CN111285507A - Waste residue and waste water reutilization method and device for chlor-alkali plant - Google Patents
Waste residue and waste water reutilization method and device for chlor-alkali plant Download PDFInfo
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- CN111285507A CN111285507A CN202010238118.3A CN202010238118A CN111285507A CN 111285507 A CN111285507 A CN 111285507A CN 202010238118 A CN202010238118 A CN 202010238118A CN 111285507 A CN111285507 A CN 111285507A
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- potassium chloride
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- 238000000034 method Methods 0.000 title claims abstract description 34
- 239000002351 wastewater Substances 0.000 title claims abstract description 34
- 239000002699 waste material Substances 0.000 title claims abstract description 24
- 239000003513 alkali Substances 0.000 title claims description 23
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims abstract description 88
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims abstract description 64
- 239000001103 potassium chloride Substances 0.000 claims abstract description 44
- 235000011164 potassium chloride Nutrition 0.000 claims abstract description 44
- 239000012267 brine Substances 0.000 claims abstract description 38
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims abstract description 38
- 239000002002 slurry Substances 0.000 claims abstract description 34
- 239000002893 slag Substances 0.000 claims abstract description 27
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 claims abstract description 22
- 229910052939 potassium sulfate Inorganic materials 0.000 claims abstract description 22
- 235000011151 potassium sulphates Nutrition 0.000 claims abstract description 22
- 239000002253 acid Substances 0.000 claims abstract description 14
- 150000003839 salts Chemical class 0.000 claims abstract description 13
- 229910002651 NO3 Inorganic materials 0.000 claims abstract description 11
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000012528 membrane Substances 0.000 claims description 75
- 239000000919 ceramic Substances 0.000 claims description 51
- 239000007788 liquid Substances 0.000 claims description 51
- 238000000926 separation method Methods 0.000 claims description 25
- 239000006249 magnetic particle Substances 0.000 claims description 22
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 claims description 20
- 239000003456 ion exchange resin Substances 0.000 claims description 20
- 229920003303 ion-exchange polymer Polymers 0.000 claims description 20
- 239000002245 particle Substances 0.000 claims description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- 238000001728 nano-filtration Methods 0.000 claims description 18
- VKJKEPKFPUWCAS-UHFFFAOYSA-M potassium chlorate Chemical compound [K+].[O-]Cl(=O)=O VKJKEPKFPUWCAS-UHFFFAOYSA-M 0.000 claims description 18
- 238000005406 washing Methods 0.000 claims description 18
- 230000035699 permeability Effects 0.000 claims description 16
- 230000008569 process Effects 0.000 claims description 14
- 239000011148 porous material Substances 0.000 claims description 13
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 claims description 12
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 11
- 238000001556 precipitation Methods 0.000 claims description 11
- 239000000243 solution Substances 0.000 claims description 11
- 239000000706 filtrate Substances 0.000 claims description 10
- 238000001914 filtration Methods 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 9
- 239000006148 magnetic separator Substances 0.000 claims description 8
- 239000012466 permeate Substances 0.000 claims description 8
- 238000004064 recycling Methods 0.000 claims description 8
- 238000009295 crossflow filtration Methods 0.000 claims description 7
- 238000002156 mixing Methods 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 239000000725 suspension Substances 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 4
- 238000003825 pressing Methods 0.000 claims description 3
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 2
- 239000000460 chlorine Substances 0.000 claims description 2
- 229910052801 chlorine Inorganic materials 0.000 claims description 2
- 239000012141 concentrate Substances 0.000 claims description 2
- 239000002244 precipitate Substances 0.000 claims description 2
- 239000010908 plant waste Substances 0.000 claims 2
- 230000002378 acidificating effect Effects 0.000 abstract description 6
- 239000002994 raw material Substances 0.000 abstract description 3
- 229910052602 gypsum Inorganic materials 0.000 abstract description 2
- 239000010440 gypsum Substances 0.000 abstract description 2
- 239000000084 colloidal system Substances 0.000 description 17
- 230000004907 flux Effects 0.000 description 9
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 6
- 229910017604 nitric acid Inorganic materials 0.000 description 6
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 5
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical group [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 5
- 239000000920 calcium hydroxide Substances 0.000 description 5
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 5
- 239000012065 filter cake Substances 0.000 description 5
- 238000011084 recovery Methods 0.000 description 5
- 238000005868 electrolysis reaction Methods 0.000 description 4
- 239000012530 fluid Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000002105 nanoparticle Substances 0.000 description 4
- 239000005997 Calcium carbide Substances 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000011001 backwashing Methods 0.000 description 2
