CN118929696A

CN118929696A - A method for producing electronic grade high-purity sodium fluoride

Info

Publication number: CN118929696A
Application number: CN202411162426.7A
Authority: CN
Inventors: 袁其亮; 鹿威威; 石永根; 徐寅子; 王梓汀; 施正军; 孟惠彪; 李向明
Original assignee: Fujian Zhongxin Fluorine Material Gaobao Technology Co ltd; Zhejiang Zhongxin Fluorine Materials Co ltd
Current assignee: Fujian Zhongxin Fluorine Material Gaobao Technology Co ltd; Zhejiang Zhongxin Fluorine Materials Co ltd
Priority date: 2024-08-23
Filing date: 2024-08-23
Publication date: 2024-11-12

Abstract

本发明公开了一种电子级高纯氟化钠的生产方法，属于无机化学合成技术领域，包括以下操作步骤：(1)将碳酸钠溶解于氟化钠溶液中，经滤膜过滤，得到碳酸钠粗溶液；(2)所得的碳酸钠粗溶液，加入活性炭吸附，经滤膜过滤，得到碳酸钠精溶液；(3)所得的碳酸钠精溶液，经螯合树脂吸附，得到碳酸钠纯溶液；(4)所得的碳酸钠纯溶液与氟化氢经酸碱中和反应、固液分离操作、纯水漂洗操作，得到氟化钠湿品固体和母液；(5)所得的母液经纳滤除杂，得到纯化母液，作为氟化钠溶液，用于配置碳酸钠溶液；(6)所得的氟化钠湿品固体经干燥，得到电子级高纯氟化钠。该方法以工业碳酸钠为原料生产电子级高纯氟化钠，具有简单高效、绿色低耗、质优价廉等优点。The invention discloses a production method of electronic grade high-purity sodium fluoride, which belongs to the technical field of inorganic chemical synthesis, and comprises the following steps: (1) dissolving sodium carbonate in a sodium fluoride solution, filtering through a filter membrane, and obtaining a crude sodium carbonate solution; (2) adding activated carbon to the obtained crude sodium carbonate solution for adsorption, filtering through a filter membrane, and obtaining a refined sodium carbonate solution; (3) adsorbing the obtained refined sodium carbonate solution through a chelating resin, and obtaining a pure sodium carbonate solution; (4) subjecting the obtained pure sodium carbonate solution to an acid-base neutralization reaction, a solid-liquid separation operation, and a pure water rinsing operation to obtain a sodium fluoride wet solid and a mother liquor; (5) removing impurities from the obtained mother liquor through nanofiltration, and obtaining a purified mother liquor as a sodium fluoride solution for preparing a sodium carbonate solution; (6) drying the obtained sodium fluoride wet solid to obtain electronic grade high-purity sodium fluoride. The method uses industrial sodium carbonate as a raw material to produce electronic grade high-purity sodium fluoride, and has the advantages of being simple, efficient, green, low-consumption, high-quality, and low-cost.

Description

Production method of electronic grade high-purity sodium fluoride

Technical Field

The invention belongs to the technical field of inorganic chemical synthesis, in particular to a method for producing sodium fluoride, and particularly relates to a method for producing electronic grade high-purity sodium fluoride by taking industrial sodium carbonate as a raw material.

Background

Sodium fluoride is a very important inorganic chemical and has important applications in the fields of industry, agriculture, forestry, health, etc. In the industrial field, sodium fluoride can be used as a metal surface treating agent in the metallurgical industry for etching and degreasing, removing oxide and dirt on the metal surface, improving the smoothness and adhesiveness of the metal surface, can also be used as a fluorinating agent or a catalyst in the chemical industry for synthesizing various fine chemicals, can also be used for preparing fluoride fuel, fluoride liquid and the like in the nuclear industry, and can be used as fuel and coolant of a nuclear reactor; in the agriculture and forestry field, sodium fluoride can be used as a wood preservative to improve the durability of wood, and can also be used as an insecticide and a bactericide; in the field of health, sodium fluoride can be used for preparing fluorine-containing toothpaste, mouthwash and the like, preventing dental caries and dental plaque from forming, and enhancing the corrosion resistance of teeth.

In recent years, as new energy demands are increased, lithium batteries are rapidly developed, but sodium batteries are receiving attention due to limitations of lithium resources and safety of lithium batteries. The reserve of sodium element in crust is nearly 500 times of that of lithium element, and the sodium resource is widely and uniformly distributed worldwide, so the acquisition cost and convenience of the sodium resource have natural advantages compared with the lithium resource. In addition, the sodium battery also shows higher use safety and better low-temperature cycle performance, and has strong competitiveness in the future new energy field.

