CN114873613B - Method for refining and recovering sodium hypophosphite by using byproduct sodium sulfate - Google Patents
Method for refining and recovering sodium hypophosphite by using byproduct sodium sulfate Download PDFInfo
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- CN114873613B CN114873613B CN202210530148.0A CN202210530148A CN114873613B CN 114873613 B CN114873613 B CN 114873613B CN 202210530148 A CN202210530148 A CN 202210530148A CN 114873613 B CN114873613 B CN 114873613B
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- sodium sulfate
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- KWSLGOVYXMQPPX-UHFFFAOYSA-N 5-[3-(trifluoromethyl)phenyl]-2h-tetrazole Chemical compound FC(F)(F)C1=CC=CC(C2=NNN=N2)=C1 KWSLGOVYXMQPPX-UHFFFAOYSA-N 0.000 title claims abstract description 45
- 229910001379 sodium hypophosphite Inorganic materials 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims abstract description 44
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 title claims abstract description 40
- 229910052938 sodium sulfate Inorganic materials 0.000 title claims abstract description 38
- 235000011152 sodium sulphate Nutrition 0.000 title claims abstract description 38
- 239000006227 byproduct Substances 0.000 title claims abstract description 16
- 238000007670 refining Methods 0.000 title claims abstract description 11
- 239000000706 filtrate Substances 0.000 claims abstract description 129
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 78
- 230000023556 desulfurization Effects 0.000 claims abstract description 78
- 239000007788 liquid Substances 0.000 claims abstract description 72
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 39
- 239000000463 material Substances 0.000 claims abstract description 28
- 238000004519 manufacturing process Methods 0.000 claims abstract description 25
- 238000002425 crystallisation Methods 0.000 claims abstract description 23
- 230000008025 crystallization Effects 0.000 claims abstract description 23
- 239000013049 sediment Substances 0.000 claims abstract description 20
- 239000000047 product Substances 0.000 claims abstract description 16
- 239000003674 animal food additive Substances 0.000 claims abstract description 9
- 238000002156 mixing Methods 0.000 claims abstract description 5
- 238000004806 packaging method and process Methods 0.000 claims abstract description 5
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 44
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 22
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 22
- 238000001914 filtration Methods 0.000 claims description 20
- 239000003513 alkali Substances 0.000 claims description 16
- 238000000926 separation method Methods 0.000 claims description 16
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 15
- 229910052791 calcium Inorganic materials 0.000 claims description 15
- 239000011575 calcium Substances 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 15
- 239000002893 slag Substances 0.000 claims description 15
- 239000013078 crystal Substances 0.000 claims description 14
- 239000012452 mother liquor Substances 0.000 claims description 13
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims description 12
- 239000001569 carbon dioxide Substances 0.000 claims description 11
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 11
- 239000002244 precipitate Substances 0.000 claims description 11
- 230000002441 reversible effect Effects 0.000 claims description 10
- 238000003756 stirring Methods 0.000 claims description 10
- 238000004090 dissolution Methods 0.000 claims description 8
- 230000007935 neutral effect Effects 0.000 claims description 8
- RSIJVJUOQBWMIM-UHFFFAOYSA-L sodium sulfate decahydrate Chemical compound O.O.O.O.O.O.O.O.O.O.[Na+].[Na+].[O-]S([O-])(=O)=O RSIJVJUOQBWMIM-UHFFFAOYSA-L 0.000 claims description 8
- 238000005406 washing Methods 0.000 claims description 8
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 5
- 238000004321 preservation Methods 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 4
- 239000000292 calcium oxide Substances 0.000 claims description 3
- 235000012255 calcium oxide Nutrition 0.000 claims description 3
- 238000001556 precipitation Methods 0.000 claims description 3
- 238000003825 pressing Methods 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 3
- 239000000243 solution Substances 0.000 claims description 3
- 230000001105 regulatory effect Effects 0.000 claims 2
- 230000001276 controlling effect Effects 0.000 claims 1
- 239000010413 mother solution Substances 0.000 claims 1
- ACVYVLVWPXVTIT-UHFFFAOYSA-N phosphinic acid Chemical compound O[PH2]=O ACVYVLVWPXVTIT-UHFFFAOYSA-N 0.000 abstract description 14
- 238000004064 recycling Methods 0.000 abstract description 4
- 239000002994 raw material Substances 0.000 description 6
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 4
- 239000000920 calcium hydroxide Substances 0.000 description 4
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 4
- 229910001382 calcium hypophosphite Inorganic materials 0.000 description 4
- 229940064002 calcium hypophosphite Drugs 0.000 description 4
- 238000007747 plating Methods 0.000 description 4
- CNALVHVMBXLLIY-IUCAKERBSA-N tert-butyl n-[(3s,5s)-5-methylpiperidin-3-yl]carbamate Chemical compound C[C@@H]1CNC[C@@H](NC(=O)OC(C)(C)C)C1 CNALVHVMBXLLIY-IUCAKERBSA-N 0.000 description 4
