Production device and production method of electronic-grade phosphoric acid

Abstract

The production method comprises the following steps: S1, feeding industrial yellow phosphorus into a primary filter for primary filtration, washing, and feeding the industrial yellow phosphorus into a secondary filter for secondary filtration to obtain high-purity yellow phosphorus; s2, the high-purity yellow phosphorus is fed into a combustion tower for oxidative combustion to generate phosphorus pentoxide, ultrapure water is introduced for a hydration reaction to generate a phosphoric acid solution, the phosphoric acid solution is fed into a third-stage filter for third filtration, and arsenic-containing electronic-grade phosphoric acid is obtained; s3, sending the arsenic-containing electronic-grade phosphoric acid into an arsenic removal tank for reaction, removing arsenic salt generated in the reaction, and further removing the arsenic salt through an ultrafiltration system to obtain arsenic-removed electronic-grade phosphoric acid; and S4, blending the arsenic-removed electronic-grade phosphoric acid with ultrapure water, and after blending, feeding into a four-stage filter for fourth filtering to obtain the electronic-grade phosphoric acid. The process can effectively remove impurities of front-end raw materials, middle-end reaction liquid and rear-end products, and the yield of phosphoric acid reaches 95% or above.

Description

Technical Field

[0001] This application relates to the technical field of electronic chemical production, and mainly relates to a production device and a production method of electronic-grade phosphoric acid. Background Art

[0002] Electronic-grade phosphoric acid belongs to high-purity phosphoric acid, which is widely used in microelectronics industries such as large-scale integrated circuits and thin-film liquid crystal displays (TFT-LCDs). It can also be used to prepare high-purity phosphates and is the main raw material for high-purity organic phosphorus products. It is mainly used for the cleaning and etching of chips. Its purity and cleanliness have a great impact on the yield, conductivity, and reliability of electronic components. The lower-purity one is mainly used for the cleaning of liquid crystal panel components, and the higher-purity one is mainly used for the cleaning and etching in the production process of electronic wafers. Since insoluble solid particles or metal ions may conduct current between microcircuits and cause short circuits, electronic-grade phosphoric acid has extremely strict requirements for the content of insoluble solid particles and most metal ions, which also leads to greater separation difficulty.

[0003] Industrial purification methods use food-grade phosphoric acid or preliminarily purified industrial-grade phosphoric acid as raw materials to prepare electronic-grade phosphoric acid, which can be divided into solvent extraction method, ion exchange method, electrodialysis method, crystallization method, etc. Compared with other methods, the crystallization method has the advantages of low energy consumption, simple equipment, low operating cost, and less pollution. However, the electronic-grade phosphoric acid product obtained by this method has relatively low purity and high impurity content. Among them, the content of some metal ions is 5-10 ppb, and the production of low-end electronic-grade phosphoric acid products cannot meet the semiconductor requirements.

[0004] Therefore, it is of great significance to develop a new production device and production method of electronic-grade phosphoric acid with low impurity content and high yield. Summary of the Invention

[0005] In view of the problems in the prior art, this application proposes a production device and a production method of electronic-grade phosphoric acid.

[0006] According to one aspect of this application, a production device of electronic-grade phosphoric acid is proposed, which includes a preliminary impurity removal module, a phosphoric acid solution generation module, an arsenic removal module, and a formulation module connected in sequence; the preliminary impurity removal module includes a yellow phosphorus tank, a primary filter, and an impurity removal tank connected in sequence; the phosphoric acid solution generation module includes a combustion tower; the arsenic removal module includes an arsenic removal tank and an ultrafiltration system; the formulation module includes a phosphoric acid dilution tank; a secondary filter is arranged between the preliminary impurity removal module and the phosphoric acid solution generation module; a tertiary filter is arranged between the phosphoric acid solution generation module and the arsenic removal module; the electronic-grade phosphoric acid is discharged through a quaternary filter.

[0007] The device effectively reduces the impurity content of the front-end raw materials, middle-end reaction solution and back-end products, and significantly improves the purity of electronic-grade phosphoric acid. Among them, after being washed with a detergent and ultrapure water, most of the organic and inorganic impurities in industrial yellow phosphorus are removed, providing a good basis for subsequent filtration. The setting of the multi-stage filter ensures that the impurities generated after each reaction can be effectively removed, avoiding the accumulation and amplification effect of impurities in subsequent reactions. In addition, by precisely controlling the reaction conditions and selecting high-quality filter element materials, the production efficiency and product quality of electronic-grade phosphoric acid can be further improved. Through this new production method, an electronic-grade phosphoric acid product of semiconductor grade with a concentration of 85% can be obtained, and the phosphoric acid yield reaches 98%.

