Recycling method of lithium iron phosphate waste

Abstract

The invention provides a method for recycling lithium iron phosphate waste. The method comprises the following steps: S1, preparing lithium iron phosphate mixed powder; s2, performing high-temperature activation on the lithium iron phosphate mixed powder to obtain an intermediate product; s3, carrying out acid leaching on the intermediate product, and filtering out filter residues to obtain filtrate; s4, a PH regulator is added into the filtrate to regulate the PH of the filtrate to a preset PH range, a mixed solution containing an iron-containing compound is obtained, and the iron-containing compound is obtained through precipitation after an iron source in the filtrate reacts with the PH regulator; and S5, heating the filtrate from which the iron-containing compound is filtered out, and carrying out evaporative crystallization to obtain the lithium source. According to the method, pure ferric salt and lithium salt can be effectively extracted through fine treatment steps and control conditions, and the problems of high cost, low recovery rate and excessive impurities in the prior art are solved.

Description

Technical Field

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

[0002] Due to its advantages such as high theoretical capacity, safety, low toxicity, and good cycle stability, lithium iron phosphate battery is considered an excellent cathode material and is widely used in electronic devices, large energy storage devices, electric vehicles, and hybrid electric vehicles, especially electric buses. With the continuous increase in the market demand for batteries, limited by the service life of the batteries, the number of future scrapped lithium iron phosphate batteries will be extremely large. Therefore, the recycling of lithium iron phosphate is crucial.

[0003] If the treatment method is improper, serious problems will arise. When waste lithium iron phosphate batteries are directly discarded in landfills or recycled inappropriately, toxic lithium iron phosphate organic electrolytes and metal ions will gradually transfer to the soil and groundwater, not only wasting valuable resources but also causing environmental pollution. Existing lithium iron phosphate recycling processes have disadvantages such as excessive impurities, high energy consumption, unstable recovery rate, and difficult tail liquid treatment. Therefore, it is particularly important to develop a simple and efficient recycling process. Summary of the Invention

[0004] The main object of the present invention is to provide a method for recycling lithium iron phosphate waste to solve the technical problems of high cost, low recovery rate, and excessive impurities in the recycling process of lithium iron phosphate batteries in the prior art.

[0005] To achieve the above object, according to one aspect of the present invention, a method for recycling lithium iron phosphate waste is provided, the method comprising: Step S1: preparing a lithium iron phosphate mixed powder; Step S2: performing high-temperature activation on the lithium iron phosphate mixed powder to obtain an intermediate product; Step S3: performing acid leaching on the intermediate product and filtering out the filter residue to obtain a filtrate; Step S4: adding a pH regulator to the filtrate to adjust the pH of the filtrate to a preset pH range to obtain a mixed solution including an iron-containing compound, and the iron-containing compound is precipitated by the reaction of the iron source in the filtrate with the pH regulator; Step S5: heating the filtrate after filtering out the iron-containing compound and performing evaporation crystallization to obtain a lithium source.

[0006] Further, performing high-temperature activation on the lithium iron phosphate mixed powder includes: placing the lithium iron phosphate mixed powder in an atmosphere muffle furnace, heating it to a temperature target value at a constant heating rate in an air atmosphere, keeping it at a constant temperature for 2 - 6 h, and then naturally cooling to obtain an intermediate product.

[0007] Further, the heating rate is 2 - 10 °C / min, and / or, the temperature target value is 500 - 700 °C.

[0008] Further, after acid leaching the intermediate product and filtering out the filter residue, a filtrate is obtained, including: adding a material comprising the intermediate product and an acidic solvent into a container; placing the container in a microwave reactor and reacting for a preset duration at a preset temperature, and filtering out the filter residue from the reaction product to obtain the filtrate.

[0009] Further, in the step of adding the material comprising the intermediate product and the acidic solvent into the container, by mass parts, the ratio of the intermediate product to the acidic solvent is (1:13) - (1:15), preferably 1:14.

[0010] Further, the preset temperature is 70°C - 80°C, preferably 75°C, and / or the preset duration is 3 min - 7 min, preferably 5 min.

[0011] Further, the acidic solvent is hydrogen chloride.

