JP7523820B2 - Separation and purification method for purifying industrial-grade high-concentration HF to electronic-grade FTrPSA - Google Patents

Description

This invention is a creation related to the purification and purification of electronic-level HF using industrial-level high-concentration hydrogen fluoride (HF) as a raw material. More specifically, this invention is a creation related to a separation and purification method for refining industrial-level high-concentration HF to electronic-level FTrPSA (full-temperature swing pressure adsorption).

Hydrogen fluoride (HF) is a basic raw material in fluorine chemistry and can be used in the production of organic fluorine, inorganic fluoride salts and other fluorine-containing catalytic agents, fluorine silicate and other fields. HF is increasingly being used in the field of organic fluorine, such as refrigerants, surfactants, fluorine rubber, fluorine paints, fluorine-containing resins, fluorine-containing pesticides, high-purity fluorine resins and pharmaceutical intermediates. At present, with the development of the semiconductor industry, ultra-high purity electronic level HF (gas and liquid) has been widely used in the cleaning, etching and chemical vapor deposition processes of integrated circuit (IC) and very large scale integrated circuit (VLSI) wafers, and is one of the key basic chemical materials in the manufacturing process of the microelectronics industry. It can also be used as an analytical reagent to prepare high-purity fluorine-containing chemicals and semiconductor materials.

At present, the preparation and extraction of industrial high purity HF mainly uses industrial high concentration HF as raw material, and adopts distillation/rectification and membrane separation as the main purification method, including rectification, distillation, subboiling distillation, vacuum distillation, gas absorption, microfilter, ultrafiltration, nanofiltration and various configurations. In these traditional purification processes, the impurities in the raw material (liquid/gas) are fractionated and purified and removed by utilizing the difference in volatility (boiling point), solubility or molecular size between each fraction of the raw material and HF at different temperatures, so that anhydrous HF (AHF) products with the equivalent purity can be obtained. The main impurity fractions in the raw material are fluorosilicic acid (H ₂ SiF ₆ ), water (H ₂ O), chlorides (mainly hydrogen chloride HCl), phosphides (P), metal oxides (MeO), metal ions and solid granules (SS), etc. Electronic level HF products are classified into EL (general electronic level), UP (ultra pure), UPS (ultra high purity), and UPSS (ultra high purity), and the Semiconductor Industry International (SEMI) has also established a standard corresponding to the SEMI-C/S level, which corresponds to the UPS/UPSS level. For example, the UP electronic level HF (liquid) index commonly used in China is that the H ₂ SiF ₆ content is less than 100 ppm, chloride (Cl) is less than 5 ppm, P is less than 1 ppm, MeO/Me+ is less than 10 ppb, and SS (≧1 μm) is less than 25 units (pieces)/ml. MeO/Me+ is especially water-soluble arsenic (As), magnesium (Mg), calcium (Ca), sodium (Na) and potassium (K) and other MeO/Me+ impurities, which must be thoroughly removed. Otherwise, it will have a serious impact on the performance of semiconductor wafers. The electronic level HF liquid as semiconductor wafer cleaning agent or wet etching has various levels of HF content, for example 49%, and the rest is deionized water. Therefore, the fluorite method or fluorosilicic acid method is generally adopted in industry, and after rectification and membrane filtration in the production process of preparing non-aqueous HF (AHF), pure AHF gas with a purity of 99.9% can be obtained. After absorption with deionized water, the method of controlling shower density, gas-liquid ratio and membrane filtration can be adopted to further purify electronic level hydrofluoric acid to obtain electronic level HF liquid product. However, in the rectification process, due to the mutual solubility of water, HF, and other impurities generated from the fluorite or _{fluorosilicic} acid process itself, such as sulfuric acid ( _H2SO4 ), sulfur dioxide ( _SO2 ), hydrogen chloride (HCl), silicon tetrafluoride ( _SiF4 ), ammonia ( _NH3 ) and carbon dioxide ( _CO2 ), and the constraint of phase equilibrium imposed on the rectification separation, these impurities and HF cannot be completely separated, so that the obtained pure AHF gas still contains a relatively large amount of impurity fraction, and therefore it is also very difficult to remove trace or very trace amounts of impurity fraction by subsequent purification in the processes of deionized water absorption, shower density and gas-liquid ratio control, membrane filtration, etc. Therefore, it is very important to control the purity of the pure AHF product obtained in the production process of preparing AHF from the fluorite or fluorosilicic acid process. Therefore, if 95-99% industrial-level HF or AHF feed gas is directly subjected to rectification, distillation, sub-distillation or special rectification, the impurity concentration is too low, and the cost of rectification or distillation is very high. Although the difference in boiling point between the impurity fraction and HF is relatively large, water affects the distribution of mass transfer of each impurity fraction in water, so that the rectification or distillation has a severe limit on the phase equilibrium, and the purification depth is far from the requirement of electronic level.