[0008] Preferably, the combustion tower is provided with a cooler for cooling the refluxed phosphoric acid solution.

[0009] In a specific embodiment, an ultrapure water spraying device and a phosphoric acid solution cooling spraying device are respectively arranged at the top of the combustion tower. The refluxed phosphoric acid solution enters the combustion tower through the phosphoric acid solution cooling spraying device after being cooled by the cooler, and the cross-sectional area of the sprayed water mist completely covers the cross-sectional area of the combustion tower. By concentrating the oxidation combustion reaction of high-purity yellow phosphorus and the hydration reaction of phosphorus pentoxide in one device, this solution simplifies the production process, and uses the phosphoric acid solution cooling spraying device at the top of the combustion tower to cool and absorb phosphorus pentoxide, which not only effectively controls the reaction temperature, but also ensures the production efficiency and purity of the phosphoric acid solution.

[0010] Preferably, the arsenic removal module further includes an arsenic salt collection tank, and the arsenic removal tank and the ultrafiltration system are respectively connected to the arsenic salt collection tank.

[0011] In a specific embodiment, by adding an arsenic salt collection tank, the arsenic salts generated by the reaction can be collected and processed centrally, thereby avoiding the residue and secondary pollution of arsenic salts in the system, and further improving the purity of electronic-grade phosphoric acid. At the same time, this setting also facilitates the recovery and utilization of arsenic salts, which conforms to the development trend of green chemistry and circular economy. In addition, the introduction of the arsenic salt collection tank also optimizes the production process and improves the production efficiency.

[0012] Preferably, the housing materials of the primary filter and the secondary filter include SS316L; the housing materials of the tertiary filter and the quaternary filter include SS316L and PFA. SS316L stainless steel has good corrosion resistance, high-temperature resistance and mechanical strength, which can effectively prevent the filter housing from being corroded or deformed during the reaction process, ensuring the long-term stable operation of the filter. And PFA (perfluoroalkoxy ethylene) also has excellent high-temperature and chemical corrosion resistance. The housing design of the tertiary filter and the quaternary filter with SS316L lined with PFA can more effectively resist the erosion of corrosive media such as phosphoric acid, further improving the service life and safety of the filter. In addition, PFA material can effectively avoid the introduction of metal impurities by the equipment material itself, ensuring the purity of the filtered product.

[0013] Preferably, the filter element materials of the primary filter, the secondary filter, the tertiary filter and the quaternary filter include one of PTFE, N-PTFE and PFA. The above materials have excellent corrosion resistance and high-temperature resistance. The filter elements prepared with the above materials can effectively resist the erosion of corrosive media such as phosphoric acid, and can effectively avoid the introduction of metal impurities by the equipment material itself.

[0014] Preferably, the number of filter elements of the primary filter includes one of 3 cores and 5 cores; the number of filter elements of the secondary filter, the tertiary filter and the quaternary filter includes one of 3 cores, 5 cores and 12 cores. This design not only ensures sufficient filtration area, but also can flexibly adjust the number of filter elements according to actual needs to meet the requirements of filtration accuracy in different production stages. At the same time, the multi-core design also helps to improve the filtration efficiency and shorten the production cycle.

[0015] According to the second aspect of the present application, a production method of electronic-grade phosphoric acid is proposed, including the following steps:

[0016] S1. Feed industrial yellow phosphorus into the primary filter for primary filtration, then wash it with a detergent and ultrapure water, and after washing, feed it into the secondary filter for secondary filtration to obtain high-purity yellow phosphorus. The detergent is selected from one of H 2 O 2 、H 2 SO 4 and HNO 3 ;

[0017] S2. Feed the high-purity yellow phosphorus into the combustion tower for oxidative combustion to generate phosphorus pentoxide, and introduce ultrapure water into the combustion tower to carry out a hydration reaction with the phosphorus pentoxide to generate a phosphoric acid solution. Feed the phosphoric acid solution into the tertiary filter for the third filtration to obtain arsenic-containing electronic-grade phosphoric acid;

[0018] S3. React the arsenic-containing electronic-grade phosphoric acid with an arsenic removal additive to remove the arsenic salts generated by the reaction, and filter the arsenic-removed electronic-grade phosphoric acid through an ultrafiltration system to further remove the arsenic salts, obtaining arsenic-removed electronic-grade phosphoric acid. The arsenic removal additive includes sulfuric acid and one selected from Na 2 S and Ca 2 S;

[0019] S4. Blend the arsenic-removed electronic-grade phosphoric acid with ultrapure water, and feed the blended solution into a four-stage filter for a fourth filtration to obtain electronic-grade phosphoric acid.