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 235000011941 Tilia x europaea Nutrition 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 239000004571 lime Substances 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- XYFCBTPGUUZFHI-UHFFFAOYSA-N Phosphine Chemical compound P XYFCBTPGUUZFHI-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 239000001506 calcium phosphate Substances 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- KOUDKOMXLMXFKX-UHFFFAOYSA-N sodium oxido(oxo)phosphanium hydrate Chemical compound O.[Na+].[O-][PH+]=O KOUDKOMXLMXFKX-UHFFFAOYSA-N 0.000 description 2
- 239000002910 solid waste Substances 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
- 229940078499 tricalcium phosphate Drugs 0.000 description 2
- 229910000391 tricalcium phosphate Inorganic materials 0.000 description 2
- 235000019731 tricalcium phosphate Nutrition 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 229910001378 barium hypophosphite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000000909 electrodialysis Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000005886 esterification reaction Methods 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 239000002932 luster Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052755 nonmetal Inorganic materials 0.000 description 1
- 230000009965 odorless effect Effects 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- ACVYVLVWPXVTIT-UHFFFAOYSA-M phosphinate Chemical compound [O-][PH2]=O ACVYVLVWPXVTIT-UHFFFAOYSA-M 0.000 description 1
- 229910000073 phosphorus hydride Inorganic materials 0.000 description 1
- VKJKEPKFPUWCAS-UHFFFAOYSA-M potassium chlorate Chemical compound [K+].[O-]Cl(=O)=O VKJKEPKFPUWCAS-UHFFFAOYSA-M 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
- 235000011121 sodium hydroxide Nutrition 0.000 description 1
- 230000001954 sterilising effect Effects 0.000 description 1
- 238000004659 sterilization and disinfection Methods 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Classifications
-
- 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
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23K—FODDER
- A23K20/00—Accessory food factors for animal feeding-stuffs
- A23K20/20—Inorganic substances, e.g. oligoelements
- A23K20/24—Compounds of alkaline earth metals, e.g. magnesium
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/165—Hypophosphorous acid; Salts thereof
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/584—Recycling of catalysts
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Polymers & Plastics (AREA)
- Engineering & Computer Science (AREA)
- Animal Husbandry (AREA)
- Zoology (AREA)
- Food Science & Technology (AREA)
- Materials Engineering (AREA)
- Removal Of Specific Substances (AREA)
Abstract
The application discloses a method for refining and recycling sodium hypophosphite by using byproduct sodium sulfate, which comprises the following steps: mixing water and crude sodium sulfate in a primary material tank, and separating the material liquid in a first centrifugal machine; step 2): mixing the separated filter residues with added water in a secondary material chute, separating the material liquid in a second centrifuge, separating the material liquid to obtain finished sodium sulfate, packaging the finished sodium sulfate in a packaging workshop, and returning the separated filtrate to the primary material chute; step 3): the filtrate separated by the first centrifugal machine enters a crystallization kettle, is cooled and crystallized by low-temperature water sent by a low-temperature water system, is centrifugally separated in a third centrifugal machine, and is sent to a desulfurization process; step 4): the filtrate obtained by the desulfurization process enters a production line to produce sodium hypophosphite products; step 5): the sediment filtrate produced in the desulfurization procedure is used for producing feed additives; the application can effectively recycle the hypophosphorous acid in the byproduct sodium sulfate for recycling in the production of sodium hypophosphite.
Description
Technical Field
The application relates to the technical field of production of hypophosphorous acid and sodium hypophosphite, in particular to a method for refining and recycling sodium hypophosphite by using byproduct sodium sulfate.
Background
Sodium hypophosphite, also known as sodium hypophosphite, is a crystalline granular powder with pearl luster, is colorless, odorless, salty in taste and strong in deliquescence due to monoclinic crystals (needle-like crystals). The product is stable when stored in a dry state, can explode when exposed to strong heat, and can explode when mixed with potassium chlorate or other strong oxidants. Rapidly decomposing when heated to over 200 ℃ and releasing phosphine which can be spontaneously combusted. The sodium hypophosphite is mainly used as an electroless nickel plating reducing agent, and can be matched with other reagents to conveniently plate metal on glass fiber and plastic, so that the plating film is uniform and corrosion-resistant, and the method is particularly suitable for plating metal or nonmetal components with complicated switches and is very convenient to use. Meanwhile, sodium hypophosphite is also applied to the fields of medicine, plastic processing, plant sterilization and the like in a small amount.