Sodium fluoride is used as a key raw material in the sodium battery manufacturing field, has higher requirements on product quality compared with other fields, has high requirements on main content, and has strict limitation on residual trace hetero metal cations and hetero anions. Sodium fluoride is currently synthesized by a fluosilicic acid method, the content of impurities in fluosilicic acid is high, silicon dioxide is generated in the synthesis process, so that the quality of sodium fluoride is relatively low, and the sodium fluoride can be used in the fields of common industry, agriculture, forestry and health, but cannot meet the high-quality requirements of the sodium battery field. In order to produce high-purity sodium fluoride, sodium carbonate and hydrogen fluoride are commonly selected as raw materials in the industry, and acid-base neutralization reaction is carried out to produce the battery-grade high-purity sodium fluoride.

The key element of the acid-base neutralization method for preparing high-purity sodium fluoride is to control the quality of raw materials sodium carbonate and hydrogen fluoride, and the content of mixed cations such as potassium, calcium, iron, magnesium and the like and mixed anions such as chloride ions, sulfate ions and the like in the raw materials is controlled in a reasonable range through purifying the sodium carbonate and the hydrogen fluoride. However, too complicated purification methods and purification processes will lead to a significant increase in production costs, and therefore, how to produce sodium fluoride of optimal quality at the lowest cost is an important point in the industry.

For example, chinese patent application CN115893449 discloses a method for producing electronic grade sodium fluoride from industrial grade sodium-alkali mixed solution, which comprises the following steps: (1) Preparing sodium carbonate/sodium hydroxide mixed alkali solution, stirring, standing and filtering solid impurities in the mixed alkali solution; (2) Adding oxalic acid into the mixed alkali solution, stirring, standing, and filtering by using a micron-sized filter membrane; (3) Adding a trace amount of EDTA reagent into the mixed alkali solution, stirring, adding activated carbon for adsorption, and filtering by a micron-sized filter membrane; (4) Centrifuging the mixed alkali solution, and taking supernatant as synthetic alkali liquor; (5) Introducing the purified sodium alkali solution into a salt pond, heating and concentrating, blowing hydrogen fluoride gas into the solution and excessively adding sodium carbonate purification solution to adjust the pH of the solution, and stirring until the reaction is finished; (6) And cooling the salt pond to room temperature to generate sodium fluoride crystals, filtering and drying to obtain a high-purity sodium fluoride product. Although the sodium fluoride product with higher purity is prepared by the method, the main metal ion content is controlled below 50ppm, the operation process is complex, and reagents such as oxalic acid, EDTA and the like are additionally added, so that the use of the reagents not only increases the production cost, but also increases the pollution risk of sodium fluoride, and potential hazards are caused to the safety application of sodium fluoride in the downstream sodium battery field. For example, chinese patent application CN116654954 discloses a method for preparing sodium fluoride, which comprises the following steps: (1) Carrying out impurity removal pretreatment on a sodium source to obtain the sodium source after impurity removal; (2) Mixing hydrogen fluoride with the sodium source subjected to impurity removal in the step (1), reacting, and then carrying out solid-liquid separation to obtain a sodium fluoride wet material; (3) And (3) dissolving the wet sodium fluoride material obtained in the step (2) to obtain a sodium fluoride solution, and then performing impurity removal post-treatment to obtain the sodium fluoride. The sodium fluoride synthesized by the method has low residual quantity of calcium, iron and magnesium ions, but other ions which are easy to pollute the quality of the sodium fluoride, such as potassium ions, sulfate ions and the like, are not detected, so that whether the requirement of the battery-level sodium fluoride is met cannot be judged. In addition, the method uses hydrogen peroxide as a impurity removing agent, although the risk of polluting sodium fluoride is relatively small, the hydrogen peroxide belongs to a high-safety-risk chemical, the safety risk of the production process is unintentionally increased, and meanwhile, the method also needs operations such as redissolving and impurity removing of sodium fluoride wet materials, concentrating and crystallizing again, and the like, has complex operation procedures and higher energy consumption, and does not meet the low-carbon production requirement.

Therefore, in the field of electronic grade high purity sodium fluoride production and manufacture, a great number of practical problems still need to be solved. Along with the gradual release of the demand of sodium batteries, development of a method for preparing electronic grade high-purity sodium fluoride by taking low-cost and easily-obtained industrial grade sodium carbonate as a raw material and adopting simple, efficient, green and low-consumption production procedures is urgently needed.

Disclosure of Invention

Aiming at the defects existing in the field of electronic grade high-purity sodium fluoride manufacturing, the invention provides a method for manufacturing electronic grade high-purity sodium fluoride, which takes industrial sodium carbonate as a raw material and is simple, efficient, green, low in consumption, high in quality, low in cost and the like through the procedures of dissolving, micro-filtering for impurity removal, adsorption for impurity removal, acid-base reaction, nano-filtering for impurity removal, drying and the like.

