Preparation method of high-purity lithium fluoride

Abstract

The invention provides a preparation method of high-purity lithium fluoride. Comprising the following steps: roasting a mixture of lepidolite concentrate and sulfate to obtain clinker; the clinker is ground, the ground clinker is heated and leached in a water leaching mode, and leachate is obtained; removing impurities from the leachate, and filtering to obtain a purified solution; extracting lithium from the purified liquid, and separating to obtain a lithium-containing organic phase; adding pure water into the lithium-containing organic phase, and introducing carbon dioxide for reverse extraction until a lithium bicarbonate solution with the pH value of 7-9 is obtained; removing impurities from the lithium bicarbonate solution through resin, and adding hydrofluoric acid into the lithium bicarbonate solution subjected to impurity removal to obtain lithium fluoride slurry; solid lithium fluoride in the lithium fluoride slurry is separated, and the solid lithium fluoride is washed, filtered and dried to obtain the high-purity lithium fluoride. According to the method, liquid-liquid reaction is adopted in the lithium fluoride preparation process, the reaction is easy to control, sufficient reaction is facilitated, the preparation process is simple, and the preparation process is safe.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion battery materials, and in particular to a method for preparing high-purity lithium fluoride. Background Art

[0002] Lithium fluoride is an important lithium-based basic material. High-purity lithium fluoride is usually required as the raw material for manufacturing lithium hexafluorophosphate (LiPF6), the electrolyte used in lithium-ion batteries. The conventional method of preparing high-purity lithium fluoride from lithium mica has problems such as difficult to control the reaction process and low reaction efficiency. Summary of the invention

[0003] The present application provides a method for preparing high-purity lithium fluoride which is easy to control the reaction process and is conducive to improving the reaction efficiency.

[0004] In a first aspect, an embodiment of the present application provides a method for preparing high-purity lithium fluoride, the method for preparing high-purity lithium fluoride comprising:

[0005] roasting the mixture of lepidolite concentrate and sulfate to obtain clinker;

[0006] Grinding the clinker, and heating and leaching the ground clinker by water immersion to obtain a leachate;

[0007] removing impurities and filtering the leaching solution to obtain a purified solution;

[0008] Extracting lithium from the purified liquid to separate and obtain a lithium-containing organic phase;

[0009] Adding pure water to the lithium-containing organic phase and introducing carbon dioxide for stripping until a lithium bicarbonate solution with a pH of 7 to 9 is obtained;

[0010] Passing the lithium bicarbonate solution through a resin to remove impurities, and adding hydrofluoric acid to the lithium bicarbonate solution after the impurities are removed to obtain a lithium fluoride slurry;

[0011] The solid lithium fluoride in the lithium fluoride slurry is separated, and the solid lithium fluoride is washed, filtered and dried to obtain high-purity lithium fluoride.

[0012] According to the first aspect, in a possible implementation, in the step of roasting the mixture of lepidolite concentrate and sulfate to obtain clinker, the sulfate includes one or more of sodium sulfate, potassium sulfate, calcium sulfate, and ferrous sulfate.

[0013] According to the first aspect, in a possible implementation, in the step of roasting the mixture of lepidolite concentrate and sulfate to obtain clinker, the roasting temperature is 650° C. to 1100° C., and the roasting time is 0.2 h to 6 h.

[0014] According to the first aspect, in a possible implementation, in the step of grinding the clinker and heating the ground clinker by water immersion to obtain the leaching solution, the leaching temperature is 40° C. to 80° C., and the leaching time is 0.1 h to 5 h.

[0015] According to the first aspect, in a possible implementation, the step of removing impurities and filtering the leachate to obtain a purified solution includes:

[0016] Adding an impurity remover to the leachate, wherein the impurity remover comprises one or more of activated carbon, sodium carbonate, potassium carbonate, and sodium hydroxide;

[0017] The purified liquid was obtained by filtration and separation.

[0018] According to the first aspect, in a possible implementation manner, the step of filtering and separating includes:

[0019] After the leachate reacts with the impurity remover for a preset time, it is filtered through a plate and frame filter press to obtain a primary filtrate;

[0020] The primary filtrate is finely filtered through a filter membrane with a pore size of 0.1 μm to 0.5 μm to obtain a purified liquid.

