CN114436295A - Purification and reuse method of industrial sodium sulfate waste salt - Google Patents
Purification and reuse method of industrial sodium sulfate waste salt Download PDFInfo
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- CN114436295A CN114436295A CN202210014314.1A CN202210014314A CN114436295A CN 114436295 A CN114436295 A CN 114436295A CN 202210014314 A CN202210014314 A CN 202210014314A CN 114436295 A CN114436295 A CN 114436295A
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- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 title claims abstract description 161
- 229910052938 sodium sulfate Inorganic materials 0.000 title claims abstract description 147
- 235000011152 sodium sulphate Nutrition 0.000 title claims abstract description 147
- 239000002699 waste material Substances 0.000 title claims abstract description 130
- 150000003839 salts Chemical class 0.000 title claims abstract description 82
- 238000000034 method Methods 0.000 title claims abstract description 40
- 238000000746 purification Methods 0.000 title abstract description 11
- 239000012266 salt solution Substances 0.000 claims abstract description 105
- 239000012535 impurity Substances 0.000 claims abstract description 98
- 238000001179 sorption measurement Methods 0.000 claims abstract description 78
- 238000000197 pyrolysis Methods 0.000 claims abstract description 33
- 230000009920 chelation Effects 0.000 claims abstract description 28
- 239000013043 chemical agent Substances 0.000 claims abstract description 25
- 239000007787 solid Substances 0.000 claims abstract description 21
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 20
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 claims abstract description 17
- 239000002893 slag Substances 0.000 claims abstract description 15
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 12
- 238000011084 recovery Methods 0.000 claims abstract description 8
- 230000007935 neutral effect Effects 0.000 claims abstract description 7
- 239000008235 industrial water Substances 0.000 claims abstract description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 41
- 239000000047 product Substances 0.000 claims description 30
- 239000000243 solution Substances 0.000 claims description 21
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 20
- 239000011575 calcium Substances 0.000 claims description 19
- 239000000126 substance Substances 0.000 claims description 18
- 238000005273 aeration Methods 0.000 claims description 17
- 239000002440 industrial waste Substances 0.000 claims description 16
- 239000002244 precipitate Substances 0.000 claims description 16
- 238000004064 recycling Methods 0.000 claims description 16
- -1 fluorine ions Chemical class 0.000 claims description 15
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- 229910052731 fluorine Inorganic materials 0.000 claims description 11
- 239000011737 fluorine Substances 0.000 claims description 11
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 10
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 9
- 229910052791 calcium Inorganic materials 0.000 claims description 9
- 239000003153 chemical reaction reagent Substances 0.000 claims description 9
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 8
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical group [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 8
- 239000003513 alkali Substances 0.000 claims description 6
- 238000006115 defluorination reaction Methods 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 238000005374 membrane filtration Methods 0.000 claims description 5
- 229910021529 ammonia Inorganic materials 0.000 claims description 4
- 238000007599 discharging Methods 0.000 claims description 4
- 238000004062 sedimentation Methods 0.000 claims description 4
- 239000010802 sludge Substances 0.000 claims description 4
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 3
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 3
- 238000010000 carbonizing Methods 0.000 claims description 3
- 239000000839 emulsion Substances 0.000 claims description 3
- 239000004571 lime Substances 0.000 claims description 3
- 230000014759 maintenance of location Effects 0.000 claims description 3
- 229920006395 saturated elastomer Polymers 0.000 claims description 3
- 239000000575 pesticide Substances 0.000 abstract description 9
- 229910019142 PO4 Inorganic materials 0.000 description 10
- 238000002425 crystallisation Methods 0.000 description 6
- 230000008025 crystallization Effects 0.000 description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 5
- 239000003814 drug Substances 0.000 description 5
- 244000005700 microbiome Species 0.000 description 5
- 239000007789 gas Substances 0.000 description 4
- 239000002351 wastewater Substances 0.000 description 4
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 3
- 238000001704 evaporation Methods 0.000 description 3
- 230000008020 evaporation Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000001471 micro-filtration Methods 0.000 description 3
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 3
- 241000894006 Bacteria Species 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000001506 calcium phosphate Substances 0.000 description 2
- 229910000389 calcium phosphate Inorganic materials 0.000 description 2
- 235000011010 calcium phosphates Nutrition 0.000 description 2
- 239000013522 chelant Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 241000282414 Homo sapiens Species 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 238000005842 biochemical reaction Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 238000009388 chemical precipitation Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 238000000909 electrodialysis Methods 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000015784 hyperosmotic salinity response Effects 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 230000009323 psychological health Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 235000002639 sodium chloride Nutrition 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- 239000004317 sodium nitrate Substances 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000002207 thermal evaporation Methods 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
