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CN-118019707-B - Method for removing aluminum from directional circulating lithium iron phosphate waste

CN118019707BCN 118019707 BCN118019707 BCN 118019707BCN-118019707-B

Abstract

The application provides a method for removing aluminum from directional circulating lithium iron phosphate waste, which comprises the following steps of (1) mixing lithium iron phosphate waste, ferric salt solution and reducing agent for pulping, carrying out one-step reaction to obtain mixed salt solution containing aluminum ions and ferrous ions and lithium iron phosphate after aluminum removal, (2) regulating the pH value of the mixed salt solution obtained in the step (1), carrying out two-step reaction, carrying out solid-liquid separation to obtain aluminum hydroxide slag and ferrous solution, and (3) mixing the ferrous solution obtained in the step (2) with an oxidizing agent, regulating the pH value, and carrying out three-step reaction to obtain ferric salt solution, wherein the ferric salt solution is used for recycling the ferric salt solution obtained in the step (1). The aluminum removal method disclosed by the application does not introduce other impurities during leaching, is simple to operate, free of pollution, capable of recycling the impurity removing agent, capable of recycling iron, low in process cost and good in impurity removing effect.

Inventors

  • XU JIQI
  • LI CHANGDONG
  • RUAN DINGSHAN
  • CHEN RUOKUI
  • DUAN JINLIANG
  • XIA YANG

Assignees

  • 广东邦普循环科技有限公司
  • 湖南邦普循环科技有限公司

Dates

Publication Date
20260505
Application Date
20240104

Claims (19)

  1. 1. A method for removing aluminum from directional circulating lithium iron phosphate waste, comprising the steps of: (1) Mixing lithium iron phosphate waste, ferric salt solution and reducing agent for pulping, and obtaining mixed salt solution containing aluminum ions and ferrous ions and lithium iron phosphate after aluminum removal through one-step reaction, wherein the potential of the one-step reaction is-2.0 to-1.0V; (2) Regulating the pH value of the mixed salt solution obtained in the step (1), and carrying out solid-liquid separation after the two-step reaction to obtain aluminum hydroxide slag and ferrous solution; (3) Mixing the ferrous solution obtained in the step (2) with an oxidant, regulating the pH value, and carrying out three-step reaction to obtain an iron salt solution, wherein the iron salt solution is used for recycling the iron salt solution obtained in the step (1).
  2. 2. The method of claim 1, wherein the iron salt solution of step (1) comprises any one or a combination of at least two of an iron sulfate solution, an iron chloride solution, or an iron nitrate solution.
  3. 3. The method of claim 1, wherein the ferric ion concentration in the ferric salt solution is 2-20 g/L.
  4. 4. The method of claim 1, wherein the reducing agent comprises any one or a combination of at least two of ferrous sulfate, ferrous nitrate, or ferrous chloride.
  5. 5. The method of claim 1, wherein the lithium iron phosphate waste slurry in step (1) has a liquid to solid ratio of (2-10) of 1 mL/g.
  6. 6. The method of claim 1, wherein the temperature of the one-step reaction is 30-80 ℃.
  7. 7. The method of claim 1, wherein the one-step reaction is performed for a period of 2 to 8 hours.
  8. 8. The method of claim 1, wherein the pH of the one-step reaction is 2 to 4.
  9. 9. The method of claim 1, wherein the pH adjuster of step (2) comprises any one or a combination of at least two of sodium hydroxide, sodium carbonate, or aqueous ammonia.
  10. 10. The method of claim 1, wherein the pH in step (2) is 3.5 to 5.5.
  11. 11. The method of claim 1, wherein the temperature of the two-step reaction of step (2) is 30-90 ℃.
  12. 12. The method of claim 1, wherein the two-step reaction of step (2) takes 3 to 10 hours.
  13. 13. The method of claim 1, wherein the oxidizing agent of step (3) comprises any one or a combination of at least two of hydrogen peroxide, oxygen, or hypochlorous acid.
  14. 14. The method of claim 1, wherein the molar ratio of ferrous ions in the oxidant and ferrous-containing solution of step (3) is (1-5): 1.
  15. 15. The method of claim 1, wherein the pH adjuster of step (3) comprises any one or a combination of at least two of sulfuric acid, nitric acid, or hydrochloric acid.
  16. 16. The method of claim 1, wherein the pH in step (3) is 0.1 to 2.
  17. 17. The method of claim 1, wherein the temperature of the three-step reaction of step (3) is 20-60 ℃.
  18. 18. The method of claim 1, wherein the three-step reaction is performed for a period of 0.5 to 3 hours.
  19. 19. The method of claim 1, comprising the steps of: (1) Mixing lithium iron phosphate waste, ferric salt solution with the iron concentration of 2-20 g/L and reducing agent according to the liquid-solid ratio of (2-10): 1, pulping, and reacting for 2-8 hours at the electric potential of-2.0 to-1.0V and the temperature of 30-80 ℃ to obtain mixed salt solution containing aluminum ions and ferrous ions and lithium iron phosphate after aluminum removal; (2) Adding alkali to adjust the pH value of the mixed salt solution obtained in the step (1) to be 3.5-5.5, reacting for 3-10 hours at the temperature of 30-90 ℃, and carrying out solid-liquid separation to obtain aluminum hydroxide slag and ferrous solution; (3) Mixing the ferrous solution obtained in the step (2) with an oxidant according to the molar ratio of 1 (1-5), adding acid to adjust the pH value to 0.1-2, and reacting at 20-60 ℃ for 0.5-3 h to obtain an iron salt solution, wherein the iron salt solution is used for recycling the iron salt solution in the step (1).