- 229910001424 calcium ion Inorganic materials 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005553 drilling Methods 0.000 description 2
- 230000000149 penetrating effect Effects 0.000 description 2
- 229920000915 polyvinyl chloride Polymers 0.000 description 2
- 239000004800 polyvinyl chloride Substances 0.000 description 2
- 229940072033 potash Drugs 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Substances [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- 235000015320 potassium carbonate Nutrition 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 1
- 102000015863 Nuclear Factor 90 Proteins Human genes 0.000 description 1
- 108010010424 Nuclear Factor 90 Proteins Proteins 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000013065 commercial product Substances 0.000 description 1
- 230000000382 dechlorinating effect Effects 0.000 description 1
- 238000006298 dechlorination reaction Methods 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 229910001425 magnesium ion Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005374 membrane filtration Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000009991 scouring Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/42—Treatment of water, waste water, or sewage by ion-exchange
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/48—Treatment of water, waste water, or sewage with magnetic or electric fields
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
- C02F1/5245—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents using basic salts, e.g. of aluminium and iron
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/101—Sulfur compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/12—Halogens or halogen-containing compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/16—Nitrogen compounds, e.g. ammonia
- C02F2101/163—Nitrates
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/20—Heavy metals or heavy metal compounds
- C02F2101/203—Iron or iron compound
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- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention relates to a method for removing sulfate radicals in a potassium chloride brine system and a method for comprehensively utilizing and treating acid, alkaline waste brine, carbide slag slurry and other wastes discharged from a factory. By adopting the method, the potassium chloride brine, the carbide slag slurry, the acidic wastewater and the alkaline wastewater are fully utilized, waste is changed into valuable, the potassium sulfate and the carbide slag slurry are converted into calcium sulfate, and all potassium chloride is returned to the salt dissolving system to be fully recycled. The method solves the problem of environment-friendly disposal of the nitrate-rich brine and the carbide slag, completely recovers the potassium chloride raw material, can produce calcium sulfate gypsum products, and achieves the purposes of resource treatment and zero emission.
Description
Technical Field
The invention relates to a method for removing sulfate radicals in a potassium chloride brine system and a method for comprehensively utilizing and treating acid, alkaline waste brine, carbide slag slurry and other wastes discharged from a factory.
Background
In the chemical process of chlor-alkali, the production of ionic membrane potash can carry out electrolysis treatment on potassium chloride brine, and low-concentration potassium chloride brine can be generated after electrolysis, commonly called weak brine, and the ionic membrane potash comprises the following main components: 120-310g/L potassium chloride, 0.5-13g/L potassium sulfate and 2-20g/L potassium chlorate; in addition, a chlor-alkali plant usually generates a large amount of carbide slag slurry in the production of polyvinyl chloride, and in the purification of potassium chloride brine, the ion exchange resin is usually used for deep hardness removal treatment, so that a large amount of acidic wastewater is generated in the regeneration of the ion exchange resin.
The treatment and discharge of potassium chloride brine, carbide slag slurry, acidic wastewater and alkaline wastewater are important problems existing in chlor-alkali chemical industry production enterprises, the simple discharge of the wastewater and the waste slag obviously seriously pollutes the environment, if the wastewater and the waste slag are treated, the amount is large, the treatment cost is high, the energy consumption is high, other media are required to be added, the cost is high, the equipment investment is large, and the industrial popularization and application cannot be realized.
Disclosure of Invention
The invention aims to provide an integrated treatment process aiming at acid-base wastewater generated in the processes of potassium chloride weak brine, electric slag slurry and resin washing in the existing chlor-alkali plant, and the integrated treatment process is used for treating the wastewater based on the characteristics of the wastewater so as to achieve the advantages of mutual synergy and resource recycling.
In order to achieve the above object, the processing scheme of the present invention is as follows:
the waste residue and waste water reusing method for chlor-alkali plant includes the following steps:
step 1, performing nanofiltration separation treatment on potassium chloride brine containing sulfate ions to obtain a concentrated solution and a permeate;
step 2, mixing the concentrated solution obtained in the step 1 with carbide slag slurry and acid washing wastewater of ion exchange resin to generate calcium sulfate precipitate;
and 3, carrying out solid-liquid separation on the suspension obtained in the step 2 to obtain calcium sulfate.