The technical scheme adopted by the invention is as follows:

The production method of the electronic grade high-purity sodium fluoride is characterized by comprising the following steps of:

(1) Dissolving sodium carbonate in a sodium fluoride solution, and filtering by a filter membrane to obtain a sodium carbonate crude solution (I);

(2) Adding active carbon into the crude sodium carbonate solution (I) obtained in the step (1) for adsorption, and filtering by a filter membrane to obtain a refined sodium carbonate solution (II);

(3) Adsorbing the sodium carbonate refined solution (II) obtained in the step (2) by chelating resin to obtain a sodium carbonate pure solution (III);

(4) Neutralizing the sodium carbonate pure solution (III) obtained in the step (3) with hydrogen fluoride through acid-base, performing solid-liquid separation operation and performing pure water rinsing operation to obtain sodium fluoride wet product solid (IV) and mother liquor (V);

(5) Removing impurities from the mother solution (V) obtained in the step (4) by nanofiltration to obtain a purified mother solution (VI) which is used as a sodium fluoride solution for preparing a sodium carbonate solution in the operation (1);

(6) And (3) drying the wet sodium fluoride solid (IV) obtained in the step (4) to obtain the electronic grade high-purity sodium fluoride (VII).

The synthetic route adopted by the invention can be represented by the following reaction formula:

Na₂CO₃+2HF→2NaF+CO₂+H₂O。

The invention is further provided as follows:

In step (1):

The sodium carbonate is common industrial grade sodium carbonate, the sodium carbonate content is more than or equal to 99.0 percent, other sodium carbonate has no special requirements, and the conventional market selling price is 2000-3000 yuan/ton.

The mass content of the sodium fluoride in the sodium fluoride solution is 0-5.0%. The sodium fluoride solution can be prepared by adopting sodium fluoride solid and water according to a certain proportion, or can be purified mother liquor obtained by solid-liquid separation and nanofiltration impurity removal after acid-base neutralization reaction in the production process, and preferably the sodium fluoride solution is the purified mother liquor containing sodium fluoride produced in the production process.

The filter membrane is a microporous filter membrane with the aperture of 0.05-2.0 microns, and the aperture of the filter membrane is preferably 0.1-1.0 microns. For the purpose of filtration by a filter membrane, besides removing mechanical impurities in the sodium carbonate solution, macromolecular compounds, micelles and other insoluble substances in the sodium carbonate solution can be primarily removed.

The mass concentration of sodium carbonate in the sodium carbonate crude solution is 1.0-32.0%, and the mass concentration of the sodium carbonate crude solution is 10.0-32.0%.

The operating temperature of the step (1) is 0-100 ℃.

In the step (2):

The active carbon is powdery active carbon with the particle size of 100-1000 meshes, and the particle size of the active carbon is preferably 300-800 meshes. The activated carbon may be industrial-grade activated carbon or food-grade activated carbon, or electronic-grade activated carbon, and is preferably selected from the viewpoints of reducing the processing load of the subsequent chelating resin adsorption process and mother liquor nanofiltration impurity removal process, and improving the product quality. The dosage of the activated carbon is 0.01 to 20.0 percent of the weight of the sodium carbonate contained in the sodium carbonate crude solution (I).

The purpose of using the activated carbon is to adsorb small micelles and macromolecular compounds which have relatively small size and are easy to permeate through a microporous filter membrane in the crude sodium carbonate solution (I). These impurities are filtered out together with the activated carbon by activated carbon adsorption and filtration through microporous membranes. The activated carbon adsorption process is preferably performed in a stirred state to accelerate the adsorption speed and deepen the adsorption progress.

The filter membrane is a microporous filter membrane with the aperture of 0.05-2.0 microns, and the aperture of the filter membrane is preferably 0.1-1.0 microns. For the purpose of filtration by a filter membrane, macromolecular compounds, micelles and other insoluble substances in the sodium carbonate solution can be further removed besides the adsorbent activated carbon.

The operating temperature of the step (2) is 0-100 ℃.

In view of the approximation of the operating conditions of step (1) and step (2), step (1) and step (2) may be performed in combination from the viewpoint of simplifying the process, such as: dissolving sodium carbonate in sodium fluoride solution to obtain sodium carbonate crude solution (I), adding activated carbon for adsorption, and filtering with a filter membrane to obtain sodium carbonate refined solution (II).

In the operation step (3):

the chelating resin is one or two selected from amino carboxylic acid type chelating resin and amino phosphoric acid type chelating resin. The purpose of the chelate resin adsorption treatment of the sodium carbonate refined solution (II) is to remove the metal cations with the valence of 2 and above in the sodium carbonate refined solution (II) by utilizing the selective chelation of the chelate resin on the metal cations with the valence of 2 and above so as to achieve the purpose of purifying the sodium carbonate solution. The adsorption process can adopt a soaking method, namely, a certain amount of chelate resin is soaked in sodium carbonate refined solution (II), and after soaking and adsorbing for a certain time, the chelate resin is separated by filtration, so as to obtain sodium carbonate pure solution (III). In actual operation, in order to improve the adsorption effect of the chelate resin and simplify the operation flow, the chelate resin is preferably pre-filled into a tower with a certain length-diameter ratio to prepare a resin adsorption tower, and then the sodium carbonate refined solution (II) slowly flows through the resin tower in a top-down or top-down mode, so that the faster and better adsorption impurity removal effect is realized.

