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CN-116924368-B - Method for extracting ferric phosphate from waste residue after extracting lithium from lithium iron phosphate

CN116924368BCN 116924368 BCN116924368 BCN 116924368BCN-116924368-B

Abstract

The invention provides a method for extracting ferric phosphate from waste residues after lithium iron phosphate extraction, which belongs to the field of new energy battery recovery, and aims to ensure that the efficiency in the extraction process is higher by accurately detecting iron and phosphorus elements in the waste residues after lithium iron phosphate extraction, the impurities such as aluminum ions and the like are taken away by magnetic substances by adsorbing the magnetic substances on the magnetic substances, so that the subsequent extraction process is more effective, the iron phosphate extraction is more effective by adding a chelating agent in a higher-performance extraction mode, and the 'three-high' recovery treatment of high efficiency, high value and high purification of the iron phosphate residues in the waste residues after lithium iron phosphate extraction is realized by the three steps.

Inventors

  • QU MINGYANG

Assignees

  • 北京荣田储能科技有限公司

Dates

Publication Date
20260505
Application Date
20230801

Claims (8)

  1. 1. A method for extracting ferric phosphate from waste residue after lithium iron phosphate is extracted is characterized in that firstly, the waste residue after lithium iron phosphate is extracted is subjected to primary selection through a magnetic separation step, and then a battery-grade anhydrous ferric phosphate product is obtained through a refining step, and the method comprises the following specific steps: s21, drying and crushing waste residues after lithium iron phosphate is extracted, grinding the waste residues by an oval ball mill, and sieving the waste residues by a 200-220-mesh sieve to obtain waste residue powder after lithium iron phosphate extraction with the granularity of 0.065-0.074 mm; s22, conveying the waste residue powder after lithium iron phosphate is extracted into a magnetic separator through a conveyor belt for magnetic separation, and setting the magnetic flux density of the magnetic separator to 9000-10000Gs; s23, repeating the step S22 for 4-5 times to obtain primary iron phosphate refined powder C; S31, mixing the iron phosphate refined powder C initially selected in the S23 and ammonia water with the concentration of 20% according to the mass percentage of 1:3 to form slurry; s32, adding a chelating agent into the slurry, mixing and adding the mixture into a reaction kettle, wherein the chelating agent and the primary iron phosphate refined powder C are proportioned according to the mass percentage of 0.05:1; S33, stirring at the temperature of 80-90 ℃ at the speed of 200-400r/min for 2-3 hours, and immediately filtering after the reaction is finished to obtain ammonium phosphate filtrate and ferric hydroxide filter residues; S34, cooling the ammonium phosphate filtrate in the S33 at room temperature, placing the ferric hydroxide filter residues in a drying box, and keeping the temperature of 40-80 ℃ for 2-3 hours; s35, placing the dried ferric hydroxide filter residues and a sulfuric acid solution with the concentration of 45% into a container according to the mass percentage of 1:4, and stirring at the room temperature of 25-30 ℃ for 1-2 hours at the speed of 600 r/min; S36, adding polyvinylpyrrolidone as a dispersing agent, wherein the mass ratio of the dispersing agent to the added ferric hydroxide filter residue is 1:20, continuously stirring for 30 minutes in an inert gas atmosphere at the temperature of 60 ℃ at the same time, and dropwise adding the ammonium phosphate filtrate cooled in the step S34 while stirring; S37, continuously stirring for 4-5 hours at the temperature of 50-60 ℃, cooling to room temperature, and filtering to obtain filtrate containing ammonium sulfate and ferric phosphate dihydrate filter residues; S38, washing the filter residue of the ferric phosphate dihydrate with absolute ethyl alcohol for 2-3 times, washing with distilled water for 3-4 times, and drying in a drying oven at 110-170 ℃ for 8-10 hours to obtain pure ferric phosphate dihydrate; And S39, calcining the ferric phosphate dihydrate in an inert gas atmosphere at the temperature of 600 ℃ for 1-2 hours to obtain a battery-grade anhydrous ferric phosphate product.
  2. 2. The method for extracting ferric phosphate from waste residue after lithium iron phosphate extraction according to claim 1, wherein the method further comprises the step of detecting the content of iron and phosphorus in the waste residue after lithium iron phosphate extraction before the magnetic separation step, specifically comprising the steps of: s10, taking 100 g of waste residues after lithium extraction of lithium iron phosphate to be detected, grinding the waste residues into powder A, and controlling the granularity of the powder A to be 300-325 meshes; S11, adding the powder A into a wide-mouth polypropylene bottle with the capacity of 250 ml; S12, adding 100ml of ethanol, and placing the mixture into an ultrasonic cleaner to clean for 20-30 seconds for 2-3 times; s13, adding 150ml of weakly acidic ionized water with the pH value of 6.6-6.9, placing into an ultrasonic cleaner for cleaning for 30 seconds, lasting for 4-5 times, and filtering out water to obtain powder B; S14, adding 10ml of aqua regia into a wide-mouth polypropylene bottle filled with the powder B to form a solution, and injecting pure water to a 200ml scale; s15, heating the solution to 80-90 ℃ and keeping the temperature for 10-20 minutes; S16, cooling the solution to the room temperature of 25-27 ℃ and injecting pure water to a 200ml scale; s17, detecting the content of iron and phosphorus in the solution by using an ICP-MS detection method.
