Method for preparing battery-grade iron phosphate material by utilizing regenerated iron phosphate leachate through one-step method

Abstract

A method for preparing a battery-grade iron phosphate material by using a regenerated iron phosphate leachate through a one-step method belongs to the field of iron phosphate preparation, and comprises the following steps: S1, preparing the regenerated iron phosphate leachate, a phosphoric acid solution and an ammonia water solution; s2, pure water is poured into the reaction kettle, and a base solution is obtained; s3, the base solution is heated, the regenerated iron phosphate leaching solution and the ammonia water solution are added, and slurry A is obtained after reaction; adjusting the pH value of the slurry A to be less than or equal to 1.5; s4, adding a phosphoric acid solution into the slurry A, heating the slurry A, and carrying out heat preservation to obtain slurry B; s5, filtering, washing, drying and calcining the slurry B to obtain anhydrous iron phosphate; the battery-grade iron phosphate material is prepared through a one-step method, iron and phosphorus resources in the regenerated iron phosphate leachate are fully utilized, and resource waste caused by multi-step reaction and complex operation in the traditional preparation process is avoided.

Description

Technical Field

[0001] The invention belongs to the field of iron phosphate preparation, and specifically is a method for preparing battery-grade iron phosphate material by utilizing regenerated iron phosphate leaching solution in one step. Background Art

[0002] As a key component of lithium-ion battery cathode materials, the quality and performance of iron phosphate (FePO4) directly affect the overall performance of the battery. With the increasing global attention to sustainable energy and environmental protection technologies, the lithium-ion battery industry has ushered in unprecedented development opportunities. However, the traditional method of preparing iron phosphate often requires multi-step reactions and complex operations, which not only has a long process flow but also high production costs. Therefore, it is of great significance to develop an efficient and simple one-step method for preparing iron phosphate, which can significantly improve production efficiency, reduce production costs, and help promote the development of the new energy materials industry.

[0003] Regenerated iron phosphate leachate mainly comes from the recycling process of waste lithium-ion batteries, which contains a large amount of trivalent iron ions and phosphate ions, as well as other metal ions, organic matter and other impurities. Traditionally, regenerated iron phosphate leachate is often treated as waste, which not only wastes precious resources, but also may cause potential pollution to the environment.

[0004] Therefore, how to recycle and reuse the regenerated iron phosphate leaching solution to prepare iron phosphate has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for preparing an iron phosphate material with a short process flow, low cost and full and round crystal form. The technical solution provided by the present invention is simple to operate, has good process stability and low cost. The prepared iron phosphate particles are full and round, with high purity, and are suitable for industrial production. The details are as follows: A method for preparing a battery-grade iron phosphate material by using a regenerated iron phosphate leachate in one step, comprising the following steps: S1, prepare regenerated iron phosphate leaching solution, phosphoric acid solution, ammonia solution, and set aside; the iron-phosphorus feed ratio of the regenerated iron phosphate leaching solution is 0.95-1.05; S2, pouring pure water into the reaction kettle to obtain a pure water solution, i.e., the base solution; S3, heating the above-mentioned base liquid to 20-35°C, adding the regenerated iron phosphate leachate and ammonia solution at a rate of 50-100mL / min and 10-40mL / min under continuous stirring, and reacting for 10-30min to obtain slurry A composed of basic ammonium ferric phosphate; the amount of ammonia solution added is to adjust the pH of slurry A to 1-1.5; S4, adding phosphoric acid solution to slurry A, heating slurry A once, keeping it warm once, heating it twice, keeping it warm twice, to obtain a pink slurry B; S5. After filtering, washing and drying the slurry B, dihydrate iron phosphate is obtained. After calcining the dihydrate iron phosphate, anhydrous iron phosphate is obtained.

[0006] Preferably, in step S1, the sum of the concentrations of iron and phosphorus in the regenerated iron phosphate leachate is 1.0-1.8 mol / L.

