CN115557519A - Method for preparing high-purity lithium fluoride by recycling waste lithium iron phosphate battery positive electrode powder - Google Patents
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- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 title claims abstract description 130
- 238000000034 method Methods 0.000 title claims abstract description 47
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 title claims abstract description 32
- 239000000843 powder Substances 0.000 title claims abstract description 31
- 239000002699 waste material Substances 0.000 title claims abstract description 21
- 238000004064 recycling Methods 0.000 title claims description 15
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 48
- 238000006243 chemical reaction Methods 0.000 claims abstract description 46
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims abstract description 29
- 238000001914 filtration Methods 0.000 claims abstract description 25
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 24
- INHCSSUBVCNVSK-UHFFFAOYSA-L lithium sulfate Inorganic materials [Li+].[Li+].[O-]S([O-])(=O)=O INHCSSUBVCNVSK-UHFFFAOYSA-L 0.000 claims abstract description 22
- RBTVSNLYYIMMKS-UHFFFAOYSA-N tert-butyl 3-aminoazetidine-1-carboxylate;hydrochloride Chemical compound Cl.CC(C)(C)OC(=O)N1CC(N)C1 RBTVSNLYYIMMKS-UHFFFAOYSA-N 0.000 claims abstract description 22
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000000047 product Substances 0.000 claims abstract description 16
- UXFOSWFWQAUFFZ-UHFFFAOYSA-L barium(2+);diformate Chemical compound [Ba+2].[O-]C=O.[O-]C=O UXFOSWFWQAUFFZ-UHFFFAOYSA-L 0.000 claims abstract description 12
- 239000012535 impurity Substances 0.000 claims abstract description 11
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000000292 calcium oxide Substances 0.000 claims abstract description 8
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000000706 filtrate Substances 0.000 claims abstract description 8
- 238000001035 drying Methods 0.000 claims abstract description 7
- HQRPHMAXFVUBJX-UHFFFAOYSA-M lithium;hydrogen carbonate Chemical compound [Li+].OC([O-])=O HQRPHMAXFVUBJX-UHFFFAOYSA-M 0.000 claims abstract description 7
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 6
- 238000002386 leaching Methods 0.000 claims abstract description 5
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 4
- 238000005406 washing Methods 0.000 claims abstract description 3
- 238000003756 stirring Methods 0.000 claims description 27
- 230000035484 reaction time Effects 0.000 claims description 15
- 239000012065 filter cake Substances 0.000 claims description 12
- 238000002360 preparation method Methods 0.000 claims description 6
- 239000008367 deionised water Substances 0.000 claims description 5
- 229910021641 deionized water Inorganic materials 0.000 claims description 5
- 230000007935 neutral effect Effects 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 239000011521 glass Substances 0.000 claims description 2
- 239000002994 raw material Substances 0.000 abstract description 10
- 239000007788 liquid Substances 0.000 abstract description 8
- 239000000243 solution Substances 0.000 description 34
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 10
- 229910052808 lithium carbonate Inorganic materials 0.000 description 10
- 238000005303 weighing Methods 0.000 description 6
- -1 Lithium hexafluorophosphate Chemical compound 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 239000003792 electrolyte Substances 0.000 description 4
- 230000002194 synthesizing effect Effects 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 238000003763 carbonization Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910013872 LiPF Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000010926 waste battery Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D15/00—Lithium compounds
- C01D15/04—Halides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/84—Recycling of batteries or fuel cells
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Secondary Cells (AREA)
Abstract
The invention discloses a method for preparing high-purity lithium fluoride by recovering waste lithium iron phosphate battery positive electrode powder, which comprises the following steps: (1) Adding sulfuric acid and hydrogen peroxide in a certain proportion into the lithium iron phosphate black powder to selectively leach lithium, and filtering to obtain a lithium sulfate leaching solution; (2) Adding a certain amount of sodium hydroxide into the obtained leachate to adjust the pH of the filtrate to 4-6, and filtering to obtain a primary impurity removal solution; (3) Adding a certain proportion of calcium oxide and sodium hydroxide into the primary impurity removal liquid to adjust the pH of the filtrate to 9 to 11, and filtering to obtain a lithium sulfate purified liquid; (4) Carrying out double decomposition reaction on the obtained purified solution and a barium formate solution in a certain proportion, and filtering to obtain a lithium bicarbonate solution; (5) Adding hydrofluoric acid in a certain proportion for reaction, and obtaining the high-purity lithium fluoride product after the procedures of filtering, washing, drying, crushing and the like. The invention synthesizes the lithium fluoride product by adopting a liquid-liquid mode, avoids wrapping raw materials in the product and has high purity of the lithium fluoride product.
