Preparation method of large-particle sodium fluoride
Through the acid-base convection synthesis process, the problem of difficult to obtain large-particle sodium fluoride and severe corrosion equipment in the traditional method is solved, and high-efficiency and low-cost preparation of large-particle sodium fluoride is achieved, with a particle size of 30 mesh and a high purity.
Patent Information
- Application Number
- CN202411745154.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-02
- Publication Date
- 2025-03-11
AI Technical Summary
Traditional methods are easy to produce powdered sodium fluoride with smaller particle size, making it difficult to obtain large-particle sodium fluoride. At the same time, the neutralization reaction seriously corrodes the reactor, which has high requirements for the equipment material and high production costs.
The acid-base convection synthesis method is adopted to reasonably regulate the inlet flow, and the direct contact between acid and alkali when feeding the material, the pH of the synthetic liquid is monitored in real time, the raw material inlet volume is accurately calculated, the neutralization reaction is cancelled, and the convection synthesis process is adopted.
The requirements for equipment are significantly reduced, the generation rate of large-particle sodium fluoride is improved, and the particle size is as high as 30 mesh, which reduces production costs and improves production efficiency, and obtains high-purity large-particle sodium fluoride.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of preparation of large-particle sodium fluoride, and in particular to a preparation method of large-particle sodium fluoride. Background Art
[0002] Sodium fluoride (NaF) is an inorganic compound composed of sodium ions and fluoride ions, in the form of a white crystalline powder. It is easily soluble in water, slightly soluble in ethanol, and insoluble in organic solvents such as ether. The melting point of sodium fluoride is 993°C and the boiling point is 1700°C. It is easy to absorb moisture in the air and can react with acids to generate corresponding fluorides and hydrogen. At high temperatures, sodium fluoride can react with metal oxides such as silicon and aluminum to generate corresponding fluorides. With the continuous expansion of the application of sodium fluoride in metallurgy, ceramics, glass, medicine, pesticides and other fields, the demand for large-particle sodium fluoride is also gradually increasing. Large-particle sodium fluoride has better performance and effects in certain specific applications, such as as a flux, emulsifier, preservative, etc.
[0003] Neutralizing hydrofluoric acid with sodium hydroxide is a mature method for producing sodium fluoride. This method adds 40% hydrofluoric acid to a reactor, then slowly adds soda ash or caustic soda, fully stirs until the reaction solution is neutral, and obtains the product through crystallization, centrifugal dehydration, and drying. This method is easy to generate powdered sodium fluoride with a smaller particle size, but it is difficult to obtain large-particle sodium fluoride. At the same time, the neutralization reaction seriously corrodes the reactor, and the requirements for equipment materials are very high, and the production cost is relatively high. Therefore, it is particularly important to design a preparation method for large-particle sodium fluoride to solve the above technical problems. Summary of the invention
[0004] The invention provides a method for preparing sodium fluoride with large particles in order to solve the problems that the traditional method is easy to generate powdered sodium fluoride with small particle size, it is difficult to obtain sodium fluoride with large particles, the reaction seriously corrodes the reactor, the material requirements for the equipment are very high, and the production cost is high.
[0005] In order to achieve the above object, the present invention adopts the following technical scheme: a method for preparing large-particle sodium fluoride, comprising the following steps: a. adding 1000 kg of high-purity water to a reactor and stirring at 18-20 r / min; b. by reasonably regulating the liquid inlet flow rate, the hydrofluoric acid metering tank is 200-400 m 3 / h, sodium hydroxide metering tank is 800-1600m 3 / h, control the synthesis ratio, c. Add 1100kg of hydrofluoric acid with a content of 50% and 5200kg of sodium hydroxide with a content of 30% into the reactor in a convection manner, d. After the synthesis is completed, measure the pH of the synthetic liquid with pH test paper, and add appropriate amount of sodium hydroxide or hydrofluoric acid according to the actual situation to adjust the pH of the synthetic liquid to 7, e. Maintain the temperature at 70℃, stir at 18-20r / min for 1h, and obtain large-particle sodium fluoride through centrifugation, drying and screening processes.
[0006] Preferably, in step b, the liquid level and weighing readings of the acid and alkali metering tanks are monitored throughout the liquid inlet process to avoid liquid bubbling.
[0007] Preferably, in the step c, the temperature is kept at 70° C. throughout the synthesis, and the pH value is controlled at 6-7.
[0008] Compared with the prior art, the advantages and positive effects of the present invention are: 1. The present invention adopts the synthesis method of acid-base convection, reasonably adjusts the flow rate, makes the acid and alkali contact directly when feeding, monitors the pH of the synthetic liquid in real time, accurately calculates the amount of raw material liquid inlet, and does not need to undergo neutralization reaction in the reactor, which not only reduces the equipment cost, but also increases the generation rate of large-particle sodium fluoride, with a particle size of up to 30 mesh. Compared with the traditional preparation method, this process significantly reduces the requirements for equipment, and has high synthesis purity, which solves the problem that the traditional method is easy to generate powdered sodium fluoride with a smaller particle size, it is difficult to obtain large-particle sodium fluoride, and the neutralization reaction seriously corrodes the reactor, and has very high requirements on the equipment material and high production cost. 2. The present invention eliminates the original alkali solution temporary storage tank, filter press and mother liquor filtration storage facilities, and significantly improves production efficiency; an electromagnetic flowmeter is used to accurately control the liquid inlet flow rate to 200-400m for hydrofluoric acid. 3 / h, sodium hydroxide 800-1600m 3 / h to ensure the stability of the liquid inlet; change the liquid inlet synthesis method to convection to ensure that the product particle size meets the requirements. DETAILED DESCRIPTION
[0009] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described below in conjunction with the attached table and embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.
