Method for comprehensive recovery of high-impurity lithium phosphate and application thereof

Abstract

The application provides a comprehensive recovery method of high-impurity lithium phosphate, comprising the following steps: S1: preparing acid leaching bottom water with a pH of 1-2 by mixing a ferric sulfate reagent and sulfuric acid; S2: mixing the acid leaching bottom water with high-impurity lithium phosphate, adding sulfuric acid to control the pH to be 1-2.5, and obtaining acid leaching slurry; S3: adding alkali to the acid leaching slurry to control the pH to be 4-4.5, and performing solid-liquid separation to obtain phosphorus-iron slag and lithium-rich solution; the high-impurity lithium phosphate contains impurity elements such as calcium, magnesium, aluminum, nickel, cobalt and manganese. The comprehensive recovery method of high-impurity lithium phosphate can solve the problems in the treatment process of high-impurity lithium phosphate, such as incomplete conversion, large amount of auxiliary materials introduced, high sodium content in the solution, and low recovery rate of valuable metals.

Description

Technical Field

[0001] This invention belongs to the field of wet impurity removal technology, specifically relating to a comprehensive recovery method for high-purity lithium phosphate and its application. Background Technology

[0002] In recent years, lithium batteries have been used more and more widely in the power and energy storage industries. The core element lithium has a low production volume and high price. Therefore, maximizing the recycling and utilization of lithium resources is becoming increasingly important for the development of the lithium battery industry.

[0003] Currently, lithium resources mainly come from spodumene, lepidolite, lithium from salt lakes, and the recycling of spent lithium batteries. Common processes involve producing lithium carbonate and lithium hydroxide products using pyrometallurgical and hydrometallurgical methods. During this process, some impurities need to be removed, and some lithium is lost along with these impurities. A common industry method is to add phosphate to adjust the lithium content and precipitate it, thus enriching and recovering the lithium. However, the recovered lithium phosphate has a high impurity content and is not the lithium carbonate or lithium hydroxide needed in lithium battery cathode materials, requiring further impurity removal and conversion.

[0004] In existing technologies, lithium phosphate treatment generally involves dissolving the lithium phosphate with acid. One method involves dissolving the lithium phosphate with acid followed by conversion with iron, calcium, or aluminum salts. This method, due to the excessive addition of acid, leads to significant consumption of auxiliary materials during the recovery process, particularly resulting in a high sodium content in the converted lithium solution, making subsequent recovery of battery-grade lithium phosphate extremely difficult. Another method involves simultaneously adding slurry-formed lithium phosphate and an iron-containing solution to acidified water. While this reduces the amount of acid, the solubility of iron phosphate remains high in this system, resulting in a significant amount of iron phosphate in the final lithium solution. Iron phosphate recovery is incomplete, and the crude lithium phosphate produced is relatively homogeneous. This method lacks processing for impurities such as calcium and magnesium, and the subsequent process for producing battery-grade lithium carbonate remains traditional. Furthermore, the removal of impurities and product recovery from lithium phosphate containing heavy metals such as nickel, cobalt, and manganese is unsystematic and incomplete.

[0005] In order to reduce production costs, various lithium-containing wastewaters from industrial processes are often centrally treated and valuable metals such as lithium, phosphorus, nickel, cobalt, and manganese are recovered. How to quickly and efficiently recover and separate high-purity lithium phosphate has become an urgent problem to be solved in the industry. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a comprehensive recovery method for high-purity lithium phosphate and its application, to solve the problems of incomplete conversion, large amount of auxiliary materials introduced, high sodium content in the post-liquid, and low recovery rate of valuable metals in the high-purity lithium phosphate treatment process.

