CN110877900A - Mixed salt recycling treatment method and system - Google Patents
Mixed salt recycling treatment method and system Download PDFInfo
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- CN110877900A CN110877900A CN201910258240.4A CN201910258240A CN110877900A CN 110877900 A CN110877900 A CN 110877900A CN 201910258240 A CN201910258240 A CN 201910258240A CN 110877900 A CN110877900 A CN 110877900A
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- 238000000034 method Methods 0.000 title claims abstract description 109
- 238000004064 recycling Methods 0.000 title claims abstract description 75
- 238000000909 electrodialysis Methods 0.000 claims abstract description 213
- 239000012528 membrane Substances 0.000 claims abstract description 205
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 193
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 190
- 239000002253 acid Substances 0.000 claims abstract description 155
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 150
- 238000000926 separation method Methods 0.000 claims abstract description 113
- 239000007788 liquid Substances 0.000 claims abstract description 105
- 239000012266 salt solution Substances 0.000 claims abstract description 53
- 235000011121 sodium hydroxide Nutrition 0.000 claims abstract description 50
- 238000004519 manufacturing process Methods 0.000 claims abstract description 36
- -1 salt ions Chemical class 0.000 claims abstract description 33
- 238000010306 acid treatment Methods 0.000 claims abstract description 9
- 239000003513 alkali Substances 0.000 claims description 65
- 230000008569 process Effects 0.000 claims description 59
- 238000003860 storage Methods 0.000 claims description 53
- 238000001704 evaporation Methods 0.000 claims description 49
- 230000008020 evaporation Effects 0.000 claims description 49
- 238000001035 drying Methods 0.000 claims description 34
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- 238000001728 nano-filtration Methods 0.000 claims description 33
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 32
- 150000001768 cations Chemical class 0.000 claims description 32
- 239000007921 spray Substances 0.000 claims description 30
- 150000001450 anions Chemical class 0.000 claims description 27
- 239000013505 freshwater Substances 0.000 claims description 27
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- 229910001424 calcium ion Inorganic materials 0.000 claims description 26
- 229910001425 magnesium ion Inorganic materials 0.000 claims description 26
- 239000007787 solid Substances 0.000 claims description 24
- 239000000126 substance Substances 0.000 claims description 22
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 21
- 238000003756 stirring Methods 0.000 claims description 19
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 13
- 229910002651 NO3 Inorganic materials 0.000 claims description 13
- 229910052799 carbon Inorganic materials 0.000 claims description 13
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 12
- 229910001415 sodium ion Inorganic materials 0.000 claims description 12
- 150000002500 ions Chemical class 0.000 claims description 11
- 229910001414 potassium ion Inorganic materials 0.000 claims description 11
- 238000002156 mixing Methods 0.000 claims description 10
- 239000000377 silicon dioxide Substances 0.000 claims description 10
- 239000002585 base Substances 0.000 claims description 9
- 229910001385 heavy metal Inorganic materials 0.000 claims description 9
- 229910052681 coesite Inorganic materials 0.000 claims description 8
- 229910052906 cristobalite Inorganic materials 0.000 claims description 8
- 125000005842 heteroatom Chemical group 0.000 claims description 8
- 229910052682 stishovite Inorganic materials 0.000 claims description 8
- 229910052905 tridymite Inorganic materials 0.000 claims description 8
- 238000004090 dissolution Methods 0.000 claims description 7
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 claims description 6
- 239000003456 ion exchange resin Substances 0.000 claims description 6
- 229920003303 ion-exchange polymer Polymers 0.000 claims description 6
- 238000004062 sedimentation Methods 0.000 claims description 6
- 238000000108 ultra-filtration Methods 0.000 claims description 6
- 239000000084 colloidal system Substances 0.000 claims description 2
- 230000014759 maintenance of location Effects 0.000 claims description 2
- 239000003518 caustics Substances 0.000 claims 2
- 230000007613 environmental effect Effects 0.000 abstract description 6
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 24
- 238000002425 crystallisation Methods 0.000 description 13
- 230000008025 crystallization Effects 0.000 description 13
- 239000005416 organic matter Substances 0.000 description 13
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 12
- 239000006227 byproduct Substances 0.000 description 12
- 239000001569 carbon dioxide Substances 0.000 description 12
- 229910002092 carbon dioxide Inorganic materials 0.000 description 12
- 238000002485 combustion reaction Methods 0.000 description 12
- 238000002203 pretreatment Methods 0.000 description 12
- 238000005265 energy consumption Methods 0.000 description 8
- 238000012423 maintenance Methods 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 238000007599 discharging Methods 0.000 description 7
- 239000002910 solid waste Substances 0.000 description 7
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 6
- 229910017053 inorganic salt Inorganic materials 0.000 description 6
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 6
- 229910017604 nitric acid Inorganic materials 0.000 description 6
- 238000006864 oxidative decomposition reaction Methods 0.000 description 6
- 230000001590 oxidative effect Effects 0.000 description 6
- 238000004065 wastewater treatment Methods 0.000 description 5
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 4
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical group [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 4
- 238000011161 development Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 4
- 239000002351 wastewater Substances 0.000 description 4
- NPYPAHLBTDXSSS-UHFFFAOYSA-N Potassium ion Chemical compound [K+] NPYPAHLBTDXSSS-UHFFFAOYSA-N 0.000 description 3
- 238000009776 industrial production Methods 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000001117 sulphuric acid Substances 0.000 description 2
- 235000011149 sulphuric acid Nutrition 0.000 description 2
- HGUFODBRKLSHSI-UHFFFAOYSA-N 2,3,7,8-tetrachloro-dibenzo-p-dioxin Chemical compound O1C2=CC(Cl)=C(Cl)C=C2OC2=C1C=C(Cl)C(Cl)=C2 HGUFODBRKLSHSI-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 238000010170 biological method Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
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- 238000012827 research and development Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 238000001694 spray drying Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/69—Sulfur trioxide; Sulfuric acid
- C01B17/74—Preparation
- C01B17/745—Preparation from sulfates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
- C01B13/14—Methods for preparing oxides or hydroxides in general
- C01B13/32—Methods for preparing oxides or hydroxides in general by oxidation or hydrolysis of elements or compounds in the liquid or solid state or in non-aqueous solution, e.g. sol-gel process
- C01B13/326—Methods for preparing oxides or hydroxides in general by oxidation or hydrolysis of elements or compounds in the liquid or solid state or in non-aqueous solution, e.g. sol-gel process of elements or compounds in the liquid state
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
- C01B21/38—Nitric acid
- C01B21/42—Preparation from nitrates
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B7/00—Halogens; Halogen acids
- C01B7/01—Chlorine; Hydrogen chloride
- C01B7/03—Preparation from chlorides
- C01B7/035—Preparation of hydrogen chloride from chlorides
-
- 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
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
- C02F1/4693—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- Electrochemistry (AREA)
- Analytical Chemistry (AREA)
- Molecular Biology (AREA)
- Health & Medical Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Water Treatment By Electricity Or Magnetism (AREA)
Abstract
The invention discloses a method and a system for recycling mixed salt, wherein the method comprises the steps of 1) dissolving mixed salt, 2) performing bipolar membrane electrodialysis separation, 3) performing acid treatment, and 4) performing electrodialysis concentration; the system comprises a dissolving tank, a reuse water tank, a bipolar membrane electrodialysis separation system and an electrodialysis concentration system. The method has the advantages that the problems that the conventional miscellaneous salt cannot be eliminated and is excessively stacked and accumulated are solved, and the environmental problem caused by direct landfill of the miscellaneous salt is relieved; separating and collecting salt ions in the mixed salt solution by using a bipolar membrane electrodialysis separation system to finally obtain at least one of high-purity monovalent monoacid, monovalent mixed acid and sulfuric acid and liquid caustic soda; the obtained high-purity liquid caustic soda, sulfuric acid and monovalent acid are concentrated and then are used for self or sold for outside, so that the production diversity and the income of enterprises are improved; the reuse water obtained by concentration is recycled to the system, so that the utilization rate of water resources is high; the recycling rate of the miscellaneous salt treatment can reach 70-95%, and the purposes of harmless and recycling treatment of miscellaneous salt are really realized.
Description
The technical field is as follows:
the invention relates to the field of industrial waste treatment, in particular to a method and a system for recycling mixed salt.
Background art:
the miscellaneous salt is a solid waste, is mainly generated by industrial production and wastewater treatment, is used as a dangerous waste, and has no reasonable and effective method or means for treatment, so that the miscellaneous salt treatment becomes a bottleneck for hindering the development of the environmental protection technology.
The production of the miscellaneous salt in the industrial production is mainly that in the actual production process, due to the problems of annual inspection of enterprises, operation and maintenance of equipment, sudden accidents and the like, the normal production process is forced to be interrupted, and raw materials cannot be reasonably converted into products and are discharged in the form of miscellaneous salt. Or the product is unqualified due to unreasonable control of production conditions, manual operation errors, mechanical equipment faults and the like, and is discharged in the form of miscellaneous salt. In conclusion, the production of miscellaneous salts is inevitable and the production amount is huge in the production process of industrial enterprises.
In the field of wastewater treatment, with the development of economy in China, population is growing continuously, cities and industrial enterprises are increasing and expanding day by day, water consumption in various regions is increasing continuously, wastewater yield is huge, China is relatively lack of water resources, and the per-capita water resource is only 28% of the per-capita water resource in the world, so how to fully and effectively utilize waterResources have become the key aspect of our country in breaking through and research and development. In recent years, with the increasing attention of the country on environmental protection, the strengthening of the enforcement of environmental protection and the continuous development and maturity of sewage treatment technology, most enterprises begin to implement wastewater treatment, the wastewater discharge amount is reduced year by year, but the miscellaneous salts generated in the wastewater treatment process are more and more. The waste water treatment method usually adopts a physical and chemical method, a biological method or a combination of the physical and chemical methods for treatment and the like as pretreatment, and finally realizes the complete recycling of water resources through evaporation and crystallization. However, the salt content in the waste water is continuously concentrated and finally directly changed into solid miscellaneous salt in a dry state. The salt in the mixed salt is Na+、Mg2+、Ca2+、K+、Cl～、SO4 2～、NO3～In addition, the wastewater usually contains various organic substances, heavy metal ions, and Fe3+、F～、NO2～And the like. These miscellaneous salts are often characterized by complex components, serious environmental pollution, heavy odor, easy volatilization, difficult treatment and the like.
