CN118255368A - Method for preparing lithium hexafluorophosphate by lithium-containing aluminum electrolyte - Google Patents
Method for preparing lithium hexafluorophosphate by lithium-containing aluminum electrolyte Download PDFInfo
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- CN118255368A CN118255368A CN202410385261.3A CN202410385261A CN118255368A CN 118255368 A CN118255368 A CN 118255368A CN 202410385261 A CN202410385261 A CN 202410385261A CN 118255368 A CN118255368 A CN 118255368A
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 70
- -1 lithium hexafluorophosphate Chemical compound 0.000 title claims abstract description 59
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 42
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 42
- 238000000034 method Methods 0.000 title claims abstract description 36
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 31
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 30
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 68
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 53
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 37
- 239000002002 slurry Substances 0.000 claims abstract description 33
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 31
- 150000003839 salts Chemical class 0.000 claims abstract description 31
- 239000002904 solvent Substances 0.000 claims abstract description 31
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 21
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 18
- 239000000706 filtrate Substances 0.000 claims abstract description 18
- 239000011259 mixed solution Substances 0.000 claims abstract description 16
- 238000002156 mixing Methods 0.000 claims abstract description 16
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000001816 cooling Methods 0.000 claims abstract description 10
- 238000001914 filtration Methods 0.000 claims abstract description 10
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims abstract description 7
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 6
- 230000003472 neutralizing effect Effects 0.000 claims abstract description 6
- 238000001035 drying Methods 0.000 claims description 19
- 239000003463 adsorbent Substances 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 239000002808 molecular sieve Substances 0.000 claims description 4
- 239000000741 silica gel Substances 0.000 claims description 4
- 229910002027 silica gel Inorganic materials 0.000 claims description 4
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 4
- 230000007935 neutral effect Effects 0.000 claims description 3
- 235000019441 ethanol Nutrition 0.000 description 20
- 238000006243 chemical reaction Methods 0.000 description 19
- 239000000243 solution Substances 0.000 description 11
- 229910019142 PO4 Inorganic materials 0.000 description 10
- 229910001610 cryolite Inorganic materials 0.000 description 8
- 230000008569 process Effects 0.000 description 8
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 6
- 229910001416 lithium ion Inorganic materials 0.000 description 6
- 239000012046 mixed solvent Substances 0.000 description 6
- 239000011734 sodium Substances 0.000 description 6
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 description 6
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 6
- IRPGOXJVTQTAAN-UHFFFAOYSA-N 2,2,3,3,3-pentafluoropropanal Chemical compound FC(F)(F)C(F)(F)C=O IRPGOXJVTQTAAN-UHFFFAOYSA-N 0.000 description 4
- KLZUFWVZNOTSEM-UHFFFAOYSA-K Aluminum fluoride Inorganic materials F[Al](F)F KLZUFWVZNOTSEM-UHFFFAOYSA-K 0.000 description 4
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 4
- 230000009471 action Effects 0.000 description 4
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 4
- 229910052808 lithium carbonate Inorganic materials 0.000 description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 4
- 238000001179 sorption measurement Methods 0.000 description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- ILRRQNADMUWWFW-UHFFFAOYSA-K aluminium phosphate Chemical compound O1[Al]2OP1(=O)O2 ILRRQNADMUWWFW-UHFFFAOYSA-K 0.000 description 3
- 239000003546 flue gas Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 239000011775 sodium fluoride Substances 0.000 description 3
- 235000013024 sodium fluoride Nutrition 0.000 description 3
- 229910000162 sodium phosphate Inorganic materials 0.000 description 3
- 239000001488 sodium phosphate Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 229910000406 trisodium phosphate Inorganic materials 0.000 description 3
- 229910004261 CaF 2 Inorganic materials 0.000 description 2
- 238000009626 Hall-Héroult process Methods 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000001476 alcoholic effect Effects 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 229910017119 AlPO Inorganic materials 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- 229910020826 NaAlF6 Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 229940021013 electrolyte solution Drugs 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 229910001386 lithium phosphate Inorganic materials 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 229910052566 spinel group Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 description 1
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- Secondary Cells (AREA)
Abstract
The present application relates to a method for preparing lithium hexafluorophosphate by a lithium-containing aluminum electrolyte, comprising the steps of: providing a mixed solution comprising phosphoric acid and an alcohol solvent; providing a lithium-containing cryolite-alumina molten salt electrolyte, mixing the cryolite-alumina molten salt electrolyte with the mixed solution, and reacting for a preset time at a first temperature to obtain slurry; adding a neutralizing agent into the slurry to perform a neutralization reaction until the acid-base property of the slurry reaches neutrality; cooling the slurry to a second temperature, removing water in the slurry, filtering and collecting filtrate, and removing solvent in the filtrate to obtain lithium hexafluorophosphate, wherein the neutralizing agent is at least one of sodium hydroxide and aluminum hydroxide, and the alcohol solvent is at least one of methanol and ethanol. The application has the advantages of simple flow and low cost.
