Production device of electronic-grade phosphoric acid

Abstract

The production device comprises a primary impurity removal module, a phosphoric acid solution generation module, an arsenic removal module and a blending module which are connected in sequence, the primary 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 generation module comprises a combustion tower; the arsenic removal module comprises an arsenic removal tank and an ultrafiltration system; the blending module comprises a phosphoric acid dilution tank; a secondary filter is arranged between the primary impurity removal module and the phosphoric acid solution generation module; a three-stage filter is arranged between the phosphoric acid solution generation module and the arsenic removal module; and the electronic-grade phosphoric acid is discharged through the four-stage filter. The device 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 field of electronic chemical production technology, and mainly to a production apparatus for electronic-grade phosphoric acid. Background Technology

[0002] Electronic-grade phosphoric acid is a high-purity phosphoric acid widely used in the microelectronics industry, including large-scale integrated circuits and thin-film liquid crystal displays (TFT-LCDs). It is also used to prepare high-purity phosphates and is a major raw material for high-purity organophosphorus products. Primarily used for chip cleaning and etching, its purity and cleanliness significantly impact the yield, conductivity, and reliability of electronic components. Lower-purity phosphoric acid is mainly used for cleaning LCD panel components, while higher-purity phosphoric acid is primarily used for cleaning and etching in the electronic wafer manufacturing process. Because insoluble solid particles or metal ions can conduct current between microcircuits, causing short circuits, electronic-grade phosphoric acid has extremely stringent requirements regarding the content of insoluble solid particles and most metal ions, which leads to significant separation challenges.

[0003] Industrial purification methods use food-grade phosphoric acid or pre-purified industrial-grade phosphoric acid as raw materials to prepare electronic-grade phosphoric acid. These methods can be categorized into solvent extraction, ion exchange, electrodialysis, and crystallization. Compared to the other methods, crystallization offers advantages such as low energy consumption, simple equipment, low operating costs, and low pollution. However, the resulting electronic-grade phosphoric acid product has low purity and high impurity content; some metal ions contain 5-10 ppb, producing low-end electronic-grade phosphoric acid that cannot meet semiconductor requirements.

[0004] Therefore, it is of great significance to develop new production equipment for electronic-grade phosphoric acid with low impurity content and high yield. Utility Model Content

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

[0006] To achieve the above objectives, this application proposes a production apparatus for electronic-grade phosphoric acid, comprising a preliminary impurity removal module, a phosphoric acid solution generation module, an arsenic removal module, and a blending 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, an arsenic removal additive storage tank, and an ultrafiltration system; the blending module includes a phosphoric acid dilution tank; a secondary filter is provided between the preliminary impurity removal module and the phosphoric acid solution generation module; a tertiary filter is provided between the phosphoric acid solution generation module and the arsenic removal module; and the electronic-grade phosphoric acid is discharged through a quaternary filter.

[0007] This device effectively reduces the impurity content of upstream raw materials, intermediate reaction solutions, and downstream products, significantly improving the purity of electronic-grade phosphoric acid. Specifically, washing with detergent and ultrapure water removes most of the organic and inorganic impurities from industrial yellow phosphorus, providing a good foundation for subsequent filtration. The multi-stage filtration system ensures effective removal of impurities generated after each reaction step, preventing the accumulation and amplification of impurities in subsequent reactions. Furthermore, precise control of reaction conditions and the selection of high-quality filter cartridge materials further improve the production efficiency and product quality of electronic-grade phosphoric acid. This novel production method can produce semiconductor-grade electronic-grade phosphoric acid with a concentration of 85% and a phosphoric acid yield of 98%.

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

[0009] In a specific embodiment, an ultrapure water spray device and a cooling phosphoric acid solution spray device are respectively installed at the top of the combustion tower. The reflux phosphoric acid solution is cooled by a cooler and then enters the combustion tower through the cooling phosphoric acid solution spray device. The cross-sectional area of ​​the sprayed water mist completely covers the cross-sectional area of ​​the combustion tower. By concentrating the oxidation and combustion reaction of high-purity yellow phosphorus and the hydration reaction of phosphorus pentoxide in one device, this scheme simplifies the production process. Moreover, by using the cooling phosphoric acid solution spray device at the top of the combustion tower to cool and absorb phosphorus pentoxide, not only is the reaction temperature effectively controlled, but the efficiency and purity of phosphoric acid solution generation are also ensured.

