Production method of high-purity electronic-grade hydrochloric acid

Abstract

The invention relates to the technical field of production of chemical products, and particularly discloses a production method of high-purity electronic-grade hydrochloric acid. The raw materials used in the method are wide in source, industrial chemicals such as industrial hydrochloric acid and industrial sodium chloride and waste silicon tetrachloride are contained, the treatment steps are relatively simple, the defects in related technologies are overcome, the production cost of the electronic-grade hydrochloric acid is reduced, and the production efficiency of the electronic-grade hydrochloric acid is improved.

Description

Technical Field

[0001] The present application relates to the technical field of chemical product production, and more specifically, to a method for producing high-purity electronic-grade hydrochloric acid. Background Art

[0002] In high-tech fields such as semiconductors and integrated circuits, wet electronic chemicals have garnered widespread attention due to their critical role in processes such as cleaning and etching. As a crucial component of these wet electronic chemicals, the purity of hydrochloric acid directly impacts the stability of the production process and the quality of the final product. However, hydrochloric acid is susceptible to contamination during production and transportation, which can interfere with chemical reactions and potentially damage equipment. Therefore, research into ultrapurification processes and impurity control methods for hydrochloric acid is crucial for improving the quality of wet electronic chemicals.

[0003] Ultrapurification of hydrochloric acid is essential to meet the stringent purity requirements of chemical reagents in high-tech manufacturing. Advanced purification processes, such as multi-stage distillation, nanofiltration, and reverse osmosis, effectively remove numerous impurities from hydrochloric acid, significantly improving its purity. Specifically, multi-stage distillation separates volatile impurities at high temperatures, while nanofiltration and reverse osmosis remove particulate and soluble impurities through precise physical screening.

[0004] Regarding the above-mentioned related technologies, the inventors believe that although the multi-stage distillation, nanofiltration and reverse osmosis processes in the related technologies can achieve the preparation of electronic-grade hydrochloric acid, these processes have high requirements on the purity of the raw materials. Using general industrial-grade hydrochloric acid as raw material requires complex processing steps to meet the product standards of electronic-grade hydrochloric acid, which limits the output of electronic-grade hydrochloric acid. Summary of the Invention

[0005] The methods in the related art have high requirements for raw materials. Using general industrial-grade hydrochloric acid as raw material requires complex processing steps to meet the product standards of electronic-grade hydrochloric acid, which limits the output of electronic-grade hydrochloric acid. To improve this defect, the present application provides a method for producing high-purity electronic-grade hydrochloric acid.

[0006] The present application provides a method for producing high-purity electronic-grade hydrochloric acid, which adopts the following technical solution: A method for producing high-purity electronic-grade hydrochloric acid comprises the following steps: (1) Under nitrogen protection, silicon tetrachloride is added to a hydrochloric acid mother liquor having a concentration of 24-27 wt%, and the mixture is cooled while stirring the reaction. After the reaction is completed, the product is input into a desorption tower and desorbed under negative pressure. A mixture of hydrogen chloride and water vapor is collected from the top of the tower; in this step, the hydrochloric acid mother liquor comprises industrial-grade hydrochloric acid; (2) passing the mixed gas obtained in step (1) into a saturated sodium chloride solution for washing, using a carbon dioxide adsorbent to adsorb the discharged gas, and adding water to absorb the tail gas to obtain high-purity dilute hydrochloric acid; in this step, the saturated sodium chloride solution contains undissolved sodium chloride solids; (3) using sodium chloride solution as cathode liquid and anolyte, a hydrogen evolution electrode as cathode, a platinum electrode as anode, and a sodium ion exchange membrane as a diaphragm, obtaining hydrogen and chlorine after electrolysis, mixing the hydrogen and chlorine in a synthesis furnace and then igniting them, passing the obtained gas into a saturated sodium chloride solution for washing, and then absorbing it with the high-purity dilute hydrochloric acid obtained in step (2) to obtain high-purity electronic grade hydrochloric acid.

