CN112830505B - Method for purifying salt mother liquor slurry by flue gas method - Google Patents
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- 239000002002 slurry Substances 0.000 title claims abstract description 74
- 150000003839 salts Chemical class 0.000 title claims abstract description 72
- 239000003546 flue gas Substances 0.000 title claims abstract description 67
- 239000012452 mother liquor Substances 0.000 title claims abstract description 67
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 66
- 238000000034 method Methods 0.000 title claims abstract description 52
- 238000006243 chemical reaction Methods 0.000 claims abstract description 43
- 238000003763 carbonization Methods 0.000 claims abstract description 26
- 239000007788 liquid Substances 0.000 claims abstract description 25
- 229910052736 halogen Inorganic materials 0.000 claims abstract description 22
- 150000002367 halogens Chemical class 0.000 claims abstract description 22
- 239000000706 filtrate Substances 0.000 claims abstract description 19
- 239000002245 particle Substances 0.000 claims abstract description 18
- 239000007789 gas Substances 0.000 claims abstract description 17
- 238000000746 purification Methods 0.000 claims abstract description 15
- 239000012528 membrane Substances 0.000 claims abstract description 13
- 239000007787 solid Substances 0.000 claims abstract description 12
- 229910002651 NO3 Inorganic materials 0.000 claims abstract description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000012535 impurity Substances 0.000 claims abstract description 10
- 238000000108 ultra-filtration Methods 0.000 claims abstract description 10
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims abstract description 9
- 239000000428 dust Substances 0.000 claims abstract description 9
- 239000000779 smoke Substances 0.000 claims abstract description 9
- 238000001704 evaporation Methods 0.000 claims abstract description 6
- 230000008020 evaporation Effects 0.000 claims abstract description 6
- 238000000926 separation method Methods 0.000 claims abstract description 5
- 238000001728 nano-filtration Methods 0.000 claims abstract description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 28
- 239000000126 substance Substances 0.000 claims description 15
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 238000006477 desulfuration reaction Methods 0.000 claims description 5
- 230000023556 desulfurization Effects 0.000 claims description 5
- 238000001914 filtration Methods 0.000 claims description 5
- 238000005406 washing Methods 0.000 claims description 4
- 238000004364 calculation method Methods 0.000 claims description 3
- 238000005070 sampling Methods 0.000 claims description 3
- 239000000919 ceramic Substances 0.000 claims 1
- 239000012510 hollow fiber Substances 0.000 claims 1
- 239000000725 suspension Substances 0.000 claims 1
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 abstract description 22
- 239000000203 mixture Substances 0.000 abstract description 4
- 239000012267 brine Substances 0.000 description 26
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 26
- 230000008569 process Effects 0.000 description 19
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 12
- 239000011777 magnesium Substances 0.000 description 12
- 239000002699 waste material Substances 0.000 description 12
- 239000011575 calcium Substances 0.000 description 9
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 8
- 235000010333 potassium nitrate Nutrition 0.000 description 8
- 238000002360 preparation method Methods 0.000 description 7
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 6
- 235000011941 Tilia x europaea Nutrition 0.000 description 6
- 239000004571 lime Substances 0.000 description 6
- 239000002994 raw material Substances 0.000 description 6
- 235000011121 sodium hydroxide Nutrition 0.000 description 6
- 241001131796 Botaurus stellaris Species 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 235000017550 sodium carbonate Nutrition 0.000 description 5
- 229910000029 sodium carbonate Inorganic materials 0.000 description 5
- 230000007613 environmental effect Effects 0.000 description 4
- 229910052602 gypsum Inorganic materials 0.000 description 4
- 239000010440 gypsum Substances 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 3
- 239000012752 auxiliary agent Substances 0.000 description 3
- 230000006835 compression Effects 0.000 description 3
- 238000007906 compression Methods 0.000 description 3
- 230000003009 desulfurizing effect Effects 0.000 description 3
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 3
- 239000000347 magnesium hydroxide Substances 0.000 description 3
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- 239000002910 solid waste Substances 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- 229910019440 Mg(OH) Inorganic materials 0.000 description 2
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 239000003814 drug Substances 0.000 description 2
