CN116143609A - Method for preparing high-purity lithium formate monohydrate by using battery-grade lithium hydroxide monohydrate - Google Patents
Method for preparing high-purity lithium formate monohydrate by using battery-grade lithium hydroxide monohydrate Download PDFInfo
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- RDAKCPVJSPEDON-UHFFFAOYSA-M lithium;formate;hydrate Chemical compound [Li+].O.[O-]C=O RDAKCPVJSPEDON-UHFFFAOYSA-M 0.000 title claims abstract description 92
- 238000000034 method Methods 0.000 title claims abstract description 37
- PQVSTLUFSYVLTO-UHFFFAOYSA-N ethyl n-ethoxycarbonylcarbamate Chemical compound CCOC(=O)NC(=O)OCC PQVSTLUFSYVLTO-UHFFFAOYSA-N 0.000 title claims abstract description 34
- GLXDVVHUTZTUQK-UHFFFAOYSA-M lithium hydroxide monohydrate Substances [Li+].O.[OH-] GLXDVVHUTZTUQK-UHFFFAOYSA-M 0.000 title claims abstract description 34
- 229940040692 lithium hydroxide monohydrate Drugs 0.000 title claims abstract description 34
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims abstract description 48
- 238000001914 filtration Methods 0.000 claims abstract description 41
- 238000003756 stirring Methods 0.000 claims abstract description 30
- 235000019253 formic acid Nutrition 0.000 claims abstract description 25
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000012535 impurity Substances 0.000 claims abstract description 19
- 238000001291 vacuum drying Methods 0.000 claims abstract description 17
- 238000001816 cooling Methods 0.000 claims abstract description 16
- 238000001704 evaporation Methods 0.000 claims abstract description 12
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 9
- 238000005406 washing Methods 0.000 claims abstract description 9
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 102
- XKPJKVVZOOEMPK-UHFFFAOYSA-M lithium;formate Chemical compound [Li+].[O-]C=O XKPJKVVZOOEMPK-UHFFFAOYSA-M 0.000 claims description 54
- 239000013078 crystal Substances 0.000 claims description 44
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical group CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 34
- 238000006243 chemical reaction Methods 0.000 claims description 20
- 239000002002 slurry Substances 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 10
- 239000003960 organic solvent Substances 0.000 claims description 9
- 238000001035 drying Methods 0.000 claims description 8
- 238000004090 dissolution Methods 0.000 claims description 6
- 230000001376 precipitating effect Effects 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 6
- 150000001298 alcohols Chemical class 0.000 claims description 3
- 150000002170 ethers Chemical class 0.000 claims description 3
- 150000002576 ketones Chemical class 0.000 claims description 3
- 238000003912 environmental pollution Methods 0.000 abstract description 3
- 238000009461 vacuum packaging Methods 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 50
- 238000004519 manufacturing process Methods 0.000 description 8
- 239000000463 material Substances 0.000 description 7
- 230000018044 dehydration Effects 0.000 description 5
- 238000006297 dehydration reaction Methods 0.000 description 5
- 239000012141 concentrate Substances 0.000 description 3
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 125000000896 monocarboxylic acid group Chemical group 0.000 description 3
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- 239000012670 alkaline solution Substances 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
- PWBXDCPGSHVVPB-UHFFFAOYSA-K [O-]P([O-])(=O)OP(=O)([O-])O.[Fe+2].[Li+] Chemical compound [O-]P([O-])(=O)OP(=O)([O-])O.[Fe+2].[Li+] PWBXDCPGSHVVPB-UHFFFAOYSA-K 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000008832 photodamage Effects 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/41—Preparation of salts of carboxylic acids
- C07C51/412—Preparation of salts of carboxylic acids by conversion of the acids, their salts, esters or anhydrides with the same carboxylic acid part
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
-
- 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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Crystallography & Structural Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides a method for preparing high-purity lithium formate monohydrate by using battery-grade lithium hydroxide monohydrate. The method comprises the following steps: A. dissolving lithium hydroxide monohydrate; B. neutralization reaction; C. filtering and removing impurities; d, evaporating and concentrating; E. cooling, crystallizing and filtering; F. organic stirring and washing; G. and (5) vacuum drying and packaging. The method for preparing the high-purity lithium formate monohydrate by using the battery-grade lithium hydroxide monohydrate and the industrial formic acid has the advantages of simple process, high yield, high economic value and small environmental pollution.