[0021] According to the first aspect, in a possible implementation, the step of extracting lithium from the purified liquid and separating to obtain a lithium-containing organic phase comprises:

[0022] The purified liquid is subjected to 2 to 6 levels of countercurrent extraction to separate and obtain a lithium-containing organic phase.

[0023] According to the first aspect, in a possible implementation, in the step of subjecting the purified liquid to 2 to 6 stages of countercurrent extraction to separate the lithium-containing organic phase, the extractant includes one or more of benzoyl acetone, benzoyl trifluoroacetone, furanyl trifluoroacetone, and bromobenzoyl trifluoroacetone; the co-extractant includes tributyl phosphate, and the diluent includes sulfonated kerosene.

[0024] According to the first aspect, in a possible implementation, in the step of adding pure water to the lithium-containing organic phase and introducing carbon dioxide for stripping until a lithium bicarbonate solution with a pH of 7 to 9 is obtained, the reaction temperature is controlled to be less than or equal to 40°C.

[0025] According to the first aspect, in a possible implementation, in the step of removing impurities from the lithium bicarbonate solution through a resin and adding hydrofluoric acid to the lithium bicarbonate solution after impurities removal to obtain a lithium fluoride slurry, the mass fraction of the hydrofluoric acid is greater than or equal to 30%, and the pH at the reaction endpoint is controlled at 1 to 3.

[0026] The method for preparing high-purity lithium fluoride provided in the present application is a liquid-liquid reaction in the process of preparing lithium fluoride, which can fully react, is easy to control, has a simple preparation process, and is safe; the prepared lithium fluoride has a high purity and can meet the preparation requirements of battery-grade electrolyte lithium salts. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 It is a schematic flow chart of a method for preparing high-purity lithium fluoride in one embodiment of the present application;

[0029] Figure 2 is a process flow chart of a method for preparing high-purity lithium fluoride in an embodiment of the present application;

[0030] Figure 3 It is a schematic flow chart of a method for preparing high-purity lithium fluoride in another embodiment of the present application. DETAILED DESCRIPTION

[0031] The words "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that may provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0032] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of the present invention.

[0034] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0035] like Figure 1 and Figure 2 As shown, the embodiment of the present application provides a method for preparing high-purity lithium fluoride, and the method for preparing high-purity lithium fluoride comprises the following steps:

[0036] Step S10, roasting the mixture of lepidolite concentrate and sulfate to obtain clinker;

[0037] Step S20, grinding the clinker, and heating and leaching the ground clinker by water immersion to obtain a leachate;

[0038] Step S30, removing impurities and filtering the leachate to obtain a purified liquid;

[0039] Step S40, extracting lithium from the purified liquid to separate and obtain a lithium-containing organic phase;

[0040] Step S50, adding pure water to the lithium-containing organic phase and introducing carbon dioxide for stripping until a lithium bicarbonate solution with a pH of 7 to 9 is obtained;

[0041] Step S60, passing the lithium bicarbonate solution through a resin to remove impurities, and adding hydrofluoric acid to the lithium bicarbonate solution after impurities removal to obtain lithium fluoride slurry;

[0042] Step S70, separating the solid lithium fluoride in the lithium fluoride slurry, and washing, filtering, and drying the solid lithium fluoride to obtain high-purity lithium fluoride.

[0043] In this embodiment, by mixing and roasting lithium mica concentrate with sulfate, a clinker that is easy to leach is formed. The lithium element in the clinker mainly exists in the form of lithium sulfate, which provides convenience for subsequent leaching operations. After grinding the clinker, heating and leaching by water immersion can more effectively extract the lithium element from the clinker into the leachate, thereby improving the recovery rate of lithium. The leachate is subjected to impurity removal and filtration operations, and solid impurities and soluble impurities therein can be effectively removed to obtain a purified liquid. Through the extraction and lithium extraction step, the purity of lithium is further improved by utilizing the selective adsorption of lithium by the extractant, and the lithium-containing organic phase is separated. In the stripping step, by adding pure water and introducing carbon dioxide into the lithium-containing organic phase, the reaction conditions can be accurately controlled, so that lithium is stripped out in the form of lithium bicarbonate, and impurities in the organic phase are further removed. The reaction of lithium bicarbonate solution and hydrofluoric acid is a liquid-liquid reaction with clear reaction conditions and reaction end point. By accurately controlling parameters such as the amount of reactants added, reaction time and temperature, accurate control of the reaction process can be achieved. The entire preparation process does not involve extreme conditions such as high temperature and high pressure, avoiding potential safety risks.

