CN110357045B - Method for recycling organic silicon waste acid - Google Patents
Method for recycling organic silicon waste acid Download PDFInfo
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- CN110357045B CN110357045B CN201910439619.5A CN201910439619A CN110357045B CN 110357045 B CN110357045 B CN 110357045B CN 201910439619 A CN201910439619 A CN 201910439619A CN 110357045 B CN110357045 B CN 110357045B
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- 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
- C01B17/88—Concentration of sulfuric acid
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- 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
- C01B17/905—Removal of organic impurities
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
- Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
Abstract
The invention relates to the technical field of waste acid treatment, in particular to a method for recycling organic silicon waste acid; firstly, organic matters such as methyl chloride, methanol, dimethyl ether and the like are recovered through dilution and stripping treatment, and the waste acid is partially purified; then, the water is purified and concentrated again by a process combining sectional vacuum concentration and oxidation, so that the aim of thorough purification is fulfilled, the requirements of a clean production process are met, and the water-purifying method belongs to the green environmental protection technology; the method realizes the recycling of sulfuric acid and the recovery of organic matters in the production process of organic silicon, improves the industrial value of the organic silicon, reduces the industrial production cost of the organic silicon, and has obvious economic benefit; in addition, the method eliminates environmental pollution, is beneficial to improving the environmental quality and has good social benefit.
Description
Technical Field
The invention belongs to the technical field of waste acid treatment, and particularly relates to a method for recycling organic silicon waste acid, which has zero emission of the whole process and belongs to the green and environment-friendly technology.
Background
At present, the domestic and foreign methods for treating the waste acid liquid mainly comprise a waste acid cracking method, a waste acid concentration method, a solvent extraction method, an ion exchange method, a membrane separation method, a chemical conversion method and the like, and the methods have advantages and disadvantages in practical application, and a single process is difficult to meet the target requirement.
In the process of synthesizing methyl chlorosilane by a direct method, methanol and hydrogen chloride generate methyl chloride, and a side reaction of generating dimethyl ether by methanol dehydration also occurs, and crude methyl chloride obtained by the reaction can be used in a production system by purification treatment methods such as water washing, alkali washing, multistage drying of sulfuric acid and the like. The multistage drying of the sulfuric acid is realized by adopting 98% concentrated sulfuric acid, and after the concentrated sulfuric acid absorbs water, dimethyl ether, a small amount of methyl sulfate, dimethyl sulfate, methanol, siloxane and other substances, the concentration of the concentrated sulfuric acid is reduced to below 80% and can be polluted by the impurities, the purification and drying performance is reduced, and the concentrated sulfuric acid cannot be used continuously. Therefore, a large amount of waste acid liquid is generated, and if the waste acid liquid is not effectively treated, not only can serious environmental pollution be caused, but also great resource waste can be caused.
CN101287677AWO2007042476A1 discloses a method for regenerating sulfuric acid, characterized in that 1, sulfuric acid contaminated with a second component of O-methyl sulfuric acid, dimethyl ether, methanol, aliphatic hydrocarbon, olefin, chlorinated hydrocarbon or organosilicon compound is diluted to a concentration of not more than 55% sulfuric acid by adding liquid water and introducing water vapor, and heated to boiling at a temperature of not more than 135 ℃; 2. concentrating under reduced pressure at a temperature of at least 170 ℃ to a concentration of at least 80% and subsequently reacting with an oxidizing agent. The invention mainly provides a method for regenerating sulfuric acid, but the method does not relate to the problem of recycling other organic matters, and meanwhile, the sulfuric acid is oxidized at low temperature, so that on one hand, the low temperature is not favorable for oxidation, the organic matters cannot be completely oxidized, the residual organic matters can be carbonized due to continuous concentration, the consumption of an oxidant is increased, and on the other hand, the obtained finished acid also contains organic matters which can influence the reuse.
