An electronic grade hydrofluoric acid recovery device

Abstract

This invention discloses an electronic-grade hydrofluoric acid recovery device, relating to the field of waste liquid recovery technology. It includes two horizontally aligned supports, each with a through-hole sized to match a drift tube. A drift tube is fitted inside one of the supports, and the drift tube has a circular hole sized to match a dialysis membrane. Several focusing rings are attached to the inside of the drift tube. By connecting the multiple focusing rings to a power source, an electric field is formed between them. The focusing rings at both ends are the anode and cathode of the electric field. As argon gas is injected into the center of the focusing rings through a gas injection pipe, ions in the waste acid migrate under the influence of the electric field and the damping effect of the reverse gas flow. Therefore, ion migration occurs in the waste acid. The migration rate of ions in the waste acid is affected by the ion's inherent properties, i.e., its radius. Ions with smaller ionic radii are more easily hindered by solvent molecules in the solution, thus exhibiting a lower migration rate.

Description

Technical Field

[0001] This invention relates to the field of waste liquid technology, specifically to an electronic-grade hydrofluoric acid recovery device. Background Technology

[0002] Electronic-grade hydrofluoric acid is primarily used as a cleaning agent and etching agent in industries such as photovoltaics and integrated circuits. It is a key auxiliary material in these industries, accounting for over 70% of the total electronic-grade hydrofluoric acid usage in integrated circuits and large-scale integrated circuits. The production of electronic-grade hydrofluoric acid mainly utilizes a combination of physical and chemical methods, further purifying it by distillation based on the different boiling points of various substances in hydrogen fluoride. However, when electronic-grade hydrofluoric acid is used to etch integrated circuits, the resulting waste liquid contains metal ions in addition to hydrofluoric acid. Current treatment processes often involve incinerating the waste acid, which not only wastes resources but may also pollute the environment. Furthermore, while some existing technologies mention using nanofiltration membranes (PES membranes) to treat the waste acid, these methods also involve the use of PES membranes for waste acid recovery. In these cases, the concentration of free hydrofluoric acid ions in the waste acid gradually increases over time during nanofiltration. However, this increased concentration of free hydrofluoric acid ions negatively impacts the interception rate of the nanofiltration membrane. Correspondingly, during nanofiltration, the concentration of metal ions in the waste acid increases. This increased concentration leads to a decrease in the nanofiltration membrane's metal ion interception rate, inevitably resulting in acid imbalance and efflux, thus affecting the separation and recovery of waste acid. Furthermore, the nanofiltration membrane's metal ion interception rate is affected by the concentration of solvents such as hydrofluoric acid. If the nanofiltration membrane's metal ion interception rate is low, a large amount of metal ions may remain in the recovered hydrofluoric acid solution. Excessive metal ions affect the concentration and purity of the recovered hydrofluoric acid, requiring significant resources to remove these metal ions during subsequent purification. To address these issues, we propose an electronic-grade hydrofluoric acid recovery device that uses a nanofiltration membrane to recover waste acid after etching integrated circuits, prevents excessive metal ion concentration in the waste acid solution from efflux during nanofiltration, and avoids excessive hydrofluoric acid ion concentration in the waste acid solution from reducing the nanofiltration membrane's metal ion interception rate. Summary of the Invention

[0003] (a) Technical problem to be solved: In view of the above, and in view of the shortcomings of the prior art, the present invention provides an electronic-grade hydrofluoric acid recovery device to solve the problems mentioned in the background art.

