Method for preparing battery-grade iron phosphate by using high-pressure hydrolysis product of cobalt-iron alloy acid leaching solution as raw material

Abstract

The present application relates to a kind of battery grade phosphorus iron preparation method of cobalt iron alloy acid leaching solution high pressure hydrolysis product as raw material, comprising the following steps: (1) cobalt iron alloy acid leaching solution high pressure hydrolysis product powder is added in deionized water, mixed and stirred again join phosphoric acid solution, after stirring evenly, obtain yellow mixed solution, heating reaction, filtration, obtain clear solution, control solution pH value is 1.10-1.20;(2) the clear solution obtained in stirring case, join the reducing iron powder, again join H2O2, continue stirring, again filter;(3) the solution obtained after filtering in step (2) is adjusted to the pH value between 2.85-3.50, obtain white precipitate and filter, wash, dry, i.e. battery grade phosphorus iron FePO4 Product.Compared with prior art, the method has the advantages of simple process route, low preparation cost and easy to enlarge, etc.

Description

Technical Field

[0001] This invention belongs to the field of resource utilization of cobalt-iron alloy acid leaching solution and preparation technology of battery-grade iron phosphate, and relates to a method for preparing battery-grade iron phosphate using high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution as raw materials. Background Technology

[0002] Lithium iron phosphate (LiFePO4) is an excellent cathode material for lithium-ion batteries due to its high energy density, excellent cycle stability, and safety stability. Because of its structural stability, lithium iron phosphate maintains a relatively stable structure even at high temperatures, and will not cause smoke or fire even when the battery is deformed or damaged. The thermal decomposition temperature of a fully charged lithium iron phosphate material is around 700℃, while that of ternary materials is 200-300℃, making lithium iron phosphate batteries extremely safe and reliable. In recent years, the market demand for lithium iron phosphate has increased rapidly, leading to a sharp increase in the demand for battery-grade iron phosphate, the precursor of lithium iron phosphate. Traditionally, battery-grade iron phosphate is prepared by reacting iron scrap with phosphoric acid, but this method has several drawbacks: (1) the cost of iron scrap increases the cost of iron phosphate preparation; (2) the reaction of iron scrap with phosphoric acid releases a large amount of dangerous hydrogen gas. These two issues limit the large-scale production of iron phosphate. In recent years, the preparation of battery-grade iron phosphate using iron-containing waste liquid has become a hot topic in the industry. First, the iron-containing waste liquid incurs virtually no cost, allowing companies to use it as a raw material to replace sheet metal, thereby reducing the cost of sheet metal. Second, the reaction involving the iron-containing waste liquid does not involve the generation of hazardous hydrogen gas, thus ensuring the safety of the company's production.

[0003] Cobalt-iron alloys are mainly derived from cobalt-containing slag in copper smelting. These alloys contain a large amount of iron and a small amount of cobalt. After acid leaching with sulfuric acid, the small amount of cobalt is extracted through controlled reaction parameters, while the large amount of iron remains in the liquid solution, primarily as ferrous sulfate. The hydrolysis of iron ions is the most important and common reaction for precipitating and separating iron, and it is also a very complex process. The properties of the solution and the hydrolysis conditions significantly affect the hydrolysis results, leading to different hydrolysate compositions and structures. Previous research has extensively investigated the reaction mechanism of high-temperature hydrolysis products (mainly iron oxides and hydroxides) in ferrous sulfate solutions. The process of ferrous sulfate hydrolysis forming a precipitate is a high-temperature oxidative hydrolysis precipitation, and due to the low solubility of ferrous sulfate at high temperatures, the precipitation process is accompanied by a redissolution of ferrous sulfate. How to utilize the high-pressure hydrolysis products of cobalt-iron alloy acid leaching solutions to prepare battery-grade iron phosphate has become an important research topic and a current research hotspot and challenge in the industry.