Patent WO2010/066017A1CA2646311A1 discloses a sulfuric acid purification process, the waste acid contains a small amount of methyl sulfuric acid, dimethyl ether, methanol, fats and olefins, chlorinated hydrocarbons and organic silicon compounds, and consists of an organic matter two-stage evaporation process. a) Diluting the waste acid by using steam and distilled water, wherein the lowest temperature of the diluted mixture cannot be lower than 100 ℃, so that the aim of hydrolyzing methyl sulfate into sulfuric acid and methanol is fulfilled, and methyl chloride and dimethyl ether are evaporated to obtain primary diluted sulfuric acid and primary organic matter steam containing methyl chloride and dimethyl ether; b) Removing the chloromethane and dimethyl ether vapor; c) Introducing the dilute acid and the water vapor into a stripping tower in a countercurrent mode to obtain secondary volatile organic matter vapor and secondary diluted sulfuric acid; d) Removing the second stage volatile organic vapor; and collecting the second stage diluted sulfuric acid. The carbonized organic matters in the steam stripping process are eliminated through the two-stage process, and solid particle pollutants are removed through the subsequent stage concentration process steps. The invention mainly provides a sulfuric acid purification process, but the energy consumption for recovering organic matters by adopting a steam stripping mode is larger, and the consumption of an oxidant is larger by adopting a two-stage oxidation process.
Patent CN109721035A discloses a process flow of adding medicament into waste sulfuric acid for decoloring, tail gas absorption, membrane filtration of impurities, blowing and deacidification of organic matters, and then performing negative pressure evaporation and concentration; the invention mainly provides a purification and concentration process of waste dilute sulfuric acid, which does not show whether the consumption of a decoloration oxidant and the quality of a finished product acid can meet the use requirement, and the finished product acid obtained by operating according to the method is black and has a high COD value, which shows that the method can not achieve the purpose of purifying the waste sulfuric acid; and the organic matters in the waste acid are not recycled, and the oxidized tail gas is only safely discharged after entering a tail gas treatment system for washing, so that the resource waste is caused.
Disclosure of Invention
The invention aims to provide a method for recycling organic silicon waste acid, which has zero emission of the whole process, belongs to the green and environment-friendly technology and overcomes the defects of the prior art.
The technical problem to be solved by the invention is realized by the following technical scheme:
respectively carrying out dilution and stripping treatment to recover organic matters such as chloromethane, methanol, dimethyl ether and the like, and partially purifying the waste acid; then the purification and concentration are carried out again by the combination of the vacuum concentration and the oxidation in stages, thereby achieving the purpose of thorough purification and meeting the requirements of the clean production process.
A method for recycling organic silicon waste acid comprises the following steps:
step 1, dilution: diluting the waste acid solution by any one or more of water, distilled water and steam, so as to decompose the molten salt formed by the dimethyl ether and the sulfuric acid and recover the molten salt into sulfuric acid and dimethyl ether;
step 2, stripping: carrying out air stripping treatment on the diluted sulfuric acid, and recovering organic matters such as chloromethane, methanol, dimethyl ether and the like to achieve the purpose of partial purification of the sulfuric acid;
step 3, concentration and oxidation: the waste acid after the stripping treatment is subjected to sectional concentration treatment under the vacuum condition, the oxidizing agent is added for oxidation treatment after the first-stage concentration, the aim of secondary purification is achieved, and the sulfuric acid is dispersed by mass to more than 96% through the second-stage concentration and can enter a production system for recycling;
preferably, in the step 1, the mass fraction of the diluted waste sulfuric acid is between 40% and 50%, preferably between 40% and 45%.
Preferably, in the step 2, the stripping is performed by using preheated air or nitrogen, and the temperature of the top of the stripping tower is not lower than 100 ℃.
Preferably, in the step 3, the vacuum condition of the first-stage concentration is that the absolute pressure is 6-12 kpa, the temperature is 170-190 ℃, and the mass fraction of the concentrated sulfuric acid is 88-90%.
Preferably, in the step 3, the oxidizing agent is any one of nitric acid or hydrogen peroxide.
Preferably, in the step 3, the temperature and absolute pressure of the oxidation are consistent with the operating conditions of the first stage of concentration.
Preferably, in the step 3, the oxidation retention time is 5-30 min;
preferably, in the step 3, the vacuum condition of the second-stage concentration is that the absolute pressure is 2-6 kpa, the temperature is 185-210 ℃, the mass fraction of the concentrated sulfuric acid is more than or equal to 96%, and the COD is less than or equal to 300mg/l.
