CN115535971B - Method for preparing high-purity electronic grade sulfuric acid from waste sulfuric acid solution - Google Patents
Method for preparing high-purity electronic grade sulfuric acid from waste sulfuric acid solution Download PDFInfo
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- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 title claims abstract description 466
- 239000002699 waste material Substances 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 42
- AKEJUJNQAAGONA-UHFFFAOYSA-N sulfur trioxide Chemical compound O=S(=O)=O AKEJUJNQAAGONA-UHFFFAOYSA-N 0.000 claims abstract description 126
- 239000000945 filler Substances 0.000 claims abstract description 22
- 239000000463 material Substances 0.000 claims abstract description 12
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims abstract description 11
- 239000004810 polytetrafluoroethylene Substances 0.000 claims abstract description 11
- 229910021645 metal ion Inorganic materials 0.000 claims abstract description 9
- 239000003595 mist Substances 0.000 claims abstract description 7
- 239000002253 acid Substances 0.000 claims abstract description 5
- 239000007789 gas Substances 0.000 claims description 92
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 claims description 86
- HIFJUMGIHIZEPX-UHFFFAOYSA-N sulfuric acid;sulfur trioxide Chemical compound O=S(=O)=O.OS(O)(=O)=O HIFJUMGIHIZEPX-UHFFFAOYSA-N 0.000 claims description 48
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 25
- 238000006243 chemical reaction Methods 0.000 claims description 16
- -1 polytetrafluoroethylene Polymers 0.000 claims description 13
- 238000001704 evaporation Methods 0.000 claims description 11
- 238000001816 cooling Methods 0.000 claims description 10
- 238000005336 cracking Methods 0.000 claims description 10
- 230000001590 oxidative effect Effects 0.000 claims description 10
- 229920001774 Perfluoroether Polymers 0.000 claims description 9
- 229920001577 copolymer Polymers 0.000 claims description 9
- 239000003054 catalyst Substances 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 230000008020 evaporation Effects 0.000 claims description 7
- 239000007800 oxidant agent Substances 0.000 claims description 7
- GNTDGMZSJNCJKK-UHFFFAOYSA-N divanadium pentaoxide Chemical group O=[V](=O)O[V](=O)=O GNTDGMZSJNCJKK-UHFFFAOYSA-N 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 4
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 claims description 3
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 3
- 239000000428 dust Substances 0.000 claims description 3
- 239000011148 porous material Substances 0.000 claims description 3
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 claims description 3
- 229910021642 ultra pure water Inorganic materials 0.000 claims description 3
- 239000012498 ultrapure water Substances 0.000 claims description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims 1
- 229910001882 dioxygen Inorganic materials 0.000 claims 1
- 239000004065 semiconductor Substances 0.000 abstract description 11
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 239000000243 solution Substances 0.000 description 69
- 238000004458 analytical method Methods 0.000 description 16
- 238000002835 absorbance Methods 0.000 description 9
- 239000003153 chemical reaction reagent Substances 0.000 description 9
- 239000007788 liquid Substances 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 229910052799 carbon Inorganic materials 0.000 description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 6
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 6
- 238000010521 absorption reaction Methods 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 229910052717 sulfur Inorganic materials 0.000 description 5
- 239000011593 sulfur Substances 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 4
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 4
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 4
- 238000000746 purification Methods 0.000 description 4
- 238000000197 pyrolysis Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 3
- 238000012856 packing Methods 0.000 description 3
- 229940085991 phosphate ion Drugs 0.000 description 3
- 239000006096 absorbing agent Substances 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000004737 colorimetric analysis Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 239000011552 falling film Substances 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 238000001095 inductively coupled plasma mass spectrometry Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 238000001745 non-dispersive infrared spectroscopy Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229920002120 photoresistant polymer Polymers 0.000 description 1
- 239000012286 potassium permanganate Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/69—Sulfur trioxide; Sulfuric acid
- C01B17/90—Separation; Purification
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/48—Sulfur dioxide; Sulfurous acid
- C01B17/50—Preparation of sulfur dioxide
- C01B17/58—Recovery of sulfur dioxide from acid tar or the like or from any waste sulfuric acid
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
A method for preparing high-purity electronic grade sulfuric acid from waste sulfuric acid solution comprises sequentially performing steps S1 to S7, wherein in particular, step S5 is to remove acid mist containing metal ions carried by sulfur trioxide gas with first purity in demisting equipment comprising at least two demisters connected in series, so as to obtain sulfur trioxide gas with second purity, each demister comprises a filler unit provided with a bearing frame and a filler filled in the bearing frame, the bearing frame is made of at least one material selected from PFA and M-PTFE, the filler is made of PFA or M-PTFE, the waste sulfuric acid solution can be regenerated to prepare high-purity electronic grade sulfuric acid, and the prepared high-purity electronic grade sulfuric acid is particularly suitable for semiconductor manufacturing processes.