[0004] With the rapid development of my country's new energy industry, battery manufacturers have had to comprehensively consider factors such as cost, ease of process control, and performance, making the supply of battery-grade iron phosphate raw materials and environmental protection increasingly prominent issues. Against this backdrop, seeking alternative raw materials and the resource utilization of iron-containing waste liquids / solids has become a focus of industry attention. For example, CN202011436682.2 provides a method for preparing battery-grade flake iron phosphate using cobalt-iron leaching solution. However, no literature reports have yet been found on the preparation of battery-grade iron phosphate using high-pressure hydrolysis products of cobalt-iron alloy acid leaching solutions. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing battery-grade iron phosphate using high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution as raw materials, thereby solving the problem of resource utilization of iron elements in high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution, and ultimately obtaining high-value-added battery-grade iron phosphate products, etc.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing battery-grade iron phosphate using high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution as raw materials includes the following steps:

[0008] (1) Add the high-pressure hydrolysis product powder of cobalt-iron alloy acid leaching solution to deionized water, mix and stir, then add phosphoric acid solution, stir evenly to obtain a yellow mixed solution, heat to react, filter to obtain a clear solution, and control the pH value of the solution to 1.10-1.20;

[0009] (2) Add reduced iron powder to the obtained clear solution while stirring, then add H2O2, continue stirring, and then filter;

[0010] (3) Adjust the pH of the solution obtained after filtration in step (2) to between 2.85 and 3.50 to obtain a white precipitate. Filter, wash and dry the precipitate to obtain battery-grade iron phosphate FePO4 product.

[0011] Furthermore, in step (1), the concentration of the phosphoric acid solution is 35-45 wt%.

[0012] Furthermore, in step (1), the heating reaction is carried out at a temperature of 100-110℃ for 1-3 hours.

[0013] Furthermore, in step (1), the heating reaction is carried out at a temperature of 105°C for 2 hours.

[0014] Furthermore, in step (2), the amount of reduced iron powder added is about 4 times the mass of the powder produced by high-pressure hydrolysis of cobalt-iron alloy acid leaching solution. The reduced iron powder consumes excess phosphoric acid, and at this time the pH value of the solution is between 1.50 and 1.70.

[0015] Furthermore, in step (2), the amount of H2O2 added is 50-70% of the mass of the cobalt-iron alloy acid leaching solution high-pressure hydrolysis product powder, which can be selected as 60%, and its concentration is 25-35wt%.

[0016] Furthermore, in step (2), the stirring time is continued for 50-70 minutes, and the stirring temperature is room temperature.

[0017] Furthermore, in step (3), the reagent used to adjust the pH value is ammonia.

[0018] Furthermore, in step (3), the concentration of the ammonia solution is 8-12 wt%. For example, the concentration of the ammonia solution is 10 wt%.

[0019] Existing technologies generally use mixed acids to dissolve cobalt concentrate or cobalt alloys. This consumes costly acids (sulfuric acid, hydrochloric acid, and nitric acid, etc.), and the residual mixed acid increases the amount of alkaline regulator needed when adjusting the pH, thus increasing the cost of battery-grade iron phosphate preparation. This invention directly uses phosphoric acid to react with the high-pressure hydrolysis products of cobalt-iron acid leaching solution to prepare battery-grade iron phosphate. This reduces the cost of pH regulators and avoids the introduction of sulfate and chloride anions into the reaction system during the mixed acid dissolution process. These anions are difficult to remove during the final washing process of battery-grade iron phosphate. Cobalt concentrate or cobalt alloys contain many impurity elements (Al, Si, and Ca, etc.), while battery-grade iron phosphate requires impurity levels at the ppm level, presenting a high technical barrier and requiring highly effective impurity removal methods, while also considering the cost of battery-grade iron phosphate preparation. This invention directly utilizes the high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution to react with phosphoric acid to prepare battery-grade iron phosphate. This not only effectively controls the content of impurity elements but also significantly reduces production costs and the difficulty of washing the iron phosphate product.