- C01D5/16—Purification
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Processing Of Solid Wastes (AREA)
- Water Treatment By Sorption (AREA)
- Removal Of Specific Substances (AREA)
- Treatment Of Water By Ion Exchange (AREA)
Abstract
The invention discloses a purification and reuse method of industrial sodium sulfate waste salt, which comprises the following steps: 1. pyrolyzing solid industrial sodium sulfate waste salt to carbonize part of organic matters to form carbon slag; 2. dissolving the pyrolysis product in a salt dissolving pool by using industrial water to remove insoluble impurities, dissolving the soluble part to form a salt solution, and overflowing the salt solution into a chemical agent impurity removing pool; 3. removing inorganic impurities to obtain a sodium sulfate waste salt solution; 4. aerating the sodium sulfate waste salt solution to remove ammonia nitrogen impurities; 5. adding sulfuric acid to remove residual chemical agents, and adjusting the pH value to be neutral; 6. removing organic and inorganic impurities from the sodium sulfate waste salt solution through adsorption by an adsorption column; 7. sodium sulfate waste salt solution is sent to a chelation working section to remove Ca2+、Mg2+(ii) a 8. Crystallizing the waste sodium sulfate salt solution to obtain a sodium sulfate product. The method can effectively treat the industrial sodium sulfate waste salt containing organic matters and various inorganic impurities generated in the pharmaceutical and pesticide industries, and the purity and recovery rate of the treated sodium sulfate product are high.
Description
Technical Field
The invention relates to a resource method of industrial waste salt, in particular to a purification and reutilization method of industrial sodium sulfate waste salt.
Background
Along with the increasing production level of fine chemical fields such as medicine, pesticide, chemical industry, dye and the like in China, the yield of industrial waste salt is also increased year by year. The industrial waste salt has the characteristics of various types, complex components, wide sources, high content of toxic and harmful substances, great harm to the environment and the like. Waste salt from the pharmaceutical and pesticide industries mainly comprises sodium chloride, sodium sulfate and sodium nitrate, wherein the inorganic impurity contained in the waste salt is Ca2+、Mg2+、Al3+、PO4 3-、NH3N, and the like, and 10-20% of organic matters are also included. The sodium sulfate waste salt, which is a common industrial waste salt, contains the harmful substances, so that the sodium sulfate waste salt can cause serious harm to the ecological environment and physical and psychological health of human beings without regular treatment, greatly influences the recycling of resources and is not beneficial to sustainable development.
The Chinese invention patent CN201910177011.X discloses a method for recovering sodium sulfate from sodium sulfate-containing waste salt slag, which adopts a combined process of heat treatment, dissolution and water washing, multi-stage purification and impurity removal, and evaporation, concentration and crystallization by a thermal method to treat the sodium sulfate-containing waste salt slag. The heat treatment is to fully decompose the organic components in the sodium sulfate-containing waste salt slag at high temperature; the dissolving and washing treatment is to fully dissolve the waste salt components in the sodium sulfate-containing waste salt slag and remove the residual carbon black slag through solid-liquid separation; the purification and impurity removal treatment adopts the technologies of chemical precipitation, filtration and the like to remove impurity components such as metal ions and the like in the salt solution; the thermal evaporation concentration crystallization treatment is to treat the clean salt solution by adopting a steam heating evaporation technology to obtain a sodium sulfate product. The method is suitable for the sodium sulfate waste salt slag with high organic impurity content and inorganic impurities including Mg, Cu, Ni, Zn and Al, has no obvious purification effect on the sodium sulfate waste salt containing impurities such as ammonia nitrogen, phosphorus, fluorine and the like generated in the pesticide and medicine industries, and can treat the waste salt with single type, so that the method is not suitable for the sodium sulfate waste salt from the pesticide and medicine industries.
Chinese invention patent CN202011164175.8 discloses a treatment device and a resource method for sodium sulfate wastewater, the biochemical reaction unit of the method is a high-efficiency compound microorganism bacterium, the salt tolerance of the bacterium is fully utilized to carry out biochemical treatment on the sodium sulfate wastewater, most organic matters are degraded, then an electrodialysis unit is added at the tail end of the biochemical unit, the effluent of the biochemical treatment is concentrated, the concentrated water is subjected to MVR evaporation treatment, and sodium sulfate is recycled. The method has high requirement on the quality of the treated industrial wastewater, harmful substances in the wastewater produced in the pesticide industry can inhibit the growth of microorganisms and even kill the microorganisms, the microorganisms are difficult to survive, and the temperature of the wastewater also needs to be adjusted to a temperature suitable for the growth of the microorganisms to facilitate the treatment. Therefore, the application of the method has great limitation.