[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 in the reaction can be collected and processed centrally, thereby avoiding arsenic salt residue and secondary pollution in the system, and further improving the purity of electronic-grade phosphoric acid. At the same time, this setup also facilitates the recovery and utilization of arsenic salts, aligning with the development trends of green chemistry and the circular economy. Furthermore, the introduction of the arsenic salt collection tank optimizes the production process and improves production efficiency.

[0012] Preferably, the housing material of the primary filter and the secondary filter comprises SS316L; the housing material of the tertiary filter and the quaternary filter comprises 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. PFA (perfluoroalkoxyethylene) also has excellent high temperature resistance and chemical corrosion resistance. The tertiary and quaternary filters adopt an SS316L housing lined with PFA, which 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 prevent the introduction of metallic impurities from the equipment material itself, ensuring the purity of the filtered product.

[0013] Preferably, 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. These materials possess excellent corrosion resistance and high-temperature resistance. Using filter elements made from these materials can extend the service life of the filters and effectively prevent the introduction of metallic impurities from the equipment materials themselves.

[0014] Preferably, the primary filter has one of three or five filter elements; the secondary, tertiary, and quaternary filters have one of three, five, or twelve filter elements. This design not only ensures sufficient filtration area but also allows for flexible adjustment of the number of filter elements to meet the filtration accuracy requirements of different production stages. Furthermore, the multi-element design helps improve filtration efficiency and shorten the production cycle.

[0015] Compared with the prior art, this application has the following beneficial effects:

[0016] (1) The solution of this application effectively reduces the impurity content through multi-stage filtration, reasonable and effective process technology and strict equipment requirements. The impurity content is only 1-5 ppb, or even less than 1 ppb, which meets the strict requirements of high-end electronic grade phosphoric acid products, and the phosphoric acid yield is over 95%.

[0017] (2) The present application integrates the oxidation and combustion reaction of high-purity yellow phosphorus and the hydration reaction of phosphorus pentoxide into one device, which simplifies the production process. Moreover, the phosphorus pentoxide is cooled and absorbed by the cooling phosphoric acid solution spray device at the top of the combustion tower, which not only effectively controls the reaction temperature, but also ensures the generation efficiency and purity of the phosphoric acid solution. Attached Figure Description

[0018] 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 embodiments and, together with the description, serve to explain the principles of this application. Other embodiments and many anticipated advantages of these embodiments will be readily recognized as they become better understood through reference to the following detailed description. Elements in the drawings are not necessarily to scale. The same reference numerals refer to corresponding similar parts.

[0019] Figure 1 A schematic diagram of an apparatus for producing electronic-grade phosphoric acid according to an embodiment of this application is shown.

[0020] The attached figures are labeled as follows:

[0021] 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-Fourth-stage filter; 18-Cooler; 19-Arsenic removal additive storage tank. Detailed Implementation

[0022] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not intended to limit the scope of the application. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] refer to Figure 1 An apparatus for producing electronic-grade phosphoric acid:

[0025] The system includes a preliminary impurity removal module, a phosphoric acid solution generation module, an arsenic removal module, and a blending 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 blending 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.

[0026] Preferably, the combustion tower 7 is equipped with a cooler 18. The refluxed phosphoric acid solution is cooled by the cooler 18 before entering the combustion tower 7. The top of the combustion tower 7 is also equipped with an ultrapure water spray device and a cooling phosphoric acid solution spray device. The cross-sectional area of ​​the spray water mist completely covers the cross-sectional area of ​​the combustion tower 7.

[0027] Preferably, the arsenic removal module further includes an arsenic salt collection tank 14, and an arsenic removal additive storage tank 19 is connected to the arsenic removal tank 10 via a pipeline, and then connected to the transfer pump 13 and the arsenic salt collection tank 14 in sequence via a pipeline. At the same time, the arsenic removal tank 10 is also connected to the transfer pump 11 and the ultrafiltration system 12 in sequence via a pipeline. In addition, the ultrafiltration system 12 is also connected to the arsenic salt collection tank 14 via a pipeline.

[0028] Preferably, the housing material of the primary and secondary filters is SS316L; the housing of the tertiary and quaternary filters includes an SS316L outer shell and a PFA inner liner.

[0029] Preferably, the filter elements of the primary filter 3, secondary filter 6, tertiary filter 9 and quaternary filter 17 are made of PTFE.

[0030] Preferably, the primary filter 3 has 5 filter elements; the secondary filter 6, the tertiary filter 9, and the quaternary filter 17 each have 12 filter elements.