[0020] Because the high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution contain high levels of chromium (Cr% = 0.127) and calcium (Ca% = 0.118), while battery-grade iron phosphate requires relatively low levels of chromium (Cr% ≤ 0.005) and calcium (Ca% ≤ 0.005), preparing battery-grade iron phosphate using cobalt-iron alloy acid leaching solution as raw material presents a high technical challenge. The present invention involves first dissolving the high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution in phosphoric acid. Phosphoric acid is a moderately strong acid, and appropriate heating can dissolve the high-pressure hydrolysis products, resulting in iron phosphate that dissolves in excess phosphoric acid. The pH of the solution is controlled at 1.10-1.20, at which point substances insoluble in phosphoric acid in the high-pressure hydrolysis products can be removed by filtration. Then, an appropriate amount of reduced iron powder is added to the purified, clear, and transparent solution to neutralize the excess phosphoric acid. Next, add H2O2 to the solution, continue stirring and filtering. H2O2 can oxidize ferrous ions to ferric ions, increasing the iron-to-phosphorus ratio of the final battery-grade iron phosphate product. Then, adjust the pH of the solution to between 2.85 and 3.50 with ammonia. At this point, a large amount of white precipitate is produced. Filter, wash and dry the precipitate to finally obtain the battery-grade iron phosphate FePO4 product.

[0021] The main feature of this invention is that it uses the high-pressure hydrolysis product of cobalt-iron alloy acid leaching solution as raw material, and removes impurity elements from the high-pressure hydrolysis product through a dissolution-impurity removal-oxidation-precipitation strategy to obtain battery-grade iron phosphate FePO4 product. No related technology has been reported.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) Using the high-pressure hydrolysis product of cobalt-iron alloy acid leaching solution as raw material, battery-grade iron phosphate FePO4 product was prepared by dissolving-removing impurities-oxidizing-precipitating process route and controlling reaction conditions and parameters. The prepared battery-grade iron phosphate is a white powder product.

[0024] (2) By controlling the pH value of the solution, impurity elements such as calcium and chromium are removed, and ferrous ions are oxidized by H2O2 to improve the iron-phosphorus ratio of iron phosphate products. This technology is simple and effective, and no other impurity ions are introduced in the whole process. The prepared battery-grade iron phosphate FePO4 products have high purity.

[0025] (3) The method of the present invention is applicable to the preparation of battery-grade iron phosphate products from most iron-containing waste solids. The dissolution-impurity removal-oxidation-precipitation process adopted is universal. The entire reaction process has a low cost and does not require high temperature or high pressure treatment. It has the advantages of low energy consumption and easy industrialization. Attached Figure Description

[0026] Figure 1 This is a process flow diagram of the present invention;

[0027] Figure 2 Optical photograph of a powder sample of cobalt-iron alloy acid leaching product under high pressure hydrolysis;

[0028] Figure 3 An optical photograph of the battery-grade iron phosphate (FePO4) product prepared according to this invention;

[0029] Figure 4 The XRD analysis results are for the battery-grade iron phosphate (FePO4) product prepared according to this invention.

[0030] Figure 5 Scanning electron microscope image of the battery-grade iron phosphate FePO4 product prepared for this invention;

[0031] Figure 6 Transmission electron microscope image of the battery-grade iron phosphate FePO4 product prepared for this invention. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0033] In the following embodiments, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0034] Example 1:

[0035] This embodiment provides a method for preparing battery-grade iron phosphate using high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution as raw materials. The preparation process is as follows: Figure 1 As shown.

[0036] The high-pressure hydrolysis product of the cobalt-iron alloy acid leaching solution is a yellow powder sample. The high-pressure hydrolysis product mainly originates from cobalt-iron slag produced during copper smelting. This slag undergoes reduction roasting, crushing, magnetic separation enrichment, followed by acid leaching with dilute sulfuric acid, high-pressure hydrolysis, separation, and drying. Its optical photograph is shown below. Figure 2 As shown in Table 1, the composition analysis of the high-pressure hydrolysis products used in this embodiment is presented. Table 1 shows that the chromium (Cr% = 0.127) and calcium (Ca% = 0.118) content in the high-pressure hydrolysis products is relatively high, significantly higher than that in battery-grade iron phosphate (Cr% ≤ 0.005) and calcium (Ca% ≤ 0.005). Therefore, it is necessary to remove chromium and calcium during the preparation of battery-grade iron phosphate.

