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Method for preparing high-purity lithium sulfate from waste liquid recovered from hydrothermal method based lithium iron phosphate production

A technology of lithium iron phosphate and lithium sulfate, applied in the direction of lithium sulfate/sulfite, etc., can solve the problems affecting the quality of lithium products, pollution, lithium can not be fully recovered, etc.

Inactive Publication Date: 2018-04-17
TIANQI LITHIUM CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] For the waste liquid produced in the process of synthesizing lithium iron phosphate by the existing hydrothermal method, for the recovery of lithium, some of it is recovered in the form of precipitate by chemical precipitation, but the organic matter in the mother liquor is not treated, and the mother liquor also contains a small amount of Not only the lithium cannot be completely recovered, but the mother liquor will also cause a lot of pollution if the mother liquor is discharged casually; although some lithium in the waste liquid of the LFP process can be recycled, but because the outlet of the organic matter is not considered, the richness of the organic matter in the mother liquor More and more gatherings will eventually affect the quality of recovered lithium products; both of the above are deficiencies in the existing technology

Method used

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  • Method for preparing high-purity lithium sulfate from waste liquid recovered from hydrothermal method based lithium iron phosphate production
  • Method for preparing high-purity lithium sulfate from waste liquid recovered from hydrothermal method based lithium iron phosphate production

Examples

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Effect test

Embodiment 1

[0028] Get LFP process waste liquid 2L (pH 3.51, main component is Li + : 9.4g / L, Fe 2+ : 0.5g / L, ascorbic acid: 1g / L, furfural: 0.02g / L), add sodium hydroxide to it after boiling, adjust the pH value to 6.5, react for 15min; add 30% hydrogen peroxide 4.5ml, add activated carbon after reacting for 15min 20g, reacted for 15min and filtered to obtain 29.4g of filter residue. The filter residue is stirred and washed with 294ml of dilute sulfuric acid with a mass concentration of 10% for 15 minutes, and the solid obtained after filtration is used as an adsorbent for cyclic adsorption; the filtrate is heated and evaporated to concentrate a large amount of solids, and after cooling, it is centrifugally separated, and the mother liquor is returned to the raw material lithium iron phosphate From the waste liquid, the wet material was separated by centrifugation, put into an oven and baked at 110°C for 4 hours to obtain 83.1 g of high-purity anhydrous lithium sulfate. The direct reco...

Embodiment 2

[0030] Get LFP process waste liquid 3L (pH 3.45, main component is Li + : 8.9g / L, Fe 2+ : 0.6g / L, ascorbic acid: 0.1g / L, furfural: 0.82g / L), after boiling, add sodium hydroxide to it, adjust the pH value to 6, react for 18min; add 1.8ml of 30% hydrogen peroxide, react for 20min, then add Activated carbon 30g, reacted for 15min and filtered to obtain 41.4g of filter residue; the filter residue was stirred and washed with 414ml of 6% dilute sulfuric acid for 20min, and the solid obtained after filtration was used as an adsorbent for cyclic adsorption; the filtrate was heated, evaporated and concentrated until a large amount of solids were precipitated. After centrifugation, the mother liquor was returned to the raw material lithium iron phosphate waste liquid, and the wet material was centrifugally separated and put into an oven for drying at 120° C. for 5 hours to obtain 120.45 g of high-purity anhydrous lithium sulfate. The direct recovery rate of lithium in the waste liquid ...

Embodiment 3

[0032] Get LFP process waste liquid 10L (pH 3.49, main component is Li + : 8.9g / L, Fe 2+ : 0.56g / L, citric acid: 0.95g / L,), add 30% hydrogen peroxide 3.1ml, add sodium hydroxide to it after boiling, adjust the pH value to 7, react for 16min; add montmorillonite 120g after reacting for 15min After 20 minutes of reaction, 170 g of filter residue was obtained by filtration; the filter residue was stirred and washed with 1700 ml of 5% dilute sulfuric acid for 18 minutes, and the solid obtained after filtration was used as an adsorbent for cyclic adsorption; , the mother liquor was returned to the raw material lithium iron phosphate waste liquid, the wet material was centrifuged and put into an oven for 5.5 hours at 125°C to obtain 414.5g of high-purity anhydrous lithium sulfate. The direct recovery rate of lithium in the waste liquid of this embodiment is 59.3%, and the purity of the prepared high-purity anhydrous lithium sulfate is 99.95%.

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Abstract

The invention belongs to the technical field of lithium iron phosphate waste liquid recovery and provides a method for preparing high-purity lithium sulfate from waste liquid recovered from hydrothermal method based lithium iron phosphate production. The method includes: 1) boiling waste liquid generated in a hydrothermal method based lithium iron phosphate production process, and adding sodium hydroxide to adjust pH; 2) adding hydrogen peroxide, adding an adsorbent after reaction, and filtering after reaction; 3) subjecting filtrate to evaporation concentration, centrifugal separation and drying to obtain high-purity anhydrous lithium sulfate; 4) stirring and washing filter residues with dilute sulfuric acid, and filtering to use as an adsorbent for cyclic adsorption. By hydrogen peroxide, residual organics in waste liquid is oxidized and decomposed or converted into easily-adsorbable organics, and the adsorbent is used for adsorption to remove the organics; after oxidization, adsorption and decontamination, solution is crystallized to obtain high-purity lithium sulfate, and the filter residues subjected to dilute sulfuric acid washing, stirring and filtering serve as the adsorbent for cyclic adsorption. Purity of the high-purity lithium sulfate prepared according to the method reaches 99.90%.

Description

technical field [0001] The invention belongs to the technical field of recycling lithium iron phosphate waste liquid, and specifically relates to a method for preparing high-purity lithium sulfate by recovering lithium iron phosphate waste liquid produced by a hydrothermal method. Background technique [0002] Lithium iron phosphate battery is a widely used lithium-ion secondary battery, and there are two main methods for the synthesis of lithium iron phosphate as its cathode material: solid-state method and hydrothermal method. Among them, the hydrothermal method is a relatively advanced method for the preparation of lithium iron phosphate cathode materials. Since the synthesis process is carried out in a reactor, the raw materials are mixed at the ion and molecular level, and the quality of the material is uniform. With the scale-up of production, the quality uniformity can be further improved. The production raw materials are all in solution state, which is convenient fo...

Claims

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Application Information

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IPC IPC(8): C01D15/06
CPCC01D15/06C01P2006/80
Inventor 曹乃珍高洁陈格徐川李仕红
Owner TIANQI LITHIUM CORP
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