[0012] Further, the pH regulator is ammonia water.

[0013] Further, the preset pH range is 1.5 - 2.5, preferably pH = 2.

[0014] Further, preparing the lithium iron phosphate mixed powder includes: soaking the electrode sheet waste in a lithium iron phosphate battery in a sodium hydroxide solution, removing the aluminum foil after stirring, then filtering, drying the obtained solid in an oven at 80°C for 10 - 14 h, grinding and sieving to obtain the lithium iron phosphate mixed powder.

[0015] Applying the technical solution of the present invention, by treating the waste to prepare the lithium iron phosphate mixed powder, the recycling of the waste effectively improves the resource utilization efficiency. Then, the mixed powder is activated under high-temperature conditions to form an intermediate product, and then treated with an acidic solution to filter out solid impurities to obtain a filtrate. Filtering out solid impurities helps to improve the product purity. In addition, by adding a pH regulator to control the acidity and alkalinity of the filtrate, a mixed solution containing iron compounds is generated. The filtrate after filtering out the iron compounds is heated to evaporate and crystallize to obtain a lithium source. The above method can effectively extract pure iron salts and lithium salts through fine processing steps and controlled conditions, solving the problems of high cost, low recovery rate, and excessive impurities in the existing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0017] Figure 1 Shows a flowchart of an embodiment of a method for recycling lithium iron phosphate waste according to the present invention;

[0018] Figure 2 The process flow diagram of an embodiment of a method for recycling lithium iron phosphate waste according to the present invention is shown. Detailed implementation manners

[0019] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0020] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary implementation manners according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0021] It should be noted that the terms "first", "second", etc. in the description and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprise" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0022] Now, exemplary embodiments according to the present application will be described in more detail with reference to the drawings. However, these exemplary embodiments can be implemented in many different forms and should not be construed as being limited only to the embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of the present application is thorough and complete, and the concepts of these exemplary embodiments are fully conveyed to those of ordinary skill in the art. In the drawings, for clarity, the thickness of layers and regions may be exaggerated, and the same reference numerals are used to denote the same devices, and thus their descriptions will be omitted.

[0023] Combined with Figures 1 to 2 As shown, according to a specific embodiment of the present application, a method for recycling lithium iron phosphate waste is provided.

[0024] Specifically, as Figure 1As shown in the figure, the method includes: Step S1: Prepare a lithium iron phosphate mixed powder; Step S2: Perform high-temperature activation on the lithium iron phosphate mixed powder to obtain an intermediate product; Step S3: Acid-leach the intermediate product and filter out the filter residue to obtain a filtrate; Step S4: Add a pH regulator to the filtrate to adjust the pH of the filtrate to a preset pH range, obtaining a mixed solution containing an iron compound, where the iron compound is precipitated by the reaction of the iron source in the filtrate with the pH regulator; Step S5: Heat the filtrate after filtering out the iron compound, and evaporate and crystallize to obtain a lithium source.

[0025] Furthermore, the lithium iron phosphate mixed powder is prepared by treating waste materials. The reuse of waste materials effectively improves the resource utilization efficiency. Then, the mixed powder is activated under high-temperature conditions to form an intermediate product. Next, it is treated with an acidic solution to filter out solid impurities and obtain a filtrate. Filtering out solid impurities helps improve the product purity. In addition, by adding a pH regulator to control the acidity and alkalinity of the filtrate, a mixed solution containing an iron compound is generated. The filtrate after filtering out the iron compound is heated to evaporate and crystallize to obtain a lithium source. Through the above-mentioned fine processing steps and controlled conditions, the above method can effectively extract pure iron salts and lithium salts, solving the problems of high cost, low recovery rate, and excessive impurities in the existing process.

[0026] Furthermore, performing high-temperature activation on the lithium iron phosphate mixed powder includes: placing the lithium iron phosphate mixed powder in an atmosphere muffle furnace, heating it at a constant heating rate to a temperature target value in an air atmosphere, keeping it at a constant temperature for 2 - 6 h, and then naturally cooling it to obtain an intermediate product.