In one embodiment, the permeate in the step 1, the filtrate obtained by solid-liquid separation in the step 3, or the alkaline washing wastewater of the ion exchange resin is sent to a salt dissolving process for recycling.
In one embodiment, the composition of the potassium chloride brine containing sulfate ions in step 1 comprises: 120-310g/L potassium chloride, 0.5-13g/L potassium sulfate and 0-20 g/L potassium chlorate.
In one embodiment, the composition of the concentrate obtained in step 1 comprises: 120-310g/L of potassium chloride, 25-50 g/L of potassium sulfate and 0-20 g/L of potassium chlorate; the composition of the permeate obtained included: 120-310g/L potassium chloride, 0.005-0.5 g/L potassium sulfate, and 0-20 g/L potassium chlorate.
In one embodiment, in the step 2, the solid content of the carbide slag slurry is 10-15%.
In one embodiment, the pH of the waste water from the acid washing of the ion exchange resin in step 2 is 1-5.
In one embodiment, in the step 2, the weight ratio is: nitrate-rich brine: waste acid water: carbide slag slurry = 1: 0.1-0.5: 0.2 to 0.8.
In one embodiment, in the step 3, the filtrate obtained by the solid-liquid separation contains: 60-180 g/L of potassium chloride, 1-5 g/L of potassium sulfate and 0-12 g/L of potassium chlorate.
In one embodiment, in the step 3, a tubular ceramic membrane is adopted in the solid-liquid separation process, the pore diameter range of the tubular ceramic membrane is 50-200nm, nitric acid modified magnetic ferroferric oxide particles are required to be added before the suspension is subjected to solid-liquid separation, the surface potential of the magnetic ferroferric oxide particles is controlled to be +5mV to +15mV, and the addition amount is 0.2-0.5 wt%.
In one embodiment, the tubular ceramic membrane adopts a cross-flow filtration mode, a magnetic permeability detector is further arranged at the outlet end of the pipeline and used for detecting the magnetic permeability of liquid in the pipeline, and when the magnetic permeability is smaller than a threshold value, solid-liquid separation is stopped and the tubular ceramic membrane is washed; and magnetic ferroferric oxide particles are recovered by a magnetic separator under the magnetic permeability detector, and the feed liquid at the outlet end of the pipeline of the tubular ceramic membrane returns to the feed liquid inlet of the tubular ceramic membrane for secondary filtration.
Chlorine alkali factory waste residue waste water reuse device includes:
the nanofiltration membrane is used for carrying out nanofiltration separation treatment on the potassium chloride brine containing sulfate ions;
the slurry tank is used for storing carbide slag slurry;
the precipitation reaction tank is respectively connected to the interception side of the nanofiltration membrane, the slurry tank and the ion exchange resin column and is used for mixing the obtained concentrated solution with the carbide slag slurry and the acid washing wastewater of the ion exchange resin to generate calcium sulfate precipitation;
and the solid-liquid separator is connected with the precipitation reaction tank and is used for carrying out solid-liquid separation treatment on the feed liquid after the precipitation reaction and intercepting the calcium sulfate.
In one embodiment, the permeate side of the nanofiltration membrane, the ion exchange resin column and the filtrate side of the solid-liquid separator are connected to the salt dissolving tank.
In one embodiment, the solid-liquid separator adopts a tubular ceramic membrane; a magnetic particle feeder is also arranged at a feed liquid inlet of the tubular ceramic membrane and used for feeding magnetic particles into the feed liquid entering the tubular ceramic membrane on line, and a magnetic conductivity detector is also arranged at a feed liquid outlet at the interception side of the tubular ceramic membrane and used for detecting the magnetic conductivity in the intercepted liquid; a magnetic separator is arranged at the downstream side of the magnetic conductivity detector and is used for recovering magnetic particles in a magnetic manner; and a feed liquid outlet on the interception side of the tubular ceramic membrane is connected to a slurry tank.
In one embodiment, the tubular ceramic membrane has an average pore size in the range of 50 to 200 nm.
In one embodiment, a plate-and-frame filter is further arranged on the liquid-retaining side of the tubular ceramic membrane and is used for performing filter pressing on calcium sulfate in the liquid-retaining solution.
