but the present invention is not limited to the scope of the embodiments described.

[0030] Unless otherwise specified, the experimental methods in the following examples were performed according to conventional methods and conditions. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following examples can be obtained from conventional commercial sources or by existing known methods. Specifically, the lithium iron phosphate electrode powder and lithium manganese iron phosphate electrode powder are positive electrode powders obtained from waste lithium iron phosphate and lithium manganese iron phosphate batteries recycled by Yichang Bangpu Recycling Technology Co., Ltd., after discharge, disassembly, positive electrode crushing, pulverization, and sieving. The lithium iron phosphate battery powder is battery powder obtained from lithium iron phosphate battery packs recycled by Yichang Bangpu Recycling, after discharge, disassembly, crushing, and sieving. The ternary electrode powder is positive electrode powder obtained from waste ternary lithium batteries recycled by Hunan Bangpu Recycling Technology Co., Ltd., after discharge, disassembly, positive electrode crushing, pulverization, and sieving. The lithium cobalt oxide electrode powder is purchased from waste materials from the production process of Xiamen Tungsten Industry. Ferrous sulfate heptahydrate is a by-product from a titanium dioxide factory.

[0031] Example 1 This embodiment provides a method for the comprehensive recycling of waste lithium battery powder, including the following steps: (1) Weigh 100g of waste lithium iron phosphate electrode powder (containing 4.01% lithium, 32.45% iron, and 18.40% phosphorus), add 62.3ml of concentrated sulfuric acid to 400ml of pure water to prepare 2.48mol / L dilute sulfuric acid (the molar amount of hydrogen ions is 4 times the molar amount of total lithium in the lithium iron phosphate electrode powder), add 100g of waste lithium iron phosphate electrode powder to the dilute sulfuric acid, control the reaction temperature at 50℃, and react for 2h; (2) Weigh 17.4g of waste ternary electrode powder (containing 4.56% lithium, 25.1% nickel, 4.01% cobalt, and 8.43% manganese, with the lithium molar amount being 0.2 times the total lithium molar amount in the lithium iron phosphate electrode powder) and add it to the above reaction slurry. Control the reaction temperature at 60℃, stir the reaction for 2.5h, and the final pH is 0.52. Filter the mixture. The filter residue is iron phosphate and graphite, with a mass of 24.24g. The filtrate is the first lithium solution, with a volume of 455.1mL, containing nickel, cobalt, manganese, lithium, ferrous iron, phosphorus and other ions. (3) Weigh 104.8g of waste ternary electrode powder (containing 4.56% lithium, 25.1% nickel, 4.01% cobalt, and 8.43% manganese, with the molar amount of lithium being the unreacted Fe in step (2)). 2+ Add 1.5 times the molar amount) to the first lithium solution, control the reaction temperature at 65℃, stir and react for 4 hours, filter, the filter residue is unreacted ternary electrode powder and ferric phosphate slag (ferric phosphate, graphite), with a mass of 148.70g, the filtrate is the second lithium solution, with a volume of 350.96mL, containing nickel, cobalt, manganese, lithium ions, etc. (4) Add sodium hydroxide solution to the second lithium solution to adjust the pH to 10, filter, the filter residue is nickel cobalt manganese hydroxide with a mass of 208.7g, the filtrate is the third lithium solution with a volume of 318.56mL and a lithium content of 24.56g / L; (5) Add 29.4g of solid sodium carbonate to 105mL of pure water to prepare a 280g / L sodium carbonate solution. Add the third lithium solution from step (4) to the sodium carbonate solution, wherein the molar amount of sodium carbonate is 0.55 times the molar amount of lithium in the third lithium solution. Control the reaction temperature at 85℃, stir the reaction for 2.5h, filter, and the filter residue is lithium carbonate product with a mass of 51.00g and a water content of 30%; the filtrate is the first mother liquor with a volume of 279mL. (6) Add 20.72g of solid sodium phosphate to the first mother liquor, control the reaction temperature at 80℃, stir the reaction for 1h, filter, the filter residue is lithium phosphate with a mass of 6.98g and a water content of 30%; the filtrate is the second mother liquor with a volume of 284mL. (7) The second mother liquor was evaporated and concentrated to finally obtain 64.16 g of sodium sulfate decahydrate; (8) Add 6.1 mL of concentrated sulfuric acid to 65 mL of pure water to prepare 1.58 mol / L dilute sulfuric acid. Add 24.24 g of ferric phosphate obtained in step (2), stir and react for 1 h to obtain 78 mL of ferric phosphate solution. (9) Add 1.26g of iron phosphate dihydrate seed crystals to the iron phosphate solution, stir and react at 95°C for 6h, and then filter to obtain 65mL of the fourth mother liquor and 30.32g of iron phosphate dihydrate. Place the iron phosphate dihydrate in an oven and dry it at 100°C, and then place it in a muffle furnace and calcine at 700°C for 3h to obtain 17.14g of battery-grade iron phosphate product.