Description
Technical Field
The invention relates to a method for preparing high-purity lithium formate monohydrate by using battery-grade lithium hydroxide monohydrate.
Background
Lithium formate monohydrate is used as an excellent nonlinear optical material, and has the advantages of high nonlinear coefficient, high photodamage threshold, wide light transmission wave band, ultraviolet extension and Nd: the YAG laser 1.06 mu m can realize the characteristics of frequency tripling, frequency quadrupling and the like, and has wide application prospect. In recent years, lithium formate is an important member in the lithium chemical industry, and enjoys a unique advantage in the development of lithium batteries. The lithium formate can be used for preparing lithium iron phosphate or lithium iron pyrophosphate which are anode materials of lithium ion batteries and used as spraying materials on the surface of a positive electrode precursor material. The existing production process of lithium formate with wide application prospect faces the defects of low production purity, more impurities and the like, so that an advanced lithium formate monohydrate preparation process is needed to improve the overall quality of lithium formate monohydrate products in the industry.
Disclosure of Invention
Based on the above, it is necessary to provide a method for preparing high-purity lithium formate monohydrate by using battery-grade lithium hydroxide, which is simple, convenient, easy to operate, safe, reliable, low in production cost, low in equipment investment, easy for mass production, transparent in color and high in purity (purity not less than 99.9%), and can effectively solve the problems of unstable water content caused by low main content of the existing lithium formate monohydrate and difficult dehydration.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a method for preparing high-purity lithium formate monohydrate by using battery-grade lithium hydroxide monohydrate, comprising the following steps:
A. dissolution of battery grade lithium hydroxide monohydrate: under the normal temperature condition, pouring 200-400 g of battery grade lithium hydroxide monohydrate into a reaction container filled with pure water, and stirring for 10-20 min to obtain a lithium hydroxide solution, wherein the mass liquid-solid ratio of the pure water to the lithium hydroxide monohydrate is 2-3:1;
B. neutralization reaction: slowly pouring lithium hydroxide into the lithium hydroxide solution obtained in the step A under the stirring condition at normal temperature, wherein the molar ratio of the lithium hydroxide is as follows: an industrial formic acid solution with the formic acid of 1:1, wherein the adding rate of the formic acid is 30-50 ml/min, stirring and reacting for 20-40 min, and adjusting the pH value to 7-9 by using lithium hydroxide after the reaction to detect that the pH value is 7-9 without change;
C. filtering and removing impurities: filtering the solution with the pH value of 7-9 obtained in the step B while the solution is hot at normal temperature, and removing alkaline insoluble substances and other impurities to obtain a clear and transparent lithium formate solution;
D. and (3) evaporating and concentrating: c, evaporating and concentrating the clear and transparent lithium formate obtained in the step C, wherein the concentration temperature is 110-120 ℃, and then cooling to 80-90 ℃ to obtain a lithium formate concentrated solution;
E. cooling, crystallizing and filtering: adding 10-20 g of lithium formate monohydrate crystals into the lithium formate concentrated solution obtained in the step D under normal pressure, cooling to 30-50 ℃, at this time, precipitating a large number of lithium formate monohydrate crystals in the lithium formate slurry, and filtering to obtain white needle-shaped lithium formate monohydrate crystals;
F. organic stirring and washing: e, pouring the white needle-shaped lithium formate monohydrate crystal obtained by filtering in the step E into a container filled with 1-2 times of organic solvent with the mass of lithium formate monohydrate, stirring for 20-40 min, and then filtering to obtain the lithium formate monohydrate crystal;
G. vacuum drying: and F, placing the lithium formate monohydrate crystal obtained in the step F into a vacuum drying oven, and drying for 2-4 hours at 25-45 ℃ to obtain the high-purity lithium formate monohydrate.
