CN113149059A - Method and system for crystallization separation and sodium salt and potassium salt separation and purification of fly ash water washing liquid based on seed crystal method - Google Patents
Method and system for crystallization separation and sodium salt and potassium salt separation and purification of fly ash water washing liquid based on seed crystal method Download PDFInfo
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- CN113149059A CN113149059A CN202110414612.5A CN202110414612A CN113149059A CN 113149059 A CN113149059 A CN 113149059A CN 202110414612 A CN202110414612 A CN 202110414612A CN 113149059 A CN113149059 A CN 113149059A
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- 239000013078 crystal Substances 0.000 title claims abstract description 172
- 239000007788 liquid Substances 0.000 title claims abstract description 140
- 238000000746 purification Methods 0.000 title claims abstract description 96
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 93
- 238000000926 separation method Methods 0.000 title claims abstract description 92
- 238000005406 washing Methods 0.000 title claims abstract description 63
- 238000000034 method Methods 0.000 title claims abstract description 61
- 239000010881 fly ash Substances 0.000 title claims abstract description 56
- 238000002425 crystallisation Methods 0.000 title claims abstract description 45
- 230000008025 crystallization Effects 0.000 title claims abstract description 45
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 title claims abstract description 23
- 159000000000 sodium salts Chemical class 0.000 title claims abstract description 20
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims abstract description 238
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 202
- 239000010440 gypsum Substances 0.000 claims abstract description 142
- 229910052602 gypsum Inorganic materials 0.000 claims abstract description 142
- 239000001103 potassium chloride Substances 0.000 claims abstract description 119
- 235000011164 potassium chloride Nutrition 0.000 claims abstract description 119
- 239000012452 mother liquor Substances 0.000 claims abstract description 118
- 239000011780 sodium chloride Substances 0.000 claims abstract description 101
- 239000002002 slurry Substances 0.000 claims abstract description 88
- 238000001704 evaporation Methods 0.000 claims abstract description 82
- 150000003839 salts Chemical class 0.000 claims abstract description 79
- 230000008020 evaporation Effects 0.000 claims abstract description 70
- 238000011282 treatment Methods 0.000 claims abstract description 68
- 239000006228 supernatant Substances 0.000 claims abstract description 56
- 239000012267 brine Substances 0.000 claims abstract description 15
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims abstract description 15
- 239000003480 eluent Substances 0.000 claims abstract description 12
- 239000000047 product Substances 0.000 claims abstract description 11
- 238000002386 leaching Methods 0.000 claims abstract description 6
- 230000000382 dechlorinating effect Effects 0.000 claims abstract description 3
- 239000002562 thickening agent Substances 0.000 claims description 45
- 239000007790 solid phase Substances 0.000 claims description 12
- 230000018044 dehydration Effects 0.000 claims description 8
- 238000006297 dehydration reaction Methods 0.000 claims description 8
- 239000007787 solid Substances 0.000 claims description 8
- 238000006298 dechlorination reaction Methods 0.000 claims description 7
- 239000012530 fluid Substances 0.000 claims description 7
- 239000010413 mother solution Substances 0.000 claims description 7
- 239000007791 liquid phase Substances 0.000 claims description 6
- 239000012266 salt solution Substances 0.000 claims description 6
- 239000000243 solution Substances 0.000 claims description 6
- 238000003860 storage Methods 0.000 claims description 5
- 238000010828 elution Methods 0.000 claims description 4
- 239000002244 precipitate Substances 0.000 claims description 4
- 229920006395 saturated elastomer Polymers 0.000 claims description 4
- 125000004122 cyclic group Chemical group 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 2
- 239000000126 substance Substances 0.000 description 8
- 238000004056 waste incineration Methods 0.000 description 7
- 208000005156 Dehydration Diseases 0.000 description 6
- 239000002956 ash Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 239000011575 calcium Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000010813 municipal solid waste Substances 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000004568 cement Substances 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- 238000012958 reprocessing Methods 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- HGUFODBRKLSHSI-UHFFFAOYSA-N 2,3,7,8-tetrachloro-dibenzo-p-dioxin Chemical compound O1C2=CC(Cl)=C(Cl)C=C2OC2=C1C=C(Cl)C(Cl)=C2 HGUFODBRKLSHSI-UHFFFAOYSA-N 0.000 description 1
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 206010039509 Scab Diseases 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- 231100000357 carcinogen Toxicity 0.000 description 1
- 239000003183 carcinogenic agent Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000011552 falling film Substances 0.000 description 1
- 239000002920 hazardous waste Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000011268 retreatment Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/46—Sulfates
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/0018—Evaporation of components of the mixture to be separated