Description
Technical Field
The invention relates to the field of preparation of electrolyte salt precursors of lithium ion batteries, in particular to a method for synthesizing high-purity lithium fluoride in a green manner at low cost by a liquid phase method.
Background
Lithium hexafluorophosphate (LiPF) 6 ) Currently, the most important electrolyte is still the most common electrolyte in lithium ion battery electrolyte, and lithium fluoride is one of the key raw materials for producing lithium hexafluorophosphate, and about 0.18 ton of lithium fluoride is needed for producing 1 ton of lithium hexafluorophosphate. With the continuous maturity of lithium ion battery technology and the continuous expansion of application range, the capacity of lithium hexafluorophosphate is also increased, which causes the demand of high-purity lithium fluoride in the world market to increase sharply and the supply to be tense. At present, the preparation route of the lithium fluoride industrial production mostly adopts a neutralization method. The method is a wet process, in which solid lithium carbonate is added into hydrogen fluoride solution to react and separate out lithium fluoride. Although the production method is simple to operate, the defects of high cost of required equipment, low reaction rate, low main content of products, high moisture content, high impurity content and the like exist, and the requirement of raw material indexes for producing lithium hexafluorophosphate cannot be met. The dry process adopts anhydrous HF gas and solid Li 2 CO 3 The method for preparing LiF in the plastic-lined reaction kettle has the advantages of reducing the reaction temperature, having lower requirements on equipment materials and the like, but still has the problems of incomplete reaction and the like
Another method introduced by polyfluoro chemical industries, ltd 4 A method for preparing LiF by reacting an aqueous solution of F with an aqueous solution of LiOH (CN 101376508A). But the method can generate a large amount of ammonia nitrogen waste liquid, has higher environmental protection pressure and lower product purity. At present, the method for overcoming the technical defects of the lithium fluoride production by taking lithium carbonate as a raw material mostly adopts the method of adding carbon dioxide to carbonize indissolvable lithium carbonate into soluble lithium bicarbonate, and lithium fluoride products are produced in a liquid-liquid/gas-liquid mode. However, if industrial-grade lithium carbonate is used as the raw material, an impurity removal process needs to be added to the carbonization process, and if battery-grade lithium carbonate is used as the raw material, the impurity removal process is reduced, but the raw material cost is increased. In a word, the problems of long process route, high cost and the like still exist in the lithium fluoride production by the lithium carbonate carbonization process at present. Book (I)The lithium fluoride product is produced by taking the lithium sulfate purified solution recovered from the anode material of the waste lithium iron phosphate battery as a raw material, so that the effective connection with the battery recovery process is realized, and the problem of long process flow caused by the traditional process that lithium carbonate is recovered and prepared first and then lithium fluoride is prepared by lithium carbonate is solved. After examining the relevant documents, no similar production method is reported in the relevant documents and patents at present.
Disclosure of Invention
The invention aims to provide a method for preparing high-purity lithium fluoride by recycling waste lithium iron phosphate battery positive electrode powder, which takes waste lithium iron phosphate positive electrode powder, hydrofluoric acid and barium formate as raw materials, and the purity of the prepared lithium fluoride meets the standard requirement in YS/T661-2016 battery-grade lithium fluoride.
Based on the above purposes, the technical scheme of the invention is that the method for preparing high-purity lithium fluoride by recovering the anode powder of the waste lithium iron phosphate battery comprises the following steps:
(1) Selectively leaching lithium from the lithium iron phosphate black powder by using a certain amount of sulfuric acid and hydrogen peroxide, and filtering to obtain a lithium sulfate leaching solution;
(2) Adding a certain amount of sodium hydroxide into the filtrate obtained in the step (1) to adjust the pH of the filtrate to 4-6, and filtering to obtain a primary impurity removal solution;
(3) Adding a certain proportion of calcium oxide and sodium hydroxide into the primary impurity removal liquid obtained in the step (2) to adjust the pH of the filtrate to 9-11, and filtering to obtain a lithium sulfate purified liquid;
(4) Adding a barium formate solution in a certain proportion into the lithium sulfate purified solution obtained in the step (3), carrying out double decomposition reaction, and filtering to obtain a lithium bicarbonate solution;
(5) Reacting the lithium bicarbonate solution obtained in the step (4) with hydrofluoric acid in a certain proportion, and filtering, washing, drying, crushing and other processes to obtain a high-purity lithium fluoride product;
according to the method for preparing high-purity lithium fluoride by recycling the waste lithium iron phosphate battery positive electrode powder, in the step (1), the molar ratio of the lithium iron phosphate black powder to sulfuric acid to hydrogen peroxide is 1 to 1.1, preferably 1.02, the stirring speed is 300 to 600r/min, and the adding time of the hydrogen peroxide is 10min. The concentration of the sulfuric acid is 15 to 30wt.%, preferably 15 to 20wt.%, and the concentration of the hydrogen peroxide is 27wt.%. The reaction is carried out in a glass reaction kettle, the reaction temperature is controlled to be 60-90 ℃, preferably 70-80 ℃, and the reaction time is 0.5-4 h, preferably 1.5-3h.