Description
Technical Field
The invention relates to a method for recycling waste sulfuric acid solution, in particular to a method for preparing high-purity electronic grade sulfuric acid from waste sulfuric acid solution.
Background
In the current semiconductor industry, to remove organic matters such as chemicals and photoresist remained on the surface of silicon chips in the front-end process, a large amount of mixed solution containing electronic grade sulfuric acid and hydrogen peroxide is used for cleaning, and a large amount of waste sulfuric acid solution is generated. These waste sulfuric acid solutions, if not properly treated, are directly discharged, causing pollution and harm to the environment. In addition, with the rapid development of the semiconductor industry, the amount of electronic grade sulfuric acid used has increased, which means that a large amount of waste sulfuric acid solution is generated. Therefore, how to treat the waste sulfuric acid solution effectively is an important issue to be solved at present.
Disclosure of Invention
The invention aims to provide a method for preparing high-purity electronic grade sulfuric acid from waste sulfuric acid solution by recycling the waste sulfuric acid solution.
The invention relates to a method for preparing high-purity electronic grade sulfuric acid by using waste sulfuric acid solution, which comprises the following steps:
step S1: concentrating, cracking and purifying the waste sulfuric acid solution to obtain pure sulfur dioxide gas;
step S2: oxidizing the pure sulfur dioxide gas to sulfur trioxide gas in the presence of a catalyst to obtain a gas product containing sulfur trioxide gas;
step S3: absorbing the sulfur trioxide gas in the gas product and the residual pure sulfur dioxide gas with fuming sulfuric acid with a first concentration to obtain fuming sulfuric acid with a second concentration, oxidizing the residual sulfur dioxide in the fuming sulfuric acid with the second concentration into sulfur trioxide with an oxidant to form fuming sulfuric acid with a third concentration, wherein the relationship among the fuming sulfuric acid with the first concentration, the fuming sulfuric acid with the second concentration and the sulfur trioxide in the fuming sulfuric acid with the third concentration is that the fuming sulfuric acid with the second concentration and the fuming sulfuric acid with the third concentration are larger than the fuming sulfuric acid with the first concentration;
step S4: evaporating the fuming sulfuric acid with the third concentration at an evaporation temperature of 130-150 ℃ to extract sulfur trioxide gas from the fuming sulfuric acid with the third concentration to obtain sulfur trioxide gas with the first purity;
step S5: removing acid mist containing metal ions carried by the sulfur trioxide gas with the first purity in a demisting device to obtain sulfur trioxide gas with the second purity, wherein the purity of the sulfur trioxide in the sulfur trioxide gas with the second purity is higher than that of the sulfur trioxide in the sulfur trioxide gas with the first purity, the demisting device comprises at least two demisters connected in series, each demister comprises a filler unit, the filler unit is provided with a bearing frame and a filler carried on the bearing frame, the bearing frame is made of at least one material selected from tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer and modified polytetrafluoroethylene, and the filler is made of at least one material selected from tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer or modified polytetrafluoroethylene;
step S6: absorbing the sulfur trioxide gas having the second purity with an electronic grade sulfuric acid having the first purity to obtain an electronic grade sulfuric acid having the second purity, and the sulfuric acid concentration in the electronic grade sulfuric acid having the second purity is greater than the sulfuric acid concentration in the electronic grade sulfuric acid having the first purity; and
Step S7: and removing residual sulfur dioxide in the electronic grade sulfuric acid with the second purity to obtain electronic grade sulfuric acid with the third purity, wherein the sulfuric acid concentration in the electronic grade sulfuric acid with the third purity is larger than that in the electronic grade sulfuric acid with the second purity.
In the method for preparing high-purity electronic grade sulfuric acid from a spent sulfuric acid solution according to the present invention, in the step S5, the filler has a wire mesh shape or a 3D honeycomb shape, and the specific surface area of the filler ranges from 200m 2 /m 3 To 2000m 2 /m 3 。
In the method for preparing high-purity electronic grade sulfuric acid from a spent sulfuric acid solution according to the present invention, in the step S1, the concentration treatment includes concentrating the spent sulfuric acid solution in a vacuum environment to obtain a concentrated spent sulfuric acid solution having a sulfuric acid concentration greater than that of the spent sulfuric acid solution.