[0007] By adopting the above technical solution, the method of the present application uses silicon tetrachloride, a by-product associated with the polysilicon production process, to react with hydrochloric acid mother liquor. After the silicon tetrachloride reacts with water, hydrogen chloride and silicon dioxide precipitate are produced, which increases the concentration of the hydrochloric acid mother liquor. Subsequently, a mixed gas of hydrogen chloride and water vapor is precipitated under the negative pressure condition of the analytical tower. After the mixed gas is washed with a saturated sodium chloride solution, the water vapor is intercepted in the sodium chloride solution. The undissolved sodium chloride solid can always keep the sodium chloride solution in a saturated state to prevent the dissolution loss of hydrogen chloride. Thereafter, after absorption by a carbon dioxide absorbent, a relatively pure hydrogen chloride tail gas can be obtained. After adding water for absorption, high-purity dilute hydrochloric acid can be obtained. In step (3), the present application electrolyzes the sodium chloride solution. The hydrogen chloride solution at this stage can be obtained directly by diluting the saturated sodium chloride solution of step (2), or it can be prepared separately using industrial-grade sodium chloride. The hydrogen and chlorine produced by electrolysis react in the furnace to generate hydrogen chloride gas. During this process, chlorine reacts with the steel furnace wall, resulting in the entrainment of ferric chloride vapor in the hydrogen chloride. After the tail gas is absorbed by a saturated sodium chloride solution, the ferric chloride is cooled and separated from the hydrogen chloride, thereby obtaining a relatively pure hydrogen chloride gas. After this part of the hydrogen chloride gas is absorbed by the high-purity dilute hydrochloric acid obtained in step (2), electronic-grade hydrochloric acid can be obtained. The method of the present application uses a wide range of raw materials, including not only industrial-grade chemicals such as industrial-grade hydrochloric acid and industrial-grade sodium chloride, but also waste silicon tetrachloride. The processing steps are relatively simple, overcome the defects in the related art, reduce the production cost of electronic-grade hydrochloric acid, and improve the production efficiency of electronic-grade hydrochloric acid.

[0008] Preferably, the hydrochloric acid mother liquor also includes a regeneration mother liquor, which is obtained by filtering the acid solution remaining at the bottom of the analytical tower and diluting it with water.

[0009] By adopting the above technical solution, the remaining acid liquid at the bottom of the decomposition tower is concentrated hydrochloric acid mixed with silica. After filtration to remove silica and dilution with water, the resulting regenerated mother liquor can be used as a substitute for industrial-grade hydrochloric acid, thereby achieving full utilization of hydrochloric acid and also obtaining economically valuable by-product silica.

[0010] Preferably, the carbon dioxide adsorbent is prepared according to the following method: (1) natural clay is added to hydrochloric acid for heat treatment, then cooled, filtered and washed, and dried to obtain acidified soil; (2) adding the acidified soil to a sodium hydroxide solution, and then adding a sodium aluminate solution and stirring and mixing to obtain a raw material liquid, adding the raw material liquid to a reactor for hydrothermal crystallization, and then cooling and filtering, washing and drying the filter residue to obtain a carbon dioxide adsorbent.

[0011] By adopting the above technical solution, this application is based on natural clay, adjusts the silicon-aluminum ratio through sodium aluminate, and uses a hydrothermal method to prepare a carbon dioxide adsorbent with a zeolite structure, which helps to fully remove carbon dioxide impurities in hydrogen chloride gas.

[0012] Preferably, the natural clay is attapulgite.

[0013] By adopting the above technical solution, the cost of attapulgite is low, which can reduce the preparation cost of the carbon dioxide adsorbent.

[0014] Preferably, the silicon to aluminum molar ratio of the carbon dioxide adsorbent is 1.58-1.64.

[0015] By adopting the above technical solution, within the above silicon-aluminum molar ratio range, the structure of the carbon dioxide adsorbent is closer to 13X zeolite molecular sieve, which has a better removal effect on carbon dioxide gas and helps to reduce the replacement frequency of the carbon dioxide adsorbent.

[0016] Preferably, in the method for preparing the carbon dioxide adsorbent, alkali-melted modified fly ash and acidified soil are added together into a sodium hydroxide solution, and the alkali-melted modified fly ash is prepared according to the following method: The sludge incineration fly ash is mixed with sodium hydroxide, the mixture is heated to melt, then cooled, and then ground to obtain alkali-fused modified fly ash.

[0017] By adopting the above-mentioned technical solution, this application uses sodium hydroxide to alkali-melt-modify sludge incineration fly ash, resulting in alkali-melt-modified fly ash. After hydrothermal crystallization, the alkali-melt-modified fly ash can form a large porous structure, increasing the specific surface area of ​​the carbon dioxide adsorbent, enabling more effective removal of carbon dioxide gas mixed with hydrogen chloride, and helping to reduce the frequency of carbon dioxide adsorbent replacement.

