A method for preparing large particle size lithium fluoride
Patent Information
- Application Number
- CN202611367973.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-04
- Publication Date
- 2026-10-30
AI Technical Summary
[0006]为了解决现有技术存在的不足，本发明的目的在于提供一种大粒径氟化锂的制备方法，本发明通过优化碳酸氢锂碳化液与氢氟酸的反应方式及工艺条件，实现了大粒径氟化锂的可控制备，所得产品具有粒径较大、纯度较高的特点；本发明工艺流程简单，操作条件温和，能够有效改善现有氟化锂制备过程中粒径较小、分布不均等问题，具有良好的应用价值
（1）本发明通过将碳酸氢锂碳化液滴加至氢氟酸溶液中，使反应物的加入方式由传统的酸滴碱方式转变为碳酸氢锂碳化液滴加至氢氟酸溶液中的反向滴加方式，并通过将滴加过程设置为第一阶段和第二阶段，在第一阶段滴加结束后间歇，再进行第二阶段滴加，且控制第一阶段滴加速度低于第二阶段滴加速度，从而调节氟化反应过程中的反应速率，有利于氟化锂晶体的生长，获得具有较大粒径的氟化锂产品。
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Figure CN123002879A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of inorganic salt chemical synthesis technology, specifically to a method for preparing large-particle-size lithium fluoride. Background Technology
[0002] Lithium fluoride (LiF) is an important inorganic fluoride material, widely used in molten salt electrolysis, infrared optical materials, enamel industry, and the preparation of electrolyte salts for lithium-ion batteries due to its excellent chemical and thermal stability. With the development of related applications, higher requirements are being placed on the purity, particle size characteristics, and processing performance of lithium fluoride products.
[0003] Currently, the main methods for preparing lithium fluoride include the reaction between lithium-containing compounds and fluorine-containing compounds. Among these, the reaction of lithium-containing solutions with hydrofluoric acid is a commonly used method. In actual production, the formation of lithium fluoride crystals is affected by various factors such as reaction conditions, material mixing methods, and post-processing techniques, resulting in variations in the particle size characteristics and particle state of the obtained products.
[0004] Existing lithium fluoride preparation processes typically result in lithium fluoride products with small particle size and uneven particle size distribution, which affects the product's performance during subsequent processing, transportation, and application. Furthermore, some preparation processes require precise control of reaction conditions, and there is still room for improvement in process stability and product consistency.
[0005] Therefore, developing a stable, easy-to-operate method for preparing lithium fluoride products with large particle size and excellent performance is of great significance for improving the quality of lithium fluoride products and expanding their application range. Summary of the Invention
[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing large-particle-size lithium fluoride. By optimizing the reaction mode and process conditions of lithium bicarbonate carbide solution and hydrofluoric acid, the present invention achieves controllable preparation of large-particle-size lithium fluoride, resulting in a product with large particle size and high purity. The process of the present invention is simple and the operating conditions are mild, which can effectively improve the problems of small particle size and uneven distribution in the existing lithium fluoride preparation process, and has good application value.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing large-particle-size lithium fluoride includes the following steps: (1) Preparation of lithium bicarbonate carbonized liquid.
[0008] Lithium carbonate is mixed with water, and carbon dioxide gas is introduced to carry out a carbonization reaction until the solution becomes clear, thus obtaining a lithium bicarbonate carbonized solution.
[0009] In this invention, the mass ratio of lithium carbonate to water is 1:15~60.
[0010] (2) Perform fluorination reaction.
[0011] The lithium bicarbonate carbonized liquid obtained in step (1) is added dropwise to the hydrofluoric acid solution to carry out the fluorination reaction.
[0012] The dripping process is divided into a first stage and a second stage; after the first stage of dripping is completed, an intermittent treatment is performed before the second stage of dripping is performed; and the dripping rate of the first stage is lower than that of the second stage.
[0013] In this invention, the concentration of lithium bicarbonate in the lithium bicarbonate carbonization solution is 2wt%~6wt%, and the concentration of hydrofluoric acid solution is 3wt%~8wt%.
[0014] Furthermore, the dropping rate in the first stage is 5~10 mL / min, and the dropping time is 0.5~2 h.
[0015] Furthermore, the dropping rate in the second stage is 10-15 mL / min, and the dropping time is 0.5-2 h.