It has been reported that the adsorption method can be used to purify HF, and the adsorbent is mainly an alkaline metal fluoride, and the chemical reaction between the metal fluoride and HF occurs at a relatively low temperature to selectively perform chemical adsorption to form a metal fluoride-HF complex. The decomposition reaction of the complex is carried out at a relatively high temperature to adsorb and desorb HF from the adsorbent, and other impurities can be separated and purified without the selectivity of the adsorbent. Most of the process situations in which this chemical adsorption method is applied are when preparing products such as fluorochloroalkanes (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and sulfuryl fluoride (SO ₂ F ₂ ) through fluorination reactions, and the reaction mixture gas generated by the reaction can selectively adsorb, separate, and recover HF, so the effect is better, but the loss rate of the adsorbent is large. For crude HF or pure HF obtained by the fluorite method or fluorosilicic acid method, which contains water, sulfuric acid, or _SiF4 , the adsorbent reacts chemically with the fraction of impurities such as water, causing the adsorbent to powder, and the effect of the adsorbent is significantly lost, making it impossible to effectively remove impurities by deep dehydration. What is particularly important is that the alkaline metal or metal ion on the adsorbent chemically reacts with HF and is taken into the HF gas itself, making the subsequent HF purification difficult. Therefore, the chemical adsorption method cannot be effectively applied to the AHF process prepared by the fluorite method or fluorosilicic acid method.

This is also one of the main reasons why China can only produce low-quality electronic-level AHF products at present, and is one of the important reasons why Japan used its technological superiority to restrict the export of electronic-level AHF to Korea in the trade dispute over electronic-level semiconductor chemicals that arose between Japan and Korea. Japan is one of the very few countries internationally that has the technology to prepare AHF with a purity of 99.9999% to 99.99999999% (6N to 12N).

The object of the present invention is to provide a separation and purification method for purifying industrial-level high-concentration HF into electronic-level FTrPSA (full temperature range-pressure swing adsorption). Full temperature range-pressure swing adsorption (FTrPSA) is a method based on pressure swing adsorption (PSA) that can be combined with various separation technologies. Each fraction (HF is the useful fraction _H2O , _H2SO4 , _SO2 , _SiF4 , _NH3 , _CO2 , _H2SiF ) in industrial-level AHF (gas) can be separated and purified _. The main impurity fraction of the HF _-1000 (H2SO4 and trace amounts of HCl, water-soluble Me+ ions and SS particles) is a two-stage medium-temperature pressure swing adsorption process that utilizes the differences in adsorption/rectification/membrane separation coefficients and physicochemical properties under different pressures and temperatures, and combines HF with rectification/membrane separation. The adsorption and desorption in the medium-temperature pressure swing adsorption process can be easily separated and purified through repeated operations of consistency and equilibrium, thereby realizing the production of electronic-level HF products.

The technical ideas adopted by this invention are as follows:

In the separation and purification method for purifying industrial-level high-concentration HF to electronic-level FTrPSA, the raw material gas is industrial-level high-concentration hydrogen fluoride (HF) gas produced in the process of producing anaqueous hydrogen fluoride (AHF) prepared by the fluorite method or the fluorosilicic acid method, HF having a content of 95-99% (v/v), sulfuric acid (H ₂ SO ₄ ), water (H ₂ O), sulfur dioxide (SO ₂ ), silicon tetrafluoride (SiF ₄ ), ammonia (NH 3 ), fluorosilicic acid (H ₂ SiF ₆ ), carbon dioxide (CO ₂ ), chloride (calculated as HCl), metal ions (Me+), fine particles (SS) and other impurity fractions, where Me+ is mainly water-soluble sodium (Na), magnesium (Mg), calcium (Ca) and arsenic (As) ions, the diameter of the SS particles is greater than 1 micrometer (μm), the temperature is 20-60°C, and the pressure is normal pressure or low pressure, and the process includes the following steps:
(1) The raw gas is subjected to cold and heat exchange between 50-80°C, and then pressurized to 0.2-0.3MPa, and then enters into the medium temperature pressure swing adsorption process consisting of two-stage pressure swing adsorption (PSA). Each stage pressure swing adsorption is composed of at least two or more adsorption towers, at least one adsorption tower is in the adsorption process, and the remaining adsorption towers are in the desorption process of reverse depressurization or vacuum evacuation, pressurization or final filling and other different stages. The raw gas enters from the bottom of the first stage PSA (1 ^# PSA) adsorption tower, the operating pressure of 1 ^# PSA is 0.2-0.3MPa, and the operating temperature is 50-80°C. The non-adsorbed phase gas flowing out from the top of the adsorption tower in the adsorption process is pure HF gas. The non-condensed gas after condensation is microfiltered, and after absorbing deionized water, the obtained HF aqueous solution with a concentration of 40-49% is exported as a general electronic EL level hydrofluoric acid product. The pure HF formed after condensation enters the next process, which is membrane separation, and is in the desorption process. 1 ^# The desorbed gas flowing out from the bottom of the PSA adsorption tower is pressurized and subjected to cold and heat exchange, and then enters from the bottom of the second stage PSA (2 ^# PSA) adsorption tower. The operating pressure of the 2 ^# PSA adsorption tower is 0.2-0.3 MPa, and the operating temperature is 50-80°C. The non-adsorbed intermediate gas flowing out from the top of the 2 ^# PSA adsorption tower in the adsorption process is mixed with the raw material gas and returns to the 1 ^# PSA adsorption tower. The desorbed gas flowing out from the bottom of the 2 ^# PSA adsorption tower is a concentrated gas, which enters the subsequent ammonia water decarbonization process and further recovers the useful fraction, this is medium temperature pressure swing adsorption.
(2) The pure HF liquid formed by condensation from the medium temperature pressure swing adsorption process is pressurized to 1.0-1.6 MPa and the temperature is 50-80°C, and enters into a first or second class inorganic ceramic membrane or stainless steel membrane separation system, the membrane pore size is less than 1 micrometer, the purified pure HF liquid flows out from the side that has permeated the membrane, and the content of SS particles with a diameter of more than 1 μm is less than 25 (pieces) units/milliliter (Ea/ml) and enters into the next process, HF rectification, where the SS particle concentrate is concentrated on the side that has not permeated the membrane, cooled and precipitated, after which the SS particles are removed, the liquid is heated and pressurized, and then returned to the membrane separation system, and the useful fraction is further recovered. Membrane separation.
(3) The purified pure HF liquid from the membrane separation process enters the rectification tower of the HF rectification process. The rectification tower in this process adopts a two-stage rectification configuration, with the purified pure HF liquid entering from the top of the lower rectification or the bottom of the upper rectification. The light fraction impurity gas removed from the top of the upper rectification tower returns to the subsequent exhaust gas absorption process. The non-condensable gas formed after the distillate at the bottom of the upper rectification or the top of the lower rectification is AHF gas, with a purity of more than 99.99%, which can be directly used as electronic UP or USP level AHF product gas. The liquid formed after condensation is used as a recycle for the upper or lower rectification. The non-condensable gas formed after the bottom fluid of the impurity fraction containing a small amount of heavy fraction distilled from the bottom of the lower rectification is returned to the temperature change pressure adsorption process, and further useful fraction is recovered. The liquid formed after condensation is used as an absorbent for the next process of ammonia water decarbonization, HF rectification.
(4) The concentrated gas from the medium temperature pressure swing adsorption process is pressurized to normal pressure or slightly overpressure, and then enters into the liquid formed after the condensation of the distillate from the lower stage of the ammonia water, sulfuric acid and HF rectification process, and is mixed with the ammonia water decarbonization absorption tower as the absorbent according to the ratio, and the mixed solution of ammonium bicarbonate and ammonium bifluoride formed from the bottom of the absorption tower is discharged, and used as the direct fluorosilicic acid method to prepare the return material or pre-mixed reactant in the AHF production process, ammonia water decarbonization.