According to the method for preparing high-purity lithium fluoride by recycling the waste lithium iron phosphate battery cathode powder, the adding amount of sodium hydroxide in the step (2) is controlled by the end-point pH, the pH is adjusted to 4 to 6, preferably 5 to 5.5, the reaction is carried out for 10 to 30min, and then the filtration is carried out, preferably 15 to 20min.
According to the method for preparing high-purity lithium fluoride by recycling the waste lithium iron phosphate battery cathode powder, in the step (3), the amount of calcium oxide added is 0.1-1% of the mass fraction of the lithium iron phosphate black powder, the addition amount of sodium hydroxide is controlled by the end point pH, the pH is adjusted to 9-11, preferably 10-10.5, and the mixture is filtered after reaction for 10-30min, preferably 15-20min.
According to the method for preparing high-purity lithium fluoride by recycling the waste lithium iron phosphate battery cathode powder, the stoichiometric ratio of lithium sulfate to barium formate in the step (4) is 1 to 1.1, preferably 1 to 1.05, the reaction temperature is controlled to be 20 to 50 ℃, preferably 20 to 30 ℃, the reaction time is 0.5 to 3h, preferably 1 to 2h, and the stirring rate is 300 to 600r/min.
According to the method for preparing high-purity lithium fluoride by recycling the waste lithium iron phosphate battery cathode powder, in the step (5), the adding speed of hydrofluoric acid is 200 to 300L/h, the mass percent is 30 to 40%, the adding amount of the hydrofluoric acid is calculated according to the final pH value of 3 to 6, the adding speed is preferably 4 to 5, the reaction temperature is controlled to be 30 to 50 ℃, the adding speed is preferably 30 to 40 ℃, the reaction time is 2 to 4 hours, the adding speed is preferably 2.5 to 3.5 hours, and the stirring speed is 300 to 600r/min.
In the method for preparing high-purity lithium fluoride by recycling the waste lithium iron phosphate battery cathode powder, the lithium fluoride filter cake in the step (5) is washed to be neutral by adding deionized water, and then dried for 8 to 14h at the temperature of 100 to 150 ℃.
According to the technical scheme, lithium fluoride is prepared by reacting a lithium sulfate purification solution recovered from waste battery lithium iron phosphate black powder serving as a raw material with hydrofluoric acid after treatment by the process method. Compared with the prior art, the method has the advantages that the method obtains high-purity lithium fluoride by reacting the high-purity lithium carbonate or carbonized lithium carbonate with hydrofluoric acid, recovers the lithium sulfate purified solution to obtain the lithium bicarbonate through double decomposition reaction, and then reacts with the hydrofluoric acid to obtain the high-purity lithium fluoride, so that the method greatly improves the direct recovery rate and purity of the product, reduces the production cost and realizes the green cycle sustainable development of the industrial chain while shortening the recovery end of the battery. The method can prepare a battery-grade lithium fluoride product, the yield of the lithium fluoride in the process is close to 90%, the process is simple and easy to operate, and the product quality is stable.
Drawings
FIG. 1 is a block diagram of the process of the present invention.
Detailed Description
Example 1
I, preparation of lithium sulfate purifying solution: 100g of lithium iron phosphate black powder (the lithium content is 4.5%) and 426.1g of sulfuric acid with the concentration of 15% are weighed and placed in a reaction kettle, and then 82.1g of hydrogen peroxide with the concentration of 27% is weighed and added dropwise within 10min. The stirring speed is set to be 300r/min, the reaction temperature is set to be 60 ℃, and the reaction time is set to be 0.5h. Filtering to obtain leachate after reaction, adding appropriate amount of sodium hydroxide to adjust pH of the solution to 4, stirring for 10min, and filtering to obtain primary impurity-removing solution after stirring. Adding 0.1g of calcium oxide into the primary impurity removal solution, then continuously adding a proper amount of sodium hydroxide to adjust the pH value of the solution to 9, then continuously stirring for 10min, and filtering after stirring to obtain a lithium sulfate purified solution;
and II, synthesizing lithium fluoride, namely adding the lithium sulfate purified solution obtained in the step I into a reaction kettle, and weighing 148.3g of barium formate and adding the barium formate into the reaction kettle. Stirring is carried out for 300r/min, the reaction temperature is 20 ℃, and the reaction time is 0.5h. After the reaction in the previous step is finished, weighing a certain amount of hydrofluoric acid with the concentration of 30%, and controlling the adding speed to be 200L/h until the pH value of the solution is 3. The reaction temperature is set to be 30 ℃, the reaction time is 2h, and the stirring speed is 300r/min. After the reaction is finished, separating a lithium fluoride filter cake, adding deionized water to wash the lithium fluoride filter cake until the lithium fluoride filter cake is neutral, and drying the lithium fluoride filter cake at the temperature of 100 ℃ for 14 hours to obtain 13.5g of a high-purity lithium fluoride product. The purity of the lithium fluoride is detected to be 99.97%.