[0016] Furthermore, the ratio of the dripping rate of the first stage to the second stage is 1:1.5 to 1:3; after the first stage of dripping is completed, there is an interval of 0.3 to 1 hour before the second stage of dripping is carried out.
[0017] In this invention, the fluorination reaction is carried out at room temperature throughout, with a stirring speed of 50-100 r / min; after the lithium bicarbonate carbonization liquid is added dropwise, the reaction continues for 1-2 hours.
[0018] (3) Post-processing yields large-particle-size lithium fluoride.
[0019] After the fluorination reaction is completed, the pH of the system is adjusted using lithium bicarbonate carbonization solution to obtain a reaction slurry; then the reaction slurry is aged, washed and dried to obtain large-particle-size lithium fluoride.
[0020] The pH of the system was adjusted to 5.0-6.0.
[0021] Furthermore, the aging temperature is 20~40℃, and the aging time is 2~6h.
[0022] Furthermore, the drying temperature is 80~120℃, and the drying time is 4~8h.
[0023] The present invention also provides a large-particle-size lithium fluoride prepared by the above preparation method, wherein the purity of the lithium fluoride is above 99.9 wt%, and the proportion of particles with a particle size >100 μm is above 60% in terms of volume distribution.
[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention changes the reaction rate in the fluorination process by adding lithium bicarbonate carbonization liquid to hydrofluoric acid solution in a reverse dropping manner, which is achieved by adding the reaction liquid to hydrofluoric acid solution in a dropwise manner, instead of the traditional acid-to-base method. The dropping process is divided into a first stage and a second stage. After the first stage of dropping is completed, the second stage of dropping is carried out after an interval. The dropping rate in the first stage is controlled to be lower than that in the second stage, thereby adjusting the reaction rate in the fluorination process, which is beneficial to the growth of lithium fluoride crystals and obtaining lithium fluoride products with larger particle size.
[0025] (2) By controlling the concentrations of lithium bicarbonate carbide solution and hydrofluoric acid solution and combining them with a staged dropwise addition method, this invention can reduce the influence of reactant concentration on the crystal formation process, improve the growth process of lithium fluoride crystals, and result in lithium fluoride with a larger particle size. In particular, the lithium fluoride prepared by the method of this invention has a particle size >100 μm accounting for more than 60% by volume distribution.
[0026] (3) In this invention, the pH of the reaction system is adjusted to 5.0-6.0 by using lithium bicarbonate carbonization liquid after the fluorination reaction is completed, and further combined with aging, washing and drying treatment, so that the reaction product can obtain better crystal morphology and product performance, and the purity of the prepared lithium fluoride reaches more than 99.9 wt%.
[0027] (4) The preparation method provided by the present invention has a simple process flow. By controlling the addition method of lithium bicarbonate carbide liquid and hydrofluoric acid solution, the dropping process and the post-reaction treatment conditions, the preparation of large-particle-size lithium fluoride can be achieved without introducing complex equipment or additional crystal control steps, and it has good process applicability. Attached Figure Description
[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some schematic diagrams of certain embodiments of the present invention, and therefore should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0029] Figure 1 This is a microscopic morphology image of the lithium fluoride prepared in Example 1 of the present invention. Detailed Implementation
[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Of course, the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.
[0031] Unless otherwise specified, all chemical reagents and materials in this invention are purchased from the market or synthesized from raw materials purchased from the market.
[0032] The present invention will be further described below through specific embodiments.
[0033] Example 1 A method for preparing large-particle-size lithium fluoride includes the following steps: (1) Preparation of lithium bicarbonate carbonized liquid Weigh 40.5g of lithium carbonate, add it to 1300mL of deionized water, stir and mix, and pass carbon dioxide gas through to carry out the carbonization reaction until the solution is clear, to obtain lithium bicarbonate carbonized solution.
[0034] The lithium bicarbonate concentration in the obtained lithium bicarbonate carbonized solution was found to be 3.59 wt%.
[0035] (2) Fluorination reaction Add 500 mL of 4.9 wt% hydrofluoric acid solution to the reaction vessel, turn on the stirrer, and control the stirring speed at 80 r / min.
[0036] The lithium bicarbonate carbonized solution prepared above was added dropwise to a hydrofluoric acid solution to carry out a fluorination reaction. The dropwise addition process was divided into two stages: In the first stage, the solution was added dropwise at a rate of 8 mL / min for 1 hour; then the addition was stopped and paused for 0.5 hours.
