CN114695952A - System and method for producing lithium hexafluorophosphate by dynamic constant temperature crystallization method - Google Patents

System and method for producing lithium hexafluorophosphate by dynamic constant temperature crystallization method Download PDF

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CN114695952A
CN114695952A CN202210454545.4A CN202210454545A CN114695952A CN 114695952 A CN114695952 A CN 114695952A CN 202210454545 A CN202210454545 A CN 202210454545A CN 114695952 A CN114695952 A CN 114695952A
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inlet pipe
mother liquor
lithium fluoride
lithium
reaction
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CN114695952B (en
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石世昆
王成
张周生
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Jiangxi Shi Lei Fluorine Material Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0563—Liquid materials, e.g. for Li-SOCl2 cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/002—Inorganic electrolyte
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    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract

The invention discloses a system for producing lithium hexafluorophosphate by a dynamic constant temperature crystallization method, which belongs to the technical field of lithium battery electrolyte raw material production and comprises a lithium fluoride modulation device, a reaction crystallization device and a mother liquor storage tank, wherein the lithium fluoride modulation device is connected with a first high-purity nitrogen inlet pipe, a lithium fluoride inlet pipe and an anhydrous hydrofluoric acid or mother liquor inlet pipe, a discharge hole of the lithium fluoride modulation device is connected with a reaction crystallization crystal loading feed inlet, and the reaction crystallization device is connected with a mother liquor inlet pipe, a second high-purity nitrogen inlet pipe and a PF (positive-negative-pressure) inlet pipe5The reaction crystallization device comprises a/HCl mixed gas inlet pipe, a discharge port of the reaction crystallization device is connected with a liquid-solid separation device, mother liquor separated in the liquid-solid separation device is conveyed to a mother liquor storage tank through a pipeline, and lithium hexafluorophosphate separated in the liquid-solid separation device is conveyed to a drying device. The present invention is effectiveThe induction period of crystal generation is shortened, the crystallization rate is accelerated, the particle size range of the product is small, and the prepared lithium hexafluorophosphate product has high purity and uniform particle size.

Description

System and method for producing lithium hexafluorophosphate by dynamic constant temperature crystallization method
Technical Field
The invention relates to the technical field of lithium battery electrolyte raw material production, in particular to a system and a method for producing lithium hexafluorophosphate by a dynamic constant temperature crystallization method.
Background
In 1992, Nippon Sony corporation developed a practical lithium ion battery (hereinafter referred to as lithium battery) and introduced it to the market for application in the fields of instruments, telephones, calculators, etc. After 30 years of continuous research, development, improvement, upgrading and market application, the lithium battery becomes the largest family in the field of rechargeable batteries. The application scene is ubiquitous, and the application scene is small, namely the application scene is in the fields of mobile phones, smart phones, tablet computers, notebook computers, instruments and electric tools, and is large, namely the fields of electric bicycles, electric motorcycles, pure electric new energy vehicles, hybrid new energy vehicles, energy storage batteries matched with photovoltaic power generation and wind power generation, and the like.
The lithium battery consists of five parts, namely a positive electrode, a negative electrode, a diaphragm, a current collector and electrolyte. Wherein, each part comprises the following components:
and (3) positive electrode: lithium nickelate, lithium cobaltate, lithium manganate and lithium iron phosphate.
Negative electrode: graphite, and the like.
A diaphragm: polyethylene or polypropylene.
Current collector: the anode is aluminum and the cathode is copper.
Electrolyte solution: the electrolyte consists of an organic solvent and an electrolyte, wherein the organic solvent comprises dimethyl carbonate, methyl ethyl carbonate and the like, and the electrolyte consists of lithium hexafluorophosphate and the like.
Lithium hexafluorophosphate is the most important component of the electrolyte, and the lithium battery completes the charge movement in the battery during the charging and discharging processes. The lithium hexafluorophosphate accounts for twelve percent of the total mass of the electrolyte and accounts for more than eighty percent of the total cost of the electrolyte. The manufacturing cost of lithium hexafluorophosphate directly affects the market price of lithium batteries.