At present, the treatment of the miscellaneous salt is mainly landfilled or dumped, but because the solubility of the miscellaneous salt is extremely strong, but the stability and the curing property are extremely poor, if the miscellaneous salt is not properly treated, secondary environmental pollution is easily caused, and the miscellaneous salt is defined as dangerous waste. And part of enterprises also adopt an incineration method to remove organic matters in the miscellaneous salts, but the method has the disadvantages of huge equipment investment, serious equipment depreciation and dioxin pollution risk. With the enhancement of national environmental protection regulation, the requirements on the types of dangerous wastes for landfill, stacking or incineration are increasingly strict, the continuous and stable healthy green development of industrial production is limited, the daily life of people is influenced, and for the problems, no relevant effective solution is disclosed or reported in any literature.
The invention content is as follows:
the first purpose of the invention is to provide a method for recycling mixed salt, which has low treatment cost and low treatment difficulty.
The second purpose of the invention is to provide a miscellaneous salt recycling treatment system which can recycle miscellaneous salt with low treatment cost and low treatment difficulty.
The first purpose of the invention is implemented by the following technical scheme: the method for recycling mixed salt comprises the following steps:
1) dissolving miscellaneous salt: dissolving miscellaneous salt in water with the volume of 5-20 times, and stirring to fully dissolve the miscellaneous salt until no solid matter exists, so as to obtain miscellaneous salt liquid; the hetero salt is composed of univalent cations and/or bivalent cations, the univalent anions and/or bivalent anions, the univalent cations comprise any one of sodium ions or potassium ions, the bivalent cations comprise any one of calcium ions or magnesium ions or the combination of calcium ions and magnesium ions, the univalent anions comprise any one of chloride ions, nitrate ions, bicarbonate ions or hydroxide ions or the combination of chloride ions, nitrate ions, bicarbonate ions or the combination of hydroxide ions, and the bivalent anions comprise any one of sulfate ions and carbonate ions or the combination of sulfate ions and carbonate ions;
2) bipolar membrane electrodialysis separation: after the 1) mixed salt is dissolved, removing carbonate ions and bicarbonate ions in the mixed salt solution to obtain a pretreated mixed salt solution; introducing the pretreated mixed salt solution into a bipolar membrane electrodialysis separation system for acid-base separation, wherein the operating voltage of bipolar membrane electrodialysis is 50-100V, and the current density is controlled to be 200-1000A/m2The concentration of the alkali chamber is 6 to 9 percent, and the concentration of the acid chamber is 6 to 8 percent; separating to obtain liquid alkali, acid and fresh water;
3) acid treatment: after the bipolar membrane electrodialysis separation is finished, if the acid comprises monovalent acid and divalent acid, conveying the acid into a nanofiltration membrane system for separation, wherein the retention rate of sulfate ions of the nanofiltration membrane system is more than or equal to 99%, and separating to obtain monovalent monoacid or monovalent mixed acid and sulfuric acid; if the acid only comprises the monovalent acid or the divalent acid, the acid is not separated to obtain any one of monovalent monoacid, monovalent mixed acid or sulfuric acid;
4) and (3) electrodialysis concentration: and 2) after the bipolar membrane electrodialysis separation is finished, conveying the fresh water into an electrodialysis concentration system for concentration, wherein the operation pressure of the electrodialysis concentration is 0.5-3.0 kg/cm2The operating voltage is 100-250V, and the current is 1-3A; is separated to obtainAnd mixing the electrodialysis concentrated water with the miscellaneous salt solution, and conveying the electrodialysis produced water into a spray dryer to obtain a dried substance.
Further, the 1) dissolving of the miscellaneous salt specifically comprises: and mixing the mixed salt with water, stirring and dissolving for 10-120 min under the condition that the rotating speed is 300-1000 rpm so as to fully dissolve the mixed salt, and obtaining the mixed salt solution after stirring.
Further, in the 2) bipolar membrane electrodialysis separation, suspended matters, particles, colloids and silicon dioxide are removed from the pretreated mixed salt solution, and finally the indexes of the mixed salt solution are as follows: calcium ion concentration < 150mg/L, magnesium ion concentration < 200mg/L, carbonate ion concentration < 50mg/L, bicarbonate ion concentration < 50mg/L, SiO2The concentration is less than 200mg/L, the COD content is less than 200mg/L, and the concentration of heavy metal ions is less than 0.1 mg/L.
Further, in the 4) electrodialysis concentration, the electrodialysis water is concentrated by a membrane and then conveyed into the spray dryer.
Further, the liquid alkali obtained in the 2) bipolar membrane electrodialysis separation is concentrated to obtain concentrated liquid alkali; the 3) acid-treating the obtained monovalent mono-acid, the monovalent mixed acid, the sulfuric acid, the monovalent mono-acid and the sulfuric acid, or the monovalent mixed acid and the sulfuric acid, concentrating, if the concentration object is the monovalent mono-acid and the sulfuric acid or the monovalent mixed acid and the sulfuric acid, respectively and independently concentrating the monovalent mono-acid and the sulfuric acid, or the monovalent mixed acid and the sulfuric acid; and (3) recycling water obtained in the concentration process to the dissolution of the mixed salt in the step 1).
Further, the concentration is membrane concentration or evaporation concentration.
The second purpose of the invention is implemented by the following technical scheme: the mixed salt recycling treatment system comprises a dissolving tank, a reuse water tank, a bipolar membrane electrodialysis separation system and an electrodialysis concentration system, wherein a solid inlet of the dissolving tank is connected with an outlet of a mixed salt bin, a liquid inlet of the dissolving tank is connected with an outlet of the reuse water tank, an outlet of the dissolving tank is connected with an inlet of a carbon remover, and an outlet of the carbon remover is connected with an inlet of the bipolar membrane electrodialysis separation system; the liquid alkali outlet of the bipolar membrane electrodialysis separation system is connected with the inlet of the liquid alkali storage tank, and the acid outlet of the bipolar membrane electrodialysis separation system is connected with the inlet of the nanofiltration membrane system; a concentrated water outlet of the nanofiltration membrane system is connected with an inlet of a sulfuric acid storage tank, and a water production outlet of the nanofiltration membrane system is connected with an inlet of a monovalent acid storage tank; the acid outlet of the bipolar membrane electrodialysis separation system is also connected with the inlet of the monovalent acid storage tank through a first overrunning pipeline, and the acid outlet of the bipolar membrane electrodialysis separation system is also connected with the inlet of the sulfuric acid storage tank through a second overrunning pipeline; the fresh water outlet of the bipolar membrane electrodialysis separation system is connected with the inlet of the electrodialysis concentration system, the water production outlet of the electrodialysis concentration system is connected with the inlet of the spray dryer, and the concentrated water outlet of the electrodialysis concentration system is connected with the inlet of the reuse water pool.
Furthermore, a stirrer is arranged in the dissolving tank.
Further, the device also comprises a miscellaneous salt pretreatment system, wherein the inlet of the pretreatment system is connected with the outlet of the miscellaneous salt dissolving tank, and the outlet of the pretreatment system is connected with the inlet of the bipolar membrane electrodialysis separation system; the pretreatment system comprises a high-density sedimentation tank, an immersed ultrafiltration, ion exchange resin and a carbon remover, wherein an outlet of a dissolving tank is connected with an inlet of the high-density sedimentation tank, an outlet of the high-density sedimentation tank is connected with an inlet of the immersed ultrafiltration membrane, an outlet of the immersed ultrafiltration membrane is connected with an inlet of the ion exchange resin, an outlet of the ion exchange resin is connected with an inlet of the carbon remover, and an outlet of the carbon remover is connected with an inlet of the bipolar membrane electrodialysis separation system.
Further, the device also comprises a deep concentration system, wherein the deep concentration system comprises a liquid alkali deep concentration system, a sulfuric acid deep concentration system and an acid deep concentration system, a liquid alkali outlet of the bipolar membrane electrodialysis separation system is connected with an inlet of the liquid alkali deep concentration system, and a concentrated water outlet of the liquid alkali deep concentration system is connected with the liquid alkali storage tank; a concentrated water outlet of the nanofiltration membrane system is connected with an inlet of the sulfuric acid deep concentration system through the second overrunning pipeline, and a concentrated water outlet of the sulfuric acid deep concentration system is connected with the sulfuric acid storage tank; a water production outlet of the nanofiltration membrane system is connected with an inlet of the acid deep concentration system through the first overrunning pipeline, and a concentrated water outlet of the acid deep concentration system is connected with the monovalent acid storage tank; and the water production outlet of the liquid caustic soda deep concentration system, the water production outlet of the sulfuric acid deep concentration system and the water production outlet of the acid deep concentration system are all connected with the inlet of the reuse water pool.
Further, the liquid caustic soda deep concentration system, the sulfuric acid deep concentration system and the acid deep concentration system are any one or a combination of several of a membrane concentration system, an electrodialysis system, an MVR evaporation system, a TVR evaporation system or a multi-effect evaporation system.
Furthermore, a water production outlet of the electrodialysis concentration system is connected with an inlet of a drying concentration system, a concentrated water outlet of the drying concentration system is connected with an inlet of the spray dryer, and the drying concentration system is a membrane concentration system.
