Synthesis process of solid inorganic salt compound

Abstract

The invention discloses a synthesis process of a solid inorganic salt compound, and belongs to the technical field of inorganic salt synthesis, the key point of the technical scheme is that the synthesis process comprises the following synthesis steps: S1, adding alkali into water, dissolving until clarification, and filtering to obtain an alkali solution with the concentration of 47-53 wt%; s2, acid is added into water to be diluted and then filtered, and an acid solution with the concentration being 63-70 wt% is obtained; s3, under stirring, adding an alkali solution into the acid solution in batches, controlling the mixing reaction temperature not to exceed 80 DEG C, after the alkali solution is completely added and the pH of the mixture is detected to meet the requirement, stirring, cooling, crystallizing, filtering, washing and drying to obtain a solid inorganic salt compound, and after the acid solution and the alkali solution are mixed and react by adjusting the total water consumption of a reaction system, obtaining the solid inorganic salt compound. The solution system belongs to a supersaturated solution of a final product, so that the inorganic salt is directly separated out by cooling without concentration adjustment, the yield of the obtained inorganic salt is more than 80%, and the energy consumption is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of inorganic salt synthesis, and in particular to a synthesis process of solid inorganic salt compounds. Background Art

[0002] Solid inorganic salts are salt substances composed of inorganic elements, usually in solid form. Most of them are products generated by the reaction of acid and base in aqueous solution. They are widely used in industry, agriculture, food and medicine. For example, sodium acetate can be used as a preservative, acidity regulator and buffer in the food industry, used in the preparation of dialysis fluid in the pharmaceutical industry, and used as a raw material for organic synthesis in the chemical industry to prepare acetic anhydride. Disodium hydrogen phosphate is used as a food additive to adjust pH value in the food industry, used in the preparation of buffer solutions in the pharmaceutical industry, and used in the preparation of detergents and dyes in the chemical industry. Trisodium phosphate is used in industrial cleaning and household cleaners to remove oil and hard scale, as a food additive in the food industry, and as a water softener and corrosion inhibitor in water treatment. Potassium dihydrogen phosphate is used in agriculture as a high-efficiency phosphorus-potassium compound fertilizer, in the pharmaceutical industry for the preparation of buffer solutions and nutritional supplements, and in the chemical industry for the preparation of special glass, ceramics, and flame retardant materials. Potassium sulfate is used in agriculture as a chlorine-free potassium fertilizer to promote crop growth, in the chemical industry for the preparation of potassium salts, potash, and special glass, and in the pharmaceutical industry as a pharmaceutical excipient for the preparation of laxatives and electrolyte supplements.

[0003] After the synthesis reaction is completed, existing compounds such as sodium acetate, disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate and potassium sulfate need to be concentrated by vacuum distillation and then cooled for crystallization to improve the purity and yield of the product. However, this process has high energy consumption. Summary of the Invention

[0004] In order to solve the problems in the prior art, the present application provides a synthesis process for solid inorganic salt compounds. The present application adjusts the total water consumption of the reaction system so that after the acid solution and the alkaline solution are mixed and reacted, the solution system becomes a supersaturated solution of the final product, thereby eliminating the need for concentration adjustment and directly precipitating the inorganic salt by cooling. The obtained inorganic salt yield is above 80%, thereby reducing energy consumption.

[0005] The present application provides a synthesis process for a solid inorganic salt compound using the following technical solution: A synthesis process for a solid inorganic salt compound comprises the following synthesis steps: S1. Add alkali into water, dissolve it and filter it to obtain an alkali solution with a concentration of 47-53 wt%; S2, adding the acid to water, diluting it, and filtering it to obtain an acid solution with a concentration of 63-70 wt%; S3. Under stirring, add the alkaline solution to the acid solution in batches, control the mixed reaction temperature not to exceed 80°C, after the alkaline solution is added, detect the mixture pH to meet the requirements, stir, cool and crystallize, filter, wash and dry to obtain a solid inorganic salt compound.