[0004] (II) Technical Solution: To achieve the above-mentioned objectives of recovering waste mixed acid after etching integrated circuits using nanofiltration membranes, preventing excessive metal ion concentration in the waste acid solution during nanofiltration process from causing leakage from the nanofiltration membrane, and avoiding excessive hydrofluoric acid ion concentration in the waste acid solution from reducing the interception rate of metal ions by the nanofiltration membrane, the present invention provides the following technical solution: An electronic-grade hydrofluoric acid recovery device, comprising two horizontally aligned supports, each support having a through hole with a size adapted to a drift tube, one of the supports having a drift tube sleeved inside, the drift tube having a circular hole with a size adapted to a dialysis membrane, and several focusing rings attached to the inside of the drift tube, the focusing rings being circular in shape, each focusing ring being connected to the current output terminal of an external power storage device, the distance between any two adjacent focusing rings being equal, and a drift tube being attached between any two adjacent focusing rings. The inner wall has a dialysis membrane, which is an anion homogeneous membrane. A gas injection tube is connected through the top of the drift tube at the end away from the focusing ring. The gas injection tube is connected to the gas output port of an external inert gas storage device. The end of the gas injection tube inside the drift tube coincides with the center point of the focusing ring. The device also includes a limiting block that is snapped onto the outside of the drift tube on one side. The limiting block has a through groove with a size adapted to the precipitation chamber inside. The top of the limiting block has a through hole with a size adapted to the input port. The top of the limiting block is connected through the input port. A precipitation chamber is set at the end of the input port that is inside the limiting block. A through groove with a size adapted to the locking block is set at the bottom of the precipitation chamber. The precipitation chamber is attached to the inner wall of the input port. A locking block is set at the bottom of the input port and the precipitation chamber. Two axisymmetric connectors are respectively hinged to the two ends of the bottom of the locking block. A nanofiltration membrane is set on the side of the limiting block away from the drift tube.

[0005] Preferably, the card block has a through groove that fits into the input port and the bottom of the sedimentation chamber, and the end of each connector away from the card block is fastened to the outer wall of the input port.

[0006] Preferably, the filter chamber is engaged with the side of the limiting block away from the drift tube. The top of the filter chamber has a circular hole with a size that matches the positioning tube. The top of the filter chamber is connected through the positioning tube. The outside of the positioning tube is connected through the liquid input tube. The inside of the positioning tube is provided with a piston that fits the inner wall of the positioning tube. The size of the piston matches the through groove opened inside the positioning tube.

[0007] Preferably, a round rod is fixedly connected inside the piston one, the length of which is adapted to the distance between piston one and piston two. A collection groove located directly below the positioning tube one is fixedly connected to the outer side of the middle position of the round rod, and the material around the collection groove is a transparent film.

[0008] Preferably, the nanofiltration membrane is disposed at the connection between the limiting block and the filter chamber, and the nanofiltration membrane is fitted to the inner wall of the filter chamber.

[0009] Preferably, a liquid output pipe is connected through the outer side of the second positioning tube.

[0010] Preferably, the end of the round rod away from the piston one is fixedly connected to the piston two, and the bottom of the piston two is fitted with a support member whose other end is fixedly connected to the bottom end of the inner wall of the positioning tube two.

[0011] Preferably, the inner wall of the second positioning tube is fitted with a support ring located on the outer side below the second piston. The support ring is penetrated by a support member at one end away from the inner wall of the second positioning tube. Two axially symmetrical hydraulic rods are fixedly connected to both sides of the bottom of the support ring. The end of each hydraulic rod away from the support ring is fixedly connected to a limiting member.

[0012] Preferably, the limiting member is fixedly connected to the inner wall of the positioning tube two.