The method for preparing lithium hexafluorophosphate mainly comprises the following steps:
1. and (3) dry method: phosphorus pentafluoride gas reacts directly with solid lithium fluoride crystals, and this method is not a mainstream because it does not use a solvent and cannot stir, and therefore, the reaction rate is low.
2. A solvent method: includes two processes, one is anhydrous hydrofluoric acid process, the other is organic solvent process,
the anhydrous hydrofluoric acid method in the solvent method also comprises a static cooling crystallization method, a dynamic cooling crystallization method and a dynamic constant temperature crystallization method.
The organic solvent method is high in fire prevention management level due to the use of an organic solvent, and the organic solvent can react with phosphorus pentafluoride gas which is one of raw materials for manufacturing lithium hexafluorophosphate to generate colored impurities, so that the quality of finished lithium hexafluorophosphate is influenced.
The static cooling crystallization method in the anhydrous hydrofluoric acid method is the mainstream method at present. The method comprises the steps of crystallizing a synthesized anhydrous hydrofluoric acid solution containing lithium hexafluorophosphate through slow temperature reduction to obtain lithium hexafluorophosphate crystals, drying, crushing and drying the lithium hexafluorophosphate crystals through a solid-liquid separation process to obtain the finished product. The lithium hexafluorophosphate product prepared by the method has stable quality and better indexes. However, the method has the defects of large factory area, large fixed investment, long production period, large power consumption, need of a cryogenic ice machine and high maintenance and management cost of the cryogenic ice machine.
Disclosure of Invention
The invention provides a system and a method for producing lithium hexafluorophosphate by a dynamic constant temperature crystallization method, which solve the problems of large factory building area, large fixed investment, long production period, large power consumption and the like of the conventional mainstream production method of lithium hexafluorophosphate.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
the system for producing lithium hexafluorophosphate by using the dynamic constant temperature crystallization method comprises a lithium fluoride modulation device, a reaction crystallization device and a mother liquor storage tank, wherein the lithium fluoride modulation device is connected with a first high-purity nitrogen inlet pipe, a lithium fluoride inlet pipe and an anhydrous hydrofluoric acid or mother liquor inlet pipe, a discharge port of the lithium fluoride modulation device is connected with a feed port of the reaction crystallization device, the reaction crystallization device is connected with a mother liquor inlet pipe, a second high-purity nitrogen inlet pipe and a PF5A discharge port of the reaction crystallizing device is connected with a liquid-solid separating device, mother liquor separated in the liquid-solid separating device is conveyed to a mother liquor storage tank through a pipeline, and the liquid-solid separating deviceThe lithium hexafluorophosphate crystals separated in (b) are conveyed to a drying device.
Wherein the PF5the/HCl gas inlet pipe extends into the reaction crystallization device, and the PF5The tail end of the/HCl mixed gas inlet pipe is connected with a gas-liquid mixer.
The mother liquor storage tank is connected with a mother liquor circulating pipeline, a first branch of the mother liquor circulating pipeline is communicated with an anhydrous hydrofluoric acid or mother liquor inlet pipe of the lithium fluoride modulation device, and a second branch of the mother liquor circulating pipeline is connected with a mother liquor inlet pipe of the reaction crystallization device.