- 238000004134 energy conservation Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000004062 sedimentation Methods 0.000 description 2
- 208000005156 Dehydration Diseases 0.000 description 1
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- ZFXVRMSLJDYJCH-UHFFFAOYSA-N calcium magnesium Chemical compound [Mg].[Ca] ZFXVRMSLJDYJCH-UHFFFAOYSA-N 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000006298 dechlorination reaction Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000008394 flocculating agent Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000010808 liquid waste Substances 0.000 description 1
- 229910001425 magnesium ion Inorganic materials 0.000 description 1
- 239000002075 main ingredient Substances 0.000 description 1
- 238000005374 membrane filtration Methods 0.000 description 1
- 239000008267 milk Substances 0.000 description 1
- 235000013336 milk Nutrition 0.000 description 1
- 210000004080 milk Anatomy 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- HUAUNKAZQWMVFY-UHFFFAOYSA-M sodium;oxocalcium;hydroxide Chemical compound [OH-].[Na+].[Ca]=O HUAUNKAZQWMVFY-UHFFFAOYSA-M 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D3/00—Halides of sodium, potassium or alkali metals in general
- C01D3/14—Purification
- C01D3/16—Purification by precipitation or adsorption
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/80—Semi-solid phase processes, i.e. by using slurries
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- General Chemical & Material Sciences (AREA)
- Biomedical Technology (AREA)
- Analytical Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Treating Waste Gases (AREA)
Abstract
The invention belongs to the technical field of salt making, and particularly relates to a method for purifying salt making mother liquor slurry by a flue gas method, wherein a flue gas pipeline reactor is adopted to convey the mother liquor slurry mixed with solid and liquid salt and nitrate to be mixed with unsaturated crude halogen, pressurized flue gas is introduced, a carbonization reaction is simultaneously carried out in the pipeline in a circulating manner, the pH value is 8.5-9.0, the mixture is stopped, gas-liquid separation is carried out, then the mixture is filtered by an ultrafiltration membrane, and filtrate is recycled to a vacuum salt making triple-effect evaporation tank to prepare liquid salt by connecting nitrate and salt or a nanofiltration membrane; the filtered and solidified salty mud is applied to purifying flue gas through pretreatment, and the purified flue gas is applied to mother liquor slurry purification after being secondarily purified by a water circulation compressor. The method utilizes the pressurized flue gas pipeline to convey the mother liquor slurry and simultaneously carry out carbonization reaction, simplifies the purification process and obviously improves the carbonization reaction rate; adopting unsaturated original halogen to utilize two alkalis in the mother liquor slurry and dissolve solid salt and nitre in the mother liquor slurry; the salty mud is applied to purifying flue gas through pretreatment, and impurity gas and smoke dust particles in the flue gas are removed.
Description
Technical Field
The invention belongs to the technical field of environmental protection and waste resource utilization, and particularly relates to a method for purifying and preparing salt mother liquor slurry by a flue gas method and application thereof.
Background
With the sustainable progress of economic development and industrialization in China, as the environmental protection pressure is continuously increased, the national requirements on the emission of solid waste, liquid waste and gas waste, the effective utilization of resources and the energy conservation and consumption reduction are higher and higher, so that the problems of solid waste, resource reutilization, energy conservation and consumption reduction are to be solved in the salt industry. Flue gas has N as the main component 2 、O 2 、CO 2 、H 2 O, its direct discharge into the atmosphere can have environmental impact. A large amount of solid-liquid mixed mother liquor slurry can be generated in the production process of salt industry, or the solid-liquid mixed mother liquor slurry which needs to be discharged in large amount due to difficult saltpeter precipitation in the vacuum saltpeter preparation process, and the main components of the solid-liquid mixed mother liquor slurry of the saltpeter and the saltpeter are NaCl: 305-330 g/L, na 2 SO 4 ：60～104g/L、Na 2 CO 3 : 16-20 g/L, naOH: 6-8 g/L of CO in the mother liquor slurry 3 2- 、OH - Is too high and contains supersaturated NaCl and Na 2 SO 4 The method is to search the most effective method for treating and utilizing the mother liquor, and overcome the problem that the high sulfate radical content of the high-nitrate brine is unfavorable to the subsequent salt making process and the salt quality, and is a problem to be solved urgently in the salt industry.