[0007] According to a first aspect of the present invention, a comprehensive method for the recovery of high-purity lithium phosphate is proposed, comprising the following steps:

[0008] S1: Prepare an acid-soluble bottom water solution with a pH of 1-2 by mixing ferric sulfate reagent with sulfuric acid;

[0009] S2: Mix the acid-soluble bottom water with high-purity lithium phosphate, add sulfuric acid to control the pH to 1-2.5, and obtain acid-soluble slurry;

[0010] S3: Add alkali to the acid-soluble slurry to control the pH to 4-4.5, and separate the solid and liquid to obtain phosphorus-iron slag and lithium-rich solution;

[0011] The high-heterogeneous lithium phosphate contains impurities of calcium, magnesium, aluminum, nickel, cobalt, and manganese.

[0012] In step S2, the purpose of adding sulfuric acid to control the pH below 2.5 is to ensure complete dissolution of lithium phosphate, reduce the lithium content in the subsequent impurity removal residue, and improve the lithium recovery rate. Controlling the pH above 1 can reduce the amount of acid used and avoid excessive use of auxiliary materials in subsequent processing.

[0013] In step S3, controlling the pH of the acid-soluble slurry to be between 4 and 4.5 is to ensure that the iron and aluminum in the high-heterogeneous lithium phosphate completely form phosphate precipitates while reducing the precipitation of nickel, cobalt, and manganese in the high-heterogeneous lithium phosphate, thereby ensuring that the obtained phosphorus-iron slag meets the standard for reuse in the acid soluble form of ferric phosphate.

[0014] Preferably, the main components of the high-heterophosphate lithium are: P 10%–18%, Fe 0.01%–3%, Li 5%–12%, Al 0.01%–3%, Ni 0.01%–4%, Co 0.01%–2%, Mn 0.01%–1%, Mg 0.01%–1%, Ca 1%–3%; and / or, the water content of the high-heterophosphate lithium is 20%–40%.

[0015] Preferably, the molar ratio of iron to phosphorus in the ferric sulfate reagent and the lithium heterophosphate to be treated is (1-1.3):1; and / or, the concentration of ferric sulfate in the acid-soluble bottom water is 0.17-0.37 mol / L.

[0016] Preferably, the ferric sulfate reagent is at least one of ferric sulfate or polyferric sulfate.

[0017] More preferably, the ferric sulfate reagent is selected from polyferric sulfate. In this invention, polyferric sulfate is used when preparing acid-soluble bottom water. Hydrolysis produces long-chain colloids with strong adsorption capacity. Compared to conventional ferric sulfate, it reacts faster with high-purity lithium phosphate and is also less expensive.

[0018] Preferably, in step S1, the temperature is controlled at 20-40°C during the preparation of the acid-soluble bottom water; and / or the concentration of the sulfuric acid is 1-3.7 mol / L.

[0019] Preferably, in step S2, the acid-soluble bottom water is mixed with high-purity lithium phosphate, and sulfuric acid is added to control the pH to 1-2 to obtain an acid-soluble slurry.

[0020] Preferably, in step S3, the temperature is controlled at 50–80°C when adding alkali to the acid-soluble slurry, and the reaction time is 1–5 hours. This process generates a large amount of ferric phosphate, and increasing the temperature can improve the reaction rate and filtration performance.

[0021] Preferably, the alkali is at least one of soda ash or sodium hydroxide.

[0022] Preferably, step S3 further includes washing the phosphorus-iron slag, during which sulfuric acid is added to control the pH at 3-4.

[0023] More preferably, the liquid-to-solid ratio of the ferrophosphorus slag washing process is (2-10) mL:1 g; after washing, solid-liquid separation is performed to obtain purified ferrophosphorus slag and wash water, and the wash water is returned to step S1 for the preparation of ferric sulfate solution. The reuse of the ferrophosphorus slag wash water can recover valuable metals, reduce the loss rate of valuable metals, and improve economic efficiency; the purified ferrophosphorus slag can be directly used as a raw material for the synthesis of ferrophosphorus.