[0018] Preferably, the weight of the alkali-melted modified fly ash is 20-25% of the total weight of the natural clay.

[0019] By adopting the above technical solution, the present application optimizes the amount of alkali-melted modified fly ash, which helps to increase the specific surface area of ​​the carbon dioxide adsorbent, thereby reducing the replacement frequency of the carbon dioxide adsorbent.

[0020] Preferably, the carbon dioxide adsorbent is adsorbed at 30-40°C.

[0021] By adopting the above technical solution, the present application optimizes the temperature conditions for the adsorption of carbon dioxide adsorbent, which can more effectively remove the carbon dioxide gas mixed in hydrogen chloride and help reduce the replacement frequency of the carbon dioxide adsorbent.

[0022] Preferably, in step (3), the obtained hydrogen and chlorine are mixed in a molar ratio of (1.05-1.10):1.

[0023] By adopting the above technical solution, the present application makes the hydrogen slightly excessive to ensure sufficient reaction of the chlorine. Since hydrogen is poorly soluble in water, the hydrogen obtained in step (3) can be separated separately after being absorbed by high-purity dilute hydrochloric acid, and can be collected and reused in the production of hydrogen chloride.

[0024] Preferably, the vacuum degree during the analysis process of the analysis tower is -(0.05-0.10) MPa.

[0025] By adopting the above technical solution, the present application optimizes the vacuum degree during the operation of the analytical tower, which helps to fully realize the precipitation of hydrogen chloride and water vapor.

[0026] In summary, this application has the following beneficial effects: 1. The raw materials used in the method of the present application are from a wide range of sources, including not only industrial-grade chemicals such as industrial-grade hydrochloric acid and industrial-grade sodium chloride, but also waste silicon tetrachloride. The processing steps are relatively simple, which overcomes the defects in the relevant technologies, reduces the production cost of electronic-grade hydrochloric acid, and improves the production efficiency of electronic-grade hydrochloric acid.

[0027] 2. This application uses sodium hydroxide to alkali-melt-modify sludge incineration fly ash, producing alkali-melt-modified fly ash. After hydrothermal crystallization, the alkali-melt-modified fly ash forms a porous structure, increasing the specific surface area of ​​the carbon dioxide adsorbent. This allows for more effective removal of carbon dioxide gas from hydrogen chloride, contributing to improved quality of electronic-grade hydrochloric acid. DETAILED DESCRIPTION

[0028] The present application is further described in detail below with reference to the Examples, Preparation Examples and Comparative Examples. The raw materials involved in the present application can all be obtained commercially.

[0029] Preparation example of carbon dioxide adsorbent The following is an explanation using Preparation Example 1.

[0030] Preparation Example 1 In this preparation example, attapulgite is used as natural clay, and the weight percentage composition of the oxides of attapulgite is as follows: 56.2% silicon dioxide, 11.1% aluminum oxide, 0.11% sodium oxide, 8.1% magnesium oxide, 8.5% hematite, 5.3% calcium oxide, 1.5% potassium oxide, 1.3% titanium dioxide, 0.3% manganese dioxide, and the remainder is impurities that do not affect the performance.

[0031] In this preparation example, the carbon dioxide adsorbent was prepared according to the following method: (1) Natural clay was added to 3 mol / L hydrochloric acid at a solid-liquid ratio of 1:4, and heat-treated at 80°C for 48 h, followed by cooling, filtration, washing, and drying at 100°C to obtain acidified soil; (2) The acidified soil was added to a 2.6 mol / L sodium hydroxide solution at a weight ratio of 1:5, and then a sodium aluminate solution was added and stirred to obtain a raw material liquid. The raw material liquid was added to a reactor and hydrothermally crystallized at 90°C for 24 hours, and then cooled and filtered. The filter residue was washed with water and dried to obtain a carbon dioxide adsorbent with a silicon-aluminum molar ratio of 1.55.

[0032] As shown in Table 1, the difference between Preparation Examples 1-4 is that the silicon-aluminum molar ratio of the carbon dioxide adsorbent is different.

[0033] Table 1 Silicon-aluminum molar ratio of carbon dioxide adsorbent Preparation Example 5 This Preparation Example differs from Preparation Example 3 in that, in the method for preparing the carbon dioxide adsorbent, alkali-melted modified fly ash and acidified clay are added together to a sodium hydroxide solution, the weight of the alkali-melted modified fly ash being 15% of the total weight of the natural clay, and the alkali-melted modified fly ash is prepared according to the following method: Sludge incineration fly ash and sodium hydroxide are mixed in a weight ratio of 8:1, the mixture is heated to melt, cooled, and then ground to obtain alkali-fused modified fly ash.

