CN114409141A - Method for hardness removal of coal gasification ash water - Google Patents
Method for hardness removal of coal gasification ash water Download PDFInfo
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- CN114409141A CN114409141A CN202210134091.2A CN202210134091A CN114409141A CN 114409141 A CN114409141 A CN 114409141A CN 202210134091 A CN202210134091 A CN 202210134091A CN 114409141 A CN114409141 A CN 114409141A
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- water
- coal gasification
- silicate
- phosphate
- hardness
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- 238000000034 method Methods 0.000 title claims abstract description 76
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 75
- 239000003245 coal Substances 0.000 title claims abstract description 68
- 238000002309 gasification Methods 0.000 title claims abstract description 66
- 239000010797 grey water Substances 0.000 claims abstract description 73
- 238000011282 treatment Methods 0.000 claims abstract description 51
- 229910019142 PO4 Inorganic materials 0.000 claims abstract description 35
- 239000010452 phosphate Substances 0.000 claims abstract description 32
- 239000002244 precipitate Substances 0.000 claims abstract description 28
- 230000015271 coagulation Effects 0.000 claims abstract description 25
- 238000005345 coagulation Methods 0.000 claims abstract description 25
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims abstract description 23
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims abstract description 17
- 238000003756 stirring Methods 0.000 claims abstract description 12
- 239000006228 supernatant Substances 0.000 claims abstract description 12
- 238000001914 filtration Methods 0.000 claims abstract description 11
- 230000001376 precipitating effect Effects 0.000 claims abstract description 11
- 238000006243 chemical reaction Methods 0.000 claims abstract description 3
- 238000004064 recycling Methods 0.000 claims abstract description 3
- 238000005189 flocculation Methods 0.000 claims description 27
- 230000016615 flocculation Effects 0.000 claims description 26
- 239000000126 substance Substances 0.000 claims description 25
- 238000001556 precipitation Methods 0.000 claims description 22
- 239000000956 alloy Substances 0.000 claims description 10
- 239000001506 calcium phosphate Substances 0.000 claims description 10
- 235000011010 calcium phosphates Nutrition 0.000 claims description 10
- 229910001425 magnesium ion Inorganic materials 0.000 claims description 10
- GVALZJMUIHGIMD-UHFFFAOYSA-H magnesium phosphate Chemical compound [Mg+2].[Mg+2].[Mg+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O GVALZJMUIHGIMD-UHFFFAOYSA-H 0.000 claims description 10
- 239000004137 magnesium phosphate Substances 0.000 claims description 10
- 235000010994 magnesium phosphates Nutrition 0.000 claims description 10
- 229910000389 calcium phosphate Inorganic materials 0.000 claims description 9
- 229910000157 magnesium phosphate Inorganic materials 0.000 claims description 9
- 229960002261 magnesium phosphate Drugs 0.000 claims description 9
- 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 claims description 9
- 239000000378 calcium silicate Substances 0.000 claims description 8
- 229910052918 calcium silicate Inorganic materials 0.000 claims description 8
- 235000012241 calcium silicate Nutrition 0.000 claims description 8
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 claims description 8
- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 claims description 8
- 239000000391 magnesium silicate Substances 0.000 claims description 8
- 229910052919 magnesium silicate Inorganic materials 0.000 claims description 8
- 235000019792 magnesium silicate Nutrition 0.000 claims description 8
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 claims description 6
- 239000010405 anode material Substances 0.000 claims description 6
- ZFXVRMSLJDYJCH-UHFFFAOYSA-N calcium magnesium Chemical compound [Mg].[Ca] ZFXVRMSLJDYJCH-UHFFFAOYSA-N 0.000 claims description 5
- 239000000701 coagulant Substances 0.000 claims description 5
- 229910000838 Al alloy Inorganic materials 0.000 claims description 3
- 229910000640 Fe alloy Inorganic materials 0.000 claims description 3
- 229910021578 Iron(III) chloride Inorganic materials 0.000 claims description 3
- 229910001297 Zn alloy Inorganic materials 0.000 claims description 3
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 3
- 125000002467 phosphate group Chemical group [H]OP(=O)(O[H])O[*] 0.000 claims description 3
- 230000001112 coagulating effect Effects 0.000 claims description 2
- 239000000463 material Substances 0.000 claims description 2
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 claims description 2
- 159000000000 sodium salts Chemical class 0.000 claims description 2
- 239000010703 silicon Substances 0.000 abstract description 17
- 229910052710 silicon Inorganic materials 0.000 abstract description 17
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 abstract description 11
- 239000011575 calcium Substances 0.000 abstract description 10
- 229910052791 calcium Inorganic materials 0.000 abstract description 8
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 abstract description 7
- 239000011777 magnesium Substances 0.000 abstract description 7
- 229910052749 magnesium Inorganic materials 0.000 abstract description 7
