Treatment method and treatment device for molecular sieve crystallization mother liquor wastewater

Abstract

The invention provides a treatment method and a treatment device for molecular sieve crystallization mother liquor wastewater. The treatment method provided by the invention comprises the following steps: S1, mixing molecular sieve crystallization mother liquor wastewater containing organic amine salt and quaternary ammonium alkali salt with an alkaline substance under a stirring condition to obtain slurry containing free organic amine and free quaternary ammonium alkali; s2, carrying out evaporation treatment on the slurry obtained in the step S1 to obtain an evaporated matter containing free organic amine and solid slag containing free quaternary ammonium alkali; and S3, the solid residues in the S2 are subjected to pyrolysis treatment in the absence of oxygen and in the presence of water vapor, and a solid pyrolysis product and pyrolysis gas are obtained. According to the method disclosed by the invention, resource utilization of the organic phosphorus amine molecular sieve crystallization mother liquor wastewater can be realized, the zero emission standard is reached, the operation is simple, and the operation is stable.

Description

Technical Field

[0001] The invention relates to the field of environmental protection, and in particular to a method and a device for treating molecular sieve crystallization mother liquor wastewater. Background Art

[0002] In the molecular sieve production process, a large amount of phosphorus, aluminum, silicon and organic templates are used. The crystallization waste liquid contains organic phosphorus amine salts. Due to its complex composition, its organic template exists in the form of organic salts and has good water solubility, which cannot be recovered by conventional distillation, extraction, and precipitation. Wastewater containing organic templates has biological toxicity and needs to be treated as hazardous waste.

[0003] CN105198147A discloses a method for treating organic amine wastewater generated by the production of molecular sieves and their carrier catalysts, which can treat organic amine wastewater with a mass fraction of 0.1% to 5%, and the recovery rate of organic amine is 80% to 95%. However, in actual use, the problem of zero discharge of wastewater and solid waste cannot be solved, and metal salts are added in the solid residue treatment, introducing a new pollution source and the generated waste gas is not treated.

[0004] CN105439262A discloses a pretreatment method for organic amine-containing wastewater, which can treat various organic amine-containing wastewaters, such as wastewater containing organic amines such as fatty amines, alcohol amines, alicyclic amines, aromatic amines and naphthylamines, has a wide range of applications, is simple to operate, has low operating costs, can effectively reduce the concentration of organic amines in wastewater, and has a high organic amine removal rate. However, for organic amine wastewater of a complex system, the organic amine cannot precipitate when this method is actually used.

[0005] CN110639508A discloses an organic amine industrial wastewater wet oxidation catalyst and its application in industrial wastewater treatment, which is used to solve the pollution problem of organic amine industrial wastewater. However, the equipment investment and operation cost of this method are high, and it is difficult to apply to complex wastewater systems.

[0006] In the production of molecular sieves, in addition to the organic template that can be separated and processed step by step, a large amount of silicon, aluminum and phosphorus are also contained. The existing technology does not recycle valuable resources such as silicon, aluminum and phosphorus. Therefore, a comprehensive treatment method that can recycle organic templates and valuable resources such as silicon, aluminum and phosphorus is needed. Summary of the invention

[0007] In view of the above problems of the prior art, the present invention provides a method and device for treating molecular sieve crystallization mother liquor wastewater. The method disclosed in the present invention can realize the resource utilization of organic phosphorus amine molecular sieve crystallization mother liquor wastewater, meet the zero emission standard, and is simple to operate and stable in operation.

[0008] In a first aspect, the present invention provides a method for treating molecular sieve crystallization mother liquor wastewater, which comprises the following steps:

[0009] S1: mixing molecular sieve crystallization mother liquor wastewater containing organic amine salt and quaternary ammonium salt with alkaline substance under stirring to obtain a slurry containing free organic amine and free quaternary ammonium;

[0010] S2: evaporating the slurry in S1 to obtain a distillate containing free organic amine and a solid residue containing free quaternary ammonium base;

[0011] S3: The solid slag in S2 is subjected to pyrolysis treatment in the absence of oxygen and water vapor to obtain solid pyrolysis products and pyrolysis gas.

[0012] In some embodiments, in S1, the alkaline substance is selected from one or more of sodium hydroxide, potassium hydroxide and calcium oxide.

[0013] In some embodiments, in S1, the ratio of the molar amount of the alkaline substance to the total molar amount of the organic amine salt and the quaternary ammonium salt is (0.1-5):1. In some embodiments, the ratio of the molar amount of the alkaline substance to the total molar amount of the organic amine salt and the quaternary ammonium salt is 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.3:1, 2.5:1, 2.7:1, 3.0:1, 3.3:1, 3.5:1, 3.7:1, 4.0:1, 4.3:1, 4.5:1, 4.7:1 or any value therebetween. In some embodiments, the ratio of the molar amount of the alkaline substance to the total molar amount of the organic amine salt and the quaternary ammonium salt is (0.2-2):1.

