CN112279273A - Treatment method for removing COD (chemical oxygen demand) of industrial byproduct salt - Google Patents
Treatment method for removing COD (chemical oxygen demand) of industrial byproduct salt Download PDFInfo
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- CN112279273A CN112279273A CN201910670504.7A CN201910670504A CN112279273A CN 112279273 A CN112279273 A CN 112279273A CN 201910670504 A CN201910670504 A CN 201910670504A CN 112279273 A CN112279273 A CN 112279273A
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- 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
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- 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
- C01D3/14—Purification
- C01D3/18—Purification with selective solvents
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
- C01D5/16—Purification
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- 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
- C02F1/26—Treatment of water, waste water, or sewage by extraction
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Abstract
The invention provides a treatment method for removing industrial byproduct salt COD, which comprises the following steps: (1) adding a dissolving-out agent into the industrial byproduct salt solution, and mixing to obtain prefabricated slurry; (2) and (2) performing solid-liquid separation on the prefabricated slurry obtained in the step (1), and drying a solid phase obtained by the solid-liquid separation to obtain a refined salt product. The treatment method can treat industrial byproduct salt with different sources and types, and salt is separated out through the dissolution crystallization process of a dissolution agent, so that the effective separation of the salt and water-soluble and fat-soluble impurities is realized, and a high-purity refined salt product and a recyclable liquid-phase product are obtained; in addition, the treatment process has mild conditions, low energy consumption and simple process. Therefore, the treatment method for removing the industrial byproduct salt COD provided by the invention has strong universality, high COD removal rate and high yield of refined salt, does not generate a large amount of industrial three wastes, and can realize the maximization of the resources of the industrial byproduct salt in an efficient and environment-friendly way.
Description
Technical Field
The invention belongs to the technical field of byproduct salt treatment, and particularly relates to a treatment method for removing industrial byproduct salt COD.
Background
A large amount of high-salt-content wastewater is generated in the production processes of chemical products such as coal chemical industry, chemical raw materials, drug synthesis, pesticides, dyes, special chemicals, fine chemicals and the like, and is taken as a key industry for special environmental protection treatment. According to incomplete statistics, the total amount of byproduct salt in the chemical industry of China is up to more than 500 million tons every year. The industrial byproduct salt is usually a mixture containing one or more inorganic salts such as sodium chloride, sodium sulfate, potassium chloride, sodium sulfite and the like, and is entrained with toxic and harmful substances such as heavy metals, organic matters and the like, and the Chemical Oxygen Demand (COD) is high, often has strong pungent odor, and the environmental pollution is serious. Although industrial byproduct salt has not been listed in the national hazardous waste list (2016), the industry has classified the industrial byproduct salt into hazardous waste management category, potential safety hazards exist in landfill, meanwhile, the cost of harmless treatment is high, and most disposal units are reluctant to accept the hazardous waste management category. Due to the lack of effective utilization, many manufacturing enterprises can only stock or transfer high prices to third parties. In developed areas of chemical industry such as Jiangsu, Zhejiang and Shandong, the amount of miscellaneous salt accumulated in part of chemical parks, production enterprises and environmental protection companies is large, and the resource treatment of industrial byproduct salt is a serious problem.
The key point of the resource treatment of the industrial byproduct salt is to remove heavy metal and COD in the industrial byproduct salt. The common treatment methods for removing the industrial byproduct salt COD at present comprise a salt washing method, a burning method, a high-temperature pyrolysis method, a landfill method and the like. CN105347363A discloses a process for treating byproduct industrial salt by a water washing adsorption method, which comprises the following steps: (1) dissolving the byproduct industrial salt in water, primarily filtering the solution by a sand filter, and then adjusting the pH value to 1-5; (2) filtering through an activated carbon filter, adsorbing the filtrate through macroporous resin, removing organic matters and organic salts in the wastewater, and reducing the COD of the wastewater; (3) filtering with nanofiltration membrane, adjusting pH to neutral, evaporating, crystallizing, centrifuging to obtain solid salt, and recrystallizing to obtain recrystallized solid; the process has simple route and convenient operation, and can effectively refine and treat the byproduct industrial salt. CN105293531A discloses a refining treatment method of byproduct industrial salt, which comprises the following steps: mixing the byproduct industrial salt with water, heating, adding active carbon, and stirring; filtering, and spray drying the filtrate to obtain solid salt; then crushing the solid salt, putting the crushed solid salt into a high-temperature kiln, and performing medium-temperature firing under an aerobic condition to carbonize organic impurities in the waste salt to obtain a gray solid; further dissolving, removing impurities and dehydrating the solid to obtain pure white salt crystals; the treatment method can effectively remove organic matters in the byproduct industrial salt, reduce waste and improve environmental protection. CN109943364A discloses a high-salt high-COD chemical hazardous waste treatment and recycling method, in the method, high-salt high-COD chemical hazardous waste is mixed with water for pretreatment, and then the pretreated material slurry is subjected to pyrohydrolysis treatment to generate high-concentration brine and mixed gas; then salt substances in the high-concentration brine are recovered by adopting an evaporation technology, and the mixed gas is converted into methane by adopting a catalytic reforming technology, so that clean energy is obtained; the method has the advantages of high organic matter removal rate, high salt recovery rate, no toxic by-products and the like, and realizes efficient treatment and recycling of high-salt high-COD chemical hazardous wastes.