A method for producing lithium hexafluorophosphate by adopting a system for producing lithium hexafluorophosphate by a dynamic constant temperature crystallization method comprises the following steps:
(1) introducing high-purity nitrogen into a lithium fluoride modulation device through a first high-purity nitrogen inlet pipe, then adding lithium fluoride and anhydrous hydrofluoric acid or mother liquor into the lithium fluoride modulation device through a lithium fluoride inlet pipe and an anhydrous hydrofluoric acid or mother liquor inlet pipe respectively, and stirring uniformly to obtain a hydrogen fluoride solution containing lithium fluoride;
(2) introducing high-purity nitrogen into the reaction crystallization device through a second high-purity nitrogen inlet pipe, and then respectively passing through the feed inlet, the mother liquor pipe and the PF5Adding hydrogen fluoride solution, mother solution and PF of lithium fluoride into a reaction crystallization device by using HCl mixed gas inlet pipe5HCl/mixed gas, PF5Mixing the HCl/gas mixture in a gas-liquid mixer, and PF5Dissolving gas in the mother liquor, controlling the temperature within the range of minus 30 ℃ to plus 20 ℃, and controlling the reaction within 2-20 hours;
(3) and (3) putting the reaction material into a liquid-solid separation device for liquid-solid separation, conveying the liquid after the liquid-solid separation to a mother liquor storage tank for circulation and standby, and conveying the solid to a drying device to obtain the lithium hexafluorophosphate crystal.
Wherein the mass percentage of the lithium fluoride in the hydrogen fluoride solution of the lithium fluoride obtained in the step (1) is 2-20%.
Wherein, after the high-purity nitrogen is introduced, the pressure in the lithium fluoride modulation device is 1.0 to 1.5 bar.
Wherein, after the high-purity nitrogen is introduced, the pressure in the reaction crystallizing device is 1.0 to 1.5 bar.
Wherein, the PF introduced in the step (2)5PF in/HCl mixed gas5And HCl in a volume ratio of 1: 5, the PF5The mol ratio of the lithium fluoride to the lithium fluoride is (1-2) to 1.
Compared with the prior art, the system and the method for producing lithium hexafluorophosphate by using the dynamic constant temperature crystallization method have the following beneficial effects:
1. the reaction device for preparing the lithium hexafluorophosphate crystal and the crystallization device are the same device, and PF (particle Filter) reacted at the upper part of the reaction crystallization device5The gas-dissolved region is formed, and the crystallization is performed in the crystallization region at the lower part of the reaction crystallization device. The existing anhydrous hydrofluoric acid method for producing lithium hexafluorophosphate is carried out in two devices, namely a reaction device and a crystallization device. Compared with the prior art, the production cost is low, and the consumption of anhydrous hydrofluoric acid is low.
2. The mother liquor in the reaction and crystallization device keeps constant temperature, the temperature change is controlled to be plus or minus 5 ℃, and the added mother liquor contains 5 to 20 percent of lithium hexafluorophosphate, so that the induction period of crystal generation can be effectively shortened, the crystallization rate is accelerated, the particle size range of the product is small, and the prepared lithium hexafluorophosphate product has high purity and uniform particle size.
3. The reaction and crystallization of the invention are controlled within 8 hours, while the reaction time of the existing static cooling crystallization method is within 8 hours, and the crystallization time is within 72 hours; the reaction time of the dynamic cooling crystallization method is within 8 hours, the crystallization time is within 36 hours, and compared with the two methods, the production efficiency of the invention is high.
4. Under the condition of the same productivity, the volume of the reaction crystallization device is less than 40 percent of the volume of the static cooling crystallization method reaction and crystallization device and 60 percent of the volume of the dynamic cooling crystallization method reaction and crystallization device respectively.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other embodiments can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic view of a process flow of a system for producing lithium hexafluorophosphate by a dynamic constant temperature crystallization method in the invention.
FIG. 2 is an electron microscope picture of lithium hexafluorophosphate crystals obtained in example 1;
FIG. 3 is an electron microscope picture of lithium hexafluorophosphate crystals obtained in example 2;
FIG. 4 is an electron microscope picture of lithium hexafluorophosphate crystals obtained in example 3;
FIG. 5 is an electron microscope photograph of lithium hexafluorophosphate crystals obtained in example 4.