Cn103979579b. A method for preparing low calcium magnesium salt by using a downhole denitration process. And (3) carrying out denitration and magnesium removal on the mother liquor recovered salt dissolving cavity to obtain underground purified brine, and adding hot alkali liquor to remove calcium to obtain refined brine for salt preparation. The method produces a large amount of calcium sulfate and magnesium hydroxide precipitates which are difficult to settle in the original bittern, and the granular powder of calcium sulfate and the granular powder of magnesium hydroxide have high viscosity, small granular particles of magnesium hydroxide and light weight, so that the inner wall of a pipeline is easy to scale and even block in the pipeline conveying process of the original bittern. And the content of the nitrate in the mother liquor is higher, the content of the nitrate in the original brine is increased, the difficulty in separating the salt and the nitrate in the salt preparation process is increased, and the quality of the salt of a terminal product is influenced.
Cn106986356b. A lime-flue gas brine purification method: firstly, pre-feeding lime, then adding soda ash into original halogen, and finally adding the rest lime; and if the salt slurry is qualified, performing steps, and if the salt slurry does not reach the standard, further purifying by using caustic soda and soda ash, wherein a flocculating agent is required to be added for sedimentation in primary and secondary salt slurry sedimentation, and transferring the settled solution to a refined brine barrel of a salt making workshop. The flue gas brine is adopted for purification, the process is complex, the production time is long, and soda ash, lime and an auxiliary flocculant are added in the reaction process, so that the raw material cost is increased.
CN201310391191.4 sulfur dioxide absorption with lime flue gas process secondary salt mud as material is carried out by adding water into washed salt mud (particle size 20-80 um) to prepare slurry with solid content of 5-30%, and adding 0.05-1% organic acid to improve desulfurization efficiency. The salt slurry washing water consumption is too large, the salt slurry particle size is more than 60um, and slightly soluble calcium sulfate is easily generated on the surface of the salt slurry particles during wet desulphurization, SO that the interior of the salt slurry particles and SO are inhibited 2 Contact, reduce the dissolution rate of the salt mud, increase the scaling tendency, thereby reducing the utilization rate of the salt mud and influencing the quality of the terminal gypsum。
The method adopts the pressurized flue gas pipeline to convey the mother liquor slurry to be mixed with the brine and simultaneously carry out carbonization reaction, simplifies the purification process, shortens the process production time, does not need to add additives and auxiliaries, and obviously improves the carbonization reaction rate; unsaturated raw halogen and mother liquor are used as raw materials, so that solid salt and nitrate in the mother liquor can be dissolved; the salty mud is applied to purifying flue gas through pretreatment, and impurity gases and smoke dust particles in the flue gas are removed. The yield and the economic added value of the vacuum salt and the saltpeter are increased, the phenomenon of resource waste is reduced, multiple targets of using waste to prepare waste, changing waste into valuable, saving materials, reducing emission, saving the consumption of the soda ash and the like are achieved, and the method has important economic and environmental protection practical values.
Disclosure of Invention
In order to increase the yield and the economic added value of the vacuum salt and the saltpeter and reduce the phenomenon of resource waste, the most effective method for treating and utilizing the mother liquor slurry is explored, and the problem is urgently needed to be solved in the salt industry. The method adopts the pressurized flue gas pipeline to convey the mother liquor slurry to be mixed with the brine and simultaneously carry out carbonization reaction without adding any additive and auxiliary agent, the brine refining process flow after technical transformation is more reasonable and practical, the running time of the process technology is reduced, and the carbonization reaction rate is obviously improved; and the product quality is improved and the production cost is reduced.
In order to realize the purpose, the technical scheme is as follows:
(1) Mother liquor slurry treatment
Firstly, desulfurizing and purifying flue gas by using salty mud, compressing the purified flue gas by using gas (the gas pressure is 0.2-0.5 MPa), carrying out secondary purification, introducing the flue gas into a pipeline reactor (the circulation is carried out by using the pressure of the gas), simultaneously conveying mixed halogen liquid of mother liquor slurry and unsaturated original halogen into a circulating pipeline, carrying out carbonization reaction in the pipeline, automatically controlling the carbonization reaction end point on line by using a pH meter, stopping ventilation (the process reaction is about 20-50 min) when the pH value is 8.5-9.0, finishing the carbonization reaction, separating residual gas by using gas-liquid separation equipment after the carbonization reaction is finished, and filtering the residual reaction mixed liquid by using an ultrafiltration membrane to respectively obtain filtrate and salty mud;
sampling detectionIndex of filtrate Ca 2+ ≤7mg/L，Mg 2+ Less than or equal to 3mg/L (before ultrafiltration membrane filtration).