- -1 silicon ions Chemical class 0.000 abstract description 3
- 239000000203 mixture Substances 0.000 abstract description 2
- 235000021317 phosphate Nutrition 0.000 description 21
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 14
- 239000003814 drug Substances 0.000 description 12
- 230000008569 process Effects 0.000 description 12
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 10
- 238000001514 detection method Methods 0.000 description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 6
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 6
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 6
- 239000010866 blackwater Substances 0.000 description 6
- 239000003513 alkali Substances 0.000 description 5
- 238000004062 sedimentation Methods 0.000 description 5
- 229910000029 sodium carbonate Inorganic materials 0.000 description 5
- 235000017550 sodium carbonate Nutrition 0.000 description 5
- 229910020489 SiO3 Inorganic materials 0.000 description 4
- 230000003139 buffering effect Effects 0.000 description 4
- 229910000019 calcium carbonate Inorganic materials 0.000 description 4
- 229910001424 calcium ion Inorganic materials 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000005868 electrolysis reaction Methods 0.000 description 4
- 239000002253 acid Substances 0.000 description 3
- 239000000872 buffer Substances 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 229910052681 coesite Inorganic materials 0.000 description 3
- 229910052906 cristobalite Inorganic materials 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- 239000003381 stabilizer Substances 0.000 description 3
- 229910052682 stishovite Inorganic materials 0.000 description 3
- 229910052905 tridymite Inorganic materials 0.000 description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 2
- 241000196324 Embryophyta Species 0.000 description 2
- 241000565357 Fraxinus nigra Species 0.000 description 2
- 241001460678 Napo <wasp> Species 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000005518 electrochemistry Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 2
- 239000000347 magnesium hydroxide Substances 0.000 description 2
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 2
- 150000004760 silicates Chemical class 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 229910003243 Na2SiO3·9H2O Inorganic materials 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 239000006172 buffering agent Substances 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 239000013043 chemical agent Substances 0.000 description 1
- 239000003034 coal gas Substances 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 238000011284 combination treatment Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000005685 electric field effect Effects 0.000 description 1
- 239000008394 flocculating agent Substances 0.000 description 1
- 230000003311 flocculating effect Effects 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000013505 freshwater Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 159000000003 magnesium salts Chemical class 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000012716 precipitator Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 239000002455 scale inhibitor Substances 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 238000010408 sweeping Methods 0.000 description 1
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 1
- 229910000406 trisodium phosphate Inorganic materials 0.000 description 1
Classifications
-
- 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
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/02—Softening water by precipitation of the hardness
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/02—Softening water by precipitation of the hardness
- C02F5/04—Softening water by precipitation of the hardness using phosphates
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
- C02F1/463—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrocoagulation
-
- 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
-
- 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
- C02F2001/007—Processes including a sedimentation step
-
- 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
-
- 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
- C02F2101/105—Phosphorus compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
Landscapes
- 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 Of Suspended Particles By Flocculating Agents (AREA)
Abstract
The invention discloses a method for hardness removal of coal gasification grey water, which comprises the steps of adding phosphate and/or silicate into coal gasification black grey water to be treated, stirring to enable the mixture to react fully to generate precipitate, and performing pre-settling treatment for 5-10 min after the reaction is finished; then carrying out coagulation treatment on the obtained supernatant to remove residual phosphate radicals and silicate radicals in the water body; and precipitating and filtering the coagulated water body to obtain softened water, so as to meet the recycling requirement. The method can effectively remove calcium, magnesium and silicon ions in the gasified ash water, and simultaneously remove suspended matters and turbidity, and has the advantages of high treatment efficiency, low cost and strong practicability.