[0027] Specifically, in the process of preparing the high-temperature activation product, first place the lithium iron phosphate mixed powder in an atmosphere muffle furnace to ensure treatment in an air atmosphere. By controlling the heating rate, the temperature gradually rises to the set target value. After reaching the target temperature, keep it at a constant temperature for 2 - 6 hours to allow the mixture to fully react and transform. Then, let the sample naturally cool in the furnace to obtain a reddish-brown mixture. This process aims to promote chemical reactions in the mixed powder through high-temperature treatment, enabling the generation of new substances or the change of structure, thus forming a reddish-brown mixture to provide a basis for subsequent steps.

[0028] Among them, the heating rate is 2 - 10 °C / min, and / or the temperature target value is 500 - 700 °C. Slowly heating at 2 - 10 °C / min can ensure that the lithium iron phosphate mixed powder has enough time to react when reaching the target temperature, making the reaction more complete. At the same time, the constant heating rate can help control the reaction rate, ensure the uniform progress of the reaction process, and avoid uneven or out-of-control reactions caused by too rapid temperature changes.

[0029] Further, after acid leaching the intermediate product and filtering out the filter residue, a filtrate is obtained, including: adding a material comprising the intermediate product and an acidic solvent into a container; placing the container in a microwave reactor and reacting for a preset duration at a preset temperature, and filtering out the filter residue from the reaction product to obtain the filtrate.

[0030] Specifically, during the acid leaching process, first, a material of a reddish-brown mixture and an acidic solvent hydrogen chloride is added into a container, and then the container is placed in a microwave reactor and reacted for a preset duration at a preset temperature. With microwave heating, the reaction materials will be heated and the reaction will be promoted to occur, generating new compounds. Then, the reaction mixture is subjected to a filter residue removal treatment, that is, the solid impurities are separated by filtration to obtain a clear filtrate. Using hydrochloric acid for acid leaching (microwave) instead of hydrogen peroxide can reduce costs. Using microwave for the acid leaching process shortens the reaction time and increases the acid leaching efficiency.

[0031] Among them, in the step of adding the material comprising the intermediate product and the acidic solvent into the container, by mass, the ratio of the intermediate product to the acidic solvent is (1:13) - (1:15), preferably 1:14. During the acid leaching process, the ratio of the reddish-brown mixture to the acidic solvent hydrogen chloride is (1:13) - (1:15), preferably 1:14. An appropriate ratio can ensure that the reaction materials react fully under acidic conditions and improve the reaction efficiency. The ratio of 1:14 is the preferred ratio, and through optimization, the reaction stability and product purity can be improved.

[0032] Further, the preset temperature is 70°C - 80°C, preferably 75°C, and / or the preset duration is 3 min - 7 min, preferably 5 min. The preferred selection of temperature and duration can effectively control the reaction conditions, ensure that the reaction proceeds within a suitable temperature and time range, and improve the reaction efficiency. This setting can make the reaction conditions stable and controllable, which is beneficial to the repeatability and accuracy of experimental results.

[0033] Further, the acidic solvent is hydrogen chloride. Hydrochloric acid has an economical price and a relatively low use cost, which is beneficial to reducing the experimental cost. Hydrogen chloride can provide chloride ions to accelerate the reaction rate. At the same time, hydrogen chloride is a strong acid with good solubility, which can effectively dissolve the intermediate product and promote the reaction.

[0034] Further, the pH regulator is ammonia water.

[0035] Specifically, ammonia water is added to the filtrate to adjust the pH, forming a jelly-like precipitate of iron phosphate. After filtering, washing, and drying, iron phosphate with a uniform particle size distribution is obtained. Then, the remaining filtrate is heated at a high temperature to evaporate and crystallize to obtain the corresponding lithium salt. Ammonia water can react with iron ions to form a precipitate, which is beneficial to separating iron from other impurities. At the same time, ammonia water itself is a compound with good solubility, which is convenient for uniform dispersion and pH adjustment in the reaction system.

[0036] Further, the preset pH range is 1.5 - 2.5, preferably pH = 2. Within this pH range, it is beneficial for the reaction of iron ions with ammonia water to form a precipitate, promoting the formation of lithium iron phosphate. Setting pH = 2 can effectively control the acidity and alkalinity of the reaction system, making the reaction conditions stable and facilitating subsequent filtration and separation.