Further, the mass concentration of the technical formic acid solution in the step B is 85%.
Further, the solution in the step C is weakly alkaline, and a sand core funnel with a diameter of 3-5um is adopted for filtering.
Further, the organic solvent in the step F is at least one of alcohols, ethers and ketones.
Further, the organic solvent in the step F is ethanol, the mass of the ethanol is 1-2 times of that of the lithium formate monohydrate, and the stirring is carried out for 20-40 min.
The invention relates to a method for preparing high-purity lithium formate monohydrate by using battery-grade lithium hydroxide monohydrate. And concentrating the lithium formate solution, namely heating and concentrating to a certain temperature at normal pressure to remove redundant water in the lithium formate solution, cooling, crystallizing, filtering, adding anhydrous organic stirring and washing to remove attached impurities and redundant water, and finally vacuum drying to obtain the lithium formate monohydrate with the main content of more than 99.9 percent. In the whole process, the method has simple requirements on equipment, loose requirements on environment, short flow and simple process. Solves the problems of difficult dehydration and the like caused by the crystallization water of the lithium formate obtained in the traditional production, and solves the problems of high water content and low purity of the lithium formate prepared by the traditional process.
The invention relates to a method for preparing high-purity lithium formate monohydrate by using battery-grade lithium hydroxide, which uses battery-grade lithium hydroxide and formic acid for neutralization reaction, and then uses lithium hydroxide to adjust the pH value of the solution to 8-9, thus obtaining weakly alkaline solution, filtering by adopting a 3-5um sand core funnel, and removing alkaline insoluble substances and other impurities, wherein the reaction equation is as follows: liOH H 2 O + HCOOH → HCOOLi+ 2H 2 O, the obtained lithium formate solution is evaporated and concentrated at normal pressure to obtain hot saturated lithium formate solution. Lithium formate monohydrate seed crystals are added to form lithium formate monohydrate crystals of higher purity. And the solubility difference that formic acid and water are dissolved in ethanol and lithium formate is slightly dissolved in ethanol is utilized, the lithium formate monohydrate is stirred and washed by ethanol, and free water attached to the lithium formate monohydrate is replaced by volatile ethanol, so that the lithium formate monohydrate can be obtained by drying at a lower temperature. And simultaneously, the ethanol can be reused through dehydration.
The method for preparing the high-purity lithium formate monohydrate by using the battery-grade lithium hydroxide has the advantages of simple process, low raw material production cost, high economic value, easy realization of industrialization and small environmental pollution, and the high-purity lithium formate monohydrate with transparent color and the main content of more than 99.9 percent is obtained.