[0006] By adopting the above technical solution, the acid and alkali raw materials used to prepare solid inorganic salts are first configured into a solution. By controlling the amount of water used, after the acid solution and the alkali solution are mixed and reacted, the solution system is a supersaturated solution of the final product, so there is no need to concentrate and adjust the concentration. The inorganic salt is directly precipitated by stirring and cooling. The yield of the obtained inorganic salt is above 70%, which reduces energy consumption. In addition, the present application filters the acid solution and the alkali solution before mixing to remove insoluble impurities that may exist in the raw materials. At the same time, when the temperature during the mixing reaction is controlled not to exceed 80°C, the volatilization of the acid solution is reduced and the probability of side reactions is effectively reduced, so that the purity of the inorganic salt finally obtained can reach the effect of analytical purity. Moreover, since the synthesized inorganic salt does not require the operation step of vacuum distillation, the cost is effectively reduced.

[0007] In a preferred embodiment, the solid inorganic salt compound is one of sodium acetate, disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate, and potassium sulfate.

[0008] In a preferred embodiment, the mixing reaction temperature in the synthesis of sodium acetate is 50-60°C.

[0009] In a preferred embodiment, the mixing reaction temperature in the synthesis of disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate and potassium sulfate is 65-75°C.

[0010] By adopting the above technical solution, the mixed reaction temperature in the synthesis of sodium acetate is controlled at 50-60°C, and the mixed reaction temperature in the synthesis of disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate, and potassium sulfate is controlled at 65-75°C, which can effectively reduce the probability of side reactions occurring during the synthesis of each inorganic salt, while also ensuring the efficiency of the acid-base reaction.

[0011] In a preferred embodiment, in step S3, the temperature is lowered to 20-25° C. and then kept stirred for 12 hours.

[0012] In a preferred embodiment, the cooling rate is 0.5-1.0°C / min.

[0013] By adopting the above technical solution, when the cooling rate is controlled at 0.5-1.0°C / min, it is beneficial for the inorganic salt to form large and uniform crystals during the precipitation process, and avoid the inorganic salt crystals from wrapping unreacted raw materials during rapid precipitation, which leads to a decrease in the purity of the inorganic salt. Furthermore, when the cooling rate is controlled within the range of 0.5-1°C / min, the crystal purity and production efficiency can also be balanced.

[0014] In a preferred embodiment, the stirring rates during the mixing and stirring, cooling and stirring, and heat preservation and stirring are all 200-400 rpm.

[0015] By adopting the above technical solution, when the stirring rate is between 200-400 rpm, the acid and the base can be evenly mixed, avoiding the occurrence of side reactions caused by local overheating. At the same time, during the cooling and stirring process, the solution can be ensured to be evenly cooled, avoiding local overcooling, and the crystals can be uniformly precipitated, thereby reducing impurities in the crystals. During the heat preservation and stirring process, the uniform growth of the crystals can be promoted, agglomeration can be prevented, and the yield of the inorganic salt can be improved.

[0016] In a preferred embodiment, a stainless steel filter is used in step S1, and the filter pore size is 0.45 μm.

[0017] In a preferred embodiment, in step S2, an acid- and alkali-resistant PP folded microporous filter element is used, and the filter pore size is 0.45 μm.

[0018] In summary, this application has the following beneficial effects: 1. The present application adjusts the total water consumption of the reaction system so that after the acid solution and the alkaline solution are mixed and reacted, the solution system is a supersaturated solution of the final product, thereby eliminating the need for concentration adjustment and directly allowing the inorganic salt to precipitate by stirring and cooling, thereby reducing energy consumption.

[0019] 2. After omitting the reduced pressure distillation step, the preparation method of the present application improves the purity and yield of the product by filtering the raw material liquid of the reaction, controlling the reaction temperature, cooling rate and stirring rate. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below with reference to the examples. All reagents without manufacturer indicated are conventional reagents that can be purchased commercially.

[0021] In a preferred embodiment, the synthesis process of the solid inorganic salt compound comprises the following synthesis steps: S1. Add alkali into water, dissolve it and filter it to obtain an alkali solution with a concentration of 47-53 wt%; S2, adding the acid to water, diluting it, and filtering it to obtain an acid solution with a concentration of 63-70 wt%; S3. Under stirring, add the alkaline solution to the acid solution in batches, control the mixed reaction temperature not to exceed 80°C, after the alkaline solution is added, detect the mixture pH to meet the requirements, stir, cool and crystallize, filter, wash and dry to obtain a solid inorganic salt compound.