The invention has the advantages that: 1. the problems that conventional miscellaneous salt cannot be eliminated and excessive stacking and accumulation are solved, the quantity of miscellaneous salt is effectively reduced, and the environmental problem caused by direct landfill of miscellaneous salt is relieved; separating and collecting salt ions in the miscellaneous salt by using a bipolar membrane electrodialysis separation system, an electrodialysis concentration system and the like to finally obtain at least one of high-purity univalent monoacid, univalent mixed acid and sulfuric acid and liquid alkali; the recycling treatment of the miscellaneous salt is realized; 2. the obtained high-purity liquid caustic soda, sulfuric acid, monovalent monoacid and monovalent mixed acid are subjected to membrane concentration and then are used for self or sold, so that the recycling of mixed salt resources is realized, and the production diversity and income of enterprises are improved; the reuse water obtained by concentration is recycled to the system, so that the utilization rate of water resources is high; the method realizes resource utilization of the mixed salt which cannot be effectively treated originally after treatment, the resource rate of the mixed salt treatment can reach 70-95%, and the purposes of harmless and resource treatment of the mixed salt are really realized; 3. the method is characterized in that the method comprises the following steps of utilizing the non-conductivity of organic matters, leaving most of the organic matters in the miscellaneous salt in fresh water of a bipolar membrane electrodialysis separation system, treating the fresh water by an electrodialysis concentration system, utilizing the non-conductivity of the organic matters, intercepting and concentrating salt ions contained in bipolar membrane electrodialysis production water, returning formed electrodialysis concentrated water to the system, improving the utilization rate of the salt ions, carrying out spray drying on a large amount of organic matters contained in the rest electrodialysis production water accounting for 0.5-1.5% of the total treatment water quantity of the system, and thoroughly discharging the organic matters in the miscellaneous salt out of the system, so that the enrichment of the organic matters in the miscellaneous salt recycling process is avoided; 4. through the combination of various systems, the concentration of the organic matters is finally concentrated to the fresh water side of the electrodialysis concentration system, the concentration of the organic matters reaches 5-10 times of the concentration of the raw materials, the treatment efficiency is high, and the treatment scale and the treatment cost of the organic matters are greatly reduced; 5. the process equipment used by the invention only comprises three types of membranes such as a bipolar membrane electrodialysis separation system, an electrodialysis concentration system and a membrane concentration system, the whole system is operated at normal temperature and normal pressure with low energy consumption, the investment and the operation cost are greatly reduced, and the whole process flow is short, the operation is simple and the operation and maintenance are convenient. 6. The comprehensive overall cost of the treatment of the miscellaneous salt per ton is reduced by 90 to 98 percent compared with the operation cost of the traditional process;
description of the drawings:
in order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of the overall structure of a mixed salt recycling system.
Dissolving tank 1, reuse water tank 2, bipolar membrane electrodialysis separation system 3, nanofiltration membrane system 4, electrodialysis concentration system 5, miscellaneous salt storehouse 6, liquid caustic soda storage tank 7, sulphuric acid storage tank 8, monovalent acid storage tank 9, spray dryer 10, liquid caustic soda degree of depth concentration system 11, sulphuric acid degree of depth concentration system 12, acid degree of depth concentration system 13, decarbonizer 14, first pipeline 15 that surpasss, the second surpasss pipeline 16, dry concentration system 17.
The specific implementation mode is as follows:
example 1:
as shown in fig. 1, the mixed salt recycling treatment system comprises a dissolving tank 1, a reuse water tank 2, a bipolar membrane electrodialysis separation system 3 and an electrodialysis concentration system 5; a solid inlet of the dissolving tank 1 is connected with an outlet of the miscellaneous salt bin 6 through a conveyer belt, a liquid inlet of the dissolving tank 1 is connected with an outlet of the reuse water tank 2 through a pipeline, a stirrer is arranged in the dissolving tank 1, and the miscellaneous salt and water conveyed into the dissolving tank 1 are mixed by the stirrer to ensure that the miscellaneous salt is fully dissolved; the outlet of the dissolving tank 1 is connected with the inlet of a carbon remover 14, and the carbon remover 14 can remove bicarbonate ions and carbonate ions in the mixed salt solution; the outlet of the carbon remover 14 is connected with the inlet of the bipolar membrane electrodialysis separation system 3, the bipolar membrane electrodialysis separation system 3 utilizes the permeability of the membrane to block organic matters, suspended matters and insoluble scaling substances with poor solubility in the miscellaneous salt on the fresh water side, and the fresh water accounts for 20-40% of the treatment capacity of the miscellaneous salt dissolved water; the water and salt ions permeating the membrane are separated and aggregated under the action of an electric field, and finally high-purity acid and liquid alkali are obtained, wherein the acid can be a simple acid, such as hydrochloric acid or nitric acid or sulfuric acid, or can be mixed acid; a liquid caustic soda outlet of the bipolar membrane electrodialysis separation system 3 is connected with an inlet of a liquid caustic soda storage tank 7; when the bipolar membrane electrodialysis separation system 3 separates pure acid, the pure acid enters a monovalent acid storage tank 9 or a sulfuric acid storage tank 8 through a first exceeding pipeline 15 or a second exceeding pipeline 16; when the mixed acid is obtained by separating the bipolar membrane electrodialysis separation system 3, an acid outlet of the bipolar membrane electrodialysis separation system 3 is connected with an inlet of a nanofiltration membrane system 4 through a pipeline, the mixed acid obtained by separating the bipolar membrane electrodialysis separation system 3 is conveyed to the nanofiltration membrane system 4 for further separation, the rejection rates of the nanofiltration membrane system 4 on monovalent ions (mainly chloride ions and nitrate ions) and divalent ions (sulfate ions) are different, and the mixed acid is further separated to obtain monovalent mixed acid mainly comprising hydrochloric acid and nitric acid and high-purity sulfuric acid; a concentrated water outlet of the nanofiltration membrane system 4 is connected with an inlet of the sulfuric acid storage tank 8 through a pipeline, and a produced water outlet of the nanofiltration membrane system 4 is connected with an inlet of the monovalent acid storage tank 9 through a pipeline; a fresh water outlet of the bipolar membrane electrodialysis separation system 3 is connected with an inlet of the electrodialysis concentration system 5 through a pipeline, a water production outlet of the electrodialysis concentration system 5 is connected with an inlet of the drying concentration system 17 through a pipeline, a concentrated water outlet of the drying concentration system 17 is connected with an inlet of the spray dryer 10 through a pipeline, and a concentrated water outlet of the electrodialysis concentration system 5 is connected with the reflux water tank 2 through a pipeline; in this embodiment, the drying and concentrating system 17 is a membrane concentrating system, and is used for concentrating the water produced by the electrodialysis concentrating system 5, so as to reduce the treatment capacity of the spray dryer 10 and reduce the energy consumption and treatment cost; organic matters, suspended matters and insoluble scaling substances which are intercepted at the fresh water side of the bipolar membrane electrodialysis separation system 3 and have poor solubility are conveyed to an electrodialysis concentration system 5 for further separation and concentration treatment, salt ions are separated as far as possible and flow back to the system through a backflow water tank 2, and the utilization rate of the salt ions is improved; finally, the organic matter, suspended matter and insoluble scaling substance with poor solubility are concentrated by a drying and concentrating system 17, dried by a spray dryer and discharged.
The device also comprises a deep concentration system, wherein the deep concentration system comprises a liquid alkali deep concentration system 11, a sulfuric acid deep concentration system 12 and an acid deep concentration system 13, a liquid alkali outlet of the bipolar membrane electrodialysis separation system 3 is connected with an inlet of the liquid alkali deep concentration system 11, a concentrated water outlet of the liquid alkali deep concentration system 11 is connected with a liquid alkali storage tank 7, and liquid alkali generated by the bipolar membrane electrodialysis separation system 3 is concentrated by the liquid alkali deep concentration system 11 and then is conveyed to the liquid alkali storage tank 7 for storage; a concentrated water outlet of the nanofiltration membrane system 4 is connected with an inlet of a sulfuric acid deep concentration system 12, a concentrated water outlet of the sulfuric acid deep concentration system 12 is connected with a sulfuric acid storage tank 8 through a second overrunning pipeline 16, sulfuric acid generated by the nanofiltration membrane system 4 is concentrated by the sulfuric acid deep concentration system 12, and concentrated sulfuric acid is obtained and conveyed to the sulfuric acid storage tank 8 for storage; the water outlet of the nanofiltration membrane system 4 is connected with the inlet of the acid deep concentration system 13, the concentrated water outlet of the acid deep concentration system 13 is connected with the monovalent acid storage tank 9 through a first surpassing pipeline 15, the acid generated by the nanofiltration membrane system 4 is concentrated by the acid deep concentration system 13 to obtain concentrated monovalent single acid (i.e. pure monovalent acid) or concentrated monovalent mixed acid (i.e. monovalent acid mainly comprising hydrochloric acid and nitric acid) and is conveyed to the monovalent acid storage tank 9 for storage; the water outlet of the liquid caustic soda deep concentration system 11, the water outlet of the sulfuric acid deep concentration system 12 and the water outlet of the acid deep concentration system 13 are all connected with the inlet of the reuse water pool 2 through pipelines, reuse water generated by deep concentration flows back to the reuse water pool 2, and the amount of the return water in the whole system accounts for 90-98% of the total amount of the miscellaneous salt dissolving water; the liquid caustic soda depth concentration system 11, the sulfuric acid depth concentration system 12 and the acid depth concentration system 13 are any one or a combination of several of a membrane concentration system, an electrodialysis system, an MVR evaporation system, a TVR evaporation system and a multi-effect evaporation system, in this embodiment, the liquid caustic soda depth concentration system 11 is a membrane concentration system, the sulfuric acid depth concentration system 12 is a multi-effect evaporation system, and the acid depth concentration system 13 is an MVR evaporation system.
The working process is as follows:
conveying the miscellaneous salt stored in the miscellaneous salt bin 6 into the dissolving tank 1 through a conveying belt, conveying water from the reuse water tank 2 to the dissolving tank 1, wherein the volume of the water is 3-5 times of that of the miscellaneous salt, and stirring the water through a stirrer to fully dissolve the miscellaneous salt in the dissolving tank 1 to obtain miscellaneous salt liquid; the mixed salt solution is conveyed to a bipolar membrane electrodialysis separation system 3 for treatment, the bipolar membrane electrodialysis separation system 3 blocks organic matters, suspended matters and insoluble scaling substances with poor solubility in the mixed salt solution on the fresh water side by utilizing the permeability of a membrane, and water and salt ions passing through the membrane are separated and gathered under the action of an electric field, so that high-purity acid and liquid caustic soda are finally obtained; the liquid caustic soda is concentrated by a liquid caustic soda deep concentration system 11 and then stored in a liquid caustic soda storage tank 7; when the bipolar membrane electrodialysis separation system 3 separates pure acid, the pure acid enters a monovalent acid storage tank 9 or a sulfuric acid storage tank 8 through a first exceeding pipeline 15 or a second exceeding pipeline 16; when the mixed acid is obtained by separation in the bipolar membrane electrodialysis separation system 3, the mixed acid is conveyed to the nanofiltration membrane system 4 for further separation, and the mixed acid is further separated to obtain mixed acid mainly comprising hydrochloric acid and nitric acid and high-purity sulfuric acid; the mixed acid is concentrated by an acid deep concentration system 13 and then stored in a monovalent acid storage tank 9, and the sulfuric acid is concentrated by a sulfuric acid deep concentration system 12 and then stored in a sulfuric acid storage tank 8; the liquid caustic soda, the sulfuric acid and the mixed acid can be used or sold for outside, the recycling of miscellaneous salt resources is realized, the production diversity and the income of enterprises are improved, the recycled water obtained by concentration is recycled to the system, and the utilization rate of water resources is high; fresh water generated by the bipolar membrane electrodialysis separation system 3 is conveyed to the electrodialysis concentration system 5 for separation and concentration treatment, salt ions are separated as much as possible and flow back to the system, and the utilization rate of the salt ions is improved; finally, the organic matters with poor solubility, suspended matters and insoluble scaling substances are dried by a spray dryer and then discharged.
