Preparation method of electronic-grade phosphoric acid

Abstract

The invention provides a preparation method of electronic-grade phosphoric acid. The method comprises the following steps: (1) adding a phosphoric acid solution into a crystallization device, then adjusting the crystallization device to be in a micro-positive pressure state under a stirring condition, and controlling the temperature to be 16-22 DEG C; (2) adding a phosphoric acid seed crystal into the crystallization device, cooling to 8-14 DEG C, carrying out suspension melt crystallization, keeping for 0.5-2 hours, then adjusting the crystallization device from a micro-positive pressure state to a vacuum filtration state, and discharging an uncrystallized mother solution; and (3) heating the solid in the crystallization device to a sweating final temperature, maintaining the temperature for 0.5-2 hours, and discharging sweat to obtain the electronic-grade phosphoric acid. The method is simple to operate, low in energy consumption, mild in operation condition and high in product purity, and various impurity ions in the product reach the SEMI C7 standard.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical engineering industrial crystallization, and particularly relates to a preparation method of electronic-grade phosphoric acid. Technical Background Electronic-grade chemicals generally refer to special chemicals supporting the electronics industry. Among them, electronic-grade phosphoric acid, as an ultra-high-purity chemical reagent, occupies an important position in the electronic-grade chemical industry. Electronic-grade phosphoric acid is widely used in wet cleaning and wet etching in the production process of electronic devices such as integrated circuits, thin-film liquid crystal displays, and silicon wafer lithography. Since insoluble solid particles or metal ions may conduct electricity between microcircuits, causing short circuits, electronic-grade phosphoric acid has strict requirements for the content of insoluble solid particles and most metal ions.

[0003] Industrially, food-grade phosphoric acid or preliminarily purified industrial-grade phosphoric acid is often used as a raw material to prepare high-purity electronic-grade phosphoric acid. At present, the common purification methods of phosphoric acid are: solvent extraction method, ion exchange method, electrodialysis method, and crystallization method. The crystallization method refers to the process in which solid substances precipitate in the form of crystals from vapor, solvent, or molten systems, and it is a complex multi-phase, multi-component heat transfer, mass transfer, and surface reaction process. Among them, the melt crystallization method does not require the additional introduction of a third-party solvent, has mild operating conditions, and can obtain good purification effects through two stages of crystallization-sweating, and is regarded as an important research method for the purification of electronic-grade phosphoric acid.

[0004] CN102198937A prepares electronic-grade phosphoric acid by performing multi-stage static melt crystallization in a crystallizer, which requires multi-stage operations in the crystallizer to gradually discharge the mother liquor and sweat, and the preparation cycle reaches 10 h, with a long operation time. CN101774555A adopts a dynamic mode - liquid film crystallization method to prepare electronic-grade phosphoric acid, raises the operating temperature to a suitable temperature range, and performs two liquid film crystallization operations. However, the final metal ion concentration of the obtained electronic-grade phosphoric acid is still relatively high and still needs to be further improved.

[0005] CN103896231A invented a tubular crystallizer for producing electronic-grade phosphoric acid, which suspends the crystals on the vertical tubes. When separating the crystal and liquid phases, the liquid phase with a high content of impurity ions can be completely discharged, solving the problem of mother liquor occlusion and significantly increasing the purification efficiency. However, under static operation, crystals will block the liquid discharge port at the bottom of the crystallizer. CN113842663A connects the crystallization shell and the cooling tube with double constant temperature baths respectively, and sets the cooling tube as a rotating cooling tube, improving the problem that crystals are likely to block the liquid discharge port at the bottom of the static crystallizer. However, this process requires a complex crystallizer structure and two temperature control devices, which may lead to high energy consumption to a certain extent.

[0006] Therefore, it is very necessary to develop a new method for preparing electronic grade phosphoric acid. Summary of the invention

[0007] In view of the shortcomings of the current preparation of electronic-grade phosphoric acid, the present invention provides a method for preparing electronic-grade phosphoric acid using food-grade phosphoric acid as a raw material and a suspension melting device, which realizes the solid-liquid separation of crystals from mother liquor and sweat in the crystallization operation at one time, and crystallization, filtration and washing can be completed in a set of equipment, thereby providing a convenient way to prepare electronic-grade phosphoric acid.