Disclosure of Invention
The invention aims to provide a method for purifying and recycling industrial sodium sulfate waste salt, which can effectively treat the industrial sodium sulfate waste salt containing organic matters and various inorganic impurities generated in the pharmaceutical and pesticide industries, and has high purity and recovery rate of the treated sodium sulfate product.
The invention is realized by the following steps:
a purification and reuse method of industrial sodium sulfate waste salt comprises the following steps:
step 1: pyrolyzing solid industrial sodium sulfate waste salt at high temperature, and carbonizing partial organic matters in the solid industrial waste salt to form carbon slag;
step 2: dissolving the product subjected to high-temperature pyrolysis in the step 1 in a salt dissolving pool, introducing industrial water, keeping insoluble impurities in the pyrolysis product in the salt dissolving pool, dissolving soluble parts in the pyrolysis product to form a salt solution, and overflowing the salt solution into a chemical agent impurity removal pool;
and step 3: removing inorganic impurities in the salt solution to obtain a sodium sulfate waste salt solution;
and 4, step 4: aerating the sodium sulfate waste salt solution in an aeration water tank to remove ammonia nitrogen impurities in the sodium sulfate waste salt;
and 5: removing residual chemical agents in the sodium sulfate waste salt solution, and adjusting the pH value of the sodium sulfate waste salt solution to be neutral;
step 6: feeding the sodium sulfate waste salt solution with the pH value adjusted to be neutral into an adsorption working section, and adsorbing by an adsorption column to remove organic and inorganic impurities;
and 7: sending the sodium sulfate waste salt solution after adsorption and impurity removal into a chelation working section, and removing residual Ca by chelation2+、Mg2 +；
And 8: removal of residual Ca2+、Mg2+Crystallizing the waste sodium sulfate salt solution by an evaporator to obtain a sodium sulfate product.
In the step 1, the pyrolysis temperature is 400-700 ℃, and the TOC concentration content of the solid industrial waste salt after pyrolysis is less than 10 ppm.
In the step 1, the solid industrial sodium sulfate waste salt contains organic impurities and inorganic impurities, wherein the content of the organic impurities is 10%, and the inorganic impurities comprise Ca2+、Mg2+、PO4 3-、F-、NH3-one or more of N.
In the step 2, the concentration of the salt solution is 390-410g/L, the temperature is 40-60 ℃, and the retention time of the pyrolysis product in the salt dissolving pool is 1.5-3 h.
The step 3 comprises the following steps:
step 3.1: adding alkali liquor into the chemical agent impurity removal pool to ensure that the pH value of the solution in the chemical agent impurity removal pool is more than 11, and removing Mg in the salt solution2+(ii) a The alkali liquor is sodium hydroxide solution with the concentration of 15-30%;
step 3.2: adding a calcium reagent into the chemical agent impurity removal tank to remove PO in the salt solution4 3-(ii) a The calcium reagent is calcium hydroxide solution in the state of saturated clear lime emulsion, and the addition amount of the calcium hydroxide solution is PO4 3-1.2-1.5 times of the stoichiometric number required for generating precipitates;
step 3.3: adding sodium carbonate solution into the chemical agent impurity removal poolRemoving excess Ca brought in by the calcium reagent2+(ii) a The concentration of the sodium carbonate solution is 15 percent, and the adding amount of the sodium carbonate solution is Ca2+1.1-1.2 times of the stoichiometric number required for generating precipitates;
step 3.4: and (3) filtering the precipitate insoluble substances generated in the steps 3.1 to 3.3 through physical sedimentation and membrane filtration, and discharging the precipitate insoluble substances from a sludge discharge port to obtain the sodium sulfate waste salt solution.
In the step 4, a heat exchanger is arranged in the aeration water tank, and the sodium sulfate waste salt solution is heated by the heat exchanger in the aeration process; the aeration time is 30-60min, the heating temperature of the heat exchanger is 60-70 ℃, and the total ammonia concentration of the aerated waste sodium sulfate salt solution is reduced to below 1 mg/L.
In the step 5, the pH value of the waste sodium sulfate salt solution is adjusted to 6-8 by sulfuric acid.
In the step 6, the adsorption column comprises at least one of an ammonia nitrogen adsorption column, a defluorination adsorption column and an active carbon adsorption column, the adsorption time of the adsorption column is 10-30min, and the adsorption temperature is 30-40 ℃; after the impurities are removed through adsorption by an adsorption column, the content of fluorine ions in the sodium sulfate waste salt solution is less than 1mg/L, and the content of ammonia nitrogen ions is less than 3 mg/L.