[0031] In a specific embodiment, the production process of electronic-grade phosphoric acid is as follows:

[0032] First, the industrial yellow phosphorus stored in yellow phosphorus tank 1 is sent to primary filter 3 via transfer pump 2 for initial filtration to remove some particles from the industrial yellow phosphorus. After the initial filtration, the filtrate is directly sent to impurity removal tank 4; then, detergent and ultrapure water are sequentially injected into impurity removal tank 4 to wash the industrial yellow phosphorus, obtaining high-purity yellow phosphorus; the washed high-purity yellow phosphorus is then sent to secondary filter 6 via transfer pump 5 for a second filtration to further control the impurity content in the high-purity yellow phosphorus.

[0033] After undergoing secondary impurity removal, the high-purity yellow phosphorus is fed into the combustion tower 7 through a nozzle at the top of the tower. Simultaneously, clean air is injected from the top of the tower to atomize the high-purity yellow phosphorus, causing it to oxidize and burn to generate high-temperature phosphorus pentoxide. Then, ultrapure water is introduced into the combustion tower 7 to absorb and cool the high-temperature phosphorus pentoxide, generating a phosphoric acid solution. The phosphoric acid solution is divided into two streams. One stream is cooled by the cooler 18 and then flows back into the cooling phosphoric acid solution spray device at the top of the combustion tower 7 for spraying. The other stream of phosphoric acid solution is sent to the three-stage filter 9 by the transfer pump 8 for a third filtration to obtain arsenic-containing electronic-grade phosphoric acid, which is then sent to the arsenic removal tank 10.

[0034] After the third filtration, the arsenic-containing electronic-grade phosphoric acid and the arsenic removal additive are fed into the arsenic removal tank 10 for reaction. The arsenic removal additive is stored in the arsenic removal additive storage tank 19. Inside the arsenic removal tank 10, the mass fraction of the arsenic-containing electronic-grade phosphoric acid is 85%, the pressure inside the tank is 0.15 MPa, and the temperature is maintained at room temperature. Inside the arsenic removal tank 10, the arsenic removal additive reacts with impurities in the arsenic-containing electronic-grade phosphoric acid to form precipitates such as arsenic sulfide, thus removing the arsenic impurities from the electronic-grade phosphoric acid. The arsenic sulfide precipitates generated by the reaction are sent to the arsenic salt collection tank 14 via the transfer pump 13; while the arsenic-removed electronic-grade phosphoric acid is sent to the ultrafiltration system 12 via the transfer pump 11 for ultrafiltration. After filtration through the ultrafiltration membrane, the small amount of arsenic salt and other impurities mixed in the electronic-grade phosphoric acid are removed, further improving the purity of the electronic-grade phosphoric acid. The arsenic salt filtered out by the ultrafiltration system 12 is still sent to the arsenic salt collection tank 14.

[0035] After being filtered through an ultrafiltration membrane, the electronic-grade phosphoric acid is directly fed into the phosphoric acid dilution tank 15. Ultrapure water is then injected into the phosphoric acid dilution tank 15 to adjust the electronic-grade phosphoric acid. The adjusted electronic-grade phosphoric acid is then injected into the four-stage filter 17 through the transfer pump 16 for a fourth filtration, further reducing the impurity content in the electronic-grade phosphoric acid to obtain semiconductor-grade electronic-grade phosphoric acid with a concentration of 85%.

[0036] The specific embodiments of this application have been described above, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An apparatus for producing electronic grade phosphoric acid, characterized by, The phosphoric acid production device comprises a preliminary impurity removal module, a phosphoric acid solution generation module, an arsenic removal module and a blending module connected in sequence; the preliminary impurity removal module comprises a yellow phosphorus tank, a primary filter and an impurity removal tank connected in sequence; the phosphoric acid solution generation module comprises a combustion tower; the arsenic removal module comprises an arsenic removal tank, an arsenic removal additive storage tank and an ultrafiltration system; the blending module comprises 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; and the electronic-grade phosphoric acid is discharged through a quaternary filter.

2. The apparatus for producing electronic grade phosphoric acid according to claim 1, wherein The combustion tower is provided with a cooler for cooling the refluxed phosphoric acid solution.

3. The apparatus for producing electronic grade phosphoric acid according to claim 1, wherein The arsenic removal module further comprises an arsenic salt collection tank, and the arsenic removal tank and the ultrafiltration system are connected with the arsenic salt collection tank respectively.

4. The apparatus for producing electronic grade phosphoric acid according to claim 1, wherein The number of filter elements of the primary filter comprises one of 3 elements and 5 elements; and the number of filter elements of the secondary filter, the tertiary filter and the quaternary filter comprises one of 3 elements, 5 elements and 12 elements.

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