CN111072053A - Method for treating raffinate in recovery process of para-aramid solvent - Google Patents

Method for treating raffinate in recovery process of para-aramid solvent Download PDF

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CN111072053A
CN111072053A CN201911107683.XA CN201911107683A CN111072053A CN 111072053 A CN111072053 A CN 111072053A CN 201911107683 A CN201911107683 A CN 201911107683A CN 111072053 A CN111072053 A CN 111072053A
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salt
concentration
raffinate
solution
para
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CN111072053B (en
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曹煜彤
赵开荣
顾克军
陆春明
陈超
张立铭
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Sinochem High Performance Fiber Material Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F11/00—Compounds of calcium, strontium, or barium
    • C01F11/20—Halides
    • C01F11/24—Chlorides
    • C01F11/32—Purification
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D3/00—Halides of sodium, potassium or alkali metals in general
    • C01D3/04—Chlorides
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C02F1/041—Treatment of water, waste water, or sewage by heating by distillation or evaporation by means of vapour compression
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/283—Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
    • Y02P70/62—Manufacturing or production processes characterised by the final manufactured product related technologies for production or treatment of textile or flexible materials or products thereof, including footwear

Abstract

The invention discloses a method for treating raffinate in a para-aramid solvent recovery process, wherein the raffinate contains NaCl and CaCl2And a small amount of NMP, wherein the treatment method comprises the following steps: (1) calcium salt precipitation step: adding a certain amount of soluble carbonate into raffinate to obtain precipitate CaCO3And a salt solution; (2) sodium salt enrichment and concentration step: sending the neutralized salt solution into an organic adsorption system, and removing organic impurities; feeding the solution after impurity removal into a system containing a reverse osmosis membrane to obtain high-concentration salt and fresh water; (3) sodium salt dissolving and recovering step: and (3) sending the high-concentration salt obtained in the step (2) into a multi-effect evaporation system (MVR) to obtain salt crystals. The invention realizes effective separation and recycling of sodium salt and calcium salt, and simultaneously reduces the content of sodium salt and calcium salt by utilizing the prior adsorption method, membrane concentration and MVR technologyProduction cost and environmental pollution.