Example 2:
the method for recycling mixed salt according to example 1, comprising the steps of:
1) dissolving miscellaneous salt: dissolving miscellaneous salt in water with volume 5 times, stirring and dissolving for 10min at the rotation speed of 1000rpm, and stirring to fully dissolve the miscellaneous salt until no solid matter exists, thereby obtaining miscellaneous salt solution; the heterosalt is composed of univalent cations and/or bivalent cations, and/or univalent anions and/or bivalent anions, wherein the univalent cations comprise any one of sodium ions or potassium ions, the bivalent cations comprise any one of calcium ions or magnesium ions or the combination of calcium ions and magnesium ions, the univalent anions comprise any one of chloride ions, nitrate ions, bicarbonate ions or hydroxide ions or the combination of chloride ions, nitrate ions, bicarbonate ions or the combination of hydroxide ions, and the bivalent anions comprise any one of sulfate ions and carbonate ions or the combination of sulfate ions and carbonate ions; in the present embodiment, the hetero salt is composed of sodium ion, calcium ion, magnesium ion, chloride ion, hydroxide ion, carbonate ion, and bicarbonate ion;
2) bipolar membrane electrodialysis separation: 1) after the miscellaneous salt is dissolved, removing carbonate ions and bicarbonate ions in the miscellaneous salt solution to obtain a pre-treatment miscellaneous salt solution, wherein the indexes of the pre-treatment miscellaneous salt solution are as follows: calcium ion concentration < 150mg/L, magnesium ion concentration < 200mg/L, carbonate ion concentration < 50mg/L, bicarbonate ion concentration < 50mg/L, SiO2The concentration is less than 200mg/L, the COD content is less than 200mg/L, and the concentration of heavy metal ions is less than 0.1 mg/L; introducing the pretreated mixed salt solution into a bipolar membrane electrodialysis separation system for acid-base separation, wherein the operating voltage of bipolar membrane electrodialysis is 50V, and the current density is controlled at 1000A/m2Concentration in the alkali chamberThe degree is 6 percent, and the concentration of the acid chamber is 6 percent; separating to obtain liquid alkali, monovalent acid and fresh water; concentrating the liquid caustic soda to a concentration of 10%, then carrying out evaporative crystallization, allowing the liquid caustic soda obtained after the evaporative crystallization to enter a liquid caustic soda storage tank for temporary storage, and recycling water generated in the concentration process to 1) dissolving the miscellaneous salt; the concentration is either evaporation concentration or membrane concentration, and in this embodiment, the concentration is evaporation concentration; if the product required by the customer is solid alkali, the liquid alkali can be dried into the solid alkali by a drying device, and the drying device can be any one of a spray dryer, a paddle dryer, a flash dryer, a pneumatic dryer and a fluidized bed dryer, and in the embodiment, the drying device is a spray dryer.
3) Acid treatment: 2) after the bipolar membrane electrodialysis separation is finished, monovalent monoacid, namely hydrochloric acid is obtained; concentrating the monovalent monoacid to obtain concentrated monovalent monoacid, recycling water obtained in the concentration process to the 1) mixed salt dissolving process, and concentrating to be either evaporation concentration or membrane concentration, wherein in the embodiment, the concentration is evaporation concentration;
4) and (3) electrodialysis concentration: 2) after the bipolar membrane electrodialysis separation is finished, fresh water is conveyed into an electrodialysis concentration system for concentration, and the operation pressure of the electrodialysis concentration is 0.5kg/cm2Operating voltage 100V, current 3A; and separating to obtain electrodialysis concentrated water and electrodialysis produced water, mixing the electrodialysis concentrated water with the miscellaneous salt solution, concentrating the electrodialysis produced water through a membrane, and conveying the electrodialysis produced water into a spray dryer to obtain a dried substance.
Taking 6 tons of miscellaneous salt and dividing the miscellaneous salt into three parts, respectively adopting the embodiment and a conventional miscellaneous salt landfill method and a conventional incineration landfill to treat the three parts of miscellaneous salt, wherein the miscellaneous salt incineration method comprises the steps of treating the miscellaneous salt at high temperature, preheating, decomposing and burning in a secondary combustion chamber, preheating at 300-600 ℃, decomposing at 800-1000 ℃, introducing gas into the secondary combustion chamber, completely oxidizing and decomposing the organic matter into carbon dioxide and water at 1200 ℃, performing oxidative decomposition to convert the organic matter into harmless substances such as water, carbon dioxide and the like, and discharging the residual inorganic salt in a solid waste form. The landfill cost of the miscellaneous salt is 3000 yuan/t, the incineration landfill cost is 3200 yuan/t, the produced byproduct crystalline salt is 300 yuan/t, the byproduct crystalline salt yield, the final miscellaneous salt yield, the miscellaneous salt resource rate, the crystalline salt external sales income, the miscellaneous salt treatment cost and the comprehensive treatment cost in the miscellaneous salt treatment process are counted, and the counting result is shown in table 1.
TABLE 1 statistics of three groups of miscellaneous salt treatment methods
Note: in the table, the cost is negative and represents profit, and the positive represents expenditure.
As can be seen from table 1, the treatment of the embodiment 2 effectively solves the problems that the conventional mixed salt cannot be eliminated and is excessively stacked and accumulated, and the bipolar membrane electrodialysis separation system, the electrodialysis concentration system and the like are utilized, so that the mixed salt which cannot be effectively treated originally is recycled after the treatment of the embodiment, the recycling rate of the mixed salt treatment can reach 95%, and the purposes of harmless and recycling treatment of the mixed salt are really realized; the obtained high-purity liquid caustic soda, sulfuric acid, monovalent monoacid and monovalent mixed acid are subjected to membrane concentration and then are used for self or sold, so that the recycling of mixed salt resources is realized, and the production diversity and income of enterprises are improved; the reuse water obtained by concentration is recycled to the system, so that the utilization rate of water resources is high; meanwhile, as the process equipment used in the embodiment only comprises three types of membranes such as a bipolar membrane electrodialysis separation system, an electrodialysis concentration system and a membrane concentration system, the whole process equipment is operated at normal temperature and normal pressure with low energy consumption, the investment and the operation cost are greatly reduced, and the whole process flow is short, the operation is simple and the operation and maintenance are convenient; the comprehensive overall cost of the treatment of the miscellaneous salt per ton is reduced by 100 percent compared with the operation cost of the traditional process.
Example 3:
the method for recycling mixed salt according to example 1, comprising the steps of:
1) dissolving miscellaneous salt: dissolving miscellaneous salt in water with volume 7 times, stirring and dissolving for 25min at the rotation speed of 900rpm, and stirring to fully dissolve the miscellaneous salt until no solid matter exists, thereby obtaining miscellaneous salt solution; the heterosalt is composed of univalent cations and/or divalent cations, and/or divalent anions, wherein the univalent cations comprise any one or combination of sodium ions or potassium ions, the divalent cations comprise any one or combination of calcium ions or magnesium ions, the univalent anions comprise any one or combination of chloride ions, nitrate ions, bicarbonate ions or hydroxide ions, and the divalent anions comprise any one or combination of sulfate ions and carbonate ions; in the present embodiment, the hetero salt is composed of potassium ion, calcium ion, magnesium ion, nitrate ion, carbonate ion, bicarbonate ion, and hydroxide ion;
2) bipolar membrane electrodialysis separation: 1) after the miscellaneous salt is dissolved, removing carbonate ions and bicarbonate ions in the miscellaneous salt solution to obtain a pre-treatment miscellaneous salt solution, wherein the indexes of the pre-treatment miscellaneous salt solution are as follows: calcium ion concentration < 150mg/L, magnesium ion concentration < 200mg/L, carbonate ion concentration < 50mg/L, bicarbonate ion concentration < 50mg/L, SiO2The concentration is less than 200mg/L, the COD content is less than 200mg/L, and the concentration of heavy metal ions is less than 0.1 mg/L; introducing the pretreated mixed salt solution into a bipolar membrane electrodialysis separation system for acid-base separation, wherein the operating voltage of bipolar membrane electrodialysis is 55V, and the current density is controlled at 900A/m2The concentration of the alkali chamber is 6.5 percent, and the concentration of the acid chamber is 6.5 percent; separating to obtain liquid alkali, mixed acid and fresh water; concentrating the liquid caustic soda to a concentration of 10%, then carrying out evaporative crystallization, allowing the liquid caustic soda obtained after the evaporative crystallization to enter a liquid caustic soda storage tank for temporary storage, and recycling water generated in the concentration process to 1) dissolving the miscellaneous salt; the concentration is either evaporation concentration or membrane concentration, and in this example, the concentration is membrane concentration; if the product required by the customer is solid alkali, the liquid alkali can be dried into the solid alkali by a drying device, and the drying device can be any one of a spray dryer, a paddle dryer, a flash dryer, an air flow dryer and a fluidized bed dryer, and in this embodiment, the drying device is a paddle dryer.
3) Acid treatment: 2) after the bipolar membrane electrodialysis separation is finished, monovalent monoacid, namely nitric acid is obtained; concentrating the monovalent monoacid to obtain concentrated monovalent monoacid, recycling water obtained in the concentration process to the 1) mixed salt dissolving process, and concentrating to be either evaporation concentration or membrane concentration, wherein in the embodiment, the concentration is evaporation concentration;
4) and (3) electrodialysis concentration: 2) after the bipolar membrane electrodialysis separation is finished, fresh water is conveyed into an electrodialysis concentration system for concentration, and the operation pressure of the electrodialysis concentration is 0.5kg/cm2Operating voltage 100V, current 3A; and separating to obtain electrodialysis concentrated water and electrodialysis produced water, mixing the electrodialysis concentrated water with the miscellaneous salt solution, concentrating the electrodialysis produced water through a membrane, and conveying the electrodialysis produced water into a spray dryer to obtain a dried substance.