In the method for preparing high-purity electronic grade sulfuric acid by using the waste sulfuric acid solution, in the step S1, the cracking treatment comprises the steps of atomizing the concentrated waste sulfuric acid solution to form fog drops, and then carrying out cracking reaction at the temperature of 1000-1200 ℃ for 1.5-3.5 seconds to obtain the mixed gas containing sulfur dioxide gas, oxygen and water vapor.
In the method for preparing high-purity electronic grade sulfuric acid from waste sulfuric acid solution, in the step S1, the purification treatment comprises the steps of cooling the mixed gas from 1000 ℃ to 1200 ℃ to 300 ℃ to 400 ℃, and purifying the mixed gas and cooling the mixed gas to below 40 ℃ to obtain pure sulfur dioxide gas.
In the method for preparing high-purity electronic grade sulfuric acid from a spent sulfuric acid solution according to the present invention, in the step S2, the catalyst is selected from vanadium pentoxide.
In the method for preparing high-purity electronic grade sulfuric acid from a spent sulfuric acid solution according to the present invention, in the step S3, the oxidizing agent is at least one selected from hydrogen peroxide, sodium persulfate, and ozone.
In the method for preparing high-purity electronic grade sulfuric acid by using waste sulfuric acid solution, in the step S7, after the concentration of the electronic grade sulfuric acid with the second purity is adjusted by using ultrapure water, cooling is firstly carried out, and then compressed dry air without oil and dust is utilized to remove sulfur dioxide, so that the electronic grade sulfuric acid with the third purity is obtained.
In the method for preparing high-purity electronic grade sulfuric acid from a waste sulfuric acid solution according to the present invention, in the step S7, the residual sulfur dioxide in the electronic grade sulfuric acid having the second purity is oxidized with electronic grade hydrogen peroxide and then filtered, thereby obtaining the electronic grade sulfuric acid having the third purity.
In the method for preparing high-purity electronic grade sulfuric acid from a spent sulfuric acid solution according to the present invention, in the step S7, the filtration is performed in a filter comprising at least three filter cartridges, the filter cartridges being connected in series with each other, and the pore diameter of each filter cartridge being in the range of 0.003 μm to 0.1 μm, and the material of each filter cartridge comprising at least one of tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer and modified polytetrafluoroethylene.
The beneficial effects of the invention are that: by the mutual cooperation of the steps S1 to S7, particularly the demister used in the step S5 comprises at least two demisters connected in series, each demister is filled with the filler of a specific material, and then the waste sulfuric acid solution can be effectively regenerated to prepare high-purity electronic grade sulfuric acid, and the high-purity electronic grade sulfuric acid is particularly suitable for the semiconductor process.
Detailed Description
The invention relates to a method for preparing high-purity electronic grade sulfuric acid by using a waste sulfuric acid solution, which is a method for regenerating the waste sulfuric acid solution generated in the semiconductor manufacturing process to prepare the high-purity electronic grade sulfuric acid.
The term "spent sulfuric acid solution" as used herein generally refers to a sulfuric acid-containing waste liquid produced in a semiconductor process. The spent sulfuric acid solution may contain chemicals used in semiconductor processing, such as, but not limited to, hydrogen peroxide, and residues thereof, in addition to sulfuric acid and water. The sulfuric acid concentration in the spent sulfuric acid solution is not particularly limited, and for example, the sulfuric acid concentration in the spent sulfuric acid solution is 40wt% to 75wt% in terms of the spent sulfuric acid solution produced in a general semiconductor process.
The first embodiment of the method for preparing high-purity electronic grade sulfuric acid from waste sulfuric acid solution comprises the following steps:
step S1: and (3) concentrating, cracking and purifying the waste sulfuric acid solution in sequence to obtain pure sulfur dioxide gas.
The concentration treatment comprises concentrating the waste sulfuric acid solution in a vacuum environment to obtain a concentrated waste sulfuric acid solution with sulfuric acid concentration greater than that of the waste sulfuric acid solution. For example, the concentration of sulfuric acid in the concentrated spent sulfuric acid solution obtained by performing the concentration may be up to 80 to 90wt% in terms of the concentration of sulfuric acid in the spent sulfuric acid solution being 40 to 75wt%. The way of concentrating the spent sulfuric acid solution is not particularly limited, for example, but not limited to, evaporating the spent sulfuric acid solution by heating in a vacuum environment using a vacuum evaporation apparatus to concentrate. The hydrogen peroxide vapor and water vapor generated during the concentration are introduced into a condensing device and condensed to form an aqueous hydrogen peroxide solution.