[0032] In this embodiment, the yield is calculated by the metal content in the raw materials and the metal content in the recovered finished products / by-products, and the overall lithium yield is calculated by reverse calculation based on the metal loss during the impurity removal process. The overall yields are 96.97%, 99.99%, 97.93%, and 97.93%, respectively.

[0033] Example 2 This embodiment provides a method for the comprehensive recycling of waste lithium battery powder, including the following steps: (1) Weigh 50g of lithium iron phosphate electrode powder (containing 4.01% lithium, 32.45% iron, and 18.40% phosphorus) and 50g of lithium manganese iron phosphate electrode powder (containing 4.05% lithium, 12.89% iron, and 20.23% manganese). Add 44ml of concentrated sulfuric acid to 400ml of pure water to prepare 1.82mol / L dilute sulfuric acid (the molar amount of hydrogen ions is 4 times the molar amount of total lithium in the lithium iron phosphate electrode powder and lithium manganese iron phosphate electrode powder). Add 50g of lithium iron phosphate electrode powder and 50g of lithium manganese iron phosphate electrode powder to the dilute sulfuric acid. Control the reaction temperature at 40℃ and react for 2h. (2) Weigh 30.7g of waste ternary electrode powder (containing 4.56% lithium, 25.1% nickel, 4.01% cobalt, and 8.43% manganese, with the lithium molar amount being 0.5 times the total lithium molar amount in lithium iron phosphate electrode powder and lithium manganese iron phosphate electrode powder) and add it to the above reaction slurry. Control the reaction temperature at 30℃, stir the reaction for 3h, and the final pH of the reaction is 0.86. Filter the mixture. The filter residue is iron phosphate and graphite, with a mass of 42.79g. The filtrate is the first lithium solution, with a volume of 431.2mL, containing nickel, cobalt, manganese, lithium, ferrous iron, phosphorus and other ions. (3) Weigh 61.5g of waste ternary electrode powder (the molar amount of lithium is the Fe that was not completely reacted in step (2)). 2+ Add twice the molar amount of the first lithium solution, control the reaction temperature at 50℃, stir and react for 3 hours, filter, the filter residue is unreacted ternary electrode powder and ferric phosphate slag (ferric phosphate, graphite), with a mass of 87.6g, the filtrate is the second lithium solution, with a volume of 369.9mL, containing nickel, cobalt, manganese, lithium ions, etc. (4) Add sodium hydroxide solution to the second lithium solution to adjust the pH to 10.5, filter, the filter residue is nickel cobalt manganese hydroxide with a mass of 147.4g, the filtrate is the third lithium solution with a volume of 322.75mL and a lithium content of 20.83g / L; (5) Add 56g of solid sodium carbonate to 200mL of pure water to prepare a 280g / L sodium carbonate solution. Add the third lithium solution from step (4) to the sodium carbonate solution, wherein the molar amount of sodium carbonate is 0.55 times the molar amount of lithium in the third lithium solution. Control the reaction temperature at 90℃, stir the reaction for 2.5h, filter, and the filter residue is lithium carbonate product with a mass of 30.00g and a water content of 30%; the filtrate is the first mother liquor with a volume of 500.38mL. (6) Add 19.92g of solid sodium phosphate to the first mother liquor, control the reaction temperature at 80℃, stir the reaction for 1h, filter, the filter residue is lithium phosphate with a mass of 7.11g and a water content of 30%; the filtrate is the second mother liquor with a volume of 459.58mL. (7) The second mother liquor was evaporated and concentrated to finally obtain 73.48 g of sodium sulfate decahydrate and 25.00 mL of the third mother liquor; (8) Add 10.78 mL of concentrated sulfuric acid to 120 mL of pure water to prepare 1.51 mol / L dilute sulfuric acid. Add 42.79 g of ferric phosphate obtained in (2) and stir for 1 h to obtain 143.61 mL of ferric phosphate solution. (9) Add 2.22g of ferric phosphate dihydrate seed crystals to the ferric phosphate solution, stir and react at 95℃ for 6h, and then filter to obtain 120mL of the fourth mother liquor and 53.43g of ferric phosphate dihydrate. Wash the ferric phosphate dihydrate with 534.3ml of pure water, and then filter to obtain 534.3ml of wash water and 53.43g of ferric phosphate dihydrate. Place the ferric phosphate dihydrate in an oven and dry at 100℃, and then place it in a muffle furnace and calcine at 700℃ for 3h to obtain 30.20g of battery-grade ferric phosphate product.