Hypophosphorous acid is a very widely used fine chemical product, is mainly used as a reducing agent in the chemical plating, electroplating and organic synthesis industries, and can also be used as a catalyst for esterification reaction, a refrigerant and the production of high-purity sodium hypophosphite.
The traditional preparation method of hypophosphorous acid mainly comprises a chemical method, an ion exchange method and an electrodialysis method. The sodium hypophosphite manufacturer prepares weak acid from hypophosphorous acid by adopting a chemical method strong acid, and prepares the hypophosphorous acid by using concentrated sulfuric acid to react with sodium hypophosphite, so that sodium sulfate as a byproduct is obtained.
Disclosure of Invention
The application aims to overcome the defects, and provides a method for refining and recycling sodium hypophosphite by-product sodium sulfate, which can effectively recycle the hypophosphite in the by-product sodium sulfate for the production of sodium hypophosphite, and simultaneously improve the purity of sodium sulfate to more than 99%, thereby achieving the purposes of solid waste utilization, clean production and production cost reduction.
The application aims to solve the technical problems, and adopts the technical scheme that: a method for refining and recovering sodium hypophosphite by using byproduct sodium sulfate comprises the following steps:
step 1): mixing water and crude sodium sulfate in a primary material tank, pumping the solid-liquid mixture into a dissolution and washing kettle, stirring for a period of time, and separating the feed liquid in a first centrifuge;
step 2): the filter residues obtained by separation of the first centrifugal machine enter a secondary material tank to be mixed with added water, then the mixture is pumped into an adjusting kettle, the pH value is kept to be neutral by adding alkali, after the mixture is stirred, reacted and aged for a period of time, the material liquid enters a second centrifugal machine to be separated, the separated finished product sodium sulfate enters a packaging workshop to be packaged, and the separated filtrate is returned to the primary material tank;
step 3): the filtrate separated by the first centrifugal machine is firstly accumulated in a primary filtrate tank, then enters a crystallization kettle, is cooled and crystallized by low-temperature water sent by a low-temperature water system, is centrifugally separated in a third centrifugal machine, and the obtained solid crystal is returned to a primary material tank, and mother liquor is sent to a desulfurization process;
step 4): the filtrate obtained by the desulfurization process enters a production line to produce sodium hypophosphite products;
step 5): and using the precipitate filtrate generated in the desulfurization process for producing a feed additive.
Preferably, in the step 1), after the solid-liquid mixture is pumped into the dissolution and washing kettle, the temperature is controlled to be more than 50 ℃, and the mixture is stirred for half an hour and then enters a first centrifuge for heat preservation and separation.
Preferably, in the step 2), the temperature of the adjusting kettle is kept above 50 ℃, the pH value is kept to be neutral by adding alkali, the stirring reaction is carried out for one hour, and the feed liquid enters a second centrifugal machine for separation, thus obtaining the finished sodium sulfate with the content of more than or equal to 99 percent.
Preferably, in the step 3), the filtrate separated by the first centrifuge enters a crystallization kettle, the filtrate is cooled to below 10 ℃ for crystallization by low temperature water of 7 ℃ sent by a low temperature water system, sodium sulfate decahydrate crystals are separated out, and then the filtrate is centrifugally separated in a third centrifuge.
Preferably, the filtrate is further used for promoting precipitation of sodium sulfate decahydrate crystallization by adding a certain amount of seed crystals in the crystallization process of the crystallization kettle.
Preferably, the desulfurization process in the step 3) and the step 4) is specifically: the mother liquor is sent to a desulfurization kettle, and then quicklime is added for reaction to form calcium sulfate precipitate, so that sulfate in the solution is removed, the mixed material is sent to a filter press for filter pressing, the filtrate is sent to a desulfurization filtrate tank and then to a sodium hypophosphite product production line, and the precipitate filtrate is sent to a feed additive production workshop to serve as a calcium source.
Preferably, if the calcium content in the filtrate in the desulfurization filtrate tank is greater than 0.1%, liquid alkali is added into the filtrate tank and carbon dioxide is introduced into the filtrate tank to form calcium carbonate precipitate, and the liquid calcium content in the filtrate is reduced until the liquid calcium content in the filtrate is less than 0.1%.
