Preparation method for preventing ammonium bifluoride from caking
By controlling the reaction conditions and drying process during the preparation process of ammonium hydrogen fluoride, the problem of ammonium hydrogen fluoride prone to agglomeration in traditional processes is solved, the storage time is extended, the product purity and stability is improved, and the production cost is reduced.
Patent Information
- Application Number
- CN202411792961.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-08
- Publication Date
- 2025-03-18
AI Technical Summary
In traditional processes, ammonium hydrogen fluoride has high moisture content, is prone to agglomeration, and cannot be stored for a long time. The use of anti-caking agents will increase production costs and affect product quality.
By controlling the temperature and pH value in the reactor, cooling water is used, and a combination of fluidized bed and air-cooled cooling furnace is used during the drying process, the introduction of condensate water is reduced and the agglomeration period of ammonium hydrogen fluoride is extended.
It significantly extends the storage time of ammonium hydrogen fluoride, improves the purity and stability of the product, reduces production costs, and avoids the impact of the use of anti-caking agents on product quality.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of preventing ammonium bifluoride from agglomerating, and in particular to a preparation method for preventing ammonium bifluoride from agglomerating. Background Art
[0002] Ammonium bifluoride is an important inorganic fluoride with the appearance of white or colorless transparent rhombic crystals. It is corrosive, easily deliquescent, easily soluble in water, slightly soluble in alcohol, and decomposes in hot water. Ammonium bifluoride is mainly used as an etchant for carved glass, a disinfectant, a preservative, an analytical reagent, an organic synthetic fluorinating agent, a surface treatment agent for silicon steel plates, an oxidant for manufacturing ceramics and aluminum-magnesium alloys, an electroplating solution, and a reagent for extracting rare elements. The main process for producing ammonium bifluoride is to neutralize hydrofluoric acid with liquid ammonia. This method adds anhydrous hydrogen fluoride and liquid ammonia into a reactor containing high-purity water, evaporates and concentrates, cools, crystallizes, and centrifuges to obtain the finished ammonium bifluoride. In addition, the fluorosilicic acid-liquid ammonia method and the fluorine-containing waste liquid-liquid ammonia method are also used to prepare ammonium bifluoride.
[0003] Although the traditional process requires simple equipment, is easy to control, and has low cost, the product has a high water content, is easy to agglomerate, and cannot be stored for a long time. If anti-caking agents such as polyvinyl alcohol, fatty acid salts, polyethylene glycol, liquid paraffin, soluble silane, and quaternary ammonium salts are selected, the production cost will increase and the product quality will be affected. Therefore, it is particularly important to design a preparation method for preventing ammonium bifluoride from agglomerating to solve the above technical problems. Summary of the invention
[0004] The invention provides a method for preventing ammonium bifluoride from agglomerating in order to solve the problems that the traditional process product has high water content, is easy to agglomerate and cannot be stored for a long time, and if anti-caking agents such as polyvinyl alcohol, fatty acid salt, polyethylene glycol, liquid paraffin, soluble silane, quaternary ammonium salt and the like are used, the production cost will be increased and the product quality will be affected.
[0005] In order to achieve the above object, the present invention adopts the following technical scheme: a preparation method for preventing ammonium bifluoride from agglomerating, comprising the following steps: a. adding 1800kg of high-purity water to a reactor, adding 2300kg of anhydrous hydrogen fluoride and 1300kg of liquid ammonia, controlling the reactor temperature to be 70-95°C and the pH to be 3-4 during the feeding process, b. starting stirring to allow the reactor to fully react, controlling the reactor temperature to be 70-100°C and the pH to be 3-4 during the synthesis process, c. when the reactor temperature exceeds 100°C, introducing cooling water of less than 0.2MPa to cool the reactor, and delivering the synthesized ammonium bifluoride to a thickener through a delivery pump, d. shortening the fluidized bed hot air inlet pipe from 5m to 2m, increasing the heat exchange area of the fluidized bed heat exchanger from 4㎡ to 6㎡, adjusting the vibration amplitude of the vibrating screen, and increasing the material drying time, e. changing the secondary drying rotary kiln into an air-cooled cooling furnace, cooling the high-temperature material to below 40℃, vibrating and screening, and obtaining the finished ammonium bifluoride product.
[0006] Preferably, in step c, the thickener state is confirmed during the cooling process, and then the pipeline is fully preheated.
[0007] Preferably, the purity of the finished ammonium bifluoride product reaches ≥99.5% after testing, the ignition residue reaches ≤0.05%, and it does not agglomerate after being placed for 30 days.