[0037] In the second stage, the addition was continued at a rate of 13 mL / min for 1 hour.
[0038] The above fluorination reaction was carried out entirely at 25°C.
[0039] After the lithium bicarbonate carbonized liquid was added dropwise, the reaction continued for 1.5 hours.
[0040] (3) Post-processing After the fluorination reaction is completed, lithium bicarbonate carbonization solution is added to adjust the pH of the reaction system to 5.5, thus obtaining the reaction slurry.
[0041] The resulting reaction slurry was aged at 25°C for 4 hours, filtered, and the filter cake was washed three times with deionized water. It was then dried at 100°C for 6 hours to obtain a large-particle-size lithium fluoride product.
[0042] Example 2 A method for preparing large-particle-size lithium fluoride includes the following steps: (1) Preparation of lithium bicarbonate carbonized liquid Weigh 50.0g of lithium carbonate, add it to 1600mL of deionized water, stir and mix, and pass carbon dioxide gas through to carry out the carbonization reaction until the solution is clear, to obtain lithium bicarbonate carbonized solution.
[0043] The lithium bicarbonate concentration in the obtained lithium bicarbonate carbonized solution was found to be 4.5 wt%.
[0044] (2) Fluorination reaction Add 550 mL of 5.5 wt% hydrofluoric acid solution to the reaction vessel, turn on the stirrer, and control the stirring speed at 80 r / min.
[0045] The lithium bicarbonate carbonized liquid obtained above was added dropwise to a hydrofluoric acid solution to carry out a fluorination reaction.
[0046] In the first stage, the solution was added dropwise at a rate of 7 mL / min for 1 hour; then the addition was stopped and paused for 0.5 hours.
[0047] In the second stage, the addition was continued at a dropping rate of 14 mL / min for 0.7 h.
[0048] The above fluorination reaction was carried out entirely at 25°C.
[0049] After the lithium bicarbonate carbonized liquid was added dropwise, the reaction continued for 1.5 hours.
[0050] (3) Post-processing After the fluorination reaction is completed, lithium bicarbonate carbonization solution is added to adjust the pH of the reaction system to 5.8, and the reaction slurry is obtained.
[0051] The resulting reaction slurry was aged at 30°C for 6 hours, filtered, and the filter cake was washed three times with deionized water. It was then dried at 100°C for 6 hours to obtain a large-particle-size lithium fluoride product.
[0052] Example 3 A method for preparing large-particle-size lithium fluoride includes the following steps: (1) Preparation of lithium bicarbonate carbonized liquid Weigh 42.0g of lithium carbonate, add it to 1600mL of deionized water, stir and mix, and pass carbon dioxide gas through to carry out the carbonization reaction until the solution is clear, to obtain lithium bicarbonate carbonized solution.
[0053] The lithium bicarbonate solution was tested and found to have a lithium bicarbonate concentration of 3.0 wt%.
[0054] (2) Fluorination reaction Add 600 mL of 4.0 wt% hydrofluoric acid solution to the reaction vessel, turn on the stirrer, and control the stirring speed at 60 r / min.
[0055] The lithium bicarbonate carbonized liquid obtained above was added dropwise to a hydrofluoric acid solution to carry out a fluorination reaction.
[0056] In the first stage, the solution was added dropwise at a rate of 6 mL / min for 1.5 h; then the addition was stopped and paused for 0.5 h.
[0057] In the second stage, the addition was continued at a dropping rate of 12 mL / min for 1.2 h.
[0058] The above fluorination reaction was carried out entirely at 25°C.
[0059] After the lithium bicarbonate carbonized liquid was added dropwise, the reaction continued for 2 hours.
[0060] (3) Post-processing After the fluorination reaction is completed, lithium bicarbonate carbonization solution is added to adjust the pH of the reaction system to 5.2, thus obtaining the reaction slurry.
[0061] The resulting reaction slurry was aged at 25°C for 3 hours, filtered, and the filter cake was washed three times with deionized water. It was then dried at 100°C for 6 hours to obtain a large-particle-size lithium fluoride product.
