Purification and recovery device for hydrofluoric acid waste liquid in electronic industry

Abstract

The utility model discloses a hydrofluoric acid waste liquid purification and recovery device in the electronic industry, which comprises a rectification device, a first membrane separation system, an adsorption device and a second membrane separation system which are arranged in sequence, a permeation side outlet of the first membrane separation system is connected with the adsorption device through a first condenser, a permeation side outlet of the second membrane separation system is connected with a product outlet, and a nitrogen inlet is formed in the bottom of the rectification device. According to the device, the concentration of hydrofluoric acid can be improved, impurities and metal ions in the hydrofluoric acid waste liquid in the electronic industry can be effectively removed, the product reaches the electronic-grade recycling standard, and the resource recycling rate is improved.

Description

Technical Field

[0001] This application relates to the field of waste liquid treatment technology in the electronics industry, and more specifically, to a purification and recovery device for hydrofluoric acid waste liquid in the electronics industry. Background Technology

[0002] Electronic-grade hydrofluoric acid is one of the key basic chemical materials in the microelectronics industry, mainly used in the manufacturing of integrated circuits and very large-scale integrated circuits for wafer surface cleaning, cleaning, and etching processes during chip processing. In the solar photovoltaic industry, it is used for silicon wafer surface cleaning and as an etching agent. It is used in the first process step from silicon ingot to silicon wafer to solar cell: the cleaning and texturing stage. In the LCD industry, it is used for glass substrate cleaning, as an etching agent for silicon nitride and silicon dioxide. However, after a period of use, hydrofluoric acid contains impurities and is discharged as waste liquid. The large amount of water, small amounts of hydrofluoric acid, particulate impurities, and metal ions significantly reduce the reuse value of hydrofluoric acid. Therefore, developing an effective purification and recycling technology for hydrofluoric acid waste liquid is of great significance for achieving resource recycling and environmental protection.

[0003] While existing technologies can purify hydrofluoric acid to some extent, several limitations remain. Multiple distillation columns are energy-intensive and require significant investment, increasing the cost of the recovery process and reducing economic efficiency. Chemical precipitation produces fluoride-containing sludge, which not only increases the difficulty of waste treatment but may also pose new environmental threats, and hydrofluoric acid cannot be recycled. Furthermore, ion exchange methods utilize ion exchange resins to adsorb impurity ions in solution; however, when treating high concentrations of metal ions, the solution easily reaches saturation, resulting in unsatisfactory removal of certain metal ions and limiting its application.

[0004] Therefore, there is an urgent need to develop more efficient and environmentally friendly technologies for the recycling of hydrofluoric acid wastewater. This new technology should be able to efficiently remove various impurities, including moisture, particulate matter, and metal ions, while ensuring the high purity of the recovered hydrofluoric acid. It should also be characterized by low energy consumption and low cost to improve the economic feasibility of the recycling process. Furthermore, the new technology should minimize secondary pollution, achieving true green environmental protection. Developing such advanced technologies can not only reduce environmental pollution but also lower production costs and improve resource recycling rates, which is of great significance for promoting the sustainable development of the electronics industry and achieving energy conservation and emission reduction goals. Utility Model Content

[0005] The purpose of this invention is to provide a hydrofluoric acid waste liquid purification and recycling device for the electronics industry, which can effectively remove moisture, impurities and metal ions from hydrofluoric acid waste liquid, improve the purity of hydrofluoric acid to meet electronic grade recycling standards, and at the same time reduce energy consumption and equipment corrosion risks, and improve resource recycling rate.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A purification and recovery device for hydrofluoric acid waste liquid in the electronics industry includes a distillation unit 1, a first membrane separation system 4, an adsorption unit 10, and a second membrane separation system 11 arranged sequentially.

[0008] The top outlet of the distillation unit 1 is connected to the first membrane separation system 4. The permeate-side outlet of the first membrane separation system 4 is connected to the adsorption unit 10 via the first condenser 6. The permeate-side outlet of the second membrane separation system 11 is connected to the product outlet.

[0009] The bottom of the distillation apparatus 3 is provided with a nitrogen inlet.

[0010] Furthermore, the top outlet of the distillation unit 1 is connected to the first membrane separation system 4 via a condenser 3.

[0011] Furthermore, the reflux-side outlet of the first membrane separation system 4 is connected to the inlet of the distillation unit 1 via the second condenser 5, forming a reflux.

[0012] Furthermore, the outlet of the first condenser 6 is connected to the first receiving tank 8 and the second receiving tank 9, and the second receiving tank 9 is connected to the adsorption device 10.

