Method for recovering electronic grade hydrofluoric acid

Abstract

The present application discloses a method for recovering electronic-grade hydrofluoric acid, which can be applied to a hydrofluoric acid recovery system, wherein the hydrofluoric acid recovery system includes at least two adsorption units, and the adsorption units include resin adsorption towers. The method for recovering electronic-grade hydrofluoric acid includes at least one of the adsorption units performing an adsorption operation, while the remaining adsorption units perform a regeneration operation to restore the adsorption capacity. The regeneration operation includes introducing ultrapure water into the resin adsorption tower performing the regeneration operation, and the ultrapure water replaces the hydrofluoric acid raw material liquid remaining in the resin adsorption tower performing the regeneration operation. After the resin adsorption tower performing the adsorption operation reaches saturation, the hydrofluoric acid recovery system enters the next cycle, and the resin adsorption tower performing the adsorption operation performs a regeneration operation in the next cycle, and the resin adsorption tower performing the regeneration operation performs an adsorption operation in the next cycle, so as to achieve the uninterrupted production of electronic-grade hydrofluoric acid by the hydrofluoric acid recovery system.

Description

Technical Field

[0001] The invention relates to the technical field of recovery of hydrofluoric acid, in particular to a method for recovering electronic-grade hydrofluoric acid. Background Art

[0002] Photovoltaic solar energy is a scientific technology that converts solar radiation energy into electrical energy through the photovoltaic effect of semiconductor materials. The core of this technology lies in solar panels. At present, in the production process of solar panels, it is necessary to use hydrofluoric acid of various concentrations for soaking and cleaning to remove impurities such as oxide layers, particulate matter and metal ions on the surface of silicon wafers. After a certain period of use, the concentration and purity of the hydrofluoric acid solution in the cleaning tank will decrease, resulting in a decrease in the effect of cleaning silicon wafers. Therefore, the staff needs to replace the hydrofluoric acid solution regularly. The waste hydrofluoric acid solution discharged from the cleaning tank contains a large amount of fluorine resources. In order to avoid waste of resources, the waste hydrofluoric acid solution needs to enter the recycling and treatment system for treatment.

[0003] The hydrofluoric acid raw material liquid extracted by the recovery and treatment system still contains a small amount of metal ions. In order to remove the metal ions, the hydrofluoric acid raw material liquid needs to be passed into the resin adsorption tower for adsorption operation. As the metal ions accumulate in the resin adsorption tower, the resin adsorption tower reaches a saturated state. In order to ensure the adsorption effect, the resin adsorption tower needs to suspend the adsorption operation and perform desorption regeneration. At this time, the resin adsorption tower cannot produce hydrofluoric acid solution, so the hydrofluoric acid recovery efficiency is low.

[0004] CN114213238A discloses a preparation method for reducing the iron ion content in a refined adipic acid product. The patent indicates that the concentration is a low-concentration nitric acid solution of about 4wt%, and the flow rate is controlled to be 1T / H by a flow meter 13 and a regulating valve 14, and enters an adsorption tower from the top through an electromagnetic valve 04, and the copper ions, vanadium ions, and iron ions adsorbed by the resin in the adsorption tower are replaced by hydrogen ions in the nitric acid solution, and the resin is restored to a hydrogen-type resin. However, in the later stage of desorption, the metal ion content in the adsorption tower is less, so the rate of ion exchange between the metal ions and the regeneration liquid is slow, and then a large amount of regeneration liquid is introduced, which can not speed up the exchange rate but will cause a waste of regeneration liquid resources. Summary of the invention

[0005] In order to solve the above technical problems and achieve at least one advantage of the present invention, the present invention provides a method for recovering electronic-grade hydrofluoric acid, which can be applied to a hydrofluoric acid recovery system, wherein the hydrofluoric acid recovery system comprises at least two adsorption units, wherein the adsorption unit comprises a resin adsorption tower, and wherein the method for recovering electronic-grade hydrofluoric acid comprises the following operations:

[0006] At least one of the adsorption units performs an adsorption operation, and a hydrofluoric acid raw material liquid is introduced into the resin adsorption tower performing the adsorption operation, so that the resin adsorption tower performing the adsorption operation adsorbs metal ions in the hydrofluoric acid raw material liquid to obtain electronic grade hydrofluoric acid;

[0007] At the same time, the remaining adsorption units perform a regeneration operation, which includes the following steps:

[0008] Stopping the introduction of hydrofluoric acid raw material solution into the resin adsorption tower performing the regeneration operation, and introducing ultrapure water into the resin adsorption tower performing the regeneration operation, so as to replace the hydrofluoric acid raw material solution remaining in the resin adsorption tower performing the regeneration operation with the ultrapure water;

[0009] After the hydrofluoric acid raw material liquid remaining in the resin adsorption tower performing the regeneration operation is completely replaced by ultrapure water, the ultrapure water is stopped from being introduced into the resin adsorption tower performing the regeneration operation, and the regeneration liquid is introduced into the resin adsorption tower performing the regeneration operation at a preset flow rate, and the metal ions adsorbed by the resin adsorption tower performing the regeneration operation are ion-exchanged with the regeneration liquid and discharged from the tower with the regeneration liquid;

[0010] After the metal ions adsorbed by the resin adsorption tower performing the regeneration operation are exchanged with the regeneration liquid, the regeneration liquid is stopped from being introduced into the resin adsorption tower performing the regeneration operation, and a water washing liquid is introduced into the resin adsorption tower performing the regeneration operation, so that the water washing liquid flushes out the regeneration liquid attached to the resin adsorption tower performing the regeneration operation;

[0011] After the regeneration liquid attached to the resin adsorption tower performing the regeneration operation is completely replaced by the water washing liquid, the water washing liquid is stopped from being introduced into the resin adsorption tower performing the regeneration operation, and electronic grade hydrofluoric acid is introduced into the bottom of the resin adsorption tower performing the regeneration operation, and the electronic grade hydrofluoric acid replaces the residual water washing liquid in the resin adsorption tower performing the regeneration operation;

[0012] Cyclic adsorption operation and regeneration operation, after the resin adsorption tower performing the adsorption operation reaches saturation, the hydrofluoric acid recovery system enters the next cycle, the resin adsorption tower performing the adsorption operation performs the regeneration operation in the next cycle, and the resin adsorption tower performing the regeneration operation performs the adsorption operation in the next cycle.