[0062] Example 4 A method for preparing large-particle-size lithium fluoride includes the following steps: (1) Preparation of lithium bicarbonate carbonized liquid Weigh 40.5g of lithium carbonate, add it to 2600mL of deionized water, stir and mix, and pass carbon dioxide gas through to carry out the carbonization reaction until the solution is clear, to obtain lithium bicarbonate carbonized solution.
[0063] The lithium bicarbonate concentration in the obtained lithium bicarbonate carbonized solution was found to be 1.8 wt%.
[0064] (2) Fluorination reaction Add 1000 mL of 2.45 wt% hydrofluoric acid solution to the reaction vessel, turn on the stirrer, and control the stirring speed at 80 r / min.
[0065] The lithium bicarbonate carbonized liquid obtained above was added dropwise to a hydrofluoric acid solution to carry out a fluorination reaction.
[0066] In the first stage, the solution was added dropwise at a rate of 12 mL / min for 1 hour; then the addition was stopped and paused for 0.5 hours.
[0067] In the second stage, the addition was continued at a rate of 24 mL / min for 1 hour.
[0068] The above fluorination reaction was carried out entirely at 25°C.
[0069] After the lithium bicarbonate carbonized liquid was added dropwise, the reaction continued for 1.5 hours.
[0070] (3) Post-processing After the fluorination reaction is completed, lithium bicarbonate carbonization solution is added to adjust the pH of the reaction system to 5.5, thus obtaining the reaction slurry.
[0071] The resulting reaction slurry was aged at 25°C for 4 hours, filtered, and the filter cake was washed three times with deionized water. It was then dried at 100°C for 6 hours to obtain a large-particle-size lithium fluoride product.
[0072] Example 5 A method for preparing large-particle-size lithium fluoride includes the following steps: (1) Preparation of lithium bicarbonate carbonized liquid Weigh 40.5g of lithium carbonate, add it to 1300mL of deionized water, stir and mix, and pass carbon dioxide gas through to carry out the carbonization reaction until the solution becomes clear, thus obtaining lithium bicarbonate carbonized solution.
[0073] The lithium bicarbonate concentration in the obtained lithium bicarbonate carbonized solution was found to be 3.59 wt%.
[0074] (2) Fluorination reaction Add 500 mL of 4.9 wt% hydrofluoric acid solution to the reaction vessel, turn on the stirrer, and control the stirring speed at 80 r / min.
[0075] The lithium bicarbonate carbonized liquid obtained above was added dropwise to a hydrofluoric acid solution to carry out a fluorination reaction.
[0076] In the first stage, the solution was added dropwise at a rate of 6 mL / min for 1 hour; then the addition was stopped and paused for 0.5 hours.
[0077] In the second stage, the addition was continued at a rate of 18 mL / min for 1 hour.
[0078] The above fluorination reaction was carried out entirely at 25°C.
[0079] After the lithium bicarbonate carbonized liquid was added dropwise, the reaction continued for 1.5 hours.
[0080] (3) Post-processing After the fluorination reaction is completed, lithium bicarbonate carbonization solution is added to adjust the pH of the reaction system to 6.0, and the reaction slurry is obtained.
[0081] The resulting reaction slurry was aged at 25°C for 4 hours, filtered, and the filter cake was washed three times with deionized water. It was then dried at 100°C for 6 hours to obtain a large-particle-size lithium fluoride product.
[0082] Comparative Example 1 This comparative example provides a method for preparing lithium fluoride, which differs from Example 1 in that: the fluorination reaction is carried out by the traditional acid-to-base method, that is, hydrofluoric acid solution is added dropwise to lithium bicarbonate carbonization solution, instead of adding lithium bicarbonate carbonization solution dropwise to hydrofluoric acid solution.
[0083] The specific steps are as follows: (1) Preparation of lithium bicarbonate carbonized liquid Weigh 40.5g of lithium carbonate, add it to 1300mL of deionized water, stir and mix, and pass carbon dioxide gas through to carry out the carbonization reaction until the solution becomes clear, thus obtaining lithium bicarbonate carbonized solution.
[0084] The lithium bicarbonate concentration in the obtained lithium bicarbonate carbonized solution was found to be 3.59 wt%.
[0085] (2) Fluorination reaction Place the above-mentioned lithium bicarbonate carbonized liquid into a reaction vessel, turn on the stirrer, and control the stirring speed at 80 r / min.
[0086] Take 500 mL of a 4.9 wt% hydrofluoric acid solution and add it dropwise to the above lithium bicarbonate carbonization solution to carry out the fluorination reaction.