The cracking treatment comprises that the concentrated waste sulfuric acid solution is atomized to form fog drops, and then cracking reaction is carried out for 1.5 seconds to 3.5 seconds at the temperature of 1000 ℃ to 1200 ℃ to obtain mixed gas containing sulfur dioxide gas, oxygen and water vapor. The manner of atomizing the concentrated spent sulfuric acid solution to form mist droplets is not particularly limited, and for example, but not limited to, atomizing the concentrated spent sulfuric acid solution to form mist droplets with air having a pressure in the range of 0.3MPa to 0.6MPa using a two-fluid atomizing spray gun. The manner of carrying out the pyrolysis reaction is not particularly limited, for example, but not limited to, passing the droplets into a pyrolysis furnace and passing natural gas or sulfur mixed with air into the pyrolysis furnace to produce the thermal energy required for the pyrolysis reaction of the droplets.
The purification treatment comprises the steps of cooling the mixed gas from 1000 ℃ to 1200 ℃ to 300 ℃ to 400 ℃, and then purifying the mixed gas and cooling the mixed gas to below 40 ℃ to obtain pure sulfur dioxide gas. The way of cooling the mixed gas from 1000 ℃ to 1200 ℃ to 300 ℃ to 400 ℃ is not particularly limited, for example but not limited to, using a waste heat boiler to recover the high temperature heat of the mixed gas to generate steam to cool the mixed gas. The way of purifying and cooling the mixed gas to below 40 ℃ is not particularly limited, for example, but not limited to, introducing the mixed gas cooled to 300 ℃ to 400 ℃ into a reverse spray scrubber to further cool the mixed gas and remove uncleaved concentrated spent sulfuric acid solution, uncleaved sulfur trioxide gas, refractory sludge from the cracking furnace and the like in the mixed gas, thereby obtaining pure sulfur dioxide gas.
Step S2: oxidizing the pure sulfur dioxide gas to sulfur trioxide gas in the presence of a catalyst to obtain a gas product comprising sulfur trioxide gas. In some embodiments of the present invention, the pure sulfur dioxide gas is passed into a catalytic reaction tower filled with the catalyst, and air is passed into the catalytic reaction tower to oxidize the pure sulfur dioxide gas to sulfur trioxide gas. The catalyst species may be a catalyst commonly used to convert sulfur dioxide to sulfur trioxide, such as, but not limited to, vanadium pentoxide, and the like.
Step S3: absorbing the sulfur trioxide gas in the gas product and the residual pure sulfur dioxide gas with fuming sulfuric acid with a first concentration to obtain fuming sulfuric acid with a second concentration, oxidizing the residual sulfur dioxide in the fuming sulfuric acid with the second concentration into sulfur trioxide with an oxidant to form fuming sulfuric acid with a third concentration, wherein the relationship among the fuming sulfuric acid with the first concentration, the fuming sulfuric acid with the second concentration and the sulfur trioxide concentration in the fuming sulfuric acid with the third concentration is that the fuming sulfuric acid with the second concentration and the fuming sulfuric acid with the third concentration are larger than the fuming sulfuric acid with the first concentration. In some embodiments of the present invention, the step S3 is performed in an absorber filled with the oleum having the first concentration and added with an oxidizing agent such as, but not limited to, hydrogen peroxide, sodium persulfate, ozone, etc., which is sufficient to oxidize the sulfur dioxide remaining in the oleum having the second concentration to sulfur trioxide, and the oxidizing agent may be used singly or in combination. In addition, the exhaust gas generated during the absorption of the gaseous product by the oleum having the first concentration is passed through an exhaust gas absorption tower to recover sulfur trioxide gas in the exhaust gas. The terms "fuming sulfuric acid having a first concentration", "fuming sulfuric acid having a second concentration" and "fuming sulfuric acid having a third concentration" are intended to indicate the level of the concentration of sulfur trioxide in fuming sulfuric acid, the concentration of sulfur trioxide in fuming sulfuric acid having a first concentration, fuming sulfuric acid having a second concentration and fuming sulfuric acid having a third concentration is not particularly limited, for example, but not limited to, the concentration range of sulfur trioxide in fuming sulfuric acid having a second concentration is 25wt% to 40wt% and the concentration range of sulfur dioxide is 5ppm to 50ppm, and the concentration range of sulfur trioxide in fuming sulfuric acid having a third concentration is 25wt% to 40wt% and the concentration range of sulfur dioxide is 0ppm to 0.5ppm.
Step S4: and evaporating the fuming sulfuric acid with the third concentration at an evaporation temperature of 130-150 ℃ to extract sulfur trioxide gas from the fuming sulfuric acid with the third concentration, so as to obtain sulfur trioxide gas with the first purity. The evaporation treatment is performed by, for example, but not limited to, introducing the fuming sulfuric acid with the third concentration into an evaporator, such as, but not limited to, a rising film evaporator or a falling film evaporator, via a preheater. Further, the fuming sulfuric acid having the third concentration remaining after the evaporation treatment may be returned to the absorption column via the preheater as needed.