[0024] Preferably, step S3 further includes removing impurities from the lithium-rich solution and then precipitating lithium to obtain lithium carbonate; the impurity removal involves adjusting the pH of the lithium-rich solution to 10.5-11 by adding alkali, and separating the solid and liquid phases to obtain nickel-cobalt-manganese slag and purified liquid. The nickel-cobalt-manganese slag can be sold or recycled after washing; while the lithium precipitation mother liquor can be reused by adding alkali.

[0025] Preferably, the purification temperature is controlled at 60–80°C, and the reaction time is 1–3 hours. Since hydroxides have poor filtration performance, increasing the temperature can improve their filtration performance.

[0026] Preferably, in the purified solution, Cu < 1 mg / L, Fe < 5 mg / L, and Al < 1 mg / L.

[0027] Preferably, the lithium-rich solution is further subjected to resin calcium and magnesium removal and carbon column oil removal treatment before impurity removal.

[0028] Traditional lithium phosphate treatment methods do not include processes for treating calcium and magnesium in lithium solutions, or they use ion exchange membranes. However, this invention uses resin to remove calcium and magnesium from lithium-rich solutions, which has a large processing capacity and lower cost. Furthermore, it employs a second stage of deep impurity removal to selectively separate high-value nickel, cobalt, and manganese metals from a large amount of phosphorus-iron slag, thereby improving the recovery rate of valuable metals.

[0029] More preferably, the resin used to remove calcium and magnesium is a chelating resin, which reduces the calcium content in the lithium-rich solution. 2+ <5mg / L; the carbon column degreasing uses high-quality coconut shell activated carbon of 20-80 mesh.

[0030] According to a second aspect of the present invention, a method for preparing a lithium-ion battery is provided, comprising the steps of the comprehensive recycling method as described in the first aspect of the present invention.

[0031] According to one embodiment of the present invention, at least the following beneficial effects are achieved:

[0032] This invention solves the problem of excessive sodium content in the solution after impurity removal by changing the acid dissolution method of high-purity lithium phosphate. At the same time, it reduces the amount of acid added and improves the recovery rate of precious metals, resulting in significant overall economic benefits.

[0033] Existing technologies for processing high-purity lithium phosphate have the following disadvantages:

[0034] (1) In the acid dissolution process of high-heterogeneous lithium phosphate, a large amount of acid needs to be added in order to ensure complete dissolution, which increases the cost;

[0035] (2) To ensure the complete reaction of phosphate, ferric sulfate is added after acid dissolution, which leads to a further decrease in pH.

[0036] (3) The acid added to dissolve the high-purity lithium phosphate needs to be neutralized and purified by adding alkali. This process will introduce a large number of sodium ions, which will affect the subsequent process of concentrating lithium-containing solution.

[0037] (4) The labor intensity of personnel is high, the operation cycle is long, the waiting time for materials is long, and the daily processing volume is low.

[0038] This invention utilizes the acidity of ferric sulfate reagent and the hydrogen ions generated from the hydrolysis of hydrogen phosphate (formed from phosphate ions contained in high-purity lithium phosphate) to acid-dissolve high-purity lithium phosphate, significantly reducing the amount of dilute sulfuric acid required for acid dissolution. Simultaneously, this process partially consumes the acid in the system, reducing the amount of alkali added in subsequent pH adjustment and impurity removal processes. Furthermore, the pH value of each step is controlled according to the type of impurity element to minimize interference from these elements. The subsequent impurity removal process produces less slag, directly converting the slag into valuable material without returning it to the leaching section, thus increasing the raw material throughput by 3%–5%. This comprehensive recovery method of the invention offers high impurity removal efficiency, low precious metal loss rate, low auxiliary material consumption, low waste generation, shorter operating cycle, and more economical equipment investment. Attached Figure Description

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0040] Figure 1 This is a process flow diagram of Embodiment 1 of the present invention. Detailed Implementation

[0041] The following will describe the concept and technical effects of the present invention clearly and completely with reference to the embodiments, so as to fully understand the purpose, features and effects of the present invention.