The amount of the chelating resin can be measured by measuring the adsorption capacity of the chelating resin and the content of 2-valent metal cations in the sodium carbonate refined solution (II) and more, after setting a reasonable safety coefficient, the proportion of the chelating resin to the sodium carbonate refined solution (II) is calculated, for example, the amount of the chelating resin required for treating a certain amount of the sodium carbonate refined solution (II) or the amount of the sodium carbonate refined solution (II) treated by a certain amount of the chelating resin is calculated, and the rationality and the treatment effect are set by detecting the residual amount of metal ions in the sodium carbonate refined solution (III) obtained after adsorption.

The chelating resin needs to be pretreated before use, and needs to be activated and regenerated after use so as to recover the optimal adsorption performance of the chelating resin. The pretreatment process and the activation regeneration process have certain similarity, and comprise the processes of dilute hydrochloric acid replacement, pure water washing, dilute sodium hydroxide solution replacement, pure water washing and the like, and specific process parameters are slightly different from the resin model of chelating resin manufacturers and are required to be specifically determined in actual use.

The operating temperature of step (3) is 0 to 80 ℃, preferably 20 to 60 ℃.

In the step (4):

The hydrogen fluoride is selected from one or more of the following: hydrogen fluoride gas, anhydrous hydrogen fluoride liquid, and aqueous hydrogen fluoride solution. The concentration of hydrogen fluoride in the aqueous hydrogen fluoride solution is 1.0 to 50.0% by mass, and preferably 10.0 to 49.0% by mass. The hydrogen fluoride may be industrial grade hydrogen fluoride or electronic grade hydrogen fluoride, and the electronic grade hydrogen fluoride is preferable as the hydrogen fluoride for the reaction from the viewpoints of improving the product quality and reducing the subsequent impurity treatment load of the mother liquor nanofiltration.

The amount of hydrogen fluoride theoretically required is 2.0 equivalents of sodium carbonate material in the pure sodium carbonate solution (III). The control of the reaction end point, except the control of the mixture ratio of the reaction materials, the end point is confirmed by combining the pH value of the reaction liquid, and the pH value of the reaction liquid is controlled to be 6-8 when the reaction end point is controlled, so that the acid and the alkali in the reaction liquid can fully react.

The sodium carbonate pure solution (III) and the hydrogen fluoride can be fed into the hydrogen fluoride, or the hydrogen fluoride can be fed into the sodium carbonate pure solution (III), or both can be fed simultaneously according to the designed material proportion. The preferred feeding mode is as follows: the sodium carbonate pure solution (III) and hydrogen fluoride are mixed according to the respective concentration and the amount of the substances combined with the reaction, the volume or weight ratio of the sodium carbonate pure solution (III) and the hydrogen fluoride is calculated, and the sodium carbonate pure solution and the hydrogen fluoride are simultaneously added according to the ratio.

The acid-base neutralization reaction can be carried out in a reaction kettle or in a continuous microreactor or a tubular reactor, and the reaction temperature is 0-100 ℃.

The reaction solution obtained by the neutralization reaction of the pure sodium carbonate solution (III) and the hydrogen fluoride through acid and alkali has small solubility of the product sodium fluoride, and generally, a large amount of sodium fluoride solids are separated out to form a solid-liquid mixed state, so that the solid-liquid separation operation can be directly carried out. In order to obtain a product with higher yield and better quality, the reaction liquid can be collected, cured and crystallized under certain conditions, and then subjected to solid-liquid separation.

The sodium fluoride obtained by solid-liquid separation of the reaction liquid may have a certain influence on the product quality due to the surface being stained with a part of mother liquor, and in view of the small solubility of sodium fluoride, a proper amount of pure water can be used for rinsing the solid to improve the product quality, and the rinsing liquid formed by rinsing the pure water is combined with the reaction mother liquor to obtain the mother liquor (V). The pure water rinsing operation is helpful for improving the quality of the product, but is not necessary, and in actual production, whether the pure water rinsing operation is performed or not, the quantity of pure water for rinsing, the rinsing mode and the like can be determined according to the quality requirement of the product.

In the step (5):

The nanofiltration refers to the operation of purifying the mother solution (V) by using a membrane filtration device with the pore diameter of a filter membrane between 1 and 10nm and the molecular weight cut-off between 100 and 1000, which is suitable for separating low molecular weight organic matters from inorganic salts. The purpose of nano-filtration and impurity removal of the mother solution (V) is to remove relatively large-molecular-weight hetero anions such as sulfate radical, phosphate radical and the like contained in the mother solution, avoid the accumulation of the hetero anions in the mother solution, remove residual cations with valence of 2 and above and partial potassium ions in the mother solution, and ensure that the quality of the mother solution meets the application requirement.