Advantageous effects
By adopting the method, the potassium chloride brine, the carbide slag slurry, the acidic wastewater and the alkaline wastewater are fully utilized, waste is changed into valuable, the potassium sulfate and the carbide slag slurry are converted into calcium sulfate, and all potassium chloride is returned to the salt dissolving system to be fully recycled. The method solves the problem of environment-friendly disposal of the nitrate-rich brine and the carbide slag, completely recovers the potassium chloride raw material, can produce calcium sulfate gypsum products, and achieves the purposes of resource treatment and zero emission.
Drawings
FIG. 1 is a flow chart of a method provided by the present invention;
FIG. 2 is a diagram of an apparatus provided by the present invention;
FIG. 3 is a diagram of equipment associated with a ceramic membrane filter;
FIG. 4 is a flux curve for a tubular ceramic membrane operating process;
FIG. 5 is a comparison of flux recovery for tubular ceramic membranes;
wherein, 1, a nanofiltration membrane; 2. a slurry tank; 3. ion exchange resin column; 4. a precipitation reaction tank; 5. a solid-liquid separator; 6. a plate frame filter; 7. a magnetic permeability detector; 8. a magnetic separator; 9. a magnetic particle feeder.
Detailed Description
In general, in a chlor-alkali plant, during the process of preparing potassium hydroxide by potassium chloride electrolysis, a potassium chloride weak brine is generated, and after dechlorination treatment, the water quality of the potassium chloride brine is generally as follows: 120-310g/L of potassium chloride, 0.5-13g/L of potassium sulfate and 1-20 g/L of potassium chlorate; or potassium chloride refined brine in the production of potassium chloride; one of the main features is the presence of sulfate ions.
Meanwhile, a large number of calcium carbide slurry is also generated in a large polychlorinated alkali factory in a working section for producing polyvinyl chloride, the calcium carbide slurry is residue after reaction of calcium carbide and water, the main component is calcium hydroxide, and the solid content by weight is 10-15%;
in a chlor-alkali plant, in order to perform concentration hardness removal treatment on brine, ion exchange treatment is performed on multivalent ions such as calcium and magnesium ions by using an ion exchange resin, and in order to regenerate the ion exchange resin, acid washing water (pH is 1-5) and alkali washing water (pH is 8-11) are generated;
aiming at the above waste water and wastes, the process adopted by the invention is detailed as follows:
firstly, nanofiltration treatment is carried out on potassium chloride brine by adopting a nanofiltration membrane, divalent ions can be intercepted by nanofiltration, so that sulfate ions are intercepted, and brine rich in potassium sulfate (also called nitrate-rich brine) and penetrating fluid of the nanofiltration membrane (also called nitrate-poor brine) can be obtained; the nitrate-poor water is sent to a salt dissolving working section to be used as salt dissolving water; the device used by the nanofiltration unit is a commercial product, such as a membrane separation device of products with the Dow company brand of NF90, the GE company brand of DL and the Dongli company brand of SU 610; the pressure of membrane separation is 1.0-3.5 Mpa, and the temperature is 35-40 ℃;
obtaining a nitrate-rich brine containing: 120-310g/L of potassium chloride, 25-50 g/L of potassium sulfate and 1-20 g/L of potassium chlorate; the obtained nitrate-depleted water contains: 120-310g/L of potassium chloride, 0.005-0.5 g/L of potassium sulfate and 1-20 g/L of potassium chlorate;
next, since the nitrate-rich brine contains sulfate ions obtained by concentration, the carbide slag slurry mainly contains calcium hydroxide, and the pH of the resin washing water is acidic, after the three are mixed, the resin washing water can be used for dissolving the calcium hydroxide, the calcium hydroxide further reacts with the sulfate ions to generate calcium sulfate, and the calcium sulfate is separated by a solid-liquid separation method. Meanwhile, the filtrate obtained after solid-liquid separation, the nitrate-poor brine and the alkaline washing water of the ion exchange resin can be sent to a salt dissolving section of a chlor-alkali plant for continuous treatment. In a preferred embodiment, the weight ratio is as follows: nitrate-rich brine: waste acid water: carbide slag slurry = 1: 0.1-0.5: 0.2 to 0.8; the filtrate obtained after precipitation and solid-liquid separation mainly contains: comprises the following components: 60-180 g/L of potassium chloride, 1-5 g/L of potassium sulfate and 1-12 g/L of potassium chlorate.