[0042] Unless otherwise specified, the raw materials, reagents or apparatus used in the following examples and comparative examples are available from conventional commercial sources or can be obtained by existing known methods.

[0043] Example 1

[0044] This embodiment provides a comprehensive recovery method for high-purity lithium phosphate. The wet high-purity lithium phosphate used has a moisture content of 27.34%, and its main impurities are as follows:

[0045] Al 0.0199%, Ni 1.7921%, Co 0.2325%, Mn 0.7467%, Mg 0.1943%, Ca2.0365%.

[0046] The comprehensive recycling method is as follows: Figure 1 As shown, it includes the following steps:

[0047] 1. Weigh 100g of polyferric sulfate (21% iron content) into a 2L beaker, add 1000ml of pure water, and gradually add 3.2mol / L dilute sulfuric acid while stirring, and monitor the pH change until pH=1.5.

[0048] 2. Weigh 52g of wet lithium phosphate material and add it to the above acid solution. While stirring, continue to monitor the pH change of the slurry. If pH > 2, continue to add 3.2mol / L dilute sulfuric acid to ensure that the pH of the slurry is 1-2. A total of 12mL of the dilute sulfuric acid is added in steps 1 and 2.

[0049] 3. Slowly add a 32% (w / w) alkali solution to the above slurry while stirring to adjust the pH to 4.0-4.5. Control the reaction temperature at 70℃ and the reaction time at 2 hours. After filtration, 193.3g of phosphorus-iron slag and 430mL of iron-removed liquid are obtained.

[0050] 4. Take 100g of ferric phosphate slag (wet slag), add 300mL of water at a liquid-to-solid ratio of 3:1, stir and wash, add 3.2mol / L dilute sulfuric acid to adjust the pH to 3.5, stir for 0.5h, and then filter to obtain wash water and washed slag. Return the wash water to step 1 for the preparation of ferric sulfate solution.

[0051] 5. Take the iron-removed liquid obtained in step 3, pass it through an 80-mesh coconut shell activated carbon column to remove oil, and chelate resin to remove calcium and magnesium. Then add 32% liquid alkali to adjust the pH to 10.5. The reaction time is 2 hours. After filtration, nickel-cobalt-manganese slag and deeply cleaned liquid are obtained.

[0052] 6. Add 70mL of pure water to a beaker, add 30g of soda ash, and keep the reaction temperature at 85℃ to obtain a lithium precipitation soda ash solution.

[0053] 7. After deep impurity removal, 300 mL of the solution is heated to 75°C and slowly added to the lithium-precipitating soda ash solution over a period of 3 hours. After addition, the reaction time is controlled at 1 hour, and the reaction temperature is maintained at 85°C. After filtration, washing, drying, and pulverization, battery-grade lithium carbonate is obtained.

[0054] Example 2

[0055] This embodiment provides a comprehensive recovery method for high-purity lithium phosphate. The wet high-purity lithium phosphate used has a moisture content of 27.34%, and its main impurities are as follows:

[0056] Al 0.0199%, Ni 1.7921%, Co 0.2325%, Mn 0.7467%, Mg 0.1943%, Ca2.0365%.

[0057] The comprehensive recycling method includes the following steps:

[0058] 1. Weigh 154g of polyferric sulfate (21% iron content) into a 2L beaker, add 800ml of pure water, and gradually add 3.2mol / L dilute sulfuric acid while stirring, and monitor the pH change until pH=1.5.

[0059] 2. Weigh 80g of the high-purity lithium phosphate wet material and add it to the above acid solution. While stirring, continue to monitor the pH change of the slurry. If pH > 2, continue to add 3.2mol / L dilute sulfuric acid to ensure that the pH of the slurry is 1-2. A total of 20mL of the dilute sulfuric acid is added in steps 1 and 2.