Furthermore, the membrane separation system in step (2) can use a microfilter membrane or an ultrafiltration membrane as the membrane module.

In addition, the light impurity gas distilled from the top of the upper rectification tower in the HF rectification process is mixed with the non-condensable gas from the top of the ammonia water decarbonization absorption tower and enters the exhaust gas absorption tower using sulfuric acid as an absorbent, forming a fluorosilicic acid solution from the bottom of the absorption tower, which is discharged as a raw material and can be directly returned to the raw material circulation use in the non-aqueous hydrogen fluoride AHF production process prepared by the fluorosilicic acid method, and also includes an exhaust gas absorption process in which the non-condensable gas flowing out from the top of the absorption tower is directly discharged as exhaust gas.

Furthermore, the adsorption towers in the medium temperature pressure swing adsorption process are loaded with activated aluminum oxide, silica gel and molecular sieves, and the weight ratio of aluminum oxide:silica gel:molecular sieve in the adsorbent composition loaded in the 1 ^# PSA adsorption tower is (4-6):(2-4):(1-3), and the weight ratio of aluminum oxide:silica gel:molecular sieve in the adsorbent composition loaded in the 2 ^# PSA adsorption tower is (3-5):(1-3):(3-5).

The loading quantity and distribution of the three types of adsorbents are determined by the HF concentration of the feed gas and the impurity fraction content, and the loading quantity distribution of the adsorbents in the two-stage PSA adsorption tower also differs.

In addition, in exhaust gas absorption, the light impurity gas distilled from the top of the upper rectification tower in the HF rectification process is mixed with the non-condensable gas from the top of the ammonia water decarbonization absorption tower, enters the exhaust gas absorption tower using sulfuric acid as an absorbent, forms a fluorosilicic acid solution from the bottom of the absorption tower, and is discharged as a raw material, which can be directly returned to the raw material circulation use in the AHF production process prepared by the fluorosilicic acid method, and the non-condensable gas flowing out from the top of the absorption tower is directly discharged as exhaust gas.

Furthermore, the pure HF liquid inlet end of the above-mentioned HF rectification process is installed at the bottom of the upper stage or the top of the lower stage, depending on the content of the main impurity fractions, namely _H2O , _H2SO4 , _SO2 , _SiF4 , _NH3 , _CO2 , and _{H2SiF6 ,} contained in the raw _gas .

In addition, the non-condensable gas formed after the distillate from the bottom of the upper rectification or the top of the lower rectification in the above-mentioned HF rectification process is AHF gas, with a purity of more than 99.99%, which is further condensed to form AHF liquid, which then enters into the fluorine exchange resin to further remove Me+ and form AHF liquid of UPSS electronic level, which can be arbitrarily mixed with deionized water to form HF solution, which can meet the needs of various concentrations in the semiconductor industry.

The beneficial effects of the present invention compared to the prior art are as follows:

1) The present invention uses high-concentration HF gas produced during the AHF production process prepared by the traditional fluorite method or fluorosilicic acid method as a raw material, and prepares gas from the raw material to EL/UP/UPS to UPSS electronic level AHF gas or liquid required by the semiconductor industry, thereby resolving the problems that AHF purification faces, such as phase equilibrium limitations in traditional separation processes such as rectification, distillation, absorption, or chemical adsorption, and the short service life of adsorbents. This fills a gap in the technical field.

2) The present invention utilizes the differences in the adsorption/coagulation/rectification/membrane separation coefficients and physicochemical properties of each fraction in the raw gas (HF is a useful fraction, the rest are impurity fractions) under different pressures and temperatures, and employs a two-stage medium-temperature pressure swing adsorption process that mainly combines coagulation, membrane separation and HF rectification, thereby facilitating the consistency of adsorption and desorption in the medium-temperature pressure swing adsorption process and the circulation operation of equilibrium, thereby achieving separation and purification, and deep dehydration and removal of HF.