[0037] Further, the preparation of the lithium iron phosphate mixed powder includes: soaking the electrode sheet waste in a lithium iron phosphate battery in a sodium hydroxide solution, removing the aluminum foil after stirring, then filtering, drying the obtained solid in an oven at 80 °C for 10 - 14 h, grinding and sieving to obtain the lithium iron phosphate mixed powder.

[0038] Specifically, in the process of preparing the lithium iron phosphate mixed powder, first soak the electrode sheet waste in the lithium iron phosphate battery in a sodium hydroxide solution, and remove the aluminum foil after stirring. Subsequently, the solid is separated by filtration, and then the solid is dried in an oven at 80 °C for 10 - 14 hours to remove moisture. Finally, the dried solid is ground and sieved to obtain the lithium iron phosphate mixed powder. By processing the electrode sheet waste in the lithium iron phosphate battery, the reuse and resource utilization of the waste are realized. The drying and grinding processes are adopted, which are beneficial to improving the uniformity and purity of the lithium iron phosphate mixed powder and optimizing the physical properties of the material.

[0039]

Example 1

[0040] 1. Preparation of the lithium iron phosphate mixed powder: Take 20 g of the electrode sheet and soak it in a 0.1 mol / L NaOH solution. After stirring for 0.5 h, the material completely falls off the aluminum foil. The aluminum foil can be directly recycled after washing. The obtained solid after filtration is dried in an oven at 80 °C for 12 h, ground and sieved to obtain the lithium iron phosphate mixed powder.

[0041] 2. Preparation of the high-temperature activated product: Put the mixed powder into an atmosphere muffle furnace, heat it to 600 °C at a constant rate of 2 °C / min in an air atmosphere, keep it at a constant temperature for 2 - 6 h, and cool it naturally to obtain a reddish-brown loose mixture.

[0042] 3. Acid leaching process: Weigh 20 g of the mixture and divide it into two sample tubes. The liquid-solid ratio is 14. Add 5 mol / L HCl respectively, put it into a microwave reactor and react at 75 °C for 5 min, filter, wash, and dry to obtain residue 2 and filtrate 2.

[0043] 4. Iron salt recovery: Add 5 mol / L ammonia water to filtrate 2 to adjust the pH = 2, and a jelly-like precipitate FePO 4 is formed. Filter, wash, and dry to obtain the FePO 4 precipitate and filtrate 3. After purification, FePO with a uniform particle size distribution is obtained4 。

[0044] 5. Lithium salt recovery: Directly heat filtrate 3 at 80 °C, and evaporate and crystallize to obtain the corresponding lithium salt.

[0045]

Example 2

[0046] 1. Take 20 g of the electrode sheet and soak it in 0.1 mol / L NaOH solution. After stirring for 0.5 h, the material completely falls off the aluminum foil. The aluminum foil can be directly recycled after cleaning. The solid obtained by filtration is dried in an oven at 80 °C for 12 h, ground and sieved to obtain the lithium iron phosphate mixed powder.

[0047] 2. Put the mixed powder into an atmosphere muffle furnace, and heat it from room temperature to 600 °C at a constant rate of 2 °C / min under an air atmosphere, keep it at a constant temperature for 2 - 6 h, and cool it naturally to obtain a reddish-brown loose mixture.

[0048] 3. Weigh 20 g of the mixture and divide it into two sample tubes with a liquid-solid ratio of 14. Add 5 mol / L HCl respectively, put it into a microwave reactor and react at 75 °C for 5 min, filter, wash and dry to obtain residue 2 and filtrate 2, and the acid leaching efficiency is 96%.

[0049] 4. Add 5 mol / L ammonia water to filtrate 2 to adjust the pH = 2, and a jelly-like precipitate FePO 4 is formed. Filter, wash and dry to obtain the FePO 4 precipitate and filtrate 3. After purification, FePO 4 with a uniform particle size distribution is obtained.

[0050] 5. Directly heat filtrate 3 at 80 °C, and evaporate and crystallize to obtain LiCl·H 2 O.