[0044] The high-purity lithium fluoride prepared by the above steps has high purity and can meet the preparation requirements of battery-grade electrolyte lithium salt.

[0045] Based on the above embodiment, the steps of the method for preparing high-purity lithium fluoride are described in detail below.

[0046] In step S10, the sulfate includes one or more of sodium sulfate, potassium sulfate, calcium sulfate, and ferrous sulfate. These sulfates can react chemically with the lithium element and other components in the lithium mica concentrate during the roasting process to generate soluble compounds such as lithium sulfate (Li2SO4), thereby facilitating subsequent water leaching extraction.

[0047] In actual operation, the appropriate type and ratio of sulfate can be selected according to the composition of the lithium mica concentrate and the required lithium extraction efficiency. By adjusting the type and ratio of sulfate, the conditions of the roasting reaction can be optimized, the conversion efficiency of lithium elements can be improved, and the impurity content in subsequent processing steps can be reduced.

[0048] The roasting temperature and roasting time are two key factors affecting the conversion efficiency of lithium. In the optional embodiment, the roasting temperature is 650°C to 1100°C. This temperature range not only ensures the full reaction between lithium and sulfate, but also avoids the side reactions and increased energy consumption caused by too high a temperature. The roasting time is 0.2h to 6h. The appropriate roasting time can ensure the effective conversion of lithium while avoiding energy waste and equipment wear caused by too long a time.

[0049] In step S20, the clinker obtained by roasting in step S10 is ground and heated and leached at a specific temperature and time by water immersion, thereby obtaining a leachate containing lithium. The ball mill can effectively refine the clinker through the collision and friction between the steel balls or other abrasives inside and the clinker. Adding water as a grinding medium makes it easier for the clinker to flow and disperse in the ball mill, which can accelerate the refinement process of the clinker and improve the grinding efficiency.

[0050] The clinker can be ground with water in a ball mill to refine the clinker and increase its specific surface area, thereby facilitating the subsequent water extraction step.

[0051] The leaching temperature can be set between 40°C and 80°C. Within this temperature range, the chemical reaction rate is moderate, which can ensure that lithium is effectively transferred from the clinker to the leaching solution, while preventing undesirable side reactions from occurring due to excessively high temperatures.

[0052] The leaching time is 0.1h to 5h. Within this time range, lithium can be fully leached from the clinker to achieve a higher leaching efficiency.

[0053] like Figure 3 As shown, step S30 includes: step S31, adding an impurity remover to the leachate, wherein the impurity remover includes one or more of activated carbon, sodium carbonate, potassium carbonate, and sodium hydroxide;

[0054] By adding specific impurity removers, divalent and trivalent metal ions in the leachate, such as Ca 2 +, Mg2+, Fe2+, Cu2+, Fe3+, etc., to improve the purity of subsequent lithium fluoride products.

[0055] The impurity removers selected include one or more of activated carbon, sodium carbonate, potassium carbonate, and sodium hydroxide. These impurity removers react or combine with metal ions to generate water-insoluble precipitates, thereby facilitating separation of the precipitates from the leachate.

[0056] Activated carbon mainly removes organic matter and some metal ions through adsorption. Sodium carbonate and potassium carbonate react with metal ions to form carbonate precipitates. Sodium hydroxide can not only be used to adjust the pH value of the solution, but also react with certain metal ions to form hydroxide precipitates.

[0057] Activated carbon: mainly removes organic matter and some metal ions through adsorption.

[0058] Sodium carbonate and potassium carbonate: react with metal ions to form carbonate precipitates.