The nanofiltration system will produce a certain amount of nanofiltration effluent while preparing the purified mother liquor (VI). The nanofiltration drainage is not sewage without any purpose, but is a sodium fluoride solution which has higher impurity anion and cation contents than the purification mother liquor (VI) and cannot be directly used for preparing electronic grade sodium fluoride, but still meets the requirements for preparing industrial grade sodium fluoride, so the nanofiltration drainage can be recycled for preparing industrial grade sodium fluoride, or is used for producing electronic grade sodium fluoride after impurity removal and purification, and the preferred nanofiltration drainage treatment mode is co-production of industrial grade sodium fluoride.

In consideration of the precision of the nanofiltration system, the mother solution is easy to be polluted by macromolecular micelles, so that in actual use, a microfiltration system, an ultrafiltration system and the like are additionally arranged before the nanofiltration system and are used as components of a nanofiltration device, so that the anti-pollution capability of the nanofiltration system is enhanced and the service life is prolonged.

The operating temperature of step (5) is 0 to 80℃and preferably 20 to 60 ℃.

In the step (6):

The drying refers to removing the water in the wet sodium fluoride product by heating, decompressing and the like so as to meet the quality requirement of the electronic grade high-purity sodium fluoride.

The drying mode may be normal pressure drying or reduced pressure drying, and the drying temperature is in the range of 0-200 ℃, preferably 50-150 ℃.

The yield of the electronic grade high-purity sodium fluoride (VII) obtained by drying is more than 90 percent, the content of sodium fluoride is more than or equal to 99.97 percent, the moisture is less than or equal to 100ppm, the K is less than or equal to 3ppm, the calcium is less than or equal to 3ppm, the iron is less than or equal to 3ppm, the magnesium is less than or equal to 3ppm, the zinc is less than or equal to 3ppm, the aluminum is less than or equal to 3ppm, arsenic less than or equal to 3ppm, lead less than or equal to 1ppm, chromium less than or equal to 1ppm, cadmium less than or equal to 1ppm, nickel less than or equal to 1ppm, manganese less than or equal to 1ppm, copper less than or equal to 1ppm, silicon less than or equal to 10ppm, sulfate less than or equal to 10ppm, phosphate less than or equal to 1ppm, nitrate less than or equal to 5ppm, and chloride less than or equal to 10ppm.

Compared with the prior art, the invention has the beneficial effects that:

(1) The electronic grade high-purity sodium fluoride is prepared from industrial sodium carbonate serving as a raw material through the procedures of dissolving, micro-filtration and impurity removal, adsorption and impurity removal, acid-base reaction, nanofiltration and impurity removal, drying and the like, and is simple and efficient, green and low in consumption, and high in quality and low in cost;

(2) No chemical reagent is used in the manufacturing process, so that the pollution of an exogenous additive to a product is avoided, the production cost is reduced, the operation flow is simplified, and the safety of the production process is improved;

(3) The manufacturing process does not involve high energy consumption operation procedures such as solution distillation concentration, solid dissolution/recrystallization and the like, has low energy consumption, and accords with the green low-carbon production concept;

(4) The yield of the manufactured electronic grade high-purity sodium fluoride product is more than 90 percent, the content of the electronic grade high-purity sodium fluoride product is more than or equal to 99.97 percent, the content of each impurity anion and each impurity cation is low, and the electronic grade high-purity sodium fluoride product has excellent quality in the specification of the battery grade sodium fluoride product.

(5) Simultaneously, the electronic grade high-purity sodium fluoride is produced, and the industrial grade sodium fluoride is co-produced, the combined yield of the two is close to 100%, so that the full utilization of resources is realized.

The invention is further illustrated by the following detailed description. The following embodiments are only for aiding in understanding the present invention, and are not to be construed as limiting the present invention. The specific embodiments cannot be used to distinguish all technical features of the present invention, and as long as the technical features referred to in the specification do not conflict with each other, all the technical features can be combined with each other to form a new embodiment.

Detailed Description

Example 1

2000 Kg of purified mother solution (VI) is added into a 3000-liter reaction kettle A, the mixture is stirred at room temperature, 500 kg of industrial sodium carbonate is added, the mixture is stirred at room temperature for 1 hour after the addition is finished, a sodium carbonate solution is conveyed to a filter membrane filter provided with a 0.45-micrometer filter membrane by a pump, and filtrate filtered by the filter membrane is collected in a storage tank A to obtain a sodium carbonate crude solution (I).

2500 Kg of crude sodium carbonate solution (I) is added into a 3000-liter reaction kettle B, 5kg of 500-mesh active carbon is added, the mixture is stirred for 2 hours at room temperature, the mixture is conveyed into a filter membrane filter provided with a filter membrane with 0.45 micron size, and the filtrate filtered by the filter membrane is collected in a storage tank B to obtain refined sodium carbonate solution (II).

The resin tower filled with aminocarboxylic acid type chelating resin is subjected to dilute hydrochloric acid replacement, pure water cleaning, dilute sodium hydroxide solution replacement and pure water cleaning respectively to complete the activation of the chelating resin. 2500 kg of sodium carbonate refined solution (II) is conveyed to a chelating resin tower through a pump at the temperature of 60 ℃, flows through the chelating resin tower from top to bottom at the speed of 1BV/h, and purified solution after being adsorbed by the chelating resin is collected in a storage tank C to obtain sodium carbonate pure solution (III).