3) The present invention overcomes the problem that the adsorbent loss rate is large in the frequent cycle operation process of adsorption and desorption, which is achieved by the chemical adsorption method of the prior art, in which HF and an adsorbent undergo a chemical (chelating) reaction at low temperatures to adsorb, while a decomposition reaction occurs at high temperatures to desorb. At the same time, for crude HF or pure HF obtained by the fluorite method or fluorosilicic acid method containing water, sulfuric acid, or _SiF4 , the adsorbent in the prior art chemical adsorption also undergoes chemical reactions with impurity fractions such as water, which causes the adsorbent to become powdered and lose its effectiveness significantly, making it impossible to efficiently perform deep dehydration and removal, whereas the present invention adopts medium temperature variable pressure physical adsorption, which can avoid such phenomena and extend the service life of the adsorbent.

4) The present invention can avoid the problems that arise in the simple rectification process in the AHF purification process, such as large fluctuations in temperature in the middle of the rectification tower, the temperature at the bottom of the tower not meeting the requirements, and the relatively large HF concentration fluctuations resulting in unfavorable rectification effects. The present invention first adopts a two-stage PSA to first remove most of the main heavy fraction impurities, reducing the fluctuations in HF concentration entering the HF rectification process, and adopts an upper and lower two-stage rectification method, thereby realizing deep dehydration and removal for the preparation of AHF products, obtaining electronic-level AHF products and at the same time obtaining an HF aqueous solution with a concentration of 40-49%.

5) The present invention produces electronic level AHF, and at the same time, the materials from the mid-temperature variable pressure adsorption and HF rectification processes are returned to the front-end condensation or ammonia water decarbonization processes, etc., and HF is further recovered, so that the yield of AHF products exceeds 90%, and the target of exhaust gas emission is achieved through the exhaust gas absorption process.

FIG. 2 is a process diagram of the first embodiment of the present invention. FIG. 4 is a process diagram of Example 2 of the present invention.