Preferably, a reversible filtering system is arranged in the desulfurization filtrate tank and is used for filtering and separating the generated calcium carbonate.
Preferably, the reversible filtering system comprises a filter screen vertically arranged in a desulfurization filtrate tank, the desulfurization filtrate tank is of a square tank body structure, the filter screen is of a rectangular plate-shaped structure and is in sliding fit with the inner wall of the desulfurization filtrate tank, a moving block is arranged at the top of the filter screen, the inside of the moving block is in threaded fit with the outer surface of a screw rod, two ends of the screw rod are arranged at the top of the desulfurization filtrate tank through bearings, and the input end of the screw rod is connected with the output end of a servo motor; a first liquid inlet pipe is arranged above one side of the desulfurization filtrate tank, a first liquid outlet pipe is arranged below the desulfurization filtrate tank, and a first slag discharge pipe is arranged at the bottom of the desulfurization filtrate tank; the desulfurization filter tank opposite side top is equipped with the second feed liquor pipe, and the below is equipped with the second drain pipe, and the bottom is equipped with the second scum pipe, all be equipped with the valve on first feed liquor pipe, first drain pipe, first scum pipe, second feed liquor pipe, second drain pipe and the second scum pipe.
Preferably, the filtration and separation method of the reversible filtration system comprises the steps of:
step 4.1): the filtrate enters a desulfurization filtrate tank from a first liquid inlet pipe, liquid alkali is added into the desulfurization filtrate tank, carbon dioxide is introduced into the desulfurization filtrate tank to form calcium carbonate sediment, then a private motor is started to drive a screw rod to rotate, the moving block drives a filter screen to move towards the direction of the first liquid inlet pipe because the inside of the moving block is in threaded fit with the outer surface of the screw rod, in the moving process, the calcium carbonate sediment generated in the filtrate is intercepted to a position close to the position of the first slag discharge pipe, then a valve on a second liquid outlet pipe is opened, the filtrate is discharged from the second liquid outlet pipe and is fed into a sodium hypophosphite product production line, finally the valve on the first slag discharge pipe is opened, and the sediment can be washed out from the first slag discharge pipe after water is introduced;
step 4.2): filtrate enters into the desulfurization filtrate tank from the second feed liquor pipe, add liquid alkali and lets in carbon dioxide to desulfurization filtrate tank, in order to form the calcium carbonate sediment, then start private clothes motor, it drives the screw rod and rotates, because the movable block is inside to be in threaded fit with the screw rod surface, so the movable block drives the filter screen and moves towards the direction that second feed liquor pipe is located, in the removal in-process, the calcium carbonate sediment that produces in the filtrate is intercepted to be close to second scum pipe place, then open the valve on the first drain pipe, the filtrate is discharged from first drain pipe and is sent into sodium hypophosphite product production line, finally open the valve on the second scum pipe, can wash the sediment and go out from the second scum pipe after letting in water.
The application has the beneficial effects that:
1. the application establishes a multi-recovery refining system to separate sodium sulfate and hypophosphorous acid, and solves the problems of high content of hypophosphorous acid in sodium sulfate byproducts and difficult recovery.
2. According to the application, by utilizing the characteristics of sodium sulfate and the characteristics of high-temperature water loss and low-temperature crystallization, the freezing method is innovatively adopted to cool down so that water in the mother liquor enters sodium sulfate crystals to form dodecahydrate crystals, so that the hypophosphorous acid content of the mother liquor is improved, the hypophosphorous acid recovery treatment cost is reduced, the dodecahydrate sodium sulfate is recycled, and no waste is generated in the whole link.
3. The application uses lime for the desulfurization of hypophosphorous acid, solves the problem of high cost of treating sulfate by using barium hypophosphite in the past, and simultaneously can also be used for producing feed calcium, thereby changing waste into valuable.
4. According to the reversing filter system, calcium carbonate can be intercepted to one side in the moving process of the filter screen every time, and filtrate can be separated from the other side, so that calcium carbonate generated in the desulfurization filtrate tank can be continuously filtered and separated, and the separation efficiency is greatly improved.
5. The application can effectively recycle the hypophosphorous acid in the byproduct sodium sulfate for the production of sodium hypophosphite, and simultaneously improves the purity of the sodium sulfate to more than 99%, thereby achieving the purposes of solid waste utilization, clean production and production cost reduction; the method of the application can recycle sodium hypophosphite in byproduct sodium sulfate every year to produce 100-200 tons of sodium hypophosphite, and the market price of each ton of sodium hypophosphite is about 3 ten thousand yuan, thus the economic benefit is remarkable.