[0022] In a preferred embodiment, the solid inorganic salt compound is one of sodium acetate, disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate, and potassium sulfate, wherein sodium acetate is synthesized by reacting sodium hydroxide and acetic acid, disodium hydrogen phosphate is synthesized by reacting sodium hydroxide and phosphoric acid, trisodium phosphate is synthesized by reacting sodium hydroxide and phosphoric acid, potassium dihydrogen phosphate is synthesized by reacting potassium hydroxide and phosphoric acid, and potassium sulfate is synthesized by reacting potassium hydroxide and sulfuric acid.

[0023] In a preferred embodiment, the mixing reaction temperature in the synthesis of sodium acetate is 50-60°C.

[0024] In a preferred embodiment, the mixing reaction temperature in the synthesis of disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate and potassium sulfate is 65-75°C.

[0025] In a preferred embodiment, in step S3, the temperature is lowered to 20-25° C. and then kept stirred for 12 hours.

[0026] In a preferred embodiment, the cooling rate is 0.5-1.0°C / min.

[0027] In a preferred embodiment, the stirring rates during the mixing and stirring, cooling and stirring, and heat preservation and stirring are all 200-400 rpm.

[0028] In a preferred embodiment, a stainless steel filter is used in step S1, and the filter pore size is 0.45 μm.

[0029] In a preferred embodiment, in step S2, an acid- and alkali-resistant PP folded microporous filter element is used, and the filter pore size is 0.45 μm.

[0030] Example 1.1 A synthesis process for sodium acetate comprises the following synthesis steps: S1, 9 kg of sodium hydroxide was added to 9 kg of water, dissolved and filtered using a stainless steel filter with a pore size of 0.45 μm to obtain an alkaline solution with a concentration of 50 wt%, and the alkaline solution was transferred to a crystallization tank for stirring; S2, adding 14 kg of glacial acetic acid to 7 kg of water for dilution, and filtering through an acid- and alkali-resistant PP folded microporous filter element with a pore size of 0.45 μm to obtain an acid solution with a concentration of 66.7 wt%; S3. Add the alkaline solution to the acid solution in batches at a stirring rate of 300 rpm, and cool the mixture by circulating water in the jacket of the crystallizer to control the mixed reaction temperature to 55±2°C. Within this temperature range, add the alkaline solution in batches. After the alkaline solution is added and stirred evenly, the pH of the mixture is detected to be 8.5 and the density is 1.2 g / cm 3 The mixture was cooled to 25°C at a stirring rate of 300 rpm and a cooling rate of 1.0°C / min, then kept warm and stirred for 12 h at a stirring rate of 300 rpm. The mixture was filtered, washed, and dried at 70°C to obtain a solid inorganic salt compound.

[0031] Example 1.2 A synthesis process for sodium acetate comprises the following synthesis steps: S1, 8kg of sodium hydroxide was added to 9kg of water, dissolved and filtered through a stainless steel filter with a pore size of 0.45 μm to obtain an alkaline solution with a concentration of 47wt%, and the alkaline solution was transferred to a crystallization tank for stirring; S2, adding 14 kg of glacial acetic acid to 7 kg of water for dilution, and filtering through an acid- and alkali-resistant PP folded microporous filter element with a pore size of 0.45 μm to obtain an acid solution with a concentration of 66.7 wt%; S3. Under the condition of stirring rate of 200 rpm, add alkali solution to the acid solution in batches, and cool it by circulating water in the jacket of crystallizer to control the mixed reaction temperature at 55±2°C. Within this temperature range, add the alkali solution in batches. After the alkali solution is added and stirred evenly, the pH of the mixture is detected to be 9.0 and the density is 1.2 g / cm 3 The mixture was cooled to 20°C at a stirring rate of 200 rpm and a cooling rate of 1.0°C / min, then kept warm and stirred for 12 h at a stirring rate of 200 rpm. The mixture was filtered, washed, and dried at 90°C to obtain a solid inorganic salt compound.