In the figure: 1. lithium fluoride modulation device, 2 reaction crystallization device, 3 mother liquor storage tank, 4 first high-purity nitrogen inlet pipe, 5 lithium fluoride inlet pipe, 6 anhydrous hydrofluoric acid or mother liquor inlet pipe, 7 mother liquor inlet pipe, 8 second high-purity nitrogen inlet pipe, 9 PF5HCl gas mixture inlet pipe, 10 liquid-solid separator, 11 drier, 12 mother liquid circulating pipeline
Detailed Description
The technical solutions of the present invention will be described clearly and completely through specific embodiments of the present invention in conjunction with the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, the present embodiment provides a system for producing lithium hexafluorophosphate by a dynamic constant temperature crystallization method, which includes a lithium fluoride preparation device 1, a reaction crystallization device 2 and a mother liquor storage tank 3, wherein the lithium fluoride preparation device 1 is connected to a first high purity nitrogen inlet pipe 4, a lithium fluoride inlet pipe 5 and an anhydrous hydrofluoric acid or mother liquor inlet pipe 6, a discharge port of the lithium fluoride preparation device 1 is connected to a reaction crystallization crystal loading feed port, the reaction crystallization device 2 is connected to a mother liquor inlet pipe 7, a second high purity nitrogen inlet pipe 8 and a PF5/HCl mixed gas inlet pipe 9, a discharge port of the reaction crystallization device 2 is connected to a liquid-solid separation device 10, the mother liquor separated in the liquid-solid separation device 10 is conveyed to the mother liquor storage tank 3 through a pipeline, and the lithium hexafluorophosphate separated in the liquid-solid separation device 10 is conveyed to a drying device 11. The lithium fluoride preparation apparatus 1 may be charged with anhydrous hydrofluoric acid or with a mother liquid.
Wherein, the PF5/HCl gas mixture inlet pipe 9 extends into the reaction crystallization device 2, so that the PF5/HCl gas mixture inlet pipe is convenient to be used for leading the PF 899/HCl gas mixture inlet pipe to extend into the reaction crystallization device 25the/HCl mixed gas is dissolved in the gas and reacts with lithium fluoride, and the tail end of the PF5/HCl mixed gas inlet pipe 9 is connected with a gas-liquid mixer.
The mother liquor storage tank 3 is connected with a mother liquor circulation pipeline 12, a first branch of the mother liquor circulation pipeline 12 is communicated with an anhydrous hydrofluoric acid or mother liquor inlet pipe 6 of the lithium fluoride modulation device 1, and a second branch of the mother liquor circulation pipeline 12 is connected with a mother liquor inlet pipe 7 of the reaction crystallization device 2. The mother liquor after separation and crystallization enters the mother liquor storage tank 3 again for the recycling of lithium hexafluorophosphate synthesis. The mother liquor is recycled, so that the production cost is reduced, and the mother liquor contains uncrystallized lithium hexafluorophosphate, so that the induction period of crystal generation can be effectively shortened, and the crystallization rate is accelerated. And because the reaction and crystallization are carried out in the same device, namely the reaction and crystallization temperature are the same, the uniformity of the dynamically generated crystallization is good, and the stirring is carried out in the reaction process, so that the agglomeration is not easy to happen.