In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be described in more detail. It should be noted that the specific examples described in this application are only used to explain the present invention and are not intended to limit the present invention. That is, the examples described are only some of the examples of the present invention and are not all of the examples.
Example 1
As shown in FIG. 1, in the separation and purification method for refining industrial-level high-concentration HF to electronic-level FTrPSA, the raw material gas is industrial-level high-concentration hydrogen fluoride (HF) gas generated in the production process of anaqueous hydrogen fluoride (AHF) prepared by the fluorite method and the fluorosilicic acid method. The water content (H ₂ O) of the HF with a content concentration of 98% (v/v) is 1%, and the other impurities are sulfur dioxide (SO ₂ ), silicon tetrafluoride (SiF ₄ ), ammonia (NH ₃ ), fluorosilicic acid (H ₂ SiF ₆ ), carbon dioxide (CO ₂ ), chloride (calculated as HCl), the total amount being 0.9-1.0%, the concentration of metal ions (Me+) mainly consisting of sodium (Na), magnesium (Mg), calcium (Ca), and arsenic (As) ions is at an extremely low ppm level, the fine particles (dss≧1 μm) are greater than 100, the temperature is 20-30° C., and the pressure is normal pressure. The specific implementation steps are as follows:
(1) The raw gas is subjected to heat and cold exchange between 60 and 70°C, and then the pressure is increased to 0.2 to 0.3 MPa by the suction blower. Then, it enters the medium temperature pressure swing adsorption process in the two-stage pressure swing adsorption (PSA) composition. There are three first-stage PSA (1 ^# PSA) adsorption towers, one of which is adsorbed in the adsorption tower, and the other two adsorption towers are depressurized and evacuated. In the process of filling the raw gas and desorption at the final filling, the raw gas enters from the bottom of the 1 ^# PSA adsorption tower, and the 1 ^# The operating pressure of PSA is 0.2-0.3MPa, and the operating temperature is 60-70℃. The non-adsorbed gas flowing out from the top of the adsorption tower in the adsorption process is pure HF gas. The non-adsorbed gas after condensation is filtered through precision filtration to absorb deionized water, and the resulting 49% HF aqueous solution is exported as a general electronic level hydrofluoric acid product. The pure HF liquid formed after condensation enters the next process, membrane separation. The desorbed gas flowing out from the bottom of the 1 ^# PSA adsorption tower in the desorption process enters the bottom of the second stage PSA (2 ^# PSA) adsorption tower after pressure increase and cold heat exchange. The 2 ^# PSA is composed of three adsorption towers, one of which is in the adsorption state from start to finish, and the other two adsorption towers are respectively in the depressurization and evacuation, the pure HF gas pressure-filling and final charging desorption state, and the adsorption and desorption circulation operation. 2 ^# The operating pressure of the PSA adsorption tower is 0.2-0.3 MPa, the operating temperature is 60-70°C, and the non-adsorbed intermediate gas flowing out from the top of the 2 ^# PSA adsorption tower in the adsorption state is mixed with the raw material gas and returned to the 1 ^# PSA, and the gas flowing out from the 2 ^# PSA adsorption tower is a concentrated gas, which then enters the subsequent ammonia water decarbonization process and further recovers the useful fraction, medium temperature variable pressure adsorption.
(2) From the medium temperature pressure change adsorption process, the pure HF liquid formed after condensation is pressurized to 1.6 MPa, and the temperature is 60-70°C, and enters into a first-level inorganic ceramic membrane separation system, the membrane pore size is 0.2-0.4 micrometers, the film material is a zirconia, titanium dioxide and aluminum oxide composite membrane, the content of zirconia and titanium oxide exceeds that of aluminum oxide, and corrosion-resistant tetrafluoroethylene is used as the antiseptic sealing material, and the membrane module that forms a multi-lane internal pressure type flows out the purified pure HF liquid from the membrane permeation side, and the content of SS particles with a diameter of more than 1 μm is less than 25 (pieces) units/milliliter (Ea/ml), and enters into the next process, which is HF rectification, and the SS concentrated liquid is concentrated into the non-membrane permeation side, and after cooling and settling, the SS particles are removed, and the liquid is heated and pressurized, and then returned to the membrane separation system, and the useful fraction is further recovered. Membrane separation.
(3) HF rectification is the purified pure HF liquid from the membrane separation process, which enters the rectification tower of the HF rectification process. The rectification tower in this process adopts an upper and lower two-stage rectification composition. The purified pure HF liquid enters from the top of the lower rectification. The operating temperature of the upper rectification tower is 18-30°C. The light fraction impurity gas distilled from the top of the upper rectification tower is mainly SO ₂ , SiF The bottom distillate of the upper rectification is composed of low boiling point impurity fractions such as ₄ , and returns to the subsequent exhaust gas absorption process. The non-condensable gas formed after condensation from the bottom distillate of the upper rectification is AHF gas, with a purity of more than 99.99%, and can be used as a direct electronic UP or UPS level AHF product gas. The liquid formed after condensation is used as reflux for the upper rectification. The operating temperature of the lower rectification is 20-100°C. The bottom fluid of the impurity fraction distilled from the bottom of the lower rectification, including a small amount of heavy fraction, is formed into a non-condensable gas after condensation and returns to the medium temperature pressure swing adsorption process, and further useful fraction is recovered. The liquid formed after condensation is used as absorbent for the subsequent ammonia water decarbonization process. The operating pressure of the HF rectification is 0.03-0.2Mpa.
(4) The concentrated gas from the medium temperature pressure change adsorption process is pressurized to 0.03-0.2 MPa by the suction blower, and then enters the liquid formed after the condensation of the rectified distillate from the lower stage of the ammonia water, sulfuric acid and HF rectification process, and is mixed with the ammonia water decarbonization absorption tower as the absorbent based on the ratio of 5:3:2, and the ammonium bicarbonate and ammonium bifluoride mixed solution formed is discharged from the bottom of the absorption tower, and the non-condensed gas flowing out from the top of the ammonia water decarbonization absorption tower enters the subsequent exhaust gas absorption process as the return material or pre-mixed reactant in the AHF production process prepared as a direct fluorosilicic acid method.
(5) The light fraction impurity gas distilled from the top of the upper rectification tower in the HF rectification process is mixed with the non-condensable gas from the top of the ammonia water decarbonization absorption tower, enters the exhaust gas absorption tower using sulfuric acid as an absorbent, forms a fluorosilicic acid solution from the bottom of the absorption tower, and is discharged as raw material, and is returned to the circulating use of raw materials in the AHF production process prepared by the fluorosilicic acid method. The non-condensable gas flowing out from the top of the absorption tower is directly discharged as exhaust gas, exhaust gas absorption.
Example 2
2, based on Example 1, the raw gas is high-concentration HF gas from the AHF production process prepared by the fluorite method, and does not contain any impurity fraction of _NH3 or _CO2 , so the ammonia water decarbonization process can be omitted. That is, the concentrated gas from the medium temperature pressure swing adsorption process is returned to the condensation process in the AHF production process prepared by the fluorite method, and the useful fraction is further recovered.
Example 3
Based on Examples 1 and 2, in the above-mentioned medium temperature pressure swing adsorption process, the adsorbent composition ratio loaded in the 1 ^# PSA adsorption tower is aluminum:silica gel:molecular sieve=5:3:2, and the adsorbent composition ratio loaded in the 2 ^# PSA adsorption tower is 4:2:4.