[0020] In a specific embodiment, H 2 O 2 、H 2 SO 4 and HNO 3 all have strong oxidizing properties and can effectively remove organic and inorganic impurities on the surface of industrial yellow phosphorus, improving the subsequent filtration efficiency.

[0021] In a specific embodiment, sulfuric acid, Na 2 S and Ca 2 S as the arsenic removal additive can react with the impurity arsenic in the electronic-grade phosphoric acid to generate arsenic salts such as arsenic sulfide and calcium arsenate, thereby removing the impurity arsenic.

[0022] Preferably, the specific steps of S2 include:

[0023] S21. Feed the high-purity yellow phosphorus into the top of the combustion tower through a nozzle, atomize the high-purity yellow phosphorus through clean air, and oxidize and burn the high-purity yellow phosphorus to generate high-temperature phosphorus pentoxide;

[0024] S22. Spray ultrapure water through the ultrapure water spraying device at the top of the combustion tower to cool and absorb the phosphorus pentoxide, generating the phosphoric acid solution;

[0025] S23. Divide the phosphoric acid solution into two streams. One stream is cooled by a cooler and then returned to the top of the combustion tower, and enters the combustion tower again in the form of spraying. The other stream is fed into the three-stage filter for a third filtration to obtain the arsenic-containing electronic-grade phosphoric acid.

[0026] Preferably, in S3, the reaction pressure is 0.1 - 0.2 MPa and the reaction temperature is room temperature. Under these reaction conditions, the reaction rate can be effectively controlled to ensure the full reaction of arsenic with hydrogen sulfide, and at the same time, the occurrence of side reactions caused by too high temperature and pressure is avoided, thereby improving the arsenic removal efficiency and product quality.

[0027] Preferably, the impurity content of the industrial yellow phosphorus after being filtered by the primary filter is 20 - 50 ppb; the impurity content of the electronic-grade phosphoric acid includes 1 - 5 ppb and not more than 1 ppb; the impurities with a content of 1 - 5 ppb include aluminum, antimony, arsenic, copper, and iron; the impurities with a content of not more than 1 ppb include barium, cadmium, calcium, chromium, cobalt, gold, lead, lithium, magnesium, manganese, nickel, potassium, silver, sodium, strontium, titanium, and zinc.

[0028] In a specific embodiment, the impurity content is reduced from 100 - 200 ppb to 20 - 50 ppb by the primary filter, which is beneficial to the further purification of the subsequent filtration system, reduces the difficulty of impurity treatment in the overall process, and improves production efficiency. The filtration system in which the secondary filter, the tertiary filter, and the quaternary filter are connected in series can effectively reduce the content of metal ions and insoluble solid particles to 1 - 5 ppb, or even below 1 ppb, which greatly improves the purity and quality of the finished product, meets the strict requirements of high-end electronic-grade phosphoric acid products, and provides high-quality raw material guarantee for microelectronics industries such as large-scale integrated circuits and thin-film liquid crystal displays.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] (1) In the initial stage of the process of the present application, a large number of impurities in the industrial yellow phosphorus are effectively removed by the strong oxidizing properties of solutions such as H 2 O 2 , H 2 SO 4 , and HNO 3 , and the raw materials are efficiently purified;

[0031] (2) The solution of the present application effectively reduces the impurity content to only 1 - 5 ppb, or even lower than 1 ppb, by multi-stage filtration, reasonable and effective process technologies, and strict equipment requirements, meets the strict requirements of high-end electronic-grade phosphoric acid products, and the phosphoric acid yield reaches more than 95%;

[0032] (3) The present application conducts the oxidation combustion reaction of high-purity yellow phosphorus and the hydration reaction of phosphorus pentoxide in one device, simplifies the production process, and uses the cooling phosphoric acid solution spraying device at the top of the combustion tower to cool and absorb phosphorus pentoxide, which not only effectively controls the reaction temperature but also ensures the production efficiency and purity of the phosphoric acid solution. Description of the Drawings

[0033] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate the embodiments and, together with the description, are used to explain the principles of the present application. Other embodiments and many of the intended advantages of the embodiments will be readily apparent as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale with each other. Like reference numerals refer to corresponding like parts.