Description
Technical Field
The application relates to the field of aluminum electrolysis, in particular to an aluminum electrolyte.
Background
In the production of Hall-Heroult process (Hall-Heroult process) electrolytic aluminum, a cryolite-alumina molten salt electrolytic method is adopted, cryolite is electrolyte, alumina is molten, after strong direct current is introduced, electrochemical reaction is carried out on two poles in an electrolytic tank, and lithium-containing aluminum electrolyte can be used as a part of the electrolyte, so that the melting point is reduced, the conductivity is improved, and the energy consumption and the production efficiency are reduced. The lithium in the cell electrolyte is mainly from two sources, namely, additional lithium fluoride and lithium carried by alumina, and the lithium is mainly in the form of lithium-containing aluminum electrolyte (LiNa 2AlF6) in the electrolyte.
In recent years, with the increase of lithium carbonate price, lithium in the electrolyte is paid more attention to, and currently, lithium in the surplus aluminum electrolyte is basically prepared into lithium carbonate by extraction and recovery, fluoride is converted into spinels or aluminum fluoride, and mixed salts such as sodium salt, potassium salt and the like are generated in the process. At present, the methods often involve procedures of roasting, acid leaching, impurity removal and the like, the extraction flow is long, lithium carbonate is usually used as a raw material of lithium ion battery electrolyte, the lithium carbonate is prepared into the lithium ion battery electrolyte, and the lithium ion battery electrolyte is required to be prepared through a complex flow.
Disclosure of Invention
The embodiment of the application provides a method for preparing lithium hexafluorophosphate by using a lithium-containing aluminum electrolyte, which aims to solve the technical problems of complex flow and high cost of preparing lithium in a surplus aluminum electrolyte into an electrolyte of a lithium ion battery.
The embodiment of the application provides a method for preparing lithium hexafluorophosphate by a lithium-containing aluminum electrolyte, which comprises the following steps of:
Providing a mixed solution comprising phosphoric acid and an alcohol solvent;
Providing a lithium-containing cryolite-alumina molten salt electrolyte, mixing the cryolite-alumina molten salt electrolyte with the mixed solution, and reacting for a preset time at a first temperature to obtain slurry;
adding a neutralizing agent into the slurry to perform a neutralization reaction until the pH of the slurry reaches neutral;
Cooling the slurry to a second temperature, removing water in the slurry, filtering and collecting filtrate, removing solvent in the filtrate to obtain lithium hexafluorophosphate,
Wherein the neutralizer is at least one of sodium hydroxide and aluminum hydroxide, and the alcohol solvent is at least one of methanol and ethanol.
In some embodiments of the application, the phosphoric acid is added in an amount of 1.2 to 2 times the theoretical amount that would just allow the cryolite-alumina molten salt electrolyte to react completely.
In some embodiments of the application, the providing a mixed solution comprising phosphoric acid, an alcoholic solvent, comprises: mixing concentrated phosphoric acid and an alcohol solvent to obtain a mixed solution, wherein the volume ratio of the alcohol solvent to the concentrated phosphoric acid is 3-20:1.
In some embodiments of the application, the first temperature is 60 to 200 ℃.
In some embodiments of the application, the predetermined time is 1 to 24 hours.
In some embodiments of the application, the neutralization reaction is 30 to 90 minutes in duration.
In some embodiments of the application, the second temperature is between 0 and 30 ℃.
In some embodiments of the application, the removing of the moisture in the slurry is performed by removing the moisture in the slurry with an adsorbent material.
In some embodiments of the application, the adsorbent material is at least one of molecular sieve, silica gel, activated carbon.
In some embodiments of the application, the removing the solvent from the filtrate comprises the steps of:
And (3) drying the filtrate at a low temperature of between 10 and 30 ℃.
Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:
According to the method for preparing lithium hexafluorophosphate by the lithium-containing aluminum electrolyte, the mixed solution comprising phosphoric acid and an alcohol solvent is used as a reaction place, so that cryolite-aluminum oxide molten salt electrolyte reacts with phosphoric acid, and lithium hexafluorophosphate is enriched into a solution state by utilizing the dissolution behavior characteristic of a product in the alcohol solvent, and the whole process only comprises the operations of reaction, neutralization, water removal, filtration and the like, so that the lithium hexafluorophosphate can be obtained, and the method is simple in flow, low in consumption, and high in conversion rate and purity of the lithium hexafluorophosphate.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.
In order to more clearly illustrate the embodiments of the application or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.
Fig. 1 is a schematic flow chart of a method for preparing lithium hexafluorophosphate by using a lithium-containing aluminum electrolyte according to an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
Unless specifically stated otherwise, the terms used herein should be understood as meaning as commonly used in the art. Accordingly, 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 application belongs. In case of conflict, the present specification will control.
Unless otherwise specifically indicated, the various raw materials, reagents, instruments, equipment and the like used in the present application are commercially available or may be prepared by existing methods.
At present, the lithium in the surplus aluminum electrolyte is prepared into the electrolyte of the lithium ion battery, and the technical problems of complex flow and high cost exist.
The technical scheme provided by the embodiment of the application aims to solve the technical problems, and the overall thought is as follows:
The embodiment of the application provides a method for preparing lithium hexafluorophosphate by a lithium-containing aluminum electrolyte, which comprises the following steps of:
s1: providing a mixed solution comprising phosphoric acid and an alcohol solvent;
S2: providing a lithium-containing cryolite-alumina molten salt electrolyte, mixing the cryolite-alumina molten salt electrolyte with the mixed solution, and reacting for a preset time at a first temperature to obtain slurry;
S3: adding a neutralizing agent into the slurry to perform a neutralization reaction until the pH of the slurry reaches neutral;
S4: cooling the slurry to a second temperature, removing water in the slurry, filtering and collecting filtrate, removing solvent in the filtrate to obtain lithium hexafluorophosphate,
Wherein the neutralizer is at least one of sodium hydroxide and aluminum hydroxide, and the alcohol solvent is at least one of methanol and ethanol.
Those skilled in the art will appreciate that the cryolite-alumina molten salt electrolyte primarily includes Na 3AlF6 and LiNa 2AlF6.
The main chemical change in the step S2 is that cryolite is decomposed under the action of acid to generate hydrofluoric acid and phosphate; hydrofluoric acid reacts with phosphate ions to form hexafluorophosphate. The following reaction can be considered to occur:
Na3AlF6+2H3PO4＝Na3PO4+AlPO4+6HF
3LiNa2AlF6+6H3PO4＝2Na3PO4+Li3PO4+3AlPO4+18HF
PO4 3-+6HF+2H+＝PF6 -+4H2O
The step S3 is to add a neutralizer to convert the redundant phosphoric acid into Na 3PO4 or AlPO 4 to enter a solid phase, eliminate the influence of phosphate ions on the purity of lithium hexafluorophosphate, and further improve the purity of the finally obtained lithium hexafluorophosphate.
The products in the whole process comprise sodium phosphate, aluminum phosphate, sodium fluoride, aluminum fluoride and lithium hexafluorophosphate. Wherein sodium phosphate, aluminum phosphate, sodium fluoride, aluminum fluoride are insoluble in methanol, ethanol, and lithium hexafluorophosphate is soluble in methanol or ethanol. After the solution reaches neutrality in step S3 and the water is removed in step S4, the solvent in the slurry is at least one of methanol or ethanol, sodium ions, aluminum ions, phosphate ions, fluoride ions are all deposited in a precipitated form, and lithium hexafluorophosphate can exist in a dissolved state and is finally separated by filtration.
Thus, taking the example that the neutralizing agent comprises sodium hydroxide and aluminum hydroxide at the same time, the following chemical reaction can be considered to occur in the whole process:
One (I) ：3LiNa2AlF6+8H3PO4＝2Na3PO4+3AlPO4+3LiPF6+12H2O
Two kinds of ：Na3AlF6+2H3PO4+6NaOH＝Na3PO4+AlPO4+6NaF+6H2O
Three kinds of ：Na3AlF6+2H3PO4+2Al(OH)3＝Na3PO4+AlPO4+2AlF3+6H2O
As will be appreciated by those skilled in the art, lithium hexafluorophosphate is a widely used solute in lithium ion battery electrolyte solutions.