It is worth mentioning that by controlling the evaporation temperature of the evaporation treatment to 130 ℃ to 150 ℃, the occurrence of metal elution caused by corrosion of the evaporator by acid can be avoided.
Step S5: removing acid mist containing metal ions entrained in the sulfur trioxide gas with the first purity in a demisting device to obtain sulfur trioxide gas with the second purity, wherein the purity of sulfur trioxide in the sulfur trioxide gas with the second purity is higher than that of sulfur trioxide in the sulfur trioxide gas with the first purity.
The demister apparatus comprises at least two demisters connected in series with each other, and each demister comprises a packing unit. The packing unit is provided with a bearing frame and packing filled in the bearing frame. The material of the bearing frame is at least one selected from tetrafluoroethylene-perfluoro alkoxy vinyl ether copolymer (PFA) and modified polytetrafluoroethylene (M-PTFE). The filler is made of tetrafluoroethylene-perfluoro alkoxy vinyl ether copolymer or modified polytetrafluoroethylene. The filler material of the filler units in each demister can be the same or different. Preferably, the filler has a wire mesh shape or a 3D honeycomb shape, and the specific surface area of the filler is in the range of 200m 2 /m 3 To 2000m 2 /m 3 。
Step S6: absorbing the sulfur trioxide gas having the second purity with the electronic grade sulfuric acid having the first purity to obtain the electronic grade sulfuric acid having the second purity, and the sulfuric acid concentration in the electronic grade sulfuric acid having the second purity is greater than the sulfuric acid concentration in the electronic grade sulfuric acid having the first purity. In some embodiments of the invention, the step S6 is performed in an absorber filled with the electronic grade sulfuric acid having the first purity.
Step S7: and removing residual sulfur dioxide in the electronic grade sulfuric acid with the second purity to obtain electronic grade sulfuric acid with the third purity, wherein the sulfuric acid concentration in the electronic grade sulfuric acid with the third purity is larger than that in the electronic grade sulfuric acid with the second purity. In step S7 of the first embodiment, after the concentration of the electronic grade sulfuric acid with the second purity is adjusted by ultrapure water, the electronic grade sulfuric acid with the third purity is obtained by cooling and then removing residual sulfur dioxide by using Compressed Dry Air (CDA) without oil and dust.
The second embodiment of the method for preparing high-purity electronic grade sulfuric acid from a waste sulfuric acid solution according to the present invention is different from the first embodiment in that in step S7 of the second embodiment, the electronic grade sulfuric acid having the third purity is obtained by oxidizing residual sulfur dioxide in the electronic grade sulfuric acid having the second purity with electronic grade hydrogen peroxide and then filtering. Wherein the filtration is performed in a filter comprising at least three filter elements connected in series. The pore diameter of each filter element ranges from 0.003 mu M to 0.1 mu M, and the material of each filter element comprises at least one of tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (PFA) and modified polytetrafluoroethylene (M-PTFE).
The invention will be further illustrated with respect to the following specific examples, but it should be understood that the examples are for illustrative purposes only and are not to be construed as limiting the practice of the invention.
Examples 1 to 3
Examples 1 to 3 are the steps of treating the waste sulfuric acid solution according to the first example described above to prepare electronic grade sulfuric acid having a third purity. The process parameters conditions for examples 1-3 are shown in Table 1 below.
[ evaluation of Properties ]
The test patterns of each property evaluation item will be described below by way of example 1, and the other examples were analyzed according to the same test patterns, and the results of property evaluation are shown in tables 1 and 2.
Analysis of sulfuric acid content and hydrogen peroxide content in the spent sulfuric acid solution and concentrated spent sulfuric acid solution: and measuring the waste sulfuric acid solution and the concentrated waste sulfuric acid solution by an automatic titrator to obtain the sulfuric acid content and the hydrogen peroxide content in the waste sulfuric acid solution and the concentrated waste sulfuric acid solution.
Analysis of total organic carbon content in the spent sulfuric acid solution and concentrated spent sulfuric acid solution: and measuring the waste sulfuric acid solution and the concentrated waste sulfuric acid solution by using a total organic carbon analyzer to obtain the total organic carbon in the waste sulfuric acid solution and the concentrated waste sulfuric acid solution.
Analysis of the water content in the spent sulfuric acid solution and the concentrated spent sulfuric acid solution: and subtracting the measured sulfuric acid content, hydrogen peroxide content and total organic carbon content in the waste sulfuric acid solution from the total amount of the waste sulfuric acid solution which is 100wt%, so as to obtain the water content in the waste sulfuric acid solution. The water content of the concentrated spent sulfuric acid solution is obtained in the same manner and will not be described in detail herein.
