阅读说明：本技术 一种小粒度中性氟化锂的制备方法 (Preparation method of small-particle-size neutral lithium fluoride ) 是由 李良彬 马木林 李玲玲 江证 章博文 陈刚 王超强 吴奇 邹栩 章小明 许鑫 于 2020-12-31 设计创作，主要内容包括：本发明公开了一种小粒度中性氟化锂的制备方法。所述小粒度中性氟化锂的制备方法包括以下步骤：(1)开启配料釜循环冷却水,向配料釜内加入纯水,开启引风机和搅拌,开启氟化氢气动控制阀门,使釜内溶液呈强酸性；(2)向所述步骤(1)得到的溶液中同时加入氟化氢和碳酸锂,釜内溶液为酸性,反应30min。本发明的小粒度中性氟化锂的制备方法,其优点在于控制碳酸锂及HF加料速度、反应过程中pH始终维持强酸性、反应温度低于35℃,最后用碳酸氢锂溶液调终点pH至5～6.5,再经表面活性剂处理,所得LiF不包裹碳酸锂,pH在5～7之间,主含量高,且晶体结构规则,产品质量进一步提升,满足现市场一些新材料对高品质氟化锂的要求。(The invention discloses a preparation method of small-particle-size neutral lithium fluoride. The preparation method of the small-particle-size neutral lithium fluoride comprises the following steps of: (1) starting a batching kettle to circulate cooling water, adding pure water into the batching kettle, starting a draught fan and stirring, and starting a hydrogen fluoride control valve to enable the solution in the kettle to be strongly acidic; (2) and (2) adding hydrogen fluoride and lithium carbonate into the solution obtained in the step (1) at the same time, reacting for 30min, wherein the solution in the kettle is acidic. The preparation method of the small-particle-size neutral lithium fluoride has the advantages that the feeding speed of lithium carbonate and HF is controlled, the pH value is always kept strong in the reaction process, the reaction temperature is lower than 35 ℃, finally, the end point pH value is adjusted to 5-6.5 by using a lithium bicarbonate solution, then, the lithium carbonate is treated by a surfactant, the obtained LiF does not wrap the lithium carbonate, the pH value is 5-7, the main content is high, the crystal structure is regular, the product quality is further improved, and the requirements of some new materials in the existing market on high-quality lithium fluoride are met.)

1. A preparation method of small-particle-size neutral lithium fluoride is characterized by comprising the following steps: the method comprises the following steps:

(1) starting a batching kettle to circulate cooling water, adding pure water into the batching kettle, starting a draught fan and stirring, and starting a hydrogen fluoride control valve to enable the solution in the kettle to be strongly acidic;

(2) simultaneously adding hydrogen fluoride and lithium carbonate into the solution obtained in the step (1), reacting for 30min, wherein the solution in the kettle is acidic;

(3) pumping the cooled lithium bicarbonate solution into the kettle, adjusting the end point pH to 5-6.5, and reacting for 30 min;

(4) centrifuging the materials in the kettle to obtain a lithium fluoride wet material, feeding the lithium fluoride wet material, pure water and a surfactant into a stirring and washing kettle, and stirring and washing for 30 min;

(5) pumping the materials in the kettle into a centrifugal machine for centrifugation to obtain a lithium fluoride wet material treated by a surfactant;

(6) drying the lithium fluoride wet material obtained in the step (5) to obtain dry LiF;

(7) and (4) screening the dried LiF obtained in the step (6), wherein the screened material is a finished product, and the screened material is put into the step (2) for recycling.

2. The method for preparing small-particle-size neutral lithium fluoride according to claim 1, wherein the method comprises the following steps: and (2) after hydrogen fluoride is added in the step (1), controlling the pH value to be less than 1 by using a strong acid solution.

3. The method for preparing small-particle-size neutral lithium fluoride according to claim 1, wherein the method comprises the following steps: in the step (2), the main content of lithium carbonate is more than or equal to 99.0%, and the adding speed of lithium carbonate is 2 kg/min-6 kg/min.