The above-mentioned examples represent specific implementation methods of the present application, and the explanations are more specific and detailed, but they should not be understood as limiting the scope of protection sought by the claims of the present application. Furthermore, a person with ordinary knowledge in the technical field of the present application may make some modifications and improvements based on the premise of the technical ideas of the invention of the present application, all of which fall within the scope of protection of the present application.

Claims (6)

(1) A medium temperature pressure swing adsorption process carried out on a raw gas that has been subjected to cold and heat exchange at a temperature between 50 and 80°C and pressurized to 0.2 to 0.3 MPa,
The intermediate temperature pressure swing adsorption process is composed of two-stage pressure swing adsorption including a first stage PSA and a second stage PSA ;
each of the first stage PSA and the second stage PSA employs at least two or more adsorption columns, at least one of the at least two or more adsorption columns being in an adsorption step and the remaining adsorption columns being in reverse depressurization , evacuation, pressurization , or final filling ;
The feed gas is fed into the bottom of the adsorption tower in the first stage PSA, the operation pressure of the first stage PSA is 0.2-0.3 MPa, and the operation temperature is 50-80° C.;
Pure HF gas is obtained as a non-adsorbed phase gas from the top of the adsorption tower in the adsorption step,
In the pure HF gas, impurities are condensed to obtain pure HF liquid and non-condensable gas, and the non-condensable gas after the condensation is subjected to precision filtration and absorbed in deionized water to obtain an aqueous HF solution having a concentration of 40-49%;
The desorbed gas flowing out from the bottom of the first-stage PSA adsorption tower is pressurized and subjected to cold and heat exchange, and then introduced into the bottom of the second-stage PSA adsorption tower, the operation pressure of the second-stage PSA adsorption tower being 0.2-0.3 MPa and the operation temperature being 50-80° C.;
The non-adsorbed intermediate gas flowing out from the top of the second-stage PSA adsorption tower is mixed with the feed gas and returned to the first-stage PSA adsorption tower;
The desorbed gas flowing out from the bottom of the adsorption column of the second stage PSA is a concentrated gas.
a mid-temperature pressure swing adsorption process;
(2) A membrane separation process for membrane separating the pure HF liquid obtained in the intermediate temperature pressure swing adsorption process,
The pure HF liquid, which is pressurized to 1.0-1.6 MPa and has a temperature of 50-80° C., is passed through an inorganic ceramic membrane or a stainless steel membrane separation system, the membrane pore size of which is less than 1 micrometer, to obtain a purified pure HF liquid, in which the content of impurity SS particles having a diameter of more than 1 μm is less than 25 units/milliliter (Ea/ml);
The SS particle concentrate that has not passed through the membrane separation system is concentrated, cooled , and precipitated , the SS particles are removed, the liquid is heated and pressurized , and then returned to the membrane separation system, and a useful fraction of the liquid from which the SS particles have been removed is recovered .
A membrane separation process;
(3) a HF rectification step for rectifying the purified pure HF liquid obtained from the membrane separation step,
The purified pure HF liquid is introduced into a rectification column having a two-stage rectification column configuration,
The purified pure HF liquid is introduced into the top of the lower rectification column or into the bottom of the upper rectification column , and the light end impurity gas removed from the top of the upper rectification column is sent to a subsequent exhaust gas absorption step;
the non-condensable gas obtained after condensation of the distillate at the bottom of the upper rectification column or at the top of the lower rectification column is AHF gas having a purity of more than 99.99%;
The liquid obtained after condensation is recycled to the upper rectification column or the lower rectification column,