In the prior art, however, part of water-soluble impurities in the byproduct salt can be removed by a salt washing method, but the toxic and harmful components are difficult to be completely removed and converted into refined salt products; the incineration method removes COD of the byproduct salt by direct incineration or mixed incineration with other solid wastes, but the method has high energy consumption, and the incineration of the high-chlorine byproduct salt can generate a large amount of dioxin to cause secondary pollution, and the byproduct salt has strong corrosivity and can influence the operation stability, the treatment capacity and the service life of incineration equipment; the high-temperature pyrolysis method decomposes organic impurities in the byproduct salt into gas at high temperature to remove COD in the byproduct salt, but the problem of ring caking of the byproduct salt in thermal equipment at high temperature is difficult to solve, and the treatment cost is high; the landfill method is to carry out landfill after harmless curing treatment of the byproduct salt, which not only has high cost (5000-8000 yuan/ton), but also causes waste of salt resources.
Therefore, the development of a treatment method for removing the industrial byproduct salt COD, which is efficient, easy to operate and low in cost, is the focus of research in the field.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a treatment method for removing industrial byproduct salt COD, wherein in the treatment method, COD is removed by carrying out elution crystallization on salts in an industrial byproduct salt solution through a elutriation agent to obtain a refined salt product, incineration and other heat treatment processes are avoided, technical support is provided for resource regeneration of the industrial byproduct salt, and the treatment method has the advantages of simple flow, mild conditions, low energy consumption and the like.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a treatment method for removing industrial byproduct salt COD, which comprises the following steps:
(1) adding a dissolving-out agent into the industrial byproduct salt solution, and mixing to obtain prefabricated slurry;
(2) and (2) performing solid-liquid separation on the prefabricated slurry obtained in the step (1), and drying a solid phase obtained by the solid-liquid separation to obtain a refined salt product.
The treatment method for removing the COD of the industrial byproduct salt is based on a dissolving-out crystallization process of a dissolving-out agent on salts in an industrial byproduct salt solution, so that the salts are crystallized and separated out, the effective separation of the salts and organic matters is realized, the COD is removed, and a refined salt product and a recyclable liquid-phase product are obtained, wherein the COD of the refined salt product is lower than 1700mg/kg, even can reach 220mg/kg, the COD removal rate is 92-97%, and the yield of the refined salt product can reach 90-94%; the method has universality and can realize the removal and refining of COD in the byproduct salt obtained by any process in the chemical field. Different from the heat treatment processes such as incineration, high-temperature pyrolysis and the like in the prior art, the removal method can be realized at room temperature, does not need precise and complicated instruments and equipment, has the advantages of low energy consumption, low cost and mild conditions, does not generate industrial three wastes in the treatment process, and is a real environment-friendly removal process.
In the treatment method, the elution crystallization technology is creatively applied to the purification of the industrial byproduct salt, and the introduction of the elution agent leads the salt in the industrial byproduct salt solution to generate supersaturation due to the solubility difference and further crystallize and precipitate. Different from the prior art that the salt washing method can only remove water-soluble impurities, the treatment method can simultaneously separate fat-soluble and water-soluble impurities in the byproduct salt, and realize high-quality refining of salt products. The selection of the elutriation agent needs to be considered from the following two aspects, one is that the elutriation agent and a solvent in an industrial byproduct salt solution can be mutually soluble in any proportion, the elutriation agent has universal solubility on organic impurities in the industrial byproduct salt, and the salt has extremely low solubility and is almost insoluble in the elutriation agent, so that the elutriation agent is mutually soluble with the solvent after being added into the industrial byproduct salt solution, the positive solvent amount of the dissolved salt is reduced, the salt is supersaturated and crystallized and precipitated, and meanwhile, the organic matters and the water-soluble impurities in the industrial byproduct salt are both stored in a liquid phase, and the removal of COD and the refining of the salt are realized; and secondly, the elutriation agent is easy to recover after the elutriation crystallization process is completed, namely, a liquid phase obtained after solid-liquid separation in the step (2) can be directly recycled as a solvent of the elutriation agent or an industrial byproduct salt solution, and can also be purified by an easy-to-operate separation method, wherein the purification method comprises rectification, distillation, flash evaporation, extraction, evaporation, drying, absorption and the like.