Description
Technical Field
The invention belongs to the technical field of sewage treatment, and particularly relates to a method for hardness removal of coal gasification grey water.
Background
China has abundant coal resources, and coal gasification is an environment-friendly, clean and efficient coal comprehensive utilization technology. In recent years, coal gasification technology has been widely applied, but the treatment process of a large amount of coal gasification grey water generated in the process system is not perfect, the coal gasification grey water contains high-concentration calcium, magnesium and plasma, the problems of scaling blockage, corrosion and the like in equipment and pipelines are caused, even frequent parking is caused, and great economic loss is caused. It is therefore often necessary to ensure that the hardness of the system is maintained at a relatively low level by increasing the amount of ash discharged and replenishing large amounts of fresh water, which results in a significant waste of water resources. Therefore, the advanced treatment of the coal gas grey water and the improvement of the cyclic utilization rate of the coal gasification grey water become a key technology of the coal gasification technology for saving energy, reducing consumption, prolonging the system operation period and ensuring the stable operation of the system.
At present, the coal gasification grey water treatment method mainly comprises a medicament method, an ion exchange method, a membrane method, an electric flocculation method and the like. Among them, the chemical method is the most common and easier to implement than other treatment methods, and there are mainly two chemical methods. One is a method of adding a water quality stabilizer, such as adding a scale inhibitor, a dispersing agent and the like; the practical result shows that the characteristics of high temperature and high volatility of the coal gasification grey water system put higher requirements on the performance and the dosage of the medicament, and the water quality stabilizer method cannot fundamentally solve the risks of scaling and pollution blockage of the system and has the problem of huge water resource waste. In addition to the method of adding the water quality stabilizer, another method is to add a water quality softener, such as a lime softening method, a sodium carbonate + alkali method or a carbon dioxide + alkali method, and the like. Nevertheless, the coal gasification black ash water is often rich in buffering substances such as ammonia nitrogen and the like, so that the buffering performance of the ash water is particularly strong, and in the actual softening process, the efficiency of the medicament is very low due to the strong buffering performance of the ash water, the dosage of the medicament is tens of times of the theoretical softening demand, the medicament consumption is large, and the treatment effect is poor. In addition, in the water softener method, the process flow is long due to the slow sedimentation speed, and the equipment occupies a large area. At present, the electric flocculation technology is reported to be used for grey water, and because the alkalinity of bicarbonate radical in the grey water is low, calcium and magnesium ions in the grey water are difficult to remove by a single electric flocculation method, a medicament and the electric flocculation need to be combined. The currently reported methods of combining agents with electrochemical treatment techniques (electroflocculation techniques) are the combination of flocculants with electrochemistry, and the combination of sodium hydroxide with sodium carbonate or carbon dioxide with electrochemistry. The methods still have the problems of large dosage of chemicals and low treatment efficiency, so that the development of a hardness removal treatment process of the coal gasification grey water with low dosage of chemicals and high efficiency is necessary.
CN 201710160557.5 discloses a method for electrochemically removing hardness and turbidity of coal gasification grey water or black water; CN 106630307 a discloses a system and method for treating coal gasification grey water. In both patents, coal gasification grey water or black water is treated by a method of combining chemical agents (sodium hydroxide, sodium carbonate or carbon dioxide) and electric flocculation, the coal gasification black water is subjected to electric flocculation treatment to generate flocculation nuclei and form a flocculation nucleus net, and electrochemical synergistic softening is utilized. Although the method can reduce the hardness of the coal gasification grey water or black water and reduce the risk of scaling and fouling of the system, the grey water system has strong buffering property, the amount of alkali to be added in an alkalinity adjusting area is large, and the acid amount consumed by adjusting the pH value of the treated water is large, so that the cost is high. And because the water quality fluctuation of the grey and black water system is large, the requirement on the addition amount of carbonate is high, and if excessive addition amount exists or the carbonate which is not fully reacted is recycled to the grey and black water system after passing through a treatment device, the scaling risk of the system is increased.