[0014] The alkaline substance reacts with the quaternary ammonium salt and the organic amine salt to form free quaternary ammonium salt and the organic amine, which can effectively reduce the evaporation separation temperature of the quaternary ammonium salt and the organic amine.

[0015] In some embodiments, during mixing, the pH of the slurry is 9-12, such as 9.3, 9.5, 9.7, 10, 10.3, 10.5, 10.7, 11, 11.3, 11.5, 11.7, or any value therebetween. In some embodiments, the pH of the slurry is 10-12.

[0016] In some embodiments, in S1, the stirring is performed in a toothed disc mixer (also known as a toothed disc mixer).

[0017] In some embodiments, in S1, the stirring speed is 1000 rpm-4000 rpm, for example, 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm or any value therebetween. In some embodiments, in S1, the stirring speed is 2000 rpm-3000 rpm.

[0018] In the toothed disc mixer, the material and the stirring toothed disc are strongly sheared and rubbed, causing the temperature of the molecular sieve crystallization mother liquor wastewater to rise to above 60°C, which can promote the full reaction of the alkali and achieve the replacement of free quaternary ammonium base and organic amine under low alkali dosage. After stirring, the waste liquid forms a colloidal solution without precipitation, which greatly reduces the cost.

[0019] In some embodiments, the mixer can discharge materials continuously at a discharge rate of 100-30000 Kg / hour.

[0020] In some embodiments, in S1, the stirring time is 0.1h-3h, for example, 0.3h, 0.5h, 0.7h, 1.0h, 1.3h, 1.5h, 1.7h, 2.0h, 2.3h, 2.5h, 2.7h, any value therebetween. In some embodiments, in S1, the stirring time is 0.5h-1.5h.

[0021] In some embodiments, in S2, the temperature of the evaporation treatment is higher than the boiling point of the free organic amine and lower than the boiling point of the free quaternary ammonium base. The free quaternary ammonium base with an evaporation temperature higher than the boiling point of water is left in the solid residue after evaporation. The free organic amine and water with an evaporation temperature lower than the boiling point of water are evaporated, and the distillate is separated from the water and the organic amine by a separation device such as a distillation device, wherein the organic amine is reused for the preparation of the molecular sieve.

[0022] In some embodiments, in S2, the temperature of the evaporation treatment is 40°C-100°C, for example, 50°C, 60°C, 70°C, 80°C or 90°C.

[0023] In some embodiments, in S2, the evaporation process is performed under vacuum conditions. In some embodiments, the vacuum degree is 0.3 Kgf / cm 2 Up to 1.0Kgf / cm 2 , for example 0.4Kgf / cm 2 、0.5Kgf / cm 2 、0.6Kgf / cm 2 、0.7Kgf / cm 2 、0.8Kgf / cm 2 or 0.9Kgf / cm 2 .

[0024] In some embodiments, in S2, the evaporation treatment is performed in a vacuum low-temperature evaporation device and / or a vacuum drying belt.

[0025] In some embodiments, the distillate containing free organic amine in S2 is recycled for molecular sieve crystallization.

[0026] In some embodiments, in S3, the temperature of the pyrolysis treatment is 300°C-450°C, for example, 320°C, 340°C, 360°C, 380°C, 400°C or 420°C.

[0027] In some embodiments, the pyrolysis pressure is -0.2 Kgf / cm 2 Up to 1.0Kgf / cm 2 , for example -0.1Kgf / cm 2 、0.1Kgf / cm 2 、0.2Kgf / cm 2 、0.3Kgf / cm 2 、0.4Kgf / cm 2 、0.5Kgf / cm 2 、0.6Kgf / cm 2 、0.7Kgf / cm 2 、0.8Kgf / cm 2 or 0.9Kgf / cm 2 .

[0028] In some embodiments, in S3, the pyrolysis treatment time is 0.5 h-4 h, for example, 1 h, 1.5 h, 2 h, 2.5 h, 3 h or 3.5 h.

[0029] In some embodiments, in S3, per 100g of solid slag, the amount of water vapor is 0.005g / min-0.3g / min, for example, 0.01g / min, 0.015g / min, 0.02g / min, 0.025g / min, 0.02g / min, 0.025g / min, 0.03g / min, 0.035g / min, 0.04g / min, 0.055g / min, 0.05g / min, 0.07g / min, 0.1g / min, 0.13g / min, 0.15g / min, 0.17g / min, 0.2g / min or 0.25g / min. In some embodiments, in S3, the amount of water vapor is 0.01g / min-0.05g / min.