[0008] One of the purposes of the present invention is to provide a method for preparing electronic grade phosphoric acid, the method comprising the following steps: (1) adding a phosphoric acid solution to a crystallization device, and then adjusting the crystallization device to a slightly positive pressure state under stirring conditions, and controlling the temperature to 16-22°C; (2) adding phosphoric acid seed crystals to the crystallization device, and cooling the temperature to 8-14°C for suspension melt crystallization, maintaining the temperature for 0.5-2 h, and then adjusting the crystallization device from the slightly positive pressure state to a vacuum filtration state to discharge the uncrystallized mother liquor; (3) heating the solid in the crystallization device to the sweating end temperature, maintaining the temperature for 0.5-2 h, discharging the sweat, and obtaining electronic grade phosphoric acid.

[0009] Preferably, the crystallization device comprises: a crystallizer, a suction filter bottle connected to the bottom of the crystallizer, and a sand core arranged at the bottom of the crystallizer; The bottom of the crystallizer is provided with an opening which is communicated with the cavity in the suction flask.

[0010] Preferably, the crystallizer is provided with a feed port for adding phosphoric acid solution and phosphoric acid seed crystals; Preferably, a stirring paddle is provided inside the crystallizer, and preferably the stirring paddle is a ribbon paddle; Preferably, a heat exchange jacket is also provided on the outer side wall of the crystallizer for circulating cooling liquid in and out.

[0011] Preferably, the sand core is a G4 specification sand core funnel; Preferably, the suction filter bottle is provided with an opening A and an opening B, wherein the opening A is used to control the crystallization device to be in a slightly positive pressure state, and the opening B is used to control the crystallization device to be in a vacuum state; Preferably, the suction flask is connected to the crystallizer via a snap-fit connection.

[0012] Preferably, the mass fraction of the phosphoric acid solution in step (1) is 80-90%; Preferably, the slightly positive pressure state in step (1) is achieved by closing opening B and opening opening A to allow gas to flow in; Preferably, the gas includes any one of nitrogen, argon, helium, neon, krypton, xenon, radon or carbon dioxide; Preferably, the stirring rate in step (1) is 200 - 400 rpm.

[0013] Preferably, the average particle size of the phosphoric acid seed crystals in step (2) is 0.5 - 1.5 mm; Preferably, based on the addition amount of the phosphoric acid solution being 1320 g, the addition amount of the phosphoric acid seed crystals in step (2) is 0.1 - 1 g.

[0014] Preferably, the vacuum filtration state in step (2) is achieved by closing opening A and opening opening B to evacuate the air; Preferably, the vacuum degree of the vacuum filtration state in step (2) is 0.01 - 0.2 Mpa.

[0015] Preferably, both the heating and sweating in step (3) are carried out under the vacuum filtration state; Preferably, the sweating temperature in step (3) is 18 - 24°C.

[0016] The second object of the present invention is to prepare electronic-grade phosphoric acid according to the preparation method described in the first object; The third object of the present invention is the application of the electronic-grade phosphoric acid described in the second object in integrated circuit cleaning.

[0017] In the present invention, the metal ion impurity content of the phosphoric acid product is analyzed using an industry-recognized inductively coupled plasma optical emission spectrometer (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS).

[0018] The method of the present invention uses a complete set of suspension melting crystallizers to achieve the preparation of electronic-grade phosphoric acid.

[0019] The electronic-grade phosphoric acid obtained by the present invention can be used for cleaning high-end electronic components such as electronic circuit boards and liquid crystal screens.

[0020] Technical features and beneficial effects of the present invention: 1. The present invention uses a suspension melting crystallizer to form phosphoric acid into hexagonal-like crystals through crystallization-sweating, improving the heat exchange rate between phosphoric acid and the cooling medium and accelerating the crystallization speed. This method has low energy consumption, mild operating conditions, high product purity, and directly obtains an electronic-grade phosphoric acid product with a concentration of 88 - 90%, having good market application prospects and industrialization value.