[0013] (III) Beneficial Effects: Compared with the prior art, the present invention provides an electronic-grade hydrofluoric acid recovery device with the following beneficial effects: 1. The waste acid after etching integrated circuit boards is filtered through a nanofiltration membrane. The pore size of the nanofiltration membrane is about one to two nanometers, which can separate substances with relatively small molecular weight from the solvent. When in use, two pressure environments need to be set on both sides of the nanofiltration membrane to form a pressure difference between the liquids (waste acid and ultrapure water) on both sides of the nanofiltration membrane. Since the nanofiltration membrane itself is a charged membrane, it can perform electro-adsorption and separate hydrofluoric acid, metal ions and other impurities in the waste acid. This avoids the problem of incinerating the waste acid after use, which wastes resources and may pollute the environment. 2. By connecting multiple annular focusing rings to a power source, an electric field is formed between the rings. The focusing rings at both ends are the anode and cathode of the electric field. As argon gas is supplied to the center of the annular focusing rings through the gas injection pipe, ions in the waste acid migrate under the influence of the electric field and the damping effect of the reverse gas. Therefore, ion migration occurs in the waste acid. The migration rate of ions in the waste acid is affected by the nature of the ions, i.e., their radius. Ions with smaller ionic radii are more easily hindered by solvent molecules in the solution, and therefore have a lower migration rate. Thus, the migration rate of hydrofluoric acid ions in the waste acid is higher than that of metal ions. Metal ions reach the nanofiltration membrane under the influence of the electric field, thereby initially separating hydrofluoric acid ions from metal ions in the waste acid solution, which facilitates the subsequent collection of high-purity hydrogen fluoride. 3. Under the influence of an electric field, metal ions in the waste acid first reach the nanofiltration membrane and come into contact with the heavy metal scavenging agent. Due to the strong chelating properties of the heavy metal scavenging agent, it can strongly complex with the metal ions in the waste acid, precipitating them and forming flocs. After the waste acid filtration is completed, the flocculent precipitate can be removed, the device can be cleaned, and the content of metal ions in the waste acid after precipitation will be reduced. As the waste acid is filtered by the nanofiltration membrane, the concentration of metal ions on one side of the nanofiltration membrane will increase as the nanofiltration process proceeds. High concentrations of metal ions will affect the acid imbalance on both sides of the nanofiltration membrane, causing the hydrofluoric acid after nanofiltration to be discharged. Excessively high metal ion concentrations will also affect the interception rate of metal ions in the waste acid by the nanofiltration membrane, resulting in a large number of metal ions mixed in the hydrofluoric acid solution after nanofiltration. Reducing the metal ion concentration can increase the purity of the hydrofluoric acid after nanofiltration. 4. By setting high-pressure and low-pressure environments at both ends of the nanofiltration membrane, the waste acid is under high pressure, while the low-pressure side is filled with ultrapure water. Under the influence of pressure difference and liquid concentration difference, hydrofluoric acid ions and metal ions in the waste acid will move towards the ultrapure water side. Hydrofluoric acid ions will pass through the nanofiltration membrane into the ultrapure water, thereby recovering and reusing hydrofluoric acid ions in the waste acid.5. Hydrofluoric acid ions are absorbed by ultrapure water placed on the other side of the nanofiltration membrane. As the hydrofluoric acid ions shift, the concentration of hydrofluoric acid ions inside the ultrapure water gradually increases. Excessive ion concentration can affect the nanofiltration membrane's interception rate of metal ions. Therefore, as hydrofluoric acid ions gradually integrate into the ultrapure water, the molecular weight of the ultrapure water gradually increases. When the weight reaches a set value, the ultrapure water containing hydrofluoric acid ions can be collected at the bottom of the device. Simultaneously, ultrapure water is re-injected into the device from the top to reduce the concentration of hydrofluoric acid ions inside. This prevents the ultrapure water obtained after nanofiltration from having an excessively high concentration of hydrofluoric acid ions, which would affect the nanofiltration membrane's interception rate of metal ions. Furthermore, when the concentration of hydrofluoric acid ions in the ultrapure water is too high, the concentration difference between it and the waste acid decreases, affecting the speed at which hydrofluoric acid ions pass through the nanofiltration membrane. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0015] Figure 2 This is a schematic diagram of the connection relationship at the limiting block of the present invention.

[0016] Figure 3 This is a schematic diagram of the internal structure of the drift tube of the present invention.

[0017] Figure 4 This is a schematic diagram showing the positional relationship of the gas injection pipe in this invention.

[0018] Figure 5 This is a cross-sectional view of the inside of the limiting block of the present invention.

[0019] Figure 6 This is a cross-sectional schematic diagram of the interior of the filter chamber of the present invention.

[0020] Figure 7 For the present invention Figure 6 Enlarged view of the structure at point A in the middle.

[0021] Figure 8 This is a cross-sectional schematic diagram of the interior of the positioning tube II of the present invention.

[0022] Figure 9 This is a schematic diagram showing the positional relationship of the two pistons in this invention.

[0023] Figure 10 For the present invention Figure 9 Enlarged view of the structure at point B in the middle.