[0007] Preferably, in step S1, the regenerated iron phosphate leachate is prepared by dissolving ferrophosphorus slag and waste iron phosphate after lithium extraction from the battery, and the preparation method is: mix the ferrophosphorus slag and waste iron phosphate in a mass ratio of 3:1, add an equal volume of water to make a slurry and continue to stir evenly, add 2 times the volume of the slurry acid, heat to 65°C, keep warm for 2 hours, filter, add sodium hydroxide to the filtered filtrate, filter, add an equal volume of water to the filtered filter cake to make a slurry, continue to add sulfuric acid, the amount of sulfuric acid added is 0.6 of the molar amount of iron in the ferrophosphorus slag and the waste iron phosphate, and at the same time add a certain amount of phosphorus-containing mother liquor to obtain a regenerated iron phosphate leachate with an iron-phosphorus feed ratio of 0.95.

[0008] Preferably, in step S1, the molar ratio of the ammonia water in the ammonia water solution to the molar ratio of the iron element in the regenerated iron phosphate leachate is n(Fe):n(NH3•H2O)=1:0.2-1.2.

[0009] Preferably, in step S1, the concentration of the phosphoric acid solution is 60-85wt%, and the concentration of the ammonia solution is 20-25wt%.

[0010] Preferably, in step S3, the mass ratio of the regenerated iron phosphate leachate to pure water is 3:1.

[0011] Preferably, in step S3, the regenerated iron phosphate leaching solution and the ammonia solution are added in a dual-stream manner.

[0012] Preferably, in step S4, the molar ratio of phosphorus in the added phosphoric acid solution to iron in the regenerated iron phosphate leachate should be controlled to be n(P):n(Fe)=0.05-0.15:1.

[0013] Preferably, in step S4, the temperature is raised to 40-70°C for the first time and kept warm for 20-80 minutes, and then the temperature is raised to 90-100°C for the second time. After the color of the slurry changes from yellow to pinkish white, the temperature is kept warm for a second time for 60-150 minutes to obtain pinkish white slurry B.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention prepares battery-grade iron phosphate material through a one-step method, which makes full use of the iron and phosphorus resources in the regenerated iron phosphate leachate, avoiding the waste of resources caused by multi-step reactions and complex operations in the traditional preparation process. At the same time, the method of the present invention effectively reduces the waste discharge in the treatment process of waste lithium-ion batteries, converts the raw iron phosphate leachate into valuable iron phosphate material, and reduces environmental pollution.

[0015] 2. The present invention provides a method for preparing a battery-grade iron phosphate material by using a regenerated iron phosphate leachate in a one-step process, wherein pure water is used as a base liquid, and ammonia water and a regenerated iron phosphate leachate are used as a feeding liquid. The synthesis pH is controlled to change the pH value of the system, and a small amount of phosphoric acid solution is continuously added, so that the generated basic ammonium ferric phosphate and part of the regenerated iron phosphate leachate complete the transformation from the ammonium ferric phase to the iron phosphate phase under low-acid conditions; the low-temperature insulation condition is once again used to accelerate the dissolution and phase transformation of the basic ammonium ferric phosphate phase, and strengthen the transformation under low-acid conditions, thereby preparing an iron phosphate material with controllable physical and chemical indicators such as morphology and iron-phosphorus ratio.

[0016] 3. Compared with the existing preparation technology of iron phosphate materials, the present invention realizes the one-step preparation of iron phosphate materials by controlling the pH of the slurry, thereby reducing the reaction time, operation steps and the amount of phosphoric acid used, and realizing phosphorus with controllable crystal form. At the same time, especially in reducing the amount of phosphoric acid used, the present invention greatly saves the production cost of iron phosphate.