CN 112811740A discloses a method for removing fluorine and hardness from industrial wastewater. In the method, the calcium-magnesium precipitator added for hardness removal is phosphoric acid, and the hardness in water is reduced by generating calcium phosphate and magnesium phosphate precipitates through phosphate radicals and calcium-magnesium ions in wastewater. Although this method can reduce the hardness of the wastewater, the presence of excessive phosphate can lead to a high phosphorus content in the treated water.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a method for removing hardness of coal gasification grey water, which can more effectively remove calcium, magnesium and silicon ions in the coal gasification grey water and remove suspended matters and turbidity simultaneously, and has the advantages of high treatment efficiency, low cost and strong practicability.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a method for hardness removal of coal gasification grey water, which comprises the following steps:
(1) adding a hardness remover into the coal gasification black ash water to be treated, stirring to enable the mixture to react fully to generate precipitate, and performing pre-sedimentation treatment for 5-10 min after the reaction is finished; the hardness remover is phosphate and/or silicate;
(2) coagulating the supernatant obtained in the step (1) to remove residual phosphate radicals and silicate radicals in the water body;
(3) and precipitating and filtering the coagulated water body to obtain softened water, so as to meet the recycling requirement.
In the method for removing hardness of the coal gasification grey water, the hardness of the coal gasification black grey water to be treated in the step (1) is 300-2000 mg/L and the alkalinity of bicarbonate is 0-100 mg/L, and the coal gasification grey water has the characteristics of high hardness, large fluctuation, low alkalinity of bicarbonate and strong acid-base buffer property. The traditional carbonate hardness removal process can consume a large amount of alkali and carbonate to effectively remove hardness in water body, and water after hardness removal needs to be supplemented with a large amount of acid to neutralize, so that the consumption of agents is large, the treatment efficiency is low, and the cost is high.
In the method for removing hardness of coal gasification grey water, the hardness remover phosphate and silicate in the step (1) are preferably one of sodium salt and potassium salt.
In the method for removing hardness of coal gasification grey water, the hardness remover in the step (1) is added in an amount of 80-150% of the mass of phosphate radicals or silicate radicals required for removing hardness according to the requirement so that phosphate, silicate and calcium magnesium ions are combined to generate calcium phosphate, magnesium phosphate or calcium silicate and magnesium silicate precipitates, and the more preferable amount is 90-105%. Adding phosphate and silicate to react with calcium salt and magnesium salt in the ash water to generate calcium phosphate and magnesium phosphate or calcium silicate and magnesium silicate precipitate to remove calcium ions and magnesium ions in the ash water; adding phosphate and silicate to raise the pH value of grey water, and removing calcium, magnesium and silicon ions from the grey water by using part of calcium and magnesium ions and the original silicon in the grey water to form calcium silicate precipitate and magnesium silicate precipitate; the reaction speed is accelerated by stirring, so that the precipitation is sufficient, the contents of phosphate radicals and silicate radicals in the supernatant obtained after the pre-precipitation treatment can be effectively reduced, and the subsequent treatment difficulty and cost are reduced.
Further, the pre-sedimentation treatment in the step (1) is natural sedimentation.
Further, the coagulation treatment in the step (2) is an electric flocculation treatment, a chemical coagulation treatment, or a combination treatment of electric flocculation and chemical coagulation. The coagulation treatment is electric flocculation treatment, wherein the anode material of the device used for the electric flocculation treatment preferably selects iron alloy material, aluminum alloy material, zinc alloy material or the combination of two or three materials. The coagulation treatment is chemical coagulation, wherein a coagulant used for the chemical coagulation is preferably polymeric ferric chloride, polymeric aluminum chloride or a combination of the polymeric ferric chloride and the polymeric aluminum chloride.
Electric flocculation treatment is adopted: under the action of an electric field, high-activity adsorption groups are generated to adsorb phosphate and colloid particles in water,suspended matter, non-soluble organic matter, heavy metal ion, SiO2And the impurities form a larger flocculating body structure to be separated out from the water, and an electric field effect, a flocculation effect, an adsorption bridge action, a net laying and sweeping effect and the like exist all the time in the electric flocculation process. Electrolytic generation of OH-Generating magnesium hydroxide precipitate with magnesium ions to further remove magnesium ions, and electrolyzing generated OH-Can improve the pH value of water and has synergistic effect on the further sedimentation of insoluble substances. Chemical coagulation: the method adopts polyferric chloride, polyaluminium chloride or the combination of the polyferric chloride and the polyaluminium chloride, and after a coagulant is added, the formation and growth of crystal nuclei of calcium phosphate, magnesium phosphate or calcium silicate and magnesium silicate are accelerated, and the effect of efficiently reducing impurities such as turbidity, suspended matters, organic matters and the like of the grey water is realized through the rapid growth and collision of the crystal nuclei and the adsorption effect of the coagulant.