[0010] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure.
[0011] Example 1 Add 1000kg of high-purity water to the reactor and stir at 20r / min; adjust the flow rate of hydrofluoric acid metering liquid to 300m 3 / h, the sodium hydroxide metering liquid flow rate is 1200m 3 / h; 1100kg of hydrofluoric acid with a content of 50% and 5200kg of sodium hydroxide with a content of 30% are put into the reactor by convection, and the synthesis process is controlled to be constant at 70℃ and pH 7; after the synthesis is completed, the pH of the synthetic liquid is measured to be 7; the temperature is kept at 70℃ and stirred at 20r / min for 1h. The synthesized sodium fluoride is placed in a centrifuge, centrifuged at 25Hz for 12min, and then dried at a constant temperature of 110℃ for 1h with a drying drum, and finally sieved with a vibrating screen to obtain a large-particle sodium fluoride product. The yield of large-particle sodium fluoride obtained by the above preparation method reaches 95%, and the particle size is 30-40 mesh.
[0012] The preparation method in this embodiment adopts the synthesis method of acid-base convection, so that the acid and base are in direct contact when feeding, without the need for neutralization reaction in the reactor, reasonable adjustment of flow rate, real-time monitoring of the pH of the synthetic liquid, and accurate calculation of the amount of raw material liquid input, which not only reduces the equipment cost, but also increases the generation rate of large-particle sodium fluoride, and its particle size is as high as 30 meshes. Compared with the traditional preparation method, the acid-base convection synthesis process significantly reduces the requirements for equipment and has high synthesis purity.
[0013] Example 2 The method is basically the same as Example 1, except that the feed synthesis method adopts the alkali neutralization method, the yield of large-particle sodium fluoride is 65%, and the particle size is 80-120 mesh.
[0014] Example 3 The method is basically the same as Example 1, except that the synthesis endpoint pH is controlled to be 8, the final yield of large-particle sodium fluoride is 75%, and the particle size is 120-150 mesh.
[0015] Example 4 The method is basically the same as Example 1, except that the synthesis stirring speed is adjusted to 15 r / min, and the final yield of large-particle sodium fluoride is 82%, and the particle size is 80-100 mesh.
[0016] Example 5 The method is basically the same as Example 1, except that the synthesis stirring time is adjusted to 2 h, the final yield of large-particle sodium fluoride is 88%, and the particle size is 40-80 mesh.
[0017] The final yield and particle size of the above examples are as follows: In summary, the preparation method eliminates the need for the original alkali solution temporary storage tank, filter press and mother liquor filtration storage facilities, and significantly improves production efficiency; the electromagnetic flowmeter is used to accurately control the liquid inlet flow rate to 200-400m 3 / h, sodium hydroxide 800-1600m 3 / h, to ensure the stability of the liquid feed; change the liquid feed synthesis method to convection, centrifuge, dry, and screen, the 30-40 mesh product yield reaches 95%. Compared with the traditional preparation method, the acid-base convection synthesis process reduces the high requirements for the reactor and related production facilities, and obtains high-yield large-particle sodium fluoride based on the existing facilities.
Claims
1. A method for preparing large-particle sodium fluoride, comprising the following steps, characterized in that: a. Add 1000kg of high-purity water to the reactor and stir at 18-20r / min. b. By reasonably adjusting the inlet flow rate, the hydrofluoric acid metering tank is 200-400m 3 / h, sodium hydroxide metering tank is 800-1600m 3 / h, control the synthesis ratio, c. Add 1100kg of hydrofluoric acid with a content of 50% and 5200kg of sodium hydroxide with a content of 30% into the reactor in a convection manner, d. After the synthesis is completed, measure the pH of the synthetic liquid with pH test paper, and add appropriate amount of sodium hydroxide or hydrofluoric acid according to the actual situation to adjust the pH of the synthetic liquid to 7, e. Maintain the temperature at 70℃, stir at 18-20r / min for 1h, and obtain large-particle sodium fluoride through centrifugation, drying and screening processes.
2. The method for preparing large-particle sodium fluoride according to claim 1, characterized in that: In step b, the liquid level and weighing reading of the acid and alkali metering tank are monitored throughout the liquid inlet process to avoid liquid leakage.
3. The method for preparing large-particle sodium fluoride according to claim 1, characterized in that: In the step c, the temperature is kept at 70° C. throughout the synthesis, and the pH value is controlled at 6-7.