The reactions taking place in the recycle line were:
introducing flue gas into mother liquor slurry for reaction: CO 2 2 +2OH - ＝CO 3 2- +H 2 O；
Reaction with calcium and magnesium in the original halogen: ca 2+ +CO 3 2- →CaCO 3 ↓
Mg 2+ +2OH - →Mg(OH) 2 ↓
Further, the main components of the mother liquor slurry are as follows: ca 2+ ：3.0～3.5mg/L、Mg 2+ ：1.0～1.5mg/L、NaOH：6～8g/L、Na 2 CO 3 ：16～20g/L、Na 2 SO 4 ：60～104g/L、NaCl：305～330g/L。
The main component of the unsaturated original halogen is Ca 2+ ：700～750mg/L、Mg 2+ ：10～18mg/L、NaOH：0.002～0.005g/L、Na 2 CO 3 ：0.02～0.06g/L、Na 2 SO 4 ：6～9g/L、NaCl：270～285g/L。
The dosage of the mother liquor slurry and the unsaturated original halogen is calculated by a formula, and CO in the mother liquor slurry 3 2- And OH - The ratio of the total amount of substances to the amount of unsaturated orthohalogen substance Ca 2+ And Mg 2+ The quantity n ratio of the total substances is a calculation formula: n = [ (nCO) 3 2- +nOH - /2)/(nCa 2+ +nMg 2+ )]N is more than or equal to 1.18 and less than or equal to 1.30; (n represents the amount of substance)
The invention selects and mixes unsaturated raw bittern and mother liquor slurry as bittern raw material, ca in the bittern 2+ 、Mg 2+ And two alkalis (NaOH, na) in mother liquor slurry 2 CO 3 ) And (3) reacting to remove calcium and magnesium ions in the original halogen and dissolve solid salt and nitre in the mother liquor slurry by using the two alkalis in the mother liquor slurry.
Further, the main components of the purified flue gas are as follows: SO 2 ≤35mg/Nm 3 ，NOx≤40mg/Nm 3 ，NH 3 ≤2mg/Nm 3 The smoke dust particles are less than or equal to 1.5mg/Nm 3 (ii) a Pressure of water circulationCompressing the main impurity components of the secondary purified flue gas by a compressor: SO (SO) 2 ≤15mg/Nm 3 ，NO x ≤10mg/Nm 3 ，NH 3 ≤0.01mg/Nm 3 Smoke dust is less than or equal to 0.1mg/Nm 3 。
(2) All indexes of the filtrate obtained in the step (1) meet the requirements of refined brine indexes. And then, recovering the filtrate into a vacuum salt-making triple-effect evaporation tank for saltpeter making or preparing liquid salt through a nanofiltration membrane.
Further, the main components of the filtrate obtained by separation are as follows: ca 2+ ：5.0～6.5mg/L、Mg 2+ ：1.5～2.0mg/L、NaOH：0.10～0.15g/L、Na 2 CO 3 ：0.3～0.5g/L、Na 2 SO 4 : 9-15 g/L, naCl: 275-295 g/L, and less than or equal to 0.5mg/L of suspended substance SS in the filtrate.
(3) And (2) washing and filtering the solid separated by the ultrafiltration membrane in the step (1), collecting salt mud (the particle size is 15-55 um), and using the salt mud as a desulfurizing agent for purifying flue gas to remove impurity gas in the flue gas.
Further, the chemical composition of the salty mud is
The reaction of the salty mud purification flue gas is as follows:
2SO 2 +2CaCO 3 +O 2 →2CaSO 4 +2CO 2
2SO 2 +2Mg(OH) 2 +O 2 →2MgSO 4 +2H 2 O
NO X +OH - →NO 2 - +NO 3 - +H 2 O
the final pH value of the wet desulphurization is 5.4-5.8.
And (2) carrying out gas compression on the flue gas after the brine sludge is purified, introducing the compressed flue gas into a circulating pipeline reactor, carrying out gas-liquid mixing on the compressed flue gas and a brine raw material consisting of mother liquor slurry and raw brine to carry out carbonization reaction, and carrying out the subsequent operation of the step (1) after the carbonization reaction.