Example 1
The embodiment provides a method for producing lithium hexafluorophosphate by a dynamic constant temperature crystallization method, which comprises the following steps:
(1) introducing high-purity nitrogen into a lithium fluoride modulation device through a first high-purity nitrogen inlet pipe, wherein the pressure in the lithium fluoride modulation device is 1.08 bar after the high-purity nitrogen is introduced, then adding lithium fluoride and mother liquor into the lithium fluoride modulation device through a lithium fluoride inlet pipe and an anhydrous hydrofluoric acid or mother liquor inlet pipe respectively, and stirring uniformly to obtain a hydrogen fluoride solution containing lithium fluoride, wherein the mass percentage content of the lithium fluoride is 12%;
(2) introducing high-purity nitrogen into the reaction crystallization device through a second high-purity nitrogen inlet pipe, wherein the pressure in the reaction crystallization device is 1.081 bar after the high-purity nitrogen is introduced, and then respectively passing through the feed inletsMother liquor pipe and PF5Adding hydrogen fluoride solution of lithium fluoride, mother solution and PF into a reaction crystallization device by using/HCl mixed gas inlet pipe5HCl/gas mixture, PF5Mixing the HCl/gas mixture in a gas-liquid mixer, and PF5Dissolving the gas in the mother liquor, controlling the temperature at 0 ℃ and the reaction time at 10 hours; wherein the introduced PF5PF in/HCl mixed gas5And HCl in a volume ratio of 1: 5, the PF5The mol ratio of the lithium fluoride to the lithium fluoride is 1.05: 1;
(3) and (3) putting the reaction material into a liquid-solid separation device for liquid-solid separation, conveying the liquid after the liquid-solid separation to a mother liquor storage tank for circulation and standby, and conveying the solid to a drying device to obtain the lithium hexafluorophosphate crystal.
The drying in the step (3) of the implementation adopts nitrogen protection vacuum drying, the drying temperature is 60 ℃, and the drying time is 2 hours.
In this example, the lithium hexafluorophosphate content in the mother liquor added to the lithium fluoride preparation apparatus and the reaction crystallization apparatus was 10% by mass. The amount of the mother liquor added to the reaction crystallizer was 1.4 times the amount added to the lithium fluoride preparation apparatus.
The yield of the product of the invention is 100% based on lithium fluoride, and an electron microscope picture of lithium hexafluorophosphate prepared in this example is shown in fig. 1. The strong lithium hexafluorophosphate crystals prepared in this example were analyzed and the results are as follows:
the purity of the product was 99.96%, the free acid (HF) was 90ppm, and the moisture content (in terms of H) was 90ppm2Calculated as O) was 15 ppm.
Example 2
The embodiment provides a method for producing lithium hexafluorophosphate by a dynamic constant temperature crystallization method, which comprises the following steps:
(1) introducing high-purity nitrogen into a lithium fluoride modulation device through a first high-purity nitrogen inlet pipe, wherein the pressure in the lithium fluoride modulation device is 1.05 bar after the high-purity nitrogen is introduced, then adding lithium fluoride and anhydrous hydrofluoric acid or mother liquor into the lithium fluoride modulation device through a lithium fluoride inlet pipe and an anhydrous hydrofluoric acid or mother liquor inlet pipe respectively, and stirring uniformly to obtain a hydrogen fluoride solution containing lithium fluoride, wherein the mass percentage content of the lithium fluoride is 15%;
(2) introducing high-purity nitrogen into a reaction crystallization device through a second high-purity nitrogen inlet pipe, wherein the pressure in the reaction crystallization device is 1.051 bar after the high-purity nitrogen is introduced, and then respectively passing through a feed inlet, a mother liquor pipe and a PF5Adding hydrogen fluoride solution, mother solution and PF of lithium fluoride into a reaction crystallization device by using HCl mixed gas inlet pipe5HCl/mixed gas, PF5Mixing the HCl/gas mixture in a gas-liquid mixer, and PF5Dissolving the gas in the mother liquor, controlling the temperature at-30 ℃ and the reaction time at 20 hours; wherein the introduced PF5PF in/HCl mixed gas5And HCl in a volume ratio of 1: 5, the PF5The mol ratio of the lithium fluoride to the lithium fluoride is 1.10: 1;
(3) and (3) putting the reaction material into a liquid-solid separation device for liquid-solid separation, conveying the liquid after the liquid-solid separation to a mother liquor storage tank for circulation and standby, and conveying the solid to a drying device to obtain the lithium hexafluorophosphate crystal.
The drying in the step (3) is carried out under the protection of nitrogen and in vacuum, the drying temperature is 60 ℃, and the drying time is 2 hours.
In this example, the mass percentage content of lithium hexafluorophosphate in the mother liquor added to the lithium fluoride preparation apparatus and the reaction crystallization apparatus was 5%. The amount of the mother liquor added to the reaction crystallizer was 1.5 times the amount added to the lithium fluoride preparation apparatus.