[0030] The pyrolysis treatment is carried out in the presence of water vapor, so that the pyrolysis temperature is reduced by 100-200°C, and the generation of ethylene in the tail gas can be reduced.

[0031] In some embodiments, in S3, the pyrolysis gas includes one or more of water, triethylamine, diethylamine, ethanol, ethylene glycol, ethyl acetate, ethylene and quaternary ammonium hydroxide.

[0032] In some embodiments, in S3, the pyrolysis treatment is performed in a low-temperature steam pyrolysis treatment device.

[0033] In some embodiments, the low-temperature steam pyrolysis treatment equipment is an anaerobic heating equipment, which can be fed intermittently or continuously.

[0034] In some embodiments, the low-temperature steam pyrolysis treatment equipment has a tail gas outlet connected to a water condenser to recover organic matter in the tail gas.

[0035] In some embodiments, the low-temperature steam pyrolysis treatment equipment, wherein the tail gas discharged from the water condenser is ethylene, and the tail gas ethylene is further introduced into a catalytic combustion device and discharged as carbon dioxide after catalytic combustion.

[0036] In some embodiments, in the low-temperature steam pyrolysis treatment equipment, the quaternary ammonium base contained in the water condenser discharge liquid is purified and reused by extraction.

[0037] In some embodiments, the solid waste residue is treated with steam pyrolysis to effectively remove residual quaternary ammonium alkali, and the TOC of the treated solid product is ≤0.5%, and the effective phosphorus content is ≥20%, which complies with the GB / T20412-2021 "Calcium Magnesium Phosphate Fertilizer" standard.

[0038] In some embodiments, the organic amine is selected from methylamine and / or triethylamine, and the quaternary ammonium base has the general formula R 4 The NOH compound is preferably tetramethylammonium hydroxide and / or tetraethylammonium hydroxide.

[0039] In some embodiments, the organic ammonium salt is selected from one or more of methylamine salts, ethylenediamine salts, trimethylamine salts, triethylamine salts, morpholine salts, organic amine phosphate salts, organic amine silicates, and organic amine aluminum silicates.

[0040] In some embodiments, the organic amine phosphoric acid salt is selected from one or more of methylamine phosphate, ethylenediamine phosphate, trimethylamine phosphate, and triethylamine phosphate.

[0041] In some embodiments, the organic amine silicate is selected from one or more of methylamine silicate, ethylenediamine silicate, trimethylamine silicate and triethylamine silicate.

[0042] In some embodiments, the organic amine aluminum silicate is selected from one or more of methylamine aluminum silicate, ethylenediamine aluminum silicate, trimethylamine aluminum silicate, and triethylamine aluminum silicate.

[0043] In some embodiments, the quaternary ammonium salt is selected from one or more compounds of Formula I,

[0044]

[0045] In formula I, R is selected from C1-C6 alkyl, X is selected from halogen anion, HSO 4 - , H 3 PO 4 - , R 1 COO - , H 2 SiO 3 - or AlSi 2 O 6 - , R 1 An alkyl group selected from C1-C6.

[0046] In some embodiments, R is selected from C1-C4 alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl.

[0047] In some embodiments, R 1 Alkyl selected from C1-C4, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl.

[0048] In some embodiments, X is selected from F - , Cl - Br - ,I - , HSO 4 - , H 3 PO 4 - , R 1 COO - , H 2 SiO 3 - or AlSi 2 O 6 - .

[0049] In some embodiments, the quaternary ammonium salt is selected from one or more of tetramethylammonium salt, tetraethylammonium salt, tetrapropylammonium salt, tetrabutylammonium salt, quaternary ammonium phosphate salt, quaternary ammonium silicate salt and quaternary ammonium aluminum silicate salt.

[0050] In some embodiments, the quaternary ammonium phosphate salt is selected from tetramethyl ammonium phosphate, tetraethyl ammonium phosphate, tetrapropyl ammonium phosphate, and tetrabutyl ammonium phosphate.

[0051] In some embodiments, the quaternary ammonium silicate is selected from tetramethylammonium silicate, tetraethylammonium silicate, tetrapropylammonium silicate, and tetrabutylammonium silicate.

[0052] In some embodiments, the quaternary ammonium aluminum silicate is selected from tetramethyl ammonium aluminum silicate, tetraethyl ammonium aluminum silicate, tetrapropyl ammonium aluminum silicate, and tetrabutyl ammonium aluminum silicate.

[0053] In some embodiments, based on the mass of the molecular sieve crystallization mother liquor wastewater, the total mass content of the organic amine salt and the quaternary ammonium salt is 3%-25%, for example, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23% or 24%.

[0054] In some embodiments, the molecular sieve crystallization mother liquor wastewater is selected from wastewater generated during the production process of phosphate aluminum molecular sieve catalysts.