Wherein the salt mud has large granularityThe utilization rate of the salt slurry, the desulfurization efficiency, the quality of the gypsum slurry and the like are influenced directly. When the particle size of the salty mud is too large, the slightly soluble calcium sulfate is easily generated on the surface of the salty mud particles during wet desulphurization, SO that the interior of the salty mud particles and SO are inhibited 2 The contact reduces the dissolution rate of the salt mud, increases the scaling tendency, thereby reducing the utilization rate of the salt mud and influencing the quality of the terminal gypsum. The particle size of the salty mud is too small, the difficulty in dechlorination and dehydration treatment of the salty mud is increased, the quality of the salty mud is influenced, the corrosion tendency is increased, and the system reliability and the desulfurization efficiency are reduced. In addition, mg (OH) in the salt mud 2 Easy to absorb SO 2 And trace amount of NO x MgSO of product solubles 4 Prone to CaSO 4 Separating and improving the quality of gypsum, wherein in practical application, the particle size of the salty mud is 15-55 um, and the pH value is 5.4-5.8, which is the end point of wet desulphurization, so that the effect of removing impurity gas in flue gas is optimal.
Compared with the prior art, the invention has the following beneficial effects:
(1) The invention adopts a pipeline with pressure to convey the salt-nitrate mixed mother liquor slurry, brine and flue gas to mix and simultaneously carry out carbonization reaction without adding a material agent and an auxiliary agent, and the preparation flow not only reduces the operation time of the process, but also obviously improves the carbonization reaction rate; the product yield is improved and the production cost is reduced;
(2) The method adopts unsaturated raw brine and mother liquor slurry to be mixed as brine, the unsaturated raw brine and the mother liquor slurry have a synergistic effect, after the unsaturated raw brine and the mother liquor slurry are mixed, two alkalis in the mother liquor slurry are utilized, solid salt and nitre in the mother liquor slurry are dissolved, and the method for purifying the solid waste liquid saves the medicament cost: from 3 yuan/m 3 Reduced to 0 yuan/m 3 (ii) a The salty mud is applied to purifying flue gas through pretreatment, and impurity gases and smoke dust particles in the flue gas are removed. The yield and the economic added value of the vacuum salt and the saltpeter are increased, the phenomenon of resource waste is reduced, multiple targets of using waste to prepare waste, changing waste into valuable, saving materials, reducing emission, saving the consumption of the calcined soda and the like are realized, and the method has important economic and environmental-friendly practical values.
Drawings
FIG. 1 is a process flow of mother liquor slurry treatment.
Detailed Description
Example 1
(1) Firstly, desulfurizing and purifying flue gas by using salty mud, secondarily purifying the purified flue gas by using a water circulation compressor, compressing the pressure of the flue gas to 0.5Mpa, introducing the flue gas into a pipeline reactor, simultaneously conveying mother liquor slurry and unsaturated crude halogen to the pipeline reactor for mixing (the volume ratio of the mother liquor slurry to the unsaturated crude halogen can be calculated according to the quantity of substances and the concentration of the quantities of the substances), circulating the mixed solid and liquid gases in a pipeline by using the self pressure of the compressed flue gas, simultaneously carrying out carbonization reaction, automatically controlling the carbonization reaction end point on line by using a pH meter, and sampling and detecting the index of the refined halogen Ca after the reaction when the pH is 8.5-9.0 2+ ≤7mg/L，Mg 2+ Less than or equal to 3mg/L, separating gas and liquid after reaction, and filtering with an ultrafiltration membrane to obtain filtrate (the filtrate components are shown in Table 1), wherein suspended matter SS in the filtrate after the ultrafiltration membrane is less than or equal to 0.5mg/L, and each index of the filtrate meets the requirement of refined brine index.
Wherein the mother liquor slurry and the raw halogen components are shown in Table 1, and the main components of the introduced flue gas are as follows: SO (SO) 2 ≤35mg/Nm 3 ，NOx≤40mg/Nm 3 ，NH 3 ≤2mg/Nm 3 The smoke dust particles are less than or equal to 1.5mg/Nm 3 . And the main impurity components of the flue gas after secondary purification by a water circulation compressor are as follows: SO (SO) 2 ≤15mg/Nm 3 ，NO x ≤10mg/Nm 3 ，NH 3 ≤0.01mg/Nm 3 Smoke dust is less than or equal to 0.1mg/Nm 3 . The salt mud generated by the reaction of the mother liquor slurry and the original halogen is subsequently used as a desulfurizer for purifying flue gas.