Compared with the prior art, the invention has the advantages that:
1) The purified sulfuric acid can form a closed loop, the recycling of a production system can be met, fresh sulfuric acid is not needed any more, the production cost is reduced, resources are saved, and the environmental pollution is reduced;
2) The waste acid after being diluted is blown off by adopting nitrogen or air, so that the energy consumption can be effectively reduced;
3) The oxidation treatment is carried out at a higher temperature, so that the oxidation of the organic matters is more thorough, and the consumption of the oxidant can be reduced;
4) The concentration process adopts a horizontal bayonet tube heater and is carried out in a static self-flowing heating mode, so that the process is simplified, the energy consumption is reduced, and the reliability of the device is improved.
5) The mass fraction of the purified sulfuric acid is more than or equal to 96 percent, the COD is less than or equal to 300mg/l, the appearance is kept clear and transparent, and the process is mature, safe and reliable.
Drawings
FIG. 1 is a block diagram of the process flow of resource utilization of the present invention.
Detailed Description
The present invention will be described in detail with reference to examples.
The waste sulfuric acid used in the following examples had the following specific composition:
the mass fraction of sulfuric acid is about 75%, the mass fraction of water is about 5%, the mass fraction of dimethyl ether is about 10%, the mass fraction of methanol is about 3%, the mass fraction of methyl sulfate is about 2%, and methyl chloride and siloxane are both trace.
COD was determined according to the protocol in HJ 828-2017 to give: more than 300000mg/l
Example 1
Diluting the waste acid and water in a dilution tank according to a certain ratio, wherein the mass fraction of the diluted acid is 40%, and the diluted acid enters a stripping tower (filled with glass spring packing, the size of the stripping tower:
the size of the filler: diameter of
Length 10-20 mm). Blowing preheated air from the bottom, maintaining the temperature at the top of the stripping tower at 100 ℃, and introducing volatile organic matter steam at the top of the stripping tower into a condenser to recover organic matters such as methyl chloride, methanol, dimethyl ether and the like, thereby achieving the purpose of partial purification of sulfuric acid; after the tower kettle is purified for the first time, the waste acid enters a No. 1 concentration kettle, vacuum concentration is carried out under the conditions that the absolute pressure is 12kpa and the temperature is 190 ℃, and the mass fraction of concentrated sulfuric acid is 89.5%; and (3) adding the kettle liquid into an oxidation kettle, slowly dropwise adding 5g (mass fraction is 65%) of nitric acid, performing oxidation treatment under the condition that the temperature and the absolute pressure are kept unchanged, staying for 5min, then adding the nitric acid into a No. 2 concentration kettle, performing vacuum concentration under the conditions that the absolute pressure is 5kpa and the temperature is 210 ℃ to obtain a light yellow transparent clear finished product sulfuric acid, and detecting that the mass fraction of the sulfuric acid is 96.7% and the COD is 280mg/l.
Example 2
And (2) taking the waste acid and distilled water according to a certain proportion, diluting in a diluting tank, wherein the diluted acid fraction is 42%, and the diluted acid enters a stripping tower (filled with glass spring packing, the size of the stripping tower:
the size of the filler: diameter of
Length 10-20 mm). Blowing preheated nitrogen from the bottom, maintaining the temperature of the top of the stripping tower at 105 ℃, feeding volatile organic matter steam at the top of the stripping tower into a condenser, and recovering to obtain organic matters such as methyl chloride, methanol, dimethyl ether and the like, thereby achieving the purpose of partial purification of sulfuric acid; after the tower kettle is purified for the first time, the waste acid enters a No. 1 concentration kettle, vacuum concentration is carried out under the conditions that the absolute pressure is 10kpa and the temperature is 185 ℃, and the mass fraction of the concentrated sulfuric acid is 89.2%; and (3) adding the kettle liquid into an oxidation kettle, slowly dropwise adding 10g (mass fraction is 30%) of hydrogen peroxide, carrying out oxidation treatment under the condition that the temperature and the absolute pressure are kept unchanged, staying for 10min, then adding the mixture into a No. 2 concentration kettle, carrying out vacuum concentration under the conditions that the absolute pressure is 3kpa and the temperature is 195 ℃, obtaining a light yellow transparent clear finished product sulfuric acid, and detecting that the mass fraction of the sulfuric acid is 96.8% and the COD is 219mg/l.