In the step 7, a first intermediate water tank for temporarily storing the sodium sulfate waste salt solution after adsorption and impurity removal is further included, an input end of the first intermediate water tank is connected with an output end of the adsorption working section, one output end of the first intermediate water tank is connected with an input end of the adsorption working section, and the other output end of the first intermediate water tank is connected with an input end of the chelation working section;
and step 8, the system further comprises a second intermediate water tank for temporarily storing the chelated sodium sulfate waste salt solution, wherein the input end of the second intermediate water tank is connected with the output end of the chelation working section, one output end of the second intermediate water tank is connected with the input end of the chelation working section, and the other output end of the second intermediate water tank is connected with the input end of the evaporator.
In the sodium sulfate product obtained in the step 8, the purity of the sodium sulfate is more than 99%, and the recovery rate of the sodium sulfate is more than 96.2%.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention adopts the high-temperature pyrolysis process, can deeply remove TOC (Total Organic Carbon) in the solid industrial sodium sulfate waste salt, and can reduce the TOC concentration to below 10 ppm; meanwhile, a method of chemical agent impurity removal, microfiltration, high-temperature stripping, adsorption, chelation and evaporative crystallization multi-section combined use is combined, organic impurities and various inorganic impurities in a salt solution can be deeply removed, so that a finally obtained sodium sulfate product meets the standard of industrial anhydrous sodium sulfate (GBT 6009-2014), and sustainable economic development is realized.
2. The invention has the advantages that the surpassing pipeline formed by the arrangement of the adsorption columns is arranged, the material consumption is reasonable, the operation cost is saved, the industrial sodium sulfate waste salt containing different inorganic impurities can be treated, the corresponding process route can be selected according to the actual condition of the waste salt, the recycling of the industrial sodium sulfate waste salt is realized, and the treatment cost is reduced.
3. The method has wide applicability, can specially remove various impurities in the sodium sulfate waste salt generated in the pharmaceutical and pesticide industries, has thorough impurity treatment, has high recovery rate of the purified sodium sulfate product, and can be applied to the production and manufacturing industries of common glass, dye, paper making and the like again to promote the development of green circular economy.
The method treats the industrial sodium sulfate waste salt containing organic matters and various inorganic impurities through the processes of pyrolysis, medicament impurity removal, microfiltration, high-temperature air stripping, adsorption, chelation and evaporative crystallization, obtains a sodium sulfate product with the purity of sodium sulfate more than 99%, has high recovery rate, and realizes the resource utilization of the industrial sodium sulfate waste salt generated in the industries of medicines, pesticides and the like.
Drawings
FIG. 1 is a flow chart of the purification and reuse method of waste sodium sulfate of the present invention.
Detailed Description
The invention is further described with reference to the following figures and specific examples.
Referring to the attached figure 1, the method for purifying and recycling the industrial sodium sulfate waste salt comprises the following steps:
step 1: the solid industrial sodium sulfate waste salt is sent to a high-temperature pyrolysis furnace for pyrolysis, organic impurities in the solid industrial waste salt are fully combusted to form pyrolysis gas, and partial organic matters in the solid industrial waste salt are gradually carbonized to form carbon slag, so that the aim of deeply removing the organic matters in the solid industrial waste salt is fulfilled.
Preferably, the pyrolysis temperature is 400-700 ℃, and the TOC concentration content of the solid industrial waste salt after pyrolysis is less than 10 ppm. Pyrolysis gas generated after pyrolysis of the solid industrial waste salt can be treated by subsequent purification equipment.
The solid industrial sodium sulfate waste salt contains organic impurities and inorganic impurities, wherein the content of the organic impurities is about 10 percent, and the inorganic impurities comprise Ca2+、Mg2+、PO4 3-、F-、NH3-one or more of N.
Step 2: and (2) dissolving the product subjected to high-temperature pyrolysis in the step (1) in a salt dissolving pool, introducing industrial water, leaving insoluble impurities such as carbon slag in the pyrolysis product in the salt dissolving pool, removing the insoluble impurities such as the carbon slag, dissolving the soluble part in the pyrolysis product to form a salt solution, and overflowing the salt solution into a chemical agent impurity removal pool.
Preferably, the concentration of the salt solution is 390-410g/L, and the temperature is 40-60 ℃.
Preferably, the retention time of the pyrolysis product in the salt dissolving pool is 1.5-3 h.
And step 3: and removing inorganic impurities in the salt solution to obtain a waste sodium sulfate salt solution.