Drawings
FIG. 1 is a schematic flow chart of a method for refining and recovering sodium hypophosphite by-product sodium sulfate;
FIG. 2 is a schematic diagram of the internal structure of a reversible filtration system installed in a desulfurization filtrate tank.
Detailed Description
The application is described in further detail below with reference to the drawings and the specific examples.
As shown in figure 1, the method for refining and recovering sodium hypophosphite by using byproduct sodium sulfate comprises the following steps:
step 1): mixing water and crude sodium sulfate in a primary material tank, pumping the solid-liquid mixture into a dissolution and washing kettle, stirring for a period of time, and separating the feed liquid in a first centrifuge;
step 2): the filter residues obtained by separation of the first centrifugal machine enter a secondary material tank to be mixed with added water, then the mixture is pumped into an adjusting kettle, the pH value is kept to be neutral by adding alkali, after the mixture is stirred, reacted and aged for a period of time, the material liquid enters a second centrifugal machine to be separated, the separated finished product sodium sulfate enters a packaging workshop to be packaged, and the separated filtrate is returned to the primary material tank;
step 3): the filtrate separated by the first centrifugal machine is firstly accumulated in a primary filtrate tank, then enters a crystallization kettle, is cooled and crystallized by low-temperature water sent by a low-temperature water system, is centrifugally separated in a third centrifugal machine, and the obtained solid crystal is returned to a primary material tank, and mother liquor is sent to a desulfurization process;
step 4): the filtrate obtained by the desulfurization process enters a production line to produce sodium hypophosphite products;
step 5): and using the precipitate filtrate generated in the desulfurization process for producing a feed additive.
Preferably, in the step 1), after the solid-liquid mixture is pumped into the dissolution and washing kettle, the temperature is controlled to be more than 50 ℃, and the mixture is stirred for half an hour and then enters a first centrifuge for heat preservation and separation.
Preferably, in the step 2), the temperature of the adjusting kettle is kept above 50 ℃, the pH value is kept to be neutral by adding alkali, the stirring reaction is carried out for one hour, and the feed liquid enters a second centrifugal machine for separation, thus obtaining the finished sodium sulfate with the content of more than or equal to 99 percent.
Preferably, in the step 3), the filtrate separated by the first centrifuge enters a crystallization kettle, the filtrate is cooled to below 10 ℃ for crystallization by low temperature water of 7 ℃ sent by a low temperature water system, sodium sulfate decahydrate crystals are separated out, and then the filtrate is centrifugally separated in a third centrifuge.
Preferably, the filtrate is further used for promoting precipitation of sodium sulfate decahydrate crystallization by adding a certain amount of seed crystals in the crystallization process of the crystallization kettle.
Preferably, the desulfurization process in the step 3) and the step 4) is specifically: the mother liquor is sent to a desulfurization kettle, and then quicklime is added for reaction to form calcium sulfate precipitate, so that sulfate in the solution is removed, the mixed material is sent to a filter press for filter pressing, the filtrate is sent to a desulfurization filtrate tank and then to a sodium hypophosphite product production line, and the precipitate filtrate is sent to a feed additive production workshop to serve as a calcium source.
Preferably, if the calcium content in the filtrate in the desulfurization filtrate tank is greater than 0.1%, liquid alkali is added into the filtrate tank and carbon dioxide is introduced into the filtrate tank to form calcium carbonate precipitate, and the liquid calcium content in the filtrate is reduced until the liquid calcium content in the filtrate is less than 0.1%.
Preferably, a reversible filtration system 1 is arranged in the desulfurization filtrate tank and is used for filtering and separating the generated calcium carbonate.
Preferably, as shown in fig. 2, the reversible filtering system 1 includes a filter screen 1.1 vertically disposed in a desulfurization filtrate tank, the desulfurization filtrate tank has a square tank structure, the filter screen 1.1 has a rectangular plate structure and is slidably matched with an inner wall of the desulfurization filtrate tank, a moving block 1.2 is disposed at the top of the filter screen 1.1, the inside of the moving block 1.2 is in threaded fit with an outer surface of a screw 1.3, two ends of the screw 1.3 are mounted at the top of the desulfurization filtrate tank through bearings 1.4, and an input end of the screw 1.3 is connected with an output end of a servo motor 1.5; a first liquid inlet pipe 1.6 is arranged above one side of the desulfurization filtrate tank, a first liquid outlet pipe 1.7 is arranged below the desulfurization filtrate tank, and a first slag discharge pipe 1.8 is arranged at the bottom of the desulfurization filtrate tank; the desulfurization filtrate tank opposite side top is equipped with second feed liquor pipe 1.9, and the below is equipped with second drain pipe 1.10, and the bottom is equipped with second scum pipe 1.11, all be equipped with the valve on first feed liquor pipe 1.6, first drain pipe 1.7, first scum pipe 1.8, second feed liquor pipe 1.9, second drain pipe 1.10 and the second scum pipe 1.11.