Oxygen content in the mixed gas of the sulfur dioxide-containing gas: the oxygen content of the mixed gas containing sulfur dioxide gas in example 1 was measured in-situ (in-situ) with an oxygen analyzer.
Sulfur recovery rate of the purification treatment of step S1: (sulfur content in spent sulfuric acid solution-sulfur content in wastewater produced by the purification treatment)/(sulfur content in spent sulfuric acid solution. Times.100%).
Sulfur dioxide conversion in step S2: (content of pure sulfur dioxide gas-content of sulfur dioxide gas in a gas product containing sulfur trioxide gas)/(content of pure sulfur dioxide gas X100%).
Sulfur trioxide absorption rate of step S3: (content of sulfur trioxide gas in the sulfur trioxide gas-content of sulfur trioxide in the exhaust gas)/(content of sulfur trioxide gas in the sulfur trioxide gas-containing gas)/(100%).
Purity: the purity of electronic grade sulfuric acid having the third purity of example 1 was measured by an automatic titrator according to the method of analyzing high purity sulfuric acid of JIS K9905 (1995 edition).
Colorimetric analysis of electronic grade sulfuric acid: the color of electronic grade sulfuric acid of example 1 having a third purity was measured using a cuvette having a standard color, with analytical guidelines for SEMI C1-0310 (2010 edition) liquid chemicals.
And (3) analyzing the content of burning residues: the burned residue content in the electronic grade sulfuric acid of example 1 having the third purity was measured by a method of analyzing high purity sulfuric acid in accordance with JIS K9905 (1995 edition) and using a high temperature furnace and a precision balance.
Analysis of the content of reducing substances: the reduced matter content in the electronic grade sulfuric acid having the third purity of example 1 was obtained by performing redox titration of the electronic grade sulfuric acid having the third purity of example 1 with potassium permanganate in accordance with the analytical method of JIS K9905 (1995 edition), and further taking the molecular weight of sulfur dioxide as the calculation basis of the reduced matter content in the electronic grade sulfuric acid having the third purity of example 1.
Analysis of ammonium ion content: according to the analysis method of JIS K9905 (1995 edition), a plurality of electronic grade sulfuric acid standards with known ammonium ion content are taken, after reaction reagents are utilized to react with ammonium ions in each electronic grade sulfuric acid standard, an ultraviolet-visible light spectroscope is used for measuring the absorbance of each reacted electronic grade sulfuric acid standard, and the absorbance of all the reacted electronic grade sulfuric acid standards and the ammonium ion content are manufactured into a measuring line, so that a linear equation is obtained. Then, the reaction reagent is added into the electronic grade sulfuric acid with the third purity of the embodiment 1, the reaction reagent reacts with ammonium ions in the electronic grade sulfuric acid with the third purity of the embodiment 1 to obtain a liquid to be tested, the ultraviolet-visible light spectroscope is used for measuring the absorbance of the liquid to be tested, and the ammonium ion content in the electronic grade sulfuric acid with the third purity of the embodiment 1 is calculated by the linear equation.
Analysis of chloride ion content: according to the analysis method of JIS K9905 (1995 edition), a plurality of electronic grade sulfuric acid standards containing known chloride ion content are taken, after reaction reagents are utilized to react with chloride ions in each electronic grade sulfuric acid standard, turbidity of each reacted electronic grade sulfuric acid standard is measured by a turbidity meter, and turbidity and chloride ion content of all the reacted electronic grade sulfuric acid standards are manufactured into a measuring line, so that a linear equation is obtained. Then, the reaction reagent is added into the electronic grade sulfuric acid with the third purity in the embodiment 1, so that the reaction reagent reacts with chloride ions in the electronic grade sulfuric acid with the third purity in the embodiment 1 to obtain a liquid to be tested, the turbidity of the liquid to be tested is measured by the turbidity meter, and the chloride ion content in the electronic grade sulfuric acid with the third purity in the embodiment 1 is calculated by the linear equation.
Nitrate ion content analysis: according to the analysis method of JIS K9905 (1995 edition), a plurality of electronic grade sulfuric acid standards containing known nitrate ion content are taken, the absorbance of each electronic grade sulfuric acid standard is measured by an ultraviolet-visible light spectroscope, and the absorbance and the nitrate ion content of all electronic grade sulfuric acid standards are manufactured into a measuring line, so that a linear equation is obtained. Then, absorbance of the electronic grade sulfuric acid having the third purity of example 1 was measured using the ultraviolet-visible light spectroscope, and nitrate ion content in the electronic grade sulfuric acid having the third purity of example 1 was calculated by the linear equation.
