CN110787484B - Alkali washing and alkali washing wastewater treatment process for 2-ethyl anthraquinone closed-loop extraction liquid - Google Patents
Alkali washing and alkali washing wastewater treatment process for 2-ethyl anthraquinone closed-loop extraction liquid Download PDFInfo
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Abstract
The invention discloses an alkali washing and alkali washing wastewater treatment process for 2-ethyl anthraquinone closed-loop extract liquor. The core of the novel alkali washing process is to strictly control the alkali washing process to have the lowest alkali content on the premise of ensuring the alkali washing effect; meanwhile, an advanced alkali washing external circulation system is designed, the mass transfer effect of oil and water phases is improved, the alkali washing temperature and the retention time are optimized, and the alkali washing effect of an extraction oil layer is improved to a greater extent. The layered water phase obtained by the alkali washing process is light purple red, clear and transparent in appearance; the COD value was about 12000 mg/L. Treating the alkaline washing wastewater in a simple flocculation way, and reducing the COD value to about 3000 mg/L; the appearance also turned to clear and transparent, slightly yellowish. The flocculation press filtration water is assisted with biochemical treatment, the COD value can be reduced to be below 100mg/L, the alkali washing wastewater can be discharged after reaching the standard, and the problem that the alkali wastewater is difficult to treat in the domestic anthraquinone production industry for a long time is completely solved.
Description
Technical Field
The invention relates to an alkaline washing process technology for improving closed-loop extraction liquid in the existing production process of anthraquinone, and fundamentally changes the composition and treatment mode of alkaline washing wastewater, in particular to an alkaline washing and alkaline washing wastewater treatment process for 2-ethyl anthraquinone closed-loop extraction liquid.
Background
The production of 2-ethyl anthraquinone by Friedel-Crafts method currently used in China comprises the following main steps:
1) acylation reaction (Synthesis of 2-ethylbenzoylbenzoic acid aluminum double salt)
In the presence of a reaction solvent, phthalic anhydride, ethyl benzene and aluminum trichloride undergo a condensation reaction to generate 2-ethyl benzoyl benzoic acid aluminum double salt (and a byproduct of hydrogen chloride gas).
2) Hydrolysis reaction (preparation of 2-Ethylbenzoylbenzoic acid (BE acid for short))
The aluminum double salt generated in the condensation reaction in the previous step is subjected to an acid hydrolysis reaction to generate 2-ethyl benzoyl benzoic acid (BE acid).
3) Cyclization reaction and acid precipitation of the solution (preparation of 2-Ethyl anthraquinone (crude product))
Removing the reaction solvent of the BE acid prepared in the hydrolysis reaction, and performing dehydration ring-closing reaction on the BE acid by using fuming sulfuric acid with the SO3 content of about 20%; the ring-closing reaction liquid is subjected to acid precipitation by process water to obtain an acid precipitation liquid containing a crude product of 2-ethyl anthraquinone (hereinafter referred to as anthraquinone).
4) Extraction and alkali washing of acid-out liquid (extraction of 2-ethyl anthraquinone crude product)
Extracting acid-out liquid by an organic solvent according to a certain proportion, wherein anthraquinone in the acid-out liquid is transferred into an organic solvent phase (hereinafter referred to as an oil phase); the aqueous solution containing a large amount of sulfuric acid and a small amount of ring-closure by-products constitutes acidic wastewater (hereinafter referred to as "acidic wastewater") peculiar to the production process of anthraquinones.
The organic solvent oil phase obtained in the extraction process contains a small amount of organic acid (including a small amount of BE acid which is not converted in the ring-closure reaction, and organic sulfonate which is a byproduct in the ring-closure reaction), and needs to BE removed by an alkali washing process, so that the extraction liquid is purified.
5) Comprehensive treatment of acid waste water and alkali washing waste water
In the step 4), acid wastewater and alkaline cleaning wastewater with relatively large total amount are respectively produced. In order to ensure that the whole environment-friendly anthraquinone production process reaches the standard, the comprehensive treatment and standard discharge of the acidic wastewater and the alkaline washing wastewater are also an indestructible ring in the anthraquinone production process.
The invention provides a research result aiming at the problems existing in the alkaline washing process and the comprehensive treatment of alkaline waste water in the production process of anthraquinone; the research on the formation and comprehensive treatment of acidic waste water in the production process of anthraquinone is described in other research results.
In the existing anthraquinone industrial production process, the major problems exist in the alkali washing process and the comprehensive treatment of alkali washing wastewater, and are mainly embodied in the following two aspects:
1. alkali washing process
In the prior anthraquinone production process, a tower type intermittent alkali washing process is adopted. That is, an alkali solution having a sodium hydroxide content of 10% is previously added to the lower half of the alkaline washing packed tower, and then an extraction oil layer is introduced to the bottom of the alkaline washing packed tower. Due to the effect of the density difference, the extract liquid dispersed into droplets passes upwards through the alkaline liquid layer at the bottom of the alkaline washing tower, and acidic substances are removed in the process, so that the extract liquid is subjected to alkaline washing.