Step 3.1: adding alkali liquor, preferably sodium hydroxide solution, into the chemical impurity removal tank, wherein the concentration of the alkali liquor is 15-30%, so that the pH value of the solution in the chemical impurity removal tank is more than 11, and promoting Mg in the solution2+Formation of Mg (OH)2Precipitating to remove Mg in salt solution2+。
Step 3.2: adding calcium reagent into the chemical impurity removal tank, wherein the calcium reagent is preferably calcium hydroxide solution in the state of saturated clear lime emulsion, and the addition amount of the calcium hydroxide solution is PO4 3-The amount of the chemical reaction needed for generating the precipitate is 1.2 to 1.5 times of the amount of the chemical reaction needed for generating the precipitate, and PO is added4 3-Converting into calcium phosphate precipitate, and removing PO from the salt solution4 3-And the like, most species of high valency cations.
Step 3.3: adding sodium carbonate solution into the chemical agent impurity removal tank, wherein the concentration of the sodium carbonate solution is 15%, and the adding amount of the sodium carbonate solution is Ca2+Removing excessive Ca brought by calcium reagent, wherein the amount of the excessive Ca is 1.1-1.2 times of the stoichiometric number of the generated precipitate2+。
Step 3.4: and (3) filtering the precipitate insoluble substances generated in the steps 3.1 to 3.3 through physical sedimentation and membrane filtration, and discharging the precipitate insoluble substances from a sludge discharge port to obtain the sodium sulfate waste salt solution.
Preferably, the membrane filtration can be performed by using a Goll membrane.
And 4, step 4: and aerating the sodium sulfate waste salt solution in an aeration water tank, and removing ammonia nitrogen impurities in the sodium sulfate waste salt by nitrogen stripping. Preferably, the aeration time is 30-60 min.
In the step 4, the heat exchanger is arranged in the aeration water tank, and the sodium sulfate waste salt solution is heated by the heat exchanger in the aeration process, so that the aeration effect can be improved, and the removal of ammonia nitrogen impurities is facilitated. Preferably, the heating temperature of the heat exchanger is 60-70 ℃.
In the step 4, the total ammonia concentration of the aerated waste sodium sulfate salt solution is reduced to below 1 mg/L.
And 5: adding sulfuric acid into the sodium sulfate waste salt solution, wherein the concentration of the sulfuric acid can be determined according to the actual regulation requirement of the pH value, and removing the residual chemical agent, such as the excessive OH added in the chemical agent impurity removal tank-、CO3 2-And simultaneously, adjusting the pH value of the sodium sulfate waste salt solution to be neutral through acid-base neutralization reaction, preferably, adjusting the pH value of the sodium sulfate waste salt solution to be 6-8.
Step 6: and (3) feeding the sodium sulfate waste salt solution with the pH value adjusted to be neutral into an adsorption working section, and adsorbing and removing organic impurities and inorganic impurities through an adsorption column. At the moment, the sodium sulfate waste salt solution contains fluorine ions and incompletely removed ammonia nitrogen ions, the fluorine ions and the ammonia nitrogen ions can be deeply adsorbed through the fluorine removal adsorption column and the ammonia nitrogen adsorption column, the content of the fluorine ions in the sodium sulfate waste salt solution after impurity removal through adsorption of the adsorption column is less than 1mg/L, and the content of the ammonia nitrogen ions is less than 3 mg/L.
Preferably, the adsorption column comprises at least one of an ammonia nitrogen adsorption column, a defluorination adsorption column and an activated carbon adsorption column, the activated carbon adsorption column is used for adsorbing organic impurities, the defluorination adsorption column is used for adsorbing fluorine ions, the ammonia nitrogen adsorption column is used for adsorbing ammonia nitrogen ions, the type and the number of the adsorption column can be selected in a targeted manner according to the actual organic impurities and inorganic impurities contained in the sodium sulfate waste salt solution, the adsorption time is 10-30min, and the adsorption temperature is 30-40 ℃.
In the adsorption section, different types of adsorption columns can be arranged by adopting a surpassing pipeline and are used for treating the sodium sulfate waste salt solution with different inorganic impurity types and contents, and a proper adsorption impurity removal route can be selected according to the type and the content of the inorganic impurities in the sodium sulfate waste salt solution, for example: the sodium sulfate waste salt solution can be directly adsorbed and purified by an ammonia nitrogen adsorption column; the waste sodium sulfate salt solution can be directly adsorbed and purified by a defluorination adsorption column; the sodium sulfate waste salt solution can be directly adsorbed and purified by an activated carbon adsorption column; the sodium sulfate waste salt solution can be subjected to adsorption impurity removal and the like sequentially through an activated carbon adsorption column, a defluorination adsorption column and an ammonia nitrogen adsorption column.