Detailed Description
The invention will be described more fully hereinafter with reference to the accompanying examples in order to facilitate an understanding of the invention, however, the invention may be embodied in many different forms and is not limited to the examples described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
The invention provides a method for preparing high-purity lithium formate monohydrate by using battery-grade lithium hydroxide monohydrate, which comprises the following steps:
A. dissolution of battery grade lithium hydroxide monohydrate: under the normal temperature condition, pouring 200-400 g of battery grade lithium hydroxide monohydrate into a reaction container filled with pure water, and stirring for 10-20 min to obtain a lithium hydroxide solution, wherein the mass liquid-solid ratio of the pure water to the lithium hydroxide monohydrate is 2-3:1;
B. neutralization reaction: slowly pouring lithium hydroxide into the lithium hydroxide solution obtained in the step A under the stirring condition at normal temperature, wherein the molar ratio of the lithium hydroxide is as follows: an industrial formic acid solution with the formic acid of 1:1, wherein the adding rate of the formic acid is 30-50 ml/min, stirring and reacting for 20-40 min, and adjusting the pH value to 7-9 by using lithium hydroxide after the reaction to detect that the pH value is 7-9 without change;
C. filtering and removing impurities: filtering the solution with the pH value of 7-9 obtained in the step B while the solution is hot at normal temperature, and removing alkaline insoluble substances and other impurities to obtain a clear and transparent lithium formate solution;
D. and (3) evaporating and concentrating: c, evaporating and concentrating the clear and transparent lithium formate obtained in the step C, wherein the concentration temperature is 110-120 ℃, and then cooling to 80-90 ℃ to obtain a lithium formate concentrated solution;
E. cooling, crystallizing and filtering: adding 10-20 g of lithium formate monohydrate crystals into the lithium formate concentrated solution obtained in the step D under normal pressure, cooling to 30-50 ℃, at this time, precipitating a large number of lithium formate monohydrate crystals in the lithium formate slurry, and filtering to obtain white needle-shaped lithium formate monohydrate crystals;
F. organic stirring and washing: e, pouring the white needle-shaped lithium formate monohydrate crystal obtained by filtering in the step E into a container filled with 1-2 times of organic solvent with the mass of lithium formate monohydrate, stirring for 20-40 min, and then filtering to obtain the lithium formate monohydrate crystal;
G. vacuum drying: and F, placing the lithium formate monohydrate crystal obtained in the step F into a vacuum drying oven, and drying for 2-4 hours at 25-45 ℃ to obtain the high-purity lithium formate monohydrate.
Furthermore, the pure water added in the step A is 2-3 times of that of battery-grade lithium hydroxide monohydrate, so that most of lithium hydroxide is dissolved, and meanwhile, the pure water consumption is reduced to reduce the energy consumption of subsequent evaporation and concentration.
Furthermore, the industrial formic acid solution in the step B is national standard industrial formic acid with the mass concentration of 85%, the reaction releases heat, the formic acid is added slowly and at the speed of 30-50 ml/min, and the pH at the end point of the reaction is 7-9, so that the reaction is slightly alkaline.
Further, the step C is characterized in that the solution is weakly alkaline, the pH value is 7-9, and a sand core funnel with a diameter of 3-5um is adopted for filtering, so that alkaline insoluble substances and other impurities can be removed through filtering.
Furthermore, the step D is characterized in that the temperature of the concentration end point under normal pressure is 110-120 ℃, the viscosity of the solution is not high, at the moment, the crystallization water in the lithium formate solution is not lost, and the lithium formate solution is cooled to 80-90 ℃ to obtain the lithium formate concentrated solution.
Furthermore, when the step E is used for cooling and crystallizing, 10-20 g of lithium formate monohydrate crystals are added into the lithium formate slurry to serve as seed crystals, so that a large amount of lithium formate monohydrate crystals are conveniently precipitated, and the obtained lithium formate crystals are cooled and crystallized to 30-50 ℃ so that the volume ratio of the obtained crystal material is preferably 30-35%.
Further, the organic solvent in the step F is alcohols, ethers, ketones, etc., which are insoluble or slightly soluble in lithium formate, and the organic solvent is miscible with water. Ethanol is preferred as the solvent. And adding ethanol with the mass 1-2 times of that of the lithium formate monohydrate, and stirring for 20-40 min to sufficiently remove water attached to the lithium formate monohydrate crystal.
Furthermore, the temperature of the vacuum drying process in the step G needs to be controlled at 25-45 ℃ in a vacuum drying box to prevent the lithium formate monohydrate from losing crystal water.
The invention relates to a method for preparing high-purity lithium formate monohydrate by using battery-grade lithium hydroxide monohydrate. And concentrating the lithium formate solution, namely heating and concentrating to a certain temperature at normal pressure to remove redundant water in the lithium formate solution, cooling, crystallizing, filtering, adding anhydrous organic stirring and washing to remove attached impurities and redundant water, and finally vacuum drying to obtain the lithium formate monohydrate with the main content of more than 99.9 percent. In the whole process, the method has simple requirements on equipment, loose requirements on environment, short flow and simple process. Solves the problems of difficult dehydration and the like caused by the crystallization water of the lithium formate obtained in the traditional production, and solves the problems of high water content and low purity of the lithium formate prepared by the traditional process.