[0037] Table 1

[0038] <![CDATA[Al2O3]]> <![CDATA[SiO2]]> <![CDATA[P2O5]]> <![CDATA[SO3]]> CaO <![CDATA[V2O5]]> <![CDATA[Cr2O3]]> 785.6ppm 387.0ppm 0.280％ 6.457％ 0.118％ 54.9ppm 0.127％ <![CDATA[Fe2O3]]> NiO ZnO <![CDATA[ZrO2]]> <![CDATA[MoO3]]> <![CDATA[Ag2O]]> 85.957％ 0.119％ 403.2ppm 224.8ppm 9.3ppm 0.140％

[0039] In this embodiment, 1g of the high-pressure hydrolysis product of cobalt-iron alloy acid leaching solution was measured and added to 28g of a 40wt% dilute phosphoric acid solution. After mixing and stirring, deionized water was added to bring the volume of the mixture to 200mL. The mixture was heated to 105℃ in an oil bath for 2 hours, and the pH of the solution was controlled at approximately 1.17. The solution was then filtered, and 4g of reduced iron powder was added to the resulting solution to neutralize the excess phosphoric acid. Then, 0.6g of 30wt% H2O2 was added, and the solution was stirred and filtered again. The pH was then adjusted to 2.85 with a 10wt% ammonia solution. At this point, a large amount of white precipitate was produced in the solution. The white precipitate was filtered, washed, and dried to obtain the battery-grade iron phosphate FePO4 product. Figure 3 ).

[0040] The X-ray diffraction (XRD) analysis results of the prepared battery-grade iron phosphate FePO4 product are as follows: Figure 4 As shown. From Figure 4 It can be seen that the diffraction peaks of the prepared product are consistent with the composition of FePO4, and the XRD diffraction peaks of the product are relatively strong, indicating that the prepared battery-grade iron phosphate FePO4 product has good crystallinity. Scanning electron microscope (SEM) images of the prepared FePO4 product are shown below. Figure 5 As shown. From Figure 5 As can be seen, the prepared FePO4 product consists of flower-like microspheres with a size of approximately 20 μm. The FePO4 microspheres are uniform in size and exhibit spherical morphology. High-magnification SEM reveals that the FePO4 microspheres are composed of numerous plate-like structures. Transmission electron microscopy (TEM) images of the prepared FePO4 product are shown below. Figure 6 As shown. From Figure 6 It can be seen that the prepared FePO4 microspheres are composed of many sheet-like structures with a length of several hundred nanometers and a thickness of tens of nanometers.

[0041] The inductively coupled plasma atomic emission spectrometry (ICP) analysis of the battery-grade iron phosphate (FePO4) product prepared above is shown in Table 2. As can be seen from Table 2, calcium and chromium impurities in the FePO4 product can be effectively controlled, and the contents of other impurity elements are also within the standard range for battery-grade iron phosphate. The prepared iron phosphate product has an Fe:P ratio of 0.9824. Therefore, the battery-grade iron phosphate prepared by this invention using high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution as raw materials has high quality and shows significant application potential in the resource utilization of iron-containing waste solids such as high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution.

[0042] Table 2

[0043] Al％ Ca% Co% Cr％ Cu% K％ Mg% Na% 0.0155 0.005 0.0002 0.00252 Not detected 0.0028 Not detected 0.0053 P％ Ni% Fe% Mn% Ti% Zn% Pb% Fe:P ratio 17.43 0.0007 30.88 0.0052 0.0258 0.0018 Not detected 0.9824

[0044] Example 2:

[0045] In this embodiment, 1g of the high-pressure hydrolysis product of the cobalt-iron alloy acid leaching solution was measured and added to 28g of a 40wt% dilute phosphoric acid solution. After mixing the high-pressure hydrolysis product with the dilute phosphoric acid, stirring was continued, and then deionized water was added to control the total volume of the mixture solution at 200mL. The mixture was then heated to 105℃ in an oil bath, with the pH of the solution controlled at approximately 1.17, and the reaction time was 2 hours. The solution was then filtered, and 4g of reduced iron powder was added to the solution. Excess phosphoric acid would react with the reduced iron powder. Then, 0.6g of 30wt% H2O2 was added, and the solution was stirred continuously. After thorough stirring and filtration, the pH value was adjusted to 3.50 with a 10wt% ammonia solution. At this point, a large amount of white precipitate was obtained. The white precipitate was then filtered, washed, and dried to obtain the battery-grade iron phosphate (FePO4) product.