  3. 3. The method for extracting ferric phosphate from waste residues after lithium iron phosphate extraction according to claim 2, wherein the waste residues after lithium iron phosphate extraction with more than 20 mass percent and more than 10 mass percent of iron content detected by an ICP-MS detection method are used as raw materials for extracting ferric phosphate.
  4. 4. The method for extracting iron phosphate from waste residue after lithium iron phosphate extraction according to claim 1, wherein in step S32, the chelating agent is at least one selected from hydroxyethylidene diphosphonic acid, 2-phosphonate butane-1, 2, 4-tricarboxylic acid, and 2-hydroxyphosphonoacetic acid.
  5. 5. The method for extracting iron phosphate from waste residue after lithium extraction from lithium iron phosphate according to claim 1, wherein in S33, the iron hydroxide residue exists in the form of Fe 2 O 3 .3H 2 O.
  6. 6. The method for extracting iron phosphate from waste residue after lithium iron phosphate extraction according to claim 1, wherein the polyvinylpyrrolidone added in S36 is one or more of PVP-K15, PVP-K30, PVP-K60 and PVPK 90.
  7. 7. A method for extracting ferric phosphate from waste residue after lithium iron phosphate is extracted is characterized in that firstly, the waste residue after lithium iron phosphate is extracted is subjected to primary selection through a magnetic separation step, and then, a battery-grade anhydrous ferric phosphate product is obtained through a refining step, and the method is specifically as follows: s21, drying and crushing waste residues after lithium iron phosphate is extracted, grinding the waste residues by an oval ball mill, and sieving the waste residues by a 200-220-mesh sieve to obtain waste residue powder after lithium iron phosphate extraction with the granularity of 0.065-0.074 mm; s22, conveying the waste residue powder after lithium iron phosphate is extracted into a magnetic separator through a conveyor belt for magnetic separation, and setting the magnetic flux density of the magnetic separator to 9000-10000Gs; s23, repeating the step S22 for 4-5 times to obtain primary iron phosphate refined powder C; S31', mixing the primary selected iron phosphate refined powder C and water according to the mass percentage of 1:10, adding the mixture into a reaction kettle, continuously heating the mixture, stirring the mixture at the temperature of 80-90 ℃ at the speed of 200-400r/min for 2-3 hours, filtering the mixture to obtain filter residue D and a solution of iron dissolved in heat Shui Linsuan, cooling the filter residue D to room temperature, precipitating the filter residue D and the solution of iron dissolved in heat Shui Linsuan, and filtering the solution to obtain a solid product E1 of ferric phosphate dihydrate and a filtrate F1 of ferric phosphate; s32', mixing the filter residue D and 30% hydrogen peroxide according to the mass percentage of 1:3, heating to 50 ℃ at the speed of 8 ℃ per minute, fully stirring, preserving heat for 1 hour, and filtering to obtain a ferric phosphate dihydrate solid product E2 and a filtrate F2; s33', washing the solid ferric phosphate dihydrate E1 and the solid ferric phosphate dihydrate E2 for 3-4 times by using distilled water, and drying in a drying oven at 110-170 ℃ for 8-10 hours to obtain pure ferric phosphate dihydrate; And S34', calcining the ferric phosphate dihydrate at the temperature of 600 ℃ for 1-2 hours to obtain a battery-grade anhydrous ferric phosphate product.
  8. 8. The method for extracting ferric phosphate from waste residue after lithium iron phosphate extraction according to claim 7, further comprising the step of detecting the content of iron and phosphorus in the waste residue after lithium iron phosphate extraction, specifically: s10, taking 100 g of waste residues after lithium extraction of lithium iron phosphate to be detected, grinding the waste residues into powder A, and controlling the granularity of the powder A to be 300-325 meshes; S11, adding the powder A into a wide-mouth polypropylene bottle with the capacity of 250 ml; S12, adding 100ml of ethanol, and placing the mixture into an ultrasonic cleaner to clean for 20-30 seconds for 2-3 times; s13, adding 150ml of weakly acidic ionized water with the pH value of 6.6-6.9, placing into an ultrasonic cleaner for cleaning for 30 seconds, lasting for 4-5 times, and filtering out water to obtain powder B; S14, adding 10ml of aqua regia into a wide-mouth polypropylene bottle filled with the powder B to form a solution, and injecting pure water to a 200ml scale; s15, heating the solution to 80-90 ℃ and keeping the temperature for 10-20 minutes; S16, cooling the solution to the room temperature of 25-27 ℃ and injecting pure water to a 200ml scale; s17, detecting the content of iron and phosphorus in the solution by using an ICP-MS detection method.