[0024] In the diagram: 101, support; 102, drift tube; 103, focusing ring; 104, dialysis membrane; 105, gas injection tube; limiting block; 202, inlet; 203, sedimentation chamber; 204, locking block; 205, connector; 206, nanofiltration membrane; filter chamber; 302, positioning tube one; 303, liquid inlet tube; 304, piston one; 305, round rod; 306, collection tank; 401, positioning tube two; 402, liquid outlet tube; 403, piston two; 404, support; 405, support ring; 406, hydraulic rod; 407, limiting component. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1: Please refer to Figures 1 to 5An electronic-grade hydrofluoric acid recovery device includes two horizontally aligned supports 101. Each support 101 has a through-hole with a size adapted to a drift tube 102. A drift tube 102 is fitted inside one of the supports 101. The drift tube 102 has a circular hole with a size adapted to a dialysis membrane 104. Several focusing rings 103 are attached to the inside of the drift tube 102. Each focusing ring 103 is annular in shape and connected to the current output terminal of an external power storage device. Every two adjacent focusing rings... The focusing rings 103 are equidistant from each other. Between every two adjacent focusing rings 103, a dialysis membrane 104 is provided, conforming to the inner wall of the drift tube 102. The dialysis membrane 104 is an anion homogeneous membrane. A gas injection tube 105 is connected through the top of the drift tube 102 at the end furthest from the focusing rings 103. The gas injection tube 105 is connected to the gas output port of an external inert gas storage device. The end of the gas injection tube 105 inside the drift tube 102 coincides with the center point of the focusing rings 103, and also includes a side that is snapped into the drift tube 102. The outer limiting block 201 has a through groove inside that matches the size of the sedimentation chamber 203. The top of the limiting block 201 has a through hole that matches the size of the input port 202. The input port 202 is connected through the top of the limiting block 201. A sedimentation chamber 203 is located at one end of the input port 202, which extends through the interior of the limiting block 201. The bottom of the sedimentation chamber 203 has a through groove that matches the size of the locking block 204. The sedimentation chamber 203 fits against the inner wall of the input port 202. The input port 202 and the sedimentation chamber 203... A locking block 204 is provided at the bottom of the container. The locking block 204 fits into the bottom of the inlet 202 and the sedimentation chamber 203 and has a through groove. Two axisymmetric connectors 205 are hinged to the two ends of the bottom of the locking block 204. The end of each connector 205 away from the locking block 204 is fastened to the outer wall of the inlet 202. A nanofiltration membrane 206 is provided on the side of the limiting block 201 away from the drift tube 102. The nanofiltration membrane 206 is located at the connection between the limiting block 201 and the filter chamber 301 and fits into the inner wall of the filter chamber 301.

[0027] The effects achieved by this embodiment are as follows: Compared with the prior art, the waste acid is filtered by using a nanofiltration membrane 206, thereby performing nanofiltration on the waste acid after etching integrated circuits. By applying an electric field to the waste acid, metal ions and hydrofluoric acid ions in the waste acid undergo ion migration. Due to the ionic radius, the migration rate of metal ions is higher than that of hydrofluoric acid ions. The metal ions are squeezed out with the heavy metal capture agent first, forming flocculent compounds, which reduces the concentration of metal ions in the waste acid. This prevents the concentration of metal ions from being too high during the nanofiltration process, which would lead to acid imbalance at both ends of the nanofiltration membrane 206 and cause the nanofiltration hydrofluoric acid to be discharged. At the same time, the reduced concentration of metal ions does not affect the interception rate of metal ions by the nanofiltration membrane 206, thus avoiding the presence of a large number of metal ions in the hydrofluoric acid solution after nanofiltration, which would reduce the purity of the hydrofluoric acid.

[0028] Example 2: Please refer to Figure 1 , Figure 2 and Figures 5 to 9 An electronic-grade hydrofluoric acid recovery device includes a filter chamber 301, which is engaged with a limiting block 201 on the side away from the drift tube 102. The top of the filter chamber 301 has a circular hole with a size adapted to the positioning tube 302. The positioning tube 302 is connected through the top of the filter chamber 301. A liquid input tube 303 is connected through the outside of the positioning tube 302. A piston 304 is provided inside the positioning tube 302 and fits against the inner wall of the positioning tube 302. The size of the piston 304 is adapted to the through groove opened inside the positioning tube 302. A round rod 305 is fixedly connected inside the piston 304. The length of the round rod 305 is adapted to the distance between the piston 304 and the piston 403. A collection tank 306 located directly below the positioning tube 302 is fixedly connected to the outer side of the middle position of the round rod 305. The material around the collection tank 306 is a transparent film.