[0059] Sodium hydroxide: It can not only be used to adjust the pH value of the solution, but also react with certain metal ions to form hydroxide precipitates.

[0060] Step S32, filtering and separating to obtain a purified liquid.

[0061] The precipitate generated by the reaction of the leachate and the impurity remover and the unreacted impurity remover are separated by filtration to obtain a purified liquid.

[0062] In step S32, multi-stage filtration can be performed. For example, after the leachate reacts with the impurity remover for a preset time, it is first filtered through a plate and frame filter press. The plate and frame filter press uses the extrusion effect of the filter cloth and the filter plate to effectively separate the solid particles from the liquid to obtain the primary filtrate. During the filtration process, the appropriate pressure should be controlled to avoid damage to the filter cloth or too tight filter cake, which may cause filtration difficulties. The primary filtrate is then finely filtered through a filter membrane with a pore size of 0.1μm to 0.5μm. The precision filtration membrane has extremely high filtration accuracy and can effectively remove impurities such as tiny particles, colloids and bacteria remaining in the primary filtrate. During the filtration process, the status of the filter membrane should be checked regularly to ensure the filtration effect.

[0063] Step S40 comprises: the purified liquid is subjected to 2 to 6 levels of countercurrent extraction to separate and obtain a lithium-containing organic phase.

[0064] By utilizing the different solubility characteristics of different substances in two immiscible solvents, the purpose of separation and purification is achieved through repeated contact and separation. In countercurrent extraction, the extractant and the purification liquid containing the target substance flow countercurrently in the extraction column. Through multiple contacts and separations, the target substance is gradually extracted into the extractant.

[0065] In this embodiment, the extractant includes one or more of benzoyl acetone, benzoyl trifluoroacetone, furanyl trifluoroacetone, and bromobenzoyl trifluoroacetone; the synergist includes tributyl phosphate, and the diluent includes sulfonated kerosene. The synergist, such as tributyl phosphate, can enhance the extraction ability of the extractant for lithium and improve the extraction efficiency. The diluent, such as sulfonated kerosene, can be used to adjust the concentration and viscosity of the extractant to make it more suitable for extraction operation.

[0066] In step S50, the reaction temperature is controlled to be less than or equal to 40° C. When the reaction is controlled to be carried out under low temperature conditions, lithium bicarbonate can be stably generated and not easily decomposed, which is beneficial to improving the purity and yield of the final product.

[0067] CO2 is introduced into the solution containing lithium carbonate, which combines with lithium ions in the lithium-containing organic phase to form lithium bicarbonate, which is stripped by pure water. The aqueous solution of lithium bicarbonate is acidic, and the progress of the stripping reaction can be accurately judged by monitoring the pH value of the solution. When the pH value of the solution reaches 7-9, it means that the stripping reaction is almost complete, and the stripping process can be stopped at this time.

[0068] In step S60, the mass fraction of the hydrofluoric acid is greater than or equal to 30%, and the mass fraction of the hydrofluoric acid is crucial to the fluorination process. Only when the mass fraction of the hydrofluoric acid is high enough can the fluorination reaction be fully carried out. High concentration of hydrofluoric acid also helps to improve the purity and yield of the product.

[0069] The pH at the end of the reaction is controlled between 1 and 3 to ensure that the fluorination reaction is fully carried out. This pH range also helps to reduce the occurrence of side reactions, thereby improving the purity and yield of the product.

[0070] In a first embodiment:

[0071] The lithium mica concentrate, sodium sulfate, calcium sulfate and ferrous sulfate are mixed in a ratio of 70:20:5:5, and the mixed materials are put into a rotary kiln for roasting at a temperature of 850°C and a roasting time of 2 hours;

[0072] The roasted clinker enters the ball mill and is ground with water. The ratio of water to material is 1.5:1 and the grinding is carried out for 1 hour.