Example 3
And (2) taking the waste acid and steam according to a certain proportion to dilute in a dilution tank, wherein the mass fraction of the diluted acid is 45%, and the diluted acid enters a stripping tower (filled with glass spring packing, the size of the stripping tower:
the size of the filler: diameter of
Length 10-20 mm). Blowing preheated air from the bottom, maintaining the temperature of the top of the stripping tower at 110 ℃, introducing volatile organic matter steam at the top of the stripping tower into a condenser, and recovering to obtain methyl chloride and methanolOrganic matters such as dimethyl ether and the like, so as to achieve the purpose of partial purification of sulfuric acid; after the tower kettle is purified for the first time, the waste acid enters a No. 1 concentration kettle, vacuum concentration is carried out under the conditions that the absolute pressure is 8kpa and the temperature is 180 ℃, and the mass fraction of the concentrated sulfuric acid is 89.7%; and (3) adding the kettle liquid into an oxidation kettle, slowly dropwise adding 15g (mass fraction is 30%) of hydrogen peroxide, carrying out oxidation treatment under the condition that the temperature and the absolute pressure are kept unchanged, staying for 20min, then adding the mixture into a 2# concentration kettle, carrying out vacuum concentration under the conditions that the absolute pressure is 6kpa and the temperature is 210 ℃, obtaining a light yellow transparent clear finished product sulfuric acid, and detecting that the mass fraction of the sulfuric acid is 96.2% and the COD is 246mg/l.
Example 4
And (2) taking the waste acid and distilled water according to a certain proportion, diluting in a diluting tank, wherein the mass fraction of the diluted acid is 41%, and the diluted acid enters a stripping tower (filled with glass spring packing, size of the stripping tower:
the size of the filler: diameter of
Length 10-20 mm). Blowing preheated nitrogen from the bottom, maintaining the temperature at the top of the stripping tower at 120 ℃, and introducing volatile organic matter steam at the top of the stripping tower into a condenser to recover organic matters such as methyl chloride, methanol, dimethyl ether and the like, thereby achieving the purpose of partial purification of sulfuric acid; after the tower kettle is purified for the first time, the waste acid enters a No. 1 concentration kettle, vacuum concentration is carried out under the conditions that the absolute pressure is 7kpa and the temperature is 175 ℃, and the mass fraction of the concentrated sulfuric acid is 88.8%; and (3) adding the kettle liquid into an oxidation kettle, slowly dropwise adding 10g (mass fraction is 65%) of nitric acid, performing oxidation treatment under the condition that the temperature and the absolute pressure are kept unchanged, staying for 20min, then adding the nitric acid into a No. 2 concentration kettle, performing vacuum concentration under the conditions that the absolute pressure is 4kpa and the temperature is 200 ℃, obtaining a light yellow transparent clear finished product sulfuric acid, and detecting that the mass fraction of the sulfuric acid is 96.3% and the COD is 237mg/l.
Example 5
And (2) taking the waste acid and distilled water according to a certain proportion, diluting in a diluting tank, wherein the mass fraction of the diluted acid is 44%, and the diluted acid enters a stripping tower (filled with glass spring packing, size of the stripping tower:
the size of the filler: diameter of
Length 10-20 mm). Blowing preheated air from the bottom, maintaining the temperature of the top of the stripping tower at 115 ℃, feeding volatile organic matter steam at the top of the stripping tower into a condenser, and recovering to obtain organic matters such as methyl chloride, methanol, dimethyl ether and the like, thereby achieving the purpose of partial purification of sulfuric acid; after the tower kettle is purified for the first time, the waste acid enters a No. 1 concentration kettle, vacuum concentration is carried out under the conditions that the absolute pressure is 6kpa and the temperature is 172 ℃, and the mass fraction of the concentrated sulfuric acid is 89.0%; and (3) adding the residue into an oxidation kettle, slowly dropwise adding 20g (mass fraction is 30%) of hydrogen peroxide, carrying out oxidation treatment under the condition that the temperature and the absolute pressure are kept unchanged, standing for 30min, then adding the residue into a No. 2 concentration kettle, carrying out vacuum concentration under the conditions that the absolute pressure is 2kpa and the temperature is 185 ℃, obtaining a light yellow transparent clear finished product sulfuric acid, and detecting that the mass fraction of the sulfuric acid is 96.1% and the COD is 254mg/l.