Preferably, the filtration and separation method of the reversible filtration system comprises the steps of:
step 4.1): filtrate enters a desulfurization filtrate tank from a first liquid inlet pipe 1.6, liquid alkali is added into the desulfurization filtrate tank, carbon dioxide is introduced into the desulfurization filtrate tank to form calcium carbonate sediment, then a private motor 1.5 is started and drives a screw 1.3 to rotate, the interior of a moving block 1.2 is in threaded fit with the outer surface of the screw 1.3, so that the moving block 1.2 drives a filter screen 1.1 to move towards the direction of the first liquid inlet pipe 1.6, in the moving process, the calcium carbonate sediment generated in the filtrate is intercepted to a position close to the first slag discharge pipe 1.8, then a valve on a second liquid outlet pipe 1.10 is opened, the filtrate is discharged from the second liquid outlet pipe 1.10 and is fed into a sodium hypophosphite production line, finally the valve on the first slag discharge pipe 1.8 is opened, and the sediment can be washed out from the first slag discharge pipe 1.8 after water is introduced;
step 4.2): filtrate enters a desulfurization filtrate tank from a second liquid inlet pipe 1.9, liquid alkali is added into the desulfurization filtrate tank, carbon dioxide is introduced into the desulfurization filtrate tank to form calcium carbonate sediment, then a private motor 1.5 is started and drives a screw rod 1.3 to rotate, as the inside of a moving block 1.2 is in threaded fit with the outer surface of the screw rod 1.3, the moving block 1.2 drives a filter screen 1.1 to move towards the direction of the second liquid inlet pipe 1.9, in the moving process, the calcium carbonate sediment generated in the filtrate is intercepted to a position close to the position of the second slag discharge pipe 1.11, then a valve on a first liquid outlet pipe 1.7 is opened, the filtrate is discharged from the first liquid outlet pipe 1.7 and is fed into a sodium hypophosphite production line, finally the valve on the second slag discharge pipe 1.11 is opened, and the sediment can be washed out from the second slag discharge pipe 1.11 after water is introduced.
It can be seen that through the two steps, the movement process of the filter screen 1.1 can intercept the calcium carbonate to one side each time, and the other side can separate the filtrate, so that the calcium carbonate generated in the desulfurization filtrate tank can be continuously filtered and separated.
The following is a description of two specific embodiments:
embodiment case 1: 1000g of raw material sodium sulfate, 990g of sodium sulfate decahydrate returned by a system (solid treatment material returned by a third centrifugal machine) and 600g of water are stirred and mixed, the temperature is controlled to be more than 50 ℃ in a dissolution and washing kettle, the stirring is carried out for half an hour, the first centrifugal machine is used for heat preservation and separation, the raw material is washed again through a secondary material tank, and the raw material is separated through an adjusting kettle and a second centrifugal machine in sequence, so as to obtain 861g of anhydrous sodium sulfate, wherein the sodium sulfate content is 99.2%, the sodium hypophosphite monohydrate is 0.69%, and the hypophosphorous acid is 0.09%. Cooling the filtrate separated by the first centrifugal machine to below 10 ℃ for crystallization by low temperature water, centrifugally separating by a third centrifugal machine, sending the mother liquor obtained by separation into a crystallization mother liquor tank, then sending the mother liquor into a desulfurization kettle, adding 89g of lime, adjusting the pH value of the system to be neutral, stirring, reacting and aging for one hour, and press-filtering to obtain 202g of filter residue, wherein the filter residue contains 4.9% of sodium hypophosphite, 3.2% of calcium hypophosphite, 26.3% of calcium hydroxide, 26.8% of calcium sulfate and 34.4% of water, wherein the filter residue can be used for producing tricalcium phosphate as a feed additive, 642g of desulfurization filtrate collected by press-filtering contains 11.5% of sodium hypophosphite, 7.4% of calcium hypophosphite, 0.12% of calcium hydroxide, 0.16% of water and 80.7% of water, adding 13g of liquid alkali, and introducing corresponding carbon dioxide, adjusting the calcium content to be less than 0.1%, thus obtaining an aqueous solution with 20.8% of sodium hypophosphite, and the filter residue can be used for producing sodium hypophosphite.