[0008] Compared with the prior art, the advantages and positive effects of the present invention are that, in the present invention, the first half of the drying drum is kept in fluidized bed drying mode, and the second half is changed from rotary kiln heating to air cooling of the rotary kiln heat exchanger, and the induced draft of the rotary kiln is increased at the same time, thereby reducing the material temperature and avoiding the introduction of condensed water. The ammonium bifluoride caking cycle is extended from the original 3-5 days to more than 30 days. Compared with the traditional preparation method, the air cooling and cooling process significantly extends the storage time of the ammonium bifluoride finished product, and the purity is higher, the cost is low, and the stability and reliability are stable. This innovative production technology solves the problem that the traditional process products have high water content, are easy to agglomerate, and cannot be stored for a long time. If anti-caking agents such as polyvinyl alcohol, fatty acid salts, polyethylene glycol, liquid paraffin, soluble silane, and quaternary ammonium salts are used, the production cost will be increased and the product quality will be affected. 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 1800kg of high-purity water to the reactor, add 2300kg of anhydrous hydrogen fluoride and 1300kg of liquid ammonia; control the reactor temperature to 70-95℃ and the pH to 3-4 during the feeding process; start stirring to fully react for 12h, pass cooling water of <0.2MPa, control the reactor temperature to be lower than 100℃, and measure the terminal temperature to be 85℃ and the pH to be 3.5; send the synthesized ammonium bifluoride to the thickener; the high-temperature material is cooled to below 40℃ by the fluidized bed and air-cooled cooling furnace, fully dried, vibrated and screened, and metered and packaged. The yield of the finished ammonium bifluoride is 95.5%, the purity is 99.7%, the ignition residue is 0.03, and it will agglomerate after being placed for 45 days.
[0012] Example 2 The method is basically the same as Example 1, except that the drying process adopts a rotary kiln heating method, and the yield of the ammonium bifluoride product is 88.5%, the purity is 98.3%, the ignition residue is 0.08, and the product is agglomerated after being placed for 17 days.
[0013] Example 3 The method is basically the same as Example 1, except that the reaction temperature is controlled to be 100-120° C., the yield of the ammonium bifluoride product is 89.6%, the purity is 97.8%, the ignition residue is 0.10, and the product agglomerates after being placed for 24 days.
[0014] Example 4 The method is basically the same as Example 1, except that the synthesis time is shortened to 10 h, the yield of the ammonium bifluoride product is 91.3%, the purity is 95.7%, the ignition residue is 0.06, and the product agglomerates after being placed for 23 days.
[0015] Example 5 The method is basically the same as Example 1, except that the synthesis endpoint pH is adjusted to 4.5, the yield of the ammonium bifluoride product is about 93.4%, the purity is 96.2%, the ignition residue is 0.06, and the product is allowed to agglomerate after being placed for 27 days.
[0016] The indicators of the above embodiments are compared as follows: In summary, the preparation scheme to prevent ammonium bifluoride from agglomerating is to keep the first half of the drying drum in fluidized bed drying mode, and change the second half from rotary kiln heating to air cooling of the rotary kiln heat exchanger, while increasing the induced draft of the rotary kiln to reduce the material temperature and avoid the introduction of condensed water. The agglomeration period of ammonium bifluoride is extended from the original 3-5 days to more than 30 days. Compared with traditional preparation methods, the air cooling process significantly extends the storage time of the finished ammonium bifluoride product, and it is an innovative production technology with higher purity, low cost, stability and reliability.
Claims
1. A method for preventing ammonium bifluoride from agglomerating, comprising the following steps, characterized in that: a. Add 1800kg of high-purity water to the reactor, add 2300kg of anhydrous hydrogen fluoride and 1300kg of liquid ammonia, control the reactor temperature at 70-95℃ and PH at 3-4 during the feeding process, b. Start stirring to make it fully react, control the reactor temperature at 70-100℃ and PH at 3-4 during the synthesis process, c. When the reactor temperature exceeds 100℃, introduce cooling water of <0.2MPa to cool it down, and send the synthesized ammonium bifluoride into the thickener through the delivery pump, d. Shorten the fluidized bed hot air inlet pipe from 5m to 2m, increase the heat exchange area of the fluidized bed heat exchanger from 4㎡ to 6㎡, adjust the vibration amplitude of the vibrating screen, and increase the material drying time, e. Change the secondary drying rotary kiln into an air-cooled cooling furnace, cool the high-temperature material to below 40℃, vibrate and screen, and obtain the finished ammonium bifluoride product.
2. The method for preventing ammonium bifluoride from agglomerating according to claim 1, wherein: In the step c, the thickener status is confirmed during the cooling process, and then the pipeline is fully preheated.
3. The method for preventing ammonium bifluoride from agglomerating according to claim 1, wherein: The purity of the finished ammonium bifluoride product is ≥99.5% after testing, the ignition residue is ≤0.05%, and it does not agglomerate after being placed for 30 days.