Preferably, the solvent of the industrial byproduct salt solution in the step (1) is water or an aqueous solution of an organic solvent.
Preferably, the organic solvent is selected from any one of methanol, ethanol, n-propanol, isopropanol or acetone or a combination of at least two thereof.
Preferably, the volume percentage of the organic solvent in the aqueous solution of the organic solvent is 0.5-50%, for example, 0.7%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 49%, and the specific values therebetween are not exhaustive, and for brevity and conciseness, the invention does not include the specific values included in the range.
Preferably, the industrial byproduct salt solution in the step (1) is a saturated aqueous solution of the industrial byproduct salt.
As a preferred technical scheme of the invention, when the industrial byproduct salt solution in the step (1) is a saturated aqueous solution of the industrial byproduct salt, the elution crystallization efficiency by adding the elution agent is high, the yield and the purity of the obtained refined salt product are high, and the COD removal is more complete.
Preferably, the industrial byproduct salt in step (1) includes an industrial chloride byproduct salt, an industrial byproduct sulfate, or an industrial byproduct sulfite.
Preferably, the COD content of the industrial byproduct salt in the step (1) is 100-100000 mg/kg, such as 150mg/kg, 200mg/kg, 300mg/kg, 500mg/kg, 800mg/kg, 1000mg/kg, 1500mg/kg, 2000mg/kg, 3000mg/kg, 5000mg/kg, 8000mg/kg, 10000mg/kg, 15000mg/kg, 20000mg/kg, 30000mg/kg, 40000mg/kg, 50000mg/kg, 60000mg/kg, 70000mg/kg, 80000mg/kg or 90000mg/kg, and the specific points therebetween are limited to the space and the specific points included in the range are not listed again in the present invention for the sake of brevity.
Preferably, the industrial chloride byproduct salt is a sodium chloride byproduct salt.
Preferably, the industrial by-product sulfate is a sodium sulfate by-product salt.
Preferably, the elution solvent in the step (1) is an organic solvent which is miscible with water.
Preferably, the water-miscible organic solvent is a water-miscible ketone solvent and/or a water-miscible alcohol solvent.
Preferably, the elution agent in step (1) is selected from any one of methanol, ethanol, n-propanol, isopropanol or acetone or a combination of at least two of the above.
Preferably, the boiling point of the elution reagent in step (1) is not higher than 110 ℃, for example, the boiling point of the elution reagent may be 109 ℃, 105 ℃, 100 ℃, 95 ℃, 90 ℃, 85 ℃, 80 ℃, 75 ℃, 70 ℃, 65 ℃ or 60 ℃, etc.
The term "the boiling point of the elution solvent is not higher than 110 ℃" means that the boiling point of the elution solvent is not higher than 110 ℃ when the elution solvent is a single component, and the upper limit of the boiling point range of the elution solvent is not higher than 110 ℃ when the elution solvent is a mixture of at least two components.
Preferably, the volume ratio of the industrial byproduct salt solution to the elution reagent in step (1) is 1 (0.1-10), for example, 1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1, 1:1.3, 1:1.5, 1:1.7, 1:2, 1:2.2, 1:2.5, 1:2.8, 1:3, 1:3.3, 1:3.5, 1:3.8, 1:4, 1:4.3, 1:4.5, 1:4.8, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9 or 1:9.5, and the like, and further preferably 1 (0.2-5).
As a preferable technical scheme, the volume ratio of the industrial byproduct salt solution and the elution agent in the treatment method of the invention is within the above-defined range, and if the dosage of the elution agent is lower than the range defined by the invention, the crystallization of the salt is incomplete, and the yield of the refined salt product is low; if the amount of the elution reagent is more than the above-defined range, resources are wasted due to an excess amount.