Embodiment case 2: 1000g of raw material sodium sulfate, 1662g of sodium sulfate decahydrate returned by the system (solid treatment material returned by a third centrifugal machine) and 1000g of water are stirred and mixed, the temperature is controlled to be more than 50 ℃ in a dissolution and washing kettle, the stirring is carried out for half an hour, the first centrifugal machine is used for heat preservation and separation, the raw material is washed again through a secondary material tank, and the raw material is separated through an adjusting kettle and a second centrifugal machine in sequence, so as to obtain 861g of anhydrous sodium sulfate, wherein the sodium sulfate content is 99.6%, the sodium hypophosphite monohydrate is 0.38%, and the hypophosphorous acid is 0.06%. Cooling the filtrate separated by the first centrifugal machine to below 10 ℃ for crystallization by low temperature water, centrifugally separating by a third centrifugal machine, sending the mother liquor obtained by separation into a crystallization mother liquor tank, then sending the mother liquor into a desulfurization kettle, adding 91g of lime, adjusting the pH value of the system to be neutral, stirring, reacting and aging for one hour, and press-filtering to obtain 261g of filter residue, wherein the filter residue contains 4.75% of sodium hypophosphite, 0.38% of calcium hypophosphite, 20.85% of calcium hydroxide, 35% of calcium sulfate and 35% of water, wherein the filter residue can be used for producing tricalcium phosphate serving as a feed additive, 1031g of desulfurization filtrate collected by press-filtering, wherein the filtrate contains 11.64% of sodium hypophosphite, 0.95% of calcium hypophosphite, 0.12% of calcium hydroxide, 0.17% of calcium sulfate, 87.1% of water and 2.8g of supplementary caustic soda and is added with corresponding carbon dioxide, and the calcium content is adjusted to be less than 0.1%, so as to obtain an aqueous solution with 13.8% of sodium hypophosphite, and the aqueous solution can be used for producing sodium hypophosphite.
The above embodiments are merely preferred embodiments of the present application, and should not be construed as limiting the present application, and the embodiments and features of the embodiments of the present application may be arbitrarily combined with each other without collision. The protection scope of the present application is defined by the claims, and the protection scope includes equivalent alternatives to the technical features of the claims. I.e., equivalent replacement modifications within the scope of this application are also within the scope of the application.
Claims (2)
1. A method for refining and recovering sodium hypophosphite by using byproduct sodium sulfate is characterized by comprising the following steps: it comprises the following steps:
step 1): mixing water and crude sodium sulfate in a primary material tank, pumping the solid-liquid mixture into a dissolution and washing kettle, stirring for a period of time, and separating the feed liquid in a first centrifuge;
step 2): the filter residues obtained by separation of the first centrifugal machine enter a secondary material tank to be mixed with added water, then the mixture is pumped into an adjusting kettle, the pH value is kept to be neutral by adding alkali, after the mixture is stirred, reacted and aged for a period of time, the material liquid enters a second centrifugal machine to be separated, the separated finished product sodium sulfate enters a packaging workshop to be packaged, and the separated filtrate is returned to the primary material tank;
step 3): the filtrate separated by the first centrifugal machine is firstly accumulated in a primary filtrate tank, then enters a crystallization kettle, is cooled and crystallized by low-temperature water sent by a low-temperature water system, is centrifugally separated in a third centrifugal machine, and the obtained solid crystal is returned to a primary material tank, and mother liquor is sent to a desulfurization process;
step 4): the filtrate obtained by the desulfurization process enters a production line to produce sodium hypophosphite products;
step 5): the sediment filtrate produced in the desulfurization procedure is used for producing feed additives;
in the step 1), after the solid-liquid mixture is pumped into a dissolution and washing kettle, controlling the temperature to be above 50 ℃, stirring for half an hour, and then entering a first centrifuge for heat preservation and separation;
in the step 2), the temperature of the kettle is regulated to be more than 50 ℃, the pH value is regulated to be neutral by adding alkali, the mixture is stirred, reacted and aged for one hour, and the feed liquid enters a second centrifuge to be separated, so that the finished sodium sulfate with the content of more than or equal to 99% is obtained;
in the step 3), the filtrate separated by the first centrifugal machine enters a crystallization kettle, the filtrate is cooled to below 10 ℃ for crystallization by low temperature water of 7 ℃ sent by a low temperature water system, sodium sulfate decahydrate crystals are separated out, and then centrifugal separation is carried out in a third centrifugal machine;