[0073] The ball-milled material was leached at a temperature of 60°C for 1 h to obtain a leachate;

[0074] The obtained leaching solution is impurity-removed, activated carbon and sodium carbonate are added, stirred for 2 hours, passed through a plate and frame, and then passed through a precision filter to obtain a purified solution;

[0075] The purified liquid is extracted, and an extraction system is configured with benzoyl acetone, tributyl phosphate and sulfonated kerosene for three-stage countercurrent extraction to obtain a lithium-containing organic phase and an aqueous phase, and then pure water is added to the organic phase, and carbon dioxide is introduced for stripping. The temperature is controlled to be lower than 40° C. during stripping, and when the pH of the stripping solution is 7 to 8, the carbon dioxide is stopped to obtain a lithium bicarbonate solution;

[0076] The obtained lithium bicarbonate solution is passed through resin to remove impurities, and hydrofluoric acid is added to the solution after impurities removal, and is slowly added dropwise until the pH value is 1 to 3, and then reacted for 1 hour, filtered, stirred, washed, filtered again, and dried to obtain a white lithium fluoride solid powder.

[0077] In the second embodiment:

[0078] The lithium mica concentrate, sodium sulfate and ferrous sulfate are mixed in a ratio of 70:25:5, and the mixed materials are put into a rotary kiln for roasting at a temperature of 850°C and a roasting time of 2 hours;

[0079] The roasted clinker enters the ball mill and is ground with water. The ratio of water to material is 2:1 and the grinding is continued for 1 hour.

[0080] The ball-milled material was leached at a temperature of 80°C for 1 hour to obtain a leachate;

[0081] The obtained leaching solution is impurity-removed, activated carbon and sodium carbonate are added, stirred for 1 hour, passed through a plate and frame, and then passed through a precision filter to obtain a purified solution;

[0082] The purified liquid is extracted, and an extraction system is configured with benzoyltrifluoroacetone, furanyltrifluoroacetone, tributyl phosphate and sulfonated kerosene to perform three-stage countercurrent extraction to obtain a lithium-containing organic phase and an aqueous phase, and then pure water is added to the organic phase, and carbon dioxide is introduced for stripping. The temperature is controlled to be lower than 40° C. during stripping, and when the pH of the stripping solution is 7 to 8, the carbon dioxide is stopped to obtain a lithium bicarbonate solution;

[0083] The obtained lithium bicarbonate solution is passed through resin to remove impurities, and hydrofluoric acid is added to the solution after impurities removal, and is slowly added dropwise until the pH value is 1 to 3, and then reacted for 1 hour, filtered, stirred, washed, filtered again, and dried to obtain a white lithium fluoride solid powder.

[0084] In the third embodiment:

[0085] The lithium mica concentrate, sodium sulfate, potassium sulfate and ferrous sulfate are mixed in a ratio of 70:20:5:5, and the mixed materials are put into a rotary kiln for roasting at a temperature of 900°C and a roasting time of 1 hour;

[0086] The roasted clinker enters the ball mill and is ground with water. The ratio of water to material is 1:1.2 and the grinding is carried out for 1 hour.

[0087] The ball-milled material was leached at a temperature of 60°C for 1 h to obtain a leachate;

[0088] The obtained leaching solution is impurity-removed, sodium hydroxide, activated carbon and sodium carbonate are added, stirred for 1 hour, passed through a plate and frame, and then passed through a precision filter to obtain a purified solution;

[0089] The purified liquid is extracted, and an extraction system is configured with benzoyl acetone, tributyl phosphate and sulfonated kerosene for three-stage countercurrent extraction to obtain a lithium-containing organic phase and an aqueous phase, and then pure water is added to the organic phase, and carbon dioxide is introduced for stripping. The temperature is controlled to be lower than 40° C. during stripping, and when the pH of the stripping solution is 7 to 8, the carbon dioxide is stopped to obtain a lithium bicarbonate solution;

[0090] The obtained lithium bicarbonate solution is passed through resin to remove impurities, and hydrofluoric acid is added to the solution after impurities removal, and is slowly added dropwise until the pH value is 1 to 3, and then reacted for 1 hour, filtered, stirred and washed, filtered again, and dried to obtain a white lithium fluoride solid powder.

[0091] As shown in the following table, the content of lithium fluoride in the high-purity lithium fluoride prepared in the present application is greater than 99.98%, which meets the battery-grade lithium fluoride standard.