[0034] In this embodiment, the yield is calculated by the metal content in the raw materials and the metal content in the recovered finished products / by-products, and the overall lithium yield is calculated by reverse calculation based on the metal loss during the impurity removal process. The overall yields are 96.76%, 99.99%, 91.83%, and 91.83%.

[0035] Example 3 This embodiment provides a method for the comprehensive recycling of waste lithium battery powder, such as... Figure 1 As shown, it includes the following steps: (1) Weigh 50g of lithium iron phosphate battery powder (containing 2.70% lithium and 22% iron) and 50g of lithium manganese iron phosphate electrode powder (containing 4.05% lithium, 12.89% iron and 20.23% manganese). Take 120mL of the fourth mother liquor in step (9) of Example 2 and add 32.31mL of concentrated sulfuric acid to the fourth mother liquor to prepare 5.11mol / L dilute sulfuric acid (the molar amount of hydrogen ions is 5 times the molar amount of total lithium in lithium iron phosphate battery powder and lithium manganese iron phosphate electrode powder). Add 50g of lithium iron phosphate battery powder and 50g of lithium manganese iron phosphate electrode powder to dilute sulfuric acid, control the reaction temperature at 30℃, and react for 2h. After the reaction, filter to obtain 41.25g of graphite. The filtrate is the reaction liquid with a volume of 152.31mL, containing nickel, cobalt, manganese, lithium, ferrous iron, phosphorus and other ions. (2) Weigh the filter residue from step (3) in Example 2. The filter residue contains 10.14g of unreacted waste ternary electrode powder (natural basis, 30% water content, 4.56% lithium, 25.1% nickel, 4.01% cobalt, and 8.43% manganese on a dry basis) and ferric phosphate slag (iron phosphate and graphite). Add 4.08g of lithium cobalt oxide electrode powder (lithium cobalt oxide electrode powder contains 5.07% lithium and 65.33% cobalt, and the total lithium molar amount of the waste ternary electrode powder and lithium cobalt oxide electrode powder is 0.3 times the total lithium molar amount of the lithium iron phosphate battery powder and the lithium manganese iron phosphate electrode powder) to the above reaction solution. Control the reaction temperature at 30°C, stir the reaction for 3 hours, and the final pH of the reaction is 0.66. Filter the solution. The filter residue is iron phosphate and graphite with a mass of 19.75g. The filtrate is the first lithium solution with a volume of 146.39mL, containing nickel, cobalt, manganese, lithium, ferrous iron, phosphorus and other ions. (3) Weigh the filter residue from step (3) of Example 2. The filter residue contains 37.84g of unreacted waste ternary electrode powder (natural basis, 30% water content, dry basis content of 4.56% lithium, 25.1% nickel, 4.01% cobalt, and 8.43% manganese) and ferrophosphate slag (ferric phosphate and graphite), and 15.22g of lithium cobalt oxide electrode powder (lithium cobalt oxide electrode powder contains 5.07% lithium and 65.33% cobalt; the total molar amount of lithium in the waste ternary electrode powder and lithium cobalt oxide electrode powder is the amount of Fe unreacted in step (2). 