Taking 6 tons of miscellaneous salt and dividing the miscellaneous salt into three parts, respectively adopting the embodiment and a conventional miscellaneous salt landfill method and a conventional incineration landfill to treat the three parts of miscellaneous salt, wherein the miscellaneous salt incineration method comprises the steps of treating the miscellaneous salt at high temperature, preheating, decomposing and burning in a secondary combustion chamber, preheating at 300-600 ℃, decomposing at 800-1000 ℃, introducing gas into the secondary combustion chamber, completely oxidizing and decomposing the organic matter into carbon dioxide and water at 1200 ℃, performing oxidative decomposition to convert the organic matter into harmless substances such as water, carbon dioxide and the like, and discharging the residual inorganic salt in a solid waste form. The landfill cost of the miscellaneous salt is 3000 yuan/t, the incineration landfill cost is 3200 yuan/t, the produced byproduct crystalline salt is 300 yuan/t according to the average market price, and the byproduct crystalline salt yield, the final miscellaneous salt yield, the miscellaneous salt resource rate, the crystalline salt external sales income, the miscellaneous salt treatment cost and the comprehensive treatment cost in the miscellaneous salt treatment process are counted, and the counting result is shown in table 2.
TABLE 2 statistics of three groups of miscellaneous salt treatment methods
Note: in the table, the cost is negative and represents profit, and the positive represents expenditure.
As can be seen from table 2, the treatment of the embodiment 3 effectively solves the problems that the conventional mixed salt cannot be eliminated and is excessively stacked and accumulated, and the bipolar membrane electrodialysis separation system, the electrodialysis concentration system and the like are utilized, so that the mixed salt which cannot be effectively treated originally is recycled after the treatment of the embodiment, the recycling rate of the mixed salt treatment can reach 89%, and the purposes of harmless and recycling treatment of the mixed salt are really realized; the obtained high-purity liquid caustic soda, sulfuric acid, monovalent monoacid and monovalent mixed acid are subjected to membrane concentration and then are used for self or sold, so that the recycling of mixed salt resources is realized, and the production diversity and income of enterprises are improved; the reuse water obtained by concentration is recycled to the system, so that the utilization rate of water resources is high; meanwhile, as the process equipment used in the embodiment only comprises three types of membranes such as a bipolar membrane electrodialysis separation system, an electrodialysis concentration system and a membrane concentration system, the whole process equipment is operated at normal temperature and normal pressure with low energy consumption, the investment and the operation cost are greatly reduced, and the whole process flow is short, the operation is simple and the operation and maintenance are convenient; the comprehensive overall cost of the treatment of the miscellaneous salt per ton is reduced by 96 percent compared with the operation cost of the traditional process.
Example 4:
the method for recycling mixed salt according to example 1, comprising the steps of:
1) dissolving miscellaneous salt: dissolving miscellaneous salt in water with volume of 9 times, stirring and dissolving for 40min at the rotation speed of 800rpm, and stirring to fully dissolve the miscellaneous salt until no solid matter exists, thereby obtaining miscellaneous salt solution; the heterosalt is composed of univalent cations and/or divalent cations, and/or divalent anions, wherein the univalent cations comprise any one or combination of sodium ions or potassium ions, the divalent cations comprise any one or combination of calcium ions or magnesium ions, the univalent anions comprise any one or combination of chloride ions, nitrate ions, bicarbonate ions or hydroxide ions, and the divalent anions comprise any one or combination of sulfate ions and carbonate ions; in the present embodiment, the hetero salt is composed of sodium ion, calcium ion, magnesium ion, sulfate ion, carbonate ion, and bicarbonate ion;
2) bipolar membrane electrodialysis separation: 1) after the miscellaneous salt is dissolved, removing carbonate ions and bicarbonate ions in the miscellaneous salt solution to obtain a pre-treatment miscellaneous salt solution, wherein the indexes of the pre-treatment miscellaneous salt solution are as follows: calcium ion concentration < 150mg/L, magnesium ion concentration < 200mg/L, carbonate ion concentration < 50mg/L, bicarbonate ion concentration < 50mg/L, SiO2The concentration is less than 200mg/L, the COD content is less than 200mg/L, and the concentration of heavy metal ions is less than 0.1 mg/L; introducing the pretreated mixed salt solution into a bipolar membrane electrodialysis separation system for acid-base separation, wherein the operating voltage of bipolar membrane electrodialysis is 60V, and the current density is controlled at 800A/m2The concentration of the alkali chamber is 7 percent, and the concentration of the acid chamber is 7 percent; separating to obtain liquid alkali, mixed acid and fresh water; concentrating the liquid caustic soda to a concentration of 13%, then carrying out evaporative crystallization, allowing the liquid caustic soda obtained after the evaporative crystallization to enter a liquid caustic soda storage tank for temporary storage, and recycling water generated in the concentration process to 1) dissolving the miscellaneous salt; the concentration is either evaporation concentration or membrane concentration, and in this embodiment, the concentration is evaporation concentration; if the product required by the customer is solid alkali, the liquid alkali can be dried into the solid alkali by drying equipment, and the drying equipment can be any one of a spray dryer, a paddle dryer, a flash evaporation dryer, an air flow dryer and a fluidized bed dryer; in this embodiment, the drying apparatus is a flash dryer.
3) Acid treatment: 2) after the bipolar membrane electrodialysis separation is completed, sulfuric acid is obtained, concentrated sulfuric acid with the concentration of 15% is obtained through concentration, water obtained in the concentration process is recycled to the 1) mixed salt dissolving process, and is concentrated into any one of evaporation concentration or membrane concentration, and in the embodiment, the concentration is evaporation concentration;
4) and (3) electrodialysis concentration: 2) after the bipolar membrane electrodialysis separation is finished, fresh water is conveyed into an electrodialysis concentration system for concentration, and the operation pressure of the electrodialysis concentration is 1.0kg/cm2The operating voltage is 150V, and the current is 2.5A; and separating to obtain electrodialysis concentrated water and electrodialysis produced water, mixing the electrodialysis concentrated water with the miscellaneous salt solution, concentrating the electrodialysis produced water through a membrane, and conveying the electrodialysis produced water into a spray dryer to obtain a dried substance.
Taking 6 tons of miscellaneous salt and dividing the miscellaneous salt into three parts, respectively adopting the embodiment and a conventional miscellaneous salt landfill method and a conventional incineration landfill to treat the three parts of miscellaneous salt, wherein the miscellaneous salt incineration method comprises the steps of treating the miscellaneous salt at high temperature, preheating, decomposing and burning in a secondary combustion chamber, preheating at 300-600 ℃, decomposing at 800-1000 ℃, introducing gas into the secondary combustion chamber, completely oxidizing and decomposing the organic matter into carbon dioxide and water at 1200 ℃, performing oxidative decomposition to convert the organic matter into harmless substances such as water, carbon dioxide and the like, and discharging the residual inorganic salt in a solid waste form. The landfill cost of the miscellaneous salt is 3000 yuan/t, the incineration landfill cost is 3200 yuan/t, the produced byproduct crystalline salt is 300 yuan/t, the byproduct crystalline salt yield, the final miscellaneous salt yield, the miscellaneous salt resource rate, the crystalline salt external sales income, the miscellaneous salt treatment cost and the comprehensive treatment cost in the miscellaneous salt treatment process are counted, and the counting result is shown in table 3.
TABLE 3 statistics of three groups of miscellaneous salt treatment methods
| Item | Example 4 | Landfill treatment | Incineration landfill |
| Final miscellaneous salt yield (t) | 0.16 | 2 | 0.5 |
| Recycling ratio of miscellaneous salt (%) | 92％ | 0 | 0 |
| Liquid caustic soda and sulfuric acid sale income (yuan) | -252 | 0 | 0 |
| Miscellaneous salt treatment cost (Yuan) | +480 | +3000 | +3200 |
| Total cost (Yuan) | +228 | +3000 | +3200 |
Note: in the table, the cost is negative and represents profit, and the positive represents expenditure.
As can be seen from table 3, the treatment of the embodiment 4 effectively solves the problems that the conventional mixed salt cannot be eliminated and is excessively stacked and accumulated, and the bipolar membrane electrodialysis separation system, the electrodialysis concentration system and the like are utilized, so that the mixed salt which cannot be effectively treated originally is recycled after the treatment of the embodiment, the recycling rate of the mixed salt treatment can reach 92%, and the purposes of harmless and recycling treatment of the mixed salt are really realized; the obtained high-purity liquid caustic soda, sulfuric acid, monovalent monoacid and monovalent mixed acid are subjected to membrane concentration and then are used for self or sold, so that the recycling of mixed salt resources is realized, and the production diversity and income of enterprises are improved; the reuse water obtained by concentration is recycled to the system, so that the utilization rate of water resources is high; meanwhile, as the process equipment used in the embodiment only comprises three types of membranes such as a bipolar membrane electrodialysis separation system, an electrodialysis concentration system and a membrane concentration system, the whole process equipment is operated at normal temperature and normal pressure with low energy consumption, the investment and the operation cost are greatly reduced, and the whole process flow is short, the operation is simple and the operation and maintenance are convenient; the comprehensive overall cost of treating the miscellaneous salt per ton is reduced by 92 percent compared with the operation cost of the traditional process.
Example 5:
the method for recycling mixed salt according to example 1, comprising the steps of:
1) dissolving miscellaneous salt: dissolving miscellaneous salt in water with volume of 11 times, stirring and dissolving for 60min under the condition that the rotating speed is 700rpm, and stirring to fully dissolve the miscellaneous salt until no solid matter exists, so as to obtain miscellaneous salt solution; the heterosalt is composed of univalent cations and/or divalent cations, and/or divalent anions, wherein the univalent cations comprise any one or combination of sodium ions or potassium ions, the divalent cations comprise any one or combination of calcium ions or magnesium ions, the univalent anions comprise any one or combination of chloride ions, nitrate ions, bicarbonate ions or hydroxide ions, and the divalent anions comprise any one or combination of sulfate ions and carbonate ions; in this example, the hetero salt is composed of potassium ion, calcium ion, magnesium ion, nitrate ion, and sulfate group;
2) bipolar membrane electrodialysis separation: 1) after the miscellaneous salt is dissolved, removing carbonate ions and bicarbonate ions in the miscellaneous salt solution to obtain a pre-treatment miscellaneous salt solution, wherein the indexes of the pre-treatment miscellaneous salt solution are as follows: calcium ion concentration < 150mg/L, magnesium ion concentration < 200mg/L, carbonate ion concentration < 50mg/L, bicarbonate ion concentration < 50mg/L, SiO2The concentration is less than 200mg/L, the COD content is less than 200mg/L, and the concentration of heavy metal ions is less than 0.1 mg/L; introducing the pretreated mixed salt solution into a bipolar membrane electrodialysis separation system for acid-base separation, wherein the operating voltage of bipolar membrane electrodialysis is 65V, and the current density is controlled at 700A/m2The concentration of the alkali chamber is 7.5 percent, and the concentration of the acid chamber is 7 percent; separating to obtain liquid alkali, mixed acid and fresh water; concentrating the liquid caustic soda to a concentration of 15%, then carrying out evaporative crystallization, allowing the liquid caustic soda obtained after the evaporative crystallization to enter a liquid caustic soda storage tank for temporary storage, and recycling water generated in the concentration process to 1) dissolving the miscellaneous salt; the concentration is either evaporation concentration or membrane concentration, and in this embodiment, the concentration is evaporation concentration; if the product required by the customer is a solid base, thenThe liquid alkali can be dried into solid alkali by drying equipment, and the drying equipment can be any one of a spray dryer, a paddle dryer, a flash evaporation dryer, an air flow dryer and a fluidized bed dryer; in this embodiment, the drying apparatus is a pneumatic dryer.