[0013] Furthermore, the permeate-side outlet of the second membrane separation system 11 is connected to the inlet of the adsorption device 10, forming a reflux.

[0014] Furthermore, the first membrane separation system 4 consists of multiple sets of acid-resistant membrane modules connected in series or parallel. The membrane material of the acid-resistant membrane modules is one or more composite membrane materials selected from polyamide (PA), polysulfonamide (PSA), or polyethyleneimine (PEI). It can filter and remove some anions, cations, and particulate matter from hydrofluoric acid wastewater. The acid-resistant membrane can be prepared using any of the existing technologies such as interfacial polymerization, phase inversion, or surface modification.

[0015] Furthermore, the adsorption device 10 is filled with an acid-resistant adsorbent, which is a chelating resin.

[0016] Furthermore, the second membrane separation system 11 includes multiple sets of acid-resistant metal ion removal membrane modules connected in series or parallel, wherein the membrane material of the acid-resistant metal ion removal membrane modules is polytetrafluoroethylene (PTFE). This further removes trace metal ions and particulate impurities from hydrofluoric acid wastewater.

[0017] Furthermore, the inner walls of the distillation unit 1, the first membrane separation system 4, the adsorption unit 10, and the second membrane separation system 11 are lined with anti-corrosion material layers, which are PTFE or PFA. All parts of the piping system, heat exchangers, circulating pumps, storage tanks, and other components that come into contact with materials are also lined with anti-corrosion material layers, which are PTFE or PFA.

[0018] Furthermore, the product outlet is connected to product tank 12, which is also equipped with a nitrogen inlet and a hydrofluoric acid concentration detector. This ensures the product's cleanliness and prevents contamination, while simultaneously detecting changes in the hydrofluoric acid concentration.

[0019] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0020] (1) This utility model proposes a multi-step concentration and purification system that combines distillation, adsorption and membrane separation. The distillation column enters two receiving tanks through different temperature gradients to achieve the purpose of concentrating hydrofluoric acid. The adsorption and membrane separation system can effectively remove metal ions and particulate impurities in hydrofluoric acid waste liquid and ultimately achieve the purpose of recycling electronic-grade hydrofluoric acid.

[0021] (2) The membrane material used in the first membrane separation system of this utility model has excellent chemical stability and corrosion resistance. For example, the polysulfonamide membrane has a strong conjugation effect in its molecular structure, which makes it less susceptible to proton attack and thus exhibits excellent acid resistance, making it more suitable for treating waste liquid containing hydrofluoric acid. In addition, the removal of metal ions can be achieved by using the pore size sieving and surface chemical properties of the membrane: for example, the polyamide membrane achieves the adsorption and removal of metal ions by forming coordination bonds with metal ions through polyamide groups, while the polyethyleneimine membrane can effectively remove metal ions through electrostatic and coordination effects.

[0022] (3) In the second membrane separation system of this utility model, trace metal ions in hydrofluoric acid are further removed by acid-resistant PTFE membrane material, which improves the purity of the product and enables it to achieve the purpose of electronic grade hydrofluoric acid recycling. It can also remove trace particulate impurities that may occur during the adsorption process, ensuring the purity and reliability of the final product.

[0023] (4) The distillation device, adsorption tower and membrane module, pipeline, and delivery pump in this utility model all adopt a corrosion-resistant inner structure. Through special material selection and process design, not only is the durability and corrosion resistance of the equipment improved, but also the efficiency and feasibility of the entire device and method in treating hydrofluoric acid waste liquid are ensured, providing an innovative, environmentally friendly and economical solution for the purification and recycling of waste acid in the electronics industry. Attached Figure Description

[0024] Figure 1 This utility model relates to a purification and recovery device for hydrofluoric acid waste liquid in the electronics industry.

[0025] Wherein: 1 is a distillation unit, 2 is a reboiler, 3 is a condenser, 4 is a first membrane separation system, 5 is a second condenser, 6 is a first condenser, 7 is a vacuum pump, 8 is a first receiving tank, 9 is a second receiving tank, 10 is an adsorption unit, 11 is a second membrane separation system, and 12 is a finished product collection tank. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description, in conjunction with embodiments, is provided to enable those skilled in the art to fully understand the technical content of this utility model. It should be understood that the following embodiments are for further explanation of this utility model and should not be construed as limiting the scope of protection of this utility model. Non-essential improvements and adjustments made by those skilled in the art based on the above description of this utility model are all within the scope of protection of this utility model. Unless otherwise specified, the raw materials used in this utility model are commercially available products. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0027] like Figure 1 The device shown is a purification and recovery apparatus for hydrofluoric acid waste liquid in the electronics industry, comprising a distillation unit 1, a first membrane separation system 4, an adsorption unit 10, and a second membrane separation system 11 arranged sequentially.