Preferably, the rate of adding the elution agent in the step (1) is 0.5-10 mL/min, for example, 0.6mL/min, 0.8mL/min, 1mL/min, 1.3mL/min, 1.5mL/min, 1.8mL/min, 2mL/min, 2.3mL/min, 2.5mL/min, 2.8mL/min, 3mL/min, 3.3mL/min, 3.5mL/min, 3.8mL/min, 4mL/min, 4.3mL/min, 4.5mL/min, 4.8mL/min, 5mL/min, 5.5mL/min, 6mL/min, 6.5mL/min, 7mL/min, 7.5mL/min, 8mL/min, 8.5mL/min, 9mL/min, or 9.5mL/min, and the specific values between the foregoing, are not intended to be exhaustive or to limit the invention to the precise values encompassed within the scope, for reasons of brevity and clarity.
As a preferred technical scheme, when the addition rate of the elutriation agent in the treatment method is in the limited range, the nucleation and growth rate of salt crystallization are proper, the purity of the obtained refined salt product is high, and COD and water-soluble impurities are completely removed. If the addition rate of the elution agent is lower than the range limited by the invention, the crystal nucleus of the elution crystal has slow growth speed, overlong treatment time and low efficiency, the time cost of the treatment process is increased, and the industrialized application is not facilitated; if the addition rate of the elutriation agent is greater than the limited range, the supersaturation level of the byproduct salt at the addition point of the elutriation agent is increased sharply, a large number of primary salt crystal nuclei are generated and aggregates are formed easily in a moment, and the formation of the crystal and the aggregate which are rapidly nucleated and grow under the high degree of over-saturation can occlude a large amount of mother liquor (namely industrial byproduct salt solution), so that the purity and the quality of the salt product are influenced, and the COD removal rate is reduced.
Preferably, the temperature of the mixing in the step (1) is 10 to 100 ℃, for example, 12 ℃, 14 ℃, 16 ℃, 18 ℃, 20 ℃, 21 ℃, 23 ℃, 25 ℃, 27 ℃, 29 ℃, 30 ℃, 33 ℃, 35 ℃, 38 ℃, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 90 ℃ or 95 ℃, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive list of the specific values included in the range, and further preferably room temperature.
Preferably, the mixing time in step (1) is 0.5-12 h, such as 0.6h, 0.8h, 1h, 1.3h, 1.5h, 1.7h, 2h, 2.3h, 2.5h, 2.7h, 3h, 3.3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h or 11.5h, and the specific values therebetween are not exhaustive, and for simplicity, the invention does not list the specific values included in the range, and further preferably 0.5-3 h.
Preferably, the mixing time in the treatment method of the present invention is within the above-defined range, so that the salt is crystallized as completely as possible after the addition of the elution reagent, thereby ensuring the yield of the purified salt product. If the mixing time is less than 0.5h, the dissolution crystallization is incomplete, and the yield of the refined salt product is reduced; if the mixing time is too long, the time cost of the treatment process is increased, which is not favorable for industrial application.
Preferably, the mixing of step (1) is carried out under stirring conditions.
Preferably, the solid-liquid separation method in the step (2) comprises cyclone, sedimentation, filtration or centrifugation.
Preferably, the drying method in step (2) comprises natural air drying, forced air drying, freeze drying, spray drying or flash drying.
Preferably, the processing method comprises the following steps:
(1) adding a solvent-out agent into the industrial byproduct salt solution at the rate of 0.5-10 mL/min, and stirring and mixing at 10-100 ℃ for 0.5-12 h to obtain a prefabricated slurry; the volume ratio of the saturated aqueous solution of the industrial byproduct salt to the elution agent is 1 (0.1-10);
(2) and (2) performing solid-liquid separation on the prefabricated slurry obtained in the step (1), and drying a solid phase obtained by the solid-liquid separation to obtain a refined salt product.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the treatment method for removing the industrial byproduct salt COD, the salt is separated out in the process of elution and crystallization of the salt in the industrial byproduct salt solution by the elution agent, so that the effective separation of the salt and water-soluble and fat-soluble impurities is realized, the COD removal rate can reach 92-97%, a high-purity refined salt product and a recyclable liquid-phase product are obtained, and the yield of the refined salt can reach 90-94%; therefore, the removal method has high COD removal rate and high refined salt yield, does not generate a large amount of industrial three wastes, and is a real high-efficiency and environment-friendly COD removal process.
(2) The treatment method for removing the industrial byproduct salt COD provided by the invention is simple and convenient to operate, can be realized at room temperature, does not need precise and complex instruments, is mild in condition, low in energy consumption and cost, and is easy for large-scale industrial popularization.