[0034] The weight percentage composition of the oxides of the alkali-fused modified fly ash is as follows: silicon dioxide 15.5%, aluminum oxide 3.1%, calcium iron oxide Ca2Fe2O5 36.5%, hematite 0.7%, magnetite 25.1%, periclase 9.5%, and the balance is impurities that do not affect performance.

[0035] As shown in Table 2, the difference between Preparation Examples 5-8 is that the percentage of the weight of the alkali-melted modified fly ash to the total weight of the natural clay (referred to as the fly ash percentage) is different.

[0036] Table 2 Fly ash proportion sample Fly ash proportion / % Preparation Example 5 15 Preparation Example 6 20 Preparation Example 7 22 Preparation Example 8 25 Example

[0037] Examples 1-5 The following description will be given using Example 1 as an example.

[0038] Example 1 In this example, the carbon dioxide adsorbent was prepared according to the method of Preparation Example 1.

[0039] This embodiment provides a method for producing high-purity electronic-grade hydrochloric acid, comprising the following steps: (1) Under nitrogen protection, silicon tetrachloride was added to a hydrochloric acid mother liquor with a concentration of 24 wt% (recorded as the mother liquor concentration in Table 3), and the mixture was cooled while stirring the reaction. After the reaction was completed, the product was input into a desorption tower and desorbed under a negative pressure of -0.10 MPa (recorded as the vacuum degree in Table 3). A mixed gas of hydrogen chloride and water vapor was collected from the top of the tower. The mixed gas was found to contain 480 ppm of carbon dioxide. In this step, industrial grade hydrochloric acid was used as the hydrochloric acid mother liquor, and the volume ratio of silicon tetrachloride to the hydrochloric acid mother liquor was 6:1. (2) Under the conditions of an inlet flow rate of 100 L / min and a running time of 3 h, the mixed gas obtained in step (1) was passed into 5 L of a saturated sodium chloride solution for washing, and then the discharged gas was adsorbed using 500 g of a carbon dioxide adsorbent under the conditions of a pressure of 100 kPa and a temperature of 45° C. The tail gas was absorbed by adding water to obtain 27 wt % high-purity dilute hydrochloric acid; in this step, the saturated sodium chloride solution contained undissolved sodium chloride solid, and the amount of sodium chloride solid used was the same as the total amount of solute in the sodium chloride solution; (3) Using 20 wt % sodium chloride solution as the cathode liquid and the anolyte, a hydrogen evolution electrode as the cathode, a platinum electrode as the anode, and a sodium ion exchange membrane as the diaphragm, electrolysis is performed at a voltage of 5 V to obtain hydrogen and chlorine after electrolysis. The hydrogen and chlorine are mixed in a synthesis furnace at a molar ratio of 1.05:1 (denoted as the hydrogen-chlorine ratio in Table 3) and then ignited. The resulting gas is passed into a saturated sodium chloride solution for washing, and then absorbed with the high-purity dilute hydrochloric acid obtained in step (2) to obtain 36 wt % high-purity electronic-grade hydrochloric acid.

[0040] Example 2 The difference between this embodiment and embodiment 1 is that the hydrochloric acid mother liquor also includes a regeneration mother liquor, and the regeneration mother liquor is obtained by filtering the acid solution remaining at the bottom of the decomposition tower and diluting it with water.

[0041] As shown in Table 3, the main difference between Examples 2-4 is that the production parameters of electronic grade hydrochloric acid are different.

[0042] Table 3 sample Example 2 Example 3 Example 4 Mother liquor concentration / wt% 24 25 27 Vacuum degree / MPa -0.05 -0.05 -0.10 Hydrogen-chlorine ratio 1.05:1 1.08:1 1.10:1 Example 4-11 As shown in Table 4, the difference between Examples 4-11 is that the preparation examples of the carbon dioxide adsorbent are different.

[0043] Table 4 Preparation example of carbon dioxide adsorbent Example 12 The difference between this embodiment and embodiment 11 is that the carbon dioxide adsorbent is adsorbed at 40°C.

[0044] Example 13 The difference between this embodiment and embodiment 11 is that the carbon dioxide adsorbent is adsorbed at 35°C.