TABLE 1 mother liquor pulp, raw brine, filtrate principal ingredients
The dosage of the mother liquor slurry and the unsaturated original halogen is calculated according to the following formula, and CO in the mother liquor slurry 3 2- And OH - Quantitative ratio of total substance to unsaturated primary halogen substance Ca 2+ And Mg 2+ The quantity ratio of the total substances is a calculation formula: n = [ (nCO) 3 2- +nOH - /2)/(nCa 2+ +nMg 2+ )]，1.18≤n≤1.3(nAmount of substance)
(2) Recovering the filtrate to a vacuum salt-making triple-effect evaporation tank for combined saltpeter salt making or nanofiltration membrane preparation of liquid salt; increasing the yield of vacuum salt and nitrate or liquid salt, recovering filtrate into a vacuum salt-making triple-effect evaporation tank for combined nitrate salt making, wherein the salt yield of each ton of mother liquor slurry is as follows: 0.25-0.28 t, nitre yield: 0.06-0.07 t; per m 3 And (3) recovering and utilizing mother liquor slurry to prepare liquid salt: 0.5-0.7 m 3 。
Washing the solid separated by the ultrafiltration membrane with water until the Cl in the solid (dry basis) - The content is less than or equal to 0.5 percent, salt mud is obtained after filtration and collection, and the components of the salt mud are shown in the table 2:
TABLE 2 main ingredients of salty mud
Properties of salt mud
The salty mud is used for purifying flue gas and removing impurity gases in the flue gas.
2SO 2 +2CaCO 3 +O 2 →2CaSO 4 +2CO 2
2SO 2 +2Mg(OH) 2 +O 2 →2MgSO 4 +2H 2 O
NO X +OH - →NO 2 - +NO 3 - +H 2 O
And (3) performing wet desulphurization, wherein the pH value at the end point of the wet desulphurization is 5.4-5.8, performing gas compression on the purified flue gas (controlling the gas pressure after the compression), introducing the compressed flue gas into a pipeline reactor, performing gas-liquid mixing with a brine raw material consisting of mother liquor slurry and crude brine, performing carbonization reaction, and performing the operation of the step (1) after the carbonization reaction, thereby continuously performing a circulating reaction.
The carbonization reaction of the flue gas introduced into the mixture of the mother liquor slurry and the original halogen comprises the following steps:
CO 2 +2OH - ＝CO 3 2- +H 2 O；
Ca 2+ +CO 3 2- →CaCO 3 ↓
Mg 2+ +2OH - →Mg(OH) 2 ↓
the major components of the flue gas during the recycle are compared in table 3:
TABLE 3 comparison of flue gas main impurities purification
The traditional brine purification process generally comprises two processes, namely a lime soda flue gas process and a caustic soda flue gas process, wherein saturated raw brine is used as a raw material, a small amount of mother liquor is added, lime milk, soda ash and other auxiliary materials are needed to promote the reaction, the reaction time of the whole process is long, and the further improvement of the yield of salt preparation, nitrate preparation and liquid salt is not facilitated.
Whereas example 1 employs a water recycle compressor flue gas line to transport a mother liquor slurry mixed with unsaturated orthohalogen that is recycled in the pipeline reactor while undergoing a carbonation reaction, the comparative results are shown in table 4, as compared to a conventional purification treatment process:
TABLE 4 comparison of the mother liquor slurry treatment process with the conventional brine purification process
As can be seen from the comparison in Table 4, the mother liquor slurry treatment process not only removes two alkalis in the mother liquor slurry, but also dissolves solid salt and nitre in the mother liquor slurry, so that the reaction efficiency and the process reaction time can be remarkably improved: 20-50 min; the medicament cost is saved: from 3 to 6 yuan/m 3 Reduced to 0 yuan/m 3 (ii) a The filtrate is recycled to a vacuum salt-making triple-effect evaporation tank for combined saltpetering salt making, and the recycling generates benefits: 20-40 yuan/m 3 . Saves reaction tank device, the dosage of two alkalis and auxiliary agents, does not limit waste liquid amount, and can be produced at any time and treated at any timeThe purification process is optimized, and the carbonization reaction efficiency is improved.