(3) The treatment method for removing the industrial byproduct salt COD provided by the invention can treat industrial byproduct salts with different sources and types, is a high-universality industrial byproduct salt resource regeneration process, and has a good application prospect.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
The experimental materials used in the following examples of the invention include:
industrial byproduct salt, namely crude industrial sodium chloride byproduct salt or crude industrial sodium sulfate byproduct salt from chemical plants, dye plants, pharmaceutical enterprises or pesticide enterprises in Shandong and Jiangsu; the elutriation agent and the reagent for testing COD are all commercial chemical products.
Example 1
The embodiment provides a treatment method for removing industrial byproduct salt COD, which comprises the following specific steps:
(1) preparing a saturated aqueous solution from a crude product (COD is 50000mg/kg) of industrial sodium chloride byproduct salt from a certain chemical plant in Shandong, adding a elutriation agent, namely absolute ethyl alcohol at the rate of 4mL/min, stirring and mixing at room temperature for 0.5h after the addition is finished to obtain a prefabricated slurry; the volume ratio of the saturated aqueous solution to the absolute ethyl alcohol is 1: 1;
(2) and (2) filtering the prefabricated slurry obtained in the step (1), drying a filter cake by air blowing to obtain refined sodium chloride, and returning the filtrate to the step (1) for recycling as a solvent.
Example 2
The embodiment provides a treatment method for removing industrial byproduct salt COD, which comprises the following specific steps:
(1) preparing a saturated aqueous solution from a crude product (COD is 5850mg/kg) of industrial sodium chloride byproduct salt from a certain chemical plant in Shandong, adding a elutriation agent, namely absolute ethyl alcohol at the rate of 0.8mL/min, stirring and mixing at room temperature for 1h after the addition is finished to obtain a prefabricated slurry; the volume ratio of the saturated aqueous solution to the absolute ethyl alcohol is 1: 2;
(2) and (2) centrifuging the prefabricated slurry obtained in the step (1), blowing and drying the precipitate to obtain refined sodium chloride, and returning the supernatant to the step (1) to be used as a dissolving-out agent for recycling after vacuum distillation.
Example 3
The embodiment provides a treatment method for removing industrial byproduct salt COD, which comprises the following specific steps:
(1) preparing a saturated aqueous solution from a crude product (COD is 14820mg/kg) of industrial sodium sulfate byproduct salt from a certain dye plant in Hebei, adding a elutriation agent, namely absolute ethyl alcohol at the speed of 2mL/min, stirring and mixing at room temperature for 1h after the addition is finished to obtain a prefabricated slurry; the volume ratio of the saturated aqueous solution to the absolute ethyl alcohol is 1: 1;
(2) and (2) filtering the prefabricated slurry obtained in the step (1), blowing and drying a filter cake to obtain refined sodium sulfate, and returning the filtrate to the step (1) after azeotropic distillation for recycling as a solvent or a solvent-out agent.
Example 4
The embodiment provides a treatment method for removing industrial byproduct salt COD, which comprises the following specific steps:
(1) preparing a saturated aqueous solution from a crude product (COD is 22740mg/kg) of industrial sodium chloride byproduct salt from a certain chemical plant in Jiangsu, adding a solvent-out agent methanol at the rate of 1mL/min, and stirring and mixing at room temperature for 0.5h after the addition is finished to obtain a prefabricated slurry; the volume ratio of the saturated aqueous solution to the methanol is 1: 5;
(2) and (2) filtering the prefabricated slurry obtained in the step (1), spray-drying a filter cake to obtain refined sodium chloride, and returning the filtrate to the step (1) after reduced pressure distillation for recycling as a dissolution agent.
Example 5
The embodiment provides a treatment method for removing industrial byproduct salt COD, which comprises the following specific steps:
(1) preparing a saturated aqueous solution from a crude product (COD is 2810mg/kg) of industrial sodium chloride byproduct salt from a certain chemical plant in Shandong, adding a solvent n-propanol into the saturated aqueous solution at a rate of 5mL/min, and stirring and mixing at room temperature for 0.5h after the addition is finished to obtain a prefabricated slurry; the volume ratio of the saturated aqueous solution to the n-propanol is 1: 8;
(2) and (2) filtering the prefabricated slurry obtained in the step (1), blowing and drying a filter cake to obtain refined sodium chloride, and returning the filtrate to the step (1) after reduced pressure distillation for recycling as a dissolution agent.