In the solid-liquid separation process, the calcium sulfate colloid generated by the precipitation reaction is mainly filtered, so that a tubular ceramic membrane can be adopted for filtering treatment, and a cross-flow filtering mode is usually adopted in engineering; in addition, the generated calcium sulfate colloid has small particle size, so that the generated calcium sulfate colloid is easy to block membrane pores of the ceramic membrane to cause the blockage in the pores, and the flux of the ceramic membrane is difficult to recover (even if backwashing is used, the pores cannot be effectively blockedFine colloidal particle removal of); therefore, the method can be used for adding the nitric acid modified magnetic ferroferric oxide particles into the calcium sulfate colloid-containing material before ceramic membrane filtration, and the main step is to add Fe3O4The particles are soaked in nitric acid solution due to the presence of Fe3O4After the surface of the calcium sulfate colloid is treated by the nitric acid solution, the surface potential of the calcium sulfate colloid can be changed into positive, so that the calcium sulfate colloid has positive charges, and the surface of the calcium sulfate colloid has negative charges (particularly under the condition of excessive sulfate ions), so that the calcium sulfate colloid is coated on the Fe with the positive charges3O4Larger colloid particles are formed on the particles, so that the problem of hole blockage caused by small particles drilling into film holes is avoided; fe in the above step3O4The size of the particles can be controlled between 100 and 200nm, and the surface potential can be controlled between +5mV and +15 mV; fe3O4The addition amount of the particles can be controlled to be 0.2-0.5wt%, and the average pore diameter of the tubular ceramic membrane can be 50-200 nm.
Meanwhile, when the tubular ceramic membrane is used for filtering, fluid flows in the pipeline, and along with the continuous discharge of penetrating fluid from the pipe wall, the flow at the tail end can be reduced, so that the scouring force of the fluid is reduced, colloid particles can form a thick filter cake layer at the tail end, and if the filter cake continuously grows and is not flushed out in time, the blockage in the cross-flow pipeline is easily caused, so that the whole ceramic membrane pipe is scrapped. Therefore, a magnetic permeability detector for detecting the magnetic permeability of the pipeline liquid is arranged at the outlet end of the channel of the tubular ceramic membrane, the value of the magnetic permeability of the liquid can be obtained online in real time, when the pipeline is blocked, filter cake particles formed by mixing a part of magnetic particles and colloid can be intercepted, the amount of the discharged magnetic particles is reduced, the magnetic permeability is in a direct proportion relation with the amount of the magnetic particles, the value on the magnetic permeability instrument is reduced, when the magnetic permeability is smaller than a threshold value, the filter cake inside is considered to be blocked, the whole membrane tube can be scrapped possibly, and at the moment, after the channel of the membrane tube is restored, the solid-liquid separation operation can be carried out again. Therefore, the magnetic particles play a dual role, not only can play a role in adsorbing negative electricity colloid, but also play a role in detecting and indicating the internal condition of the pipeline; meanwhile, a magnetic separator is arranged at the downstream side of the magnetic permeability instrument and used for recovering magnetic particles in a magnetic manner; returning the cross-flow feed liquid to the feed liquid inlet of the tubular ceramic membrane for reuse; in most cases, when the tubular ceramic membrane is subjected to cross-flow filtration, a circulation mode is adopted, so that the concentration in the raw material liquid tank is higher and higher, and after the magnetic particles are recovered by the magnetic separator, the magnetic particles are added in an online adding mode, so that the concentration of the magnetic particles entering the tubular ceramic membrane during cross-flow filtration can be kept at a constant value, and the error of a detector in the judgment process of a detection threshold value caused by the fact that the concentration of the particles is improved after the particles are brought in by the backflow of cross-flow feed liquid can be avoided.