4. The method for preparing small-particle-size neutral lithium fluoride according to claim 1, wherein the method comprises the following steps: the adding speed of the hydrogen fluoride is 600L/h-1000L/h, the hydrogen fluoride is added once every 30kg of lithium carbonate is added, the pH value of the solution in the kettle is 1-1.5, and the temperature of the solution in the kettle is not more than 35 ℃.

5. The method for preparing small-particle-size neutral lithium fluoride according to claim 1, wherein the method comprises the following steps: in the step (3), the temperature of the cooled lithium bicarbonate solution is lower than 35 ℃, and the lithium content is 5-10 g/L.

6. The method for preparing small-particle-size neutral lithium fluoride according to claim 1, wherein the method comprises the following steps: in the step (4), the mass ratio of the lithium fluoride wet material to the pure water is 1: 5-1: 10, the surfactant is one or more of nonionic surfactants, and the addition amount of the surfactant is 0.1% -1.0% of the mass of the lithium fluoride wet material.

7. The method for preparing small-particle-size neutral lithium fluoride according to claim 1, wherein the method comprises the following steps: in the step (6), the drying temperature of the lithium fluoride wet material is 40-160 ℃, and the drying time is 12-24 h.

8. The method for preparing small-particle-size neutral lithium fluoride according to claim 1, wherein the method comprises the following steps: in the step (7), the aperture of the screen mesh is preferably 60-80 meshes.

Technical Field

The invention relates to a preparation method of small-particle-size neutral lithium fluoride.

Background

Lithium fluoride is an important lithium base material and has wide application in the industries of atomic energy industry, ceramics, optical fibers, electrolytic aluminum and the like. In recent years, with the rise of new energy sources such as lithium batteries, lithium fluoride is becoming more and more important as an important raw material for lithium hexafluorophosphate (LiPF6) as an electrolyte used in the production of lithium ion secondary batteries.

Lithium fluoride, the chemical formula of which is LiF, is an alkali metal halide, is a white crystal at room temperature, is slightly soluble in water, and has important effects, for example, in a ceramic material, the addition of high-quality LiF can reduce the sintering temperature of the ceramic product, shorten the sintering time, and improve the fluidity; the heat resistance, acid resistance, alkali resistance, wear resistance and cold and hot fatigue resistance of the ceramic are improved; the surface gloss of the ceramic is increased. Therefore, it is important to improve the LiF quality. The most common method for industrially producing lithium fluoride is to directly synthesize lithium fluoride by adding hydrofluoric acid into lithium carbonate, and lithium fluoride produced by the method is wrapped by lithium carbonate, so that the pH value is alkaline, the main content is low, the crystal structure is irregular, the product mobility is poor, and the quality requirement of a new material on lithium fluoride is difficult to meet.

Disclosure of Invention

Therefore, in order to solve the above problems, it is necessary to provide a method for preparing small-particle-size neutral lithium fluoride, so as to solve the technical problems that lithium fluoride prepared by the prior art is coated with lithium carbonate, so that the pH is alkaline, the main content is low, the crystal structure is irregular, and the product flowability is poor.

In order to achieve the purpose, the invention provides the following technical scheme:

a preparation method of small-particle size neutral lithium fluoride comprises the following steps:

(1) starting a batching kettle to circulate cooling water, adding pure water into the batching kettle, starting a draught fan and stirring, and starting a hydrogen fluoride control valve to enable the solution in the kettle to be strongly acidic;

(2) simultaneously adding hydrogen fluoride and lithium carbonate into the solution obtained in the step (1), reacting for 30min, wherein the solution in the kettle is acidic;

(3) pumping the cooled lithium bicarbonate solution into the kettle, adjusting the end point pH to 5-6.5, and reacting for 30 min;

(4) centrifuging the materials in the kettle to obtain a lithium fluoride wet material, feeding the lithium fluoride wet material, pure water and a surfactant into a stirring and washing kettle, and stirring and washing for 30 min;

(5) pumping the materials in the kettle into a centrifugal machine for centrifugation to obtain a lithium fluoride wet material treated by a surfactant;

(6) drying the lithium fluoride wet material obtained in the step (5) to obtain dry LiF;

(7) and (4) screening the dried LiF obtained in the step (6), wherein the screened material is a finished product, and the screened material is put into the step (2) for recycling.

