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Method for treating high-impurity lithium iron phosphate waste powder by using low-consumption phosphoric acid

A technology for the treatment of lithium iron phosphate and phosphoric acid, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve the problem that battery-grade iron phosphate cannot be directly recovered, the purity of iron phosphate is not high, and the ratio of iron to phosphorus cannot be guaranteed, etc. problem, to achieve good aluminum removal effect, avoid structure damage, and achieve the effect of pollution-free recycling

Pending Publication Date: 2022-01-04
ZHUZHOU SMELTER GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Such as CN108110357A has announced a kind of method that utilizes dilute acid to process lithium iron phosphate, but the treatment of dilute acid is only suitable for handling the lithium iron phosphate of low impurity content, for high impurity lithium iron phosphate waste powder, the content of impurity can be greatly limited Lithium leaching
Just as CN106910959A discloses a method for selectively reclaiming lithium from lithium iron phosphate waste by direct oxidation, although the leaching rate of lithium is high, the pH of the system is too high when most oxidants are directly selectively leached, and the protonation of the solvent is serious , leading to the formation of iron phosphate is not high purity
[0004] To sum up, most of the existing recycling technologies have problems such as difficult process control, large amount of acid and alkali, and large waste water output, which cannot be directly recycled to obtain battery-grade iron phosphate, or the purity of the obtained iron phosphate is not high, and the iron-to-phosphorus ratio cannot be guaranteed.

Method used

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  • Method for treating high-impurity lithium iron phosphate waste powder by using low-consumption phosphoric acid
  • Method for treating high-impurity lithium iron phosphate waste powder by using low-consumption phosphoric acid
  • Method for treating high-impurity lithium iron phosphate waste powder by using low-consumption phosphoric acid

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Embodiment 1

[0049] A method for treating high-heterotype lithium iron phosphate waste powder with low-consumption phosphoric acid, the process flow is as follows figure 1 shown, including the following steps:

[0050] The disassembled high-heterolithium iron phosphate waste powder (mass percentage content of impurities C, Cu, and Al is 6.21%, 0.07% and 1.85% respectively, and contains a small amount of PVDF and diaphragm) is calcined at 550°C in an argon atmosphere 6h, to fully decompose the binder PVDF and the diaphragm. Slurry the waste powder from the removal of PVDF and diaphragm with ultrapure water at a solid-to-liquid ratio of 1:3, and use energy to convert Al into AlO 2- 1.2 times the theoretical molar amount of LiOH to remove aluminum, the concentration of LiOH in the system is 0.5mol / L, the reaction time is 0.5h, and filtered after the reaction. The carbon of the filtrate is precipitated into aluminum, and after the filter residue is dried, continue to mix the slurry with ultr...

Embodiment 2

[0052] A method for treating high-hetero-hetero lithium iron phosphate waste powder with low consumption of phosphoric acid, comprising the following steps:

[0053] The dismantled high-heterolithium iron phosphate waste powder (mass percentages of impurities C, Cu, and Al are 5.27%, 0.02%, and 1.06% respectively, and contains a small amount of PVDF) is calcined at 550°C for 6 hours in an argon atmosphere. Fully decompose the binder PVDF. Slurry the waste powder after removing PVDF with ultrapure water at a solid-to-liquid ratio of 1:3, and use energy to convert Al into AlO 2- 1.3 times the theoretical molar amount of LiOH to remove aluminum, the concentration of LiOH in the system is 0.6mol / L, the reaction time is 0.5h, and filter after the reaction. The carbon of the filtrate is precipitated into aluminum, and after the filter residue is dried, continue to mix the slurry with ultrapure water and slowly add phosphoric acid with a molar mass of 0.5 times the molar mass of lit...

Embodiment 3

[0055] A method for treating high-hetero-hetero lithium iron phosphate waste powder with low consumption of phosphoric acid, comprising the following steps:

[0056]The disassembled high-heterolithium iron phosphate waste powder (mass percentages of impurities C, Cu, and Al are 4.51%, 0.05%, and 0.56%, respectively, and contain a small amount of PVDF) is calcined at 550°C for 6 hours in an argon atmosphere. Fully decompose the binder PVDF. Slurry the waste powder after removing PVDF with ultrapure water at a solid-to-liquid ratio of 1:3, and use energy to convert Al into AlO 2- 1.2 times the theoretical molar amount of LiOH to remove aluminum, the concentration of LiOH in the system is 0.5mol / L, the reaction time is 0.5h, and filtered after the reaction. The filtrate is carbonized to precipitate aluminum, and after the filter residue is dried, continue to slurry with ultrapure water and slowly add phosphoric acid with a molar mass of 0.8 times the molar mass of lithium in lit...

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Abstract

The invention discloses a method for treating high-impurity lithium iron phosphate waste powder by using low-consumption phosphoric acid, which comprises the following steps of: pre-removing aluminum from lithium iron phosphate waste powder subjected to calcination treatment in an alkaline system, leaching aluminum-removed filter residues by using phosphoric acid and hydrogen peroxide, keeping the pH value at 2-3 all the time in the leaching process, selectively leaching Li, removing impurity copper and residual Al in the aluminum-removed filter residues to obtain FePO4 leaching residues, purifying the FePO4 leaching residues by adopting excessive phosphoric acid, supplementing a proper amount of Fe and an oxidizing agent at the same time, further removing impurities such as residual Cu, and converting hydroxyl iron phosphate generated in the selective leaching process into high-purity iron phosphate. The method is simple in process, suitable for treating high-impurity waste lithium iron phosphate powder obtained through disassembly, and capable of directly obtaining battery-grade iron phosphate and lithium phosphate. The method is easy to operate, the consumption of phosphoric acid as a leaching agent is low, the cost is low, the lithium recovery rate is high, and the iron phosphate is high in purity and meets the requirements of battery-grade iron phosphate.

Description

technical field [0001] The invention belongs to the technical field of lithium ion battery materials, and in particular relates to a method for treating high-heterolithic lithium iron phosphate waste powder with low consumption of phosphoric acid. Background technique [0002] Energy and environment issues have a long history, and with the rapid development of science and technology, the conflict between energy and environment has become increasingly acute. Due to the dual attributes of resources and the environment, retired lithium iron phosphate batteries have to develop technologies with low cost and low environmental pollution to recover and regenerate the valuable components in retired lithium iron phosphate batteries. [0003] The content of impurities Cu and Al in the lithium iron phosphate waste powder separated from the common waste lithium iron phosphate batteries in the market is 0.01-0.08% and 0.5-2% respectively, and contains a certain amount of impurities such ...

Claims

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Application Information

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IPC IPC(8): C01B25/37C01B25/30
CPCC01B25/375C01B25/306C01P2006/80Y02W30/84
Inventor 周玉琳曹雁冰林文军廖贻鹏龚亦帆王勇张桂海
Owner ZHUZHOU SMELTER GRP
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