Electronic-grade mixed acid recovery system

Abstract

The utility model discloses an electronic-grade mixed acid recovery system, which relates to the technical field of semiconductor manufacturing and comprises a purification tower, an entrainer is arranged in the purification tower, a purification tower inlet and a purification tower waste liquid outlet are arranged on a tower kettle of the purification tower, and a hydrofluoric acid separation port is arranged at the top of the purification tower. A purification tower side separation opening is formed in the side wall of a tower body of the purification tower, and an inlet of the purification tower is communicated with a waste acid liquid source to be recycled; the tower kettle of the light component removal tower is provided with a light component removal tower inlet, a light component removal tower kettle separation port and a light component removal tower waste liquid outlet, the tower top of the light component removal tower is provided with an entrainer breaking separation port, and the light component removal tower inlet is communicated with the tower side separation port of the purification tower; a heavy component removal tower inlet and a heavy component removal tower waste liquid outlet are formed in a tower kettle of the heavy component removal tower, a nitric acid separation opening is formed in the top of the heavy component removal tower, and the heavy component removal tower inlet is communicated with the separation opening of the tower kettle of the light component removal tower. The electronic-grade mixed acid recovery system disclosed by the embodiment of the utility model has the advantages of high recovery rate, high recovery purity, less hazardous waste emission and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductor manufacturing, and more particularly, to an electronic-grade mixed acid recovery system. Background Art

[0002] Electronic-grade polysilicon is one of the most basic and important raw materials for manufacturing semiconductor wafers and is known as the "grain" of the electronic information industry. In the post-treatment process of electronic-grade polysilicon production, a mixed acid is prepared by mixing high-purity nitric acid and hydrofluoric acid in a certain proportion to clean and etch silicon materials, remove surface impurities, and improve the purity of polysilicon. The waste acid after etching mainly contains nitric acid, hydrofluoric acid, and other impurities.

[0003] In the related art, the mixed acid recovery device can recover nitric acid and hydrofluoric acid in waste acid, but the obtained nitric acid and hydrofluoric acid have low purity, are difficult to reach the electronic grade, and cannot be remixed with new acid and returned to the process for use. Summary of the Utility Model

[0004] The utility model aims to solve at least one of the technical problems existing in the prior art. For this purpose, the utility model provides an electronic-grade mixed acid recovery system, which has the advantages of high recovery rate, high recovery purity, and less hazardous waste discharge.

[0005] To achieve the above object, according to an embodiment of the utility model, an electronic-grade mixed acid recovery system is provided, which includes: a purification tower, in which azeotropic breaking agent is provided, a purification tower inlet and a purification tower waste liquid outlet are provided on the bottom of the purification tower, a hydrofluoric acid separation port is provided on the top of the purification tower, a purification tower side separation port is provided on the side wall of the purification tower body, and the purification tower inlet is communicated with the waste acid liquid source to be recovered; a light component removal tower, a light component removal tower inlet, a light component removal tower bottom separation port, and a light component removal tower waste liquid outlet are provided on the bottom of the light component removal tower, azeotropic breaking agent separation port is provided on the top of the light component removal tower, and the light component removal tower inlet is communicated with the purification tower side separation port; a heavy component removal tower, a heavy component removal tower inlet and a heavy component removal tower waste liquid outlet are provided on the bottom of the heavy component removal tower, a nitric acid separation port is provided on the top of the heavy component removal tower, and the heavy component removal tower inlet is communicated with the light component removal tower bottom separation port.

[0006] The electronic-grade mixed acid recovery system according to the embodiment of the utility model has the advantages of high recovery rate, high recovery purity, and less hazardous waste discharge.

[0007] In addition, the electronic-grade mixed acid recovery system according to the above embodiment of the utility model may further have the following additional technical features:

[0008] According to an embodiment of the present utility model, the electronic-grade mixed acid recovery system is characterized in that it further includes: a hydrofluoric acid collection tank, which is communicated with the hydrofluoric acid separation port; a nitric acid collection tank, which is communicated with the nitric acid separation port; a waste liquid tank, which is respectively communicated with the waste liquid outlet of the purification tower, the waste liquid outlet of the light component removal tower, the waste liquid outlet of the heavy component removal tower, and the azeotrope-breaking agent separation port.