Description

Method for treating raffinate in recovery process of para-aramid solvent
Technical Field
The invention relates to the technical field related to wastewater treatment, in particular to a method for treating raffinate in a recovery process of a para-aramid solvent.
Background
After the polymerization process of the para-aramid, the polymer powder needs to be neutralized and washed with water, and the mother liquor generated by washing with water contains a recyclable solvent (N-methylpyrrolidone, NMP for short), which is mostly recycled by extraction.
The extracted solvent enters a stripping tower for separation, and the extracted water phase is treated by waste water. The raffinate water phase contains NaCl and CaCl2And a small amount of NMP, which is not in accordance with the environmental protection requirement and causes resource waste. The waste water contains NaCl and can not be directly returned to the polymerization process for continuous use. In the prior part, Ca (OH) is adopted to avoid the substitution of sodium salt2As a neutralizing agent. But due to Ca (OH)2The solubility is not high, and the pipeline is easy to be blocked, so NaOH is still used as a neutralizer in the production. But the sodium salt impurities are necessarily brought into the system. The sodium salt has high solubility and is not easy to separate out, and the literature is less concerned with the treatment scheme of the waste water.
Chinese patent application publication No. CN109134339A discloses a method for recovering para-aramid fiber production, which comprises the steps of adding hydrochloric acid generated by neutralization polymerization of calcium carbonate into a washing liquid obtained after polymerization of PPTA, conveying the neutralized washing liquid into an extraction tower for extraction and separation, conveying an extraction phase to a separation extractant and NMP in a coarse grouping line to obtain a coarse material, adding hot water into the coarse material, conveying the coarse material to a fine separation device for further separation of the extractant to obtain a fine material, conveying the fine material to a fine evaporator for purification and recovery of NMP, carrying out ion displacement and precipitation treatment on a rectification waste liquid, conveying a filtrate to the extraction tower again for extraction and separation after filter pressing to obtain a precipitate, mixing NMP with a calcium chloride aqueous solution, cooling and conveying to a polymerization system to prepare a para-phenylenediamine solution. The patent effectively solves the problems of treatment of material rectification waste liquid and decomposition and acidification of an extracting agent, improves the recovery rate and recovery quality of NMP, and does not influence the stable and continuous operation of solvent recovery production.
In the patent, the salt content of the filtrate pressed out by the filter press is not separated, the filtrate is directly returned to the step 1 and mixed with the neutralized washing liquid, the mixture is extracted and separated by being conveyed to an extraction tower, the precipitate pressed out by the filter press is treated as solid waste, and the treatment mode of the filtrate can cause more and more salt content in the filtrate and can not be discharged out of the system. Secondly, the sediment extruded by the filter press in the patent is treated as solid waste, so that the production cost is increased.
Disclosure of Invention
The invention aims to provide a treatment method of raffinate in a recovery process of a para-aramid solvent, which realizes effective separation and recycling of sodium salt and calcium salt in the raffinate in the recovery process of the para-aramid solvent, and reduces production cost and environmental pollution by using the existing adsorption method, membrane concentration and MVR technology.
In order to realize the purpose of the invention, the adopted technical scheme is as follows:
method for treating raffinate in recovery process of para-aramid solvent, wherein the raffinate contains NaCl and CaCl2And a small amount of NMP, wherein the treatment method comprises the following steps:
(1) calcium salt precipitation step:
adding a certain amount of soluble carbonate into raffinate to obtain precipitate CaCO3And a salt solution;
(2) sodium salt enrichment and concentration step:
sending the neutralized salt solution into an organic adsorption system, and removing organic impurities; feeding the solution after impurity removal into a system containing a reverse osmosis membrane to obtain high-concentration salt and fresh water;
(3) sodium salt dissolving and recovering step:
and (3) sending the high-concentration salt obtained in the step (2) into a multi-effect evaporation system (MVR) to obtain salt crystals.
In a preferred embodiment of the invention, CaCO is obtained in step (1)3Neutralizing with dilute hydrochloric acid to obtain CaCl2The solution can be recovered as a cosolvent to be continuously used for aramid polymerization.
In a preferred embodiment of the invention, the soluble carbonate comprises Na2CO3、NaHCO3、K2CO3、KHCO3Any one or more of them.
In a preferred embodiment of the present invention, the organic adsorption system comprises a carbon adsorption system or a resin adsorption system.
In a preferred embodiment of the invention, the content of the high-concentration salt is 5-15%, and the content of the salt in the fresh water is less than or equal to 0.2%.
In a preferred embodiment of the invention, the concentration of the obtained salt crystals is 60-75%.