2. Production of alkaline washing wastewater
In the alkali washing process, as the alkali washing process is carried out, the sodium hydroxide content in alkali liquor filled in advance at the bottom of the alkali washing tower is continuously reduced, the contents of inorganic salt and organic acid sodium salt in the alkali liquor are continuously increased, the viscosity of the alkali liquor at the bottom of the tower is rapidly increased, and the alkali washing efficiency is deteriorated.
Therefore, when the alkaline washing process has proceeded to a certain extent, the alkaline washing lye has to be replaced: and discharging the invalid alkali liquor, replacing and adding fresh alkali liquor, and starting a new alkali washing process.
From the above, it can be seen that the alkali washing process belongs to a discontinuous alkali washing process: with the continuous progress of the alkali washing process, the concentration of sodium hydroxide in alkali liquor added in advance at the lower section of the alkali washing tower is lower and lower, the contents of inorganic salt (sodium sulfate) and organic acid sodium salt in the formed alkali washing wastewater are higher and higher, the COD value of an alkali washing water layer is rapidly increased, the viscosity of an alkali washing water phase is rapidly increased, the appearance color is close to deep black, the fluidity and the mass transfer performance are deteriorated, the alkali washing process under the normal condition cannot be finished, and the alkali washing process needs to be stopped temporarily to replace fresh alkali liquor.
Typical characteristic data of the alkaline washing wastewater which is failed in the process are shown in a table I in the attached figure 2 of the specification and a typical alkaline wastewater characteristic data table in the prior anthraquinone production process.
As can be seen from the characteristic data of the alkaline wastewater shown in the attached figure 2, the alkaline wastewater has extremely high pollution characteristics, namely extremely high COD (more than 14 ten thousand) value and very high salt content (comprising inorganic salt and organic acid sodium salt); therefore, the alkaline waste water cannot be treated by a biochemical method, and is difficult to realize a harmless treatment scheme such as a waste liquid incineration method, and is the most difficult waste water to treat in the production process of the anthraquinone.
Disclosure of Invention
The invention provides an alkali washing and alkaline wastewater treatment process of 2-ethyl anthraquinone closed-loop extract, aiming at the problems and disadvantages in the alkali washing process and the alkali washing wastewater treatment in the prior anthraquinone production process.
The technical scheme adopted by the invention is as follows: the alkaline washing and alkaline wastewater treatment process of the 2-ethyl anthraquinone closed-loop extraction liquid is characterized by comprising the following steps of:
(1) establishing an alkali washing external circulation system: an alkali washing kettle, an alkali washing external circulating pump, an external circulating heater and a mixer form an alkali washing external circulating system; introducing the extraction oil layer into an alkali liquor mixer (M-1) and fully mixing the extraction oil layer with an external circulation main fluid; the alkaline washing liquid alkali is introduced into a static mixer (M-2), and the alkaline washing liquid alkali is effectively mixed with the main fluid and is further mixed under the action of a subsequent external circulation pump impeller.
(2) The oil and water system which finishes the alkali washing treatment in the external circulation system overflows to a layering kettle, and alkaline wastewater and an alkali washing oil layer are separated; wherein, the alkaline waste water is sent to a flocculation process, and the alkaline oil washing layer is sent to a solvent removal process after being washed by water.
(3) And (3) alkaline wastewater treatment: leading the alkaline wastewater to a flocculation kettle, neutralizing the alkaline wastewater to be neutral by using sulfuric acid, and then adding a general-purpose flocculant for flocculation treatment; after the flocculation mud is removed by pH value adjustment and filtration, the filtered water is sent to a biochemical treatment device; after biochemical treatment, the wastewater is discharged after reaching standards, or returned to the acidification process to be used as closed-loop liquid dilution water for closed-loop recycling.
Further, in the alkali washing external circulation process in the step (1), the circulation volume ratio range of the circulation liquid to the feeding material of the extraction oil layer is 3: 1-10: 1; the alkali washing temperature of the external circulation process is 60-90 ℃, and the average residence time of the extraction oil layer in the alkali washing external circulation system is 3-20 minutes.
Further, the alkali used in the alkali washing liquid is inorganic alkali.
Further, the inorganic base is sodium hydroxide.
Further, the sodium hydroxide in the alkali washing alkali liquor is excessive, and the range of the sodium hydroxide in the alkali wastewater is controlled to be between 0.1 and 0.5 percent; the mass fraction of the sulfuric acid is 5-20%, the alkaline washing wastewater is neutralized to be neutral by using the sulfuric acid, and the subsequent wastewater treatment with the salt content of 0.18-0.88% is easy to carry out.
Further, in the step of treating the alkaline wastewater in the step (3), the flocculant is an inorganic flocculant free of chloride ions, or the flocculant is an inorganic flocculant free of chloride ions and an auxiliary organic flocculant.