The invention relates to a method for preparing high-purity lithium formate monohydrate by using battery-grade lithium hydroxide, which uses battery-grade lithium hydroxide and formic acid for neutralization reaction, and then uses lithium hydroxide to adjust the pH value of the solution to 8-9, thus obtaining weakly alkaline solution, filtering by adopting a 3-5um sand core funnel, and removing alkaline insoluble substances and other impurities, wherein the reaction equation is as follows: liOH H 2 O + HCOOH → HCOOLi+ 2H 2 O, the obtained lithium formate solution is evaporated and concentrated at normal pressure to obtain hot saturated lithium formate solution. Lithium formate monohydrate seed crystals are added to form lithium formate monohydrate crystals of higher purity. The solubility difference that formic acid and water are dissolved in ethanol and lithium formate is slightly dissolved in ethanol is utilized, and the lithium formate monohydrate is stirred and washed by ethanol, so that the free water attached to the lithium formate monohydrate is replaced byAnd ethanol which is easy to volatilize so as to ensure that lithium formate monohydrate can be obtained by drying at a lower temperature. And simultaneously, the ethanol can be reused through dehydration.
The method for preparing the high-purity lithium formate monohydrate by using the battery-grade lithium hydroxide has the advantages of simple process, low raw material production cost, high economic value, easy realization of industrialization and small environmental pollution, and the high-purity lithium formate monohydrate with transparent color and the main content of more than 99.9 percent is obtained.
Example 1
A. Dissolution of battery grade lithium hydroxide monohydrate: under normal temperature, 200g of battery grade lithium hydroxide monohydrate is poured into a reaction vessel filled with pure water, and the pure water with the mass liquid-solid ratio of the pure water to the lithium hydroxide monohydrate of 3:1 is stirred for 10min to obtain a lithium hydroxide solution.
B. Neutralization reaction: slowly pouring the lithium hydroxide solution obtained in the step A into a molar ratio of Li to COOH under the stirring condition at normal temperature - Formic acid solution with the concentration of 1:1 is 85 percent, the adding rate is 50ml/min, the pH value is adjusted to 9 by lithium hydroxide after the reaction, and then the reaction is stirred for 30min.
C. Filtering and removing impurities: the solution with the pH value of 9 obtained in the step B is filtered at normal temperature, and alkaline insoluble substances and other impurities are removed, so as to obtain 1050.5g of clear and transparent lithium formate solution.
D. And (3) evaporating and concentrating: the clear and transparent lithium formate obtained in the step C was concentrated by evaporation to 117℃and then cooled to 80℃to give 542.2g of a formic acid concentrate.
E. Cooling, crystallizing and filtering: and D, adding 10g of lithium formate monohydrate crystals into the lithium formate slurry obtained in the step D under normal pressure, cooling to 40 ℃, at this time, precipitating a large number of lithium formate monohydrate crystals in the lithium formate slurry, and filtering at constant temperature to obtain 135.5g of lithium formate monohydrate wet material.
F. Organic stirring and washing: and E, pouring the lithium formate monohydrate crystal obtained by filtering in the step E into a container filled with ethanol with the mass being 2 times that of the lithium formate monohydrate, stirring for 40 minutes, and then filtering to obtain 131.5g of lithium formate monohydrate crystal.
G. Vacuum drying: and F, putting the lithium formate monohydrate crystal obtained in the step F into a vacuum drying oven, and drying at 35 ℃ for 3 hours to obtain 112.3g of high-purity lithium formate monohydrate. The main content is 99.95 percent.