[0032] Example 1.3 A synthesis process for sodium acetate comprises the following synthesis steps: S1, 9kg of sodium hydroxide was added to 8kg of water, dissolved and filtered using a stainless steel filter with a pore size of 0.45μm to obtain an alkaline solution with a concentration of 53wt%, and the alkaline solution was transferred to a crystallization tank for stirring; S2, adding 15 kg of glacial acetic acid to 8 kg of water for dilution, and filtering through an acid- and alkali-resistant PP folded microporous filter element with a pore size of 0.45 μm to obtain an acid solution with a concentration of 65.2 wt%; S3. Add the alkaline solution to the acid solution in batches at a stirring rate of 400 rpm, and cool the mixture by circulating water in the jacket of the crystallizer to control the mixed reaction temperature at 55±2°C. Within this temperature range, add the alkaline solution in batches. After the alkaline solution is added and stirred evenly, the pH of the mixture is detected to be 9.5 and the density is 1.3 g / cm 3 The mixture was cooled to 20°C at a stirring rate of 400 rpm and a cooling rate of 1.0°C / min, kept warm and stirred for 12 h at a stirring rate of 400 rpm, filtered, washed, and dried at 90°C to obtain a solid inorganic salt compound.

[0033] Example 2.1 A synthesis process for disodium hydrogen phosphate comprises the following synthesis steps: S1, 13kg of sodium hydroxide was added to 13kg of water, and then the solution was filtered through a stainless steel filter with a pore size of 0.45μm to obtain an alkaline solution with a concentration of 50wt%, and the alkaline solution was transferred to a crystallization tank for stirring; S2. Add 16 kg of phosphoric acid to 8 kg of water for dilution, and filter through an acid- and alkali-resistant PP folded microporous filter element with a pore size of 0.45 μm to obtain an acid solution with a concentration of 66.7 wt %; S3. Add the alkaline solution to the acid solution in batches at a stirring rate of 300 rpm, and cool the mixture by circulating water in the jacket of the crystallizer to control the mixed reaction temperature at 70±2°C. In this temperature range, add the alkaline solution in batches. After the alkaline solution is added and stirred evenly, the pH of the mixture is detected to be 8.5 and the density is 1.3 g / cm 3 The mixture was cooled to 20°C at a stirring rate of 300 rpm and a cooling rate of 1.0°C / min, then kept warm and stirred for 12 h at a stirring rate of 300 rpm. The mixture was filtered, washed, and dried at 90°C to obtain a solid inorganic salt compound.

[0034] Example 3.1 A synthesis process for trisodium phosphate comprises the following synthesis steps: S1. Add 17 kg of sodium hydroxide to 17 kg of water, dissolve it, and filter it through a stainless steel filter with a pore size of 0.45 μm to obtain an alkaline solution with a concentration of 50 wt%, and transfer the alkaline solution to a crystallization tank for stirring; S2. Add 15 kg of phosphoric acid to 7 kg of water for dilution, and filter through an acid- and alkali-resistant PP folded microporous filter element with a pore size of 0.45 μm to obtain an acid solution with a concentration of 68.2 wt %; S3. Add the alkaline solution to the acid solution in batches at a stirring rate of 300 rpm, and cool the mixture by circulating water in the jacket of the crystallizer to control the mixed reaction temperature at 70±2°C. In this temperature range, add the alkaline solution in batches. After the alkaline solution is added and stirred evenly, the pH of the mixture is detected to be 12 and the density is 1.3 g / cm 3 The mixture was cooled to 25°C at a stirring rate of 300 rpm and a cooling rate of 1.0°C / min, then kept warm and stirred for 12 h at a stirring rate of 300 rpm. The mixture was filtered, washed, and dried at 90°C to obtain a solid inorganic salt compound.