[0013] According to one embodiment of the present invention, the resin adsorption towers included in each of the multiple adsorption units are connected in series through a pipe valve, and after the regeneration liquid attached to the resin adsorption tower performing the regeneration operation is completely replaced by the washing liquid, part of the electronic-grade hydrofluoric acid purified by the resin adsorption tower performing the adsorption operation is passed to the resin adsorption tower performing the regeneration operation.

[0014] According to an embodiment of the present invention, the regeneration liquid is a mixed liquid of ultrapure water and acid in a predetermined ratio.

[0015] According to an embodiment of the present invention, the hydrochloric acid concentration of the regeneration liquid is 4-5%; the volume of the regeneration liquid used: the volume of the resin is 2-3:1.

[0016] According to an embodiment of the present invention, the hydrofluoric acid raw material liquid remaining in the resin adsorption tower performing the regeneration operation is replaced by ultrapure water and introduced into the hydrofluoric acid raw material tank.

[0017] According to one embodiment of the present invention, after the metal ions adsorbed by the resin adsorption tower performing the regeneration operation are exchanged with the regeneration liquid, the regeneration liquid is first flushed through the resin adsorption tower performing the regeneration operation at a preset flow rate. After the regeneration liquid has been flushed for a preset time, the regeneration liquid is stopped from being introduced into the resin adsorption tower performing the regeneration operation and the discharge of the regeneration liquid is prohibited. The regeneration liquid is discharged after being retained in the resin adsorption tower performing the regeneration operation for a preset time.

[0018] According to one embodiment of the present invention, after the metal ions adsorbed by the resin adsorption tower performing the regeneration operation are exchanged with the regeneration liquid, the water washing liquid is passed into the resin adsorption tower performing the regeneration operation, and the water washing liquid is defined as the first water washing liquid, the second water washing liquid and the third water washing liquid according to the different time periods of the water washing liquid passed into the resin adsorption tower, wherein the second water washing liquid and the third water washing liquid are both implemented as ultrapure water;

[0019] Step S31: the first water washing liquid is passed into the resin adsorption tower performing the regeneration operation and rinsed for a preset time, and the first water washing liquid discharged from the resin adsorption tower performing the regeneration operation is discharged into the analysis tank;

[0020] Step S32: After step S31, the first water washing liquid discharged from the resin adsorption tower performing the regeneration operation stops being passed into the desorption tank, the second water washing liquid continues to be passed into the resin adsorption tower and rinses for a preset time, and the second water washing liquid discharged from the resin adsorption tower is passed into the recovery water tank;

[0021] Step S33: After step S32, the second water washing liquid discharged from the resin adsorption tower performing the regeneration operation stops entering the recovery water tank, and the third water washing liquid continues to enter the resin adsorption tower performing the regeneration operation and flushes for a preset time. The third water washing liquid discharged from the resin adsorption tower performing the regeneration operation can be used as the first water washing liquid used in step S31. When the third water washing liquid discharged from the resin adsorption tower is detected to be neutral, the third water washing liquid can be stopped from entering the resin adsorption tower.

[0022] According to an embodiment of the present invention, the electronic-grade hydrofluoric acid produced in the adsorption operation flows to the first hydrofluoric acid storage tank through the first filter to remove particulate matter in the electronic-grade hydrofluoric acid flowing to the first hydrofluoric acid storage tank.

[0023] According to one embodiment of the present invention, the residual washing liquid in the resin adsorption tower performing the regeneration operation flows to the second hydrofluoric acid storage tank along with the hydrofluoric acid solution through the second filter to remove particulate matter in the hydrofluoric acid solution flowing to the second hydrofluoric acid storage tank.

[0024] According to an embodiment of the present invention, the hydrofluoric acid solution stored in the second hydrofluoric acid storage tank is configured with high-purity water for use as a regeneration liquid.

[0025] Compared with the prior art, the method for recovering electronic-grade hydrofluoric acid provided by the present invention has the following technical effects:

[0026] 1. In the present invention, while at least one of the adsorption units performs an adsorption operation, the remaining adsorption units perform a regeneration operation, so that the system can continuously produce a hydrofluoric acid solution.

[0027] 2. The present invention adopts a dynamic-first-static-later mode during desorption, which ensures the desorption effect of the resin adsorption tower while saving the amount of regeneration liquid.

[0028] 3. In the later stage of water washing, the residual amount of regeneration liquid in the resin adsorption tower is low, so the water washing liquid discharged during this period is used for initial water washing, saving the amount of water washing liquid.

[0029] 4. In the present invention, when the adsorption unit is regenerated, the remaining impurities are not introduced into the resin adsorption tower, so that the cleanliness of the regenerated resin adsorption tower is high, so the regenerated resin adsorption tower can obtain a higher adsorption capacity, and can fully adsorb the hydrofluoric acid raw material liquid, thereby obtaining a high-cleanliness hydrofluoric acid solution. In addition, the present invention adopts backwashing after water washing, and uses the purified hydrofluoric acid solution to replace the residual water washing liquid in the resin adsorption tower to avoid dilution of the hydrofluoric acid solution purified by the resin adsorption tower, thereby obtaining a high-concentration hydrofluoric acid solution, and then obtaining electronic grade hydrofluoric acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A flow chart of the tower regeneration method for a hydrofluoric acid recovery device according to the present invention is shown.