The applicant has conducted a great deal of experimental research on the calcium and magnesium removing medicament, and found that it is impossible to replace the phosphate and silicate with other medicaments, for example, carbonate is used instead of phosphate and silicate, and because of the strong buffering property of the grey water, sodium hydroxide is required while carbonate is added, and the addition amount is large, compared with the medicament used in the present invention, although all the precipitates are generated, the formation of crystal nuclei of calcium phosphate, magnesium phosphate, calcium silicate and magnesium silicate is faster, the precipitation speed of the calcium phosphate, magnesium phosphate, calcium silicate and magnesium silicate is much higher than that of calcium carbonate and magnesium hydroxide, the treatment efficiency of the grey water is obviously improved, and the practicability is stronger. The carbonate and the silicate can solve the problem of strong buffer property of the grey water, greatly reduce the dosage of the medicament and be more economical.
Compared with the prior art, the coal gasification ash water hardness and silicon removal method has the advantages that:
1) the coal gasification ash water hardness removal and silicon removal method breaks through the conventional thinking of removing hardness by generating calcium carbonate precipitate, utilizes the method for removing hardness by generating calcium phosphate and magnesium phosphate with lower solubility product, has high hardness removal efficiency and simple and convenient operation; and does not need to add alkali or acid, so that the operation is safe and simple, and the precipitation speed is high;
2) the method optimizes the selection and addition of the medicament and the process after adding the medicament, thereby not only removing scale forming ions such as calcium, magnesium, silicon and the like in the grey water, but also reducing the turbidity of the grey water, removing suspended matters in the grey water and removing residual phosphate radicals; the removal rate of calcium, magnesium and silicon can reach more than 85 percent.
3) The coal gasification ash water hardness removal method has the advantages of simple process, convenient operation and strong practicability;
4) according to the method, phosphates and/or silicates are added to generate insoluble precipitates of calcium and magnesium phosphates, silicates and the like, calcium and magnesium ions in water are further removed through coagulation treatment, and silicon, residual phosphate radicals and other suspended matters can be removed.
Detailed Description
The present invention is described in detail below with reference to specific examples, but is not limited to the examples.
Example 1
The coal gasification grey water conditions for a certain chemical plant are shown in table 1:
TABLE 1
Note: hardness and basicity as CaCO3In terms of Si in SiO2And (6) counting.
The method for removing hardness and silicon of the coal gasification grey water comprises the following steps:
(1) na was added to the coal gasification ash water of Table 1 at 2.9g/L3PO4·12H2O, stirring to fully react to generate precipitates, generating a large amount of precipitates, and carrying out pre-precipitation treatment for 8min, wherein the precipitation speed is high;
(2) overflowing the supernatant to an electric flocculation device for electric flocculation treatment to remove residual phosphate radicals in the water body, wherein the anode material is an iron alloy material, and the current density is 10mA/cm2The electrolysis time is 5 min;
(3) and (3) precipitating and filtering the treated water in the step (2) to obtain the treated grey water.
Wherein, the water treated in the detection step (3) is shown in the table 2:
TABLE 2
Example 2
The method for removing hardness and silicon of the coal gasification grey water is adopted to treat the coal gasification grey water:
(1) na was added to the coal gasification ash water of Table 1 at 2.9g/L3PO4·12H2O, stirring to fully react to generate precipitates, generating a large amount of precipitates, and carrying out pre-precipitation treatment for 8min, wherein the precipitation speed is high;
(2) overflowing the supernatant to a chemical coagulation device for chemical coagulation to remove residual phosphate radicals in a water body, and adding polyferric chloride according to the effective content of 30 mg/L;
(3) and (3) precipitating and filtering the treated water in the step (2) to obtain the treated grey water.