[0029] The effects achieved by this embodiment are as follows: Compared with the prior art, as the amount of hydrofluoric acid ions mixed in the ultrapure water increases, the mass and concentration of the mixed solution will also increase. Excessive concentration will affect the interception rate of metal ions by the nanofiltration membrane 206 and reduce the concentration difference of the solution at both ends of the nanofiltration membrane 206, thus affecting the passage of ions through the nanofiltration membrane 206. When the concentration of the mixed solution is too high, ultrapure water is injected into the mixed solution to dilute the mixed solution and reduce its concentration. At the same time, the concentration difference between waste acid and ultrapure water can be adjusted to avoid affecting the nanofiltration of hydrofluoric acid in the waste acid.

[0030] Example 3: Please refer to Figures 8 to 10 An electronic-grade hydrofluoric acid recovery device includes a second positioning tube 401, which penetrates the bottom of a filter chamber 301. A liquid output tube 402 is connected to the outer side of the second positioning tube 401. A piston 403 is fixedly connected to one end of a round rod 305 away from a piston 304. A support member 404 is attached to the middle of the bottom of the piston 403, and its other end is fixedly connected to the bottom of the inner wall of the second positioning tube 401. A support ring 405 located below and outside the piston 403 is attached to the inner wall of the second positioning tube 401. The support ring 405 is penetrated by one end of the support member 404 away from the inner wall of the second positioning tube 401. Two axially symmetrical hydraulic rods 406 are fixedly connected to both sides of the bottom of the support ring 405. The end of each hydraulic rod 406 away from the support ring 405 is fixedly connected to a limiting member 407, which is fixedly connected to the inner wall of the second positioning tube 401.

[0031] The effects achieved by this embodiment are as follows: Compared with the prior art, when the mass of hydrofluoric acid ions mixed in the ultrapure water reaches the upper limit of the support weight of the hydraulic rod 406, the ultrapure water mixed with hydrofluoric acid will be discharged and collected, reducing the mass of ultrapure water inside the device. After the new ultrapure water is mixed in, the concentration difference between the mixed solution inside the device and the waste acid is adjusted, avoiding affecting the nanofiltration of hydrofluoric acid ions in the waste acid and facilitating the collection of ultrapure water mixed with hydrofluoric acid ions after nanofiltration.