Example 6
The embodiment provides a treatment method for removing industrial byproduct salt COD, which comprises the following specific steps:
(1) preparing a saturated aqueous solution from a crude product (COD is 36940mg/kg) of industrial sodium sulfate byproduct salt from a certain chemical plant in Jiangsu, adding a solvent isopropanol into the saturated aqueous solution at the speed of 10mL/min, and stirring and mixing the mixture at room temperature for 0.5h after the addition is finished to obtain a prefabricated slurry; the volume ratio of the saturated aqueous solution to the isopropanol is 1: 10;
(2) and (2) filtering the prefabricated slurry obtained in the step (1), blowing and drying a filter cake to obtain refined sodium sulfate, distilling and recovering the filtrate, and returning the filtrate to the step (1) to be used as a dissolving-out agent for recycling.
Example 7
The embodiment provides a treatment method for removing industrial byproduct salt COD, which comprises the following specific steps:
(1) preparing a saturated aqueous solution from a crude product (COD is 43710mg/kg) of industrial sodium chloride byproduct salt from a certain Shandong pharmaceutical enterprise, adding a solvent ethanol into the saturated aqueous solution at a speed of 9mL/min, and stirring and mixing at room temperature for 2 hours after the addition is finished to obtain a prefabricated slurry; the volume ratio of the saturated aqueous solution to the ethanol is 1: 2;
(2) and (3) centrifuging the prefabricated slurry obtained in the step (1), blowing and drying the precipitate to obtain refined sodium chloride, and returning the supernatant to the step (1) for recycling as a solvent.
Example 8
The embodiment provides a treatment method for removing industrial byproduct salt COD, which comprises the following specific steps:
(1) preparing a saturated aqueous solution from a crude product (COD is 10430mg/kg) of industrial sodium chloride byproduct salt from a certain pesticide enterprise in Shandong, adding a solventing-out agent (a mixed solution of methanol and ethanol with the same volume) at the rate of 6mL/min, stirring and mixing at room temperature for 4 hours after the addition is finished, and obtaining a prefabricated slurry; the volume ratio of the saturated aqueous solution to the elution agent is 1: 4;
(2) and (2) centrifuging the prefabricated slurry obtained in the step (1), blowing and drying the precipitate to obtain refined sodium chloride, and returning the supernatant to the step (1) to be used as a solventing-out agent for recycling after azeotropic distillation and recovery.
Example 9
This example differs from example 1 in that the eluent was added at a rate of 0.5mL/min in step (1).
Example 10
This example differs from example 1 in that the eluent was added at a rate of 20mL/min in step (1).
Example 11
This example differs from example 1 in that the time for stirring and mixing in step (1) was 20 min.
Example 12
This example differs from example 1 in that the volume ratio of the saturated aqueous solution to absolute ethanol in step (1) is 1: 0.08.
Comparative example 1
This comparative example differs from example 1 in that the elution agent in step (1) is chloroform.
And (3) product testing:
(1) COD (mg/kg) test: the COD of the sample is tested by adopting a microwave seal digestion method, which comprises the following steps:
preparation of reagent
a. Potassium dichromate digestion solution: 19.60g of standard or high grade pure potassium dichromate dried at 120 ℃ for 2 hours is weighed and dissolved in about 500mL of distilled water, 250mL of concentrated sulfuric acid is slowly added while stirring, after cooling, the solution is transferred to a 1000mL volumetric flask, diluted to the marked line with distilled water and shaken up. The concentration of the potassium dichromate in the solution is 0.4mol/L, and the solution is used for determining a water sample with the COD concentration of 1000-2500 mg/L; and if the COD of the water sample is more than 2500mg/L, diluting the water sample and then testing by using the solution.
9.806g of potassium dichromate (with the same amount of added sulfuric acid) is weighed according to the method to prepare 0.2mol/L potassium dichromate digestion solution for determining a water sample with the COD concentration of 50-1000 mg/L.