Wherein, the water treated in the detection step (3) is shown in the table 3:
TABLE 3
Example 3
The method for removing hardness and silicon from the coal gasification grey water to treat the coal gasification grey water comprises the following specific steps:
(1) na was added to the gasified soda ash water of Table 1 at a ratio of 3.3g/L2SiO3·9H2O, stirring to fully react to generate precipitates, generating a large amount of precipitates, and carrying out pre-precipitation treatment for 8min, wherein the precipitation speed is high;
(2) overflowing the supernatant to an electric flocculation device for electric flocculation to remove the residual silicate in the water body, wherein the anode material is an aluminum alloy material with the current density of 10mA/cm2The electrolysis time is 5 min;
(3) and (3) precipitating and filtering the treated water in the step (2) to obtain the treated grey water.
Wherein, the water treated in the detection step (3) is shown in the table 4:
TABLE 4
Example 4
The method for treating the coal gasification grey water by removing hardness and silicon of the coal gasification grey water comprises the following specific steps
(1) Na was added to the gasified soda ash water of Table 1 at a ratio of 3.3g/L2SiO3·9H2O, stirring to fully react to generate precipitates, generating a large amount of precipitates, and carrying out pre-precipitation treatment for 8min, wherein the precipitation speed is high;
(2) overflowing the supernatant liquid to a chemical coagulation device for chemical coagulation, removing residual silicate in a water body, and adding polyaluminium chloride according to the effective content of 30 mg/L;
(3) and (3) precipitating and filtering the treated water in the step (2) to obtain the treated grey water.
Wherein, the water treated in the detection step (3) is shown in the table 5:
TABLE 5
Example 5
The coal gasification grey water conditions for a certain chemical plant are shown in table 6:
TABLE 6
Note: hardness and basicity as CaCO3In terms of Si in SiO2And (6) counting.
The invention provides a method for removing hardness and silicon of coal gasification grey water, which comprises the following steps:
(1) adding NaPO into the coal gasification ash water of Table 6 according to 4.4g/L4·12H2O, stirring to fully react to generate precipitates, generating a large amount of precipitates, and carrying out pre-precipitation treatment for 8min, wherein the precipitation speed is high;
(2) overflowing the supernatant to an electric flocculation device for electric flocculation to remove residues in the water bodyThe remained phosphate radical and the anode material are made of zinc alloy material with the current density of 12mA/cm2The electrolysis time is 5 min;
(3) and (3) precipitating and filtering the treated water in the step (2) to obtain the treated grey water.
Wherein, the water treated in the detection step (3) is shown in the table 7:
TABLE 7
Example 6
The method for removing hardness and silicon from the coal gasification grey water to treat the coal gasification grey water comprises the following specific steps:
(1) adding NaPO into the coal gasification ash water of Table 6 according to 4.4g/L4·12H2O, stirring to fully react to generate precipitates, generating a large amount of precipitates, and carrying out pre-precipitation treatment for 8min, wherein the precipitation speed is high;
(2) overflowing the supernatant to a chemical coagulation device for chemical coagulation to remove residual phosphate radicals in a water body, and adding polyferric chloride/aluminum according to 40 mg/L;
(3) and (3) precipitating and filtering the treated water in the step (2) to obtain the treated grey water.
Wherein, the water treated in the detection step (3) is shown in the table 8:
TABLE 8
Example 7
The invention provides a method for removing hardness and silicon of coal gasification grey water, which comprises the following steps:
(1) na was added to the coal gasification ash water of Table 6 at 4.9g/L2SiO3·9H2O, stirring to fully react to generate precipitates, generating a large amount of precipitates, and carrying out pre-precipitation treatment for 8min, wherein the precipitation speed is high;
(2) overflowing the supernatant liquid in the step (1) to an electric flocculation device for electric flocculation to remove the residual silicate in the water body, wherein the anode material is ironAluminum alloy material with current density of 12mA/cm2The electrolysis time is 5 min;
(3) and (3) precipitating and filtering the treated water in the step (2) to obtain the treated grey water.