[0017] 4. In the present invention, the preparation process of ferric phosphate dihydrate is completed continuously in one reactor, and there is no secondary transfer, washing and re-slurrying of the slurry, thereby shortening the production cycle and improving the overall production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 50K, 10K, and 3K scanning electron micrographs of anhydrous iron phosphate prepared in Example 1 of the present invention; Figure 2 The scanning electron microscope images of 50K, 10K and 3K anhydrous iron phosphate prepared in Comparative Example 1 of the present invention are shown; Figure 3 The scanning electron microscope images of 50K, 10K and 3K anhydrous iron phosphate prepared in Comparative Example 2 of the present invention are shown; Figure 4 The scanning electron microscope images of 50K, 10K and 3K anhydrous iron phosphate prepared in Comparative Example 3 of the present invention are shown; Figure 5 The scanning electron microscope images of 50K, 10K and 3K anhydrous iron phosphate prepared in Comparative Example 4 of the present invention are shown; Figure 6 The XRD diagrams of ferric phosphate dihydrate prepared in Example 1 and Comparative Examples 1-4 of the present invention are shown. DETAILED DESCRIPTION

[0019] Example 1 A method for preparing a battery-grade iron phosphate material by using a regenerated iron phosphate leachate in one step, comprising the following steps: S1, prepare regenerated iron phosphate leaching solution, phosphoric acid solution and ammonia solution with an iron-phosphorus feed ratio of 0.95 for standby use; S2, pouring pure water into the reaction kettle to obtain a pure water solution, i.e., the base solution; S3, heating the above-mentioned base liquid to 20°C, adding the regenerated iron phosphate leachate and ammonia solution at a rate of 50mL / min and 10-40mL / min under continuous stirring, and obtaining slurry A composed of basic ammonium iron phosphate after reacting for 10min; the amount of ammonia solution added is such that the pH of slurry A is adjusted to 1.15; S4, adding phosphoric acid solution to slurry A, heating slurry A once, keeping it warm once, heating it twice, keeping it warm twice, to obtain a pink slurry B; S5. After filtering, washing and drying the slurry B, dihydrate iron phosphate is obtained. After calcining the dihydrate iron phosphate, anhydrous iron phosphate is obtained.

[0020] Moreover, in step S1, the sum of the concentrations of iron and phosphorus in the regenerated iron phosphate leachate is 1.0 mol / L.

[0021] Moreover, in step S1, the regenerated iron phosphate leachate is prepared by dissolving ferrophosphorus slag and waste iron phosphate after lithium extraction from the battery, and the preparation method is: the ferrophosphorus slag and the waste iron phosphate are mixed evenly in a mass ratio of 3:1, an equal volume of water is added to make a slurry and continue to stir evenly, 2 times the volume of the slurry is added, the temperature is raised to 65°C, and after keeping warm for 2 hours, it is filtered, and sodium hydroxide is added to the filtered filtrate, filtered, and the filtered filter cake is added to an equal volume of water to make a slurry, and sulfuric acid is continued to be added, and the amount of sulfuric acid added is 0.6 of the molar amount of iron in the ferrophosphorus slag and the waste iron phosphate. At the same time, a certain amount of phosphorus-containing mother liquor is added to obtain a regenerated iron phosphate leachate with an iron-phosphorus feed ratio of 0.95.

[0022] Moreover, in step S1, the molar ratio of the ammonia water in the ammonia water solution to the molar ratio of the iron element in the regenerated iron phosphate leaching solution is n(Fe):n(NH3•H2O)=1:0.2.

[0023] Moreover, in step S3, the mass ratio of the regenerated iron phosphate leaching solution to pure water is 3:1.

[0024] Moreover, in step S4, the molar ratio of phosphorus in the added phosphoric acid solution to iron in the regenerated iron phosphate leaching solution should be controlled to be n(P):n(Fe)=0.05:1.

[0025] Moreover, in step S1, the concentration of the phosphoric acid solution is 60 wt % and the concentration of the ammonia solution is 20 wt %.

[0026] Moreover, in step S3, the regenerated iron phosphate leaching solution and the ammonia solution are added in a dual-stream manner.

[0027] Moreover, in step S4, the temperature is raised to 40°C for the first time and kept for 20 minutes, and then raised to 90°C for the second time. After the color of the slurry changes from yellow to pinkish white, the temperature is kept for the second time for 60 minutes to obtain pinkish white slurry B.