Phosphate ion content analysis: according to the analysis method of JIS K9905 (1995 edition), a plurality of electronic grade sulfuric acid standards containing known phosphate ion content are taken, after reaction reagents are utilized to react with phosphate ions in each electronic grade sulfuric acid standard, an ultraviolet-visible light spectroscope is used for measuring the absorbance of each reacted electronic grade sulfuric acid standard, and the absorbance of all the reacted electronic grade sulfuric acid standards and the phosphate ion content are manufactured into a measuring line, so that a linear equation is obtained. Then, the reaction reagent is added into the electronic grade sulfuric acid with the third purity in the embodiment 1, the reaction reagent reacts with phosphate ions in the electronic grade sulfuric acid with the third purity in the embodiment 1 to obtain a liquid to be tested, the absorbance of the liquid to be tested is measured by using the ultraviolet-visible light spectroscope, and the content of the phosphate ions in the electronic grade sulfuric acid with the third purity in the embodiment 1 is obtained through the calculation of the linear equation.
Analysis of total organic carbon: the total organic carbon content in the electronic grade sulfuric acid of example 1 having the third purity was measured by non-dispersive infrared (non-dispersive infrared, NDIR) under the condition of high temperature catalytic oxidation using a total organic carbon analyzer.
Analysis of metal ion content: the metal ion content of the electronic grade sulfuric acid of example 1 having a third purity was analyzed using an inductively coupled plasma mass spectrometer (manufacturer: agilent; model: ICP-MS 8900).
TABLE 1
Referring to table 1, the methods of examples 1 to 3 for preparing high purity electronic grade sulfuric acid from spent sulfuric acid solution have a sulfur dioxide conversion rate of 99.85% or more and a sulfur trioxide absorption rate of 99.95% or more, illustrating that the methods of examples 1 to 3 can effectively convert sulfur dioxide into sulfur trioxide, and the sulfur trioxide can be effectively absorbed by fuming sulfuric acid having a first concentration to thereby prepare electronic grade sulfuric acid having a third purity in the subsequent steps S4 to S7, and the concentration of the electronic grade sulfuric acid having the third purity is as high as 96% or more.
TABLE 2
Referring to table 2, from the results of the metal ion content analysis of examples 1 to 3, it is understood that each of the electronic grade sulfuric acid having the third purity of examples 1 to 3 has a content of less than 5ppt. It should be noted that, according to the current industry classification standards for the purity of electronic grade sulfuric acid, when the content of metal ions in electronic grade sulfuric acid is less than 10ppt, the electronic grade sulfuric acid is classified into the electronic grade sulfuric acid with the highest purity, and the electronic grade sulfuric acid with the highest purity is particularly suitable for the semiconductor process with the line width of less than 10 nanometers, so that the content of metal ions in electronic grade sulfuric acid with the third purity in examples 1 to 3 accords with the current industry classification standards for electronic grade sulfuric acid with the highest purity.
In summary, the method for preparing high-purity electronic grade sulfuric acid from waste sulfuric acid solution according to the present invention is particularly suitable for use in semiconductor manufacturing processes by mutually cooperating steps S1 to S7, particularly, the demister used in step S5 comprises at least two demisters connected in series, each demister is filled with the filler of a specific material, and then the waste sulfuric acid solution can be effectively regenerated to prepare high-purity electronic grade sulfuric acid, which is particularly suitable for use in semiconductor manufacturing processes, so that the purpose of the present invention can be truly achieved.
However, the foregoing is only illustrative of the present invention and is not to be construed as limiting the scope of the invention, which is defined by the appended claims and their equivalents.