[0087] The hydrofluoric acid solution was added dropwise at a rate of 21 mL / min for 2 hours, and the system temperature was maintained at 25°C during the addition process.
[0088] After the hydrofluoric acid solution was added dropwise, the reaction continued for 1.5 hours.
[0089] (3) Post-processing After the reaction is complete, lithium bicarbonate carbonization solution is added to adjust the pH of the reaction system to 5.5, thus obtaining the reaction slurry.
[0090] The resulting reaction slurry was aged at 25°C for 4 hours, filtered, and the filter cake was washed three times with deionized water. It was then dried at 100°C for 6 hours to obtain the lithium fluoride product.
[0091] Comparative Example 2 This comparative example provides a method for preparing lithium fluoride, which differs from Example 1 in that it uses a high-concentration reaction system.
[0092] The specific steps are as follows: (1) Preparation of lithium bicarbonate carbonized liquid Weigh 40.5g of lithium carbonate, add it to about 390mL of deionized water, stir and mix, and pass carbon dioxide gas through to carry out the carbonization reaction until the solution is clear, to obtain a high-concentration lithium bicarbonate carbonized solution.
[0093] The lithium bicarbonate solution was tested and found to have a lithium bicarbonate concentration of 12 wt%.
[0094] (2) Fluorination reaction Add 160 mL of 15 wt% hydrofluoric acid solution to the reaction vessel, turn on the stirrer, and control the stirring speed at 80 r / min.
[0095] The above-mentioned lithium bicarbonate carbonized solution was added dropwise to a hydrofluoric acid solution to carry out a fluorination reaction.
[0096] In the first stage, the solution was added dropwise at a rate of 8 mL / min for 1 hour; then the addition was stopped and paused for 0.5 hours.
[0097] In the second stage, the addition was continued at a rate of 13 mL / min for 1 hour.
[0098] The above fluorination reaction was carried out entirely at 25°C.
[0099] After the lithium bicarbonate carbonized liquid was added dropwise, the reaction continued for 1.5 hours.
[0100] (3) Post-processing After the fluorination reaction is completed, lithium bicarbonate carbonization solution is added to adjust the pH of the reaction system to 5.5, thus obtaining the reaction slurry.
[0101] The resulting reaction slurry was aged at 25°C for 4 hours, filtered, and the filter cake was washed three times with deionized water. It was then dried at 100°C for 6 hours to obtain the lithium fluoride product.
[0102] Comparative Example 3 This comparative example provides a method for preparing lithium fluoride, which differs from Example 1 in that the lithium bicarbonate carbonization solution is not added in stages, but is added in one go at a constant rate.
[0103] The specific steps are as follows: (1) Preparation of lithium bicarbonate carbonized liquid Weigh 40.5g of lithium carbonate, add it to 1300mL of deionized water, stir and mix, and pass carbon dioxide gas through to carry out the carbonization reaction until the solution becomes clear, thus obtaining lithium bicarbonate carbonized solution.
[0104] The lithium bicarbonate concentration in the obtained lithium bicarbonate carbonized solution was found to be 3.59 wt%.
[0105] (2) Fluorination reaction Add 500 mL of 4.9 wt% hydrofluoric acid solution to the reaction vessel, turn on the stirrer, and control the stirring speed at 80 r / min.
[0106] The above-mentioned lithium bicarbonate carbonized solution was added dropwise to the hydrofluoric acid solution at a constant rate of 10.5 mL / min over a period of 2 hours.
[0107] The above fluorination reaction was carried out entirely at 25°C.
[0108] After the lithium bicarbonate carbonized liquid was added dropwise, the reaction continued for 1.5 hours.
[0109] (3) Post-processing After the fluorination reaction is completed, lithium bicarbonate carbonization solution is added to adjust the pH of the reaction system to 5.5, thus obtaining the reaction slurry.
[0110] The resulting reaction slurry was aged at 25°C for 4 hours, filtered, and the filter cake was washed three times with deionized water. It was then dried at 100°C for 6 hours to obtain the lithium fluoride product.
[0111] Comparative Example 4 This comparative example provides a method for preparing lithium fluoride, which differs from Example 1 in that the pH of the system is adjusted to 7.0 after the fluorination reaction is completed.