[0009] According to an embodiment of the present utility model, the electronic-grade mixed acid recovery system further includes a mixing device, and the mixing device is respectively communicated with the hydrofluoric acid collection tank and the nitric acid collection tank through a pumping device.

[0010] According to an embodiment of the present utility model, the electronic-grade mixed acid recovery system further includes a rapid settling tank, and the rapid settling tank is provided with a settling tank inlet and a settling tank outlet. The settling tank inlet is communicated with the waste acid liquid source to be recovered, and the settling tank outlet is communicated with the purification tower inlet.

[0011] According to an embodiment of the present utility model, the electronic-grade mixed acid recovery system further includes a filter, and sodium salts and potassium salts are provided in the filter. The filter is provided with a filter inlet, a filter outlet, and a solid waste outlet. The filter inlet is communicated with the settling tank outlet, and the filter outlet is communicated with the purification tower inlet.

[0012] According to an embodiment of the present utility model, the electronic-grade mixed acid recovery system further includes a buffer tank, and the buffer tank is provided with a buffer tank inlet and a buffer tank outlet. The buffer tank inlet is communicated with the filter outlet, and the buffer tank outlet is communicated with the purification tower inlet.

[0013] According to an embodiment of the present utility model, the electronic-grade mixed acid recovery system further includes a feed preheating device, and the feed preheating device is provided with a preheating inlet and a preheating outlet. The preheating inlet is communicated with the buffer tank outlet, and the preheating outlet is communicated with the purification tower inlet.

[0014] According to an embodiment of the present utility model, pumping devices are provided between the rapid settling tank and the filter and between the buffer tank and the feed preheating device.

[0015] According to an embodiment of the present utility model, there are two filters which are connected in parallel.

[0016] According to an embodiment of the present utility model, condensers are connected to the hydrofluoric acid separation port, the side separation port of the purification tower, the azeotrope-breaking agent separation port, and the nitric acid separation port.

[0017] Additional aspects and advantages of the present utility model will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present utility model. Brief Description of the Drawings

[0018] The above and / or additional aspects and advantages of the present utility model will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0019] Figure 1 is a schematic structural diagram of an electronic-grade mixed acid recovery system according to an embodiment of the present utility model.

[0020] Reference numerals: electronic-grade mixed acid recovery system 1, purification tower 10, purification tower inlet 11, purification tower waste liquid outlet 12, hydrofluoric acid separation port 13, purification tower side separation port 14, light component removal tower 20, light component removal tower inlet 21, light component removal tower bottom separation port 22, light component removal tower waste liquid outlet 23, azeotrope-breaking agent separation port 24, heavy component removal tower 30, heavy component removal tower inlet 31, heavy component removal tower waste liquid outlet 32, nitric acid separation port 33, hydrofluoric acid collection tank 40, nitric acid collection tank 50, waste liquid tank 60, rapid sedimentation tank 70, sedimentation tank inlet 71, sedimentation tank outlet 72, filter 80, filter inlet 81, filter outlet 82, solid waste outlet 83, buffer tank 90, feed preheating device 100, pumping device 110, condenser 120, reflux pipe 130, mixing device 140. Detailed Description of the Embodiments

[0021] Embodiments of the present utility model will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary only for explaining the present utility model and should not be construed as limiting the present utility model.

[0022] In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present utility model 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, and thus should not be construed as limiting the present utility model. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present utility model, unless otherwise specified, the meaning of "a plurality" is two or more.

[0023] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0024] The electronic grade mixed acid recovery system 1 according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0025] like Figure 1 As shown, the electronic grade mixed acid recovery system 1 according to an embodiment of the present invention includes a purification tower 10 , a light removal tower 20 and a heavy removal tower 30 .

[0026] A azeotrope breaker is provided in the purification tower 10, a purification tower inlet 11 and a purification tower waste liquid outlet 12 are provided on the bottom of the purification tower 10, a hydrofluoric acid separation port 13 is provided on the top of the purification tower 10, and a purification tower side separation port 14 is provided on the side wall of the tower body of the purification tower 10. The purification tower inlet 11 is connected to the source of the waste acid liquid to be recovered.