The yield of the product of the invention is 100% calculated by lithium fluoride, and an electron microscope picture of the lithium hexafluorophosphate prepared in the embodiment is shown in fig. 2. The strong lithium hexafluorophosphate crystals prepared in this example were analyzed and the results are as follows:
the purity of the product was 99.95%, the free acid (HF) was 80ppm, and the water content (in terms of H) was 80ppm2Calculated as O) was 18 ppm.
Example 3
The embodiment provides a method for producing lithium hexafluorophosphate by a dynamic constant temperature crystallization method, which comprises the following steps:
(1) introducing high-purity nitrogen into a lithium fluoride modulation device through a first high-purity nitrogen inlet pipe, wherein the pressure in the lithium fluoride modulation device is 1.1 bar after the high-purity nitrogen is introduced, then adding lithium fluoride and anhydrous hydrofluoric acid or mother liquor into the lithium fluoride modulation device through a lithium fluoride inlet pipe and an anhydrous hydrofluoric acid or mother liquor inlet pipe respectively, and stirring uniformly to obtain a hydrogen fluoride solution containing lithium fluoride, wherein the mass percentage content of the lithium fluoride is 10%;
(2) introducing high-purity nitrogen into the reaction crystallization device through a second high-purity nitrogen inlet pipe, wherein the pressure in the reaction crystallization device is 1.1 bar after the high-purity nitrogen is introduced, and then respectively passing through the feed inlet, the mother liquor pipe and the PF5Adding hydrogen fluoride solution of lithium fluoride, mother solution and PF into a reaction crystallization device by using/HCl mixed gas inlet pipe5HCl/mixed gas, PF5Mixing the HCl/gas mixture in a gas-liquid mixer, and PF5Dissolving the gas in the mother liquor, controlling the temperature at 20 ℃ and the reaction time at 2 hours; wherein the introduced PF5PF in/HCl mixed gas5And HCl in a volume ratio of 1: 5, the PF5The mol ratio of the lithium fluoride to the lithium fluoride is 1.05: 1;
(3) and (3) putting the reaction material into a liquid-solid separation device for liquid-solid separation, conveying the liquid after the liquid-solid separation to a mother liquor storage tank for circulation and standby, and conveying the solid to a drying device to obtain the lithium hexafluorophosphate crystal.
The drying in the step (3) of the implementation adopts nitrogen protection vacuum drying, the drying temperature is 60 ℃, and the drying time is 2 hours.
In the present example, the mass percentage content of lithium hexafluorophosphate in the mother liquor added to the lithium fluoride preparation apparatus and the reaction crystallization apparatus was 20%. The amount of the mother liquor added to the reaction crystallizer was 1.2 times the amount added to the lithium fluoride preparation apparatus.
The yield of the product of the invention is 100% calculated by lithium fluoride, and an electron microscope picture of the lithium hexafluorophosphate prepared in the embodiment is shown in fig. 3. The strong lithium hexafluorophosphate crystals prepared in this example were analyzed and the results are as follows:
the purity of the product was 99.97%, the free acid (HF) was 100ppm, and the water content (in terms of H) was 100ppm2Calculated as O) was 10 ppm.