Further, in the step of treating the alkaline wastewater in the step (3), the flocculant is polyacrylamide and polymeric ferric sulfate, or the flocculant is polyacrylamide and polymeric aluminum sulfate.
Further, in the step of treating the alkaline wastewater in the step (3), the adding amount and the ratio of the flocculating agent are as follows: polymeric ferric sulfate or polymeric aluminum sulfate: the weight of the total amount of the alkaline wastewater is 0.01-0.1%: 1; polyacrylamide: the weight ratio of the total amount of the alkali washing wastewater is 0.1-0.5 ‰: 1.
further, in the step of treating the alkaline wastewater in the step (3), after the flocculation process is completed, adding an inorganic alkali liquor, adjusting the pH value of the flocculation liquid to be neutral, carrying out filter pressing by using filter pressing equipment, sending the obtained flocculated sludge to a waste solid treatment station, carrying out filter pressing to obtain filter pressing wastewater with a COD value of about 2000-4000 mg/L, and sending the filter pressing wastewater to a sewage biochemical treatment device for treatment, wherein the COD value of the filter pressing wastewater is reduced to be less than 100 mg/L; discharging 20-40% of the biochemically treated water to reach the standard, and returning the remaining 80-60% of the treated water to the acid precipitation process to be recycled as process water.
After the method is adopted, the following effects can be achieved:
1. the existing tower type intermittent alkaline washing process is innovated into a continuous kettle type external circulation alkaline washing process, the alkali addition amount in the alkaline washing process is accurately controlled, and the quality of alkaline washing wastewater is greatly improved while the mass transfer efficiency of alkaline washing is improved.
2. The comprehensive characteristics of the alkali washing wastewater are greatly improved, so a flocculation superposition biochemical treatment mode can be simply adopted, and the harmless treatment of the alkali washing wastewater is carried out by a simplified process. The wastewater after biochemical treatment is discharged after reaching the standard; or returning to the main process system to realize the comprehensive utilization closed cycle of the alkali washing wastewater.
3. Saving resources, protecting the environment, improving the production efficiency and improving the economic benefits of enterprises.
Drawings
FIG. 1 is a process flow diagram of the present invention.
FIG. 2 is a table-data diagram of the present invention.
FIG. 3 is a table two data diagram of the present invention.
FIG. 4 is a table three data diagram of the present invention.
FIG. 5 is a table four data chart of the present invention.
Detailed Description
The invention is described in detail below with reference to the figures and examples.
Example 1
An alkaline washing and alkaline wastewater treatment process for 2-ethyl anthraquinone closed-loop extract liquor is characterized by comprising the following steps:
(1) establishing an alkali washing external circulation system: an alkali washing kettle, an alkali washing external circulating pump, an external circulating heater and a mixer form an alkali washing external circulating system; introducing the extraction oil layer into an alkali liquor mixer, and fully mixing the extraction oil layer with an external circulation main fluid; the alkaline washing liquid alkali is introduced into the static mixer, and the alkaline washing liquid alkali is effectively mixed with the main fluid and is further mixed under the action of a subsequent external circulation pump impeller.
(2) The oil and water system which finishes the alkali washing treatment in the external circulation system overflows to a layering kettle, and alkaline wastewater and an alkali washing oil layer are separated; wherein, the alkaline waste water is sent to a flocculation process, and the alkaline oil washing layer is sent to a solvent removal process after being washed by water.
(3) And (3) alkaline wastewater treatment: leading the alkaline wastewater to a flocculation kettle, neutralizing the alkaline wastewater to be neutral by using sulfuric acid, and then adding a general-purpose flocculant for flocculation treatment; after the flocculation mud is removed by pH value adjustment and filtration, the filtered water is sent to a biochemical treatment device; after biochemical treatment, the wastewater is discharged after reaching standards, or returned to the acidification process to be used as closed-loop liquid dilution water for closed-loop recycling.
Further, in the alkali washing external circulation process in the step (1), the circulation volume ratio range of the circulation liquid to the feeding material of the extraction oil layer is 3: 1-10: 1; the alkali washing temperature of the external circulation process is 60-90 ℃, and the average residence time of the extraction oil layer in the alkali washing external circulation system is 3-20 minutes.
Further, the alkali used in the alkali washing liquid is inorganic alkali.
Further, the inorganic base is sodium hydroxide.
Further, the sodium hydroxide in the alkaline washing alkali liquor is excessive, and the range of the sodium hydroxide in the alkaline wastewater is controlled to be between 0.1 and 0.5 percent; the mass fraction of the sulfuric acid is 5-20%, the alkaline washing wastewater is neutralized to be neutral by using the sulfuric acid, and the subsequent wastewater treatment with the salt content of 0.18-0.88% is easy to carry out.