[0031] Figure 2 A schematic flow chart of the adsorption system of the present invention is shown.

[0032] Figure ID

[0033] 100, adsorption unit; 100A, first adsorption unit; 100B, second adsorption unit; 110, resin adsorption tower; 120, pipe member; 121, first liquid inlet pipe group; 1211, feed pipe; 1212, collection pipe; 1213, backwash liquid inlet pipe; 122, first liquid outlet pipe group; 1221, hydrofluoric acid liquid outlet pipe; 1222, sewage pipe; 1223, backwash liquid outlet pipe; 130, valve member; 131, first inlet control valve group; 1311, raw material inlet control valve; 1312, inlet control main valve; 1313, backwash liquid inlet control valve; 132, first outlet control valve group; 1321, hydrofluoric acid liquid outlet control valve; 1322, sewage main valve; 1323, backwash liquid outlet control valve;

[0034] 200, filter unit; 210, first filter; 220, second filter;

[0035] 300, regeneration control unit; 310, second liquid inlet pipe group; 311, first water inlet pipe; 312, regeneration liquid inlet pipe; 313, second water inlet pipe; 320, second control inlet valve group; 321, first water inlet valve; 322, regeneration liquid control inlet valve; 323, second water inlet valve;

[0036] 400, external discharge control unit; 410, second liquid outlet pipe group; 411, aqueous solution outlet pipe; 412, regeneration liquid outlet pipe; 413, first drain pipe; 414, second drain pipe; 415, third drain pipe; 420, second control outlet valve group; 422, regeneration liquid control outlet valve; 423, first drain valve; 424, second drain valve; 425, third drain valve;

[0037] 500, Recycling water tanks;

[0038] 600, analysis tank;

[0039] 700. The second hydrofluoric acid storage tank;

[0040] 800, the first hydrofluoric acid storage tank;

[0041] 900. Hydrofluoric acid raw material tank. DETAILED DESCRIPTION

[0042] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0043] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0044] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0045] refer to Figure 1 to Figure 2 A hydrofluoric acid recovery system according to a preferred embodiment of the present invention will be described in detail below. The hydrofluoric acid recovery system includes at least one adsorption unit 100.

[0046] The adsorption unit 100 includes a resin adsorption tower 110, a pipe member 120 and a valve member 130. The pipe member 120 includes a first liquid inlet pipe group 121 and a first liquid outlet pipe group 122. The valve member 130 includes a first inlet control valve group 131 and a first outlet control valve group 132.

[0047] The first liquid inlet pipe group 121 includes a feed pipe 1211, and the feed pipe 1211 is respectively connected to the resin adsorption tower 110 and the hydrofluoric acid raw material tank 900. The hydrofluoric acid raw material tank 900 stores a hydrofluoric acid raw material liquid, and the hydrofluoric acid raw material liquid includes a hydrofluoric acid solution and metal cations, etc., wherein the metal cations include Na, Ni, Cr, Mn, Co, etc. The first control inlet valve group 131 includes a raw material control inlet valve 1311. The raw material control inlet valve 1311 is arranged on the feed pipe 1211 to control the on-off of the flow path of the hydrofluoric acid raw material liquid from the feed pipe 1211 into the resin adsorption tower 110.

[0048] The first liquid outlet pipe group 122 includes a hydrofluoric acid liquid outlet pipe 1221, and the hydrofluoric acid liquid outlet pipe 1221 is respectively connected to the resin adsorption tower 110 and the first hydrofluoric acid storage tank 800. The first control outlet valve group 132 includes a hydrofluoric acid liquid control outlet valve 1321, and the hydrofluoric acid liquid control outlet valve 1321 is arranged on the hydrofluoric acid liquid outlet pipe 1221, and is used to control the opening and closing of the hydrofluoric acid liquid outlet pipe 1221.

[0049] The resin adsorption tower 110 adopts a hydrogen-type strong acid cation exchange column, and the column is filled with a hydrogen-type strong acid cation exchange resin. The hydrogen-type strong acid cation exchange resin contains a large number of strong acid groups, for example, sulfonic acid group -SO3H. It is worth mentioning that the hydrogen-type strong acid cation exchange resin has a strong dissociation ability, and can dissociate in acidic or alkaline solutions and then undergo ion exchange. In this way, when the raw material control inlet valve 1311 and the hydrofluoric acid liquid control outlet valve 1321 are opened, the hydrofluoric acid raw material liquid in the hydrofluoric acid raw material tank 900 enters the resin adsorption tower 110 through the feed pipe 1211, and the strong acid groups dissociate to generate hydrogen ions and acid radical ions, such as SO3 - The dissociated hydrogen ions exchange with the metal cations in the hydrofluoric acid raw material solution, so that the metal ions are adsorbed in the resin adsorption tower 110 , and the dissociated hydrogen ions are discharged into the first hydrofluoric acid storage tank 800 through the hydrofluoric acid solution discharge pipe 1221 along with the hydrofluoric acid solution.

[0050] Preferably, the hydrofluoric acid recovery system includes a filter unit 200. The filter unit 200 includes a first filter 210, which is installed on the hydrofluoric acid liquid discharge pipe 1221 to remove particulate matter doped with the hydrofluoric acid solution discharged into the first hydrofluoric acid storage tank 800.

[0051] In one example, the first filter 210 is implemented as a 0.01-0.05 μm filter.