[0060] 3. Slowly add a 32% (w / w) alkali solution to the above slurry while stirring to adjust the pH to 4.0-4.5. Control the reaction temperature at 70℃ and the reaction time at 2 hours. After filtration, obtain 536.5g of phosphorus-iron slag and 460mL of iron-removed liquid.

[0061] 4. Take 100g of ferric phosphate slag (wet slag), add 300mL of water at a liquid-to-solid ratio of 3:1, stir and wash, add 3.2mol / L dilute sulfuric acid to adjust the pH to 3.5, stir for 0.5h, and then filter to obtain wash water and washed slag. Return the wash water to step 1 for the preparation of ferric sulfate solution.

[0062] 5. Take the iron-removed liquid obtained in step 3, pass it through an 80-mesh coconut shell activated carbon column to remove oil, and chelate resin to remove calcium and magnesium. Then add 32% liquid alkali to adjust the pH to 10.5. The reaction time is 2 hours. After filtration, nickel-cobalt-manganese slag and deeply cleaned liquid are obtained.

[0063] 6. Add 70mL of pure water to a beaker, add 30g of soda ash, and keep the reaction temperature at 85℃ to obtain a lithium precipitation soda ash solution.

[0064] 7. After deep impurity removal, 300 mL of the solution is heated to 75°C and slowly added to the lithium-precipitating soda ash solution over a period of 3 hours. After addition, the reaction time is controlled at 1 hour, and the reaction temperature is maintained at 85°C. After filtration, washing, drying, and pulverization, battery-grade lithium carbonate is obtained.

[0065] Comparative Example 1

[0066] This comparative example provides a method for recovering high-purity lithium phosphate. The wet high-purity lithium phosphate used has a moisture content of 27.34%, and the main impurities are as follows:

[0067] The comprehensive recovery method comprising the following steps includes: Al 0.0199%, Ni 1.7921%, Co 0.2325%, Mn 0.7467%, Mg 0.1943%, Ca 2.0365%.

[0068] 1. Weigh 80g of wet high-purity lithium phosphate material into a 2L beaker, add 800ml of pure water, and gradually add 141ml of 3.2mol / L dilute sulfuric acid while stirring, and monitor the pH change until pH=1.5.

[0069] 2. Weigh 154g of polyferric sulfate (iron content 21%) and add it to the above acid solution.

[0070] 3. Slowly add a 32% (w / w) liquid alkali solution to the above slurry while stirring to adjust the pH to 4.0-4.5. Control the reaction temperature at 70℃ and the reaction time at 2 hours. After filtration, obtain 470g of phosphorus-iron wet slag and 400mL of iron-removed liquid.

[0071] 4. Take 100g of phosphorus iron slag (wet slag), add 300mL of water at a liquid-solid ratio of 3:1 and stir and wash. Add 3.2mol / L dilute sulfuric acid to adjust the pH to 3.5. After stirring for 0.5h, filter to obtain washing water and washed slag.

[0072] Comparative Example 2

[0073] This comparative example provides a method for recovering high-purity lithium phosphate. The wet high-purity lithium phosphate used has a moisture content of 27.34%, and the main impurities are as follows:

[0074] The comprehensive recovery method comprising the following steps includes: Al 0.0199%, Ni 1.7921%, Co 0.2325%, Mn 0.7467%, Mg 0.1943%, Ca 2.0365%.

[0075] 1. Weigh 80g of wet high-purity lithium phosphate material into a 2L beaker, add 800ml of pure water, and gradually add 130.2ml of 3.2mol / L dilute sulfuric acid while stirring, and monitor the pH change until pH=1.9.

[0076] 2. Weigh 130g of polyferric sulfate (iron content 21%) and add it to the above acid solution. Continue to monitor the pH change of the slurry while stirring.