Further, in the step of treating the alkaline wastewater in the step (3), the flocculating agent is an inorganic flocculating agent without chloride ions, or the flocculating agent is an inorganic flocculating agent without chloride ions and an auxiliary organic flocculating agent.
Further, in the step of treating the alkaline wastewater in the step (3), the flocculating agent is polyacrylamide and polymeric ferric sulfate, or the flocculating agent is polyacrylamide and polymeric aluminum sulfate.
Further, in the step of treating the alkaline wastewater in the step (3), the adding amount and the ratio of the flocculating agent are as follows: polymeric ferric sulfate or polymeric aluminum sulfate: the weight of the total amount of the alkaline wastewater is 0.01-0.1%: 1; polyacrylamide: the weight ratio of the total amount of the alkali washing wastewater is 0.1-0.5 ‰: 1.
further, in the step (3) of treating the alkaline wastewater, after the flocculation process is finished, adding an inorganic alkali liquor, adjusting the pH value of the flocculation liquid to be neutral, carrying out filter pressing by using filter pressing equipment, sending the obtained flocculated sludge to a waste solid treatment station, carrying out filter pressing to obtain filter pressing wastewater with the COD value of about 2000-4000 mg/L, and sending the filter pressing wastewater to a sewage biochemical treatment device for treatment, wherein the COD value of the filter pressing wastewater is reduced to be less than 100 mg/L; discharging 20-40% of the biochemically treated water to reach the standard, and returning the remaining 80-60% of the treated water to the acid precipitation process to be recycled as process water.
Example 2
A new process for alkali washing of 2-ethyl anthraquinone closed-loop extract liquor and treatment of alkaline wastewater is characterized by comprising the following steps:
(1) alkali washing external circulation system: an alkali washing external circulation system is formed by an alkali washing kettle, an alkali washing external circulation pump, an external circulation heater and a mixer, so that the mixing efficiency and the mass transfer effect of alkali washing oil and water are greatly improved; the process comprises the following steps: introducing the extraction oil layer into an alkali liquor mixer, and fully mixing the extraction oil layer with an external circulation main fluid; and the alkaline washing liquid alkali is introduced into the static mixer, and is effectively mixed with the main fluid, and is further mixed under the action of a subsequent external circulation pump impeller.
(2) The oil and water system which finishes the alkali washing treatment in the external circulation system overflows to a layering kettle, and alkaline wastewater and an alkali washing oil layer are separated; wherein, the alkaline waste water is sent to a flocculation process, and the alkaline oil washing layer is sent to a solvent removal process after being washed by water.
(3) And (3) alkaline wastewater treatment: leading the alkaline wastewater to a flocculation kettle, neutralizing the alkaline wastewater to be neutral by using trace sulfuric acid, and then adding a general-purpose flocculating agent for flocculation treatment; after the flocculation mud is removed by pH value adjustment and filtration, the filtered water is sent to a biochemical treatment device; after biochemical treatment, the wastewater is discharged after reaching standards, or returned to the acidification process to be used as closed-loop liquid dilution water for closed-loop recycling.
Further, in the alkali washing external circulation process in the step (1), the circulation ratio (circulation liquid: extraction oil layer feeding) =3: 1-10: 1 (volume ratio); the alkali washing temperature of the external circulation process is 60-90 ℃, and the average residence time of the extraction oil layer in the alkali washing external circulation system is 3-20 minutes.
Further, the alkaline wash liquors described herein, wherein the alkali used is an inorganic alkali, including but not limited to: and alkaline compounds such as sodium hydroxide, potassium hydroxide, and calcium hydroxide. For convenience of description, sodium hydroxide is used as an example for illustration.
Furthermore, the core technology of the embodiment is that the sodium hydroxide micro-excess in the alkaline washing alkali liquor is strictly controlled, so that the alkali demand in the alkaline washing process can be ensured, the residual sodium hydroxide excess rate after the alkaline washing process is finished is very little, and the range is controlled between 0.1% and 0.5%; then 5 to 20 percent of dilute sulphuric acid is used for neutralizing the alkaline washing layered wastewater to be neutral, and the salt content (calculated by sodium sulfate) in the wastewater is 0.18 to 0.88 percent (weight percentage); therefore, the alkaline wastewater obtained by the process has extremely low inorganic salt content, and is easy to carry out subsequent wastewater treatment.
Further, in the step (3), the flocculant is a flocculant which does not contain chloride ions, such as polymeric ferric sulfate, polymeric aluminum sulfate and the like (a trace amount of organic flocculant is added in an auxiliary manner if necessary); the addition amount of the flocculating agent is as follows:
polymeric ferric sulfate (polymeric aluminum sulfate): the total amount of the alkaline wastewater =0.01% -0.1%: 1 (weight ratio);
polyacrylamide: the total amount of the alkaline washing wastewater is = 0.1-0.5 ‰: 1.
further, in the alkaline wastewater treatment method in the step (3), after the flocculation process is completed, a trace amount of inorganic alkali liquor is added, the pH value of the flocculation liquid is adjusted to be neutral, the flocculation sludge is subjected to pressure filtration by a pressure filtration device, the obtained flocculation sludge is sent to a waste solid treatment station, and after the pressure filtration wastewater (the COD value is about 2000-4000 mg/L) is sent to a sewage biochemical treatment device for treatment, the COD value is reduced to be below 100 mg/L; 20-40% of the biochemically treated water is discharged after reaching the standard, and the remaining 80-60% of the treated water is returned to the acid precipitation process to be recycled as process water, so that the addition of fresh process water is greatly reduced.