[0032] The overall working process and principle of Embodiments 1 to 3 are as follows: First, the waste hydrofluoric acid after etching the integrated circuit is introduced from one end of the drift tube 102. An external high-pressure pump adjusts the internal air pressure of the drift tube 102 to a high-pressure environment, making the air pressure inside the drift tube 102 on both sides of the nanofiltration membrane 206 higher than the air pressure inside the filter chamber 301, creating a pressure difference. Then, ultrapure water is injected into the filter chamber 301 through the liquid input pipe 303. The ultrapure water enters the filter chamber 301 through the positioning pipe 302. After entering the filter chamber 301, it first falls into the collection tank 306. As ultrapure water continues to be injected, the weight of the collection tank 306 gradually increases, causing the round rod 305 fixedly connected to it to move downwards. This causes the piston 304, originally located above the positioning pipe 302 and the liquid input pipe 303, to descend. As the weight of the ultrapure water injected into the filter chamber 301 increases, it gradually blocks the flow. When the ultrapure water fills the filter chamber 301, the piston 304 will block the connection between the positioning tube 302 and the liquid input tube 303, preventing the liquid input tube 303 from continuing to inject ultrapure water into the filter chamber 301. At this time, the piston 403, which moves synchronously with the downward movement of the round rod 305, will also move downward from the position above the positioning tube 401 and the liquid output tube 402, squeezing the support member 404 that is attached to the center of the piston 403, causing the support member 404 to contract. The piston 403 will block the liquid output tube 402 at the same time as the piston 304 blocks the liquid input tube 303. At this time, the bottom of the piston 403 contacts the top of the support ring 405 located on the outer side of the bottom of the piston 403. The support ring 405 assists the support member 404 in fixing the position of the piston 403, thereby facilitating the injection of ultrapure water into the device.Then, the external argon storage device is turned on, and argon gas is injected into the drift tube 102 through the gas injection pipe 105 connected to the gas output end of the external argon storage device. At this time, the external power supply is turned on, and the focusing ring 103 connected to the output end of the external power supply is energized to form an electric field. The focusing rings 103 at both ends become the anode and cathode in the electric field. Hydrogen ions and metal ions in the waste acid will undergo ion migration under the action of the electric field. Inside the drift tube 102, they move in the opposite direction of the argon gas flow. After passing through one focusing ring 103, the hydrogen ions and metal ions... Then, the ions pass through a dialysis membrane 104, which is a reverse osmosis membrane to prevent them from migrating in the opposite direction during migration. The ion mobility can be obtained by calculating the time it takes for the ions to pass through the drift tube 102. The ion mobility is related to the collision cross-section between the ion and the electric field. Generally speaking, the smaller the cross-sectional area and the higher the charge, the faster the migration speed. The cross-sectional area refers to the contact area between the ion and the electric field, that is, the smaller the ion radius, the greater the speed of movement in the electric field. Since the ion migration rate is affected by the ion radius, in waste acid, free hydrofluoric acid will be presented as hydrogen ions, which are the main group... Comparing the radii of elemental ions requires considering two factors: 1. The more electron shells an ion has, the larger its radius; 2. The more positive charge an ion carries, the smaller its radius, and the more negative charge it carries, the larger its radius. The first factor has a much greater impact than the second. Since hydrogen ions have only one electron shell, while metal ions in waste acid, such as aluminum and copper ions (aluminum ions have three electron shells, and copper ions have four), will have a faster velocity for hydrogen ions than for metal ions in an electric field. The larger ionic radius of metal ions will result in a faster velocity difference between hydrogen ions and metal ions in the waste acid. Since the concentration of metal ions is less than that of hydrogen ions, the metal ions in the waste acid will lag behind the hydrogen ions. After the hydrogen ions move through the precipitation chamber 203 to the nanofiltration membrane 206, the metal ions will come into contact with the heavy metal capture agent poured into the precipitation chamber 203 through the inlet 202 and form flocculent precipitate, thereby removing the metal ions contained in the waste acid. This prevents the concentration of metal ions from increasing as the nanofiltration process proceeds, and prevents the metal ions from accumulating around the nanofiltration membrane 206, affecting the interception rate of metal ions by the nanofiltration membrane 206, resulting in a large number of metal ions in the hydrofluoric acid solution collected after nanofiltration.Hydrofluoric acid ions in the waste acid enter the precipitation chamber 203 before the metal ions and exit through the permeation membranes on both sides of the precipitation chamber 203, migrating to a position close to the nanofiltration membrane 206. Under the influence of pressure and concentration differences, the hydrofluoric acid ions in the waste acid enter the ultrapure water from the waste acid end of the nanofiltration membrane 206, collecting the hydrogen ions from the waste acid into the ultrapure water. As the nanofiltration process proceeds, the concentration difference between the waste acid and ultrapure water on both sides of the nanofiltration membrane 206 decreases, and the increased concentration of the ultrapure water also affects the metal ion rejection rate of the nanofiltration membrane 206. Because hydrogen ions are continuously introduced into the ultrapure water during the nanofiltration process, the mass of ultrapure water with hydrogen ions is greater than that of ultrapure water without hydrogen ions for the same volume. At this point, the weight of the ultrapure water will be greater than the supporting force of the support ring 405 and the hydraulic rod 406. Therefore, the piston 2 403 will continue to descend along the inner wall of the positioning tube 2 401, opening the connection between the positioning tube 2 401 and the liquid output tube 402. The ultrapure water mixed with hydrogen ions inside the filter chamber 301 will leave the filter chamber 301 through the liquid output tube 402, thereby collecting the ultrapure water mixed with hydrogen ions. As the piston 2 403 descends, the piston 1 304, which is fixedly connected to the piston 2 403 through the round rod 305, will also move downward. The positioning tube 1 302 and the liquid input tube 303, which are blocked by the piston 1 304, will open. The ultrapure water will enter the filter chamber 301 through the round hole opened in the middle of the piston 1 304.