[0034] Figure 1 The schematic diagram of a production device for electronic-grade phosphoric acid according to an embodiment of the present application is shown;

[0035] Figure 2 The production method of electronic-grade phosphoric acid according to a specific embodiment of the present application is shown.

[0036] The reference numerals are as follows:

[0037] 1 - yellow phosphorus tank; 2 - transfer pump; 3 - primary filter; 4 - impurity removal tank; 5 - transfer pump; 6 - secondary filter; 7 - combustion tower; 8 - transfer pump; 9 - tertiary filter; 10 - arsenic removal tank; 11 - transfer pump; 12 - ultrafiltration system; 13 - transfer pump; 14 - arsenic salt collection tank; 15 - phosphoric acid dilution tank; 16 - transfer pump; 17 - quaternary filter; 18 - cooler; 19 - arsenic removal additive storage tank. Detailed Description of the Embodiments

[0038] The present application will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention and are not intended to limit the present application. Additionally, it should be noted that for ease of description, only the parts related to the relevant invention are shown in the drawings.

[0039] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and embodiments.

[0040] Reference Figure 1 , a production device for electronic-grade phosphoric acid:

[0041] It includes a preliminary impurity removal module, a phosphoric acid solution generation module, an arsenic removal module, and a formulation module connected in sequence; the preliminary impurity removal module includes a yellow phosphorus tank 1, a transfer pump 2, a primary filter 3, and an impurity removal tank 4 connected in sequence; the phosphoric acid solution generation module includes a combustion tower 7; the arsenic removal module includes an arsenic removal tank 10, an arsenic removal additive storage tank 19, and an ultrafiltration system 12; the formulation module includes a phosphoric acid dilution tank 15; a transfer pump 5 and a secondary filter 6 are connected in sequence between the preliminary impurity removal module and the phosphoric acid solution generation module; a transfer pump 8 and a tertiary filter 9 are connected in sequence between the phosphoric acid solution generation module and the arsenic removal module; electronic-grade phosphoric acid is discharged through a quaternary filter 17.

[0042] Preferably, the combustion tower 7 is provided with a cooler 18. The refluxed phosphoric acid solution enters the combustion tower 7 after being cooled by the cooler 18. The top of the combustion tower 7 is also provided with an ultrapure water spraying device and a cooled phosphoric acid solution spraying device, and the cross-sectional area of the sprayed water mist completely covers the cross-sectional area of the combustion tower 7.

[0043] Preferably, the arsenic removal module further includes an arsenic salt collection tank 14. The arsenic removal additive storage tank 19 is connected to the arsenic removal tank 10 through a pipeline, and then connected to the arsenic salt collection tank 14 through a pipeline in sequence via a transfer pump 13. At the same time, the arsenic removal tank 10 is also connected to the ultrafiltration system 12 through a pipeline in sequence via a transfer pump 11. In addition, the ultrafiltration system 12 is also connected to the arsenic salt collection tank 14 through a pipeline.

[0044] Preferably, the housing materials of the primary filter and the secondary filter are SS316L; the housings of the tertiary filter and the quaternary filter include an SS316L outer shell and a PFA lining.

[0045] Preferably, the filter element materials of the primary filter 3, the secondary filter 6, the tertiary filter 9, and the quaternary filter 17 include one of PTFE, N-PTFE, and PFA.

[0046] Preferably, the number of filter elements of the primary filter 3 includes one of 3 cores and 5 cores; the number of filter elements of the secondary filter 6, the tertiary filter 9, and the quaternary filter 17 includes one of 3 cores, 5 cores, and 12 cores.

[0047] Figure 2 Shows a flow chart of a production method of electronic-grade phosphoric acid, as Figure 2 shown, the specific process steps are as follows:

[0048] S1. Feed industrial yellow phosphorus into the primary filter 3 for primary filtration, then wash it with a detergent and ultrapure water, and after washing, feed it into the secondary filter 6 for secondary filtration to obtain high-purity yellow phosphorus. The detergent is selected from one of H 2 O 2 、H 2 SO 4 and HNO 3 ;

[0049] S2. Feed high-purity yellow phosphorus into the combustion tower 7 for oxidation combustion to generate phosphorus pentoxide, and introduce ultrapure water into the combustion tower 7 to carry out a hydration reaction with phosphorus pentoxide to generate a phosphoric acid solution. Feed the phosphoric acid solution into the tertiary filter 9 for a third filtration to obtain arsenic-containing electronic-grade phosphoric acid;

[0050] S3. React the arsenic-containing electronic-grade phosphoric acid with an arsenic removal additive to remove the arsenic salt generated by the reaction, and filter the arsenic-removed electronic-grade phosphoric acid through an ultrafiltration system to further remove the arsenic salt to obtain arsenic-removed electronic-grade phosphoric acid. The arsenic removal additive includes sulfuric acid and one selected from Na 2 S and Ca 2 S;

[0051] S4. Blend the arsenic-removed electronic-grade phosphoric acid with ultrapure water, and feed the blended solution into the quaternary filter 17 for a fourth filtration to obtain electronic-grade phosphoric acid.