2+ Add 1.6 times the molar amount) to the first lithium solution, control the reaction temperature at 35℃, stir and react for 3 hours, filter, the filter residue is unreacted ternary electrode powder and lithium cobalt oxide electrode powder, with a water content of 30% and a mass of 69.39g, the filtrate is the second lithium solution, with a volume of 125.57mL, containing nickel, cobalt, manganese, lithium ions, etc. (4) Add sodium carbonate to the second lithium solution to adjust the pH to 10.5, filter, the filter residue is nickel cobalt manganese carbonate with a mass of 56.06g and a water content of 35%, the filtrate is the third lithium solution with a volume of 105.95mL and a lithium content of 20.64g / L; (5) Add 16.8g of solid sodium carbonate to 60mL of pure water to prepare a 280g / L sodium carbonate solution. Add the third lithium solution from step (4) to the sodium carbonate solution, wherein the molar amount of sodium carbonate is 0.5 times the molar amount of lithium in the third lithium solution. Control the reaction temperature at 90℃, stir the reaction for 2h, filter, and the filter residue is lithium carbonate product with a mass of 33.08g and a water content of 30%; the filtrate is the first mother liquor with a volume of 180.89mL. (6) Add 5.65g of solid sodium phosphate to the first mother liquor. The molar amount of sodium phosphate added is 0.38 times the molar amount of lithium in the third lithium solution. Control the reaction temperature at 90℃, stir the reaction for 0.5h, filter, the filter residue is lithium phosphate product with a mass of 5.21g and a water content of 30%, and the filtrate is the second mother liquor with a volume of 364.24mL. (7) The second mother liquor was evaporated and concentrated to obtain 75.28 g of sodium sulfate decahydrate; (8) Add 1 mL of concentrated sulfuric acid to 11 mL of pure water to prepare dilute sulfuric acid with a concentration of 1.53 mol / L. Take 51.41 mL of the fourth mother liquor in step (9) of Example 2, add the prepared dilute sulfuric acid and 19.75 g of ferric phosphate obtained in step (2), stir and react for 1 h to obtain 63.41 mL of ferric phosphate solution. (9) Take 100 ml of the washing water obtained in step (9) of Example 2, add 60 g of ferrous sulfate heptahydrate (containing 18% iron, 0.1% titanium, 0.05% manganese and 0.2% magnesium), stir until the ferrous sulfate heptahydrate is completely dissolved, add 12 mL of the third mother liquor in step (7) of Example 2, stir until the reaction is complete, and filter to obtain 139.19 ml of ferrous liquid after titanium removal; (10) Mix the ferric phosphate solution with the titanium-removed ferrous solution and add 16.71 ml of hydrogen peroxide (mass concentration 27.5%) to react; (11) Add 3.25g of iron phosphate dihydrate seed crystals to the above mixed solution, stir and react at 95°C for 6h, and then filter to obtain 219.3mL of the fourth mother liquor and 77.41g of iron phosphate dihydrate. Wash the iron phosphate dihydrate with 774.1ml of pure water, and then filter to obtain 774.1ml of wash water and 75.32g of iron phosphate dihydrate. Dry the iron phosphate dihydrate in an oven at 100°C, and then calcine it in a muffle furnace at 700°C for 3h to obtain 42.18g of battery-grade iron phosphate product.

[0036] In this embodiment, the overall lithium yield was 98.21%, the overall nickel-cobalt-manganese yield was 99.99%, the overall iron yield was 94.33%, and the overall phosphorus yield was 94.33%.