[0077] 3. Slowly add a 32% (w / w) alkali solution to the above slurry while stirring to adjust the pH to 4.0-4.5. Control the reaction temperature at 70℃ and the reaction time at 2 hours. After filtration, obtain 450g of phosphorus-iron wet slag and 400mL of iron-removed liquid.

[0078] 4. Take 100g of phosphorus iron slag (wet slag), add 300mL of water at a liquid-solid ratio of 3:1 and stir and wash. Add 3.2mol / L dilute sulfuric acid to adjust the pH to 3.5. After stirring for 0.5h, filter to obtain washing water and washed slag.

[0079] Comparative Example 3

[0080] This comparative example provides a method for recovering high-purity lithium phosphate. The wet high-purity lithium phosphate used has a moisture content of 27.34%, and the main impurities are as follows:

[0081] Al 0.0199%, Ni 1.7921%, Co 0.2325%, Mn 0.7467%, Mg 0.1943%, Ca2.0365%

[0082] The comprehensive recycling method includes the following steps:

[0083] 1. Weigh 80g of wet high-purity lithium phosphate material into a 2L beaker, add 800ml of pure water, and gradually add 20ml of 3.2mol / L dilute sulfuric acid while stirring. The pH at this time is 7.2.

[0084] 2. Weigh 154g of polyferric sulfate (iron content 21%) and add it to the above solution. Continue to monitor the pH change of the slurry while stirring.

[0085] 3. Slowly add a 32% (w / w) alkali solution to the above slurry while stirring to adjust the pH to 4.0-4.5. Control the reaction temperature at 70℃ and the reaction time at 2 hours. After filtration, obtain 478g of phosphorus-iron wet slag and 420mL of iron-removed liquid.

[0086] 4. Take 100g of phosphorus iron slag (wet slag), add 300mL of water at a liquid-solid ratio of 3:1 and stir and wash. Add 3.2mol / L dilute sulfuric acid to adjust the pH to 3.5. After stirring for 0.5h, filter to obtain washing water and washed slag.

[0087] In step 1 of this comparative example, the amount of dilute sulfuric acid used was the same as in Example 2, which failed to effectively dissolve lithium. Even after adding an equal amount of polyferric sulfate in step 2 as in Example 2, the lithium content in the resulting ferrophosphate wet slag was still higher than 0.2% (possibly due to the complex hydrolysis reaction of phosphate). Continuing to add acid for acid washing to recover lithium from the ferrophosphate slag would increase recovery costs and result in the loss of ferrophosphate in the slag, reducing its recovery value. Simultaneously, the decrease in pH and the increase in impurities such as ferrophosphate in the acid washing water would lead to an increase in the amount of polyferric sulfate added during the recycling process, resulting in an increase in the amount of ferrophosphate slag, reducing the recovery rate of valuable metals, and increasing the conversion cost of high-purity lithium phosphate.

[0088] Test case

[0089] The composition of the iron-removed liquid and the washing residue (phosphorus iron slag) obtained in Examples 1-2 and Comparative Examples 1-3 were tested respectively, and the test results are shown in Table 1.

[0090] Table 1. Composition and content of iron-removed liquid and ferrophosphate slag

[0091]

[0092]

[0093] As can be seen from Table 1, the sodium content of the iron-removed liquids of Examples 1-2 and Comparative Examples 1-2 differs greatly, indicating that the traditional method of acid dissolving lithium phosphate followed by impurity removal consumes a large amount of alkali. The extremely high sodium content necessitates the addition of an extra impurity removal process for subsequent lithium carbonate preparation, thereby increasing the production cost of lithium carbonate.

[0094] The composition of the nickel-cobalt-manganese slag and the liquid after deep impurity removal obtained in steps (5) of Examples 1-2 were tested respectively. The test results are shown in Table 2. The content of elements with extremely low content or undetected content is considered to be 0.1 mg / L.

[0095] Table 2. Nickel-cobalt-manganese slag obtained after deep impurity removal and composition of the liquid after deep impurity removal.