[0055] In some embodiments, the total concentration of organic amine salt and quaternary ammonium salt in the molecular sieve crystallization mother liquor wastewater is 3wt%-25wt%, P 2 O 5 The concentration of Al is 1wt%-35wt%. 2 O 3 The concentration of SiO is 0.1wt%-7wt%, 2 The concentration is 0.1wt%-6wt%.

[0056] In some embodiments, the molecular sieve crystallization mother liquor wastewater P 2 O 5 The concentration of is 2wt%, 3wt%, 4wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt% or 30wt%.

[0057] In some embodiments, the Al in the molecular sieve crystallization mother liquor wastewater is 2 O 3 The concentration is 0.2wt%, 0.5wt%, 0.7wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt% or 6wt%.

[0058] In some embodiments, the SiO in the molecular sieve crystallization mother liquor wastewater is 2 The concentration is 0.2wt%, 0.5wt%, 0.7wt%, 1wt%, 2wt%, 3wt%, 4wt% or 5wt%.

[0059] In some embodiments, the molecular sieve crystallization mother liquor wastewater further includes one or more of quaternary ammonium phosphate, organic amine phosphate, quaternary ammonium phosphate salt, organic amine phosphate salt, quaternary ammonium silicate, organic amine silicate, quaternary ammonium aluminum silicate and organic amine silicon aluminum salt.

[0060] In some embodiments, the method further comprises step S4:

[0061] The pyrolysis gas in step S3 is condensed to obtain a condensate and tail gas. Preferably, the tail gas is catalytically oxidized, and the quaternary ammonium hydroxide in the condensate is purified and reused by extraction.

[0062] In a second aspect, the present invention provides a molecular sieve crystallization mother liquor wastewater treatment device, which includes a mixing device, an evaporation device, a pyrolysis device and a tail gas treatment device.

[0063] The mixing device is used to mix the molecular sieve crystallization mother liquor wastewater with the alkaline substance to obtain a slurry containing free organic amine and free quaternary ammonium base;

[0064] The evaporation device is used for the first evaporation treatment of the slurry to obtain a distillate containing free organic amines and a solid residue containing free quaternary ammonium bases;

[0065] The pyrolysis device is used for pyrolysis treatment of solid slag to obtain solid pyrolysis products and pyrolysis gas;

[0066] The tail gas treatment device is used for treating pyrolysis gas.

[0067] In some embodiments, the mixing device is selected from a toothed disc mixer.

[0068] In some embodiments, the evaporation device is selected from a vacuum low-temperature evaporation device and / or a vacuum drying belt.

[0069] In some embodiments, the pyrolysis device is selected from low-temperature steam pyrolysis processing equipment.

[0070] In some embodiments, the low-temperature steam pyrolysis treatment equipment is an anaerobic heating equipment, which can be fed intermittently or continuously.

[0071] In some embodiments, the low-temperature steam pyrolysis treatment equipment has a tail gas outlet connected to a water condenser to recover organic matter in the tail gas.

[0072] In some embodiments, the low-temperature steam pyrolysis treatment equipment, wherein the tail gas discharged from the water condenser is ethylene, and the tail gas ethylene is further introduced into a catalytic combustion device and discharged as carbon dioxide after catalytic combustion.

[0073] In some embodiments, in the low-temperature steam pyrolysis treatment equipment, the quaternary ammonium base contained in the water condenser discharge liquid is purified and reused by extraction.

[0074] Beneficial technical effects of the present invention:

[0075] (1) The present invention uses cheap alkali as an additive, and makes the alkali fully react by vigorously stirring the grinding mill, thereby reducing the amount of alkali used, and adopts a step-by-step extraction process to improve the recovery rate of the organic template, which is further reused in the production process with the distilled water.

[0076] (2) The solid waste produced by the present invention is pyrolyzed by low-temperature steam, which reduces the decomposition of quaternary ammonium alkali to produce ethylene, thereby reducing the amount of ethylene tail gas to be processed in the factory. The steam pyrolysis also reduces the conversion of phosphate into pyrophosphate or polyphosphate, thereby increasing the effective phosphorus content in the solid residue. After the solid waste is pyrolyzed, it meets the phosphate fertilizer standard.

[0077] (3) The process flow of this method is simple and easy to implement, and the operation is convenient. The entire treatment process is fully closed and safe and environmentally friendly.