[0037] Comparative Example 1 (1) Weigh 100g of waste lithium iron phosphate electrode powder (containing 4.01% lithium, 32.45% iron, and 18.40% phosphorus), add 62.3ml of concentrated sulfuric acid to 400ml of pure water to prepare 2.48mol / L dilute sulfuric acid (the molar amount of hydrogen ions is 4 times the molar amount of total lithium in the lithium iron phosphate electrode powder), add 100g of waste lithium iron phosphate electrode powder to the dilute sulfuric acid, control the reaction temperature at 50℃, and react for 2h; (2) Weigh 121.89g of waste ternary electrode powder (containing 4.56% lithium, 25.1% nickel, 4.01% cobalt, and 8.43% manganese, with the lithium molar amount being 1.4 times that in lithium iron phosphate electrode powder) and add it to the above reaction slurry. Control the reaction temperature at 60℃, stir and react for 2.5h, filter, and the filter residue is a mixture of iron phosphate and unreacted waste ternary electrode powder with a mass of 190.86g. The filtrate is the first lithium solution with a volume of 455.1mL, containing nickel, cobalt, manganese, lithium, ferrous iron, phosphorus and other ions. (3) Add 39.09 mL of concentrated sulfuric acid to 350 mL of pure water to prepare 1.61 mol / L dilute sulfuric acid. Add the mixture of 190.86 mol / L iron phosphate obtained in step (2) and unreacted waste ternary electrode powder. Stir and react for 1 h to obtain 446.35 mL of acid solution containing nickel, cobalt, manganese, lithium, iron, phosphorus and other ions. (4) Add 6.30g of ferric phosphate dihydrate seed crystals to the above acid solution, stir and react at 95℃ for 6h, and then filter to obtain 219.3mL of the fourth mother liquor and 150.60g of ferric phosphate dihydrate. Wash the ferric phosphate dihydrate with 1506mL of pure water, and then filter to obtain 1506mL of wash water and 150.60g of ferric phosphate dihydrate. Place the ferric phosphate dihydrate in an oven and dry at 100℃, and then place it in a muffle furnace and calcine at 700℃ for 3h to obtain 85.12g of ferric phosphate product.

[0038] Due to an excess of waste ternary electrode powder during a redox process, some of the waste ternary electrode powder did not react completely, resulting in a large amount of nickel, cobalt, and manganese metal ions appearing in the acid solution. During the synthesis of iron phosphate, nickel, cobalt, and manganese all precipitated to varying degrees, resulting in the iron phosphate product containing 0.11% cobalt and 0.21% manganese, exceeding the requirements of Mn≤0.1% and Co≤0.005% in "HG / T4701-2021 Iron Phosphate for Batteries". Therefore, the iron phosphate product is unqualified.

[0039] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for comprehensive recycling of waste lithium battery powder, characterized in that, Includes the following steps: S1: Mix the first battery powder with the first acid solution to carry out an acid dissolution reaction, and after solid-liquid separation, obtain the first solid residue and the reaction solution; S2: The second battery powder is mixed with the reaction solution to carry out a redox reaction, and after solid-liquid separation, a second solid residue and a first lithium liquid are obtained. S3: Mix the third battery powder with the first lithium liquid and carry out a two-stage redox reaction. After solid-liquid separation, the third solid residue and the second lithium liquid are obtained. Wherein, the first battery powder is selected from at least one of lithium iron phosphate battery powder or lithium manganese iron phosphate battery powder; the second battery powder and the third battery powder are independently selected from at least one of ternary battery powder, lithium cobalt oxide battery powder or lithium manganese oxide battery powder. The molar amount of hydrogen ions in the first acid solution is 4 to 8 times the molar amount of lithium in the first battery powder; The total lithium molar amount of the second battery powder is 0.1 to 0.5 times the total lithium molar amount of the first battery powder; The total lithium molar amount of the third battery powder is 1 to 2 times the ferrous ion molar amount in the first lithium liquid.