[0045] Comparative Example Comparative Example 1 This comparative example uses commercially available electronic grade hydrochloric acid as a control.

[0046] Comparative Example 2 The difference between this comparative example and Example 1 is that in step (2) of producing high-purity electronic-grade hydrochloric acid, the mixed gas is only washed without adsorption treatment.

[0047] Comparative Example 3 The difference between this comparative example and Example 1 is that in step (2) of producing high-purity electronic-grade hydrochloric acid, the mixed gas is only subjected to adsorption treatment without washing.

[0048] Comparative Example 4 The difference between this comparative example and Example 1 is that the gas obtained after the combustion reaction of hydrogen and chlorine is directly introduced into high-purity dilute hydrochloric acid for absorption.

[0049] Performance testing methods 1. Routine performance testing Referring to the records of "Q / JL043-2019", various parameters of electronic grade hydrochloric acid were tested, and the results are shown in Table 5.

[0050] 2. Residual carbon dioxide content in mixed gas The residual carbon dioxide content in the gas used to prepare high-purity dilute hydrochloric acid was detected. The results are shown in Table 6.

[0051] 3. Adsorption performance of carbon dioxide adsorbent The adsorption capacity of the carbon dioxide adsorbent for carbon dioxide was tested using an IGA100 gravimetric adsorption instrument at 30°C and 100 kPa. Before the test, the carbon dioxide adsorbent was vacuum dried at 200°C for 8 h to remove moisture. The results are shown in Table 7.

[0052] Table 5 Conventional performance test results Table 6 Residual carbon dioxide content in mixed gas Table 7 Adsorption performance of carbon dioxide adsorbent sample Carbon dioxide absorption / (mmol / g) Preparation Example 1 3.42 Preparation Example 2 3.47 Preparation Example 3 3.51 Preparation Example 4 3.50 Preparation Example 5 4.84 Preparation Example 6 4.93 Preparation Example 7 5.07 Preparation Example 8 5.12 A comparison of Examples 1-11 and Comparative Examples 1-4, along with Table 5, reveals that the iron content in Comparative Example 3 does not meet the required level. This is because when hydrogen and chlorine generated by electrolysis react in the furnace to form hydrogen chloride gas, the chlorine reacts with the steel furnace walls, resulting in the inclusion of ferric chloride vapor in the hydrogen chloride. Furthermore, the tail gas from Comparative Example 3 was not absorbed by a saturated sodium chloride solution, resulting in the ferric chloride vapor being dissolved into the water without being cooled and separated from the hydrogen chloride gas, causing the iron content of the hydrochloric acid to exceed the required level.

[0053] Combining Examples 1-11 with Comparative Examples 2-4 and Table 6 reveals that the mixed gases of Comparative Examples 2-3 all contain relatively high levels of residual carbon dioxide. This is because neither washing with a saturated sodium chloride solution nor absorption with a carbon dioxide adsorbent alone can fully remove carbon dioxide. Only a combination of these two methods can effectively remove titanium dioxide. The electronic-grade hydrochloric acid used in Comparative Examples 2-3, due to the high concentration of carbon dioxide mixed in, is unsuitable for use in processes such as silicon wafer etching, passivation, and epitaxy in integrated circuit production.

[0054] The raw materials used in the method of the present application are from a wide range of sources, including not only industrial-grade chemicals such as industrial-grade hydrochloric acid and industrial-grade sodium chloride, but also waste silicon tetrachloride. The processing steps are relatively simple, which overcomes the defects in the relevant technologies, reduces the production cost of electronic-grade hydrochloric acid, and improves the production efficiency of electronic-grade hydrochloric acid.

[0055] Combining Preparation Example 1 and Preparation Examples 2-4 and Table 7, it can be seen that when the silicon-aluminum molar ratio of the carbon dioxide adsorbent is 1.58-1.64, the measured carbon dioxide absorption is higher. This is because within the above silicon-aluminum molar ratio range, the structure of the carbon dioxide adsorbent is closer to 13X zeolite molecular sieve, which has a better removal effect on carbon dioxide gas. The higher carbon dioxide absorption also helps to reduce the replacement frequency of the carbon dioxide adsorbent.

[0056] Combining Preparation Example 3 and Preparation Example 5 with Table 7, it can be seen that the carbon dioxide absorption capacity measured in Preparation Example 5 is higher. This is because the alkali fusion treatment and hydrothermal treatment enable a large number of pore structures to be formed in the particles of the alkali fusion modified fly ash, thereby increasing the specific surface area of ​​the carbon dioxide adsorbent and being able to more effectively remove the carbon dioxide gas mixed in the hydrogen chloride. The higher carbon dioxide absorption capacity also helps to reduce the replacement frequency of the carbon dioxide adsorbent.