Comparative example 1
The waste acid and hydrogen peroxide are subjected to oxidation and decoloration reaction at normal temperature according to the mass ratio of 10 to 1 (the mass fraction of hydrogen peroxide is 30%), and the reaction solution after full reaction enters a stripping tower from the top at a metering rate of 1.0L/h. Blowing preheated air from the bottom, maintaining the temperature of the top of the stripping tower at 110 ℃, introducing volatile organic matter steam at the top of the stripping tower into a condenser, and recovering to obtain organic matters, thereby achieving the purpose of partial purification of sulfuric acid; and (3) partial purified waste acid at the tower kettle enters a concentration kettle, vacuum concentration is carried out under the conditions that the absolute pressure is 4kpa and the temperature is 200 ℃ to obtain black finished sulfuric acid, the mass fraction of the black finished sulfuric acid is 96.4 percent and the COD is 18525mg/l, the removal of organic matters is incomplete, and the purification is not thorough enough.
Comparative example 2
The waste acid is purified and concentrated by waste sulfuric acid according to the method disclosed by the patent CN 109721035A; firstly, mixing waste acid with hydrogen peroxide with the mass fraction of 20%, absorbing and treating the generated tail gas, and fully reacting the mixed solution in a stirring reactor to obtain colorless clear transparent liquid; and then removing acid impurities through membrane filtration, enabling obtained filtrate to enter the top of a stripping tower, performing gas-liquid exchange with water vapor in a countercurrent mode, enabling acid flowing out of the bottom of the tower to enter a concentration kettle, performing vacuum concentration under the condition of-0.02 MPa, enabling obtained finished sulfuric acid to be black, and detecting that the mass fraction of the sulfuric acid is 96.3% and the COD is 27480mg/l, so that the waste acid cannot be effectively purified.
Other undescribed parts of the invention are implemented using prior art techniques.
It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and all equivalent substitutions or substitutions made on the above-mentioned embodiments are included in the scope of the present invention.
Claims (3)
1. A method for recycling organic silicon waste acid is characterized by comprising the following steps:
the organic silicon waste acid comprises the following components: 75% of sulfuric acid, 5% of water, 10% of dimethyl ether, 3% of methanol and 2% of methyl sulfate; the chloromethane and the siloxane are both trace;
step 1, diluting the waste acid liquor by using water or water vapor; the mass fraction of the diluted waste sulfuric acid is between 40 and 50 percent;
step 2, adopting preheated air or nitrogen to carry out air stripping treatment on the diluted sulfuric acid; the temperature of the top of the stripping tower is not lower than 100 ℃;
step 3, performing sectional concentration treatment on the waste acid subjected to the stripping treatment under a vacuum condition, and adding an oxidant for oxidation treatment after the first-stage concentration; then, through two-stage concentration, the mass fraction of the sulfuric acid reaches more than 96 percent; the vacuum condition of the first-stage concentration is that the absolute pressure is 6-12 kpa, the temperature is 170-190 ℃, and the mass fraction of the concentrated sulfuric acid is 88-90%; the oxidant is any one of nitric acid or hydrogen peroxide; the vacuum condition of the two-stage concentration is that the absolute pressure is 2-6 kpa, the temperature is 185-210 ℃, and the mass fraction of the concentrated sulfuric acid is more than or equal to 96 percent.
2. The method for recycling organic silicon waste acid as claimed in claim 1, wherein in the step 3, the temperature and the absolute pressure during oxidation are consistent with the operating conditions during the first-stage concentration.
3. The method for recycling the organosilicon waste acid as claimed in claim 1, wherein in the step 3, the oxidation retention time is 5-30 min.
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| CN114920206B (en) * | 2022-05-23 | 2023-11-17 | 江西蓝星星火有机硅有限公司 | Process for removing siloxane in dilute sulfuric acid by continuous method |
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