Example 1
Dechlorinating light salt brine generated in the potassium chloride electrolysis process to obtain salt brine with water quality as follows: 150g/L potassium chloride, 5g/L potassium sulfate and 10g/L potassium chlorate, filtering by a nanofiltration membrane, intercepting the potassium sulfate, wherein the operating pressure of the nanofiltration membrane is 1.5MPa, and obtaining nitrate-rich saline (140 g/L potassium chloride, 45g/L potassium sulfate and 10g/L potassium chlorate) and nitrate-poor saline (160 g/L potassium chloride, 0.01g/L potassium sulfate and 10g/L potassium chlorate); meanwhile, in the regeneration process of the ion exchange resin, acid washing wastewater with pH of 2-3 and carbide slag slurry (solid content of 12%) are generated, and nitrate-rich brine in percentage by weight is prepared by the following steps: waste acid water: carbide slag slurry = 1: 0.4: 0.3, under an acidic condition, enabling calcium hydroxide to generate calcium ions, then reacting with sulfate radicals to generate calcium sulfate, performing cross-flow filtration on the generated suspension through a tubular ceramic membrane with the average pore diameter of 200nm under the condition of 2m/s, wherein the diameter of a channel of the tubular membrane is 2mm to obtain calcium sulfate slurry, returning feed liquid discharged from the interception side of the ceramic membrane in the cross-flow filtration process to the ceramic membrane again for filtration, and performing filter pressing on the calcium sulfate slurry in a plate-and-frame filtration mode to obtain calcium sulfate. Mixing the obtained ceramic membrane filtrate, the alkaline washing wastewater of the ion exchange resin and the nitrate-poor water, and then sending the mixture to a salt dissolving process.
Example 2
On the basis of example 1, before filtering with a tubular ceramic membrane, 0.5g/L of ordinary ferroferric oxide nanoparticles and nitric acid-modified ferroferric oxide nanoparticles (the average diameter is about 100nm, which is obtained by soaking the ferroferric oxide nanoparticles in 2mol/L of nitric acid solution for 2 hours, taking out, washing and drying) are respectively added into the precipitated suspension on line. And after cross-flow filtration, the magnetic particles are recovered again through the magnetic separator, and the concentration of the nano particles entering the tubular ceramic membrane is kept constant.
In the above examples, the main ion contents in the obtained ceramic membrane filtrate were: 140g/L of potassium chloride, 5g/L of potassium sulfate and 10g/L of potassium chlorate; the brine fed into the salt dissolving process mainly comprises: 80g/L of potassium chloride, 4.5g/L of potassium sulfate and 5g/L of potassium chlorate.
The flux decay curve of the ceramic membrane during operation in the above examples is shown in fig. 4. It can be seen from the figure that when the nitric acid modified magnetic particles with positive charges are adopted, the calcium sulfate colloid can be coated on the surfaces of the magnetic particles through electrostatic action due to the surface charge action of the magnetic particles, so that the calcium sulfate colloid is prevented from being drilled into membrane pores of a ceramic membrane, the blockage in the pores of the membrane is reduced, and the flux attenuation is delayed; compared with the method without adding the magnetic particles, the flux of the magnetic particles directly adopted is not greatly different.
After a filtration experiment of 100min, the tubular ceramic membrane is subjected to cross-flow washing for 20min in a channel by pure water under the condition of 4m/s, a filter cake layer is removed, and the flux recovery rate is inspected to judge the blocking pollution condition in the membrane pores. The flux recovery rates after the above experimental groups were subjected to the overshoot are shown below, and the recovery rate pairs are shown in fig. 5:
as can be seen from the above table, when positively charged magnetic particles are used, they can form a coating with calcium sulfate colloid, so that membrane pollution caused by the colloid particles drilling into membrane pores of the ceramic membrane is avoided, and a better recovery rate can be achieved by cross-flow washing. And a backwashing mode can be adopted, so that the membrane flux can be recovered more effectively.
Claims (10)
1. The waste residue and waste water reuse method for the chlor-alkali plant is characterized by comprising the following steps:
step 1, performing nanofiltration separation treatment on potassium chloride brine containing sulfate ions to obtain a concentrated solution and a permeate;
step 2, mixing the concentrated solution obtained in the step 1 with carbide slag slurry and acid washing wastewater of ion exchange resin to generate calcium sulfate precipitate;
and 3, carrying out solid-liquid separation on the suspension obtained in the step 2 to obtain calcium sulfate.
2. The method for recycling waste residue and waste water of a chlor-alkali plant according to claim 1, characterized in that in one embodiment, the permeate of step 1, the filtrate obtained by solid-liquid separation of step 3, or the alkali wash waste water of ion exchange resin is sent to a salt dissolving process for recycling;
in one embodiment, the composition of the potassium chloride brine containing sulfate ions in step 1 comprises: 120-310g/L potassium chloride, 0.5-13g/L potassium sulfate and 0-20 g/L potassium chlorate.