Example 3
An alkali washing external circulation enlarging small test device is constructed according to the attached figure 1, and the embodiment takes continuous and stable operation for two hours as a data measuring unit.
Adding enough toluene in advance to enable the toluene to overflow naturally at a discharge port; starting an external circulation pump, and establishing normal external circulation operation; heating steam is introduced into the jacket of the alkaline washing kettle, and the temperature of the alkaline washing kettle is controlled to be 80-85 ℃.
Subsequently, introducing an alkaline washing lye into a static mixer at the suction end of the circulating pump; the adding amount of alkaline washing lye is 10L/hr, wherein the content of sodium hydroxide is set to be 0.65%; alkali washing alkali liquor is mixed with an external circulation main fluid in a static mixer, enters a circulating pump body together, and is fully mixed again under the action of the shearing force of a high-speed rotating impeller, so that the mass transfer efficiency in the alkali washing process is greatly improved.
When introducing alkali washing liquid, introducing an extraction oil layer at an inlet of a special mixer arranged in an alkali washing kettle, and mixing the extraction oil layer with a main fluid flowing at a high speed to carry out efficient alkali washing.
In this example, the amount of the extract added was set to 20L/hr, and the flow rate ratio to the alkaline washing aqueous phase was 2:1 (volume ratio); the material circulation ratio is 5:1 (volume ratio), and the average residence time of the alkali washing material is 12-15 minutes.
Layering the alkali washing mixed liquor by a separator, collecting an obtained oil layer, and removing the solvent toluene by distillation to obtain an anthraquinone crude product.
In the time unit of two hours of stable operation of this example, 40 liters of extract and 20 liters of alkali washing lye are added together; 5.75kg of anthraquinone crude product is finally obtained, and compared with the original alkali washing process, the appearance, the content and the yield are all improved.
15.5kg of alkaline waste water is separated out in the experiment and neutralized to neutrality by 10 percent of dilute sulfuric acid. The appearance of the neutralized liquid is dark orange red, and the neutralized liquid is slightly turbid and semitransparent liquid; the content of inorganic salt was found to be 1.0%, and the COD value was 12000 mg/L.
The above-mentioned alkaline washing wastewater was treated in a laboratory batch mode.
Transferring the neutralized water layer into 2000ml three-mouth glass reaction bottle in batches, adding polymeric ferric sulfate (liquid) accounting for 0.15% of the total amount of the alkaline wastewater and polyacrylamide flocculant accounting for 0.33 per mill of the total amount of the alkaline wastewater respectively under stirring, and maintaining the flocculation stirring for about 10 minutes; then removing flocculated mud by adopting a vacuum filtration method to obtain tea yellow alkali washing and filtration wastewater with the total amount of 14.8kg and the COD value of 1470 mg/L; finally, clear and transparent alkaline washing process final treatment water with the COD value of 92mg/L is obtained by a common biochemical treatment method, and the final treatment water meets the national first-level discharge standard of wastewater treatment.
Example 4
The following parameters were adjusted and compared under exactly the same conditions as described in example 3 for the alkaline cleaning process:
1) adjusting the alkali washing temperature from 80-85 ℃ to 65-70 ℃; experimental results show that the appearance of the obtained crude anthraquinone is changed from pure yellow to slightly earthy yellow, which indicates that the alkali washing of the organic acid is incomplete in the alkali washing process and influences the quality of the crude anthraquinone.
2) The circulation ratio of the alkaline washing external circulation is adjusted from 5:1 to 3: 1; the experimental result shows that under the condition of other unchanged conditions, the circulation ratio is reduced, the mass transfer effect of an external circulation system is reduced, and the quality of the crude anthraquinone product is also influenced to a certain extent.
3) And respectively comparing the alkali washing effects by adopting the alkali washing alkali liquor with the sodium hydroxide content of 2% and 0.45%. In the former, the addition amount of sodium hydroxide is far higher than the demand amount of sodium hydroxide in alkaline washing neutralization reaction, and excessive sodium hydroxide is neutralized by sulfuric acid to generate sodium sulfate before flocculation, so that the content of inorganic salt in the flocculation filter-pressing wastewater is greatly increased (up to more than 2.5 percent), and the subsequent biochemical treatment difficulty of the wastewater is increased; for the latter, the alkali washing system is in a weak acid state due to insufficient dosage of the added sodium hydroxide, so that the alkali washing process of the extract is incomplete, and the quality of the anthraquinone crude product is influenced.