[0028] The top outlet of the distillation unit 1 is connected to the first membrane separation system 4. The permeate-side outlet of the first membrane separation system 4 is connected to the adsorption unit 10 via the first condenser 6. The permeate-side outlet of the second membrane separation system 11 is connected to the product outlet.

[0029] The bottom of the distillation apparatus 3 is provided with a nitrogen inlet.

[0030] The top outlet of the distillation unit 1 is connected to the first membrane separation system 4 via a condenser 3.

[0031] The reflux outlet of the first membrane separation system 4 is connected to the inlet of the distillation unit 1 via the second condenser 5, forming a reflux.

[0032] The outlet of the first condenser 6 is connected to the first receiving tank 8 and the second receiving tank 9, and the second receiving tank 9 is connected to the adsorption device 10.

[0033] The permeate-side outlet of the second membrane separation system 11 is connected to the inlet of the adsorption device 10, forming a reflux.

[0034] The first membrane separation system 4 consists of multiple sets of acid-resistant membrane modules connected in series or parallel, and the membrane material of the acid-resistant membrane modules is polyamide. It can filter and remove some anions, cations, and particulate matter from hydrofluoric acid waste liquid. The acid-resistant membrane can be prepared by any of the existing technologies such as interfacial polymerization, phase inversion, or surface modification.

[0035] The adsorption device 10 is filled with an acid-resistant adsorbent, which is a chelating resin.

[0036] The second membrane separation system 11 includes multiple sets of acid-resistant metal ion removal membrane modules connected in series or parallel. The membrane material of the acid-resistant metal ion removal membrane modules is polytetrafluoroethylene. It can further remove trace metal ions and particulate impurities from hydrofluoric acid waste liquid.

[0037] The inner walls of the distillation unit 1, the first membrane separation system 4, the adsorption unit 10, and the second membrane separation system 11 are lined with a corrosion-resistant material layer, which is PTFE. Corrosion-resistant material layers, which are also provided in the piping systems, heat exchangers, circulating pumps, storage tanks, and other parts that come into contact with materials, are also lined with PTFE or PFA.

[0038] The product outlet is connected to product tank 12, which is also equipped with a nitrogen inlet and a hydrofluoric acid concentration detector. This ensures the product's cleanliness and prevents contamination, while simultaneously detecting changes in the hydrofluoric acid concentration.

[0039] The core feature of this device lies in the combination of multi-stage separation and adsorption treatment. The distillation unit first heats the water collected from the top of the column and sends it to the first receiving tank, then continues heating it to the second receiving tank to concentrate and remove hydrofluoric acid. The first membrane separation system uses an acid-resistant membrane to further filter impurities, while the adsorption unit removes metal ions by filling it with an acid-resistant adsorbent. The second membrane separation system uses an acid-resistant metal ion removal membrane to further purify the hydrofluoric acid. Through this multi-stage separation and adsorption treatment, water, impurities, and metal ions in hydrofluoric acid waste liquid can be effectively removed, achieving efficient purification and recovery of hydrofluoric acid.

[0040] By installing an anti-corrosion material layer on the material contact parts of the hydrofluoric acid waste liquid purification and recovery device, the corrosion of the equipment by hydrofluoric acid is effectively prevented, extending the service life of the equipment and ensuring the stability and safety of the purification and recovery process. The anti-corrosion layer material is PTFE or PFA, which have excellent corrosion resistance and can be used for a long time in highly corrosive environments.

[0041] By using multiple sets of acid-resistant membrane modules connected in series or parallel, efficient removal and purification of impurities in hydrofluoric acid wastewater is achieved. The membrane materials of the acid-resistant membrane modules are polyamide and other materials, which have good acid resistance and can operate stably in a hydrofluoric acid environment. By connecting them in series or parallel, the number and arrangement of the membrane modules can be adjusted according to specific needs to improve treatment efficiency and purification effect.

[0042] The adsorption device is internally filled with an acid-resistant adsorbent, specifically a chelating resin. This chelating resin possesses excellent acid resistance and adsorption capacity, effectively removing impurities from hydrofluoric acid wastewater. Using this adsorbent improves the purity of hydrofluoric acid, meeting the electronics industry's demand for high-purity hydrofluoric acid. A fluid distributor is installed at the top of the adsorption device, connected to the inlet. The fluid distributor ensures that the hydrofluoric acid wastewater entering the adsorption device is evenly distributed on the adsorbent material, thereby improving the adsorption effect. This technology effectively solves the problem of uneven distribution of hydrofluoric acid wastewater within the adsorption device, improving the efficiency and effectiveness of the adsorption process and ensuring better purification and recovery of the hydrofluoric acid wastewater.