- B01D9/0031—Evaporation of components of the mixture to be separated by heating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/0036—Crystallisation on to a bed of product crystals; Seeding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/004—Fractional crystallisation; Fractionating or rectifying columns
- B01D9/0045—Washing of crystals, e.g. in wash columns
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
- B09B3/40—Destroying solid waste or transforming solid waste into something useful or harmless involving thermal treatment, e.g. evaporation
-
- 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
- C01D3/04—Chlorides
-
- 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
-
- 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
- C01D3/22—Preparation in the form of granules, pieces, or other shaped products
- C01D3/24—Influencing the crystallisation process
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/46—Sulfates
- C01F11/468—Purification of calcium sulfates
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D2009/0086—Processes or apparatus therefor
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Heat Treatment Of Water, Waste Water Or Sewage (AREA)
Abstract
The invention discloses a crystallization separation method of fly ash water washing liquid based on a seed crystal method and a separation and purification method and a system of sodium salt and potassium salt, wherein the method comprises the following steps: preheating the fly ash washing liquid and then carrying out evaporation concentration treatment; crystallizing and layering the concentrated feed liquid in an evaporation crystallizer to obtain crystal slurry, strong brine and salt slurry; separating the crystal slurry in a gypsum separator to obtain crystal gypsum and gypsum mother liquor; the salt slurry is processed in a sodium chloride separation and purification device to obtain sodium chloride crystal salt, supernatant and sodium chloride mother liquor; and treating the supernatant in a potassium chloride separation and purification device to obtain potassium chloride crystals, potassium chloride crystal salt and potassium chloride mother liquor. The method and the system can effectively prevent the evaporator from scaling, ensure the stable operation of the system and improve the quality of salt production; dechlorinating the crystallized gypsum by using a water washing or leaching mode, and recovering a gypsum product; the generated condensed water and gypsum eluent are recycled; in the process of evaporation and crystallization, mother liquor is circularly concentrated and evaporated, so that the salt yield is improved.
Description
Technical Field
The invention relates to a treatment method and a treatment system for waste incineration fly ash, in particular to a method and a treatment system for washing, crystallizing and separating fly ash, separating and purifying sodium salt and potassium salt based on a seed crystal method, belonging to the field of retreatment and utilization of waste incineration fly ash.
Background
The waste incineration fly ash contains a large amount of chloride ions, and is listed as solid hazardous waste by the nation due to the fact that the waste incineration fly ash is rich in heavy metal inorganic harmful substances and high-concentration dioxin organic carcinogens (code HW 18). A technology for treating the fly ash generated by burning garbage by cement kiln features that the fly ash generated by burning garbage is washed by water, the residual fly ash is dried to obtain cement, and the waste water generated by washing is collected and treated to meet the requirement of water quality for evaporating crystallization.
The water washing pretreatment can transfer soluble substances (potassium, sodium and chloride ions) in the fly ash into water washing liquid. The fly ash water washing liquid contains about 6 to 15 weight percent of potassium and sodium salts, but Chinese potassium salt resources are relatively scarce, and the potassium salt and the sodium salt are prepared from the fly ash water washing liquid by an evaporative crystallization technology, so that the vacancy of the potassium salt in China is relieved. In the evaporation crystallization process, sodium salt crystals with high content are separated out, then mother liquor is continuously refluxed to enrich potassium salt, the potassium salt can be separated out after the potassium salt is saturated, and the mixed salt of the sodium salt and the potassium salt is obtained.
The Chinese invention patent (CN 108191135A) discloses a system and a method for preparing salt by evaporating waste incineration fly ash or kiln ash water washing liquid, which comprises a falling film evaporation unit, a forced circulation crystallization unit and an equal gradient cooling crystallization unit; each unit is internally provided with an independent condensed water collecting system, a noncondensable gas treatment system and a mechanical vapor recompression system; and a forced circulation crystallization unit is provided with a separation device, and potassium salt and sodium salt are separated. The invention provides an important way for the simple operation of evaporating the waste incineration fly ash or kiln ash water washing liquid to prepare salt, improving the treatment effect and prolonging the service life of equipment, and is beneficial to the resource utilization of the waste incineration fly ash or kiln ash water washing pretreatment product and beneficial components carried in the water washing liquid.