[0021] 2. The present invention effectively avoids the problem of crystal aggregation at the bottom of the crystallizer blocking the liquid discharge port during the static melting crystallization process, and at the same time avoids the serious problem of mother liquor formation due to the formation of a porous structure during the static melting crystallization process, ensuring the high purity of the crystal product and directly obtaining an electronic-grade phosphoric acid product with a concentration of 88 - 90%.

[0022] 3. The process equipment of the present invention is simple and suitable for preparing electronic-grade phosphoric acid, and is expected to achieve further scale-up production. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of a crystallization device; Among them, 1 is a crystallizer; 2 is a suction filter bottle; 3 is a sand core; 4 is a buckle; 11 is a feed inlet; 12 is a stirring paddle; 13 is a heat exchange jacket; 21 is opening A, and 22 is opening B. Detailed Embodiments

[0024] It should be understood that in the description of the present invention, the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more.

[0025] It should be noted that in the description of the present invention, unless otherwise clearly defined and limited, the terms "set", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0026] Those skilled in the art should understand that the present invention necessarily includes the necessary pipelines, conventional valves and general pump equipment for realizing the complete process. However, the above contents do not belong to the main innovation points of the present invention. Those skilled in the art can add and layout them by themselves based on the process flow and equipment structure selection, and the present invention does not make special requirements and specific limitations on this.

[0027] The technical solution of the present invention will be further described below with reference to the drawings and through specific embodiments.

[0028] In a specific embodiment, the present application provides a crystallization device, such as Figure 1As shown: The crystallization device includes a crystallizer 1, a suction flask 2 connected to the bottom of the crystallizer, and a sand core 3 provided at the bottom of the crystallizer; wherein, an opening is provided at the bottom of the crystallizer 1, which communicates with the cavity in the suction flask.

[0029] In some embodiments, a feed inlet 11 is provided at the top of the crystallizer for adding phosphoric acid solution and phosphoric acid seeds; the present application does not specifically limit the number and shape of the feed inlets, and those skilled in the art can adjust according to actual needs.

[0030] In some embodiments, a stirring paddle 12 is provided inside the crystallizer 1 and is stirred under the driving action of a driving device. The present application does not specifically limit the structure of the stirring paddle, and a spiral ribbon paddle is preferably used.

[0031] In some embodiments, a heat exchange jacket 13 is further provided on the outer side wall of the crystallizer for circulating cooling liquid to enter and exit.

[0032] In some embodiments, the sand core 3 is preferably a sand core funnel of G4 specification, and its function is to filter.

[0033] In some embodiments, openings A and B are provided on the suction flask 2. It should be noted that opening A is denoted as 21 and opening B is denoted as 22; wherein opening A is used to control the crystallization device to be in a slightly positive pressure state, and opening B is used to evacuate to make the crystallization device in a vacuum state.

[0034] In some embodiments, the suction flask 2 and the crystallizer 1 are connected by a buckle 4.

[0035] The crystallization device with a specific structure adopted in the present application not only improves the heat exchange rate between phosphoric acid and the cooling medium, but also reduces the crystal fouling on the wall of the crystallizer. At the same time, the suspension operation effectively avoids the problem of crystal blockage of the drain port, and realizes the solid-liquid separation of crystals, mother liquor and sweat in the crystallization operation at one time. At the same time, crystallization, filtration and washing can be completed in a set of devices, reducing the experimental steps and providing a new path for the convenient operation of suspension melting crystallization.

[0036] In some embodiments, based on the above specific crystallization device, a crystallization method is provided, including: (1) Add phosphoric acid solution to the crystallization device, and then under stirring conditions, adjust the crystallization device to a slightly positive pressure state, and control the temperature to be 16 - 22 °C (such as 16 °C, 18 °C, 20 °C, 22 °C, etc.); (2)Add phosphoric acid seeds to the crystallization device, cool down to 8 - 14 °C (such as 8 °C, 10 °C, 12 °C, 14 °C, etc.) for suspension melting crystallization, and maintain for 0.5 - 2 h (such as 0.5 h, 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, etc.). Then, adjust the crystallization device from a slightly positive pressure state to a vacuum filtration state to discharge the uncrystallized mother liquor; (3)Heat the solid in the crystallization device to the sweating end temperature, maintain for 0.5 - 2 h (such as 0.5 h, 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, etc.), discharge the sweat, and obtain electronic-grade phosphoric acid.