Example 4
The embodiment provides a method for producing lithium hexafluorophosphate by a dynamic constant temperature crystallization method, which comprises the following steps:
(1) introducing high-purity nitrogen into a lithium fluoride modulation device through a first high-purity nitrogen inlet pipe, wherein the pressure in the lithium fluoride modulation device is 1.06 bar after the high-purity nitrogen is introduced, then adding lithium fluoride and anhydrous hydrofluoric acid into the lithium fluoride modulation device through a lithium fluoride inlet pipe and an anhydrous hydrofluoric acid or mother liquor inlet pipe respectively, and stirring uniformly to obtain a hydrogen fluoride solution containing lithium fluoride, wherein the mass percentage content of the lithium fluoride is 14%;
(2) introducing high-purity nitrogen into the reaction crystallization device through a second high-purity nitrogen inlet pipe, wherein the pressure in the reaction crystallization device is 1.08 bar after the high-purity nitrogen is introduced, and then respectively passing through a feed inlet, a mother liquor pipe and a PF5Adding hydrogen fluoride solution, mother solution and PF of lithium fluoride into a reaction crystallization device by using HCl mixed gas inlet pipe5HCl/mixed gas, PF5Mixing the HCl/gas mixture in a gas-liquid mixer, and PF5Dissolving the gas in the mother liquor, controlling the temperature at-10 ℃ and the reaction time at 8 hours; wherein the introduced PF5PF in/HCl mixed gas5And HCl in a volume ratio of 1: 5, the PF5The mol ratio of the lithium fluoride to the lithium fluoride is 1.09: 1;
(3) and (3) putting the reaction material into a liquid-solid separation device for liquid-solid separation, conveying the liquid after the liquid-solid separation to a mother liquor storage tank for circulation and standby, and conveying the solid to a drying device to obtain the lithium hexafluorophosphate crystal.
The drying in the step (3) of the implementation adopts nitrogen protection vacuum drying, the drying temperature is 60 ℃, and the drying time is 2 hours.
In the present example, the mass percentage content of lithium hexafluorophosphate in the mother liquor added to the lithium fluoride preparation apparatus and the reaction crystallization apparatus was 14%. The amount of the mother liquor added to the reaction crystallization apparatus was 1.3 times the amount of the anhydrous hydrofluoric acid added to the lithium fluoride preparation apparatus.
The yield of the product of the invention is 99.2% calculated by lithium fluoride, and an electron microscope picture of the lithium hexafluorophosphate prepared in the embodiment is shown in fig. 4. The strong lithium hexafluorophosphate crystals prepared in this example were analyzed and the results are as follows:
the purity of the product was 99.97%, the free acid (HF) was 80ppm, and the moisture content (in terms of H) was 80ppm2Calculated as O) was 12 ppm.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (8)

1. The system for producing lithium hexafluorophosphate by using the dynamic constant temperature crystallization method is characterized by comprising a lithium fluoride modulation device, a reaction crystallization device and a mother liquor storage tank, wherein the lithium fluoride modulation device is connected with a first high-purity nitrogen inlet pipe, a lithium fluoride inlet pipe and an anhydrous hydrofluoric acid or mother liquor inlet pipe, a discharge port of the lithium fluoride modulation device is connected with a feed port of the reaction crystallization device, and the reaction crystallization device is connected with a mother liquor inlet pipe, a second high-purity nitrogen inlet pipe and a PF (positive-negative-pressure reactor)5The reaction crystallization device comprises a/HCl mixed gas inlet pipe, a discharge port of the reaction crystallization device is connected with a liquid-solid separation device, mother liquor separated in the liquid-solid separation device is conveyed to a mother liquor storage tank through a pipeline, and lithium hexafluorophosphate crystals separated in the liquid-solid separation device are conveyed to a drying device.
2. The system for producing lithium hexafluorophosphate by using dynamic constant temperature crystallization method according to claim 1, wherein: the PF5the/HCl gas inlet pipe extends into the reaction crystallization device, and the PF5The tail end of the/HCl mixed gas inlet pipe is connected with a gas-liquid mixer.
3. The system for producing lithium hexafluorophosphate by using dynamic constant temperature crystallization method according to claim 1, wherein: the mother liquor storage tank is connected with a mother liquor circulating pipeline, a first branch of the mother liquor circulating pipeline is communicated with an anhydrous hydrofluoric acid or mother liquor inlet pipe of the lithium fluoride modulation device, and a second branch of the mother liquor circulating pipeline is connected with a mother liquor inlet pipe of the reaction crystallization device.