[0052] In a specific embodiment, the specific process of a method for producing electronic-grade phosphoric acid is as follows:

[0053] First, feed the industrial yellow phosphorus stored in the yellow phosphorus tank 1 into the primary filter 3 for primary filtration to remove some particles in the industrial yellow phosphorus. After primary filtration, directly feed the filtrate into the impurity removal tank 4; then, introduce one of H 2 O 2 , H 2 SO 4 and HNO 3 and ultrapure water into the impurity removal tank 4 in sequence to wash the industrial yellow phosphorus to obtain high-purity yellow phosphorus; the washed high-purity yellow phosphorus is then fed into the secondary filter 6 through the delivery pump 5 for a second filtration to further control the impurity content in the high-purity yellow phosphorus.

[0054] The high-purity yellow phosphorus after secondary impurity removal is fed into the interior of the combustion tower through the nozzle at the top of the combustion tower 7. At the same time, clean air is injected from the top of the tower to atomize the high-purity yellow phosphorus, so that the high-purity yellow phosphorus undergoes oxidation combustion to generate high-temperature phosphorus pentoxide; then, ultrapure water is introduced into the combustion tower 7, and the ultrapure water absorbs and cools the high-temperature phosphorus pentoxide to generate a phosphoric acid solution; the phosphoric acid solution is divided into two streams. One stream is cooled by the cooler 18 and then returns to the top of the combustion tower 7 and is sprayed out through the cooling phosphoric acid solution spraying device; the other stream of phosphoric acid solution is fed into the tertiary filter 9 through the delivery pump 8 for a third filtration to obtain arsenic-containing electronic-grade phosphoric acid, which is then fed into the arsenic removal tank 10.

[0055] After the third filtration, the arsenic-containing electronic-grade phosphoric acid and the arsenic removal additive in the arsenic removal additive storage tank 19 are fed into the arsenic removal tank 10 together for reaction. The arsenic removal additive storage tank 19 stores sulfuric acid, as well as Na 2 S, Ca2 One of those in S. Inside the arsenic removal tank 10, the mass fraction of arsenic-containing electronic-grade phosphoric acid is 85%. The pressure inside the arsenic removal tank is 0.15 MPa, and the temperature is kept at room temperature. Inside the arsenic removal tank 10, impurities in the arsenic-containing electronic-grade phosphoric acid react to form precipitates such as arsenic sulfide, and thus the arsenic impurities in the electronic-grade phosphoric acid are removed. The precipitates such as arsenic sulfide formed by the reaction are sent into the arsenic salt collection tank 14 through the transfer pump 13; while the arsenic-removed electronic-grade phosphoric acid is sent into the ultrafiltration system 12 through the transfer pump 11 for ultrafiltration. After being filtered by the ultrafiltration membrane, a small amount of impurities such as arsenic salts mixed in the electronic-grade phosphoric acid are removed, further improving the purity of the electronic-grade phosphoric acid, and the arsenic salts filtered out by the ultrafiltration system 12 are still sent into the arsenic salt collection tank 14.

[0056] The electronic-grade phosphoric acid after being filtered by the ultrafiltration membrane directly enters the phosphoric acid dilution tank 15, and ultrapure water is injected into the phosphoric acid dilution tank 15 to prepare the electronic-grade phosphoric acid. The prepared electronic-grade phosphoric acid is injected into the four-stage filter 17 through the transfer pump 16 for the fourth filtration, further reducing the impurity content in the electronic-grade phosphoric acid, and obtaining semiconductor-grade electronic-grade phosphoric acid with a concentration of 85%.