Example 2
A. Dissolution of battery grade lithium hydroxide monohydrate: at normal temperature, 400g of battery grade lithium hydroxide monohydrate is poured into a reaction vessel filled with pure water, and the pure water with the mass liquid-solid ratio of the pure water to the lithium hydroxide monohydrate of 2.5:1 is stirred for 15min to obtain a lithium hydroxide solution.
B. Neutralization reaction: slowly pouring the lithium hydroxide solution obtained in the step A into a molar ratio of Li to COOH under the stirring condition at normal temperature - Formic acid solution with the concentration of 1:1 is 85 percent, the adding rate is 40ml/min, the pH value is regulated to 7 by lithium hydroxide after the reaction, and then the reaction is stirred for 40min.
C. Filtering and removing impurities: the solution with the pH of 7 obtained in the step B is filtered at normal temperature, and alkaline insoluble substances and other impurities are removed, thus obtaining 1895.7g of clear and transparent lithium formate solution.
D. And (3) evaporating and concentrating: the clear and transparent lithium formate obtained in the step C is evaporated and concentrated to 119 ℃, and then cooled to 90 ℃ to obtain 1036.5g of lithium formate concentrate.
E. Cooling and crystallizing: and D, adding 20g of lithium formate monohydrate crystals into the lithium formate slurry obtained in the step D under normal pressure, cooling to 50 ℃, at this time, precipitating a large number of lithium formate monohydrate crystals in the lithium formate slurry, and filtering at constant temperature to obtain 306.8g of lithium formate monohydrate wet material.
F. Organic stirring and washing: and E, pouring the lithium formate monohydrate crystal obtained by filtering in the step E into a container filled with heavy ethanol such as lithium formate monohydrate and the like, stirring for 30min, and then filtering to obtain 297.6g of lithium formate monohydrate crystal.
G. Vacuum drying: and F, putting the lithium formate monohydrate crystal obtained in the step F into a vacuum drying oven, and drying at 45 ℃ for 2 hours to obtain 253.3g of high-purity lithium formate monohydrate with the main content of 99.93%.
Example 3
A. Dissolution of battery grade lithium hydroxide monohydrate: under normal temperature, 300g of battery grade lithium hydroxide monohydrate is poured into a reaction vessel filled with pure water, and the pure water with the mass liquid-solid ratio of the pure water to the lithium hydroxide monohydrate of 2:1 is stirred for 20min to obtain a lithium hydroxide solution.
B. Neutralization reaction: slowly pouring the lithium hydroxide solution obtained in the step A into a molar ratio of Li to COOH under the stirring condition at normal temperature - Formic acid solution with the concentration of 1:1 is 85 percent, the adding rate is 30ml/min, the pH value is adjusted to 8 by lithium hydroxide after the reaction, and then the reaction is stirred for 20min.
C. Filtering and removing impurities: the solution with pH of 8 obtained in the step B is filtered while hot at normal temperature, and alkaline insoluble substances and other impurities are removed, thus obtaining 1281.7g of clear and transparent lithium formate solution.
D. And (3) evaporating and concentrating: the clear and transparent lithium formate obtained in the step C is evaporated and concentrated to 115 ℃ and then cooled to 85 ℃ to obtain 836.4g of lithium formate concentrate.
E. Cooling and crystallizing: and D, adding 10g of lithium formate monohydrate crystals into the lithium formate slurry obtained in the step D under normal pressure, cooling to 45 ℃, at this time, precipitating a large number of lithium formate monohydrate crystals in the lithium formate slurry, and filtering at constant temperature to obtain 206.6g of lithium formate monohydrate wet material.
F. Organic stirring and washing: and E, pouring the lithium formate monohydrate crystal obtained by filtering in the step E into a container filled with ethanol with the mass 1.5 times that of the lithium formate monohydrate, stirring for 20min, and then filtering to obtain 201.5g of the lithium formate monohydrate crystal.
G. Vacuum drying: and F, putting the lithium formate monohydrate crystal obtained in the step F into a vacuum drying oven, and drying for 4 hours at 25 ℃ to obtain 178.3g of high-purity lithium formate monohydrate with the main content of 99.92%.