And 7: temporarily storing the sodium sulfate waste salt solution subjected to adsorption impurity removal to a first intermediate water tank, and then sending the sodium sulfate waste salt solution to a chelation working section, wherein the sodium sulfate waste salt solution is deeply subjected to removal of residual Ca through chelate resin in the chelation working section2+、Mg2+After deep removal of Ca2+、Mg2+The total content of (A) is not more than 0.07 w/%.
The input end of the first middle water tank is connected with the output end of the adsorption working section, one output end of the first middle water tank is connected with the input end of the adsorption working section, the other output end of the first middle water tank is connected with the input end of the chelation working section, and through the cyclic connection of the first middle water tank and the adsorption working section, the sodium sulfate waste salt solution can be returned to the adsorption working section for re-adsorption when the adsorption of the adsorption working section is incomplete, and the sodium sulfate waste salt solution is conveyed to the next working section, namely the chelation working section, until the adsorption of the adsorption working section is complete.
And 8: deep removal of residual Ca2+、Mg2+And temporarily storing the sodium sulfate waste salt solution to a second intermediate water tank to ensure thorough chelation of the sodium sulfate waste salt solution, and then feeding the sodium sulfate waste salt solution to an evaporator for crystallization to obtain a sodium sulfate product, wherein the purity of sodium sulfate in the sodium sulfate product is more than 99%, the recovery rate of sodium sulfate is more than 96.2%, and the sodium sulfate product meets the standard of 'industrial anhydrous sodium sulfate' (GBT 6009-2014).
The input of water tank is connected with the output of chelation workshop section in the middle of the second, and an output of water tank is connected with the input of chelation workshop section in the middle of the second, and another output of water tank is connected with the input of evaporimeter in the middle of the second, through the water tank and the cyclic connection of chelation workshop section in the middle of the second, can return the sodium sulfate waste salt solution to the chelation workshop section when the chelation of chelation workshop section is not thorough and carry out chelation again, and until the chelation of chelation workshop section is thorough, each item index of sodium sulfate waste salt solution is at this moment: TOC =5.2mg/L, Ca2++Mg2+=0.05mg/L， PO4 3-=0.9mg/L，F-=0.3mg/L，NH3N =0.9 mg/L, after which the sodium sulphate waste salt solution is sent to the next section, the evaporator. And returning the evaporated condensate water to the salt melting pool for recycling.
Example 1:
step 1: a batch with 10 percent of organic impurities and inorganic impurities (Ca)2+、Mg2+、PO4 3-、F-、NH3And (4) pyrolyzing the solid industrial sodium sulfate waste salt in the-N) in a high-temperature pyrolysis furnace at the temperature of 400-700 ℃, fully burning organic impurities in the solid industrial waste salt to form pyrolysis gas, gradually carbonizing a part of organic matters in the solid industrial waste salt to form carbon slag, and enabling the TOC concentration content after pyrolysis to be less than 10ppm so as to achieve the purpose of deeply removing the organic matters in the solid industrial waste salt. The pyrolysis gas may be treated by subsequent purification equipment.
Step 2: dissolving the pyrolysis product in a salt dissolving pool, introducing industrial water, staying for 1.5h, leaving insoluble impurities such as carbon slag in the pyrolysis product in the salt dissolving pool, removing the insoluble impurities such as carbon slag, dissolving the soluble part in the pyrolysis product to form a salt solution with the concentration of 400g/L and the temperature of 40 ℃, and overflowing the salt solution into a chemical agent impurity removal pool from an overflow port at the upper end of the salt dissolving pool.
And step 3: and (3) removing inorganic impurities in the salt solution for the first time to obtain a sodium sulfate waste salt solution.
Step 3.1: adding 15-30% sodium hydroxide solution into the chemical agent impurity removal tank to make the pH value of the solution in the chemical agent impurity removal tank reach 11-12. Promoting Mg in salt solution2+Formation of Mg (OH)2Precipitating to remove Mg preliminarily2+(ii) a Simultaneously facilitates the subsequent PO4 3-Precipitate is formed and alkaline environment is provided for the blowing-off of ammonia nitrogen aeration of the next section.