Further, after hydrogen fluoride is added in the step (1), the pH of the strong acid solution is controlled to be less than 1.

Further, in the step (2), the main content of lithium carbonate added is more than or equal to 99.0%, and the adding speed of lithium carbonate is 2 kg/min-6 kg/min.

Further, the adding speed of the hydrogen fluoride is 600L/h-1000L/h, the hydrogen fluoride is added once every 30kg of lithium carbonate is added, the pH value of the solution in the kettle is 1-1.5, and the temperature of the solution in the kettle is not more than 35 ℃.

Further, in the step (3), the temperature of the cooled lithium bicarbonate solution is lower than 35 ℃, and the lithium content is 5-10 g/L.

Further, in the step (4), the mass ratio of the lithium fluoride wet material to the pure water is 1: 5-1: 10, the surfactant is one or more of nonionic surfactants, and the addition amount of the surfactant is 0.1% -1.0% of the mass of the lithium fluoride wet material.

Further, in the step (6), the drying temperature of the lithium fluoride wet material is 40-160 ℃, and the drying time is 12-24 h.

Furthermore, in the step (7), the aperture of the screen mesh is preferably 60-80 meshes.

The invention relates to a preparation method of small-particle-size neutral lithium fluoride, which comprises the following steps of: adding hydrogen fluoride into a certain volume of pure water to prepare a strong acid solution, slowly adding lithium carbonate while adding acid, and always maintaining the solution to be acidic; adjusting the end point pH to 5-6.5 by a lithium bicarbonate solution, and controlling the reaction temperature not to exceed 35 ℃ in the whole feeding process; centrifuging the lithium fluoride slurry, and stirring and washing the wet material, pure water and a surfactant once according to a certain mass ratio; and finally, centrifuging, drying and sieving to obtain the final product.

Compared with the prior art, the preparation method of the small-granularity neutral lithium fluoride has the advantages that the lithium carbonate and HF feeding speed is controlled, the pH value is always kept strong in the reaction process, the reaction temperature is lower than 35 ℃, finally, the end point pH value is adjusted to 5-6.5 by using a lithium bicarbonate solution, the lithium carbonate is treated by a surfactant, the obtained LiF does not wrap the lithium carbonate, the pH value is 5-7, the main content is high, the crystal structure is regular, the product quality is further improved, and the requirements of some new materials in the existing market on high-quality lithium fluoride are met.

Drawings

Fig. 1 is a process flow chart of a method for preparing small-particle-size neutral lithium fluoride according to an embodiment of the present invention.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1, the present invention provides a method for preparing small-particle-size neutral lithium fluoride, comprising the following steps:

(1) starting a batching kettle to circulate cooling water, adding pure water into the batching kettle, starting a draught fan and stirring, and starting a hydrogen fluoride control valve to enable the solution in the kettle to be strongly acidic;

(2) simultaneously adding hydrogen fluoride and lithium carbonate into the solution obtained in the step (1), reacting for 30min, wherein the solution in the kettle is acidic;

(3) pumping the cooled lithium bicarbonate solution into the kettle, adjusting the end point pH to 5-6.5, and reacting for 30 min;

(4) centrifuging the materials in the kettle to obtain a lithium fluoride wet material, feeding the lithium fluoride wet material, pure water and a surfactant into a stirring and washing kettle, and stirring and washing for 30 min;

(5) pumping the materials in the kettle into a centrifugal machine for centrifugation to obtain a lithium fluoride wet material treated by a surfactant;

(6) drying the lithium fluoride wet material obtained in the step (5) to obtain dry LiF;

(7) and (4) screening the dried LiF obtained in the step (6), wherein the screened material is a finished product, and the screened material is put into the step (2) for recycling.

Further, after hydrogen fluoride is added in the step (1), the pH of the strong acid solution is controlled to be less than 1.

Further, in the step (2), the main content of lithium carbonate added is more than or equal to 99.0%, and the adding speed of lithium carbonate is 2 kg/min-6 kg/min.