According to the application, the mixed solution comprising phosphoric acid and an alcohol solvent is used as a reaction place, cryolite-alumina molten salt electrolyte reacts with phosphoric acid, and lithium hexafluorophosphate is enriched into a solution state by utilizing the dissolution behavior characteristic of a product in the alcohol solvent, and the whole process only comprises the operations of reaction, neutralization, water removal, filtration and the like, so that lithium hexafluorophosphate can be obtained, and the flow is simple, the consumption is low, and the conversion rate and purity of the lithium hexafluorophosphate are high.
The conversion rate of lithium into lithium hexafluorophosphate is more than 95%, and the purity of the prepared lithium hexafluorophosphate is more than 99%.
In some embodiments of the application, the phosphoric acid is added in an amount of 1.2 to 2 times the theoretical amount that would just allow the cryolite-alumina molten salt electrolyte to react completely.
It is easy to understand that the theoretical amount is calculated according to the formula one, the formula two and the formula three. Before the application is implemented, the respective contents of LiNa 2AlF6 and Na 3AlF6 in the cryolite-alumina molten salt electrolyte can be calculated in advance, and then the theoretical amount of phosphoric acid which enables the cryolite-alumina molten salt electrolyte to completely react can be calculated.
As an example, the phosphoric acid may be added in an amount of 1.2 times, 1.4 times, 1.5 times, 1.8 times, 2 times the theoretical amount that just causes the cryolite-alumina molten salt electrolyte to fully react.
In some embodiments of the application, the providing a mixed solution comprising phosphoric acid, an alcoholic solvent, comprises: mixing concentrated phosphoric acid and an alcohol solvent to obtain a mixed solution, wherein the volume ratio of the alcohol solvent to the concentrated phosphoric acid is 3-20:1.
The volume ratio of the alcohol solvent to the concentrated phosphoric acid is 3-20:1, and the sufficient phosphoric acid solution can fully ionize reactants, so that the reaction efficiency is improved, and meanwhile, sufficient alcohol exists, so that the generated lithium hexafluorophosphate is fully dissolved into the solution, and sodium phosphate, aluminum phosphate, sodium fluoride and aluminum fluoride are fully precipitated.
In some embodiments of the application, the first temperature is 60 to 200 ℃.
The first temperature is 60-200 ℃, and the beneficial effect is that reactants can be fully reacted.
As an example, the first temperature may be 60 ℃, 80 ℃, 120 ℃, 150 ℃, 200 ℃.
In some embodiments of the application, the predetermined time is 1 to 24 hours.
The first temperature rise is advantageous for an increase in reaction efficiency, and the predetermined time is adjustable with temperature.
In some embodiments of the application, the neutralization reaction is 30 to 90 minutes in duration.
As an example, the duration of the neutralization reaction may be 30min, 50min, 70min, 90min.
In some embodiments of the application, the second temperature is 0-30 ℃, while avoiding decomposition of lithium hexafluorophosphate and improving conversion of lithium hexafluorophosphate.
As an example, the second temperature may be 0 ℃,5 ℃, 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃.
In some embodiments of the application, the removing of the moisture in the slurry is performed by removing the moisture in the slurry with an adsorbent material.
In addition, when the water in the slurry is removed by the adsorbent, the adsorption efficiency is high when the second temperature is 0 to 30 ℃.
In some embodiments of the application, the adsorbent material is at least one of a molecular sieve, a silica gel.
In some embodiments of the application, the removing the solvent from the filtrate comprises the steps of:
S41: and (3) drying the filtrate at a low temperature of between 10 and 30 ℃.
Mist can be collected in the low-temperature drying process to obtain an alcohol solvent which can be recycled; the low-temperature drying process can adopt vacuumizing operation, so that the low-temperature drying efficiency is improved; meanwhile, the lithium hexafluorophosphate generated by low-temperature drying can be effectively prevented from being decomposed, and the conversion rate is improved.
The application will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present application and are not intended to limit the scope of the present application. The experimental procedures, which are not specified in the following examples, are generally determined according to industry standards. If there is no corresponding industry standard, it is carried out according to the general international standard, the conventional conditions, or according to the conditions recommended by the manufacturer.