Description and supplementation of the principles and detailed parameters of the present invention:
according to the research result provided by the invention, the alkali consumption in the alkali washing process can be controlled and reduced while the alkali washing efficiency is improved and the mass transfer effect is optimized, the content of inorganic salt in the alkali washing wastewater is greatly reduced (less than or equal to 0.5 percent), and the quality of the alkali washing wastewater is greatly improved, so that the alkali washing wastewater is changed from being incapable of being treated into being easily and comprehensively treated; therefore, the method has very important significance for realizing green and environment-friendly anthraquinone production.
In order to change the alkali washing process and the alkali washing wastewater characteristic in the anthraquinone production process, the invention changes the discontinuous alkali washing tower in the prior anthraquinone industrial production into an external circulation continuous kettle type alkali washing process, and two groups of feed mixers are arranged in the new process, so that the alkali washing mass transfer efficiency can be greatly improved (see a new process schematic diagram provided in figure 1).
On the basis of improving the alkali washing efficiency and ensuring the alkali washing effect, the alkali content in the alkali washing liquid is greatly reduced, and therefore, the inorganic salt content in the final alkali washing wastewater is greatly reduced.
Alkali washing waste water is separated from the alkali washing mixed liquor sent out from the external circulation system in a standing and layering mode, and is neutralized to be neutral by trace dilute sulfuric acid, and then flocculating agent is added; removing flocculated mud in the alkaline washing wastewater in a filter pressing mode, sending the obtained filter pressing water to a sewage treatment system, performing biochemical treatment, or discharging after reaching the standard, or returning to an acid precipitation process, and using the filter pressing water as process water for closed-circuit recycling, so that the consumption of fresh process water can be greatly reduced.
The method specifically comprises the following steps and principles:
1. an alkaline washing external circulation system is established, which mainly comprises:
1) an external circulation alkaline washing kettle with an extract liquid feeding mixer, wherein the alkaline washing kettle is provided with a steam heating jacket to adjust and control the alkaline washing temperature;
2) an external circulating pump is arranged to provide external circulating power for the system;
3) an alkaline washing lye feed mixer is arranged at the inlet end of the external circulating pump.
2. The working principle of the alkaline washing external circulation system (see the attached figure 1):
1) in the first run, the crude extract is first extracted with pure extractant (e.g.: toluene) fills an alkali washing external circulation system, and normal external circulation operation is established;
2) the alkaline washing water is introduced into a static mixer at the inlet end of the external circulating pump and is well mixed with the main fluid of the circulating liquid, and the alkaline washing water is subjected to mass transfer and heat transfer;
3) introducing the feed of the extraction oil phase into a special mixer of an alkaline washing kettle, fully mixing with the circulating liquid, and carrying out good mass transfer and heat transfer with a main fluid of the circulating liquid;
4) accurately designing and controlling the average residence time of the extraction oil phase and the alkaline washing water in an alkaline washing external circulation system, and overflowing an alkaline washing completion liquid from the upper part of the alkaline washing kettle after the corresponding average residence time is reached.
3. The technological parameters of the alkali washing external circulation system are as follows:
1) ratio of alkali washing oil to water
In the alkaline washing external circulation system, the appropriate proportion range of the extraction oil phase and the alkaline washing water phase is as follows:
extracting an oil phase: an alkaline washing water phase (volume ratio) =200: 100-300: 100;
2) the content of sodium hydroxide in the alkaline washing alkali liquor is determined according to the alkali consumption of acidic substances in the extracted oil phase during alkaline washing neutralization; namely: after the neutralization of acidic substances in the extraction oil phase is ensured to be finished, the alkali washing system is strongly alkaline due to the existence of slightly excessive sodium hydroxide;
the process design is one of the cores of the invention: not only can ensure complete alkali cleaning, but also avoids the alkali cleaning waste water containing a large excess of inorganic salt after neutralization;
in the invention, the sodium hydroxide content range in the alkali washing alkali liquor is as follows: 0.4% -1.2%;
3) circulation ratio of external circulation system
The circulation ratio of an external circulation system (circulation liquid: feeding of an extraction oil layer) =3: 1-10: 1 (volume ratio);
4) alkali wash temperature of external circulation system
Under the condition of lower alkali washing concentration, the designed alkali washing temperature is kept higher, which is beneficial to the completion of the neutralization reaction of organic acid in the extraction liquid.
The alkali washing temperature range of the external circulation system is 60-90 ℃;
5) mean residence time of materials in alkaline washing external circulation system
In order to ensure complete alkali washing of the extraction liquid, a reasonable material average residence time range must be designed and controlled; the average retention time of the materials is mainly determined by the volume of the alkaline washing kettle and the circulation frequency of the external circulation system in unit time of the alkaline washing materials;
corresponding to the invention, the average residence time of the materials in the alkaline washing external circulation system is in the range of 2 minutes to 20 minutes.