[0078] (4) The method of the present invention can significantly reduce the amount of additives used and reduce processing costs. The process can achieve resource recycling and produce a byproduct - phosphate fertilizer, which can generate additional benefits. At the same time, it reduces tail gas emissions and improves quaternary ammonium alkali recovery, and has high industrial practicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 The present invention is a flowchart of treating molecular sieve crystallization mother liquor wastewater according to some embodiments of the present invention. DETAILED DESCRIPTION

[0080] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments and drawings. The specific embodiments described herein are only used to explain the present invention and are not intended to constitute any limitation to the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concepts of the present disclosure. Such structures and technologies are also described in many publications.

[0081] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0082] In some embodiments, the process of treating molecular sieve crystallization mother liquor wastewater of the present invention is as follows: Figure 1As shown, the molecular sieve crystallization mother liquor wastewater is mixed with alkaline substances and then pulped at high speed to obtain a slurry. The slurry is evaporated to evaporate the low-boiling free organic amine and water, and distilled and recovered for molecular sieve crystallization. The evaporated solid residue containing high-boiling free quaternary ammonium alkali is pyrolyzed under water vapor conditions to obtain a solid pyrolysis product (which can be used as a phosphate fertilizer) and pyrolysis gas (tail gas). The pyrolysis gas is then condensed, the non-condensable tail gas is catalytically oxidized, and the quaternary ammonium alkali contained in the condensate is purified and reused by extraction.

[0083] The present invention will be described in detail below through examples.

[0084] Unless otherwise specified, all operations in the Examples and Comparative Examples were carried out at room temperature.

[0085] The reagents used in the examples are all commercially available.

[0086] The available phosphorus content in the sample was determined by the available phosphorus detection method in the national standard for calcium magnesium phosphate fertilizer (GB20412-2021).

[0087] X-ray fluorescence spectrometer was used to detect the elemental composition of the samples.

[0088] The 6890 gas chromatograph GC-TCD and GC-FID were used to quantitatively analyze the recovered organic amines and the composition of the pyrolysis tail gas.

[0089] The total carbon (TC) and inorganic carbon (IC) in solid samples were analyzed using Shimadzu total organic carbon analyzers TOC-L and SSM-5000A.

[0090] ICS-600 ion chromatography was used to analyze organic amines and quaternary ammonium bases.

[0091] Organic amine recovery rate = recovered organic amine in the pretreatment process / total amount of organic amine in the initial wastewater × 100%.

[0092] Total organic carbon (TOC) = total carbon (TC) - inorganic carbon (IC).

[0093] The organic phosphorus amine molecular sieve crystallization mother liquor wastewater used in the examples and comparative examples is SAPO molecular sieve production wastewater. The organic amine salt is diethylamine phosphate with a content of 0.7 mol / L (119.7 g / L), the quaternary ammonium salt is tetrabutylammonium phosphate with a content of 0.3 mol / L (101.8 g / L), the phosphorus pentoxide content is 17 g / L, the aluminum oxide content is 4 g / L, and the silicon oxide content is 5 g / L.

[0094] Example 1

[0095] Step 1) Pour 1000 mL of wastewater into a container, add 0.5 mol CaO, and beat with a toothed disc mixer for 0.5 hour at a stirring speed of 3000 rpm to obtain a slurry with a pH value of 11.

[0096] Step 2) Pour the slurry into a rotary evaporator for evaporation to obtain a condensate containing water and ethylamine and a solid residue. The evaporation temperature is set at 95°C and the vacuum degree is 0.8 Kgf / cm 2 The recovery rate of ethylamine is 99.8%. The condensate is distilled to ethylamine purity of 99.3%, and the remaining water is reused for production.

[0097] Step 3) Take 100g of the solid residue after evaporation, the water content of the solid residue is 5%, and put it into a sealed heating tank for pyrolysis treatment. The heating tank is controlled at 400°C, and water vapor is introduced at 0.015g / min. The pyrolysis device is kept at a constant temperature for 2 hours.

[0098] The exhaust pipe on the top of the heating tank is connected to a water-cooled condenser tank, which is used to condense the pyrolysis gas after pyrolysis treatment to obtain condensed tail gas. The tail gas discharged from the condenser tank is connected to an air bag for analysis. The total weight of the tail gas collected by the air bag is 0.65g, which is ethylene with a purity of 99%. The ethylene is passed into the catalytic combustion equipment and discharged as carbon dioxide after catalytic combustion. The liquid collected in the condenser tank contains 70% tetrabutylammonium hydroxide, which can be purified by extraction and reused.

[0099] The solid product obtained after steam pyrolysis in the heating tank has a residual organic matter TOC of 0.31 mg / g, a pH value of 7, and an effective phosphorus content of 33% in the pyrolysis solid product, which meets the standards for phosphate fertilizer.

[0100] Example 2

[0101] Step 1) Pour 1000 mL of wastewater into a container, add 1 mol of NaOH, and beat with a toothed disc stirrer for 0.5 hour at a stirring speed of 3000 rpm to obtain a slurry with a pH value of 11.