[0043] The membrane material of the acid-resistant demetallization membrane module is polytetrafluoroethylene (PTFE). Based on its excellent chemical stability and mechanical strength, this material can be used for a long time in a strong acid environment without degradation or performance decline.

[0044] The outlet on the permeate side of the first membrane separation system is connected to the inlet of the distillation unit. This allows incompletely separated hydrofluoric acid waste liquid to be returned to the distillation unit for further treatment, improving separation efficiency. The outlet on the permeate side of the second membrane separation system is connected to the inlet of the adsorption unit. This allows incompletely removed metal ions and other impurities to be fed back into the adsorption unit for further treatment, ensuring the purity of the final product. Through these two connections, the entire system can more efficiently circulate and treat hydrofluoric acid waste liquid, achieving higher recovery rates and purity.

[0045] A nitrogen protection system, through a continuous supply of nitrogen, creates an inert gas environment, effectively isolating the hydrofluoric acid from oxygen and moisture in the air, preventing reactions between hydrofluoric acid and airborne components, and reducing its volatilization and corrosion. The hydrofluoric acid concentration detector can employ various types of sensors, such as optical and electrochemical sensors, to detect the concentration of hydrofluoric acid in real time and transmit the data to the control system. The control system can automatically adjust the nitrogen supply based on the detection results to ensure the hydrofluoric acid concentration remains within a predetermined range. The combined use of the nitrogen protection system and the hydrofluoric acid concentration detector effectively solves the pollution problem caused by hydrofluoric acid contact with air, improves the purity and quality of recovered hydrofluoric acid, reduces environmental pollution, lowers production costs, and increases resource recycling rates. Compared with existing technologies, the technical solution provided in this application offers higher safety and reliability, better meeting the high purity requirements of the electronics industry for hydrofluoric acid.

[0046] When using the above-mentioned device, the operation is as follows:

[0047] Step S1: 10%wt hydrofluoric acid waste liquid is fed into a distillation unit. The operating absolute pressure is 0.02 MPa, the reflux ratio is 0.5, the top temperature is 60°C, and the bottom temperature is 70°C. A condenser is installed at the top of the column. The liquid enters the distillation column to form reflux, while the gas phase enters the first membrane separation system under vacuum. The permeate side is condensed and then enters the first and second receiving tanks. The first batch collected into the first receiving tank is ultrapure water, and the later batch collected into the second receiving tank is an aqueous solution of hydrofluoric acid. This step can concentrate the hydrofluoric acid solution and remove most of the impurities.

[0048] Step S2: The hydrofluoric acid solution after step S1 is further fed into an adsorption device, which is equipped with an acid-resistant PHA chelating resin as an adsorbent to remove a small portion of the metal ions in the solution.

[0049] Step S3: The hydrofluoric acid solution processed in step S2 is finally sent to the second membrane separation system. Under the action of a special acid-resistant metal ion removal membrane, trace metal ions and particulate impurities in the hydrofluoric acid are further removed. The final metal ion removal rate is ≥99.5%. Hydrofluoric acid product is collected on the permeate side, and 37.2%wt hydrofluoric acid product is collected on the permeate side, achieving the purpose of recycling electronic-grade hydrofluoric acid.

[0050] The analytical results of the electronic-grade hydrofluoric acid products in the examples are shown in Table 1.