[0052] It is worth mentioning that after the resin adsorption tower 110 is saturated, the raw material inlet control valve 1311 and the hydrofluoric acid liquid outlet control valve 1321 are closed to prevent the hydrofluoric acid raw material liquid from continuing to be injected into the saturated resin adsorption tower 110 and the unpurified hydrofluoric acid raw material liquid from entering the first hydrofluoric acid storage tank 800.

[0053] Furthermore, the hydrofluoric acid recovery system also includes a regeneration control unit 300. The regeneration control unit 300 includes a second liquid inlet pipe group 310 and a second inlet control valve group 320. The first liquid outlet pipe group 122 also includes a sewage pipe 1222, and the sewage pipe 1222 is connected to the resin adsorption tower 110. The first outlet control valve group 132 also includes a sewage main valve 1322, and the sewage main valve 1322 is installed on the sewage pipe 1222 to control the sewage pipe 1222 to be opened and closed.

[0054] The second liquid inlet pipe group 310 includes a first water inlet pipe 311, which is connected to the resin adsorption tower 110. The second control inlet valve group 320 includes a first water inlet valve 321, which is installed on the first water inlet pipe 311 to control the on-off of the flow path of the aqueous solution from the first water inlet pipe 311 into the resin adsorption tower 110. After the resin adsorption tower 110 is saturated, the first water inlet valve 321 and the main sewage valve 1322 are opened, so that the aqueous solution enters the resin adsorption tower 110 through the first water inlet pipe 311, and the hydrofluoric acid raw material liquid remaining in the resin adsorption tower 110 is replaced by the aqueous solution and discharged through the sewage pipe 1222.

[0055] The second liquid inlet pipe group 310 also includes a regeneration liquid inlet pipe 312, and the regeneration liquid inlet pipe 312 is connected to the resin adsorption tower 110. The second control inlet valve group 320 also includes a regeneration liquid control inlet valve 322. The regeneration liquid control inlet valve 322 is installed on the regeneration liquid inlet pipe 312 to control the flow path of the regeneration liquid into the resin adsorption tower 110 through the regeneration liquid inlet pipe 312. After the hydrofluoric acid raw material liquid remaining in the resin adsorption tower 110 is completely replaced by the aqueous solution, the first water inlet valve 321 is closed and the regeneration liquid control inlet valve 322 is opened, so that the regeneration liquid enters the resin adsorption tower 110 through the regeneration liquid inlet pipe 312, and the regeneration liquid exchanges ions with the metal ions adsorbed by the resin adsorption tower 110, so that the metal ions adsorbed by the resin adsorption tower 110 are discharged through the drain pipe 1222 along with the regeneration liquid, and then the resin adsorption tower 110 is regenerated due to the restoration of adsorption capacity.

[0056] The second liquid inlet pipe group 310 also includes a second water inlet pipe 313, and the second water inlet pipe 313 is connected to the resin adsorption tower 110. The second controlled inlet valve group 320 also includes a second water inlet valve 323. The second water inlet valve 323 is installed on the second water inlet pipe 313 to control the flow path of the water washing liquid entering the resin adsorption tower 110 through the second water inlet pipe 313. After the metal ions adsorbed in the resin adsorption tower 110 are exchanged with the regeneration liquid ions, the regeneration liquid controlled inlet valve 322 is closed and the second water inlet valve 323 is opened, so that the water washing liquid is injected into the resin adsorption tower 110, and the water washing liquid flushes the regeneration liquid attached to the resin adsorption tower 110 out of the resin adsorption tower 110 to improve the cleanliness of the resin adsorption tower 110.

[0057] Preferably, the first liquid inlet pipe group 121 further includes a collection pipe 1212. The first water inlet pipe 311, the second water inlet pipe 313 and the regeneration liquid inlet pipe 312 are all connected to the resin adsorption tower 110 through the collection pipe 1212. The first control inlet valve group 131 further includes a control inlet main valve 1312. The control inlet main valve 1312 is installed on the collection pipe 1212 to control the circulation of the collection pipe 1212.

[0058] The first liquid inlet pipe group 121 further includes a backwash liquid inlet pipe 1213, and the first liquid outlet pipe group 122 further includes a backwash liquid outlet pipe 1223, and both the backwash liquid inlet pipe 1213 and the backwash liquid outlet pipe 1223 are connected to the resin adsorption tower 110. The first control inlet valve group 131 further includes a backwash liquid control inlet valve 1313, and the backwash liquid control inlet valve 1313 is installed on the backwash liquid inlet pipe 1213, and is used to control the flow path of the backwash liquid entering the resin adsorption tower 110 through the backwash liquid inlet pipe 1213. The first control outlet valve group 132 includes a backwash liquid control outlet valve 1323, and the backwash liquid control outlet valve 1323 is installed on the backwash liquid outlet pipe 1223. After the resin adsorption tower 110 is washed with water, the second water inlet valve 323, the main sewage valve 1322 and the main inlet control valve 1312 are closed, and the backwashing liquid inlet control valve 1313 and the backwashing liquid outlet control valve 1323 are opened, so that the backwashing liquid enters the resin adsorption tower 110 through the backwashing liquid inlet pipe 1213. It is worth mentioning that the backwashing liquid is a hydrofluoric acid solution obtained by purifying the hydrofluoric acid raw material liquid by the resin adsorption tower 110. The backwashing liquid replaces the residual water washing liquid in the resin adsorption tower 110 and is discharged from the backwashing liquid outlet pipe 1223, so that the hydrofluoric acid solution obtained by purifying the hydrofluoric acid raw material liquid by the regenerated resin adsorption tower 110 can reach a predetermined concentration.

[0059] Preferably, the backwash liquid inlet pipe 1213 is connected to the first hydrofluoric acid storage tank 800 , so that the hydrofluoric acid solution stored in the first hydrofluoric acid storage tank 800 can be passed into the resin adsorption tower 110 through the backwash liquid inlet pipe 1213 .