[0027] The bottom of the light-removal tower 20 is provided with a light-removal tower inlet 21, a light-removal tower bottom separation port 22 and a light-removal tower waste liquid outlet 23. The top of the light-removal tower 20 is provided with an azeotropic agent separation port 24. The light-removal tower inlet 21 is connected to the purification tower side separation port 14.

[0028] The bottom of the de-weighting tower 30 is provided with a de-weighting tower inlet 31 and a de-weighting tower waste liquid outlet 32 , and the top of the de-weighting tower 30 is provided with a nitric acid separation port 33 , and the de-weighting tower inlet 31 is connected to the separation port 22 of the bottom of the light removal tower.

[0029] Specifically, the purification tower 10, the light removal tower 20, and the heavy removal tower 30 each include a tower kettle and a tower body connected above the tower kettle. The materials in the tower kettle can be heated to vaporize and rise to the tower body, thereby separating materials with different boiling points.

[0030] The waste acid discharged from the pickling system enters the purification tower 10 through the purification tower inlet 11. Under the action of the azeotrope-breaking agent, the azeotropic phenomenon between hydrofluoric acid and nitric acid is broken. Hydrofluoric acid and water are separated through the hydrofluoric acid separation port 13 at the top of the tower. Nitric acid and the azeotrope-breaking agent are separated through the purification tower side separation port 14 on the side wall of the tower body. Metal impurities and the separated waste liquid are discharged through the purification tower waste liquid outlet 12. The material separated from the purification tower side separation port 14 of the purification tower 10 enters the light removal tower 20 through the light removal tower inlet 21. The azeotrope-breaking agent and water are removed through the azeotrope-breaking agent separation port 24 at the top of the tower. The material discharged from the light removal tower bottom separation port 22 enters the heavy removal tower 30 through the heavy removal tower inlet 31. Metal impurities and the separated waste liquid are discharged through the light removal tower waste liquid outlet 23. Electronic-grade nitric acid is separated through the nitric acid separation port 33 at the top of the heavy removal tower 30. Metal impurities and the separated waste liquid are discharged through the heavy removal tower waste liquid outlet 32.

[0031] According to the electronic-grade mixed acid recovery system 1 of the embodiment of the present invention, by setting the purification tower 10, the light removal tower 20, and the heavy removal tower 30, compared with the mixed acid recovery system in the related art, after the waste acid to be recovered changes the gas-liquid equilibrium relationship of the system through the azeotrope-breaking agent, high-purity electronic-grade hydrofluoric acid can be purified and separated. Then, the azeotrope-breaking agent is separated through heavy removal, and finally, high-purity electronic-grade nitric acid is separated through light removal. The metal impurity content in the waste acid can be reduced to below the ppb (part per billion) level. The recovery rate of hydrofluoric acid is greater than 80%, the concentration of the recovered hydrofluoric acid reaches 15%, the recovery rate of nitric acid is greater than 90%, and the concentration of the recovered nitric acid reaches more than 68%. Thus, not only can the recovery utilization rate of nitric acid and hydrofluoric acid in the waste acid be improved, the purity of the recovered nitric acid and hydrofluoric acid be increased, so that the recovered nitric acid and hydrofluoric acid can reach the electronic grade for easy reuse in the process, avoiding the waste of nitric acid and hydrofluoric acid and reducing the production cost, but also the emissions of hydrofluoric acid and nitric acid in the waste liquid can be reduced, the hazardous waste emissions can be reduced, and the environmental pollution can be reduced, making it more environmentally friendly.

[0032] Therefore, the electronic-grade mixed acid recovery system 1 according to the embodiment of the present invention has the advantages of high recovery rate, high recovery purity, and less hazardous waste emissions.

[0033] Next, the electronic-grade mixed acid recovery system 1 according to the specific embodiment of the present invention will be described with reference to the accompanying drawings.

[0034] In some specific embodiments of the present invention, as Figure 1 shown, the electronic-grade mixed acid recovery system 1 according to the embodiment of the present invention includes a purification tower 10, a light removal tower 20, and a heavy removal tower 30.