[0051]

Example 3

[0052] 1. Take 20 g of the electrode sheet and soak it in 0.1 mol / L NaOH solution. After stirring for 0.5 h, the material completely falls off the aluminum foil. The aluminum foil can be directly recycled after cleaning. The solid obtained by filtration is dried in an oven at 80 °C for 12 h, ground and sieved to obtain the lithium iron phosphate mixed powder.

[0053] 2. Weigh 20 g of the mixed powder and divide it into two sample tubes with a liquid-solid ratio of 14. Add 5 mol / L HCl respectively, put it into a microwave reactor and react at 75 °C for 5 min, filter, wash and dry to obtain residue 2 and filtrate 2, and the acid leaching efficiency is only 56%.

[0054] 3. Add 5 mol / L ammonia water to filtrate 2 to adjust the pH = 2, and a jelly-like precipitate FePO 4 is formed. Filter, wash and dry to obtain the FePO4 The precipitate and filtrate 3 are purified to obtain FePO with a uniform particle size distribution 4 .

[0055] 4. The filtrate 3 is directly heated at 80 °C, and evaporated to crystallize to obtain LiCl·H 2 O.

[0056]

Example 4

[0057] 1. Take 20 g of the electrode and soak it in 0.1 mol / L NaOH solution, stir for 0.5 h, and the material completely falls off the aluminum foil. The aluminum foil can be directly recycled after cleaning. The solid obtained by filtration is dried in an oven at 80 °C for 12 h, ground and sieved to obtain a lithium iron phosphate mixed powder.

[0058] 2. Put the mixed powder into an atmosphere muffle furnace, heat it at a constant rate of 2 °C / min to 600 °C in an air atmosphere, keep it at a constant temperature for 2 - 6 h, and cool it naturally to obtain a red-brown loose mixture.

[0059] 3. Weigh 20 g of the mixture and put it into a beaker, with a liquid-solid ratio of 14, add 5 mol / L HCl, heat and stir at 75 °C for 4 h, filter, wash and dry to obtain filter residue 2 and filtrate 2, and the acid leaching efficiency is 78%.

[0060] 4. Add 5 mol / L ammonia water to filtrate 2 to adjust the pH = 2 to form a jelly-like precipitate FePO 4 , filter, wash and dry to obtain FePO 4 precipitate and filtrate 3, which are purified to obtain FePO with a uniform particle size distribution 4 .

[0061] 5. The filtrate 3 is directly heated at 80 °C, and evaporated to crystallize to obtain LiCl·H 2 O.

[0062] In Example 2, Example 3 and Example 4, different acid leaching efficiencies are set respectively. The advantages of setting different acid leaching efficiencies are as follows:

[0063] 1. Optimize the reaction conditions: By adjusting the acid leaching efficiency, the optimal treatment conditions can be determined to improve the reaction efficiency and the purity of the product.

[0064] 2. Improve the experimental accuracy: Trying different acid leaching efficiencies can help verify the accuracy of the experimental results and ensure the reliability of the experimental data.

[0065] 3. Determine the optimal process parameters: By comparing the reaction results under different acid leaching efficiencies, the most suitable process parameters can be found to improve the stability and efficiency of the process.

[0066] 4. Resource conservation: By optimizing the acid leaching efficiency, the usage amount of reagents can be saved, costs can be reduced, and resource utilization rate can be improved.

[0067] 5. Potential exploration: Trying different acid leaching efficiencies can explore new reaction paths and possibilities, helping to discover potential optimization solutions and improvement measures.

[0068] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0069] The lithium iron phosphate mixed powder is prepared by treating the waste material. Through the reuse of the waste material, the resource utilization efficiency is improved. The mixed powder is activated under high temperature conditions to form an intermediate product, which is then treated with an acidic solution to filter out solid impurities to obtain a filtrate. Hydrochloric acid acid leaching (microwave treatment) is carried out without using hydrogen peroxide. Filtering out solid impurities helps to improve the product purity. By adding a pH regulator to control the pH value of the filtrate, a mixed solution containing iron compounds is generated. The filtrate after filtering out the iron compounds is heated for evaporation crystallization to obtain a pure lithium source. Its process flow is simple and efficient, the product has good crystallinity and high purity. At the same time, the usage amount of hydrogen peroxide is reduced, and the cost is lowered. Using microwave for the acid leaching process shortens the reaction time, increases the acid leaching efficiency, and directly drying the filtrate ensures no impurity introduction.