2.45g of potassium dichromate (the amount of added sulfuric acid is the same) is weighed according to the method to prepare 0.05mo1/L potassium dichromate digestion solution for determining a water sample with COD concentration less than or equal to 50 mg/L.
b. Masking agent: mercury sulfate crystals or powder.
c. Catalyst: 10g of silver sulfate was weighed out and dissolved in l000mL of concentrated sulfuric acid and shaken up.
d. Ferrol indicator: 1.485g of phenanthroline and 0.695g of ferrous sulfate are weighed and dissolved in distilled water, diluted to 100mL and stored in a brown bottle.
e. Standard solution of ferrous ammonium sulfate: weighing 39.5g of analytically pure ferrous ammonium sulfate, dissolving the analytically pure ferrous ammonium sulfate in distilled water, slowly adding 20mL of concentrated sulfuric acid while stirring, cooling, transferring into a 1000mL volumetric flask, adding distilled water to dilute to a marked line, and shaking up to prepare a 0.1mol/L ferrous ammonium sulfate solution; in addition, 19.8g and 3.95g of ammonium ferrous sulfate (the amount of added sulfuric acid is the same) are weighed and prepared into 0.05mol/L and 0.0L mol/L ammonium ferrous sulfate solutions respectively according to the method; the concentration of the ammonium ferrous sulfate solution is calibrated by a potassium dichromate standard solution before use.
The calibration method comprises the following steps: accurately sucking 5mL of potassium dichromate standard solution (0.4mol/L) into a 150mL conical flask, adding distilled water to dilute to about 30mL, slowly adding 5mL of concentrated sulfuric acid, uniformly mixing, cooling, adding 2 drops of reagent ferron indicator, titrating with ferrous ammonium sulfate solution, recording the dosage (V/mL) of the ferrous ammonium sulfate solution, wherein the concentration C (mol/L) of the ferrous ammonium sulfate solution is 0.4 multiplied by 5.00/V, and the color of the solution is from yellow to reddish brown which is the end point.
e. Water sample to be detected:
industrial byproduct salt water sample: accurately weighing 1.65g of industrial byproduct salt, dissolving in distilled water, and diluting to 100 mL;
refining a salt water sample: 1.65g of refined salt is accurately weighed, dissolved in distilled water and diluted to 100 mL.
② testing step
a. Accurately absorbing 5mL of water sample to be tested (each batch of water sample needs 2 blank samples during testing) into a digestion tank, adding 1g of masking agent, and fully shaking up to enable Cl-With Hg2+Complete complexation (i.e. Cl if the masking agent is quickly dissolved)-If the content of the active component is too high, adding a masking agent until the masking agent is insoluble), shaking up 5mL of digestion solution and 5mL of catalyst;
b. screwing the sealing covers, uniformly placing the digestion tanks at the periphery of a glass turntable of a furnace chamber of the device in sequence, and closing a furnace door;
c. operating according to the operating method of a microwave digestion instrument, digesting the sample for n minutes plus (n multiplied by 12) seconds plus 20 seconds, wherein n is the number of the sample;
d. after digestion, the furnace door is opened, the digestion tank is taken out of the furnace after the digestion tank is cooled, and when the liquid in the tank is cooled to room temperature (the liquid can be vertically placed into a cold water basin if rapid cooling is needed), the COD value is measured by a titration method.
③ titration method
a. Transferring the sample solution into a 150mL conical flask, washing the inner walls of the digestion tank and the cover with 20mL of distilled water for three times, adding the washing solution into the conical flask, adding 2-3 drops of a ferroxyl indicator, dripping back with a ferrous ammonium sulfate standard solution, taking the end point that the color of the solution is changed from yellow to blue-green to reddish-brown, and recording the using amount of the ferrous ammonium sulfate standard solution;
b. the calculation method comprises the following steps:
COD(mg/kg)＝(V0-V1)×C×8×1000×V3/(V2×m)
wherein, V0Consumption of standard solution of ferrous ammonium sulfate (mL), V1The dosage (mL) of the standard solution of ferrous ammonium sulfate is consumed for a water sample, C is the concentration (mo1/L) of the standard solution of ferrous ammonium sulfate, V2Volume (mL), V, of the Industrial byproduct salt solution removed for digestion3The volume (L) of the industrial byproduct salt or the refined salt solution, and m is the mass (kg) of the industrial byproduct salt or the refined salt.
(2) Calculation of COD removal (%) ratio: the COD removal rate is (crude COD-refined salt COD)/crude COD.
(3) Yield of refined salt (%): the yield of the refined salt is (the quality of the crude product of the industrial byproduct salt-the quality of the refined salt)/the quality of the crude product of the industrial byproduct salt.