[0051] index E2 E3 raw material Example Particles (≥0.5μm) pcs / mL ≤50 ≤25 2286000 25 Particles (≥1.0μm) pcs / mL ≤25 ≤10 35840000 18 <![CDATA[Fluorosilicate (SiF4 2- ) mg / kg]]> ≤50 ≤50 10365 35.0 <![CDATA[Nitrate (NO3 - ) mg / kg]]> ≤3 ≤3 5.6 1.2 <![CDATA[Sulfate (SO4) mg / kg]]> ≤5 ≤0.5 4.3 0.2 <![CDATA[Phosphate (PO4 3- ) mg / kg]]> ≤1 ≤0.5 2.6 0.1 Arsenic (As) μg / kg ≤50 ≤10 160.5 3.0 Gold (Au) μg / kg ≤20 ≤10 10.8 0.5 Silver (Ag) μg / kg ≤20 ≤10 10.3 0.04 Boron (B) μg / kg ≤20 ≤10 6200 0.8 Barium (Ba) μg / kg ≤50 ≤10 9.6 0.05 Bismuth (Bi) μg / kg ≤50 ≤10 10.2 0.04 Cadmium (Cd) μg / kg ≤20 ≤10 20 0.5 Cobalt (Co) μg / kg ≤50 ≤10 7.6 0.5 Chromium (Cr) μg / kg ≤20 ≤10 5.8 0.7 Copper (Cu) μg / kg ≤50 ≤10 60 0.6 Germanium (Ge) μg / kg ≤50 ≤10 5.6 0.5 Indium (In) μg / kg ≤50 ≤10 20.5 0.2 Lithium (Li) μg / kg ≤10 ≤5 20 0.3 Magnesium (Mg) μg / kg ≤20 ≤10 83 0.4 Manganese (Mn) μg / kg ≤20 ≤10 10 1.3 Molybdenum (Mo) μg / kg ≤20 ≤10 8.5 1.5 Sodium (Na) μg / kg ≤50 ≤10 107700 1.8 Nickel (Ni) μg / kg ≤20 ≤10 82 0.6 Lead (Pb) μg / kg ≤20 ≤10 897 1.5 Platinum (Pt) μg / kg ≤50 ≤10 5.6 0.6 Antimony (Sb) μg / kg ≤20 ≤10 8.5 0.4 Tin (Sn) μg / kg ≤20 ≤10 9.5 0.5 Titanium (Ti) μg / kg ≤50 ≤10 16 1.8 Vanadium (V) μg / kg ≤50 ≤10 5.4 0.5

Claims

1. A purification and recovery device for hydrofluoric acid waste liquid in the electronics industry, characterized in that, It includes a distillation unit (1), a first membrane separation system (4), an adsorption unit (10), and a second membrane separation system (11) arranged in sequence. The top outlet of the distillation unit (1) is connected to the first membrane separation system (4), the permeate outlet of the first membrane separation system (4) is connected to the adsorption unit (10) through the first condenser (6), and the permeate outlet of the second membrane separation system (11) is connected to the product outlet. The bottom of the distillation apparatus (1) is provided with a nitrogen inlet.

2. The purification and recovery device for hydrofluoric acid waste liquid in the electronics industry according to claim 1, characterized in that, The top outlet of the distillation unit (1) is connected to the distillation unit (1) and the first membrane separation system (4) via a condenser (3).

3. The purification and recovery device for hydrofluoric acid waste liquid in the electronics industry according to claim 1, characterized in that, The osmotic side outlet of the first membrane separation system (4) is connected to the inlet of the distillation unit (1) via the second condenser (5).

4. The purification and recovery device for hydrofluoric acid waste liquid in the electronics industry according to claim 1, characterized in that, The outlet of the first condenser (6) is connected to the first receiving tank (8) and the second receiving tank (9), and the second receiving tank (9) is connected to the adsorption device (10).

5. The purification and recovery device for hydrofluoric acid waste liquid in the electronics industry according to claim 1, characterized in that, The permeate side outlet of the second membrane separation system (11) is connected to the inlet of the adsorption device (10).

6. The purification and recovery device for hydrofluoric acid waste liquid in the electronics industry according to claim 1, characterized in that, The first membrane separation system (4) consists of multiple sets of acid-resistant membrane components connected in series or in parallel. The membrane material of the acid-resistant membrane components is one or more composite membrane materials selected from polyamide, polysulfonamide or polyethyleneimine.

7. The purification and recovery device for hydrofluoric acid waste liquid in the electronics industry according to claim 1, characterized in that, The adsorption device (10) is filled with an acid-resistant adsorbent, which is a chelating resin.

8. The purification and recovery device for hydrofluoric acid waste liquid in the electronics industry according to claim 1, characterized in that, The second membrane separation system (11) includes multiple sets of acid-resistant demetallization membrane modules connected in series or in parallel, wherein the membrane material of the acid-resistant demetallization membrane modules is polytetrafluoroethylene.

9. The purification and recovery device for hydrofluoric acid waste liquid in the electronics industry according to claim 1, characterized in that, The inner walls of the distillation apparatus (1), the first membrane separation system (4), the adsorption apparatus (10), and the second membrane separation system (11) are provided with an inner anti-corrosion material layer, which is PTFE or PFA.

10. The purification and recovery device for hydrofluoric acid waste liquid in the electronics industry according to claim 1, characterized in that, The product outlet is connected to the product tank (12), which is also equipped with a nitrogen inlet and a hydrofluoric acid concentration detector.

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