Claims (10)
1. A method for preparing high-purity electronic grade sulfuric acid from waste sulfuric acid solution, which is characterized by comprising the following steps:
step S1: concentrating, cracking and purifying the waste sulfuric acid solution to obtain pure sulfur dioxide gas;
step S2: oxidizing the pure sulfur dioxide gas to sulfur trioxide gas in the presence of a catalyst to obtain a gas product containing sulfur trioxide gas;
step S3: absorbing the sulfur trioxide gas in the gas product and the residual pure sulfur dioxide gas with fuming sulfuric acid with a first concentration to obtain fuming sulfuric acid with a second concentration, oxidizing the residual sulfur dioxide in the fuming sulfuric acid with the second concentration into sulfur trioxide with an oxidant to form fuming sulfuric acid with a third concentration, wherein the relationship among the fuming sulfuric acid with the first concentration, the fuming sulfuric acid with the second concentration and the sulfur trioxide in the fuming sulfuric acid with the third concentration is that the fuming sulfuric acid with the second concentration and the fuming sulfuric acid with the third concentration are larger than the fuming sulfuric acid with the first concentration;
step S4: evaporating the fuming sulfuric acid with the third concentration at an evaporation temperature of 130-150 ℃ to extract sulfur trioxide gas from the fuming sulfuric acid with the third concentration to obtain sulfur trioxide gas with the first purity;
step S5: removing acid mist containing metal ions carried by the sulfur trioxide gas with the first purity in a demisting device to obtain sulfur trioxide gas with the second purity, wherein the purity of the sulfur trioxide in the sulfur trioxide gas with the second purity is higher than that of the sulfur trioxide in the sulfur trioxide gas with the first purity, the demisting device comprises at least two demisters connected in series, each demister comprises a filler unit, the filler unit is provided with a bearing frame and a filler filled in the bearing frame, the bearing frame is made of at least one material selected from tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer and modified polytetrafluoroethylene, and the filler is made of at least one material selected from tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer or modified polytetrafluoroethylene;
step S6: absorbing the sulfur trioxide gas having the second purity with an electronic grade sulfuric acid having the first purity to obtain an electronic grade sulfuric acid having the second purity, and the sulfuric acid concentration in the electronic grade sulfuric acid having the second purity is greater than the sulfuric acid concentration in the electronic grade sulfuric acid having the first purity; and
Step S7: and removing residual sulfur dioxide in the electronic grade sulfuric acid with the second purity to obtain electronic grade sulfuric acid with the third purity, wherein the sulfuric acid concentration in the electronic grade sulfuric acid with the third purity is larger than that in the electronic grade sulfuric acid with the second purity.
2. The method for preparing high-purity electronic grade sulfuric acid from a spent sulfuric acid solution according to claim 1, characterized in that: in the step S5, the filler is in the shape of a silk net or a 3D honeycomb, and the specific surface area of the filler is in the range of 200m 2 /m 3 To 2000m 2 /m 3 。
3. The method for preparing high-purity electronic grade sulfuric acid from a spent sulfuric acid solution according to claim 1, characterized in that: in the step S1, the concentration process includes concentrating the waste sulfuric acid solution in a vacuum environment to obtain a concentrated waste sulfuric acid solution having a sulfuric acid concentration greater than that of the waste sulfuric acid solution.
4. A method for preparing high purity electronic grade sulfuric acid from spent sulfuric acid solution according to claim 3, characterized in that: in the step S1, the cracking treatment includes atomizing the concentrated waste sulfuric acid solution to form mist droplets, and then performing a cracking reaction at 1000 ℃ to 1200 ℃ for 1.5 seconds to 3.5 seconds to obtain a mixed gas containing sulfur dioxide gas, oxygen gas and water vapor.
5. The method for preparing high-purity electronic grade sulfuric acid from a spent sulfuric acid solution according to claim 4, characterized in that: in the step S1, the purifying treatment includes cooling the mixed gas from 1000 ℃ to 1200 ℃ to 300 ℃ to 400 ℃, and then purifying the mixed gas and cooling the mixed gas to below 40 ℃ to obtain pure sulfur dioxide gas.
6. The method for preparing high-purity electronic grade sulfuric acid from a spent sulfuric acid solution according to claim 1, characterized in that: in the step S2, the catalyst is selected from vanadium pentoxide.
7. The method for preparing high-purity electronic grade sulfuric acid from a spent sulfuric acid solution according to claim 1, characterized in that: in the step S3, the oxidizing agent is at least one selected from hydrogen peroxide, sodium persulfate, and ozone.
8. The method for preparing high-purity electronic grade sulfuric acid from a spent sulfuric acid solution according to claim 1, characterized in that: in the step S7, after the concentration of the second purity electronic grade sulfuric acid is adjusted by ultrapure water, the electronic grade sulfuric acid is cooled and cooled, and then the compressed dry air without oil and dust is used for removing sulfur dioxide, so that the third purity electronic grade sulfuric acid is obtained.
9. The method for preparing high-purity electronic grade sulfuric acid from a spent sulfuric acid solution according to claim 1, characterized in that: in the step S7, the sulfur dioxide remaining in the electronic grade sulfuric acid with the second purity is oxidized with electronic grade hydrogen peroxide and then filtered, so as to obtain the electronic grade sulfuric acid with the third purity.
10. The method for preparing high-purity electronic grade sulfuric acid from a spent sulfuric acid solution according to claim 9, characterized in that: in the step S7, the filtering is performed in a filter comprising at least three filter elements connected in series, wherein the pore diameter of each filter element ranges from 0.003 μm to 0.1 μm, and the material of each filter element comprises at least one of tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer and modified polytetrafluoroethylene.
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