The COD, COD removal rate and yield of the refined salt products obtained in examples 1 to 12 were measured according to the above methods, and the specific data are shown in table 1:
TABLE 1
As can be seen from the data in table 1, the removal method of the industrial byproduct salt COD provided in embodiments 1 to 9 of the present invention can achieve effective removal of the industrial byproduct salt COD, the COD removal rate is more than 92%, even 96.94%, and the yield of the refined salt can reach 90 to 94%. In the embodiment 10, the addition rate of the elutriation agent is more than 10mL/min, so that salts rapidly nucleate and grow under high degree of over saturation, and more industrial byproduct salt solution containing impurities is occluded in crystals, so that the COD removal rate is reduced; in example 11, the stirring and mixing time after the completion of the addition of the elution agent is less than 0.5h, so that the elution crystallization is incomplete, and the yield of the refined salt product is reduced; in example 12, the addition of less elution reagent than the preferred range of the present invention resulted in incomplete crystallization of the salt, which also resulted in a lower yield of the refined salt product. If the elution agent defined in the present invention is not used (comparative example 1), salts and water-soluble and fat-soluble impurities cannot be separated effectively, and the technical effects of removing COD and obtaining refined salts with high yield cannot be achieved.
The applicant states that the present invention is described by the above examples to the treatment method for removing COD as an industrial byproduct salt of the present invention, but the present invention is not limited to the above examples, i.e., it is not meant that the present invention is implemented by relying on the above examples. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (10)
1. A treatment method for removing industrial byproduct salt COD is characterized by comprising the following steps:
(1) adding a dissolving-out agent into the industrial byproduct salt solution, and mixing to obtain prefabricated slurry;
(2) and (2) performing solid-liquid separation on the prefabricated slurry obtained in the step (1), and drying a solid phase obtained by the solid-liquid separation to obtain a refined salt product.
2. The treatment method according to claim 1, wherein the solvent of the industrial byproduct salt solution of step (1) is water or an aqueous solution of an organic solvent;
preferably, the organic solvent is selected from any one of methanol, ethanol, n-propanol, isopropanol or acetone or a combination of at least two of the above;
preferably, the volume percentage of the organic solvent in the aqueous solution of the organic solvent is 0.5-50%;
preferably, the industrial byproduct salt solution in the step (1) is a saturated aqueous solution of the industrial byproduct salt.
3. The treatment method according to claim 1 or 2, wherein the industrial byproduct salt in the step (1) comprises an industrial chloride byproduct salt, an industrial byproduct sulfate or an industrial byproduct sulfite;
preferably, the COD content of the industrial byproduct salt in the step (1) is 100-100000 mg/kg;
preferably, the industrial chloride byproduct salt is a sodium chloride byproduct salt;
preferably, the industrial by-product sulfate is a sodium sulfate by-product salt.
4. The process according to any one of claims 1 to 3, wherein the elution solvent in step (1) is a water-miscible organic solvent;
preferably, the water-miscible organic solvent is a water-miscible ketone solvent and/or a water-miscible alcohol solvent;
preferably, the elution agent in the step (1) is selected from any one or a combination of at least two of methanol, ethanol, n-propanol, isopropanol or acetone;
preferably, the boiling point of the elution reagent in the step (1) is not higher than 110 ℃.
5. The treatment method according to any one of claims 1 to 4, wherein the volume ratio of the industrial byproduct salt solution to the elutriation agent in the step (1) is 1 (0.1 to 10), preferably 1 (0.2 to 5).
6. The process according to any one of claims 1 to 5, wherein the rate of addition of the elution reagent in step (1) is 0.5 to 10 mL/min.
7. The process of any one of claims 1 to 6, wherein the temperature of the mixing in step (1) is 10 to 100 ℃, preferably room temperature;
preferably, the mixing time in the step (1) is 0.5-12 h, and further preferably 0.5-3 h;
preferably, the mixing of step (1) is carried out under stirring conditions.
8. The removal method of any one of claims 1 to 7, wherein the solid-liquid separation method in the step (2) comprises swirling, settling, filtering or centrifuging.
9. The removal method of any one of claims 1 to 8, wherein the drying method in the step (2) comprises natural air drying, air blast drying, freeze drying, spray drying or flash drying.
10. The removal method according to any one of claims 1 to 9, wherein the treatment method comprises the steps of:
(1) adding a solvent-out agent into the industrial byproduct salt solution at the rate of 0.5-10 mL/min, and stirring and mixing at 10-100 ℃ for 0.5-12 h to obtain a prefabricated slurry; the volume ratio of the saturated aqueous solution of the industrial byproduct salt to the elution agent is 1 (0.1-10);
(2) and (2) performing solid-liquid separation on the prefabricated slurry obtained in the step (1), and drying a solid phase obtained by the solid-liquid separation to obtain a refined salt product.
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