The invention has the beneficial effects that:
realizes effective separation and recycling of sodium salt and calcium salt, and reduces production cost and environmental pollution by using the existing adsorption method, membrane concentration and MVR technology. Compared with the recovery method for para-aramid fiber production disclosed by Chinese patent application publication No. CN109134339A, the method can separate the salt in the filtrate in time and can not be brought into the next step. Meanwhile, fresh water can be recycled in the salt separation process, so that the water resource consumption is reduced, and the production cost is further reduced. In addition, the invention does not need to treat solid wastes, and the obtained CaCO3Neutralizing with dilute hydrochloric acid to obtain CaCl2The solution can be recycled as a cosolvent and can be continuously used for aramid polymerization, so that the solid waste treatment cost is not increased.
Drawings
FIG. 1 is a schematic flow chart of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
example 1
Na with the concentration of 10 percent is prepared2CO3Adding the solution into raffinate, mixing and stirring, and adding the raffinate and Na2CO3The mass ratio of the solution is 3.5: 1. will contain precipitated CaCO3The slurry is filtered and separated to obtain CaCO3Precipitate and salt solution. Mixing CaCO3Adding 10% dilute hydrochloric acid into the precipitate for neutralization to obtain recyclable CaCl2And (3) solution. The salt solution is fed into an adsorption system containing 5 percent of active carbon firstly and then fedThe water enters a reverse osmosis membrane system, high-concentration salt (the salt content is 8.2%) is enriched, and fresh water (the salt content is 0.2%) is discharged. And (4) sending the high-concentration salt into an MVR system to obtain salt crystals with the precipitated concentration of 60%.
Example 2
K with the concentration of 10 percent is prepared2CO3Adding the solution into raffinate, mixing and stirring, and adding the raffinate and Na2CO3The mass ratio of the solution is 2.7: 1. will contain precipitated CaCO3The slurry is filtered and separated to obtain CaCO3Precipitate and salt solution. Mixing CaCO3Adding 10% dilute hydrochloric acid into the precipitate for neutralization to obtain recyclable CaCl2And (3) solution. The salt solution is sent to an adsorption system containing 5% of activated carbon, and then sent to a reverse osmosis membrane system, so that high-concentration salt (the salt content is 6.2%) is enriched and fresh water (the salt content is 0.1%) is discharged. And (4) sending the high-concentration salt into an MVR system to obtain salt crystals with the precipitated concentration of 65%.
Example 3
Na with the concentration of 20 percent is prepared2CO3Adding the solution into raffinate, mixing and stirring, and adding the raffinate and Na2CO3The mass ratio of the solution is 1.8: 1. will contain precipitated CaCO3The slurry is filtered and separated to obtain CaCO3Precipitate and salt solution. Mixing CaCO3Adding 5% dilute hydrochloric acid into the precipitate for neutralization to obtain recyclable CaCl2And (3) solution. The salt solution is sent to an adsorption system containing 8% of activated carbon, and then sent to a reverse osmosis membrane system, so that high-concentration salt (the salt content is 8.2%) is enriched and fresh water (the salt content is 0.2%) is discharged. And (4) sending the high-concentration salt into an MVR system to obtain salt crystals with the precipitated concentration of 60%.
Example 4
NaHCO with preparation concentration of 10%3Adding the solution into raffinate, mixing and stirring, and adding the raffinate and Na2CO3The mass ratio of the solution is 1.6: 1. will contain precipitated CaCO3The slurry is filtered and separated to obtain CaCO3Precipitate and salt solution. Mixing CaCO3Adding 5% dilute hydrochloric acid into the precipitate for neutralization to obtain recyclable CaCl2And (3) solution. The salt solution is fed into an adsorption system containing 5% of amino-crosslinked resin, and then fed into a reverse osmosis membrane system, so that high-concentration salt (the salt content is 7.6%) is enriched, and fresh water (the salt content is 0.2%) is discharged. And sending the high-concentration salt into an MVR system to obtain salt crystals with the precipitated concentration of 70%.
Example 5
Na with the concentration of 10 percent is prepared2CO3Adding the solution into raffinate, mixing and stirring, and adding the raffinate and Na2CO3The mass ratio of the solution is 3.5: 1. will contain precipitated CaCO3The slurry is filtered and separated to obtain CaCO3Precipitate and salt solution. Mixing CaCO3Adding 10% dilute hydrochloric acid into the precipitate for neutralization to obtain recyclable CaCl2And (3) solution. And the salt solution is firstly sent into an adsorption system containing 8% of amino-based cross-linked resin and then sent into a reverse osmosis membrane system, so that high-concentration salt (the salt content is 8.2%) is enriched and fresh water (the salt content is 0.2%) is discharged. And (4) sending the high-concentration salt into an MVR system to obtain salt crystals with the precipitated concentration of 60%.
TABLE 1 summary of the ingredients of the materials
Component name Raffinate Decalcification slurry Precipitate Salt solution
H2O 94.9％ 90.8％ 60.1％ 95.8％
CaCl2 2.9％ - - -
NaCl 2.1％ 4.5％ 0.2％ 4.0％
NMP 0.1％ 0.1％ - 0.1％
CaCO3 - 4.5％ 39.7％ -
Soluble carbonate - 0.1％ - 0.1％
TABLE 2 comparison of adsorption effects of activated carbon
Figure BDA0002271811490000051