[0060] Preferably, the backwash liquid discharge pipe 1223 is connected to the second hydrofluoric acid storage tank 700, and the water washing liquid is discharged from the resin adsorption tower 110 into the second hydrofluoric acid storage tank 700 along with the backwash liquid. It can be understood that the concentration and cleanliness of the hydrofluoric acid solution stored in the second hydrofluoric acid storage tank 700 are lower than those of the hydrofluoric acid solution stored in the first hydrofluoric acid storage tank 800.

[0061] Furthermore, the filtration unit 200 further includes a second filter 220 . The second filter 220 is installed on the backwash liquid discharge pipe 1223 to remove particulate matter mixed in the low-standard hydrofluoric acid solution discharged to the second hydrofluoric acid storage tank 700 .

[0062] In one example, the second filter 220 is implemented as a 0.01-0.05 μm filter.

[0063] Preferably, the hydrofluoric acid recovery system further comprises an external discharge control unit 400. The external discharge control unit 400 comprises a second liquid outlet pipe group 410 and a second control outlet valve group 420.

[0064] The second liquid outlet pipe group 410 includes an aqueous solution outlet pipe 411, and the second control outlet valve group 420 includes an aqueous solution control outlet valve 421. The aqueous solution outlet pipe 411 is respectively connected to the sewage pipe 1222 and the hydrofluoric acid raw material tank 900. The aqueous solution control outlet valve 421 is installed on the aqueous solution outlet pipe 411, and is used to control the flow path of the aqueous solution discharged from the sewage pipe 1222 into the hydrofluoric acid raw material tank 900 through the aqueous solution outlet pipe 411.

[0065] The second liquid outlet pipe group 410 includes a regeneration liquid outlet pipe 412, and the second control outlet valve group 420 includes a regeneration liquid control outlet valve 422. The regeneration liquid outlet pipe 412 is respectively connected to the sewage pipe 1222 and the analytical tank 600. The regeneration liquid control outlet valve 422 is installed on the regeneration liquid outlet pipe 412 to control the flow path of the regeneration liquid discharged from the sewage pipe 1222 to be discharged into the analytical tank 600 through the regeneration liquid outlet pipe 412.

[0066] The second liquid outlet pipe group 410 includes a first drain pipe 413, a second drain pipe 414 and a third drain pipe 415, and the second control valve group 420 includes a first drain valve 423, a second drain valve 424 and a third drain valve 425. The first drain pipe 413 is connected to the sewage pipe 1222 and the analytical tank 600 respectively, and the first drain valve 423 is installed on the first drain pipe 413 to control the flow of the washing liquid discharged from the sewage pipe 1222 to the analytical tank 600 through the first drain pipe 413. The second drain pipe 414 is connected to the sewage pipe 1222 and the recovery water tank 500 respectively. The second drain valve 424 is installed on the second drain pipe 414 to control the flow of the washing liquid discharged from the sewage pipe 1222 to the recovery water tank 500 through the second drain pipe 414. The third drain pipe 415 is connected to the sewage pipe 1222 , and the third drain valve 425 is installed on the third drain pipe 415 to control the flow of the washing liquid discharged from the sewage pipe 1222 through the third drain pipe 415 .

[0067] Preferably, the third drainage pipe 415 is connected to the second water inlet pipe 313 , so that the washing liquid discharged from the third drainage pipe 415 can be re-injected into the resin adsorption tower 110 via the second water inlet pipe 313 .

[0068] A working method of the hydrofluoric acid recovery system is now proposed, comprising the following steps:

[0069] (i) Adsorption operation: Open the raw material inlet control valve 1311 and the hydrofluoric acid liquid outlet control valve 1321 to allow the hydrofluoric acid raw material liquid in the hydrofluoric acid raw material tank 900 to enter the resin adsorption tower 110 through the feed pipe 1211, so that the resin adsorption tower 110 adsorbs metal ions in the hydrofluoric acid raw material liquid, and the purified hydrofluoric acid solution is discharged into the first hydrofluoric acid storage tank 800 through the hydrofluoric acid liquid discharge pipe 1221.

[0070] Preferably, the hydrofluoric acid solution flowing to the first hydrofluoric acid storage tank 800 is filtered through the first filter 210 to remove particulate matter.

[0071] (ii) Regeneration operation: After the resin adsorption tower 110 is saturated, the raw material inlet control valve 1311 and the hydrofluoric acid liquid outlet control valve 1321 are closed to stop the introduction of the hydrofluoric acid raw material liquid into the saturated resin adsorption tower 110 .

[0072] (1) Replacement: Open the main water inlet control valve 1312, the main sewage discharge valve 1322, the first water inlet valve 321 and the aqueous solution control valve 421 to allow the aqueous solution to enter the saturated resin adsorption tower 110 through the first water inlet pipe 311, and the hydrofluoric acid raw material liquid remaining in the resin adsorption tower 110 is replaced by the aqueous solution. The replaced hydrofluoric acid raw material liquid flows into the hydrofluoric acid raw material tank 900 along with the aqueous solution through the aqueous solution discharge pipe 411.

[0073] Preferably, the aqueous solution is ultrapure water, which has a very high content of water molecules and almost no impurities, so the use of ultrapure water will not introduce other impurities into the resin adsorption tower 110 .

[0074] (2) Desorption: After the hydrofluoric acid raw material liquid remaining in the resin adsorption tower 110 is completely replaced by the aqueous solution, the first water inlet valve 321 and the aqueous solution control outlet valve 421 are closed, and the regeneration liquid control inlet valve 322 and the regeneration liquid control outlet valve 422 are opened, so that the regeneration liquid enters the resin adsorption tower 110 through the regeneration liquid inlet pipe 312, and the regeneration liquid exchanges ions with the metal ions adsorbed on the resin adsorption tower 110. The metal ions adsorbed by the resin adsorption tower 110 are discharged into the analysis tank 600 along with the regeneration liquid through the regeneration liquid discharge pipe 412, and the resin adsorption tower 110 restores its adsorption capacity.