3) Acid treatment: 2) after the bipolar membrane electrodialysis separation is finished, conveying the mixed acid into a nanofiltration membrane system for separation, wherein the rejection rate of sulfate ions of the nanofiltration membrane system is more than or equal to 99%, and separating to obtain monovalent monoacid and sulfuric acid, wherein the monovalent monoacid is nitric acid; concentrating the monovalent monoacid to obtain concentrated monovalent monoacid, recycling water obtained in the concentration process to the 1) mixed salt dissolving, and concentrating into any one of evaporation concentration or membrane concentration, wherein the concentration is membrane concentration in the embodiment; concentrating sulfuric acid to obtain concentrated sulfuric acid with the concentration of 10%, recycling water obtained in the concentration process to the 1) mixed salt dissolving, and concentrating the water to be either evaporation concentration or membrane concentration, wherein the concentration is membrane concentration in the embodiment;
4) and (3) electrodialysis concentration: 2) after the bipolar membrane electrodialysis separation is finished, fresh water is conveyed into an electrodialysis concentration system for concentration, and the operation pressure of the electrodialysis concentration is 1.0kg/cm2The operating voltage is 150V, and the current is 2.5A; and separating to obtain electrodialysis concentrated water and electrodialysis produced water, mixing the electrodialysis concentrated water with the miscellaneous salt solution, and conveying the electrodialysis produced water into a spray dryer to obtain a dried substance.
Taking 6 tons of miscellaneous salt and dividing the miscellaneous salt into three parts, respectively adopting the embodiment and a conventional miscellaneous salt landfill method and a conventional incineration landfill to treat the three parts of miscellaneous salt, wherein the miscellaneous salt incineration method comprises the steps of treating the miscellaneous salt at high temperature, preheating, decomposing and burning in a secondary combustion chamber, preheating at 300-600 ℃, decomposing at 800-1000 ℃, introducing gas into the secondary combustion chamber, completely oxidizing and decomposing the organic matter into carbon dioxide and water at 1200 ℃, performing oxidative decomposition to convert the organic matter into harmless substances such as water, carbon dioxide and the like, and discharging the residual inorganic salt in a solid waste form. The landfill cost of the miscellaneous salt is 3000 yuan/t, the incineration landfill cost is 3200 yuan/t, the produced byproduct crystalline salt is 1000 yuan/t according to the average market price, and the byproduct crystalline salt yield, the final miscellaneous salt yield, the miscellaneous salt resource rate, the crystalline salt external sales income, the miscellaneous salt treatment cost and the comprehensive treatment cost in the miscellaneous salt treatment process are counted, and the counting result is shown in table 4.
TABLE 4 statistics of three groups of miscellaneous salt treatment methods
Note: in the table, the cost is negative and represents profit, and the positive represents expenditure.
As can be seen from table 4, the treatment of the example 5 effectively solves the problems that the conventional mixed salt cannot be eliminated and is excessively stacked and accumulated, and the bipolar membrane electrodialysis separation system, the electrodialysis concentration system and the like are utilized, so that the mixed salt which cannot be effectively treated originally is recycled after the treatment of the embodiment, the recycling rate of the mixed salt treatment can reach 90%, and the purposes of harmless and recycling treatment of the mixed salt are really realized; the obtained high-purity liquid caustic soda, sulfuric acid, monovalent monoacid and monovalent mixed acid are subjected to membrane concentration and then are used for self or sold, so that the recycling of mixed salt resources is realized, and the production diversity and income of enterprises are improved; the reuse water obtained by concentration is recycled to the system, so that the utilization rate of water resources is high; meanwhile, as the process equipment used in the embodiment only comprises three types of membranes such as a bipolar membrane electrodialysis separation system, an electrodialysis concentration system and a membrane concentration system, the whole process equipment is operated at normal temperature and normal pressure with low energy consumption, the investment and the operation cost are greatly reduced, and the whole process flow is short, the operation is simple and the operation and maintenance are convenient; the comprehensive overall cost of the treatment of the miscellaneous salt per ton is reduced by 98 percent compared with the operation cost of the traditional process.
Example 6:
the method for recycling mixed salt according to example 1, comprising the steps of:
1) dissolving miscellaneous salt: dissolving miscellaneous salt in 13 times of water, stirring and dissolving for 70min at the rotation speed of 600rpm, and stirring to fully dissolve the miscellaneous salt until no solid matter exists, thereby obtaining miscellaneous salt solution; the heterosalt is composed of univalent cations and/or divalent cations, and/or divalent anions, wherein the univalent cations comprise any one or combination of sodium ions or potassium ions, the divalent cations comprise any one or combination of calcium ions or magnesium ions, the univalent anions comprise any one or combination of chloride ions, nitrate ions, bicarbonate ions or hydroxide ions, and the divalent anions comprise any one or combination of sulfate ions and carbonate ions; in the present embodiment, the hetero salt is composed of sodium ion, calcium ion, magnesium ion, chloride ion, sulfate ion, hydroxide ion, and bicarbonate ion;
2) bipolar membrane electrodialysis separation: 1) after the miscellaneous salt is dissolved, removing carbonate ions and bicarbonate ions in the miscellaneous salt solution to obtain a pre-treatment miscellaneous salt solution, wherein the indexes of the pre-treatment miscellaneous salt solution are as follows: calcium ion concentration < 150mg/L, magnesium ion concentration < 200mg/L, carbonate ion concentration < 50mg/L, bicarbonate ion concentration < 50mg/L, SiO2The concentration is less than 200mg/L, the COD content is less than 200mg/L, and the concentration of heavy metal ions is less than 0.1 mg/L; introducing the pretreated mixed salt solution into a bipolar membrane electrodialysis separation system for acid-base separation, wherein the operating voltage of bipolar membrane electrodialysis is 70V, and the current density is controlled at 600A/m2The concentration of the alkali chamber is 8 percent, and the concentration of the acid chamber is 7.5 percent; separating to obtain liquid alkali, mixed acid and fresh water; concentrating the liquid caustic soda to a concentration of 18%, then carrying out evaporative crystallization, allowing the liquid caustic soda obtained after the evaporative crystallization to enter a liquid caustic soda storage tank for temporary storage, and recycling water generated in the concentration process to 1) dissolving the miscellaneous salt; the concentration is either evaporation concentration or membrane concentration, and in this embodiment, the concentration is evaporation concentration; if the product required by the customer is solid alkali, the liquid alkali can be dried into the solid alkali by drying equipment, and the drying equipment can be any one of a spray dryer, a paddle dryer, a flash evaporation dryer, an air flow dryer and a fluidized bed dryer; in this embodiment, the drying apparatus is a fluidized bed dryer.
3) Acid treatment: 2) after the bipolar membrane electrodialysis separation is finished, conveying the mixed acid into a nanofiltration membrane system for separation, wherein the rejection rate of sulfate ions of the nanofiltration membrane system is more than or equal to 99%, and separating to obtain monovalent monoacid and sulfuric acid, wherein the monovalent monoacid is hydrochloric acid; concentrating the monovalent monoacid to obtain concentrated monovalent monoacid, recycling water obtained in the concentration process to the 1) mixed salt dissolving process, and concentrating to be either evaporation concentration or membrane concentration, wherein in the embodiment, the concentration is evaporation concentration; concentrating sulfuric acid to obtain concentrated sulfuric acid with the concentration of 30%, recycling water obtained in the concentration process to the 1) mixed salt dissolving, and concentrating the water to be either evaporation concentration or membrane concentration, wherein the concentration is evaporation concentration in the embodiment;
4) and (3) electrodialysis concentration: 2) after the bipolar membrane electrodialysis separation is finished, fresh water is conveyed into an electrodialysis concentration system for concentration, and the operation pressure of the electrodialysis concentration is 1.5kg/cm2The operating voltage is 170V, and the current is 2.3A; and separating to obtain electrodialysis concentrated water and electrodialysis produced water, mixing the electrodialysis concentrated water with the miscellaneous salt solution, concentrating the electrodialysis produced water through a membrane, and conveying the electrodialysis produced water into a spray dryer to obtain a dried substance.
Taking 6 tons of miscellaneous salt and dividing the miscellaneous salt into three parts, respectively adopting the embodiment and a conventional miscellaneous salt landfill method and a conventional incineration landfill to treat the three parts of miscellaneous salt, wherein the miscellaneous salt incineration method comprises the steps of treating the miscellaneous salt at high temperature, preheating, decomposing and burning in a secondary combustion chamber, preheating at 300-600 ℃, decomposing at 800-1000 ℃, introducing gas into the secondary combustion chamber, completely oxidizing and decomposing the organic matter into carbon dioxide and water at 1200 ℃, performing oxidative decomposition to convert the organic matter into harmless substances such as water, carbon dioxide and the like, and discharging the residual inorganic salt in a solid waste form. The landfill cost of the miscellaneous salt is 3000 yuan/t, the incineration landfill cost is 3200 yuan/t, the produced byproduct crystalline salt is 1000 yuan/t according to the average market price, and the byproduct crystalline salt yield, the final miscellaneous salt yield, the miscellaneous salt resource rate, the crystalline salt external sales income, the miscellaneous salt treatment cost and the comprehensive treatment cost in the miscellaneous salt treatment process are counted, and the counting result is shown in table 5.