Adding 100 kg of purified mother liquor (VI) as bottoming liquid into a 4000L reaction kettle C, stirring and heating to 70 ℃, simultaneously adding 2500 kg of sodium carbonate pure solution (III) and 539.4 kg of 35% hydrogen fluoride solution into the reaction kettle by a metering pump, detecting the pH value of the reaction liquid to be 7.2 after the addition, carrying out heat preservation and stirring on the reaction liquid at 70 ℃ for 1 hour, cooling to room temperature, carrying out centrifugal separation and rinsing by pure water to obtain sodium fluoride wet product solid (IV), combining the centrifugal mother liquor and rinsing liquid to obtain mother liquor (V), and collecting the mother liquor (V) in a storage tank D.

The mother solution (V) in the storage tank D is conveyed to a nanofiltration device through a pump, and purified mother solution (VI) is obtained after nanofiltration and impurity removal, and is collected in a storage tank E for preparing sodium carbonate solution; draining water from the nanofiltration device to prepare industrial sodium fluoride.

The wet sodium fluoride solid (IV) is added into a bipyramid dryer and dried for 16 hours at 90 ℃ under reduced pressure to obtain 366.8 kg of electronic grade high-purity sodium fluoride (VII), the yield is 92.6%, and the detection result is shown in the attached table.

Example 2

Adding 1680 kg of purified mother liquor (VI) into a 3000-liter reaction kettle A, stirring and heating to 50 ℃, adding 720 kg of industrial sodium carbonate, stirring at 50 ℃ for 2 hours after the addition, pumping the sodium carbonate solution while the sodium carbonate solution is hot to a filter membrane filter provided with a 0.2-micrometer filter membrane, and collecting the filtrate after filtration by the filter membrane into a storage tank A to obtain a crude sodium carbonate solution (I).

Adding 2400 kg of crude sodium carbonate solution (I) into a 3000-liter reaction kettle B, adding 4 kg of 800-mesh active carbon, stirring and heating, preserving heat and stirring for 1 hour at 70 ℃, conveying the mixed solution to a filter membrane filter with a 0.3-micrometer filter membrane by a pump, and collecting filtrate after filtration by the filter membrane in a storage tank B to obtain refined sodium carbonate solution (II).

The resin tower filled with the aminophosphoric acid type chelating resin is subjected to dilute hydrochloric acid replacement, pure water cleaning, dilute sodium hydroxide solution replacement and pure water cleaning respectively to complete the activation of the chelating resin. 2400 kg of sodium carbonate refined solution (II) is conveyed to a chelating resin tower through a pump at room temperature, flows through the chelating resin tower from top to bottom at a speed of 5BV/h, and purified solution after being adsorbed by the chelating resin is collected in a storage tank C to obtain sodium carbonate pure solution (III).

2400 Kg of pure sodium carbonate solution (III) is added into a 4000L reaction kettle C, stirring is carried out at room temperature, 271.9 kg of anhydrous hydrogen fluoride liquid is slowly added, after the addition is finished, the pH of the reaction liquid is detected to be 6.8, the reaction liquid is subjected to centrifugal separation and pure water rinsing to obtain wet sodium fluoride product solid (IV), the centrifugal mother solution is combined with the rinsing liquid to obtain mother solution (V), and the mother solution is collected in a storage tank D.

Adding the wet sodium fluoride solid (IV) into a box dryer, and drying at 120 ℃ and normal pressure for 12 hours to obtain 537.5 kg of electronic grade high-purity sodium fluoride (VII), wherein the yield is 94.2%, and the detection result is shown in the attached table.

Example 3

Adding 1800 kg of purified mother liquor (VI) into a 3000-liter reaction kettle A, stirring and heating to 70 ℃, adding 600 kg of industrial sodium carbonate, stirring at 70 ℃ for 1 hour after the addition, pumping the sodium carbonate solution while the sodium carbonate solution is hot to a filter membrane filter provided with a 0.1-micrometer filter membrane, and collecting the filtrate filtered by the filter membrane into a storage tank A to obtain a crude sodium carbonate solution (I).

2400 Kg of crude sodium carbonate solution (I) is added into a 3000-liter reaction kettle B, 40 kg of 300-mesh active carbon is added, stirring and heating are carried out, heat preservation and stirring are carried out at 50 ℃ for 2 hours, the mixed solution is conveyed into a filter membrane filter with a 1.0-micrometer filter membrane by a pump, and the filtrate after filtration by the filter membrane is collected in a storage tank B, so as to obtain refined sodium carbonate solution (II).

The resin tower filled with aminocarboxylic acid type chelating resin is subjected to dilute hydrochloric acid replacement, pure water cleaning, dilute sodium hydroxide solution replacement and pure water cleaning respectively to complete the activation of the chelating resin. 2400 kg of sodium carbonate refined solution (II) is conveyed to a chelating resin tower through a pump, flows through the chelating resin tower from top to bottom at the speed of 4BV/h, and purified solution after being adsorbed by the chelating resin is collected in a storage tank C to obtain sodium carbonate pure solution (III).