[0035] Specifically, as Figure 1As shown, the electronic-grade mixed acid recovery system 1 further includes a hydrofluoric acid collection tank 40, a nitric acid collection tank 50, and a waste liquid tank 60. The hydrofluoric acid collection tank 40 is in communication with the hydrofluoric acid separation port 13. The nitric acid collection tank 50 is in communication with the nitric acid separation port 33. The waste liquid tank 60 is respectively in communication with the purification tower waste liquid outlet 12, the light removal tower waste liquid outlet 23, the heavy removal tower waste liquid outlet 32, and the azeotropy breaker separation port 24. In this way, the separated nitric acid, hydrofluoric acid, and waste liquid can be collected separately by using the storage tanks, which facilitates centralized treatment of the waste liquid and facilitates recycling of the separated hydrofluoric acid and nitric acid.

[0036] More specifically, if Figure 1 As shown, the electronic-grade mixed acid recovery system 1 further includes a mixing device 140, which is connected to the hydrofluoric acid collection tank 40 and the nitric acid collection tank 50 via a pumping device 110. In this way, the mixing device 140 can be used to mix and distribute the recovered nitric acid and hydrofluoric acid with the new acid for return to the process for reuse.

[0037] Advantageously, as Figure 1 As shown, the electronic-grade mixed acid recovery system 1 also includes a rapid settling tank 70, which is provided with a settling tank inlet 71 and a settling tank outlet 72. The settling tank inlet 71 is connected to the source of the waste acid to be recovered, and the settling tank outlet 72 is connected to the purification tower inlet 11. This allows the waste acid to undergo preliminary settling in the rapid settling tank 70 before entering the purification tower 10, separating some impurities through sedimentation and preventing impurities from affecting subsequent separation processes.

[0038] More advantageously, if Figure 1 As shown, the electronic-grade mixed acid recovery system 1 further includes a filter 80, which contains sodium salt and potassium salt. Filter 80 is provided with a filter inlet 81, a filter outlet 82, and a solid waste outlet 83. Filter inlet 81 is connected to the sedimentation tank outlet 72, and filter outlet 82 is connected to the purification tower inlet 11. This allows the settled waste acid to be filtered through filter 80, and the sodium salt and potassium salt are used to remove silicofluoric acid from the mixed acid, facilitating separation in subsequent steps.

[0039] Figure 1 FIG. 1 shows an electronic grade mixed acid recovery system 1 according to some examples of the present invention. Figure 1 As shown, the electronic-grade mixed acid recovery system 1 further includes a buffer tank 90 having a buffer tank inlet and a buffer tank outlet. The buffer tank inlet is connected to the filter outlet 82, and the buffer tank outlet is connected to the purification tower inlet 11. In this way, the buffer tank 90 can be used to buffer and store the mixed acid after preliminary sedimentation and filtration, facilitating separation in subsequent steps and allowing the separation process to proceed continuously.

[0040] Advantageously, as Figure 1As shown, the electronic-grade mixed acid recovery system 1 also includes a feed preheating device 100, which is provided with a preheating inlet and a preheating outlet. The preheating inlet is connected to the outlet of the buffer tank, and the preheating outlet is connected to the purification tower inlet 11. This preheats the mixed acid after settling and filtration, allowing it to quickly reach its boiling point upon entering the purification tower 10, shortening the heating process within the purification tower 10 and improving separation efficiency.

[0041] Specifically, if Figure 1 As shown, a pumping device 110 is provided between the rapid settling tank 70 and the filter 80 and between the buffer tank 90 and the feed preheating device 100. In this way, the pumping device 110 can be used to provide power for the flow of the acid solution.

[0042] Specifically, each pumping device 110 includes two liquid pumps connected in parallel, one of the two liquid pumps is in operation to achieve pumping and the other is used as a standby, so that the separation process can be carried out continuously.

[0043] More advantageously, if Figure 1 Shown, filter 80 is two and is connected in parallel. Like this can make two filters 80 one filter and another as standby, so that the filtering process is carried out continuously.