[0096]

[0097] As can be seen from Table 2, the content of impurities such as Mg, Ca, Fe, and P in the deep impurity removal solution prepared by Examples 1 and 2 of the present invention is all <1 mg / L, which meets the index for preparing battery-grade lithium carbonate. The lithium carbonate prepared using it meets the quality requirements for battery-grade lithium carbonate.

[0098] Examples 1 and 2 used a pre-prepared acid-soluble bottom water method. Compared with Comparative Examples 1 and 2, the sodium content in the liquid after iron removal was reduced by more than 60%; the removal rates of Fe, Al, Ni, Co, Mn, and Ca all reached more than 99%; the Li content in the slag after washing was less than 0.1%; and the recovery rate of valuable metals was greater than 99%.

[0099] It should be noted that the data of the iron-removed liquids in Examples 1 and 2 in Table 2 are from retesting, so the content of some elements may differ from that in Table 1. Since the recovery value of elements such as Fe and Cu in the nickel-cobalt-manganese slag is low, they were not tested.

[0100] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A comprehensive method for the recovery of high-purity lithium phosphate, characterized in that, Includes the following steps: S1: Prepare an acid-soluble bottom water solution with a pH of 1-2 by mixing ferric sulfate reagent with sulfuric acid; S2: Mix the acid-soluble bottom water with high-purity lithium phosphate, add sulfuric acid to control the pH to 1~2.5, and obtain acid-soluble slurry; S3: Add alkali to the acid-soluble slurry to control the pH to 4~4.5, and separate the solid and liquid to obtain phosphorus iron slag and lithium-rich solution; The high-purity lithium phosphate contains impurity elements such as calcium, magnesium, aluminum, nickel, cobalt, and manganese. The ferric sulfate reagent is polyferric sulfate.

2. The comprehensive recycling method according to claim 1, characterized in that, The main components of the high-heterophosphate lithium are: P 10%~18%, Fe 0.01%~3%, Li 5%~12%, Al 0.01%~3%, Ni 0.01%~4%, Co 0.01%~2%, Mn 0.01%~1%, Mg 0.01%~1%, Ca 1%~3%; and / or, the water content of the high-heterophosphate lithium is 20%-40%.

3. The comprehensive recycling method according to claim 1, characterized in that, The molar ratio of iron to phosphorus in the ferric sulfate reagent and the lithium heterophosphate to be treated is (1~1.3):1; and / or the concentration of ferric sulfate in the acid-soluble bottom water is 0.17~0.37 mol / L.

4. The comprehensive recycling method according to claim 1, characterized in that, In step S3, when adding alkaline solution to the acid-soluble slurry, the temperature is controlled at 50~80℃ and the reaction time is 1~5h.

5. The comprehensive recycling method according to claim 1, characterized in that, Step S3 also includes washing the phosphorus-iron slag with sulfuric acid during the washing process to control the pH at 3-4.

6. The comprehensive recycling method according to claim 1, characterized in that, Step S3 further includes removing impurities from the lithium-rich solution and then precipitating lithium to obtain lithium carbonate; the impurity removal involves adjusting the pH of the lithium-rich solution to 10.5-11 by adding alkali, and then separating the solid and liquid to obtain nickel-cobalt-manganese slag and purified liquid.

7. The comprehensive recycling method according to claim 6, characterized in that, The purification temperature is controlled at 60~80℃, and the reaction time is 1~3h.

8. The comprehensive recycling method according to claim 6, characterized in that, In the purified solution, Cu < 1 mg / L, Fe < 5 mg / L, and Al < 1 mg / L.

9. The comprehensive recycling method according to claim 6, characterized in that, Before impurity removal, the lithium-rich solution undergoes resin calcium and magnesium removal and carbon column oil removal treatment.

10. A method for preparing a lithium-ion battery, characterized in that, Includes the steps of the integrated recycling method according to any one of claims 1-9.

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