Description

Method for removing aluminum from directional circulating lithium iron phosphate waste Technical Field The application relates to the technical field of resource recovery, in particular to a method for removing aluminum from directional circulating lithium iron phosphate waste. Background The lithium ion batteries are taken as main products of the battery market, the yield is increasing year by year, meanwhile, the number of the abandoned lithium ion batteries is very huge, the new energy automobiles in China are expected to continue to develop rapidly, the demand of the lithium ion batteries is expanded, so that the abandoned lithium ion batteries are gradually increased, and the fact that a large number of abandoned lithium iron phosphate batteries are included indicates that the lithium iron phosphate batteries in the abandoned batteries in the future are dominant, so that the recycling of the abandoned lithium iron phosphate batteries is indistinct, the recycling of the abandoned lithium iron phosphate batteries is beneficial to protecting the environment, and the sustainable development of the lithium battery industry in China is also beneficial. The current method for treating waste lithium iron phosphate powder mainly comprises a wet method and a fire method, wherein the wet method is divided into wet method full-component leaching and wet method selective lithium leaching, the wet method full-component treatment method is to recycle the full components of the waste lithium iron phosphate powder, remove impurities after all the component elements in the waste materials are dissolved, and the wet method selective lithium leaching is to leach the lithium into the solution so as to separate the lithium iron phosphate powder from the elements such as ferrophosphorus. CN114784405A discloses a method for recycling aluminum from waste lithium iron phosphate batteries, which comprises the steps of sequentially carrying out aluminum removal reaction, solid-liquid separation, i times of washing and leaching treatment on positive electrode material powder of the waste lithium iron phosphate batteries, wherein j times of washing adopts j+1th washing liquid obtained after j+1th washing in the previous batch, i times of washing adopts pure water, wherein i is more than or equal to 2 and less than or equal to 6, and j is more than or equal to 1. CN116199201a discloses a method for removing aluminum from waste lithium iron phosphate pole piece powder and comprehensively recovering the same, belonging to the technical field of resource recovery and utilization; the method comprises the following steps of 1, leaching lithium, iron, phosphorus and other impurity elements from waste lithium iron pole piece black powder by using hydrochloric acid with a certain concentration and an oxidant, 2, adding an extractant into the solution, extracting ferric iron from an aqueous solution into an organic phase, 3, adjusting the pH value of the aqueous phase after shaking separation to enable aluminum element to be precipitated in the form of aluminum hydroxide, and filtering the aluminum phase, 4, mixing the inorganic phase and the organic phase again, adjusting the pH value to obtain ferric phosphate precipitation, filtering the ferric phosphate precipitation, 5, adjusting the pH value of filtrate after filtering, and adding phosphate to obtain lithium phosphate. The aluminum removal method is easy to cause other element loss in the aluminum removal process, and is easy to introduce impurity elements, so that the impurity removal cost is increased. Disclosure of Invention The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims. The application provides a method for removing aluminum from directional circulating lithium iron phosphate waste, which is free from introducing other impurities during leaching, simple to operate, free from pollution, recyclable in impurity removing agent, low in process cost and good in impurity removing effect, and iron element can be recycled. In a first aspect, the present application provides a method for removing aluminium from directional circulating lithium iron phosphate waste, the method comprising the steps of: (1) Mixing lithium iron phosphate waste, ferric salt solution and reducing agent for pulping, and obtaining mixed salt solution containing aluminum ions and ferrous ions and lithium iron phosphate after aluminum removal through one-step reaction; (2) Regulating the pH value of the mixed salt solution obtained in the step (1), and carrying out solid-liquid separation after the two-step reaction to obtain aluminum hydroxide slag and ferrous solution; (3) Mixing the ferrous solution obtained in the step (2) with an oxidant, regulating the pH value, and carrying out three-step reaction to obtain an iron salt solution, wherein the iron salt solution is used for recycling the iron salt solution obtained in the