[0075] In step (2), it includes step (S21): the regeneration liquid is injected into the resin adsorption tower 110 at a preset flow rate through the regeneration liquid inlet pipe 312, the metal ions adsorbed by the resin adsorption tower 110 undergo ion exchange with the flowing regeneration liquid and are discharged into the analysis tank 600 along with the regeneration liquid through the regeneration liquid discharge pipe 412.

[0076] Preferably, in step (2), a step (S22) is further included: after the regeneration liquid is flushed for a preset time, the regeneration liquid control inlet valve 322 and the regeneration liquid control outlet valve 422 are closed to stop the regeneration liquid from being introduced into the resin adsorption tower 110 and also to prohibit the regeneration liquid from being discharged from the resin adsorption tower 110. The regeneration liquid retained in the resin adsorption tower 110 is fully exchanged with the remaining metal ions, and the regeneration liquid control outlet valve 422 is opened after the regeneration liquid is retained for a preset time, so that the regeneration liquid is discharged to the analysis tank 600.

[0077] It can be understood that in the initial stage of step (2), the metal ion content in the resin adsorption tower 110 is high, and the exchange rate can be accelerated by using the flowing regeneration liquid to exchange ions with the metal ions; while in the later stage of desorption, the metal ion content in the resin adsorption tower 110 is low, and the amount of regeneration liquid required is small, so the static regeneration liquid can be used to fully contact with the metal ions to achieve the purpose of completely purifying the resin adsorption tower 110. This mode of moving first and then static can not only ensure the desorption effect of the resin adsorption tower 110, but also save the amount of regeneration liquid.

[0078] Preferably, the regeneration liquid is made of ultrapure water and acid in a predetermined ratio, so that the ultrapure water will not introduce other impurities into the resin adsorption tower 110 , thereby improving the cleanliness of the resin adsorption tower 110 .

[0079] In a preferred embodiment, the hydrochloric acid concentration in the regeneration liquid is 4-5%, and the ultrapure water meets the EW-II electronic grade standard (GB / T 11446.1-2013); the volume of the regeneration liquid used: the volume of the resin = 2-3:1.

[0080] Furthermore, the regeneration operation further includes step (3) water washing:

[0081] After step (2), the regeneration liquid control inlet valve 322 and the regeneration liquid control outlet valve 422 are closed and the second water inlet valve 323 is opened to allow the washing liquid to pass into the resin adsorption tower 110 through the second water inlet pipe 313. The washing liquid will flush the regeneration liquid attached to the resin adsorption tower 110 out of the resin adsorption tower 110, thereby improving the cleanliness of the resin adsorption tower 110.

[0082] It is worth mentioning that, according to the different time periods of the washing liquid introduced into the resin adsorption tower 110, the washing liquid is defined as the first washing liquid, the second washing liquid and the third washing liquid.

[0083] Preferably, in step (3), step S31 is included: the first drain valve 423 is opened, the first water washing liquid is passed into the resin adsorption tower 110 and rinsed for a preset time, and the first water washing liquid discharged from the resin adsorption tower 110 is discharged into the analysis tank 600 through the first drain pipe 413. Since a large amount of regeneration liquid is retained in the resin adsorption tower 110 at the initial stage of water washing, a large amount of regeneration liquid is discharged from the resin adsorption tower 110 with the first water washing liquid and passed into the analysis tank 600, so as to recover metal ions later.

[0084] In step (3), step S32 is also included: after step S31, the first drain valve 423 is closed and the second drain valve 424 is opened, and the washing liquid discharged from the resin adsorption tower 110 stops entering the desorption tank 600. Then the second washing liquid is passed into the resin adsorption tower 110 and rinsed for a preset time, and the second washing liquid discharged from the resin adsorption tower 110 is passed into the recovery water tank 500 through the second drain pipe 414. Since the regeneration liquid content in the resin adsorption tower 110 is low in the middle of the washing, the washing liquid in the recovery water tank 500 is subsequently recycled.

[0085] In step (3), step S33 is also included: after step S32, the second drain valve 424 is closed and the third drain valve 425 is opened, the washing liquid discharged from the resin adsorption tower 110 stops entering the recovery water tank 500, the third washing liquid continues to be introduced into the resin adsorption tower 900 and rinses for a preset time, and the third washing liquid discharged from the resin adsorption tower 110 is injected into the second water inlet pipe 313 through the third drain pipe 415 to be reused as the first washing liquid used in step S31. Since the content of the regeneration liquid in the resin adsorption tower 110 is very small at the end of the water washing, the washing liquid discharged from the resin adsorption tower 110 during this period can be reused as the washing liquid used in step (S31) or directly discharged.

[0086] Preferably, in step S33, when the third water washing liquid discharged from the resin adsorption tower 900 is detected to be neutral, the introduction of the third water washing liquid into the resin adsorption tower 900 is stopped.

[0087] In one embodiment, the second washing liquid and the third washing liquid are both implemented as ultrapure water. It is also understandable that the washing liquid removes the residual regeneration liquid in the resin adsorption tower 110 without introducing other impurities into the resin adsorption tower 110, so that the resin adsorption tower 110 can obtain high cleanliness after regeneration. In this way, the resin adsorption tower 110 after washing has high cleanliness, and the resin adsorption tower 110 after regeneration has high adsorption power, so that the metal ions in the hydrofluoric acid raw material liquid passed into the resin adsorption tower 110 can be fully adsorbed, and a high-cleanliness hydrofluoric acid solution is obtained.