Example 1
The present embodiment provides a method for preparing lithium hexafluorophosphate by a lithium-containing aluminum electrolyte, comprising the steps of:
Providing a lithium-containing cryolite-alumina molten salt electrolyte, measuring and calculating the components of the cryolite-alumina molten salt electrolyte, wherein the content of Na 3AlF6 is 54.6wt%, the content of LiNa 2AlF6 is 40.5wt%, the content of CaF 2 is 2.8wt% and the content of alpha-Al 2O3 is 2.1wt% based on the weight percentage of the cryolite-alumina molten salt electrolyte;
Mixing concentrated phosphoric acid and absolute ethyl alcohol, wherein the addition amount of the concentrated phosphoric acid is 1.2 times of the theoretical value of complete reaction with cryolite, and the volume ratio of the absolute ethyl alcohol to the concentrated phosphoric acid is 3:1, and uniformly mixing to obtain a mixed solvent;
Mixing cryolite-alumina molten salt electrolyte with a mixed solvent, reacting for 24 hours at 60 ℃, adding a neutralizer sodium hydroxide for neutralization reaction to obtain slurry, wherein the reaction time is 30min;
Cooling the slurry to 30 ℃, carrying out water adsorption by using a molecular sieve, filtering, drying the filtrate at a low temperature by using an absolute ethyl alcohol solution of saturated lithium hexafluorophosphate, controlling the low-temperature drying temperature at 30 ℃, and cooling and collecting flue gas in the drying process to obtain absolute ethyl alcohol for recycling, wherein the solid after low-temperature drying is lithium hexafluorophosphate.
The conversion rate of lithium in the electrolyte into lithium hexafluorophosphate was 95%, and the purity of the prepared lithium hexafluorophosphate was 99%.
Example 2
The present embodiment provides a method for preparing lithium hexafluorophosphate by a lithium-containing aluminum electrolyte, comprising the steps of:
Providing a lithium-containing cryolite-alumina molten salt electrolyte, measuring and calculating the components of the cryolite-alumina molten salt electrolyte, wherein the content of Na 3AlF6 is 61.4wt%, the content of LiNa 2AlF6 is 32.5wt%, the content of CaF 2 is 3.2wt% and the content of alpha-Al 2O3 is 2.9wt% based on the weight percentage of the cryolite-alumina molten salt electrolyte;
Mixing concentrated phosphoric acid and absolute ethyl alcohol, wherein the addition amount of the concentrated phosphoric acid is 1.6 times of the theoretical value of complete reaction with cryolite, the volume ratio of the absolute ethyl alcohol to the concentrated phosphoric acid is 12:1, and uniformly mixing to obtain a mixed solvent;
Mixing cryolite-alumina molten salt electrolyte with a mixed solvent, reacting for 12 hours at 120 ℃, adding a neutralizer aluminum hydroxide, and carrying out neutralization reaction to obtain slurry, wherein the reaction time is 60 minutes;
Cooling the slurry to 15 ℃, carrying out water adsorption by adopting silica gel, filtering, carrying out low-temperature drying on the filtrate which is an absolute ethanol solution of saturated lithium hexafluorophosphate, controlling the low-temperature drying temperature at 20 ℃, and cooling and collecting flue gas in the drying process to obtain absolute ethanol for recycling, wherein the solid after low-temperature drying is lithium hexafluorophosphate.
The conversion rate of lithium in the electrolyte into lithium hexafluorophosphate was 96.2%, and the purity of the prepared lithium hexafluorophosphate was 99%.
Example 3
The present embodiment provides a method for preparing lithium hexafluorophosphate by a lithium-containing aluminum electrolyte, comprising the steps of:
Providing a lithium-containing cryolite-alumina molten salt electrolyte, measuring and calculating the components of the cryolite-alumina molten salt electrolyte, wherein the content of Na 3AlF6 is 70.6wt% and the content of LiNa 2AlF6 is 24.2wt% measured by the weight percentage of the cryolite-alumina molten salt electrolyte; caF 2 accounts for 2.2wt%, alpha-Al 2O3 accounts for 1.2wt%, and K 2NaAlF6 accounts for 1.8wt%;
mixing concentrated phosphoric acid and absolute ethyl alcohol, wherein the addition amount of the concentrated phosphoric acid is 2.0 times of the theoretical value of complete reaction with cryolite, the volume ratio of the absolute ethyl alcohol to the concentrated phosphoric acid is 20:1, and uniformly mixing to obtain a mixed solvent;
Mixing cryolite-alumina molten salt electrolyte with a mixed solvent, reacting for 1h at 200 ℃, adding a neutralizer aluminum hydroxide, and carrying out neutralization reaction to obtain slurry, wherein the reaction time is 90min;
Cooling the slurry to 0 ℃, carrying out water adsorption by adopting active carbon, filtering, wherein the filtrate is an absolute ethanol solution of saturated lithium hexafluorophosphate, drying the filtrate at a low temperature, controlling the low temperature drying temperature to be 10 ℃, and cooling and collecting flue gas in the drying process to obtain absolute ethanol for recycling, wherein the solid after low temperature drying is lithium hexafluorophosphate.