[0112] The specific steps are as follows: (1) Preparation of lithium bicarbonate carbonized liquid Weigh 40.5g of lithium carbonate, add it to 1300mL of deionized water, stir and mix, and pass carbon dioxide gas through to carry out the carbonization reaction until the solution becomes clear, thus obtaining lithium bicarbonate carbonized solution.
[0113] The lithium bicarbonate concentration in the obtained lithium bicarbonate carbonized solution was found to be 3.59 wt%.
[0114] (2) Fluorination reaction Add 500 mL of 4.9 wt% hydrofluoric acid solution to the reaction vessel, turn on the stirrer, and control the stirring speed at 80 r / min.
[0115] The above-mentioned lithium bicarbonate carbonized solution was added dropwise to the hydrofluoric acid solution.
[0116] In the first stage, the solution was added dropwise at a rate of 8 mL / min for 1 hour; then the addition was stopped and paused for 0.5 hours.
[0117] In the second stage, the addition was continued at a rate of 13 mL / min for 1 hour.
[0118] The above fluorination reaction was carried out entirely at 25°C.
[0119] After the lithium bicarbonate carbonized liquid was added dropwise, the reaction continued for 1.5 hours.
[0120] (3) Post-processing After the fluorination reaction is completed, lithium bicarbonate carbonization solution is added to adjust the pH of the reaction system to 7.0, and the reaction slurry is obtained.
[0121] The resulting reaction slurry was aged at 25°C for 4 hours, filtered, and the filter cake was washed three times with deionized water. It was then dried at 100°C for 6 hours to obtain the lithium fluoride product.
[0122] Comparative Example 5 This comparative example provides a method for preparing lithium fluoride, which differs from Example 1 in that the stirring speed during the fluorination reaction is increased.
[0123] The specific steps are as follows: (1) Preparation of lithium bicarbonate carbonized liquid Weigh 40.5g of lithium carbonate, add it to 1300mL of deionized water, stir and mix, and pass carbon dioxide gas through to carry out the carbonization reaction until the solution becomes clear, thus obtaining lithium bicarbonate carbonized solution.
[0124] The lithium bicarbonate concentration in the obtained lithium bicarbonate carbonized solution was found to be 3.59 wt%.
[0125] (2) Fluorination reaction Add 500 mL of 4.9 wt% hydrofluoric acid solution to the reaction vessel, turn on the stirrer, and control the stirring speed at 300 r / min.
[0126] The above-mentioned lithium bicarbonate carbonized solution was added dropwise to the hydrofluoric acid solution.
[0127] In the first stage, the solution was added dropwise at a rate of 8 mL / min for 1 hour; then the addition was stopped and paused for 0.5 hours.
[0128] In the second stage, the addition was continued at a rate of 13 mL / min for 1 hour.
[0129] The above fluorination reaction was carried out entirely at 25°C.
[0130] After the lithium bicarbonate carbonized liquid was added dropwise, the reaction continued for 1.5 hours.
[0131] (3) Post-processing After the fluorination reaction is completed, lithium bicarbonate carbonization solution is added to adjust the pH of the reaction system to 5.5, thus obtaining the reaction slurry.
[0132] The resulting reaction slurry was aged at 25°C for 4 hours, filtered, and the filter cake was washed three times with deionized water. It was then dried at 100°C for 6 hours to obtain the lithium fluoride product.
[0133] I. Product Performance Testing 1. Particle size distribution test The particle size distribution of the obtained lithium fluoride products was determined using a laser particle size analyzer. The test indicators included: D10; D50; D90; and the percentage of particles with a diameter >100 μm. The particle size distribution was statistically analyzed using volume distribution.
[0134] 2. Purity Test The content of metal impurities in lithium fluoride products was detected by inductively coupled plasma optical emission spectrometry (ICP-OES), and the purity of lithium fluoride was calculated based on the detection results.
[0135] II. Test Results Table 1 Performance Test Results The lithium fluoride products prepared in Examples 1-5 all exhibited large particle sizes. Specifically, the lithium fluoride obtained in Example 1 had a D50 of 125 μm, with particles >100 μm accounting for 68% of the total. Examples 3 and 4 further increased the proportion of particles >100 μm, reaching 72% and 76% respectively, demonstrating that the present invention can promote the growth of lithium fluoride crystals towards larger particle sizes by adjusting the reaction conditions.