[0102] Step 2) Pour the slurry into a rotary evaporator for evaporation to obtain a condensate containing water and ethylamine and a solid residue. The evaporation temperature is set at 95°C and the vacuum degree is 0.8 Kgf / cm 2 The recovery rate of ethylamine is 99.8%. The condensate is distilled and purified to obtain 99.4% ethylamine, and the remaining water is recycled for production.

[0103] Step 3) Take 100g of the solid residue after evaporation, the water content of the solid residue is 5%, and put it into a sealed heating tank for pyrolysis treatment. The heating tank is controlled at 400°C, and water vapor is introduced at 0.015g / min. The pyrolysis device is kept at a constant temperature for 2 hours.

[0104] The exhaust pipe at the top of the heating tank is connected to a water-cooled condensation tank, which is used to condense the pyrolysis gas after pyrolysis treatment to obtain condensed tail gas. The tail gas discharged from the condensation tank is connected to a gas bag for analysis. The total weight of the tail gas collected by the gas bag is 0.7 g, which is ethylene with a purity of 99%. The ethylene is introduced into a catalytic combustion device and discharged as carbon dioxide after catalytic combustion. The collected liquid in the condensation tank contains 70% tetrabutylammonium hydroxide and can be recycled by extraction and purification.

[0105] Steam pyrolysis solid products are obtained in the heating tank. The residual organic matter TOC is 0.3 mg / g, the pH value is 7, and the available phosphorus in the pyrolysis solid products is 32%, meeting the phosphate fertilizer standard.

[0106] Example 3

[0107] The difference from Example 1 is only that: 0.3 mol of CaO is added in step 1). The slurry is beaten by a toothed disc mixer for 0.5 hours at a stirring speed of 3000 revolutions per minute to obtain a slurry with a pH value of 10.

[0108] In step 2), the recovery rate of ethylamine is 74%.

[0109] In step 3), the total weight of the tail gas collected by the gas bag is 5.2 g, which is ethylene with a purity of 92%. The collected liquid in the condensation tank contains 61% tetrabutylammonium hydroxide. The residual TOC in the steam pyrolysis product is 1.7 mg / g, the pH value is 6.8, and the available phosphorus in the pyrolysis product is 25%.

[0110] Example 4

[0111] The difference from Example 1 is only that: 1 mol of CaO is added in step 1). The slurry is beaten by a toothed disc mixer for 0.5 hours at a stirring speed of 3000 revolutions per minute to obtain a slurry with a pH value of 12.

[0112] In step 2), the recovery rate of ethylamine is 99%.

[0113] In step 3), the total weight of the tail gas collected by the gas bag is 1.7 g, which is ethylene with a purity of 98%. The collected liquid in the condensation tank contains 67% tetrabutylammonium hydroxide. The residual TOC in the steam pyrolysis product is 0.4 mg / g, the pH value is 11.7, and the available phosphorus in the pyrolysis product is 31%.

[0114] Example 5

[0115] The difference from Example 1 is only that: 1.5 mol of CaO is added in step 1). The slurry is beaten by a toothed disc mixer for 0.5 hours at a stirring speed of 3000 revolutions per minute to obtain a slurry with a pH value of 12.

[0116] In step 2), the recovery rate of ethylamine is 99%.

[0117] In step 3), the total weight of tail gas collected by the air bag is 2.1g, which is ethylene with a purity of 97%. The liquid collected by the condenser contains 65% tetrabutylammonium hydroxide. The residual TOC in the steam pyrolysis product is 0.4mg / g, the pH value is 12, and the effective phosphorus in the pyrolysis product is 29%.

[0118] Example 6

[0119] The only difference from Example 1 is that 0.5 mol of CaO is added in step 1). A common blade stirrer (DEWENT model SF-210) is used for stirring for 0.5 hours at a stirring speed of 3000 rpm to obtain a slurry with a pH value of 8.9.

[0120] In step 2), the recovery rate of ethylamine is 34.3%.

[0121] In step 3), the total weight of tail gas collected by the air bag is 0.43g, which is ethylene with a purity of 81.3%. The liquid collected in the condenser contains 49.6% tetrabutylammonium hydroxide. The residual TOC in the steam pyrolysis product is 2.4mg / g, the pH value is 6.7, and the effective phosphorus in the pyrolysis product is 22%.

[0122] Example 7

[0123] The only difference from Example 1 is that in step 3), 0.005 g / min of water vapor is introduced.

[0124] The total weight of tail gas collected by the air bag is 0.4g, which is ethylene with a purity of 99%. The liquid collected by the condenser contains 58% tetrabutylammonium hydroxide. The residual TOC in the water vapor pyrolysis product is 0.47%, the pH value is 7, and the effective phosphorus in the pyrolysis product is 28%.