Example 2
I, preparation of lithium sulfate purifying solution: 100g of lithium iron phosphate black powder (the lithium content is 4.5%) and 335.5g of 20% sulfuric acid are weighed and placed in a reaction kettle, and then 86.2g of 27% hydrogen peroxide is weighed and added dropwise within 10min. Setting the stirring speed of 500r/min, the reaction temperature of 80 ℃ and the reaction time of 2h. Filtering to obtain leachate after reaction, adding appropriate amount of sodium hydroxide to adjust pH of the solution to 5, stirring for 20min, and filtering to obtain primary impurity-removing solution after stirring. Adding 0.5g of calcium oxide into the primary impurity removal solution, continuously adding a proper amount of sodium hydroxide to adjust the pH value of the solution to 10, continuously stirring for 20min, and filtering after stirring to obtain a lithium sulfate purified solution;
and II, synthesizing lithium fluoride, namely adding the lithium sulfate purified solution obtained in the step I into a reaction kettle, and weighing 155.7g of barium formate and adding the barium formate into the reaction kettle. Stirring is carried out for 500r/min, the reaction temperature is 30 ℃, and the reaction time is 2h. After the reaction in the previous step is finished, weighing a certain amount of 35% hydrofluoric acid, and controlling the adding speed to be 250L/h until the pH value of the solution is 4. The reaction temperature is set to be 40 ℃, the reaction time is 3 hours, and the stirring speed is 500r/min. After the reaction is finished, separating the lithium fluoride filter cake, adding deionized water to wash the lithium fluoride filter cake to be neutral, and drying the lithium fluoride filter cake for 12 hours at the temperature of 120 ℃ to obtain 14.3g of high-purity lithium fluoride product. The purity of the lithium fluoride is detected to be 99.96%.
Example 3
I, preparation of lithium sulfate purifying solution: 100g of lithium iron phosphate black powder (the lithium content is 4.5%) and 234.4g of sulfuric acid with the concentration of 30% are weighed and placed in a reaction kettle, and then 90.3g of hydrogen peroxide with the concentration of 27% is weighed and added dropwise within 10min. Setting the stirring speed of 600r/min, the reaction temperature of 90 ℃ and the reaction time of 4h. Filtering to obtain leachate after reaction, adding appropriate amount of sodium hydroxide to adjust pH of the solution to 6, stirring for 30min, and filtering to obtain primary impurity-removing solution after stirring. Adding 1g of calcium oxide into the primary impurity removal solution, continuously adding a proper amount of sodium hydroxide to adjust the pH value of the solution to 11, continuously stirring for 30min, and filtering after stirring to obtain a lithium sulfate purified solution;
and II, synthesizing lithium fluoride, namely adding the lithium sulfate purified solution obtained in the step I into a reaction kettle, and weighing 163.1g of barium formate and adding the barium formate into the reaction kettle. Stirring is carried out for 600r/min, the reaction temperature is 50 ℃, and the reaction time is 3h. After the reaction in the previous step is finished, weighing a certain amount of hydrofluoric acid with the concentration of 40%, and controlling the adding speed to be 300L/h until the pH value of the solution is 6. Setting the reaction temperature at 50 ℃, the reaction time at 4h and the stirring speed at 600r/min. After the reaction is finished, separating the lithium fluoride filter cake, adding deionized water to wash the lithium fluoride filter cake to be neutral, and drying the lithium fluoride filter cake for 8 hours at the temperature of 150 ℃ to obtain 15.1g of high-purity lithium fluoride product. The purity of the lithium fluoride is detected to be 99.96%.