Further, the adding speed of the hydrogen fluoride is 600L/h-1000L/h, the hydrogen fluoride is added once every 30kg of lithium carbonate is added, the pH value of the solution in the kettle is 1-1.5, and the temperature of the solution in the kettle is not more than 35 ℃.

Further, in the step (3), the temperature of the cooled lithium bicarbonate solution is lower than 35 ℃, and the lithium content is 5-10 g/L.

Further, in the step (4), the mass ratio of the lithium fluoride wet material to the pure water is 1: 5-1: 10, the surfactant is one or more of nonionic surfactants, and the addition amount of the surfactant is 0.1% -1.0% of the mass of the lithium fluoride wet material.

Further, in the step (6), the drying temperature of the lithium fluoride wet material is 40-160 ℃, and the drying time is 12-24 h.

Furthermore, in the step (7), the aperture of the screen mesh is preferably 60-80 meshes.

The invention relates to a preparation method of small-particle-size neutral lithium fluoride, which comprises the following steps of: adding hydrogen fluoride into a certain volume of pure water to prepare a strong acid solution, slowly adding lithium carbonate while adding acid, and always maintaining the solution to be acidic; adjusting the end point pH to 5-6.5 by a lithium bicarbonate solution, and controlling the reaction temperature not to exceed 35 ℃ in the whole feeding process; centrifuging the lithium fluoride slurry, and stirring and washing the wet material, pure water and a surfactant once according to a certain mass ratio; and finally, centrifuging, drying and sieving to obtain the final product.

Compared with the prior art, the preparation method of the small-granularity neutral lithium fluoride has the advantages that the lithium carbonate and HF feeding speed is controlled, the pH value is always kept strong in the reaction process, the reaction temperature is lower than 35 ℃, finally, the end point pH value is adjusted to 5-6.5 by using a lithium bicarbonate solution, the lithium carbonate is treated by a surfactant, the obtained LiF does not wrap the lithium carbonate, the pH value is 5-7, the main content is high, the crystal structure is regular, the product quality is further improved, and the requirements of some new materials in the existing market on high-quality lithium fluoride are met.

Example 1

And (3) starting the circulating cooling water of the batching kettle, adding pure water with the diameter of about 2m into the batching kettle, starting the draught fan and stirring, and starting the hydrogen fluoride control valve to ensure that the pH value of the solution in the kettle is less than 1. Slowly adding battery-grade lithium carbonate at the speed of 2kg/min, and supplementing HF once at the speed of 800L/h when the pH monitor in the kettle shows that the pH is 1.5, so that the pH in the kettle is maintained at 1-1.5. The steps are repeated until the addition of 350kg of battery-grade lithium carbonate is finished, and the reaction is continued for 30 min. Pumping LiHCO3 solution with Li content of 7.6g/L into the kettle, adjusting the end point pH to 6.0, and continuing the reaction for 30 min. The reaction temperature is controlled not to exceed 35 ℃ in the whole feeding process. Pumping the LiF slurry in the batching kettle into a centrifuge for centrifugation to obtain 349kg of LiF wet material. And then, feeding the LiF wet material and pure water into a stirring and washing kettle according to the mass ratio of 1:7, adding 2.1kg of polyvinylpyrrolidone, and stirring and washing for 30 min. And (3) further centrifuging the slurry, and drying the wet material in a double-cone dryer at the drying temperature of 100 ℃ for 12 h. The dried material is separated by a 60-mesh screen to obtain 293kg of finished product under the screen and 2.4kg of material on the screen.