[0035] Example 4.1 A synthesis process for potassium dihydrogen phosphate comprises the following synthesis steps: S1. Add 10 kg of potassium hydroxide to 10 kg of water, dissolve it, and filter it through a stainless steel filter with a pore size of 0.45 μm to obtain an alkaline solution with a concentration of 50 wt%, and transfer the alkaline solution into a crystallization tank for stirring; S2. Add 18 kg of phosphoric acid to 9 kg of water for dilution, and filter through an acid- and alkali-resistant PP folded microporous filter element with a pore size of 0.45 μm to obtain an acid solution with a concentration of 66.7 wt %; S3. Under the condition of stirring rate of 300 rpm, add alkali solution to the acid solution in batches, and cool it by circulating water in the jacket of crystallizer to control the mixed reaction temperature between 70±2°C. In this temperature range, add the alkali solution in batches. After the alkali solution is added and stirred evenly, the pH of the mixture is detected to be 5.0 and the density is 1.8 g / cm 3 The mixture was cooled to 25°C at a stirring rate of 300 rpm and a cooling rate of 1.0°C / min, then kept warm and stirred for 12 h at a stirring rate of 300 rpm. The mixture was filtered, washed, and dried at 90°C to obtain a solid inorganic salt compound.

[0036] Example 5.1 A synthesis process for potassium dihydrogen phosphate comprises the following synthesis steps: S1, 15kg of potassium hydroxide was added to 15kg of water, and then filtered through a stainless steel filter with a pore size of 0.45μm to obtain an alkaline solution with a concentration of 50wt%, and the alkaline solution was transferred to a crystallization tank for stirring; S2. Add 13 kg of phosphoric acid to 6 kg of water for dilution, and filter through an acid- and alkali-resistant PP folded microporous filter element with a pore size of 0.45 μm to obtain an acid solution with a concentration of 68.4 wt %; S3. Add the alkaline solution to the acid solution in batches at a stirring rate of 300 rpm, and cool the mixture by circulating water in the jacket of the crystallizer to control the mixed reaction temperature between 70±2°C. Within this temperature range, add the alkaline solution in batches. After the alkaline solution is added and stirred evenly, the pH of the mixture is detected to be 4.0 and the density is 1.7 g / cm 3 The mixture was cooled to 20-25°C at a stirring rate of 300 rpm and a cooling rate of 1.0°C / min, then kept warm and stirred for 12 hours at a stirring rate of 300 rpm. The mixture was filtered, washed, and dried at 90°C to obtain an analytically pure solid inorganic salt compound.

[0037] Comparative Example 1.1 A synthesis process of sodium acetate, which differs from Example 1.1 in that the reaction temperature in step S3 is 90±2°C, and the rest are the same as Example 1.1.

[0038] Comparative Example 1.2 A synthesis process for sodium acetate, which differs from Example 1.1 in that 6 kg of sodium hydroxide is added to 9 kg of water to prepare a 40 wt % alkaline solution, and 8.56 kg of glacial acetic acid is added to 7 kg of water to prepare a 55 wt % acid solution. The other preparation steps are the same as those in Example 1.1.

[0039] Comparative Example 1.3 A synthesis process for sodium acetate, which differs from Example 1.1 in that 13.5 kg of sodium hydroxide is added to 9 kg of water to prepare a 60 wt% alkaline solution, and 21 kg of glacial acetic acid is added to 7 kg of water to prepare a 75% acid solution. The other preparation steps are the same as those in Example 1.1.

[0040] Performance testing The solid inorganic salt compounds obtained in the above embodiments and comparative examples were tested for purity and yield, and the test results are shown in Table 1; and the quality standards of each product are as follows: GB / T693-2024 "Chemical Reagent Sodium Acetate", GB / T1263-2006 "Chemical Reagent Disodium Hydrogen Phosphate Dodecahydrate (Disodium Hydrogen Phosphate)", HG / T2517-2009 "Industrial Trisodium Phosphate", GB / T1274-2011 "Chemical Reagent Potassium Dihydrogen Phosphate", GB / T16496-1996 "Chemical Reagent Potassium Sulfate".

[0041] Table 1 Yield and purity test results of each solid inorganic salt project Example 1.1 Example 1.2 Example 1.3 Example 2.1 Example 3.1 purity / % 99.721 99.854 99.863 99.892 99.903 Yield / % 90.26 86.78 85.47 89.68 88.76 project Example 4.1 Example 5.1 Comparative Example 1.1 Comparative Example 1.2 Comparative Example 1.3 purity / % 99.924 99.887 92.835 91.752 92.671 Yield / % 86.21 87.57 81.54 80.67 82.45 As can be seen from Table 1, the purity of the solid inorganic salt compounds obtained by the preparation method of the present application is above 99.7%, meeting the requirements of analytical purity. In addition, the yield of the solid inorganic salt compounds obtained in the examples of the present application is above 85%, and no vacuum distillation is required in the entire preparation process, which reduces energy consumption and improves production efficiency.