TABLE 5 statistics of three groups of miscellaneous salt treatment methods
Note: in the table, the cost is negative and represents profit, and the positive represents expenditure.
As can be seen from table 5, the treatment of the example 6 effectively solves the problems that the conventional mixed salt cannot be eliminated and is excessively stacked and accumulated, and the bipolar membrane electrodialysis separation system, the electrodialysis concentration system and the like are utilized, so that the mixed salt which cannot be effectively treated originally is recycled after the treatment of the present embodiment, the recycling rate of the mixed salt treatment can reach 93%, and the purposes of harmless and recycling treatment of the mixed salt are really realized; the obtained high-purity liquid caustic soda, sulfuric acid, monovalent monoacid and monovalent mixed acid are subjected to membrane concentration and then are used for self or sold, so that the recycling of mixed salt resources is realized, and the production diversity and income of enterprises are improved; the reuse water obtained by concentration is recycled to the system, so that the utilization rate of water resources is high; meanwhile, as the process equipment used in the embodiment only comprises three types of membranes such as a bipolar membrane electrodialysis separation system, an electrodialysis concentration system and a membrane concentration system, the whole process equipment is operated at normal temperature and normal pressure with low energy consumption, the investment and the operation cost are greatly reduced, and the whole process flow is short, the operation is simple and the operation and maintenance are convenient; the comprehensive overall cost of the treatment of the miscellaneous salt per ton is reduced by 100 percent compared with the operation cost of the traditional process.
Example 7:
the method for recycling mixed salt according to example 1, comprising the steps of:
1) dissolving miscellaneous salt: dissolving the mixed salt in water with the volume of 20 times, stirring and dissolving for 120min under the condition that the rotating speed is 300rpm, and stirring to fully dissolve the mixed salt until no solid matter exists, so as to obtain mixed salt liquid; the heterosalt is composed of univalent cations and/or divalent cations, and/or divalent anions, wherein the univalent cations comprise any one or combination of sodium ions or potassium ions, the divalent cations comprise any one or combination of calcium ions or magnesium ions, the univalent anions comprise any one or combination of chloride ions, nitrate ions, bicarbonate ions or hydroxide ions, and the divalent anions comprise any one or combination of sulfate ions and carbonate ions; in the present embodiment, the hetero salt is composed of potassium ion, calcium ion, magnesium ion, chloride ion, nitrate ion, sulfate ion, carbonate ion, bicarbonate ion, and hydroxide ion;
2) bipolar membrane electrodialysis separation: 1) after the miscellaneous salt is dissolved, removing carbonate ions and bicarbonate ions in the miscellaneous salt solution to obtain a pre-treatment miscellaneous salt solution, wherein the indexes of the pre-treatment miscellaneous salt solution are as follows: calcium ion concentration < 150mg/L, magnesium ion concentration < 200mg/L, carbonate ion concentration < 50mg/L, bicarbonate ion concentration < 50mg/L, SiO2The concentration is less than 200mg/L, the COD content is less than 200mg/L, and the concentration of heavy metal ions is less than 0.1 mg/L; introducing the pretreated mixed salt solution into a bipolar membrane electrodialysis separation system for acid-base separation, wherein the operating voltage of bipolar membrane electrodialysis is 100V, and the current density is controlled at 200A/m2The concentration of the alkali chamber is 9 percent, and the concentration of the acid chamber is 8 percent; separating to obtain liquid alkali, mixed acid and fresh water; concentrating the liquid caustic soda to a concentration of 30%, then carrying out evaporative crystallization, allowing the liquid caustic soda obtained after the evaporative crystallization to enter a liquid caustic soda storage tank for temporary storage, and recycling water generated in the concentration process to 1) dissolving the miscellaneous salt; the concentration is either evaporation concentration or membrane concentration, and in this embodiment, the concentration is evaporation concentration; if the product required by the customer is solid alkali, the liquid alkali can be dried into the solid alkali by drying equipment, and the drying equipment can be any one of a spray dryer, a paddle dryer, a flash evaporation dryer, an air flow dryer and a fluidized bed dryer; in this embodiment, the drying apparatus is a spray dryer.
3) Acid treatment: 2) after the bipolar membrane electrodialysis separation is finished, conveying the mixed acid into a nanofiltration membrane system for separation, wherein the rejection rate of sulfate ions of the nanofiltration membrane system is more than or equal to 99%, and separating to obtain monovalent mixed acid and sulfuric acid; concentrating the monovalent mixed acid to obtain concentrated monovalent mixed acid, recycling water obtained in the concentration process to the dissolution of the mixed salt in the step 1), and concentrating the monovalent mixed acid into any one of evaporation concentration or membrane concentration, wherein the concentration is the evaporation concentration in the embodiment; concentrating sulfuric acid to obtain concentrated sulfuric acid with concentration of 50%, recycling water obtained in the concentration process to the 1) mixed salt dissolving, and concentrating to be either evaporation concentration or membrane concentration, wherein in the embodiment, the concentration is evaporation concentration;
4) and (3) electrodialysis concentration: 2) after the bipolar membrane electrodialysis separation is finished, fresh water is conveyed into an electrodialysis concentration system for concentration, and the operation pressure of the electrodialysis concentration is 3.0kg/cm2Operating voltage 250V, current 3A; and separating to obtain electrodialysis concentrated water and electrodialysis produced water, mixing the electrodialysis concentrated water with the miscellaneous salt solution, concentrating the electrodialysis produced water through a membrane, and conveying the electrodialysis produced water into a spray dryer to obtain a dried substance.
Taking 6 tons of miscellaneous salt and dividing the miscellaneous salt into three parts, respectively adopting the embodiment and a conventional miscellaneous salt landfill method and a conventional incineration landfill to treat the three parts of miscellaneous salt, wherein the miscellaneous salt incineration method comprises the steps of treating the miscellaneous salt at high temperature, preheating, decomposing and burning in a secondary combustion chamber, preheating at 300-600 ℃, decomposing at 800-1000 ℃, introducing gas into the secondary combustion chamber, completely oxidizing and decomposing the organic matter into carbon dioxide and water at 1200 ℃, performing oxidative decomposition to convert the organic matter into harmless substances such as water, carbon dioxide and the like, and discharging the residual inorganic salt in a solid waste form. The landfill cost of the miscellaneous salt is 3000 yuan/t, the incineration landfill cost is 3200 yuan/t, the produced byproduct crystalline salt is 300 yuan/t, the byproduct crystalline salt yield, the final miscellaneous salt yield, the miscellaneous salt resource rate, the crystalline salt external sales income, the miscellaneous salt treatment cost and the comprehensive treatment cost in the miscellaneous salt treatment process are counted, and the counting result is shown in table 6.
TABLE 6 statistics of three groups of miscellaneous salt treatment methods
| Item | Example 9 | Landfill treatment | Incineration landfill |
| Final miscellaneous salt yield (t) | 0.4 | 2 | 0.5 |
| Recycling ratio of miscellaneous salt (%) | 80％ | 0 | 0 |
| Liquid caustic soda, sulfuric acid and monovalent mixed acid for sale | -480 | 0 | 0 |
| Miscellaneous salt treatment cost (Yuan) | +1200 | +3000 | +3200 |
| Total cost (Yuan) | +720 | +3000 | +3200 |
Note: in the table, the cost is negative and represents profit, and the positive represents expenditure.
As can be seen from table 6, the treatment of the example 7 effectively solves the problems that the conventional mixed salt cannot be eliminated and is excessively stacked and accumulated, and the bipolar membrane electrodialysis separation system, the electrodialysis concentration system and the like are utilized, so that the mixed salt which cannot be effectively treated originally is recycled after the treatment of the embodiment, the recycling rate of the mixed salt treatment can reach 80%, and the purposes of harmless and recycling treatment of the mixed salt are really realized; the obtained high-purity liquid caustic soda, sulfuric acid, monovalent monoacid and monovalent mixed acid are subjected to membrane concentration and then are used for self or sold, so that the recycling of mixed salt resources is realized, and the production diversity and income of enterprises are improved; the reuse water obtained by concentration is recycled to the system, so that the utilization rate of water resources is high; meanwhile, as the process equipment used in the embodiment only comprises three types of membranes such as a bipolar membrane electrodialysis separation system, an electrodialysis concentration system and a membrane concentration system, the whole process equipment is operated at normal temperature and normal pressure with low energy consumption, the investment and the operation cost are greatly reduced, and the whole process flow is short, the operation is simple and the operation and maintenance are convenient; the comprehensive overall cost of the treatment of the miscellaneous salt per ton is reduced by 76 percent compared with the operation cost of the traditional process.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (20)
1. The method for recycling mixed salt is characterized by comprising the following steps:
1) dissolving miscellaneous salt: dissolving miscellaneous salt in water with the volume of 5-20 times, and stirring to fully dissolve the miscellaneous salt until no solid matter exists, so as to obtain miscellaneous salt liquid; the hetero salt is composed of univalent cations and/or bivalent cations, the univalent anions and/or bivalent anions, the univalent cations comprise any one of sodium ions or potassium ions, the bivalent cations comprise any one of calcium ions or magnesium ions or the combination of calcium ions and magnesium ions, the univalent anions comprise any one of chloride ions, nitrate ions, bicarbonate ions or hydroxide ions or the combination of chloride ions, nitrate ions, bicarbonate ions or the combination of hydroxide ions, and the bivalent anions comprise any one of sulfate ions and carbonate ions or the combination of sulfate ions and carbonate ions;
2) bipolar membrane electrodialysis separation: after the 1) mixed salt is dissolved, removing carbonate ions and bicarbonate ions in the mixed salt solution to obtain a pretreated mixed salt solution; subjecting the pre-treatmentIntroducing the complex salt solution into a bipolar membrane electrodialysis separation system for acid-base separation, wherein the operating voltage of bipolar membrane electrodialysis is 50-100V, and the current density is controlled to be 200-1000A/m2The concentration of the alkali chamber is 6 to 9 percent, and the concentration of the acid chamber is 6 to 8 percent; separating to obtain liquid alkali, acid and fresh water;
3) acid treatment: after the bipolar membrane electrodialysis separation is finished, if the acid comprises monovalent acid and divalent acid, conveying the acid into a nanofiltration membrane system for separation, wherein the retention rate of sulfate ions of the nanofiltration membrane system is more than or equal to 98%, and separating to obtain monovalent monoacid or monovalent mixed acid and sulfuric acid; if the acid only comprises the monovalent acid or the divalent acid, the acid is not separated to obtain any one of monovalent monoacid, monovalent mixed acid or sulfuric acid;
4) and (3) electrodialysis concentration: and 2) after the bipolar membrane electrodialysis separation is finished, conveying the fresh water into an electrodialysis concentration system for concentration, wherein the operation pressure of the electrodialysis concentration is 0.5-3.0 kg/cm2The operating voltage is 100-250V, and the current is 1-3A; and separating to obtain electrodialysis concentrated water and electrodialysis produced water, mixing the electrodialysis concentrated water with the miscellaneous salt solution, and conveying the electrodialysis produced water into a spray dryer to obtain a dried substance.