Step 3.2: adding excessive calcium hydroxide solution with the stoichiometric number being 1.5 times of the impurity content into a chemical agent impurity removal pool, and adding PO4 3-Converting into calcium phosphate precipitate, and removing PO from sodium sulfate solution4 3-。
Step 3.3: adding sodium carbonate solution with the stoichiometric number 1.15 times of the impurity content into the chemical agent impurity removal tank to remove excessive Ca brought by calcium hydroxide2+。
Step 3.4: and (3) filtering and precipitating the precipitated insoluble substances generated in the steps 3.1-3.3 through physical sedimentation and Gole membrane filtration, filtering and removing the precipitated insoluble substances in the suspension by utilizing the microfiltration action of the Gole membrane, and discharging the precipitated insoluble substances from a sludge discharge port to obtain the sodium sulfate waste salt solution.
And 4, step 4: and aerating the sodium sulfate waste salt solution in an aeration water tank, and removing ammonia nitrogen impurities in the sodium sulfate waste salt by nitrogen stripping. The aeration time is 30-60 minutes, the solution temperature is heated to 60-70 ℃ by a heat exchanger in the aeration process, ammonia nitrogen impurities are effectively removed by utilizing high temperature and nitrogen gas blowing, and the total ammonia concentration in the sodium sulfate waste salt solution is reduced to be below 1 mg/L. At this time, the waste sodium sulfate salt solution only contains fluorine ions and trace organic substances which are not completely removed in the previous working section.
And 5: and adding sulfuric acid into the sodium sulfate waste salt solution to remove residual chemical agents, and adjusting the pH value of the sodium sulfate waste salt solution to 6-8.
Step 6: sending the sodium sulfate waste salt solution with the pH value of 6-8 to an adsorption working section, and sequentially adsorbing and removing incompletely-removed trace organic substances through a fluorine adsorption column and an ammonia nitrogen adsorption column, wherein the adsorption time is 10-30 minutes, the adsorption temperature is 30-40 ℃, so that the content of fluorine ions in the sodium sulfate waste salt solution after adsorption and impurity removal is less than 1mg/L, and the content of ammonia nitrogen ions is less than 3 mg/L.
And 7: temporarily storing the sodium sulfate waste salt solution subjected to adsorption impurity removal to a first intermediate water tank, completely adsorbing the sodium sulfate waste salt solution in the first intermediate water tank, and then sending the sodium sulfate waste salt solution to a chelation section, wherein the sodium sulfate waste salt solution is deeply subjected to removal of residual Ca through chelate resin in the chelation section2+、Mg2+。
And 8: sodium sulfate waste salt solution of degree of depth desorption residual ion keeps in to water tank in the middle of the second, and after the chelation of sodium sulfate waste salt solution of water tank was thorough in the middle of the second, each item index of the waste salt solution of sodium sulfate was this moment: TOC =5.2mg/L, Ca2++Mg2+=0.05mg/L， PO4 3-=0.9mg/L，F-=0.3mg/L，NH3-N =0.9 mg/L. And then, feeding the sodium sulfate product into an evaporator for crystallization to obtain a sodium sulfate product, wherein the purity of sodium sulfate in the sodium sulfate product is more than 99%, and the recovery rate of sodium sulfate reaches 96.2%, and meets the standard of Industrial anhydrous sodium sulfate (GBT 6009-2014). And returning the evaporated condensate water to the salt melting pool for recycling.
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method for purifying and recycling industrial sodium sulfate waste salt is characterized by comprising the following steps: the method comprises the following steps:
step 1: pyrolyzing solid industrial sodium sulfate waste salt at high temperature, and carbonizing partial organic matters in the solid industrial waste salt to form carbon slag;
and 2, step: dissolving the product subjected to high-temperature pyrolysis in the step 1 in a salt dissolving pool, introducing industrial water to enable insoluble impurities in the pyrolysis product to remain in the salt dissolving pool, dissolving soluble parts in the pyrolysis product to form a salt solution, and overflowing the salt solution to a chemical agent impurity removal pool;
and step 3: removing inorganic impurities in the salt solution to obtain a sodium sulfate waste salt solution;
and 4, step 4: aerating the sodium sulfate waste salt solution in an aeration water tank to remove ammonia nitrogen impurities in the sodium sulfate waste salt;
and 5: removing residual chemical agents in the sodium sulfate waste salt solution, and adjusting the pH value of the sodium sulfate waste salt solution to be neutral;
step 6: feeding the sodium sulfate waste salt solution with the pH value adjusted to be neutral into an adsorption working section, and adsorbing by an adsorption column to remove organic and inorganic impurities;
and 7: sending the sodium sulfate waste salt solution after adsorption and impurity removal into a chelation working section, and removing residual Ca by chelation2+、Mg2+；
And 8: removal of residual Ca2+、Mg2+Crystallizing the waste sodium sulfate salt solution by an evaporator to obtain a sodium sulfate product.