[0125] Example 8

[0126] The only difference from Example 1 is that in step 3), 0.025 g / min of water vapor is introduced.

[0127] The total weight of tail gas collected by the air bag is 0.66g, which is ethylene with a purity of 99%. The liquid collected by the condenser contains 69% tetrabutylammonium hydroxide. The residual TOC in the water vapor pyrolysis product is 0.30%, the pH value is 7, and the effective phosphorus in the pyrolysis product is 34%.

[0128] Example 9

[0129] The only difference from Example 1 is that in step 3), 0.1 g / min of water vapor is introduced.

[0130] The total weight of tail gas collected by the air bag is 0.66g, which is ethylene with a purity of 99%. The liquid collected by the condenser contains 64% tetrabutylammonium hydroxide. The residual TOC in the water vapor pyrolysis product is 0.30%, the pH value is 7, and the effective phosphorus in the pyrolysis product is 34%.

[0131] Example 10

[0132] Step 1) Pour 1000 mL of wastewater into a container, add 4.5 mol CaO, and stir with a common blade stirrer (DEWENT model SF-210) for 0.5 hour at a stirring speed of 60 rpm to obtain a slurry with a pH value of 11.5.

[0133] Step 2) Pour the slurry into a rotary evaporator for evaporation to obtain a condensate containing water and ethylamine and a solid residue. The evaporation temperature is set at 95°C and the vacuum degree is 0.8 Kgf / cm 2 The recovery rate of ethylamine is 90%, and the purity of ethylamine in the condensate is 99.4% after distillation, and the remaining water is reused for production.

[0134] Step 3) Take 100g of solid residue from evaporation, the moisture content of which is 5%, and put it into a sealed heating tank for pyrolysis treatment. The temperature of the heating tank is controlled at 400°C, and water vapor is introduced at 0.015g / min. The pyrolysis device is kept at a constant temperature for 2 hours.

[0135] The exhaust pipe on the top of the heating tank is connected to a water-cooled condenser tank, which is used to condense the pyrolysis gas after pyrolysis treatment to obtain condensed tail gas. The tail gas discharged from the condenser tank is connected to an air bag for analysis. The total weight of the tail gas collected by the air bag is 2.3g, which is ethylene with a purity of 99%. The ethylene is passed into the catalytic combustion equipment and discharged as carbon dioxide after catalytic combustion, and the ethylene processing capacity is greatly increased. The liquid collected in the condenser tank is 60% tetrabutylammonium hydroxide, which can be purified and reused by extraction.

[0136] A steam pyrolysis solid product was obtained in the heating tank, wherein the residual organic matter TOC was 0.7 mg / g, the pH value was 11.5, and the effective phosphorus of the pyrolysis product was 22%.

[0137] Comparative Example 1

[0138] Step 1) Pour 1000 mL of wastewater into a rotary evaporator for evaporation. The evaporation temperature is set at 95°C and the vacuum degree is 0.8 Kgf / cm 2 The condensed gas recovery liquid is water, and no organic amine is evaporated. Because the organic amine and quaternary ammonium base are not replaced, they remain in the solid slag in the form of organic salts.

[0139] Step 2) 100 g of the solid residue after evaporation, with a water content of 15%, was placed in a sealed heating tank for pyrolysis treatment. The temperature of the heating tank was controlled at 400° C., and the low-temperature pyrolysis device was kept at a constant temperature for 2 hours.

[0140] The exhaust pipe on the top of the heating tank is connected to a water-cooled condenser tank, which is used to condense the pyrolysis gas after pyrolysis treatment to obtain condensed tail gas. The total weight of the tail gas collected by the air bag is 12.9g, which is ethylene with a purity of 99%. The ethylene is passed into the catalytic combustion equipment, and the processing capacity is greatly increased. The liquid collected in the condenser tank contains water, triethylamine, diethylamine, ethanol, ethylene glycol and ethyl acetate.

[0141] The pyrolysis solid product was obtained in the heating tank, wherein the residual TOC of organic matter was 390 mg / g, the pH value was 4.5, and the effective phosphorus of the pyrolysis solid product was 7.3%, which did not meet the phosphate fertilizer standard.

[0142] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for treating molecular sieve crystallization mother liquor wastewater, wherein The following steps are involved: S1: mixing molecular sieve crystallization mother liquor wastewater containing organic amine salt and quaternary ammonium salt with alkaline substance under stirring to obtain a slurry containing free organic amine and free quaternary ammonium; S2: evaporating the slurry in S1 to obtain a distillate containing free organic amine and a solid residue containing free quaternary ammonium base; S3: The solid slag in S2 is subjected to pyrolysis treatment in the absence of oxygen and water vapor to obtain solid pyrolysis products and pyrolysis gas.