[0028] Example 2 A method for preparing a battery-grade iron phosphate material by using a regenerated iron phosphate leachate in one step, comprising the following steps: S1, prepare regenerated iron phosphate leaching solution, phosphoric acid solution and ammonia solution with an iron-phosphorus feed ratio of 1.05 for standby use; S2, pouring pure water into the reaction kettle to obtain a pure water solution, i.e., the base solution; S3, heating the above-mentioned base liquid to 35°C, adding the regenerated iron phosphate leachate and ammonia solution at a rate of 100 mL / min and 40 mL / min under continuous stirring, and obtaining slurry A composed of basic ammonium ferric phosphate after reacting for 30 minutes; the amount of ammonia solution added is such that the pH of slurry A is adjusted to 1.25; S4, adding phosphoric acid solution to slurry A, heating slurry A once, keeping it warm once, heating it twice, keeping it warm twice, to obtain a pink slurry B; S5. After filtering, washing and drying the slurry B, dihydrate iron phosphate is obtained. After calcining the dihydrate iron phosphate, anhydrous iron phosphate is obtained.

[0029] Moreover, in step S1, the sum of the concentrations of iron and phosphorus in the regenerated iron phosphate leachate is 1.8 mol / L.

[0030] Moreover, in step S1, the regenerated iron phosphate leachate is prepared by dissolving ferrophosphorus slag and waste iron phosphate after lithium extraction from the battery, and the preparation method is: the ferrophosphorus slag and the waste iron phosphate are mixed evenly in a mass ratio of 3:1, an equal volume of water is added to make a slurry and continue to stir evenly, 2 times the volume of the slurry is added, the temperature is raised to 65°C, and after keeping warm for 2 hours, it is filtered, and sodium hydroxide is added to the filtered filtrate, filtered, and the filtered filter cake is added to an equal volume of water to make a slurry, and sulfuric acid is continued to be added, and the amount of sulfuric acid added is 0.6 of the molar amount of iron in the ferrophosphorus slag and the waste iron phosphate. At the same time, a certain amount of phosphorus-containing mother liquor is added to obtain a regenerated iron phosphate leachate with an iron-phosphorus feed ratio of 0.95.

[0031] Moreover, in step S1, the concentration of the phosphoric acid solution is 85 wt %, and the concentration of the ammonia solution is 25 wt %.

[0032] Moreover, in step S1, the molar ratio of the ammonia water in the ammonia water solution to the molar ratio of the iron element in the regenerated iron phosphate leaching solution is n(Fe):n(NH3•H2O)=1:1.2.

[0033] Moreover, in step S3, the mass ratio of the regenerated iron phosphate leaching solution to pure water is 3:1.

[0034] Moreover, in step S3, the regenerated iron phosphate leaching solution and the ammonia solution are added in a dual-stream manner.

[0035] Moreover, in step S4, the molar ratio of phosphorus in the added phosphoric acid solution to iron in the regenerated iron phosphate leaching solution should be controlled to be n(P):n(Fe)=0.15:1.

[0036] Moreover, in step S4, the temperature is raised to 70°C for the first time and kept for 80 minutes, and then raised to 100°C for the second time. After the color of the slurry changes from yellow to pinkish white, the temperature is kept for the second time for 150 minutes to obtain pinkish white slurry B.

[0037] Example 3 A method for preparing a battery-grade iron phosphate material by using a regenerated iron phosphate leachate in one step, comprising the following steps: S1, prepare regenerated iron phosphate leaching solution, phosphoric acid solution and ammonia solution with an iron-phosphorus feed ratio of 1.0 for standby use; S2, pouring pure water into the reaction kettle to obtain a pure water solution, i.e., the base solution; S3, the base liquid is heated to 28°C, and under continuous stirring, the regenerated iron phosphate leachate and the ammonia solution are added at a rate of 80 mL / min and 25 mL / min, respectively, and after reacting for 20 minutes, a slurry A composed of basic ammonium ferric phosphate is obtained; the amount of the ammonia solution added is such that the pH of the slurry A is adjusted to 1.35; S4, adding phosphoric acid solution to slurry A, heating slurry A once, keeping it warm once, heating it twice, keeping it warm twice, to obtain a pink slurry B; S5. After filtering, washing and drying the slurry B, dihydrate iron phosphate is obtained. After calcining the dihydrate iron phosphate, anhydrous iron phosphate is obtained.