Claims (6)
1. A method for purifying and preparing salt mother liquor slurry by a flue gas method is characterized in that flue gas after desulfurization and purification is secondarily purified and compressed by a water circulation compressor, the flue gas is introduced into a pipeline reactor after the flue gas is compressed to the pressure of 0.2-0.5 MPa, mixed halogen liquid of the mother liquor slurry and unsaturated original halogen is conveyed into the pipeline reactor at the same time, carbonization reaction occurs in the pipeline reactor, the end point of the carbonization reaction is controlled on line by a pH meter, residual gas is separated by gas-liquid separation equipment after the carbonization reaction is finished, then the residual reaction mixed liquid is filtered by an ultrafiltration membrane to respectively obtain filtrate and salt slurry, wherein the filtrate is recycled into a vacuum salt-making triple-effect evaporation tank to carry out salt and nitrate co-production or is used for preparing liquid salt by a nanofiltration membrane, the salt slurry is pretreated and then sent to a power plant to be used as a desulfurizer to purify the flue gas, and the purified flue gas is compressed again by the water circulation compressor and then is applied to the treatment of the mother liquor slurry;
the mother liquor slurry comprises the following main components: ca 2+ ：3.0~3.5mg/L、Mg 2+ ：1.0~1.5 mg/L、NaOH：6~8g/L、Na 2 CO 3 ：16~20g/L、Na 2 SO 4 :60 to 104 g/L, naCl:305 to 330g/L; the main component of the unsaturated original halogen is Ca 2+ ：700~750mg/L、Mg 2+ ：10~18mg/L、NaOH：0.002~0.005g/L、Na 2 CO 3 ：0.02~0.06g/L、Na 2 SO 4 :6 to 9 g/L, naCl:270 to 285g/L; wherein the dosage relationship between the mother liquor slurry and the unsaturated original halogen is as follows: CO in mother liquor slurry 3 2- And OH - The ratio of the total amount of substances to the amount of unsaturated orthohalogen substance Ca 2+ And Mg 2+ The quantity ratio of the total substances is a calculation formula: n = [ (nCO) 3 2- +nOH - /2)/(nCa 2+ +nMg 2+ )]，1.18≤n≤1.30。
2. The method for purifying salt mother liquor slurry by a flue gas method as claimed in claim 1, characterized in that: automatically controlling the carbonization reaction end point on line by a pH meter, taking the pH value of 8.5-9.0 as the carbonization reaction end point, sampling and detecting the index of the reaction mixed liquid, namely Ca 2+ ≤7mg/L，Mg 2+ ≤3mg/L。
3. The method for purifying salt mother liquor slurry by a flue gas method as claimed in claim 1, characterized in that: the main components of the flue gas after desulfurization and purification are as follows: SO (SO) 2 ≤35mg/Nm 3 ，NOx≤40mg/Nm 3 ，NH 3 ≤2mg/Nm 3 The smoke dust particles are less than or equal to 1.5mg/Nm 3 (ii) a The water circulation compressor secondarily purifies the main impurity components of the flue gas: SO (SO) 2 ≤15mg/Nm 3 ，NO x ≤10mg/Nm 3 ，NH 3 ≤0.01mg/Nm 3 Smoke dust is less than or equal to 0.1mg/Nm 3 。
4. The method for purifying salt mother liquor slurry by a flue gas method as claimed in claim 1, characterized in that: the main components of the filtrate obtained by separation are as follows: ca 2+ ：5.0~6.5mg/L、Mg 2+ ：1.5~2.0mg/L、NaOH：0.10~0.15g/L、Na 2 CO 3 ：0.3~0.5g/L、Na 2 SO 4 :9 to 15g/L, naCl:275 to 295g/L, and the SS of the suspension in the filtrate is less than or equal to 0.5mg/L; the ultrafiltration membrane is made of hollow fiber or inorganic ceramic.
5. The method for purifying salt mother liquor slurry by a flue gas method as claimed in claim 1, characterized in that: and (3) washing and filtering the solid separated by the ultrafiltration membrane, and collecting salt slurry with the particle size of 15 to 55um.
6. The method for purifying the mother liquor slurry for preparing salt by the flue gas method as claimed in claim 5, characterized in that: and collecting the obtained salt slurry for wet desulphurization of the flue gas, wherein the final pH value of the wet desulphurization is 5.4 to 5.8.
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