2. The method according to claim 1, characterized in that, It also includes the following steps: S4: The first impurity removal agent is mixed with the second lithium liquid to carry out the first impurity removal reaction. After solid-liquid separation, the fourth solid residue and the third lithium liquid are obtained. S5: The first precipitant is mixed with the third lithium liquid to carry out the first precipitation reaction, and after solid-liquid separation, the first lithium salt and the first mother liquor are obtained. S6: The second precipitant is mixed with the first mother liquor to carry out a second precipitation reaction. After solid-liquid separation, the second lithium salt and the second mother liquor are obtained. After evaporation of the second mother liquor, solid-liquid separation is carried out again to obtain crystalline salt and the third mother liquor. Wherein, the first impurity removal agent is at least one of sodium carbonate, potassium carbonate, lithium carbonate, calcium carbonate, sodium hydroxide, potassium hydroxide, lithium hydroxide, or calcium hydroxide; And / or, the first precipitant is at least one of sodium carbonate or potassium carbonate, and the molar amount of the first precipitant is 0.5 to 0.55 times the molar amount of lithium ions in the third lithium solution; And / or, the second precipitant is at least one of sodium phosphate or potassium phosphate, and the molar amount of the second precipitant is 0.3 to 0.4 times the molar amount of lithium ions in the first mother liquor.

3. The method according to claim 1, characterized in that, It also includes the following steps: S7: The second acid solution is mixed with the second solid slag in step S2 to carry out an acid dissolution reaction. After solid-liquid separation, iron phosphate solution and graphite are obtained. S8: Add ferric phosphate dihydrate seed crystals to the ferric phosphate solution, heat and react, and then perform solid-liquid separation again to obtain ferric phosphate dihydrate and the fourth mother liquor. The second acid solution is at least one of sulfuric acid, nitric acid, hydrochloric acid, or phosphoric acid, and the hydrogen ion concentration of the second acid solution is 3-5 mol / L; the molar amount of hydrogen ions in the second acid solution is 0.9-2.4 times the molar amount of total iron in the second solid slag. And / or, the amount of the ferric phosphate dihydrate seed crystals added is 5% to 10% of the total molar amount of iron in the ferric phosphate solution.

4. The method according to claim 3, characterized in that, It also includes the following steps: S9: The iron phosphate dihydrate is washed with water, dried and calcined in sequence to obtain battery-grade iron phosphate; The liquid-to-solid ratio of the wash water used for the washing process to the ferric phosphate dihydrate is (5~12)m. 3 1t; The roasting temperature is 550~850℃, and the roasting time is 2~5h.

5. The method according to claim 3, characterized in that, In step S8, before adding the ferric phosphate seed crystals dihydrate, the process further includes: mixing the ferrous solution with the ferric phosphate solution, and adding hydrogen peroxide to the resulting mixture to carry out an oxidation reaction.

6. The method according to claim 1, characterized in that, The temperature of the redox reaction in step S2 is 25~80℃, the reaction time is 30~240min, and the pH at the reaction endpoint is 0~2. And / or, the temperature of the two-stage redox reaction in step S3 is 25~80℃, the reaction time is 30~480min, and the pH at the reaction endpoint is 1.5~5.

5.

7. The method according to claim 2, characterized in that, The temperature of the first impurity removal reaction in step S4 is 50~80℃, the reaction time is 30~240min, and the pH at the reaction endpoint is 7~11; And / or, the temperature of the first precipitation reaction in step S5 is 80~100℃, and the reaction time is 30~240min; And / or, the temperature of the second precipitation reaction in step S6 is 70~90℃, and the reaction time is 30~240min.

8. The method according to claim 3, characterized in that, The acid dissolution reaction in step S7 is carried out at a temperature of 25~50℃ and for a reaction time of 30~240 min. And / or, the heating reaction in step S8 is carried out at a temperature of 90~98°C for a reaction time of 4~12h.

9. The method according to claim 3, characterized in that, The third solid residue in step S3 is recycled as the second battery powder in step S2; And / or, the fourth mother liquor in step S8 is recycled for combined treatment with the second acid liquor in step S7; And / or, the fourth mother liquor in step S8 is reused as the first acid solution in step S1.

10. The application of the method according to any one of claims 1-9 in the preparation of lithium battery cathode materials.

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