[0037] In some embodiments, by opening opening A on the suction flask and closing opening B, introducing gas into opening A to make the state in step (1) slightly positively pressured, thereby preventing the dripping of phosphoric acid liquid; wherein, the gas includes any one of nitrogen, argon, helium, neon, krypton, xenon, radon, or carbon dioxide.

[0038] In some embodiments, the concentration of the phosphoric acid solution in step (1) is 80 - 90%, such as 80%, 82%, 85%, 87%, 90%, etc.

[0039] In some embodiments, the stirring rate in step (1) is 200 - 400 rpm, such as 200 rpm, 220 rpm, 250 rpm, 280 rpm, 300 rpm, 320 rpm, 350 rpm, 380 rpm, 400 rpm, etc.

[0040] In some embodiments, the average particle size of the phosphoric acid seeds in step (2) is 0.5 - 1.5 mm, such as 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, etc.

[0041] In some embodiments, based on the addition amount of the phosphoric acid solution being 660 g, the addition amount of the phosphoric acid seeds in step (2) is 0.1 - 1 g.

[0042] In some embodiments, after the suspension melting crystallization in step (2) is completed, close opening A on the suction flask, open opening B, adjust the pressure in the suction flask to negative pressure, that is, adjust from a slightly positive pressure state to a vacuum filtration state, perform solid-liquid separation on the crystallized mixture, leave the solid on the sand core, and discharge the filtrate; this application does not limit the vacuum degree in the specific vacuum state, and those skilled in the art can adjust it according to actual needs. Preferably, the vacuum degree in the vacuum filtration state is 0.01 - 0.2 Mpa, such as 0.01 MPa, 0.05 MPa, 0.1 MPa, 0.15 MPa, 0.2 MPa, etc.

[0043] In some embodiments, both the heating and the sweating to discharge sweat in step (3) are carried out under vacuum filtration.

[0044] In some embodiments, the sweating temperature in step (3) is 18 - 24 °C, such as 18 °C, 20 °C, 22 °C, 24 °C, etc.

[0045] The preparation method in the present invention is a method for preparing electronic-grade phosphoric acid using food-grade phosphoric acid as a raw material and adopting a specific crystallization device. It realizes the solid-liquid separation of crystals, mother liquor, and sweat in the crystallization operation at one time. Meanwhile, crystallization, filtration, and washing can be completed in a set of devices, providing a convenient way for the preparation of electronic-grade phosphoric acid.

[0046] Example 1: (1) Add a phosphoric acid solution with a mass fraction of 85% as a raw material into the crystallization device. Introduce nitrogen at the bottom to provide a slightly positive pressure. Start the stirring device, keep the stirring rate at 300 rpm, turn on the temperature control device, control the temperature at 16 °C, add 1 g of hemihydrate phosphoric acid crystals (the addition amount of the phosphoric acid solution is 1320 g) into the raw material in the crystallizer, and disperse evenly. (2) Pass in cooling water to cool down. When the temperature drops to 4 °C to reach the crystallization end temperature, keep it constant for 2 h. Change the bottom of the crystallizer from a slightly positive pressure state to vacuum filtration (vacuum degree is 0.1 MPa), and discharge the uncrystallized mother liquor. (3) When the mother liquor in step (2) is completely discharged to obtain crude crystals, start sweating. During the sweating process, the vacuum filtration device keeps working. Heat up to 20 °C to reach the sweating end temperature, and maintain it at the sweating end temperature for 2 h to fully discharge the sweat.

[0047] (4) Raise the temperature of the crystallizer, and melt the crystals in the crystallizer to obtain the final phosphoric acid product.