[0033] As the ultrapure water containing hydrogen ions flows out of the filter chamber 301 and new ultrapure water is injected, the concentration and mass of the liquid inside the filter chamber 301 decrease. Therefore, piston 2 403 rises under the action of hydraulic rod 406, support ring 405, and support member 404, filling the filter chamber 301 with new ultrapure water and sealing the connection between positioning tube 2 401 and liquid output tube 402. At this time, piston 1 304 also rises, sealing the connection between positioning tube 1 302 and liquid input tube 303. By injecting new ultrapure water into the ultrapure water containing hydrofluoric acid, the liquid concentration is reduced, and the ultrapure water containing hydrofluoric acid is further purified. Pure water is collected, which avoids the high concentration of ultrapure water mixed with hydrofluoric acid affecting the interception rate of metal ions in waste acid by nanofiltration membrane 206. After nanofiltration is completed, the connector 205 fastened to the outside of the limiting block 201 is removed, so that the locking block 204 connected by the connector 205 and the limiting block 201 are separated. At this time, the staff can hold the bottom of the locking block 204 and remove the locking block 204 from the bottom of the limiting block 201. Since the locking block 204 fits the through groove opened at the bottom of the limiting block 201 and the sedimentation chamber 203, removing the locking block 204 can remove the flocculent precipitate generated by the reaction of metal ions and heavy metal capture agent inside the sedimentation chamber 203, and the device can be cleaned.

[0034] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An electronic-grade hydrofluoric acid recovery device, comprising two horizontally aligned supports (101), characterized in that: One of the supports (101) has a drift tube (102) sleeved inside. Several focusing rings (103) are attached to the inside of the drift tube (102). The distance between any two adjacent focusing rings (103) is equal. A dialysis membrane (104) is provided between each two adjacent focusing rings (103) and adheres to the inner wall of the drift tube (102). A gas injection tube (105) is connected through the top of the drift tube (102) away from the focusing rings (103). The end of the gas injection tube (105) inside the drift tube (102) coincides with the center point of the focusing rings (103). It also includes a side clamp. A limiting block (201) is attached to the outside of the drift tube (102). An input port (202) is connected through the top of the limiting block (201). A sedimentation chamber (203) is provided at one end of the input port (202) inside the limiting block (201). The sedimentation chamber (203) fits against the inner wall of the input port (202). A locking block (204) is provided at the bottom of the input port (202) and the sedimentation chamber (203). Two axisymmetric connectors (205) are respectively hinged at both ends of the bottom of the locking block (204). A nanofiltration membrane (206) is provided on the side of the limiting block (201) away from the drift tube (102). The card block (204) is fitted with the bottom of the inlet (202) and the sedimentation chamber (203) and has a through groove. The end of each connector (205) away from the card block (204) is fastened to the outer wall of the inlet (202). It also includes a filter chamber (301), which is snapped into the side of the limiting block (201) away from the drift tube (102). A positioning tube (302) is connected through the top of the filter chamber (301), and a liquid input tube (303) is connected through the outside of the positioning tube (302). A piston (304) is provided inside the positioning tube (302) to fit the inner wall of the positioning tube (302).

2. The electronic-grade hydrofluoric acid recovery device according to claim 1, characterized in that: A round rod (305) is fixedly connected inside the piston (304), and a collection groove (306) located directly below the positioning tube (302) is fixedly connected to the outer side of the middle position of the round rod (305).

3. The electronic-grade hydrofluoric acid recovery device according to claim 1, characterized in that: The nanofiltration membrane (206) is disposed at the connection between the limiting block (201) and the filter chamber (301), and the nanofiltration membrane (206) is disposed in close contact with the inner wall of the filter chamber (301).

4. The electronic-grade hydrofluoric acid recovery device according to claim 1, characterized in that: It also includes a positioning tube 2 (401) that runs through the bottom of the filter chamber (301), and a liquid output tube (402) is connected through the outside of the positioning tube 2 (401).

5. The electronic-grade hydrofluoric acid recovery device according to claim 2, characterized in that: The end of the round rod (305) away from the piston one (304) is fixedly connected to the piston two (403), and the bottom of the piston two (403) is fitted with a support member (404) whose other end is fixedly connected to the bottom of the inner wall of the positioning tube two (401).

6. The electronic-grade hydrofluoric acid recovery device according to claim 4, characterized in that: The inner wall of the positioning tube 2 (401) is fitted with a support ring (405) located on the outer side below the piston 2 (403). The support ring (405) is penetrated by a support member (404) at one end away from the inner wall of the positioning tube 2 (401). Two axially symmetrical hydraulic rods (406) are fixedly connected to the two sides of the bottom of the support ring (405). The end of each hydraulic rod (406) away from the support ring (405) is fixedly connected to the limiting member (407).

7. The electronic-grade hydrofluoric acid recovery device according to claim 6, characterized in that: The limiting member (407) is fixedly connected to the inner wall of the positioning tube (401).

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