4. Treatment of alkaline washing waste water
According to the optimized alkali washing process, the obtained alkali washing wastewater is substantially changed from the appearance or the inherent pollution characteristic; the characteristics of the alkali washing wastewater obtained by the new alkali washing process are shown in a table II in an attached figure 3 of the specification and a characteristic table of the alkali washing wastewater of the new alkali washing process.
As can be seen from the attached figure 3, although the total amount of the alkali washing wastewater is increased by about 2 times compared with the prior anthraquinone production process, the pollution characteristic of the alkali washing wastewater obtained by the new alkali washing process is greatly reduced, particularly the content of inorganic salts in the alkali washing wastewater is reduced by more than 20 times, and the COD value of the wastewater is reduced by more than 10 times, so that the treatability of the alkali washing wastewater is greatly improved, and the original treatment failure is changed into the treatment of simpler and more common wastewater to be well treated.
The alkali washing wastewater of the new process can be well treated according to the following steps:
neutralization and flocculation of alkaline washing wastewater
The layered alkaline washing wastewater from the alkaline washing process has a COD value of 10000-20000 and is strongly alkaline due to the fact that the wastewater contains trace sodium hydroxide (see attached figure 3).
Dilute sulfuric acid (with the concentration of 5% -10%) is adopted to neutralize the alkaline waste water to neutrality.
In the neutralization step, the sodium hydroxide content of the wastewater is extremely low (usually 0.2-0.4%), so that the inorganic salt content of the wastewater after the neutralization reaction is only slightly increased, and the comprehensive treatment of the wastewater is hardly influenced.
Proper amounts of polymeric ferric sulfate and polyacrylamide are respectively added into the neutralized alkali washing wastewater, so that organic impurities contained in the alkali washing wastewater can be well flocculated, and the subsequent treatment of the wastewater is facilitated.
The flocculation conditions adopted by the invention are as follows:
amount of polymeric ferric sulfate (liquid): 1-5 per mill of the mass of the alkali washing wastewater;
the dosage of polyacrylamide is as follows: 0.1-0.5 per mill of the mass of the alkaline washing wastewater;
flocculation temperature: 40-80 ℃;
flocculation time: 10 minutes to 1 hour.
After the flocculation process is finished, removing the flocculated mud (the output of the flocculated mud is about 0.8-1.2 percent (wet basis) of the total amount of the alkali washing wastewater) by a filter pressing mode, and conveying the flocculated mud to solid waste landfill treatment; the characteristic data of the filter pressing water obtained in the filter pressing process are shown in the table III of the attached figure 4 of the specification: the flocculation filter pressing alkali washing wastewater is characterized in the specification.
The characteristics of the alkaline washing wastewater can be seen from the attached figure 4, and the alkaline washing new process is changed substantially: through simple flocculation treatment, the pollution characteristic is greatly reduced, and the method accords with direct biochemical treatment conditions.
The characteristics of the water after biochemical treatment are shown in the fourth table of the attached figure 5 of the specification and the characteristic data after the biochemical treatment of the flocculation press filtration water.
As shown in the attached figure 5, the alkali washing wastewater after biochemical treatment meets the national first-level discharge standard, and closed circulation or standard discharge of the wastewater can be realized.
Claims (9)
1. An alkaline washing and alkaline wastewater treatment process for 2-ethyl anthraquinone closed-loop extract liquor is characterized by comprising the following steps:
(1) establishing an alkali washing external circulation system: an alkali washing kettle, an alkali washing external circulating pump, an external circulating heater and a mixer form an alkali washing external circulating system; introducing the extraction oil layer into an alkali liquid mixer M-1, and fully mixing the extraction oil layer with an external circulation main fluid; introducing alkaline washing liquid alkali into a static mixer M-2, wherein the alkaline washing liquid alkali is effectively mixed with a main fluid and is further mixed under the action of a subsequent external circulation pump impeller;
(2) the oil and water system which finishes the alkali washing treatment in the external circulation system overflows to a layering kettle, and alkaline wastewater and an alkali washing oil layer are separated; wherein, the alkaline waste water is sent to a flocculation process, and the alkaline oil washing layer is sent to a solvent removal process after being washed by water;
(3) and (3) alkaline wastewater treatment: leading the alkaline wastewater to a flocculation kettle, neutralizing the alkaline wastewater to be neutral by using sulfuric acid, and then adding a general-purpose flocculant for flocculation treatment; after the flocculation mud is removed by pH value adjustment and filtration, the filtered water is sent to a biochemical treatment device; after biochemical treatment, the wastewater is discharged after reaching standards, or returned to the acidification process to be used as closed-loop liquid dilution water for closed-loop recycling.