Claims (7)
1. A method for preparing high-purity lithium fluoride by recovering waste lithium iron phosphate battery positive electrode powder is characterized by comprising the following preparation steps:
(1) Selectively leaching lithium from the lithium iron phosphate black powder by using a certain amount of sulfuric acid and hydrogen peroxide, and filtering to obtain a lithium sulfate leaching solution;
(2) Adding a certain amount of sodium hydroxide into the filtrate obtained in the step (1) to adjust the pH of the filtrate to 4-6, and filtering to obtain a primary impurity removal solution;
(3) Adding a certain proportion of calcium oxide and sodium hydroxide into the primary impurity-removed solution obtained in the step (2) to adjust the pH of the filtrate to 9-11, and filtering to obtain a lithium sulfate purified solution;
(4) Adding a barium formate solution in a certain proportion into the lithium sulfate purified solution obtained in the step (3), carrying out double decomposition reaction, and filtering to obtain a lithium bicarbonate solution;
(5) Reacting the lithium bicarbonate solution obtained in the step (4) with hydrofluoric acid in a certain proportion, and filtering, washing, drying, crushing and the like to obtain a high-purity lithium fluoride product.
2. The method for preparing high-purity lithium fluoride by recycling waste lithium iron phosphate battery positive electrode powder according to claim 1, wherein the molar ratio of the lithium iron phosphate black powder to the sulfuric acid to the hydrogen peroxide in the step (1) is 1 to 1.1, the stirring speed is 300 to 600r/min, and the adding time of the hydrogen peroxide is 10min; the concentration of the used sulfuric acid is 15 to 30wt.%, and the concentration of hydrogen peroxide is 27wt.%; the reaction is carried out in a glass reaction kettle, the reaction temperature is controlled to be 60 to 90 ℃, and the reaction time is 0.5 to 4 hours.
3. The method for preparing high-purity lithium fluoride by recycling the positive electrode powder of the waste lithium iron phosphate batteries according to claim 1, wherein the adding amount of the sodium hydroxide in the step (2) is controlled by a terminal pH, the pH is adjusted to 4 to 6, and the lithium fluoride is filtered after the reaction is carried out for 10 to 30min.
4. The method for preparing high-purity lithium fluoride by recycling waste lithium iron phosphate battery positive electrode powder according to claim 1, wherein the amount of calcium oxide added in the step (3) is 0.1-1% of the mass fraction of the lithium iron phosphate black powder, the addition amount of sodium hydroxide is controlled by the end point pH, the pH is adjusted to 9-11, and the lithium iron phosphate battery positive electrode powder is filtered after reaction for 10-30min.
5. The method for preparing high-purity lithium fluoride by recycling the waste lithium iron phosphate battery positive electrode powder according to claim 1, wherein the stoichiometric ratio of lithium sulfate to barium formate in the step (4) is 1 to 1.1, the reaction temperature is controlled to be 20 to 50 ℃, the reaction time is 0.5 to 3 hours, and the stirring speed is 300 to 600r/min.
6. The method for preparing high-purity lithium fluoride by recycling the positive electrode powder of the waste lithium iron phosphate battery according to claim 1, wherein the adding speed of hydrofluoric acid in the step (5) is 200 to 300L/h, the mass percent is 30 to 40%, the adding amount of the hydrofluoric acid is controlled by the end point pH of 3 to 6, the reaction temperature is controlled to be 30 to 50 ℃, the reaction time is 2 to 4h, and the stirring speed is 300 to 600r/min.
7. The method for preparing high-purity lithium fluoride by recycling the positive electrode powder of the waste lithium iron phosphate batteries according to claim 1, wherein the lithium fluoride filter cake is washed to be neutral by adding deionized water in the step (5), and then dried for 8 to 14h at the temperature of 100 to 150 ℃.
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| CN114538481A (en) * | 2022-03-29 | 2022-05-27 | 江西飞宇新能源科技有限公司 | Technical method for preparing lithium fluoride from industrial-grade lithium carbonate |
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| CN110451535A (en) * | 2019-08-15 | 2019-11-15 | 湖南顺华锂业有限公司 | A kind of method of lithium sulfate solution purification and impurity removal |
| CN113912032A (en) * | 2021-09-16 | 2022-01-11 | 湖北锂宝新材料科技发展有限公司 | Method for recovering and preparing battery-grade lithium carbonate and iron phosphate from waste lithium iron phosphate battery positive electrode powder |
| CN114538481A (en) * | 2022-03-29 | 2022-05-27 | 江西飞宇新能源科技有限公司 | Technical method for preparing lithium fluoride from industrial-grade lithium carbonate |
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| Title |
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| 申泮文等主编: "《化合物词典》", vol. 1, 上海辞书出版社, pages: 214 * |
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