2. The method for recycling mixed salt according to claim 1, wherein the 1) mixed salt dissolution specifically comprises: and mixing the mixed salt with water, stirring and dissolving for 10-120 min under the condition that the rotating speed is 300-1000 rpm so as to fully dissolve the mixed salt, and obtaining the mixed salt solution after stirring.
3. The method for recycling mixed salt according to any one of claims 1 or 2, wherein in the 2) bipolar membrane electrodialysis separation, the pretreated mixed salt solution is subjected to removal of suspended matters, particulate matters, hardness, colloids and silica, and finally the indexes of the mixed salt solution are as follows: calcium ion concentration < 150mg/L, magnesium ion concentration < 200mg/L, carbonate ion concentration < 50mg/L, bicarbonate ion concentration < 50mg/L, SiO2The concentration is less than 200mg/L, the COD content is less than 200mg/L, and the total concentration of heavy metal ions isThe degree is less than 0.1 mg/L.
4. The method as claimed in claim 1 or 2, wherein in the step 4) of electrodialysis concentration, the electrodialysis water is concentrated by a membrane and then delivered to the spray dryer.
5. The method as claimed in claim 3, wherein in the step 4) of electrodialysis concentration, the electrodialysis water is concentrated by a membrane and then delivered to the spray dryer.
6. The method for recycling mixed salt according to any one of claims 1, 2 and 5, wherein the liquid alkali obtained in the 2) bipolar membrane electrodialysis separation is concentrated to obtain concentrated liquid alkali; the 3) acid-treating the obtained monovalent mono-acid, the monovalent mixed acid, the sulfuric acid, the monovalent mono-acid and the sulfuric acid, or the monovalent mixed acid and the sulfuric acid, concentrating, if the concentration object is the monovalent mono-acid and the sulfuric acid or the monovalent mixed acid and the sulfuric acid, respectively and independently concentrating the monovalent mono-acid and the sulfuric acid, or the monovalent mixed acid and the sulfuric acid; and (3) recycling water obtained in the concentration process to the dissolution of the mixed salt in the step 1).
7. The method for recycling mixed salt according to claim 3, wherein the liquid alkali obtained in the 2) bipolar membrane electrodialysis separation is concentrated to obtain concentrated liquid alkali; the 3) acid-treating the obtained monovalent mono-acid, the monovalent mixed acid, the sulfuric acid, the monovalent mono-acid and the sulfuric acid, or the monovalent mixed acid and the sulfuric acid, concentrating, if the concentration object is the monovalent mono-acid and the sulfuric acid or the monovalent mixed acid and the sulfuric acid, respectively and independently concentrating the monovalent mono-acid and the sulfuric acid, or the monovalent mixed acid and the sulfuric acid; and (3) recycling water obtained in the concentration process to the dissolution of the mixed salt in the step 1).
8. The method for recycling mixed salt according to claim 4, wherein the liquid alkali obtained in the 2) bipolar membrane electrodialysis separation is concentrated to obtain concentrated liquid alkali; the 3) acid-treating the obtained monovalent mono-acid, the monovalent mixed acid, the sulfuric acid, the monovalent mono-acid and the sulfuric acid, or the monovalent mixed acid and the sulfuric acid, concentrating, if the concentration object is the monovalent mono-acid and the sulfuric acid or the monovalent mixed acid and the sulfuric acid, respectively and independently concentrating the monovalent mono-acid and the sulfuric acid, or the monovalent mixed acid and the sulfuric acid; and (3) recycling water obtained in the concentration process to the dissolution of the mixed salt in the step 1).
9. A method as claimed in claim 6, wherein the concentration is membrane concentration or evaporation concentration.
10. A method as claimed in any one of claims 7 to 8, wherein the concentration is membrane concentration or evaporation concentration.
11. The mixed salt recycling treatment system is characterized by comprising a dissolving tank, a reuse water tank, a bipolar membrane electrodialysis separation system and an electrodialysis concentration system, wherein a solid inlet of the dissolving tank is connected with an outlet of a mixed salt bin, a liquid inlet of the dissolving tank is connected with an outlet of the reuse water tank, an outlet of the dissolving tank is connected with an inlet of a carbon remover, and an outlet of the carbon remover is connected with an inlet of the bipolar membrane electrodialysis separation system; the liquid alkali outlet of the bipolar membrane electrodialysis separation system is connected with the inlet of the liquid alkali storage tank, and the acid outlet of the bipolar membrane electrodialysis separation system is connected with the inlet of the nanofiltration membrane system; a concentrated water outlet of the nanofiltration membrane system is connected with an inlet of a sulfuric acid storage tank, and a water production outlet of the nanofiltration membrane system is connected with an inlet of a monovalent acid storage tank; the acid outlet of the bipolar membrane electrodialysis separation system is also connected with the inlet of the monovalent acid storage tank through a first overrunning pipeline, and the acid outlet of the bipolar membrane electrodialysis separation system is also connected with the inlet of the sulfuric acid storage tank through a second overrunning pipeline; the fresh water outlet of the bipolar membrane electrodialysis separation system is connected with the inlet of the electrodialysis concentration system, the water production outlet of the electrodialysis concentration system is connected with the inlet of the spray dryer, and the concentrated water outlet of the electrodialysis concentration system is connected with the inlet of the reuse water pool.
12. A miscellaneous salt recycling treatment system as claimed in claim 11, wherein a stirrer is provided in the dissolution tank.
13. The system for recycling the mixed salt according to any one of claims 11 or 12, further comprising a mixed salt pretreatment system, wherein an inlet of the pretreatment system is connected with an outlet of the mixed salt dissolving tank, and an outlet of the pretreatment system is connected with an inlet of the bipolar membrane electrodialysis separation system; the pretreatment system comprises a high-density sedimentation tank, an immersed ultrafiltration, ion exchange resin and a carbon remover, wherein an outlet of a dissolving tank is connected with an inlet of the high-density sedimentation tank, an outlet of the high-density sedimentation tank is connected with an inlet of the immersed ultrafiltration membrane, an outlet of the immersed ultrafiltration membrane is connected with an inlet of the ion exchange resin, an outlet of the ion exchange resin is connected with an inlet of the carbon remover, and an outlet of the carbon remover is connected with an inlet of the bipolar membrane electrodialysis separation system.
14. The mixed salt recycling treatment system according to any one of claims 11 or 12, further comprising a deep concentration system, wherein the deep concentration system comprises a liquid caustic soda deep concentration system, a sulfuric acid deep concentration system and an acid deep concentration system, a liquid caustic outlet of the bipolar membrane electrodialysis separation system is connected with an inlet of the liquid caustic soda deep concentration system, and a concentrated water outlet of the liquid caustic deep concentration system is connected with the liquid caustic soda storage tank; a concentrated water outlet of the nanofiltration membrane system is connected with an inlet of the sulfuric acid deep concentration system through the second overrunning pipeline, and a concentrated water outlet of the sulfuric acid deep concentration system is connected with the sulfuric acid storage tank; a water production outlet of the nanofiltration membrane system is connected with an inlet of the acid deep concentration system through the first overrunning pipeline, and a concentrated water outlet of the acid deep concentration system is connected with the monovalent acid storage tank; and the water production outlet of the liquid caustic soda deep concentration system, the water production outlet of the sulfuric acid deep concentration system and the water production outlet of the acid deep concentration system are all connected with the inlet of the reuse water pool.
15. The system for recycling mixed salt as claimed in claim 13, wherein the system further comprises a deep concentration system, the deep concentration system comprises a liquid alkali deep concentration system, a sulfuric acid deep concentration system and an acid deep concentration system, the liquid alkali outlet of the bipolar membrane electrodialysis separation system is connected with the inlet of the liquid alkali deep concentration system, and the concentrated water outlet of the liquid alkali deep concentration system is connected with the liquid alkali storage tank; a concentrated water outlet of the nanofiltration membrane system is connected with an inlet of the sulfuric acid deep concentration system, and a concentrated water outlet of the sulfuric acid deep concentration system is connected with the sulfuric acid storage tank; a water production outlet of the nanofiltration membrane system is connected with an inlet of the acid deep concentration system, and a concentrated water outlet of the acid deep concentration system is connected with the monovalent acid storage tank; and the water production outlet of the liquid caustic soda deep concentration system, the water production outlet of the sulfuric acid deep concentration system and the water production outlet of the acid deep concentration system are all connected with the inlet of the reuse water pool.
16. The miscellaneous salt resource treatment system of claim 14, wherein the liquid caustic soda depth concentration system, the sulfuric acid depth concentration system and the acid depth concentration system are any one or a combination of several of a membrane concentration system, an electrodialysis system, an MVR evaporation system, a TVR evaporation system or a multi-effect evaporation system.
17. The miscellaneous salt resource treatment system of claim 15, wherein the liquid caustic soda depth concentration system, the sulfuric acid depth concentration system and the acid depth concentration system are any one or a combination of several of a membrane concentration system, an electrodialysis system, an MVR evaporation system, a TVR evaporation system or a multi-effect evaporation system.
18. A system for recycling mixed salt according to any one of claims 11, 12, 15, 16 and 17, wherein the water outlet of the electrodialysis concentration system is connected to the inlet of a drying concentration system, the concentrated water outlet of the drying concentration system is connected to the inlet of the spray dryer, and the drying concentration system is a membrane concentration system.
19. A miscellaneous salt recycling treatment system as claimed in claim 13, wherein the water outlet of the electrodialysis concentration system is connected with the inlet of a drying concentration system, the concentrated water outlet of the drying concentration system is connected with the inlet of the spray dryer, and the drying concentration system is a membrane concentration system.
20. A miscellaneous salt recycling treatment system as claimed in claim 14, wherein the water outlet of the electrodialysis concentration system is connected with the inlet of a drying concentration system, the concentrated water outlet of the drying concentration system is connected with the inlet of the spray dryer, and the drying concentration system is a membrane concentration system.
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