[0088] Furthermore, the regeneration operation further includes step (4) backwashing:

[0089] After step (3), the raw material control inlet valve 1311 and the hydrofluoric acid liquid control outlet valve 1321 are closed, and the backwash liquid control outlet valve 1323 and the backwash liquid control inlet valve 1313 are opened, so that the hydrofluoric acid solution in the first hydrofluoric acid storage tank 800 is introduced from the bottom of the resin adsorption tower 110 through the backwash liquid inlet pipe 1213, and the hydrofluoric acid solution replaces the residual water washing liquid in the resin adsorption tower 110. The water washing liquid is discharged into the second hydrofluoric acid storage tank 700 along with the hydrofluoric acid solution through the backwash liquid discharge pipe 1223, thereby ensuring that the hydrofluoric acid solution obtained by purifying the hydrofluoric acid raw material liquid by the resin adsorption tower 110 can reach a high concentration.

[0090] In this way, the hydrofluoric acid solution adsorbed by the regenerated resin adsorption tower 110 can reach both high concentration and high cleanliness, so the hydrofluoric acid solution adsorbed by the resin adsorption tower 110 can reach electronic grade standards.

[0091] In one example, it was detected that the Ni content in the hydrofluoric acid raw material liquid stored in the hydrofluoric acid raw material tank 900 was 156.47 ppb, the Cr content was 5.86 ppb, the Mn content was 9.25 ppb, the Co content was 22.99 ppb, and the Zr content was 1.53 ppb. After the hydrofluoric acid raw material liquid was adsorbed by the regenerated resin adsorption tower 110, the metal ion content in the discharged hydrofluoric acid solution was less than 1 ppb, reaching the electronic grade hydrofluoric acid standard, and can be directly used as a cleaning agent and etching agent for use in photovoltaic, integrated circuit and glass thinning industries.

[0092] It is worth mentioning that the hydrofluoric acid solution stored in the second hydrofluoric acid storage tank 700 can be used for the configuration of regeneration liquid and reused.

[0093] Preferably, the hydrofluoric acid recovery system includes a plurality of the adsorption units 100, and a plurality of the resin adsorption towers 110 are connected in series through a pipe valve, so that the plurality of the resin adsorption towers 110 operate in parallel to achieve the purpose of uninterruptedly purifying the hydrofluoric acid raw material liquid and producing the hydrofluoric acid solution.

[0094] In order to facilitate understanding by those skilled in the art, the following description will be made by taking the two resin adsorption towers 110 connected in series as an example, and the two adsorption units 100 are defined as a first adsorption unit 100A and a second adsorption unit 100B in sequence.

[0095] The hydrofluoric acid raw liquid is passed into the first adsorption unit 100A, and the first adsorption unit 100A adsorbs the metal ions in the hydrofluoric acid raw liquid, and the produced hydrofluoric acid solution is discharged from the first adsorption unit 100A into the first hydrofluoric acid storage tank 800. When the hydrofluoric acid solution discharged from the first adsorption unit 100A fails to meet the standard, the hydrofluoric acid raw liquid is passed into the second adsorption unit 100B, so that the second adsorption unit 100B performs the adsorption operation; at the same time, the first adsorption unit 100A performs the regeneration operation to restore the adsorption capacity. It is worth mentioning that when the first adsorption unit 100A enters the backwashing step, part of the hydrofluoric acid solution discharged from the second adsorption unit 100B is passed into the first adsorption unit 100A. When the hydrofluoric acid solution discharged from the second adsorption unit 100B fails to meet the standard, the second adsorption unit 100B stops introducing the hydrofluoric acid raw liquid, and introduces the hydrofluoric acid raw liquid into the regenerated first adsorption unit 100A, and the regenerated first adsorption unit 100A performs the adsorption operation. At the same time, the second adsorption unit 100B restores the adsorption capacity through the regeneration operation, and this cycle enables the hydrofluoric acid recovery system to continuously produce hydrofluoric acid solution with high adsorption efficiency.

[0096] It can be understood that the number of the adsorption units 100 provided in the hydrofluoric acid recovery system can be increased or decreased according to the time required for regeneration of a single resin adsorption tower 110 and the time required for a single resin adsorption tower 110 to reach saturation, thereby meeting the demand of the hydrofluoric acid recovery system for uninterrupted production of hydrofluoric acid solution.

[0097] It should be understood by those skilled in the art that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The advantages of the present invention have been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be deformed or modified in any way without departing from the principles.