Wherein, the water treated in the detection step (3) is shown in the table 9:
TABLE 9
Example 8
The method for removing hardness and silicon from the coal gasification grey water to treat the coal gasification grey water comprises the following specific steps:
(1) na was added to the coal gasification ash water of Table 6 at 4.9g/L2SiO3·9H2O, stirring to fully react to generate precipitates, generating a large amount of precipitates, and carrying out pre-precipitation treatment for 8min, wherein the precipitation speed is high;
(2) overflowing the supernatant liquid in the step (1) to a chemical coagulation device for chemical coagulation, removing residual silicate in a water body, and adding polyferric chloride according to 40 mg/L;
(3) and (3) precipitating and filtering the treated water in the step (2) to obtain the treated grey water.
Wherein, the water treated in the detection step (3) is shown in a table 10:
watch 10
Comparative example 1
The difference from example 1 is only in the hardness remover in step (1), and in comparative example 1, Na is used2CO3Substitute for Na3PO4·12H2O, the addition amount is 1.3 g/L; the water after the detection treatment is shown in Table 11:
comparative example 2
The difference from example 5 is only in that the hardness remover in step (1) is different, and Na is added in comparative example 22CO3Substitute for Na2SiO3·9H2O, the addition amount is 1.8 g/L. The water after the detection treatment is shown in Table 11:
TABLE 11
As shown in tables 1-11, under the condition of the same molar ratio addition as the hardness, the hardness removal efficiency of the process adopting phosphate or silicate as the hardness removal agent is higher than that of the process adopting carbonate, which shows that the method for removing hardness from coal gasification grey water provided by the invention has better hardness removal effect on coal gasification grey water, can well avoid the problem of strong buffer property of water to be treated, and solves the problems of low efficiency, long process flow, large equipment occupation area and the like of the existing process for removing hardness from grey water.
The above-mentioned embodiments are merely provided to fully illustrate the present invention, but the scope of the present invention is not limited thereto, and those skilled in the art should make equivalents and modifications based on the present invention within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (9)
1. A method of coal gasification grey water de-hardening, characterized in that the method comprises the steps of:
1) adding a hardness remover into the coal gasification ash water to be treated, stirring to enable the coal gasification ash water to react fully to generate precipitate, and performing pre-settling treatment for 5-10 min after the reaction is finished; the hardness remover is phosphate and/or silicate;
2) coagulating the supernatant obtained in the step 1) to remove residual phosphate radicals and silicate radicals in the water body;
3) precipitating and filtering the coagulated water body to obtain softened water which meets the recycling requirement;
wherein the addition amount of the phosphate and the silicate is determined according to the removal hardness amount.
2. The coal gasification grey water hardness removal method according to claim 1, wherein the phosphate and silicate in step 1) are one of sodium salt and potassium salt.
3. The method for hardness removal of coal gasification grey water according to claim 1, wherein the hardness remover is added in an amount of 80-150% of the amount of substance of phosphate or silicate required for removing hardness according to the required amount to combine phosphate, silicate and calcium magnesium ions to form calcium phosphate, magnesium phosphate or calcium silicate, magnesium silicate precipitation.
4. The method for hardness removal of coal gasification grey water according to claim 3, wherein the amount of the phosphate or silicate is 90-105% of the amount of the phosphate or silicate to be combined with calcium magnesium ions to form calcium phosphate, magnesium phosphate or calcium silicate, or the amount of phosphate or silicate needed for precipitation of magnesium silicate, according to the amount of hardness removal required.
5. The coal gasification grey water hardness removal method according to claim 1, wherein the pre-settling treatment in step 1) is natural settling.
6. The coal gasification grey water hardness removal method according to claim 1, wherein the coagulation treatment in step 2) is an electric flocculation treatment, a chemical coagulation treatment, or a combination of electric flocculation and chemical coagulation treatment.
7. The coal gasification grey water hardness removal method according to claim 6, wherein the coagulation treatment is an electric flocculation treatment, and the anode material of the device used in the electric flocculation treatment is selected from iron alloy material, aluminum alloy material, zinc alloy material or a combination of two or three of the materials.
8. The method for hardness removal of coal gasification grey water according to claim 6, wherein the coagulation treatment is chemical coagulation, wherein the coagulant used in the chemical coagulation is poly-ferric chloride, poly-aluminum chloride or a combination of the two.
9. The coal gasification grey water hardness removal method according to claim 8, wherein the molar amount of the coagulant added is 1.1-1.5 of the molar amount of the residual phosphate or silicate in the step 2).
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