[0092] Table 1: Sample lithium fluoride test data

[0093]

[0094]

[0095] The applicant declares that the present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the method of the present invention, addition of auxiliary steps, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing high-purity lithium fluoride, characterized in that: The preparation method of the high-purity lithium fluoride comprises: roasting the mixture of lepidolite concentrate and sulfate to obtain clinker; Grinding the clinker, and heating and leaching the ground clinker by water immersion to obtain a leachate; removing impurities and filtering the leaching solution to obtain a purified solution; Extracting lithium from the purified liquid to separate and obtain a lithium-containing organic phase; Adding pure water to the lithium-containing organic phase and introducing carbon dioxide for stripping until a lithium bicarbonate solution with a pH of 7 to 9 is obtained; Passing the lithium bicarbonate solution through a resin to remove impurities, and adding hydrofluoric acid to the lithium bicarbonate solution after the impurities are removed to obtain a lithium fluoride slurry; The solid lithium fluoride in the lithium fluoride slurry is separated, and the solid lithium fluoride is washed, filtered and dried to obtain high-purity lithium fluoride.

2. The method for preparing high-purity lithium fluoride according to claim 1, characterized in that: In the step of roasting the mixture of lithium mica concentrate and sulfate to obtain clinker, the sulfate includes one or more of sodium sulfate, potassium sulfate, calcium sulfate and ferrous sulfate.

3. The method for preparing high-purity lithium fluoride according to claim 2, characterized in that: In the step of roasting the mixture of lithium mica concentrate and sulfate to obtain clinker, the roasting temperature is 650° C. to 1100° C., and the roasting time is 0.2 h to 6 h.

4. The method for preparing high-purity lithium fluoride according to claim 1, characterized in that: In the step of grinding the clinker and heating the ground clinker by water immersion to obtain the leaching solution, the leaching temperature is 40° C. to 80° C. and the leaching time is 0.1 h to 5 h.

5. The method for preparing high-purity lithium fluoride according to claim 1, characterized in that: The step of removing impurities and filtering the leachate to obtain a purified solution comprises: Adding an impurity remover to the leachate, wherein the impurity remover comprises one or more of activated carbon, sodium carbonate, potassium carbonate, and sodium hydroxide; The purified liquid was obtained by filtration and separation.

6. The method for preparing high-purity lithium fluoride according to claim 5, characterized in that: The step of filtering and separating comprises: After the leachate reacts with the impurity remover for a preset time, it is filtered through a plate and frame filter press to obtain a primary filtrate; The primary filtrate is finely filtered through a filter membrane with a pore size of 0.1 μm to 0.5 μm to obtain a purified liquid.

7. The method for preparing high-purity lithium fluoride according to claim 1, characterized in that: The step of extracting lithium from the purified liquid and separating to obtain a lithium-containing organic phase comprises: The purified liquid is subjected to 2 to 6 levels of countercurrent extraction to separate and obtain a lithium-containing organic phase.

8. The method for preparing high-purity lithium fluoride according to claim 1, characterized in that: In the step of subjecting the purified liquid to 2 to 6 levels of countercurrent extraction to separate and obtain a lithium-containing organic phase, the extractant includes one or more of benzoyl acetone, benzoyl trifluoroacetone, furoyl trifluoroacetone, and bromobenzoyl trifluoroacetone; the co-extractant includes tributyl phosphate, and the diluent includes sulfonated kerosene.

9. The method for preparing high-purity lithium fluoride according to claim 2, characterized in that: In the step of adding pure water to the lithium-containing organic phase and introducing carbon dioxide for stripping until a lithium bicarbonate solution with a pH of 7 to 9 is obtained, the reaction temperature is controlled to be less than or equal to 40°C.

10. The method for preparing high-purity lithium fluoride according to claim 3, characterized in that: In the step of removing impurities from the lithium bicarbonate solution through a resin and adding hydrofluoric acid to the lithium bicarbonate solution after impurities removal to obtain a lithium fluoride slurry, the mass fraction of the hydrofluoric acid is greater than or equal to 30%, and the pH at the reaction endpoint is controlled to be between 1 and 3.

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