[0038] Moreover, in step S1, the sum of the concentrations of iron and phosphorus in the regenerated iron phosphate leachate is 1.4 mol / L.

[0039] Moreover, in step S1, the regenerated iron phosphate leachate is prepared by dissolving ferrophosphorus slag and waste iron phosphate after lithium extraction from the battery, and the preparation method is: the ferrophosphorus slag and the waste iron phosphate are mixed evenly in a mass ratio of 3:1, an equal volume of water is added to make a slurry and continue to stir evenly, 2 times the volume of the slurry is added, the temperature is raised to 65°C, and after keeping warm for 2 hours, it is filtered, and sodium hydroxide is added to the filtered filtrate, filtered, and the filtered filter cake is added to an equal volume of water to make a slurry, and sulfuric acid is continued to be added, and the amount of sulfuric acid added is 0.6 of the molar amount of iron in the ferrophosphorus slag and the waste iron phosphate. At the same time, a certain amount of phosphorus-containing mother liquor is added to obtain a regenerated iron phosphate leachate with an iron-phosphorus feed ratio of 0.95.

[0040] Moreover, in step S1, the molar ratio of the ammonia water in the ammonia water solution to the molar ratio of the iron element in the regenerated iron phosphate leaching solution is n(Fe):n(NH3•H2O)=1:0.6.

[0041] Moreover, in step S3, the mass ratio of the regenerated iron phosphate leaching solution to pure water is 3:1.

[0042] Moreover, in step S4, the molar ratio of phosphorus in the added phosphoric acid solution to iron in the regenerated iron phosphate leaching solution should be controlled to be n(P):n(Fe)=0.1:1.

[0043] Moreover, in step S1, the concentration of the phosphoric acid solution is 70 wt % and the concentration of the ammonia solution is 23 wt %.

[0044] Moreover, in step S3, the regenerated iron phosphate leaching solution and the ammonia solution are added in a dual-stream manner.

[0045] Moreover, in step S4, the temperature is raised to 55°C for the first time and kept warm for 50 minutes, and then raised to 95°C for the second time. After the color of the slurry changes from yellow to pinkish white, the temperature is kept warm for the second time for 100 minutes to obtain pinkish white slurry B.

[0046] Example 4 The difference between this embodiment and embodiment 3 is that in step S3, the pH of slurry A is 1.45.

[0047] Comparative Example 1 In this comparative example, except that the pH of slurry A was adjusted to 0.95, everything else was the same as Example 1.

[0048] Comparative Example 2 In this comparative example, except that the pH of slurry A was adjusted to 1.55, everything else was the same as Example 1.

[0049] Comparative Example 3 In this comparative example, except that the pH of slurry A was adjusted to 1.65, everything else was the same as Example 1.

[0050] Comparative Example 4 In this comparative example, except that the pH of slurry A was adjusted to 1.75, everything else was the same as Example 1.