[0057] Combining Preparation Examples 5-8 and Table 7, it can be seen that when the weight of the alkali-melted modified fly ash is 20-25% of the total weight of the natural clay, it helps to increase the specific surface area of ​​the carbon dioxide adsorbent, thereby reducing the replacement frequency of the carbon dioxide adsorbent. The above embodiments are merely explanations of the present application and are not limitations of the present application. After reading this specification, those skilled in the art may make modifications to the embodiments of the present application as needed without any creative contribution. However, as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for producing high-purity electronic-grade hydrochloric acid, characterized in that: The following steps are involved: (1) Under nitrogen protection, silicon tetrachloride is added to a hydrochloric acid mother liquor having a concentration of 24-27 wt%, and the mixture is cooled while stirring the reaction. After the reaction is completed, the product is input into a desorption tower and desorbed under negative pressure. A mixture of hydrogen chloride and water vapor is collected from the top of the tower; in this step, the hydrochloric acid mother liquor includes industrial-grade hydrochloric acid; (2) The mixed gas obtained in step (1) is passed into a saturated sodium chloride solution for washing, and the discharged gas is adsorbed using a carbon dioxide adsorbent. The tail gas is absorbed by adding water to obtain high-purity dilute hydrochloric acid; in this step, the saturated sodium chloride solution contains undissolved sodium chloride solids; (3) Using sodium chloride solution as cathode liquid and anode liquid, a hydrogen evolution electrode as cathode, a platinum electrode as anode, and a sodium ion exchange membrane as a diaphragm, hydrogen and chlorine are obtained after electrolysis, the hydrogen and chlorine are mixed in a synthesis furnace and then ignited, the obtained gas is passed into a saturated sodium chloride solution for washing, and then absorbed with the high-purity dilute hydrochloric acid obtained in step (2) to obtain high-purity electronic grade hydrochloric acid.

2. The method for producing high-purity electronic grade hydrochloric acid according to claim 1, wherein The hydrochloric acid mother liquor also includes a regeneration mother liquor, which is obtained by filtering the acid solution remaining at the bottom of the analytical tower and diluting it with water.

3. The method for producing high-purity electronic grade hydrochloric acid according to claim 1, wherein The carbon dioxide adsorbent is prepared according to the following method: (1) Natural clay is added to hydrochloric acid for heat treatment, then cooled, filtered and washed, and dried to obtain acidified soil; (2) The acidified soil is added to a sodium hydroxide solution, and then a sodium aluminate solution is added and stirred to obtain a raw material liquid. The raw material liquid is added to a reactor for hydrothermal crystallization, and then cooled and filtered. The filter residue is washed with water and dried to obtain a carbon dioxide adsorbent.

4. The method for producing high-purity electronic-grade hydrochloric acid according to claim 3, wherein: The natural clay is attapulgite.

5. The method for producing high-purity electronic-grade hydrochloric acid according to claim 3, wherein: The silicon-aluminum molar ratio of the carbon dioxide adsorbent is 1.58-1.

64.

6. The method for producing high-purity electronic-grade hydrochloric acid according to claim 3, wherein: In the method for preparing the carbon dioxide adsorbent, alkali-melted modified fly ash and acidified soil are added together into a sodium hydroxide solution. The alkali-melted modified fly ash is prepared according to the following method: The sludge incineration fly ash is mixed with sodium hydroxide, the mixture is heated to melt, then cooled, and then ground to obtain alkali-fused modified fly ash.

7. The method for producing high-purity electronic-grade hydrochloric acid according to claim 6, wherein: The weight of the alkali-melted modified fly ash is 20-25% of the total weight of the natural clay.

8. The method for producing high-purity electronic-grade hydrochloric acid according to claim 3, wherein: The carbon dioxide adsorbent performs adsorption at 30-40°C.

9. The method for producing high-purity electronic-grade hydrochloric acid according to claim 1, wherein In step (3), the obtained hydrogen and chlorine are mixed in a molar ratio of (1.05-1.10):

1.

10. The method for producing high-purity electronic grade hydrochloric acid according to claim 1, characterized in that: The vacuum degree during the analysis process of the analysis tower is -(0.05-0.10) MPa.

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