Claims

1. A method for recovering electronic grade hydrofluoric acid, which can be applied to a hydrofluoric acid recovery system, wherein the hydrofluoric acid recovery system comprises at least two adsorption units, wherein the adsorption units comprise a resin adsorption tower, and wherein: The electronic-grade hydrofluoric acid recovery method comprises the following operations: at least one of the adsorption units performs an adsorption operation, and a hydrofluoric acid raw material liquid is introduced into the resin adsorption tower performing the adsorption operation, so that the resin adsorption tower performing the adsorption operation adsorbs metal ions in the hydrofluoric acid raw material liquid to obtain electronic-grade hydrofluoric acid; At the same time, the remaining adsorption units perform a regeneration operation, which includes the following steps: Stopping the introduction of hydrofluoric acid raw material solution into the resin adsorption tower performing the regeneration operation, and introducing ultrapure water into the resin adsorption tower performing the regeneration operation, so as to replace the hydrofluoric acid raw material solution remaining in the resin adsorption tower performing the regeneration operation with the ultrapure water; After the hydrofluoric acid raw material liquid remaining in the resin adsorption tower performing the regeneration operation is completely replaced by ultrapure water, the ultrapure water is stopped from being introduced into the resin adsorption tower performing the regeneration operation, and the regeneration liquid is introduced into the resin adsorption tower performing the regeneration operation at a preset flow rate, and the metal ions adsorbed by the resin adsorption tower performing the regeneration operation are ion-exchanged with the regeneration liquid and discharged from the tower with the regeneration liquid; After the metal ions adsorbed by the resin adsorption tower performing the regeneration operation are exchanged with the regeneration liquid, the regeneration liquid is stopped from being introduced into the resin adsorption tower performing the regeneration operation, and a water washing liquid is introduced into the resin adsorption tower performing the regeneration operation, so that the water washing liquid flushes out the regeneration liquid attached to the resin adsorption tower performing the regeneration operation; After the regeneration liquid attached to the resin adsorption tower performing the regeneration operation is completely replaced by the water washing liquid, the water washing liquid is stopped from being introduced into the resin adsorption tower performing the regeneration operation, and electronic grade hydrofluoric acid is introduced into the bottom of the resin adsorption tower performing the regeneration operation, and the electronic grade hydrofluoric acid replaces the residual water washing liquid in the resin adsorption tower performing the regeneration operation; Cyclic adsorption operation and regeneration operation, after the resin adsorption tower performing the adsorption operation reaches saturation, the hydrofluoric acid recovery system enters the next cycle, the resin adsorption tower performing the adsorption operation performs the regeneration operation in the next cycle, and the resin adsorption tower performing the regeneration operation performs the adsorption operation in the next cycle.

2. The method for recovering electronic grade hydrofluoric acid according to claim 1, characterized in that: The resin adsorption towers included in each of the multiple adsorption units are connected in series through a pipe valve. After the regeneration liquid attached to the resin adsorption tower performing the regeneration operation is completely replaced by the water washing liquid, part of the electronic grade hydrofluoric acid purified by the resin adsorption tower performing the adsorption operation is passed to the resin adsorption tower performing the regeneration operation.

3. The method for recovering electronic grade hydrofluoric acid according to claim 1, characterized in that: The regeneration liquid is a mixture of ultrapure water and acid in a predetermined ratio.

4. The method for recovering electronic grade hydrofluoric acid according to claim 3, characterized in that: The regeneration liquid is implemented as hydrochloric acid, wherein the concentration of hydrochloric acid in the regeneration liquid is 4-5%; the volume of the regeneration liquid used: the volume of the resin is 2-3:

1.

5. The method for recovering electronic grade hydrofluoric acid according to claim 1, characterized in that: The hydrofluoric acid raw material liquid remaining in the resin adsorption tower performing the regeneration operation is replaced by ultrapure water and introduced into the hydrofluoric acid raw material tank.

6. The method for recovering electronic grade hydrofluoric acid according to claim 1, characterized in that: After the metal ions adsorbed by the resin adsorption tower performing the regeneration operation are exchanged with the regeneration liquid, the regeneration liquid first flushes the resin adsorption tower performing the regeneration operation at a preset flow rate. After the regeneration liquid flushes for a preset time, the regeneration liquid is stopped from being introduced into the resin adsorption tower performing the regeneration operation and the discharge of the regeneration liquid is prohibited. The regeneration liquid is discharged after being retained in the resin adsorption tower performing the regeneration operation for a preset time.

7. The method for recovering electronic grade hydrofluoric acid according to any one of claims 1 to 6, characterized in that: After the metal ions adsorbed by the resin adsorption tower performing the regeneration operation are exchanged with the regeneration liquid, the washing liquid is passed into the resin adsorption tower performing the regeneration operation, and the washing liquid is defined as the first washing liquid, the second washing liquid and the third washing liquid according to the different time periods of the washing liquid passed into the resin adsorption tower, wherein the second washing liquid and the third washing liquid are both implemented as ultrapure water; Step S31: the first water washing liquid is passed into the resin adsorption tower performing the regeneration operation and rinsed for a preset time, and the first water washing liquid discharged from the resin adsorption tower performing the regeneration operation is discharged into the analysis tank; Step S32: After step S31, the first water washing liquid discharged from the resin adsorption tower performing the regeneration operation stops being passed into the desorption tank, the second water washing liquid continues to be passed into the resin adsorption tower and rinses for a preset time, and the second water washing liquid discharged from the resin adsorption tower is passed into the recovery water tank; Step S33: After step S32, the second water washing liquid discharged from the resin adsorption tower performing the regeneration operation stops entering the recovery water tank, and the third water washing liquid continues to enter the resin adsorption tower performing the regeneration operation and flushes for a preset time. The third water washing liquid discharged from the resin adsorption tower performing the regeneration operation can be used as the first water washing liquid used in step S31. When the third water washing liquid discharged from the resin adsorption tower is detected to be neutral, the third water washing liquid can be stopped from entering the resin adsorption tower.

8. The method for recovering electronic grade hydrofluoric acid according to claim 1, characterized in that: The electronic-grade hydrofluoric acid produced in the adsorption operation flows to the first hydrofluoric acid storage tank through the first filter to remove particulate matter in the electronic-grade hydrofluoric acid flowing to the first hydrofluoric acid storage tank.

9. The method for recovering electronic grade hydrofluoric acid according to claim 1, characterized in that: The residual washing liquid in the resin adsorption tower performing the regeneration operation flows to the second hydrofluoric acid storage tank through the second filter along with the hydrofluoric acid solution to remove particulate matter in the hydrofluoric acid solution flowing to the second hydrofluoric acid storage tank.

10. The method for recovering electronic grade hydrofluoric acid according to claim 9, characterized in that: The hydrofluoric acid solution stored in the second hydrofluoric acid storage tank is configured with high-purity water and used as a regeneration liquid.

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