[0048] Example 2: (1) Add a phosphoric acid solution with a mass fraction of 85% as a raw material into the crystallization device. Introduce nitrogen at the bottom to provide a slightly positive pressure. Start the stirring device, keep the stirring rate at 200 rpm, turn on the temperature control device, control the temperature at 16 °C, add 0.1 g of hemihydrate phosphoric acid crystals (the addition amount of the phosphoric acid solution is 1320 g) into the raw material in the crystallizer, and disperse evenly. (2) Continue to pass in cooling water, cool down to 4 °C to reach the crystallization end temperature, keep it constant for 2 h. Change the bottom of the crystallizer from a slightly positive pressure state to vacuum filtration (vacuum degree is 0.2 MPa), and discharge the uncrystallized mother liquor. (3) When the mother liquor in step (2) is completely discharged, crude crystals are obtained and sweating begins. During the sweating process, the vacuum filtration device continues to work, and the temperature is raised to 24 °C to reach the sweating end temperature, and it is maintained at the sweating end temperature for 2 h to fully discharge the sweat.

[0049] (4) Raise the temperature of the crystallizer, and the crystals in the crystallizer can be melted to obtain the final phosphoric acid product.

[0050] The product test results of the raw materials, Example 1, and Example 2 are shown in Table 1.

[0051] Table 1 Product Test Results of Suspension Melting Crystallization Operations of Raw Material Acid, Example 1, and Example 2 Example 3: (1) Add a phosphoric acid solution with a mass fraction of 85% as the raw material into the crystallization device, introduce nitrogen at the bottom to provide a slightly positive pressure, start the stirring device, the stirring rate is 100 rpm, turn on the temperature control device, control the temperature at 16 °C, add 1 g of hemihydrate phosphoric acid crystals (the addition amount of the phosphoric acid solution is 1320 g) into the raw material of the crystallizer, and disperse evenly; (2) Continuously introduce cooling water into the cooling chamber, cool down to 4 °C to reach the crystallization end temperature, keep it constant for 2 h, change the bottom of the crystallizer from a slightly positive pressure state to vacuum filtration (vacuum degree is 0.1 MPa), and discharge the uncrystallized mother liquor; (3) When the mother liquor in step (2) is completely discharged, crude crystals are obtained and sweating begins. During the sweating process, the vacuum filtration device continues to work, and the temperature is raised to 20 °C to reach the sweating end temperature, and it is maintained at the sweating end temperature for 2 h to fully discharge the sweat.

[0052] (4) Add pure phosphoric acid washing solution for washing, filter by suction, and fully discharge the washing solution.

[0053] (5) Raise the temperature of the crystallizer, and the crystals in the crystallizer can be melted to obtain the final phosphoric acid product.

[0054] Example 4: (1) Add a phosphoric acid solution with a mass fraction of 85% as the raw material into the crystallizer, introduce nitrogen at the bottom to provide a slightly positive pressure, start the stirring device, the stirring rate is 250 rpm, turn on the temperature control device, control the temperature at 16 °C, add 1 g of hemihydrate phosphoric acid crystals (the addition amount of the phosphoric acid solution is 1320 g) into the raw material of the crystallizer, and disperse evenly; (2) Continuously introduce cooling water, cool down to 4 °C to reach the crystallization end temperature, keep it constant for 2 h, change the bottom of the crystallizer from a slightly positive pressure state to vacuum filtration (vacuum degree is 0.05 MPa), and discharge the uncrystallized mother liquor; (3) When the mother liquor in step (2) is completely discharged, crude crystals are obtained and sweating starts. During the sweating process, the vacuum filtration device continues to work. The temperature is raised to 24 °C to reach the sweating end temperature and maintained at the sweating end temperature for 2 h to fully discharge the sweat.

[0055] (4) Add pure phosphoric acid washing solution, wash for 1 h, and filter by suction to fully discharge the washing solution.

[0056] (5) Raise the temperature of the crystallizer, and melt the crystals in the crystallizer to obtain the final phosphoric acid product.

[0057] The product test results of the comparison of raw materials, Example 3, and Example 4 are shown in Table 2.