[0046] The ICP analysis results of the prepared iron phosphate (FePO4) product are shown in Table 3. As can be seen from Table 3, the prepared iron phosphate product has a Fe:P ratio of 0.9830, meeting the requirements for battery-grade iron phosphate. Increasing the solution pH from 2.85 to 3.50 causes further precipitation of iron ions, resulting in an increase in the iron-to-phosphorus ratio from 0.9824 to 0.9830. Therefore, solution pH is also an important reaction parameter for controlling the iron-to-phosphorus ratio in the iron phosphate product.

[0047] Table 3

[0048] Al％ Ca% Co% Cr％ Cu% K％ Mg% Na% 0.0136 0.0049 0.0003 0.00247 Not detected 0.0021 Not detected 0.0048 P％ Ni% Fe% Mn% Ti% Zn% Pb% Fe:P ratio 17.35 0.0006 30.75 0.0041 0.0223 0.0012 Not detected 0.9830

[0049] Comparative Example 1:

[0050] Compared with Example 1, it is largely the same, except that the step of adding Fe powder is omitted.

[0051] 1g of the high-pressure hydrolysis product of cobalt-iron alloy acid leaching solution was mixed with 28g of a 40wt% dilute phosphoric acid solution, and then deionized water was added to a final volume of 200mL. The mixture was heated to 105℃ in an oil bath for 2 hours, with the pH of the solution controlled at approximately 1.17. The solution was then filtered. No reduced iron powder was added to the resulting solution; instead, 0.6g of 30wt% H₂O₂ was added directly. After further stirring and filtration, the pH was adjusted to 2.85 using a 10wt% ammonia solution. A large amount of white precipitate was produced at this point. The white precipitate was filtered, washed, and dried to obtain the battery-grade iron phosphate (FePO₄) product.

[0052] The ICP analysis results of the prepared iron phosphate (FePO4) product are shown in Table 4. Table 4 shows that without the addition of reduced iron powder, the calcium and chromium content in the iron phosphate product is relatively high, while the iron content is relatively low, with an iron-to-phosphorus ratio of only 0.618. This indicates that there was an excess of phosphoric acid during the reaction, resulting in a large number of byproducts and preventing the production of a battery-grade iron phosphate product with a high iron-to-phosphorus ratio.

[0053] Table 4

[0054] Al％ Ca% Co% Cr％ Cu% K％ Mg% Na% 0.004 0.018 Not detected 0.019 Not detected 0.0035 Not detected 0.0057 P％ Ni% Fe% Mn% Ti% Zn% Pb% Fe:P ratio 19.341 0.0005 21.585 0.0067 0.0236 0.0023 Not detected 0.618

[0055] Comparative Example 2:

[0056] The majority of the results are the same as in Example 1, except that the pH value of the subsequent ammonia water adjustment is changed to 3.8.

[0057] 1g of the high-pressure hydrolysis product of cobalt-iron alloy acid leaching solution was mixed with 28g of a 40wt% dilute phosphoric acid solution. After mixing and stirring, deionized water was added to bring the volume of the mixture to 200mL. The mixture was then heated to 105℃ in an oil bath for 2 hours, with the pH of the solution controlled at approximately 1.17. The solution was then filtered, and 4g of reduced iron powder was added to the resulting solution, followed by 0.6g of 30% H2O2. The solution was stirred and filtered again, and the pH was adjusted to 3.80 using a 10wt% ammonia solution. At this point, a large amount of white precipitate was formed in the solution. The white precipitate was filtered, washed, and dried to obtain the battery-grade iron phosphate (FePO4) product.

[0058] The ICP analysis results of the prepared ferric phosphate (FePO4) product are shown in Table 5. As can be seen from Table 5, the iron-to-phosphorus ratio decreased as the solution pH increased from 3.50 to 3.80. This is because excess ammonia water complexes with iron ions, forming water-soluble complexes, thereby reducing the iron content in the precipitated ferric phosphate product.