2. The method for purifying and recycling industrial sodium sulfate waste salt as claimed in claim 1, which is characterized in that: in the step 1, the pyrolysis temperature is 400-700 ℃, and the TOC concentration content of the solid industrial waste salt after pyrolysis is less than 10 ppm.
3. The method for purifying and recycling industrial sodium sulfate waste salt according to claim 1 or 2, characterized in that: in the step 1, the solid industrial sodium sulfate waste salt contains organic impurities and inorganic impurities, wherein the content of the organic impurities is 10%, and the inorganic impurities comprise Ca2+、Mg2+、PO4 3-、F-、NH3-one or more of N.
4. The method for purifying and recycling industrial sodium sulfate waste salt as claimed in claim 1, which is characterized in that: in the step 2, the concentration of the salt solution is 390-410g/L, the temperature is 40-60 ℃, and the retention time of the pyrolysis product in the salt dissolving pool is 1.5-3 h.
5. The method for purifying and recycling industrial sodium sulfate waste salt as claimed in claim 1, which is characterized in that: the step 3 comprises the following steps:
step 3.1: adding alkali liquor into the chemical agent impurity removal pool to ensure that the pH value of the solution in the chemical agent impurity removal pool is more than 11, and removing Mg in the salt solution2+；
The alkali liquor is sodium hydroxide solution with the concentration of 15-30%;
step 3.2: adding a calcium reagent into the chemical agent impurity removal tank to remove PO in the salt solution4 3-；
The calcium reagent is calcium hydroxide solution in the state of saturated clear lime emulsion, and the addition amount of the calcium hydroxide solution is PO4 3-1.2-1.5 times of the stoichiometric number required for generating precipitates;
step 3.3: adding sodium carbonate solution into the chemical agent impurity removal tank to remove excessive Ca brought by the calcium reagent2+；
The concentration of the sodium carbonate solution is 15 percent, and the adding amount of the sodium carbonate solution is Ca2+1.1-1.2 times of the stoichiometric number required for generating precipitates;
step 3.4: and (3) filtering the precipitate insoluble substances generated in the steps 3.1 to 3.3 through physical sedimentation and membrane filtration, and discharging the precipitate insoluble substances from a sludge discharge port to obtain the sodium sulfate waste salt solution.
6. The method for purifying and recycling industrial sodium sulfate waste salt as claimed in claim 1, which is characterized in that: in the step 4, a heat exchanger is arranged in the aeration water tank, and the sodium sulfate waste salt solution is heated by the heat exchanger in the aeration process; aerating for 30-60min, and heating at 60-70 deg.C with the heat exchanger; the total ammonia concentration of the sodium sulfate waste salt solution after aeration is reduced to below 1 mg/L.
7. The method for purifying and recycling industrial sodium sulfate waste salt as claimed in claim 1, which is characterized in that: in the step 5, the pH value of the waste sodium sulfate salt solution is adjusted to 6-8 by sulfuric acid.
8. The method for purifying and recycling industrial sodium sulfate waste salt as claimed in claim 1, which is characterized in that: in the step 6, the adsorption column comprises at least one of an ammonia nitrogen adsorption column, a defluorination adsorption column and an active carbon adsorption column, the adsorption time of the adsorption column is 10-30min, and the adsorption temperature is 30-40 ℃; after the impurities are removed through adsorption by an adsorption column, the content of fluorine ions in the sodium sulfate waste salt solution is less than 1mg/L, and the content of ammonia nitrogen ions is less than 3 mg/L.
9. The method for purifying and recycling industrial sodium sulfate waste salt as claimed in claim 1, which is characterized in that: in the step 7, a first intermediate water tank for temporarily storing the sodium sulfate waste salt solution after adsorption and impurity removal is further included, an input end of the first intermediate water tank is connected with an output end of the adsorption working section, one output end of the first intermediate water tank is connected with an input end of the adsorption working section, and the other output end of the first intermediate water tank is connected with an input end of the chelation working section;
and step 8, the system further comprises a second intermediate water tank for temporarily storing the chelated sodium sulfate waste salt solution, wherein the input end of the second intermediate water tank is connected with the output end of the chelation working section, one output end of the second intermediate water tank is connected with the input end of the chelation working section, and the other output end of the second intermediate water tank is connected with the input end of the evaporator.
10. The method for purifying and recycling industrial sodium sulfate waste salt as claimed in claim 1, which is characterized in that: in the sodium sulfate product obtained in the step 8, the purity of the sodium sulfate is more than 99%, and the recovery rate of the sodium sulfate is more than 96.2%.
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