[0051] Experimental Section

[0052] Experiment 1 The anhydrous ferric phosphate prepared in Example 1 and Comparative Examples 1-4 was scanned by electron microscope. Figure 1-4 , Figure 1 50K, 10K, and 3K scanning electron micrographs of anhydrous iron phosphate prepared in Example 1 of the present invention; Figure 2 The scanning electron microscope images of 50K, 10K and 3K anhydrous iron phosphate prepared in Comparative Example 1 of the present invention are shown; Figure 3 The scanning electron microscope images of 50K, 10K and 3K anhydrous iron phosphate prepared in Comparative Example 2 of the present invention are shown; Figure 4 The scanning electron microscope images of 50K, 10K and 3K anhydrous iron phosphate prepared in Comparative Example 3 of the present invention are shown; Figure 5 Scanning electron micrographs of 50 K, 10 K, and 3 K anhydrous iron phosphate prepared in Comparative Example 4 of the present invention. from Figure 1-5 It can be seen that when the pH of slurry A is 1.15 ( Figure 1 ), the anhydrous ferric phosphate particles are clear, without impurities, and the iron-phosphorus ratio is normal; when the pH of slurry A is 0.95 ( Figure 2 ), different iron phosphate phases were produced at lower pH values; when the pH of slurry A was greater than 1.5, basic ammonium iron phosphate phase and other transition phases appeared as the pH of slurry A increased ( Figure 2-5 ), which indicates that at higher pH values, the synthesis reaction of iron phosphate is affected, resulting in the production of different iron phosphate phases; when the pH is 1.75 ( Figure 3-5 ), basic ammonium ferric phosphate is almost not converted, and a small part is converted into transition phase.

[0053] Experiment 2 The phases of the iron phosphate dihydrate prepared in Example 1 and Comparative Examples 1-4 were tested by X-ray diffractometer (XRD). Figure 6 As shown in the figure, it can be seen that, compared with Examples 1-4, the pH is too high or too low, and iron ammonium peaks appear in XRD, and the iron ammonium peak intensity of Comparative Example 4 is the highest.

[0054] Experiment 3 The anhydrous ferric phosphate prepared in Example 1 and Comparative Examples 1-4 was subjected to physical and chemical analysis. The iron content and phosphorus content were tested by XG207 iron content analyzer and titration method, the particle size of the anhydrous ferric phosphate was tested by nanoparticle size and Zeta potential analyzer (DLS), and the specific surface area of ​​the anhydrous ferric phosphate was tested by a fully automatic specific surface and porosity analyzer (BET). The results are shown in Table 1.

[0055] Table 1 Physical and chemical indicators

[0056] As can be seen from Table 1, in Comparative Examples 1 and 2, when the pH of slurry A is adjusted to be lower than the lower limit of the embodiment or slightly higher than the embodiment, the iron content of anhydrous ferric phosphate is low, the phosphorus content is high, and the specific value after calcination is lower than the table. This is because when the pH of slurry A is slightly low, the slurry contains more free iron ions and phosphate ions, and more phosphoric acid needs to be consumed when heating at this time; similarly, when the feed pH is slightly high, more phosphoric acid is required to dissolve basic ammonium ferric phosphate, so during the temperature increase and conversion process, the crystals cannot fully grow and develop; when the feed pH is much higher than the embodiment (Comparative Example 3, Comparative Example 4), the undissolved basic ammonium ferric phosphate cannot be completely converted into dihydrate ferric phosphate, thereby obtaining a mixed phase and an unconverted ammonium ferric phase, and the corresponding Comparative Examples 3 and 4 have high iron content, low phosphorus content, and a high iron-phosphorus ratio. This phase has a small particle size and is not resistant to burning.

[0057] Experiment 4 Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the main impurity components of the anhydrous ferric phosphate of Examples 1-4 and Comparative Examples 1-4. The results are shown in Table 2.

[0058] Table 2 Main impurities

[0059] It can be seen from Table 2 that when the pH of the slurry is 1.15, 1.25, and 1.35, S and Mn impurities are not detected, and the impurity contents of Al and Mg are also small and fluctuate within a small range; when the pH of the slurry is at a lower level (Comparative Example 1, pH=0.95), the impurity content is low or undetectable, and when the pH is higher than the critical value, the impurity content increases exponentially.