Claims (6)

1. Method for treating raffinate in recovery process of para-aramid solvent, wherein the raffinate contains NaCl and CaCl2And a small amount of NMP, characterized in that the treatment method comprises the following steps:
(1) calcium salt precipitation step:
adding a certain amount of soluble carbonate into raffinate to obtain precipitate CaCO3And a salt solution;
(2) sodium salt enrichment and concentration step:
sending the neutralized salt solution into an organic adsorption system, and removing organic impurities; feeding the solution after impurity removal into a system containing a reverse osmosis membrane to obtain high-concentration salt and fresh water;
(3) sodium salt dissolving and recovering step:
and (3) sending the high-concentration salt obtained in the step (2) into a multi-effect evaporation system (MVR) to obtain salt crystals.
2. The method for treating raffinate in the recovery process of para-aramid solvent as claimed in claim 1, wherein, in the step (1), CaCO is obtained3Neutralizing with dilute hydrochloric acid to obtain CaCl2The solution can be recovered as a cosolvent to be continuously used for aramid polymerization.
3. The method of claim 1, wherein the soluble carbonate comprises Na2CO3、NaHCO3、K2CO3、KHCO3Any one or more of them.
4. The method of claim 1, wherein the organic adsorption system comprises a carbon adsorption system or a resin adsorption system.
5. The method for treating raffinate in the recovery process of para-aramid solvent according to claim 1, wherein the content of the high-concentration salt is 5-15%, and the content of the salt in fresh water is less than or equal to 0.2%.
6. The method of claim 1, wherein the concentration of the obtained salt crystals is 60-75%.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111807593A (en) * 2020-07-23 2020-10-23 河南神马尼龙化工有限责任公司 Integrated device and process for treating and utilizing salt-containing organic wastewater in para-aramid solvent workshop section

Citations (6)

* Cited by examiner, † Cited by third party
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US20030228251A1 (en) * 1998-07-16 2003-12-11 Boryta Daniel Alfred Production of lithium compounds directly from lithium containing brines
CN101550233A (en) * 2008-04-03 2009-10-07 中国神马集团有限责任公司 Method for continuously recycling solvent-flux for industrially compounding PPTA
CN102634011A (en) * 2012-04-01 2012-08-15 山东万圣博科技股份有限公司 Poly-p-phenylene terephthamide (PPTA) polymer washing and solvent recovery method
CN104843924A (en) * 2015-05-13 2015-08-19 浙江大洋生物科技集团股份有限公司 Treatment method for saliferous high-concentration organic process waste water during fosfomycin calcium production
CN109761425A (en) * 2019-01-24 2019-05-17 河南神马尼龙化工有限责任公司 The separation and recovery system of NMP in a kind of saline solns
CN110357802A (en) * 2018-03-26 2019-10-22 中国石油化工股份有限公司 Solvent recovery process in a kind of cleaning solution waste liquid producing p-aramid fiber

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030228251A1 (en) * 1998-07-16 2003-12-11 Boryta Daniel Alfred Production of lithium compounds directly from lithium containing brines
CN101550233A (en) * 2008-04-03 2009-10-07 中国神马集团有限责任公司 Method for continuously recycling solvent-flux for industrially compounding PPTA
CN102634011A (en) * 2012-04-01 2012-08-15 山东万圣博科技股份有限公司 Poly-p-phenylene terephthamide (PPTA) polymer washing and solvent recovery method
CN104843924A (en) * 2015-05-13 2015-08-19 浙江大洋生物科技集团股份有限公司 Treatment method for saliferous high-concentration organic process waste water during fosfomycin calcium production
CN110357802A (en) * 2018-03-26 2019-10-22 中国石油化工股份有限公司 Solvent recovery process in a kind of cleaning solution waste liquid producing p-aramid fiber
CN109761425A (en) * 2019-01-24 2019-05-17 河南神马尼龙化工有限责任公司 The separation and recovery system of NMP in a kind of saline solns

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111807593A (en) * 2020-07-23 2020-10-23 河南神马尼龙化工有限责任公司 Integrated device and process for treating and utilizing salt-containing organic wastewater in para-aramid solvent workshop section
CN111807593B (en) * 2020-07-23 2023-07-18 河南神马芳纶技术开发有限公司 Salt-containing organic wastewater treatment and utilization integrated device and process for para-aramid solvent working section

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