The foregoing description of the embodiments of the present invention should not be taken as limiting the scope of the invention, but all equivalent changes or modifications according to the design spirit of the present invention should be considered as falling within the scope of the present invention.
Claims (5)
1. A method for preparing high-purity lithium formate monohydrate by using battery-grade lithium hydroxide monohydrate is characterized by comprising the following steps of: the method comprises the following steps:
A. dissolution of battery grade lithium hydroxide monohydrate: under the normal temperature condition, pouring 200-400 g of battery grade lithium hydroxide monohydrate into a reaction container filled with pure water, and stirring for 10-20 min to obtain a lithium hydroxide solution, wherein the mass liquid-solid ratio of the pure water to the lithium hydroxide monohydrate is 2-3:1;
B. neutralization reaction: slowly pouring lithium hydroxide into the lithium hydroxide solution obtained in the step A under the stirring condition at normal temperature, wherein the molar ratio of the lithium hydroxide is as follows: an industrial formic acid solution with the formic acid of 1:1, wherein the adding rate of the formic acid is 30-50 ml/min, stirring and reacting for 20-40 min, and adjusting the pH value to 7-9 by using lithium hydroxide after the reaction to detect that the pH value is 7-9 without change;
C. filtering and removing impurities: filtering the solution with the pH value of 7-9 obtained in the step B while the solution is hot at normal temperature, and removing alkaline insoluble substances and other impurities to obtain a clear and transparent lithium formate solution;
D. and (3) evaporating and concentrating: c, evaporating and concentrating the clear and transparent lithium formate obtained in the step C, wherein the concentration temperature is 110-120 ℃, and then cooling to 80-90 ℃ to obtain a lithium formate concentrated solution;
E. cooling, crystallizing and filtering: adding 10-20 g of lithium formate monohydrate crystals into the lithium formate concentrated solution obtained in the step D under normal pressure, cooling to 30-50 ℃, at this time, precipitating a large number of lithium formate monohydrate crystals in the lithium formate slurry, and filtering to obtain white needle-shaped lithium formate monohydrate crystals;
F. organic stirring and washing: e, pouring the white needle-shaped lithium formate monohydrate crystal obtained by filtering in the step E into a container filled with 1-2 times of organic solvent with the mass of lithium formate monohydrate, stirring for 20-40 min, and then filtering to obtain the lithium formate monohydrate crystal;
G. vacuum drying: and F, placing the lithium formate monohydrate crystal obtained in the step F into a vacuum drying oven, and drying for 2-4 hours at 25-45 ℃ to obtain the high-purity lithium formate monohydrate.
2. The method for preparing high-purity lithium formate monohydrate by utilizing battery grade lithium hydroxide monohydrate as recited in claim 1, wherein the method comprises the following steps: the mass concentration of the industrial formic acid solution in the step B is 85%.
3. The method for preparing high-purity lithium formate monohydrate by utilizing battery grade lithium hydroxide monohydrate as recited in claim 1, wherein the method comprises the following steps: and C, the solution is alkalescent, and a sand core funnel with a diameter of 3-5um is adopted for filtering.
4. The method for preparing high-purity lithium formate monohydrate by utilizing battery grade lithium hydroxide monohydrate as recited in claim 1, wherein the method comprises the following steps: the organic solvent in the step F is at least one of alcohols, ethers and ketones.
5. The method for preparing high-purity lithium formate monohydrate by utilizing battery grade lithium hydroxide monohydrate as recited in claim 1, wherein the method comprises the following steps: and F, the organic solvent is ethanol, the mass of the ethanol is 1-2 times that of the lithium formate monohydrate, and the stirring is carried out for 20-40 min.
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| Title |
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| 林景臻: "一水甲酸锂单晶的培养", 《福州大学学报》, no. 2, 1 May 1983 (1983-05-01), pages 103 - 108 * |
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