the desulfurization process in the step 3) and the step 4) is specifically as follows: the mother solution is sent to a desulfurization kettle, then quicklime is added for reaction to form calcium sulfate precipitate, so that sulfate in the solution is removed, the mixed material is sent to a filter press for filter pressing, the filtrate is sent to a desulfurization filtrate tank and then to a sodium hypophosphite product production line, and the precipitate filtrate is sent to a feed additive production workshop to be used as a calcium source;
if the content of calcium in the filtrate in the desulfurization filtrate tank is more than 0.1%, adding liquid alkali into the filtrate tank and introducing carbon dioxide to form calcium carbonate precipitate, and reducing the content of liquid calcium in the filtrate until the content of liquid calcium in the filtrate is less than 0.1%;
a reversible filtering system (1) is arranged in the desulfurization filtrate tank and is used for filtering and separating generated calcium carbonate;
the reversible filtering system (1) comprises a filter screen (1.1) vertically arranged in a desulfurization filtrate tank, the desulfurization filtrate tank is of a square tank body structure, the filter screen (1.1) is of a rectangular plate-shaped structure and is in sliding fit with the inner wall of the desulfurization filtrate tank, a moving block (1.2) is arranged at the top of the filter screen (1.1), the inside of the moving block (1.2) is in threaded fit with the outer surface of a screw rod (1.3), two ends of the screw rod (1.3) are arranged at the top of the desulfurization filtrate tank through bearings (1.4), and the input end of the screw rod (1.3) is connected with the output end of a servo motor (1.5); a first liquid inlet pipe (1.6) is arranged above one side of the desulfurization filtrate tank, a first liquid outlet pipe (1.7) is arranged below the desulfurization filtrate tank, and a first slag discharge pipe (1.8) is arranged at the bottom of the desulfurization filtrate tank; a second liquid inlet pipe (1.9) is arranged above the other side of the desulfurization filtrate tank, a second liquid outlet pipe (1.10) is arranged below the desulfurization filtrate tank, a second slag discharge pipe (1.11) is arranged at the bottom of the desulfurization filtrate tank, and valves are arranged on the first liquid inlet pipe (1.6), the first liquid outlet pipe (1.7), the first slag discharge pipe (1.8), the second liquid inlet pipe (1.9), the second liquid outlet pipe (1.10) and the second slag discharge pipe (1.11);
the filtering and separating method of the reversible filtering system comprises the following steps:
step 4.1): filtrate enters a desulfurization filtrate tank from a first liquid inlet pipe (1.6), liquid alkali is added into the desulfurization filtrate tank, carbon dioxide is introduced into the desulfurization filtrate tank to form calcium carbonate sediment, then a servo motor (1.5) is started and drives a screw rod (1.3) to rotate, the interior of a moving block (1.2) is in threaded fit with the outer surface of the screw rod (1.3), so that the moving block (1.2) drives a filter screen (1.1) to move towards the direction of the first liquid inlet pipe (1.6), in the moving process, the calcium carbonate sediment generated in the filtrate is intercepted to a position close to the position of the first liquid outlet pipe (1.8), then a valve on a second liquid outlet pipe (1.10) is opened, the filtrate is discharged from the second liquid outlet pipe (1.10) and is fed into a sodium hypophosphite product production line, and finally the valve on the first liquid outlet pipe (1.8) is opened, and the sediment can be washed out from the first liquid outlet pipe (1.8) after water is introduced;
step 4.2): filtrate enters a desulfurization filtrate tank from a second liquid inlet pipe (1.9), liquid alkali is added into the desulfurization filtrate tank, carbon dioxide is introduced into the desulfurization filtrate tank to form calcium carbonate sediment, then a servo motor (1.5) is started, the servo motor drives a screw rod (1.3) to rotate, as the inside of a moving block (1.2) is in threaded fit with the outer surface of the screw rod (1.3), the moving block (1.2) drives a filter screen (1.1) to move towards the direction of the second liquid inlet pipe (1.9), in the moving process, the calcium carbonate sediment generated in the filtrate is intercepted to a position close to the position of the second liquid inlet pipe (1.11), then a valve on a first liquid outlet pipe (1.7) is opened, the filtrate is discharged from the first liquid outlet pipe (1.7) and is fed into a sodium hypophosphite product production line, and finally the valve on the second liquid outlet pipe (1.11) is opened, and sediment can be flushed out from the second liquid outlet pipe (1.11) after water is introduced.
2. The method for refining and recovering sodium hypophosphite by using sodium sulfate byproduct according to claim 1, which is characterized in that: in the crystallization process of the filtrate in the crystallization kettle, a certain amount of seed crystals are added to promote precipitation of sodium sulfate decahydrate crystals.
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