Claims

1. A method for preparing battery-grade iron phosphate material using a one-step method of regenerated iron phosphate leachate, characterized in that: The following steps are involved: S1, prepare regenerated iron phosphate leaching solution, phosphoric acid solution, ammonia solution, and set aside; the iron-phosphorus feed ratio of the regenerated iron phosphate leaching solution is 0.95-1.05; S2, pouring pure water into the reaction kettle to obtain a pure water solution, i.e., the base solution; S3, heating the above-mentioned base liquid to 20-35°C, adding the regenerated iron phosphate leachate and ammonia solution at a rate of 50-100 mL / min and 10-40 mL / min under continuous stirring, and reacting for 10-30 minutes to obtain slurry A composed of basic ammonium ferric phosphate; The amount of ammonia solution added is to adjust the pH of slurry A to 1-1.5; S4, adding phosphoric acid solution to slurry A, heating slurry A once, keeping it warm once, heating it twice, keeping it warm twice, to obtain a pink slurry B; S5. After filtering, washing and drying the slurry B, dihydrate iron phosphate is obtained. After calcining the dihydrate iron phosphate, anhydrous iron phosphate is obtained.

2. The method for preparing battery-grade iron phosphate material by one-step method using regenerated iron phosphate leachate according to claim 1, characterized in that: In step S1, the sum of the concentrations of iron and phosphorus in the regenerated iron phosphate leachate is 1.0-1.8 mol / L.

3. The method for preparing battery-grade iron phosphate material by one-step method using regenerated iron phosphate leachate according to claim 1, characterized in that: In step S1, the regenerated iron phosphate leachate is prepared by dissolving ferrophosphorus slag and waste iron phosphate after lithium extraction from the battery, and the preparation method is: the ferrophosphorus slag and the waste iron phosphate are mixed evenly in a mass ratio of 3:1, an equal volume of water is added to make a slurry and continue to stir evenly, 2 times the volume of the slurry is added, the temperature is raised to 65°C, and after keeping warm for 2 hours, it is filtered, sodium hydroxide is added to the filtered filtrate, filtered, and the filtered filter cake is added with an equal volume of water to make a slurry, and sulfuric acid is continued to be added, the amount of sulfuric acid added is 0.6 of the molar amount of iron in the ferrophosphorus slag and the waste iron phosphate, and a certain amount of phosphorus-containing mother liquor is added at the same time to obtain a regenerated iron phosphate leachate with an iron-phosphorus feed ratio of 0.

95.

4. The method for preparing battery-grade iron phosphate material by one-step method using regenerated iron phosphate leachate according to claim 1, characterized in that: In step S1, the molar ratio of the ammonia water in the ammonia water solution to the molar ratio of the iron element in the regenerated iron phosphate leaching solution is n(Fe):n(NH3•H2O)=1:0.2-1.

2.

5. The method for preparing battery-grade iron phosphate material by one-step method using regenerated iron phosphate leachate according to claim 1, characterized in that: In step S1, the concentration of the phosphoric acid solution is 60-85wt%, and the concentration of the ammonia solution is 20-25wt%.

6. The method for preparing battery-grade iron phosphate material by one-step method using regenerated iron phosphate leachate according to claim 1, characterized in that: In step S3, the mass ratio of the regenerated iron phosphate leaching solution to pure water is 3:

1.

7. The method for preparing battery-grade iron phosphate material by one-step method using regenerated iron phosphate leachate according to claim 1, characterized in that: In step S3, the regenerated iron phosphate leaching solution and the ammonia solution are added in a dual-stream manner.

8. The method for preparing battery-grade iron phosphate material by one-step method using regenerated iron phosphate leachate according to claim 1, characterized in that: In step S4, the molar ratio of phosphorus in the added phosphoric acid solution to iron in the regenerated iron phosphate leachate should be controlled to be n(P):n(Fe)=0.05-0.15:

1.

9. The method for preparing battery-grade iron phosphate material by one-step method using regenerated iron phosphate leachate according to claim 1, characterized in that: In step S4, the temperature is raised to 40-70°C for the first time and kept warm for 20-80 minutes, and then the temperature is raised to 90-100°C for the second time. After the color of the slurry changes from yellow to pinkish white, the temperature is kept warm for a second time for 60-150 minutes to obtain pinkish white slurry B.

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