2. The alkaline washing and alkaline wastewater treatment process of the 2-ethyl anthraquinone closed-loop extract liquor according to claim 1, which is characterized in that: in the alkaline washing external circulation process in the step (1), the circulation volume ratio range of the circulation liquid to the extraction oil layer feeding material is 3: 1-10: 1; the alkali washing temperature of the external circulation process is 60-90 ℃, and the average residence time of the extraction oil layer in the alkali washing external circulation system is 3-20 minutes.
3. The alkaline washing and alkaline wastewater treatment process of the 2-ethyl anthraquinone closed-loop extract liquor, according to claim 2, is characterized in that: the alkali used in the alkali washing liquid is inorganic alkali.
4. The alkaline washing and alkaline wastewater treatment process of the 2-ethyl anthraquinone closed-loop extract liquor, according to claim 3, is characterized in that: the inorganic base is sodium hydroxide.
5. The alkaline washing and alkaline wastewater treatment process of the 2-ethyl anthraquinone closed-loop extract liquor, according to claim 4, is characterized in that: the sodium hydroxide in the alkaline washing alkali liquor is excessive, and the range of the sodium hydroxide in the alkaline waste water is controlled to be between 0.1 and 0.5 percent; the mass fraction of the sulfuric acid is 5-20%, the alkaline washing wastewater is neutralized to be neutral by using the sulfuric acid, and the subsequent wastewater treatment with the salt content of 0.18-0.88% is easy to carry out.
6. The alkaline washing and alkaline wastewater treatment process of the 2-ethyl anthraquinone closed-loop extract liquor, according to claim 4, is characterized in that: in the step of treating the alkaline wastewater in the step (3), the flocculant is an inorganic flocculant without chloride ions, or the flocculant is an inorganic flocculant without chloride ions and an auxiliary organic flocculant.
7. The alkaline washing and alkaline wastewater treatment process of the 2-ethyl anthraquinone closed-loop extract liquor, according to claim 6, is characterized in that: in the step of treating the alkaline wastewater in the step (3), the flocculating agent is polyacrylamide and polymeric ferric sulfate, or the flocculating agent is polyacrylamide and polymeric aluminum sulfate.
8. The alkaline washing and alkaline wastewater treatment process of the 2-ethyl anthraquinone closed-loop extract liquor, according to claim 7, is characterized in that: in the step of treating the alkaline wastewater in the step (3), the addition amount and the ratio of the flocculating agent are as follows: polymeric ferric sulfate or polymeric aluminum sulfate: the weight of the total amount of the alkaline wastewater is 0.01-0.1%: 1; polyacrylamide: the weight ratio of the total amount of the alkali washing wastewater is 0.1-0.5 ‰: 1.
9. the alkaline washing and alkaline wastewater treatment process of the 2-ethyl anthraquinone closed-loop extract liquor, according to claim 4, is characterized in that: in the step (3) of treating the alkaline wastewater, after the flocculation process is finished, adding an inorganic alkali liquor, adjusting the pH value of a flocculation liquid to be neutral, carrying out filter pressing by using filter pressing equipment, sending the obtained flocculated sludge to a waste solid treatment station, carrying out filter pressing to obtain filter pressing wastewater with a COD value of 2000-4000 mg/L, and sending the filter pressing wastewater to a sewage biochemical treatment device for treatment, wherein the COD value of the filter pressing wastewater is reduced to be less than 100 mg/L; discharging 20-40% of the biochemically treated water to reach the standard, and returning the remaining 80-60% of the treated water to the acid precipitation process to be recycled as process water.
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| CN113443977B (en) * | 2021-06-28 | 2023-04-18 | 百色世裕科技股份有限公司 | Sulfur and chlorine removal process in 2-ethyl anthraquinone production |
| CN113979849B (en) * | 2021-11-22 | 2024-03-29 | 浙江金科日化新材料股份有限公司 | Purification process for desulfurizing and dechlorinating 2-ethyl anthraquinone |
| CN113968778B (en) * | 2021-11-22 | 2024-03-29 | 浙江金科日化新材料股份有限公司 | Device and process for continuous water-out extraction phase separation of 2- (4' -ethylbenzoyl) benzoic acid closed-loop liquid by one-step method |
| CN114436800A (en) * | 2022-01-26 | 2022-05-06 | 重庆毂运科技有限公司 | Acid-out alkali-washing separation system and process for 2-ethyl anthraquinone crude product |
| CN114432985A (en) * | 2022-02-18 | 2022-05-06 | 内蒙古恒星化学有限公司 | Method and system for discharging waste alkali liquor in organic silicon production |
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Denomination of invention: A kind of alkaline washing and alkaline washing wastewater treatment process of 2-ethylanthraquinone closed-loop extract Effective date of registration: 20220801 Granted publication date: 20201002 Pledgee: Baise small and Micro Enterprise Financing Guarantee Co.,Ltd. Pledgor: Baise Shiyu Technology Co.,Ltd. Registration number: Y2022450000124 |