4. A method for producing lithium hexafluorophosphate using the system for producing lithium hexafluorophosphate by the dynamic isothermal crystallization method according to any one of claims 1 to 3, characterized by comprising the steps of:
(1) introducing high-purity nitrogen into a lithium fluoride modulation device through a first high-purity nitrogen inlet pipe, then adding lithium fluoride and anhydrous hydrofluoric acid or mother liquor into the lithium fluoride modulation device through a lithium fluoride inlet pipe and an anhydrous hydrofluoric acid or mother liquor inlet pipe respectively, and stirring uniformly to obtain a hydrogen fluoride solution containing lithium fluoride;
(2) introducing high-purity nitrogen into the reaction crystallization device through a second high-purity nitrogen inlet pipe, and then respectively passing through the feed inlet, the mother liquor pipe and the PF5Adding hydrogen fluoride solution of lithium fluoride, mother solution and PF into a reaction crystallization device by using/HCl mixed gas inlet pipe5HCl/gas mixture, PF5Mixing the HCl/gas mixture in a gas-liquid mixer, and PF5Dissolving gas in the mother liquor, controlling the temperature within the range of minus 30 ℃ to plus 20 ℃, and controlling the reaction within 2-20 hours;
(3) and (3) putting the reaction material into a liquid-solid separation device for liquid-solid separation, conveying the liquid after the liquid-solid separation to a mother liquor storage tank for circulation and standby, and conveying the solid to a drying device to obtain the lithium hexafluorophosphate crystal.
5. The method for producing lithium hexafluorophosphate of claim 4, wherein: the mass percentage of the lithium fluoride in the hydrogen fluoride solution of the lithium fluoride obtained in the step (1) is 2-20%.
6. The method for producing lithium hexafluorophosphate according to claim 4, wherein: after the introduction of high-purity nitrogen, the pressure in the lithium fluoride preparation apparatus was 1.0 to 1.5 bar.
7. The method for producing lithium hexafluorophosphate according to claim 1, wherein: after introducing high-purity nitrogen, the pressure in the reaction crystallization device is 1.0 to 1.5 bar.
8. The method for producing lithium hexafluorophosphate according to claim 1, wherein: PF introduced in the step (2)5PF in/HCl mixed gas5And HCl in a volume ratio of 1: 5, the PF5The mol ratio of the lithium fluoride to the lithium fluoride is (1-2) to 1.
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CN102515133A (en) * 2011-12-31 2012-06-27 东莞市东骏新能源科技有限公司 Preparation method of lithium hexafluorophosphate of lithium ion battery electrolyte
CN105600809A (en) * 2016-02-25 2016-05-25 多氟多化工股份有限公司 Method and device for preparing lithium hexafluorophosphate through dynamic crystallization
CN110683562A (en) * 2019-12-10 2020-01-14 中化蓝天集团有限公司 Continuous production system of lithium hexafluorophosphate
CN112340754A (en) * 2019-08-09 2021-02-09 惠州比亚迪电池有限公司 Lithium hexafluorophosphate, crystallization and preparation method thereof, lithium ion battery electrolyte and lithium ion battery
CN112678850A (en) * 2020-12-30 2021-04-20 徐兴碧 Production device and method of lithium hexafluorophosphate

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CN1339401A (en) * 2001-09-25 2002-03-13 天津化工研究设计院 Method for preparing lithium hexafluorophosphate
CN102515133A (en) * 2011-12-31 2012-06-27 东莞市东骏新能源科技有限公司 Preparation method of lithium hexafluorophosphate of lithium ion battery electrolyte
CN105600809A (en) * 2016-02-25 2016-05-25 多氟多化工股份有限公司 Method and device for preparing lithium hexafluorophosphate through dynamic crystallization
CN112340754A (en) * 2019-08-09 2021-02-09 惠州比亚迪电池有限公司 Lithium hexafluorophosphate, crystallization and preparation method thereof, lithium ion battery electrolyte and lithium ion battery
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