[0042] Comparative Example 1.1 Compared with Example 1.1, when the acid-base mixed reaction temperature is 90°C, the purity and yield of sodium acetate obtained in Comparative Example 1.1 are both reduced. The reason is that when the reaction temperature is too high, glacial acetic acid will volatilize and a small amount of decomposition of the product sodium acetate will occur. As a result, during the crystallization process, the crystals will be coated with impurities, resulting in a decrease in the purity of the solid sodium acetate finally obtained. In addition, due to the loss of raw materials, the yield of solid sodium acetate is also reduced.

[0043] Comparative Examples 1.2-1.3 Compared with Example 1.1, when the concentration of the alkali and acid solutions is low (i.e., too much water), the purity and yield of the solid sodium acetate obtained in Comparative Example 1.2 are significantly reduced. The reason is that the water content is too high, which slows down the crystallization rate and makes it easier for the unreacted acid and alkali to be wrapped in the crystals, thereby reducing the purity. Moreover, when there is too much water in the reaction system, the solubility of sodium acetate is increased, resulting in more salts remaining in the mother liquor during cooling and crystallization, resulting in a decrease in yield. When the concentration of the acid or alkali solution is too high (i.e., too little water), the purity and yield of the solid sodium acetate obtained in Comparative Example 1.3 are significantly reduced. The reason is that excessively high concentrations of acid and alkali may cause local intense heat release and produce by-products. In addition, the supersaturation of the solution under low water volume is extremely high, and the crystal precipitation speed is too fast, which easily forms small or irregular crystals and absorbs more impurities in the mother liquor, thereby reducing the purity of solid sodium acetate. In addition, due to the high concentration of acid and alkali solutions, the viscosity of the solution increases significantly, the reactants are unevenly mixed, and the mass of the substances actually participating in the reaction is reduced, so the content of the solid sodium acetate finally generated is significantly reduced. Therefore, the concentration of the acid and alkali solutions should be reasonably controlled to effectively improve the purity and yield of the solid inorganic salt compound.

[0044] The embodiments of this specific implementation method are all preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A process for synthesizing a solid inorganic salt compound, characterized in that: The synthesis steps include: S1, adding alkali to water, dissolving it and filtering it to obtain an alkaline solution with a concentration of 47-53wt%; S2, adding the acid to water, diluting it, and filtering to obtain an acid solution with a concentration of 63-70 wt%; S3. Under stirring, add the alkaline solution to the acid solution in batches, control the mixed reaction temperature not to exceed 80°C, after the alkaline solution is added, detect the mixture pH to meet the requirements, stir, cool and crystallize, filter, wash and dry to obtain a solid inorganic salt compound.

2. The synthesis process of a solid inorganic salt compound according to claim 1, characterized in that: The solid inorganic salt compound is one of sodium acetate, disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate, and potassium sulfate.

3. The synthesis process of a solid inorganic salt compound according to claim 2, characterized in that: The mixing reaction temperature in the synthesis of sodium acetate is 50-60°C.

4. The synthesis process of a solid inorganic salt compound according to claim 2, characterized in that: The mixing reaction temperature in the synthesis of disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate and potassium sulfate is 65-75°C.

5. The synthesis process of a solid inorganic salt compound according to claim 1, characterized in that: In step S3, the temperature was lowered to 20-25° C. and then kept warm and stirred for 12 h.

6. The synthesis process of a solid inorganic salt compound according to claim 5, characterized in that: The cooling rate is 0.5-1.0°C / min.

7. The synthesis process of a solid inorganic salt compound according to claim 5, characterized in that: The stirring rates during the mixing, cooling and heat-insulating stirring are all 200-400 rpm.

8. The process for synthesizing a solid inorganic salt compound according to claim 1, wherein: In step S1, a stainless steel filter is used, and the filter pore size is 0.45 μm.

9. The synthesis process of a solid inorganic salt compound according to claim 1, characterized in that: In step S2, an acid- and alkali-resistant PP folded microporous filter element is used, and the filter pore size is 0.45 μm.