Description

Method for extracting ferric phosphate from waste residue after extracting lithium from lithium iron phosphate Technical Field The invention relates to the field of new energy battery recovery, in particular to a method for refining ferric phosphate from waste residues after lithium extraction of lithium iron phosphate. Background In recent years, with the rapid development of the global electric automobile industry and the energy storage industry, the lithium iron phosphate battery is more widely popularized and applied due to the advantages of high specific capacity, stable structure, safe performance, long service life and the like. Meanwhile, according to the current life cycle of the lithium ion battery is generally 3-5 years, the problem of scrapping a large amount of lithium iron phosphate batteries is solved, and according to the estimated 2023 years later, the scrapping amount of the power battery in China reaches 12-17 ten thousand tons, and the large amount of lithium iron phosphate batteries need to be recycled. At present, waste lithium iron phosphate is mainly treated by a wet process, and the main procedures comprise discharging, disassembling, crushing and sorting the battery to obtain black powder, and then, recovering and reutilizing valuable elements through operations such as leaching, element separation and purification, product regeneration and the like. The recovery value of lithium is high, and the process for recovering lithium in the waste lithium iron phosphate into high-value lithium carbonate or lithium hydroxide products is also mature. Part of the waste residues after lithium iron phosphate is extracted contains a large amount of valuable reusable iron elements, and can be reprocessed to produce ferric phosphate, but the waste residues also contain impurities such as aluminum, and the like, and the existing aluminum removal process of the ferric phosphate has the problems of long process, poor deep aluminum removal impurity removal effect, low product purity and yield and the like. How to carry out high-efficiency, high-value and high-purification 'three-high' recovery treatment on the iron phosphate slag is an important difficult problem facing the recovery of the waste lithium iron phosphate battery at present. Disclosure of Invention In order to solve the technical problems, the invention provides a method for extracting ferric phosphate from waste residues after lithium iron phosphate extraction, which is mainly divided into three steps of detection, magnetic separation and extraction of the waste residues after lithium iron phosphate extraction, and can realize the technical effects of high-efficiency, high-value and high-purification 'three-high' recovery treatment of the ferric phosphate residues in the waste residues after lithium iron phosphate extraction. The method for extracting ferric phosphate from the waste residue after lithium iron phosphate extraction has the advantages that the efficiency in the extraction process is higher through the accurate detection of iron and phosphorus elements in the waste residue after lithium iron phosphate extraction, the impurities such as aluminum ions are taken away by the magnetic substances through the adsorption of the magnetic substances to the magnetic lifting, the impurities such as aluminum in the waste residue after lithium iron phosphate extraction are removed, the subsequent extraction process is more effective, the ferric phosphate extraction is higher through a higher-performance extraction mode of adding a chelating agent, and the 'three-high' recovery treatment of high efficiency, high value and high purification of the ferric phosphate residue in the waste residue after lithium iron phosphate extraction is realized through the three steps. The invention also provides a technical scheme of a more environment-friendly refining mode, thereby ensuring that an alternative scheme is provided under the condition of high environment-friendly requirement. Specifically, the technical scheme of the invention provides a method for extracting ferric phosphate from waste residues after lithium iron phosphate is extracted, which is characterized in that firstly, the waste residues after lithium iron phosphate is extracted are subjected to primary selection through a magnetic separation step, and then, a battery-grade anhydrous ferric phosphate product is obtained through a refining step, and the method comprises the following specific steps: s21, drying and crushing waste residues after lithium iron phosphate is extracted, grinding the waste residues by an oval ball mill, and sieving the waste residues by a 200-220-mesh sieve to obtain waste residue powder after lithium iron phosphate extraction with the granularity of 0.065-0.074 mm; S22, conveying the waste residue powder after lithium iron phosphate is extracted into a magnetic separator through a conveyor belt for magnetic separation, and setting the magnetic flux density