2. The processing method according to claim 1, It is characterized in that In S1, the alkaline substance is selected from one or more of sodium hydroxide, potassium hydroxide and calcium oxide; The ratio of the molar amount of the alkaline substance to the total molar amount of the organic amine salt and the quaternary ammonium salt is (0.1-5):1, preferably (0.2-2):

1.

3. The processing method according to claim 1 or 2, It is characterized in that In S1, the stirring is carried out in a toothed disc mixer; and / or The stirring speed is 1000 rpm-4000 rpm, preferably 2000 rpm-3000 rpm; and / or The stirring time is 0.1h-3h, preferably 0.5h-1.5h; and / or The pH of the slurry is 9-12, preferably 10-12.

4. The processing method according to any one of claims 1 to 3, It is characterized in that In S2, the temperature of the evaporation treatment is higher than the boiling point of the free organic amine and lower than the boiling point of the free quaternary ammonium base; Preferably, the temperature of the evaporation treatment is 40°C-100°C; Preferably, the evaporation treatment is carried out under vacuum conditions, and preferably the vacuum degree is 0.3 Kgf / cm 2 Up to 1.0Kgf / cm 2 .

5. The processing method according to any one of claims 1 to 4, It is characterized in that In S3, the temperature of the pyrolysis treatment is 300°C-450°C, and the pressure of the pyrolysis treatment is -0.2Kgf / cm 2 Up to 1.0Kgf / cm 2 , the pyrolysis treatment time is 0.5h-4h; and / or For every 100 g of solid slag, the amount of water vapor used is 0.005 g / min-0.3 g / min, preferably 0.01 g / min-0.05 g / min.

6. The treatment method according to any one of claims 1 to 5, It is characterized in that In S3, the pyrolysis gas includes one or more of water, triethylamine, diethylamine, ethanol, ethylene glycol, ethyl acetate, ethylene and quaternary ammonium hydroxide.

7. The treatment method according to any one of claims 1 to 6, It is characterized in that The organic ammonium salt is selected from one or more of methylamine salt, ethylenediamine salt, trimethylamine salt, triethylamine salt, morpholine salt, organic amine phosphate salt, organic amine silicate and organic amine aluminum silicate; and / or The quaternary ammonium salt is selected from one or more compounds shown in formula I, In formula I, R is selected from C1-C6 alkyl, X is selected from halogen anion, HSO 4 - , H 3 PO 4 - , R 1 COO - , H 2 SiO 3 - or AlSi 2 O 6 - , R 1 An alkyl group selected from C1-C6; Preferably, the quaternary ammonium alkali salt is selected from one or more of tetramethylammonium salt, tetraethylammonium salt, tetrapropylammonium salt, tetrabutylammonium salt, quaternary ammonium phosphate salt, quaternary ammonium silicate salt and quaternary ammonium aluminum silicate salt; and / or Based on the mass of the molecular sieve crystallization mother liquor wastewater, the total mass content of the organic amine salt and the quaternary ammonium salt is 3%-25%.

8. The treatment method according to any one of claims 1 to 7, It is characterized in that The molecular sieve crystallization mother liquor wastewater is selected from the wastewater generated in the production process of phosphorus aluminum molecular sieve catalyst, Preferably, the total concentration of organic amine salt and quaternary ammonium salt in the molecular sieve crystallization mother liquor wastewater is 3wt%-25wt%, P 2 O 5 The concentration of Al is 1wt%-35wt%, 2 O 3 The concentration of SiO is 0.1wt%-7wt%, 2 The concentration is 0.1wt%-6wt%.

9. The treatment method according to any one of claims 1 to 8, It is characterized in that The method further comprises step S4: The pyrolysis gas in step S3 is condensed to obtain a condensate and tail gas. Preferably, the tail gas is catalytically oxidized, and the quaternary ammonium hydroxide in the condensate is purified and reused by extraction.

10. A molecular sieve crystallization mother liquor wastewater treatment device, comprising a mixing device, an evaporation device, a pyrolysis device and a tail gas treatment device, The mixing device is used to mix the molecular sieve crystallization mother liquor wastewater with the alkaline substance to obtain a slurry containing free organic amine and free quaternary ammonium base. Preferably, the mixing device is selected from a toothed disc mixer; The evaporation device is used for evaporation treatment of the slurry to obtain a distillate containing free organic amines and a solid residue containing free quaternary ammonium bases. Preferably, the evaporation device is selected from a vacuum low-temperature evaporation device and / or a vacuum drying belt; The pyrolysis device is used for pyrolysis treatment of solid slag to obtain solid pyrolysis products and pyrolysis gas; The tail gas treatment device is used for treating pyrolysis gas.

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