[0136] Comparative Example 1 uses the traditional acid-to-base reaction method, and the resulting product has a D50 of only 28 μm, and the proportion of particles with a diameter >100 μm is 0, which is significantly lower than that of Example 1. This indicates that the reverse drop method of adding lithium bicarbonate carbonization liquid to hydrofluoric acid solution is beneficial to obtaining lithium fluoride with a larger particle size.
[0137] Comparative Example 2 used a high-concentration reaction system, and the resulting product had a D50 reduced to 22 μm, with the proportion of particles >100 μm being 0. This indicates that reducing the concentration of the reaction system can improve the crystal growth process and avoid the formation of a large number of fine particles.
[0138] Comparative Example 3 did not use the first and second stage dropwise addition method. The resulting product had a D50 of 38 μm, and the proportion of particles with a diameter >100 μm was only 6%. This shows that staged dropwise addition and control of the dropwise addition rate at different stages can help improve the size of lithium fluoride particles.
[0139] In Comparative Example 4, the pH of the reaction endpoint was adjusted to 7.0, and the resulting product had a D50 of 32 μm. The proportion of particles with a diameter >100 μm was reduced to 3%, indicating that controlling the pH of the reaction system within a suitable range can improve the growth of lithium fluoride crystals.
[0140] Comparative Example 5 used a higher stirring speed of 300 r / min, and the resulting product had a D50 of 45 μm and a particle size >100 μm ratio of 10%, which was lower than that of Example 1. This indicates that a lower stirring speed is beneficial for obtaining large-particle-size lithium fluoride products.
[0141] In summary, this invention achieves effective control over the particle size of lithium fluoride crystals by reverse-dropping lithium bicarbonate solution into hydrofluoric acid solution, combined with two-stage dropwise addition, appropriate reaction concentration, pH control, and post-treatment processes. The lithium fluoride prepared using this method exhibits larger particle size and higher purity, meeting the requirements for preparing large-particle-size lithium fluoride products.
[0142] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A method for preparing large-particle-size lithium fluoride, characterized in that, Includes the following steps: (1) Mix lithium carbonate with water and pass carbon dioxide gas through to carry out carbonation reaction until the solution is clear to obtain lithium bicarbonate carbonation solution; (2) The lithium bicarbonate carbonized liquid is added dropwise to the hydrofluoric acid solution, and the dropwise addition is divided into a first stage and a second stage to carry out the fluorination reaction; (3) After the fluorination reaction is completed, the pH of the system is adjusted by lithium bicarbonate carbonization liquid to obtain a reaction slurry. The reaction slurry is aged, washed and dried to obtain the large-particle-size lithium fluoride.
2. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of lithium carbonate to water is 1:15~60.
3. The preparation method according to claim 1, characterized in that, In step (2), the concentration of lithium bicarbonate in the lithium bicarbonate carbonization solution is 2wt%~6wt%, and the concentration of hydrofluoric acid solution is 3wt%~8wt%.
4. The preparation method according to claim 1, characterized in that, In step (2), the dropping rate in the first stage is 5~10 mL / min, and the dropping time is 0.5~2 h.
5. The preparation method according to claim 1, characterized in that, In step (2), the dropping rate in the second stage is 10~15 mL / min, and the dropping time is 0.5~2 h.
6. The preparation method according to claim 1, characterized in that, In step (2), the ratio of the dripping speed of the first stage to that of the second stage is 1:1.5 to 1:
3. After the first stage of dripping is completed, the second stage of dripping is carried out after an interval of 0.3 to 1 hour.
7. The preparation method according to claim 1, characterized in that, Step (2) is carried out at room temperature with a stirring speed of 50~100r / min; after the lithium bicarbonate carbonized liquid is added, the reaction continues for 1~2h.
8. The preparation method according to claim 1, characterized in that, In step (3), the pH of the system is adjusted to 5.0~6.
0.
9. The preparation method according to claim 1, characterized in that, In step (3), the aging temperature is 20~40℃ and the aging time is 2~6h; the drying temperature is 80~120℃ and the drying time is 4~8h.
10. A large-particle-size lithium fluoride prepared by the preparation method according to any one of claims 1 to 9, characterized in that, The lithium fluoride has a purity of 99.9 wt% or higher, and the proportion of particles with a diameter >100 μm is 60% or higher by volume distribution.