The non-condensable gas obtained after condensing the bottoms of the impurity fraction including the heavy fraction distilled from the bottom of the lower rectification column is returned to the medium temperature pressure swing adsorption step;
an HF rectification step;
(4) An ammonia water decarbonization process for treating the concentrated gas obtained from the intermediate temperature pressure swing adsorption process,
The concentrated gas is pressurized to normal pressure or a slight overpressure, and then ammonia water, sulfuric acid , and the distillate rectified from the lower rectification column of the HF rectification step are mixed and condensed based on the ratio, and the liquid obtained by the mixing and condensation is introduced into an ammonia water decarbonization absorption column as an absorbent;
A mixed solution of ammonium hydrogen carbonate and ammonium hydrogen fluoride is obtained from the bottom of the ammonia water decarbonization and absorption tower , and the mixed solution is used as raw material in the AHF production process by fluorosilicic acid method.
A method for purifying industrial-grade high-concentration HF into electronic-grade FTrPSA , comprising: The raw material gas described in the intermediate temperature pressure swing adsorption step (1) is industrial-level high-concentration hydrogen fluoride (HF ) gas produced in a process for producing anhydrous hydrogen fluoride (AHF) prepared by a fluorite process or a fluorosilicic acid process;
The industrial-level high-concentration hydrogen fluoride gas contains 95-99 % (v/v) HF , sulfuric acid _{( H2SO4} ), water ( _H2O ), sulfur dioxide ( _SO2 ), silicon tetrafluoride ( _SiF4 ), ammonia ( _NH3 ), _{fluorosilicic} acid ( _H2SiF6 ), carbon dioxide ( _CO2 ), chloride (calculated as HCl), as well as metal ions (Me+), fine particles (SS), and other impurity fractions ;
The metal ions are mainly water-soluble sodium (Na), magnesium (Mg), calcium (Ca), and arsenic (As) ions.
The diameter of the microparticles is greater than 1 micrometer (μm);
The method for purifying industrial-level high-concentration HF into electronic-level FTrPSA according to claim 1, characterized in that the temperature is 20-60° C., and the pressure is normal pressure or slight pressure. The membrane separation system in the membrane separation step (2) has a microfilter membrane or an ultrafiltration membrane as a membrane module.
2. The method for purifying industrial-level high-concentration HF into electronic-level FTrPSA according to claim 1. The light fraction impurity gas distilled from the top of the upper rectification tower in the HF rectification step is mixed with the non-condensable gas from the top of the ammonia water decarbonization absorption tower, and is introduced into an exhaust gas absorption tower using sulfuric acid as an absorbent, and a fluorosilicic acid solution is obtained from the bottom of the exhaust gas absorption tower;
The fluorosilicic acid solution is recycled and reused as a raw material in the process of producing nonaqueous hydrogen fluoride (AHF) by the fluorosilicic acid method,
The method for purifying industrial-level high-concentration HF into electronic-level FTrPSA according to claim 1, further comprising an exhaust gas absorption step in which the non-condensable gas flowing out from the top of the exhaust gas absorption tower is directly discharged as exhaust gas. The adsorption tower in the mid-temperature pressure swing adsorption step is loaded with activated aluminum oxide, silica gel , and molecular sieves;
the weight ratio of aluminum oxide:silica gel:molecular sieve in the adsorbent composition loaded in the adsorption column of the first stage PSA is (4-6):(2-4):(1-3);
The method for purifying industrial-level high-concentration HF into electronic-level FTrPSA according to claim 1, characterized in that the weight ratio of aluminum oxide:silica gel: molecular sieve in the adsorbent composition loaded in the adsorption tower of the second stage PSA is (3-5):(1-3):(3-5). The AHF gas obtained from the HF rectification step is further condensed to obtain AHF liquid;
The AHF liquid is put into a fluorine exchange resin to further remove metal ions , and an AHF liquid of UPSS electronic level is obtained ;
The UPSS electronic level AHF liquid is optionally mixed with deionized water to obtain an HF solution.
2. The method for purifying industrial-level high-concentration HF into electronic-level FTrPSA according to claim 1.

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