CN111072053B - 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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CN111072053B
CN111072053B CN201911107683.XA CN201911107683A CN111072053B CN 111072053 B CN111072053 B CN 111072053B CN 201911107683 A CN201911107683 A CN 201911107683A CN 111072053 B CN111072053 B CN 111072053B
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salt
concentration
raffinate
solution
para
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CN111072053A (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

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Materials Engineering (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

The inventionDiscloses a method for treating raffinate in a para-aramid solvent recovery process, wherein the raffinate contains NaCl and CaCl 2 And 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 CaCO 3 And 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 to obtain salt crystals. The invention realizes effective separation and recycling of sodium salt and calcium salt, and simultaneously reduces production cost and environmental pollution by utilizing the existing adsorption method, membrane concentration and multi-effect evaporation technology.

Description

Treatment method of raffinate in recovery process of para-aramid solvent
Technical Field
The invention relates to the technical field related to wastewater treatment, and particularly relates to a treatment method of raffinate in a para-aramid solvent recovery process.
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 CaCl 2 And 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 salt 2 As a neutralizing agent. But due to Ca (OH) 2 The 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 impurity is inevitably brought into the system. The sodium salt has high solubility and is not easy to separate, and the literature is less concerned with the treatment scheme of the wastewater.
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 is mixed with the neutralized washing liquid, the mixture is further conveyed to an extraction tower for extraction and separation, 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 cannot discharge 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 utilizing the existing adsorption method, membrane concentration and multi-effect evaporation 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 CaCl 2 And 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 CaCO 3 And 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 to obtain salt crystals.
In a preferred embodiment of the invention, CaCO is obtained in step (1) 3 Neutralizing with dilute hydrochloric acid to obtain CaCl 2 The 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 Na 2 CO 3 、NaHCO 3 、K2CO 3 、KHCO 3 Any 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 multi-effect evaporation 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 obtained for reuse in the process of separating salt, so that the water resource consumption is reduced, and the production is further reducedAnd (4) cost. In addition, the invention does not need to treat solid wastes, and the obtained CaCO 3 Neutralizing with dilute hydrochloric acid to obtain CaCl 2 The 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 prepared 2 CO 3 Adding the solution into the raffinate, mixing and stirring, and adding the raffinate and Na 2 CO 3 The mass ratio of the solution is 3.5: 1. will contain precipitated CaCO 3 The slurry is filtered and separated to obtain CaCO 3 Precipitate and salt solution. Mixing CaCO 3 Adding 10% dilute hydrochloric acid into the precipitate for neutralization to obtain recyclable CaCl 2 And (3) solution. The salt solution is fed into an adsorption system containing 5% of activated carbon, and then fed 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 then the high-concentration salt is sent into a multi-effect evaporation system to obtain salt crystals with the precipitated concentration of 60%.
Example 2
K with the concentration of 10 percent is prepared 2 CO 3 Adding the solution into raffinate, mixing and stirring, and adding the raffinate and Na 2 CO 3 The mass ratio of the solution is 2.7: 1. will contain precipitated CaCO 3 The slurry is filtered and separated to obtain CaCO 3 Precipitate and salt solution. Mixing CaCO 3 Adding 10% dilute hydrochloric acid into the precipitate for neutralization to obtain recyclable CaCl 2 And (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 sending the high-concentration salt into a multi-effect evaporation system to obtain salt crystals with the precipitated concentration of 65%.
Example 3
Na with the concentration of 20 percent is prepared 2 CO 3 Adding the solution into raffinate, mixing and stirring, and adding the raffinate and Na 2 CO 3 The mass ratio of the solution is 1.8: 1. will contain precipitated CaCO 3 The slurry is filtered and separated to obtain CaCO 3 Precipitate and salt solution. Mixing CaCO 3 Adding 5% dilute hydrochloric acid into the precipitate for neutralization to obtain recyclable CaCl 2 And (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 then the high-concentration salt is sent into a multi-effect evaporation system to obtain salt crystals with the precipitated concentration of 60%.
Example 4
NaHCO with preparation concentration of 10% 3 Adding the solution into raffinate, mixing and stirring, and adding the raffinate and Na 2 CO 3 The mass ratio of the solution is 1.6: 1. will contain precipitated CaCO 3 The slurry is filtered and separated to obtain CaCO 3 Precipitate and salt solution. Mixing CaCO 3 Adding 5% dilute hydrochloric acid into the precipitate for neutralization to obtain recyclable CaCl 2 And (3) solution. The salt solution is fed into an adsorption system containing 5% of amino cross-linked 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 then the high-concentration salt is sent into a multi-effect evaporation system to obtain salt crystals with 70% of precipitated concentration.
Example 5
Na with the concentration of 10 percent is prepared 2 CO 3 Adding the solution into raffinate, mixing and stirring, and adding the raffinate and Na 2 CO 3 The mass ratio of the solution is 3.5: 1. will contain precipitated CaCO 3 The slurry is filtered and separated to obtain CaCO 3 Precipitate and salt solution. Mixing CaCO 3 Adding 10% dilute hydrochloric acid into the precipitate for neutralization to obtain recyclable CaCl 2 And (3) solution. The salt solution is fed into an adsorption system containing 8% of amino cross-linked resin, and then fed 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 then the high-concentration salt is sent into a multi-effect evaporation system to obtain salt crystals with the precipitated concentration of 60%.
TABLE 1 summary of the ingredients of the materials
Component name Raffinate Decalcifying slurry Precipitate Salt solution
H 2 O 94.9％ 90.8％ 60.1％ 95.8％
CaCl 2 2.9％ - - -
NaCl 2.1％ 4.5％ 0.2％ 4.0％
NMP 0.1％ 0.1％ - 0.1％
CaCO 3 - 4.5％ 39.7％ -
Soluble carbonate - 0.1％ - 0.1％
TABLE 2 comparison of the adsorption effects of activated carbon
Figure GDA0003707767820000051

Claims (3)

1. Method for treating raffinate in para-aramid solvent recovery process, wherein the raffinate contains NaCl and CaCl 2 And 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 CaCO 3 And a neutralized salt solution;
the soluble carbonate salt comprises Na 2 CO 3 、NaHCO 3 、K 2 CO 3 、KHCO 3 Any one or more of;
the obtained CaCO 3 Neutralizing with dilute hydrochloric acid to obtain CaCl 2 The solution is recovered as a cosolvent and is continuously used for aramid polymerization;
(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;
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%;
(3) sodium salt dissolving and recovering steps:
and (3) sending the high-concentration salt obtained in the step (2) into a multi-effect evaporation system to obtain salt crystals.
2. The method of claim 1, wherein the organic adsorption system comprises a carbon adsorption system or/and a resin adsorption system.
3. The method for treating raffinate in the recovery process of para-aramid solvent according to claim 1, wherein the obtained salt crystal concentration is 60-75%.
CN201911107683.XA 2019-11-13 2019-11-13 Method for treating raffinate in recovery process of para-aramid solvent Active CN111072053B (en)

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