[0059] Table 5

[0060] Al％ Ca% Co% Cr％ Cu% K％ Mg% Na% 0.0135 0.0047 0.0003 0.00231 Not detected 0.0022 Not detected 0.0048 P％ Ni% Fe% Mn% Ti% Zn% Pb% Fe:P ratio 17.28 0.0005 29.75 0.0049 0.0213 0.0014 Not detected 0.953

[0061] Comparative Example 3:

[0062] 1g of the high-pressure hydrolysis product of cobalt-iron alloy acid leaching solution was added to 28g of a 40wt% dilute phosphoric acid solution. After mixing and stirring, deionized water was added to bring the volume of the mixture to 200mL. The mixture was then heated in an oil bath to 105℃ for 2 hours, with the pH of the solution controlled at 1.10-1.20. After the reaction, the solution was filtered, and 4g of reduced iron powder was added to the resulting solution, followed by 0.6g of 30% H2O2. The solution was stirred and filtered again, and then the pH was adjusted to 2.0 with a 10wt% ammonia solution. At this point, a white precipitate appeared in the solution. The white precipitate was filtered, washed, and dried to obtain the battery-grade iron phosphate (FePO4) product.

[0063] The ICP analysis results for the preparation of ferric phosphate (FePO4) products are shown in Table 6. As can be seen from Table 6, although a relatively large amount of white ferric phosphate product is obtained at a solution pH of 2.0, the iron precipitation rate in the solution is low, and the iron-to-phosphorus ratio is somewhat low.

[0064] Table 6

[0065] Al％ Ca% Co% Cr％ Cu% K％ Mg% Na% 0.0118 0.0043 0.0004 0.00227 Not detected 0.0023 Not detected 0.0045 P％ Ni% Fe% Mn% Ti% Zn% Pb% Fe:P ratio 17.38 0.0007 28.34 0.0042 0.0201 0.0011 Not detected 0.903

[0066] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing battery-grade iron phosphate using high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution as raw materials, characterized in that, Includes the following steps: (1) Add the high-pressure hydrolysis product powder of cobalt-iron alloy acid leaching solution to deionized water, mix and stir, then add phosphoric acid solution, stir evenly to obtain a yellow mixed solution, heat to react, filter to obtain a clear solution, and control its pH value to 1.10-1.20; (2) Add reduced iron powder to the obtained clear solution while stirring, then add H2O2, continue stirring, and then filter; (3) Adjust the pH of the solution obtained after filtration in step (2) to between 2.85 and 3.50 to obtain a white precipitate. Filter, wash and dry the precipitate to obtain battery-grade iron phosphate FePO4 product. In step (1), the heating reaction is carried out at a temperature of 100-110℃ for 1-3 hours; In step (2), the amount of reduced iron powder added is such that the pH value of the solution after addition is between 1.50 and 1.

70. In step (2), the mass of H2O2 added is 50-70% of the mass of the cobalt-iron alloy acid leaching solution high-pressure hydrolysis product powder, and its concentration is 25-35wt%.

2. The method for preparing battery-grade iron phosphate using high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution as raw materials according to claim 1, characterized in that, In step (1), the concentration of the phosphoric acid solution is 35-45 wt%.

3. The method for preparing battery-grade iron phosphate using high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution as raw materials according to claim 1, characterized in that, In step (1), the heating reaction is carried out at a temperature of 105°C for 2 hours.

4. The method for preparing battery-grade iron phosphate using high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution as raw materials according to claim 1, characterized in that, In step (2), the stirring time is 50-70 minutes and the stirring temperature is room temperature.

5. The method for preparing battery-grade iron phosphate using high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution as raw materials according to claim 1, characterized in that, In step (3), the reagent used to adjust the pH value is ammonia.

6. The method for preparing battery-grade iron phosphate using high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution as raw materials according to claim 5, characterized in that, In step (3), the concentration of the ammonia water is 8-12 wt%.

7. The method for preparing battery-grade iron phosphate using high-pressure hydrolysis products of cobalt-iron alloy acid leaching solution as raw materials according to claim 6, characterized in that, In step (3), the concentration of the ammonia water is 10 wt%.

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