[0044] More specifically, if Figure 1 As shown, the hydrofluoric acid separation port 13, the purification tower side separation port 14, the azeotrope breaker separation port 24 and the nitric acid separation port 33 are all connected to a condenser 120. This allows the separated gas phase to be quickly condensed into a liquid phase for easy transportation and storage.

[0045] Specifically, if Figure 1 As shown, a reflux pipe 130 is provided between the outlet of the pumping device 110 at the outlet of the rapid settling tank 70 and the rapid settling tank 70, between the outlet of the condenser 120 and the corresponding tower body, between the pumping device 110 at the outlet of the hydrofluoric acid collection tank 40 and the hydrofluoric acid collection tank 40, and between the pumping device 110 at the outlet of the nitric acid collection tank 50 and the nitric acid collection tank 50. This facilitates the reflux of the liquid.

[0046] Other structures and operations of the electronic-grade mixed acid recovery system 1 according to the embodiment of the present invention are known to those skilled in the art and will not be described in detail here.

[0047] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative use of the above terms does not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0048] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and purpose of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An electronic-grade mixed acid recovery system, characterized in that, Comprising: A purification column, in which an azeotrope breaker is provided. A purification column inlet and a purification column waste liquid outlet are provided on the bottom of the purification column. A hydrofluoric acid separation port is provided at the top of the purification column. A purification column side separation port is provided on the side wall of the column body of the purification column. The purification column inlet is communicated with a waste acid liquid source to be recycled. A light component removal column, on the bottom of which a light component removal column inlet, a light component removal column bottom separation port and a light component removal column waste liquid outlet are provided. Azeotrope breaker separation port is provided at the top of the light component removal column. The light component removal column inlet is communicated with the purification column side separation port. A heavy component removal column, on the bottom of which a heavy component removal column inlet and a heavy component removal column waste liquid outlet are provided. A nitric acid separation port is provided at the top of the heavy component removal column. The heavy component removal column inlet is communicated with the light component removal column bottom separation port.

2. The electronic-grade mixed acid recovery system according to claim 1, wherein Further comprising: A hydrofluoric acid collection tank, which is communicated with the hydrofluoric acid separation port. A nitric acid collection tank, which is communicated with the nitric acid separation port. A waste liquid tank, which is respectively communicated with the purification column waste liquid outlet, the light component removal column waste liquid outlet, the heavy component removal column waste liquid outlet and the azeotrope breaker separation port.

3. The electronic-grade mixed acid recovery system according to claim 2, wherein Further comprising a mixing device, which is respectively communicated with the hydrofluoric acid collection tank and the nitric acid collection tank through a pumping device.

4. The electronic-grade mixed acid recovery system according to claim 1, wherein Further comprising a rapid settling tank, on which a settling tank inlet and a settling tank outlet are provided. The settling tank inlet is communicated with the waste acid liquid source to be recycled. The settling tank outlet is communicated with the purification column inlet.

5. The electronic-grade mixed acid recovery system according to claim 4, wherein Further comprising a filter, in which sodium salts and potassium salts are provided. A filter inlet, a filter outlet and a solid waste outlet are provided on the filter. The filter inlet is communicated with the settling tank outlet. The filter outlet is communicated with the purification column inlet.

6. The electronic-grade mixed acid recovery system according to claim 5, wherein, Further comprising a buffer tank, on which a buffer tank inlet and a buffer tank outlet are provided. The buffer tank inlet is communicated with the filter outlet. The buffer tank outlet is communicated with the purification column inlet.

7. The electronic-grade mixed acid recovery system according to claim 6, characterized in that, Further comprising a feed preheating device, on which a preheating inlet and a preheating outlet are provided. The preheating inlet is communicated with the buffer tank outlet. The preheating outlet is communicated with the purification column inlet.

8. The electronic-grade mixed acid recovery system according to claim 7, wherein, Pumping devices are provided between the rapid settling tank and the filter and between the buffer tank and the feed preheating device.

9. The electronic-grade mixed acid recovery system according to claim 5, wherein There are two filters which are connected in parallel.

10. The electronic-grade mixed acid recovery system according to claim 1, wherein Condensers are connected to the hydrofluoric acid separation port, the purification column side separation port, the azeotrope breaker separation port and the nitric acid separation port.

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