[0058] Table 2 Product test results of suspension melting crystallization operation of raw material acid, Example 3, and Example 4 As can be seen from Table 1 and Table 2, the electronic-grade phosphoric acid prepared by this method has a very low impurity content; after further washing, the impurity content in the electronic-grade phosphoric acid is further reduced.

[0059] The present invention discloses and provides a suspension melting crystallizer for preparing electronic-grade phosphoric acid and its preparation method. Those skilled in the art can achieve it by referring to the content of this article and appropriately changing links such as the crystallization end temperature, sweating end temperature, and stirring rate. The method of the present invention has been described through preferred embodiments. It is obvious that relevant technicians can make changes or appropriate modifications and combinations to the methods and products described in this article without departing from the content, spirit, and scope of the present invention to implement the technology of the present invention. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are all considered to be included in the spirit, scope, and content of the present invention.

Claims

1. A preparation method of electronic-grade phosphoric acid, characterized in that, The preparation method includes the following steps: (1) Add phosphoric acid solution into the crystallization device, and then under stirring conditions, adjust the crystallization device to a slightly positive pressure state, and control the temperature at 16 - 22 °C; (2) Add phosphoric acid crystal seeds into the crystallization device, and cool down to 8 - 14 °C for suspension melting crystallization, keep it for 0.5 - 2 h, and then adjust the crystallization device from the slightly positive pressure state to the vacuum filtration state to discharge the uncrystallized mother liquor; (3) Heat the solid in the crystallization device to the sweating end temperature, keep it for 0.5 - 2 h, discharge the sweat, and obtain electronic-grade phosphoric acid.

2. The preparation method according to claim 1, wherein The crystallization device includes: a crystallizer, a suction flask connected to the bottom of the crystallizer, and a sand core arranged at the bottom of the crystallizer; an opening is arranged at the bottom of the crystallizer and is communicated with the cavity in the suction flask.

3. The preparation method according to claim 2, characterized in that, A feed inlet is arranged on the crystallizer for adding phosphoric acid solution and phosphoric acid crystal seeds; preferably, a stirring paddle is arranged inside the crystallizer, and preferably the stirring paddle is a helical ribbon paddle; preferably, a heat exchange jacket is also arranged on the outer side wall of the crystallizer for circulating cooling liquid to enter and exit.

4. The preparation method according to claim 2, characterized in that, The sand core is a G4 standard sand core funnel; preferably, an opening A and an opening B are arranged on the suction flask, wherein the opening A is used to control the crystallization device to be in a slightly positive pressure state, and the opening B is used to control the crystallization device to be in a vacuum state; Preferably, the suction flask and the crystallizer are connected by a buckle.

5. The preparation method according to any one of claims 1-4, characterized in that, In step (1), the mass fraction of the phosphoric acid solution is 80 - 90%; preferably, the slightly positive pressure state in step (1) is achieved by closing the opening B and opening the opening A to introduce gas; preferably, the gas includes any one of nitrogen, argon, helium, neon, krypton, xenon, radon or carbon dioxide; preferably, the stirring rate in step (1) is 200 - 400 rpm.

6. The preparation method according to any one of claims 1-4, characterized in that, In step (2), the average particle size of the phosphoric acid crystal seeds is 0.5 - 1.5 mm; preferably, based on the addition amount of the phosphoric acid solution being 1320 g, the addition amount of the phosphoric acid crystal seeds in step (2) is 0.1 - 1 g.

7. The preparation method according to any one of claims 1 to 4, characterized in that, The vacuum filtration state in step (2) is achieved by closing the opening A and opening the opening B to pump vacuum; preferably, the vacuum degree of the vacuum filtration state in step (2) is 0.01 - 0.2 Mpa.

8. The preparation method according to any one of claims 1-4, characterized in that, Both the heating and the discharging of the sweat in step (3) are carried out in the vacuum filtration state; preferably, the sweating temperature in step (3) is 18 - 24 °C.

9. Prepare electronic-grade phosphoric acid according to the preparation method described in any one of claims 1 - 8.

10. Application of the electronic-grade phosphoric acid described in claim 9 in integrated circuit cleaning.

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