Example 2

And (3) starting the circulating cooling water of the batching kettle, adding pure water with the diameter of about 2m into the batching kettle, starting the draught fan and stirring, and starting the hydrogen fluoride control valve to ensure that the pH value of the solution in the kettle is less than 1. Slowly adding battery-grade lithium carbonate at the speed of 5kg/min, and supplementing HF once at the speed of 600L/h when the pH monitor in the kettle shows that the pH is 1.5, so that the pH in the kettle is maintained at 1-1.5. The steps are repeated until the addition of 400kg of battery-grade lithium carbonate is finished, and the reaction is continued for 30 min. Pumping LiHCO3 solution with Li content of 8.5g/L into the kettle, adjusting the end point pH to 6.5, and continuing the reaction for 30 min. The reaction temperature is controlled not to exceed 35 ℃ in the whole feeding process. Pumping the LiF slurry in the batching kettle into a centrifuge for centrifugation to obtain 380kgLiF wet material. And then, feeding the LiF wet material and pure water into a stirring and washing kettle according to the mass ratio of 1:5, adding 1.5kg of polyvinylpyrrolidone, and stirring and washing for 30 min. And (3) further centrifuging the slurry, and drying the wet material in a double-cone dryer at the drying temperature of 120 ℃ for 8 h. The dried material is separated by a 80-mesh screen to obtain 327kg of finished product under the screen and 3.3kg of material on the screen.

Example 3

And (3) starting the circulating cooling water of the batching kettle, adding pure water with the diameter of about 2m into the batching kettle, starting the draught fan and stirring, and starting the hydrogen fluoride control valve to ensure that the pH value of the solution in the kettle is less than 1. Slowly adding battery-grade lithium carbonate at the speed of 4kg/min, and supplementing HF once at the speed of 900L/h when the pH monitor in the kettle shows that the pH is 1.5, so that the pH in the kettle is maintained at 1-1.5. The above steps are repeated until the addition of 450kg of battery-grade lithium carbonate is finished, and the reaction is continued for 30 min. Pumping LiHCO3 solution with Li content of 8.7g/L into the kettle, adjusting the end point pH to 5.5, and continuing the reaction for 30 min. The reaction temperature is controlled not to exceed 35 ℃ in the whole feeding process. Pumping the LiF slurry in the batching kettle into a centrifuge for centrifugation to obtain 405kgLiF wet material. And then feeding the LiF wet material and pure water into a stirring and washing kettle according to the mass ratio of 1:8, adding 2.2kg of polyvinylpyrrolidone, and stirring and washing for 30 min. And (3) further centrifuging the slurry, and drying the wet material in a double-cone dryer at the drying temperature of 140 ℃ for 8 h. The dried material is separated by a 80-mesh screen to obtain 356kg of finished product under the screen and 3.2kg of material on the screen.

Example 4

And (3) starting the circulating cooling water of the batching kettle, adding pure water with the diameter of about 2m into the batching kettle, starting the draught fan and stirring, and starting the hydrogen fluoride control valve to ensure that the pH value of the solution in the kettle is less than 1. Slowly adding battery-grade lithium carbonate at the speed of 6kg/min, and supplementing HF once at the speed of 500L/h when the pH monitor in the kettle shows that the pH is 1.5, so that the pH in the kettle is maintained at 1-1.5. The steps are repeated until the 500kg of battery-grade lithium carbonate is added, and the reaction is continued for 30 min. Pumping LiHCO3 solution with Li content of 9.6g/L into the kettle, adjusting the end point pH to 5.0, and continuing the reaction for 30 min. The reaction temperature is controlled not to exceed 35 ℃ in the whole feeding process. Pumping the LiF slurry in the batching kettle into a centrifuge for centrifugation to obtain 444kgLiF wet material. And then, feeding the LiF wet material and pure water into a stirring and washing kettle according to the mass ratio of 1:10, adding 3.6kg of polyvinylpyrrolidone, and stirring and washing for 30 min. And (3) further centrifuging the slurry, and drying the wet material in a double-cone dryer at the drying temperature of 100 ℃ for 20 h. The dried material was screened through a 80 mesh screen to obtain 392kg of finished product under the screen and 3.8kg of material on the screen.

The results of the analysis of each lithium fluoride product in the above examples are shown in the following table.

TABLE 1 analysis of results for each cell grade lithium carbonate product in the examples

The above description is only for the purpose of illustrating specific embodiments of the present invention, and should not be construed as limiting the scope of the present invention, and all equivalent changes and modifications made in accordance with the spirit of the present invention should be considered as falling within the scope of the present invention.