Adding 100 kg of purified mother liquor (VI) as bottoming liquid into a 4000L reaction kettle C, stirring and heating to 50 ℃, simultaneously adding 2400 kg of sodium carbonate pure solution (III) and 566.3 kg of 40% hydrogen fluoride solution into the reaction kettle by a metering pump, detecting the pH of the reaction liquid to be 7.6 after the addition, keeping the temperature of the reaction liquid at 50 ℃ for curing for 2 hours, cooling to room temperature, stirring and crystallizing for 2 hours, centrifugally separating the reaction liquid, rinsing by pure water to obtain sodium fluoride wet product solid (IV), combining the centrifugally separated mother liquor with rinsing liquid to obtain mother liquor (V), and collecting the mother liquor in a storage tank D.

Adding the wet sodium fluoride solid (IV) into a single cone dryer, drying at 70 ℃ under reduced pressure for 24 hours to obtain 442.2 kg of electronic grade high-purity sodium fluoride (VII), wherein the yield is 93.0%, and the detection result is shown in the attached table.

Example 4

Adding 1656 kg of purified mother liquor (VI) into a 3000-liter reaction kettle A, stirring and heating to 80 ℃, adding 644 kg of industrial sodium carbonate, stirring at 80 ℃ for 2 hours after the addition, pumping the sodium carbonate solution while the sodium carbonate solution is hot to a filter membrane filter provided with a 1.0-micrometer filter membrane, and collecting filtrate filtered by the filter membrane into a storage tank A to obtain a crude sodium carbonate solution (I).

Adding 2300 kg of crude sodium carbonate solution (I) into a 3000-liter reaction kettle B, adding 14 kg of 400-mesh active carbon, stirring and heating, preserving heat and stirring for 1 hour at 80 ℃, conveying the mixed solution to a filter membrane filter with a 0.1-micrometer filter membrane by a pump, and collecting filtrate after filtration by the filter membrane in a storage tank B to obtain refined sodium carbonate solution (II).

The resin tower filled with the aminophosphoric acid type chelating resin is subjected to dilute hydrochloric acid replacement, pure water cleaning, dilute sodium hydroxide solution replacement and pure water cleaning respectively to complete the activation of the chelating resin. 2300 kg of sodium carbonate refined solution (II) is conveyed to a chelating resin tower through a pump, flows through the chelating resin tower from top to bottom at the speed of 2BV/h, and purified solution absorbed by the chelating resin is collected in a storage tank C to obtain sodium carbonate pure solution (III).

Adding 100 kg of purified mother liquor (VI) as bottoming liquid into a 4000L reaction kettle C, stirring and heating to 50 ℃, simultaneously adding 2300 kg of sodium carbonate pure solution (III) and 496.3 kg of 49% electronic grade hydrogen fluoride solution into the reaction kettle by a metering pump, detecting the pH of the reaction liquid to be 6.9 after the addition, cooling the reaction liquid to room temperature, centrifugally separating, rinsing by pure water to obtain sodium fluoride wet product solid (IV), combining the centrifugally separated mother liquor and rinsing liquid to obtain mother liquor (V), and collecting the mother liquor (V) in a storage tank D.

Adding the wet sodium fluoride solid (IV) into a single cone dryer, and drying at 60 ℃ under reduced pressure for 30 hours to obtain 477.1 kg of electronic grade high-purity sodium fluoride (VII), wherein the yield is 93.5%, and the detection result is shown in the attached table.

Example 5

Adding 1680 kg of purified mother liquor (VI) into a 3000-liter reaction kettle A, stirring and heating to 40 ℃, adding 720 kg of industrial sodium carbonate, stirring for 1 hour at 40 ℃ after the addition, adding 11 kg of 600-mesh active carbon, continuously stirring for 2 hours at 40 ℃, conveying the mixed liquor to a filter membrane filter provided with a 0.3-micrometer filter membrane by a pump, and collecting the filtrate filtered by the filter membrane into a storage tank B to obtain a sodium carbonate refined solution (II).

The resin tower filled with aminocarboxylic acid type chelating resin is subjected to dilute hydrochloric acid replacement, pure water cleaning, dilute sodium hydroxide solution replacement and pure water cleaning respectively to complete the activation of the chelating resin. 2400 kg of sodium carbonate refined solution (II) is conveyed to a chelating resin tower through a pump at the temperature of 40 ℃, flows through the chelating resin tower from top to bottom at the speed of 3BV/h, and purified solution after being adsorbed by the chelating resin is collected in a storage tank C to obtain sodium carbonate pure solution (III).