[0057] The specific implementation manners of the present application have been described above, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A production device for electronic grade phosphoric acid, characterized in that: It comprises a preliminary impurity removal module, a phosphoric acid solution generating module, an arsenic removal module and a mixing module which are connected in sequence; the preliminary impurity removal module comprises a yellow phosphorus tank, a primary filter and an impurity removal tank which are connected in sequence; the phosphoric acid solution generating module comprises a combustion tower; the arsenic removal module comprises an arsenic removal tank and an ultrafiltration system; the mixing module comprises a phosphoric acid dilution tank; a secondary filter is arranged between the preliminary impurity removal module and the phosphoric acid solution generating module; a tertiary filter is arranged between the phosphoric acid solution generating module and the arsenic removal module; the electronic grade phosphoric acid is discharged through a quaternary filter.

2. The production device of electronic grade phosphoric acid according to claim 1, characterized in that: The combustion tower is provided with a cooler for cooling the refluxed phosphoric acid solution.

3. The production device of electronic grade phosphoric acid according to claim 1, characterized in that: The arsenic removal module also includes an arsenic salt collection tank, and the arsenic removal tank and the ultrafiltration system are respectively connected to the arsenic salt collection tank.

4. The production device of electronic grade phosphoric acid according to claim 1, characterized in that: The shell materials of the primary filter and the secondary filter include SS316L; the shell materials of the tertiary filter and the quaternary filter include SS316L and PFA.

5. The production device of electronic grade phosphoric acid according to claim 1, characterized in that: The filter element material of the primary filter, the secondary filter, the tertiary filter and the quaternary filter includes one of PTFE, N-PTFE and PFA.

6. The production device of electronic grade phosphoric acid according to claim 1, characterized in that: The number of filter elements of the primary filter includes one of 3 cores and 5 cores; the number of filter elements of the secondary filter, the tertiary filter and the quaternary filter includes one of 3 cores, 5 cores and 12 cores.

7. A method for producing electronic grade phosphoric acid, characterized in that: The following steps are involved: S1, sending industrial yellow phosphorus into a primary filter for primary filtration, then washing with detergent and ultrapure water, and then sending it into a secondary filter for secondary filtration to obtain high-purity yellow phosphorus, wherein the detergent is selected from one of H2O2, H2SO4 and HNO3; S2, sending the high-purity yellow phosphorus into a combustion tower for oxidation and combustion to generate phosphorus pentoxide, and introducing ultrapure water into the combustion tower for hydration reaction with the phosphorus pentoxide to generate a phosphoric acid solution, and sending the phosphoric acid solution into a three-stage filter for filtering for the third time to obtain arsenic-containing electronic grade phosphoric acid; S3, reacting the arsenic-containing electronic-grade phosphoric acid with an arsenic removal additive to remove the arsenic salt generated by the reaction, and filtering the electronic-grade phosphoric acid after arsenic removal through an ultrafiltration system to further remove the arsenic salt to obtain arsenic-removed electronic-grade phosphoric acid, wherein the arsenic removal additive includes sulfuric acid and one selected from Na2S and Ca2S; S4, mixing the arsenic-removing electronic-grade phosphoric acid with ultrapure water, and sending the mixed solution into a four-stage filter for a fourth filtration to obtain electronic-grade phosphoric acid.

8. The method for producing electronic grade phosphoric acid according to claim 7, characterized in that: The specific steps of S2 include: S21, the high-purity yellow phosphorus is sent into the top of the combustion tower through a nozzle, and the high-purity yellow phosphorus is atomized by clean air, so that the high-purity yellow phosphorus is oxidized and burned to generate high-temperature phosphorus pentoxide; S22, spraying ultrapure water through the ultrapure water spraying device at the top of the combustion tower to cool and absorb the phosphorus pentoxide to generate the phosphoric acid solution; S23, dividing the phosphoric acid solution into two streams, one stream is cooled by a cooler, then refluxes to the top of the combustion tower, and enters the combustion tower again in the form of spraying, and the other stream is sent to the three-stage filter for a third filtration to obtain the arsenic-containing electronic-grade phosphoric acid.

9. The method for producing electronic grade phosphoric acid according to claim 7, characterized in that: In S3, the reaction pressure is 0.1-0.2 MPa.

10. The method for producing electronic grade phosphoric acid according to claim 7, characterized in that: The impurity content of the industrial yellow phosphorus after filtering through the primary filter is 20-50 ppb; the impurity content of the electronic grade phosphoric acid includes 1-5 ppb and no more than 1 ppb; the impurities with a content of 1-5 ppb include aluminum, antimony, arsenic, copper and iron; the impurities with a content of no more than 1 ppb include barium, cadmium, calcium, chromium, cobalt, gold, lead, lithium, magnesium, manganese, nickel, potassium, silver, sodium, strontium, titanium and zinc.

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