[0070] For the sake of description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "above" etc. can be used here to describe the spatial position relationship between a device or feature shown in the figure and other devices or features. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device described in the figure. For example, if the device in the figure is inverted, the device described as "above other devices or structures" or "over other devices or structures" will be positioned as "below other devices or structures" or "under other devices or structures" afterwards. Thus, the exemplary term "above..." can include both the orientations of "above..." and "below...". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding explanations will be made for the spatial relative descriptions used here.

[0071] In addition to the above, it should also be noted that the "one embodiment", "another embodiment", "embodiment" and the like mentioned in this specification refer to the specific features, structures or characteristics described in connection with the embodiment being included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in connection with any one embodiment, it is intended that the implementation of such feature, structure or characteristic in connection with other embodiments also falls within the scope of the present invention.

[0072] In the above embodiments, the descriptions of each embodiment have their own emphases. For the parts not detailed in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0073] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for recycling lithium iron phosphate waste, characterized in that: include: Step S1: preparing lithium iron phosphate mixed powder; Step S2: activating the lithium iron phosphate mixed powder at high temperature to obtain an intermediate product; Step S3: acid leaching the intermediate product and filtering out the residue to obtain a filtrate; Step S4: adding a pH regulator to the filtrate to adjust the pH of the filtrate to a preset pH range, thereby obtaining a mixed solution including an iron-containing compound, wherein the iron-containing compound is precipitated after the iron source in the filtrate reacts with the pH regulator; Step S5: heating the filtrate after filtering out the iron-containing compound, evaporating and crystallizing to obtain a lithium source.

2. The method for recycling lithium iron phosphate waste according to claim 1, characterized in that: The high temperature activation of the lithium iron phosphate mixed powder comprises: The lithium iron phosphate mixed powder is placed in an atmosphere muffle furnace, heated to a target temperature at a constant heating rate in an air atmosphere, kept at the constant temperature for 2-6 hours, and then naturally cooled to obtain the intermediate product.

3. The method for recycling lithium iron phosphate waste according to claim 1 or 2, characterized in that: The heating rate is 2-10°C / min, and / or the temperature target value is 500-700°C.

4. The method for recycling lithium iron phosphate waste according to claim 1, characterized in that: The intermediate product is acid-leached and then the residue is filtered out to obtain a filtrate, comprising: Adding materials including the intermediate product and an acidic solvent into a container; The container is placed in a microwave reactor to react at a preset temperature for a preset time, and the filtrate is obtained by filtering out the residue from the reaction product.

5. The method for recycling lithium iron phosphate waste according to claim 4, characterized in that: In the step of adding the material including the intermediate product and the acidic solvent into the container, the ratio of the intermediate product to the acidic solvent is (1:13) to (1:15), preferably 1:14, in parts by mass.

6. The method for recycling lithium iron phosphate waste according to claim 4 or 5, characterized in that: The preset temperature is 70°C-80°C, preferably 75°C, and / or the preset time is 3min-7min, preferably 5min.

7. The method for recycling lithium iron phosphate waste according to claim 4, characterized in that: The acidic solvent is hydrogen chloride.

8. The method for recycling lithium iron phosphate waste according to claim 1, characterized in that: The pH adjuster is ammonia water.

9. The method for recycling lithium iron phosphate waste according to claim 1, characterized in that: The preset pH range is 1.5-2.5, preferably pH=2.

10. The method for recycling lithium iron phosphate waste according to claim 1, characterized in that: The preparation of lithium iron phosphate mixed powder includes: soaking the waste pole pieces in the lithium iron phosphate battery in a sodium hydroxide solution, removing the aluminum foil after stirring, and then filtering, drying the solid obtained after filtration in an oven at 80° C. for 10-14 hours, grinding and sieving to obtain the lithium iron phosphate mixed powder.

Images