The conversion rate of lithium in the electrolyte into lithium hexafluorophosphate was 97.5%, and the purity of the prepared lithium hexafluorophosphate was 99.2%.
Various embodiments of the application may exist in a range of forms; it should be understood that the description in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the application; it is therefore to be understood that the range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that a description of a range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1,2, 3, 4, 5, and 6, wherever applicable. In addition, whenever a numerical range is referred to herein, it is meant to include any reference number (fractional or integer) within the indicated range.
In the present application, unless otherwise specified, terms such as "upper" and "lower" are used specifically to refer to the orientation of the drawing in the figures. In addition, in the description of the present specification, the terms "include", "comprising" and the like mean "including but not limited to". Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. Relational terms such as "first" and "second", and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Herein, "and/or" describing an association relationship of an association object means that there may be three relationships, for example, a and/or B, may mean: a alone, a and B together, and B alone. For the association relation of three or more associated objects described by "and/or", it means that any one of the three associated objects may exist alone or any at least two of the three associated objects exist simultaneously, for example, for a, and/or B, and/or C, any one of A, B, C may exist alone or any two of the three associated objects exist simultaneously or three of the three associated objects exist simultaneously. Herein, "at least one" means one or more, and "a plurality" means two or more. "at least one", "at least one" or the like refer to any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.
The foregoing is only a specific embodiment of the application to enable those skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A method for preparing lithium hexafluorophosphate by a lithium-containing aluminum electrolyte, characterized in that the method for preparing lithium hexafluorophosphate by a lithium-containing aluminum electrolyte comprises the steps of:
Providing a mixed solution comprising phosphoric acid and an alcohol solvent;
Providing a lithium-containing cryolite-alumina molten salt electrolyte, mixing the cryolite-alumina molten salt electrolyte with the mixed solution, and reacting for a preset time at a first temperature to obtain slurry;
adding a neutralizing agent into the slurry to perform a neutralization reaction until the pH of the slurry reaches neutral;
Cooling the slurry to a second temperature, removing water in the slurry, filtering and collecting filtrate, removing solvent in the filtrate to obtain lithium hexafluorophosphate,
Wherein the neutralizer is at least one of sodium hydroxide and aluminum hydroxide, and the alcohol solvent is at least one of methanol and ethanol.
2. The method for producing lithium hexafluorophosphate by lithium-containing aluminum electrolyte according to claim 1, wherein the phosphoric acid is added in an amount of 1.2 to 2 times the theoretical amount that just causes the cryolite-alumina molten salt electrolyte to react completely.
3. The method for preparing lithium hexafluorophosphate by lithium-containing aluminum electrolyte according to claim 1, wherein the providing the mixed solution comprising phosphoric acid, alcohol solvent comprises: mixing concentrated phosphoric acid and an alcohol solvent to obtain a mixed solution, wherein the volume ratio of the alcohol solvent to the concentrated phosphoric acid is 3-20:1.
4. The method of preparing lithium hexafluorophosphate by lithium-containing aluminum electrolyte according to claim 1, wherein the first temperature is 60 to 200 ℃.
5. The method for preparing lithium hexafluorophosphate by lithium-containing aluminum electrolyte as claimed in claim 4, wherein the predetermined time is 1 to 24 hours.
6. The method for preparing lithium hexafluorophosphate by lithium-containing aluminum electrolyte according to claim 1, wherein the duration of the neutralization reaction is 30 to 90min.
7. The method of preparing lithium hexafluorophosphate by lithium-containing aluminum electrolyte according to claim 1, wherein the second temperature is 0 to 30 ℃.
8. The method for producing lithium hexafluorophosphate by means of a lithium-containing aluminum electrolyte according to claim 1, wherein the water in the slurry is removed by an adsorbent material.
9. The method for preparing lithium hexafluorophosphate by lithium-containing aluminum electrolyte according to claim 8, wherein the adsorbent material is at least one of molecular sieve, silica gel, and activated carbon.
10. The method for preparing lithium hexafluorophosphate by lithium-containing aluminum electrolyte as claimed in claim 1, wherein said removing the solvent in the filtrate comprises the steps of:
And (3) drying the filtrate at a low temperature of between 10 and 30 ℃.
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