3. The method for recycling waste residue and water of chlor-alkali plant of claim 1, wherein in one embodiment, said concentrate obtained in step 1 comprises: 120-310g/L of potassium chloride, 25-50 g/L of potassium sulfate and 0-20 g/L of potassium chlorate; the composition of the permeate obtained included: 120-310g/L of potassium chloride, 0.005-0.5 g/L of potassium sulfate and 0-20 g/L of potassium chlorate;
in one embodiment, in the step 2, the solid content of the carbide slag slurry is 10-15%;
in one embodiment, the pH of the waste water from the acid washing of the ion exchange resin in step 2 is 1-5.
4. The method for recycling waste residue and water of chlor-alkali plant of claim 1, wherein in one embodiment, said step 2 comprises the following steps: nitrate-rich brine: waste acid water: carbide slag slurry = 1: 0.1-0.5: 0.2 to 0.8;
in one embodiment, in the step 3, the filtrate obtained by the solid-liquid separation contains: 60-180 g/L of potassium chloride, 1-5 g/L of potassium sulfate and 0-12 g/L of potassium chlorate.
5. The method for recycling waste residue and wastewater of a chlor-alkali plant as recited in claim 1, wherein in said step 3, a tubular ceramic membrane is used for solid-liquid separation, the pore size of said tubular ceramic membrane is in the range of 50-200nm, and nitric acid-modified magnetic ferroferric oxide particles are added before solid-liquid separation of the suspension, the surface potential of the magnetic ferroferric oxide particles is controlled between +5mV and +15mV, and the addition amount is 0.2-0.5 wt%.
6. The method of claim 5, wherein in one embodiment, the tubular ceramic membrane is in a cross-flow filtration mode, a magnetic permeability detector is further disposed at the outlet end of the pipeline for detecting the magnetic permeability of the liquid in the pipeline, and when the magnetic permeability is less than a threshold value, the solid-liquid separation is stopped and the tubular ceramic membrane is washed; and magnetic ferroferric oxide particles are recovered by a magnetic separator under the magnetic permeability detector, and the feed liquid at the outlet end of the pipeline of the tubular ceramic membrane returns to the feed liquid inlet of the tubular ceramic membrane for secondary filtration.
7. Chlorine alkali factory waste residue waste water reuse device, its characterized in that includes:
a nanofiltration membrane (1) used for carrying out nanofiltration separation treatment on the potassium chloride brine containing sulfate ions;
the slurry tank (2) is used for storing carbide slag slurry;
the precipitation reaction tank (4) is respectively connected to the interception side of the nanofiltration membrane (1), the slurry tank (2) and the ion exchange resin column (3) and is used for mixing the obtained concentrated solution with the carbide slag slurry and the acid washing wastewater of the ion exchange resin to generate calcium sulfate precipitation;
and the solid-liquid separator (5) is connected with the precipitation reaction tank (4) and is used for carrying out solid-liquid separation treatment on the feed liquid after the precipitation reaction and intercepting calcium sulfate.
8. The waste residue and wastewater recycling device of chlor-alkali plant as claimed in claim 7, wherein in one embodiment, the permeate side of said nanofiltration membrane (1), the filtrate side of said ion exchange resin column (3) and said solid-liquid separator (5) are connected to a salt dissolving tank.
9. The chlor-alkali plant waste residue wastewater reuse apparatus of claim 7, wherein in one embodiment, said solid-liquid separator (5) employs tubular ceramic membranes; a magnetic particle feeder (9) is also arranged at the feed liquid inlet of the tubular ceramic membrane and is used for feeding magnetic particles into the feed liquid entering the tubular ceramic membrane on line, and a magnetic conductivity detector is also arranged at the feed liquid outlet of the interception side of the tubular ceramic membrane and is used for detecting the magnetic conductivity in the interception liquid; a magnetic separator is arranged at the downstream side of the magnetic conductivity detector and is used for recovering magnetic particles in a magnetic manner; the feed liquid outlet on the interception side of the tubular ceramic membrane is connected to a slurry tank (2).
10. The chlor-alkali plant waste residue wastewater reuse apparatus of claim 9, wherein in one embodiment, said tubular ceramic membranes have an average pore size ranging from 50 to 200 nm; in one embodiment, a plate-and-frame filter is further arranged on the liquid-retaining side of the tubular ceramic membrane and is used for performing filter pressing on calcium sulfate in the liquid-retaining solution.
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