2400 Kg of pure sodium carbonate solution (III) is added into a 4000L reaction kettle C, the stirring temperature is controlled at 40 ℃, 271.8 kg of hydrogen fluoride gas is slowly introduced, after the addition, the pH of the reaction liquid is detected to be 7.7, the reaction liquid is stirred for 2 hours at the temperature of 40 ℃, the solid (IV) of wet sodium fluoride is obtained through centrifugal separation and rinsing with pure water, the centrifugal mother liquid is combined with the rinsing liquid to obtain mother liquid (V), and the mother liquid is collected in a storage tank D.

Adding the wet sodium fluoride solid (IV) into a bipyramid dryer, drying at 80 ℃ under reduced pressure for 20 hours to obtain 543.2 kg of electronic grade high-purity sodium fluoride (VII), wherein the yield is 95.2%, and the detection result is shown in the attached table.

Product inspection

The detection method comprises the following steps: ICP-OES method, ion chromatography, and Karl Fischer coulomb method. The results of the product testing are shown in the following table.

The attached table:

Analysis:

As shown in the table above, the electronic grade high-purity sodium fluoride product manufactured by the invention has the yield of more than 90 percent, the content of more than or equal to 99.97 percent, and the content of each impurity anion and each impurity cation is low, and the electronic grade high-purity sodium fluoride product has excellent quality in the specification of the battery grade sodium fluoride product.

Claims

1. The production method of the electronic grade high-purity sodium fluoride is characterized by comprising the following steps of:

(1) Dissolving sodium carbonate in a sodium fluoride solution, and filtering by a filter membrane to obtain a sodium carbonate crude solution;

(2) Adding activated carbon into the crude sodium carbonate solution obtained in the step (1) for adsorption, and filtering the solution through a filter membrane to obtain a refined sodium carbonate solution;

(3) Adsorbing the sodium carbonate refined solution obtained in the step (2) by chelating resin to obtain a sodium carbonate pure solution;

(4) Carrying out acid-base neutralization reaction, solid-liquid separation and pure water rinsing on the sodium carbonate pure solution obtained in the step (3) and hydrogen fluoride to obtain sodium fluoride wet product solid and mother liquor;

(5) Removing impurities from the mother liquor obtained in the step (4) by nanofiltration to obtain a purified mother liquor which is used as a sodium fluoride solution for preparing a sodium carbonate solution in the operation step (1);

(6) And (3) drying the wet sodium fluoride product solid obtained in the step (4) to obtain the electronic grade high-purity sodium fluoride.

2. The method for producing electronic grade sodium fluoride according to claim 1, wherein in the step (1), the sodium carbonate is common industrial grade sodium carbonate, and the sodium carbonate content is not less than 99.0%.

3. The method for producing electronic grade high purity sodium fluoride according to claim 1, wherein in step (1), the sodium fluoride solution has a sodium fluoride mass content of 0 to 5.0%.

4. The method for producing electronic grade sodium fluoride according to claim 1, wherein in the step (1), the filter membrane is a microporous filter membrane having a pore size of 0.05 to 2.0 μm.

5. The method for producing electronic grade high purity sodium fluoride according to claim 1, wherein in step (1), the sodium carbonate crude solution has a sodium carbonate mass concentration of 1.0 to 32.0%.

6. The method for producing electronic grade sodium fluoride according to claim 1, wherein in the step (1), the operation temperature is 0 to 100 ℃.

7. The method for producing electronic grade sodium fluoride according to claim 1, wherein in the step (2), the activated carbon is powdery activated carbon with a particle size of 100-1000 meshes, and the amount of the activated carbon is 0.01-20.0% of the weight of sodium carbonate contained in the crude solution of sodium carbonate.

8. The method for producing electronic grade sodium fluoride according to claim 1, wherein in the step (2), the filter membrane is a microporous filter membrane having a pore size of 0.05 to 2.0 μm.

9. The method for producing electronic grade sodium fluoride according to claim 1, wherein in the step (2), the operation temperature is 0 to 100 ℃.

10. The method for producing electronic grade high purity sodium fluoride according to claim 1, wherein in step (3), the chelate resin is one or both of an aminocarboxylic acid type chelate resin and an aminophosphoric acid type chelate resin.

11. The method for producing electronic grade sodium fluoride according to claim 1, wherein in the step (3), the operation temperature is 0 to 80 ℃.

12. The method for producing electronic grade high purity sodium fluoride according to claim 1, wherein in step (4), the hydrogen fluoride is selected from one or more of the following: hydrogen fluoride gas, anhydrous hydrogen fluoride liquid, and aqueous hydrogen fluoride solution.

13. The method according to claim 1 or 12, wherein in the step (4), the concentration of hydrogen fluoride in the aqueous hydrogen fluoride solution is 1.0 to 50.0% by mass.

14. The method for producing electronic grade sodium fluoride according to claim 1, wherein in the step (4), the reaction temperature is 0 to 100 ℃.

15. The method for producing electronic grade sodium fluoride according to claim 1, wherein in the step (5), the operation temperature is 0 to 80 ℃.

16. The method for producing electronic grade sodium fluoride according to claim 1, wherein in the step (6), the drying temperature is in the range of 0 to 200 ℃.