Aiming at the evaporation salt making process of the fly ash or kiln ash washing liquid with high salt content, the prior art realizes that equipment is not easy to scab to a certain extent, the product salt quality is good, and the system operation is stable, but the components of the fly ash washing liquid are complex and the salt concentration is high, the feed liquid is continuously and circularly evaporated in the evaporation process, salt crystal grains in the concentrated feed liquid can be attached to the surface of an evaporator, the heat transfer is uneven, the heat transfer efficiency is low, energy waste can be caused, the regular shutdown and cleaning are needed, and the production efficiency is seriously influenced.
Disclosure of Invention
One of the purposes of the invention is to provide a fly ash washing crystallization separation and sodium salt and potassium salt separation and purification method based on a seed crystal method;
one of the purposes of the invention is to provide a treatment system for realizing the fly ash washing crystallization separation and sodium salt and potassium salt separation and purification method based on the seed crystal method;
the above object of the present invention is achieved by the following technical solutions:
the invention firstly provides a crystallization separation method of fly ash water washing liquid based on a seed crystal method and a separation and purification method of sodium salt and potassium salt, which comprises the following steps: (1) preheating the fly ash water washing liquid in a preheater to obtain preheated fly ash water washing liquid; (2) evaporating and concentrating the preheated fly ash water washing liquid in a forced circulation heat exchanger to obtain concentrated feed liquid; (3) crystallizing and layering the concentrated feed liquid in an evaporation crystallizer to obtain crystal slurry, strong brine and salt slurry; (4) separating the crystal slurry from the feed liquid in a gypsum separator to obtain crystal gypsum and gypsum mother liquor; purifying and separating the salt slurry in a sodium chloride separation and purification device to obtain sodium chloride crystal salt, supernatant and sodium chloride mother liquor; separating and purifying the supernatant in a potassium chloride separation and purification device to obtain potassium chloride crystals, potassium chloride crystal salts and potassium chloride mother liquor; (5) conveying the concentrated salt solution obtained in the step (3), the gypsum mother solution obtained in the step (4) and the sodium chloride mother solution into a forced circulation heat exchanger for evaporation and concentration treatment, and then repeating the treatment steps (3) - (4); and (4) conveying the sodium chloride mother liquor and the potassium chloride mother liquor obtained in the step (4) to a mother liquor tank for storage.
In a preferred embodiment of the invention, in the step (1), the purified fly ash water washing liquid is preheated by a multi-stage preheater to obtain a preheated water washing liquid at 90-110 ℃, and condensed water generated in the preheater is used as elution water of a gypsum dewatering device.
As a preferred embodiment of the present invention, the condensed water produced in the forced circulation heat exchanger in the step (2) is supplied to the preheating water of the preheater in the step (1), wherein the temperature of the condensed water is 80-100 ℃.
As a preferred embodiment of the invention, when the preheated fly ash water washing liquid is subjected to evaporation concentration treatment in the forced circulation heat exchanger in the step (2), the temperature of the forced circulation heat exchanger is controlled to be 100-120 ℃.
As a preferred embodiment of the invention, gypsum seed crystals, preferably 15-30g/L gypsum seed crystals, are added when the concentrated feed liquid in step (3) is sent into an evaporative crystallizer for evaporative crystallization. By utilizing the principle that the affinity of the same substance is greater than that of different substances, the solid gypsum particles are uniformly dispersed in the feed liquid in the evaporative crystallizer, and Ca in the feed liquid2+And SO4 2-Will first agglomerate on the solid gypsum nuclei to form crystal precipitates.
As a preferred embodiment of the invention, the concentrated brine obtained in step (3) is subjected to evaporation concentration treatment twice and then returned to the evaporation crystallizer for crystallization and layering treatment, and the circulation is repeated for a plurality of times for circulation evaporation concentration and evaporation crystallization treatment.
As a preferred embodiment of the present invention, in the step (3), dechlorinating the crystallized gypsum to obtain a gypsum product and a gypsum eluate, and conveying the gypsum eluate after being processed by the purifying device to the forced circulation heat exchanger for evaporation and concentration; preferably, the dechlorination treatment mode is gypsum water washing or leaching dechlorination, and the gypsum eluent is purified and then conveyed to the forced circulation heat exchanger.
As a preferred embodiment of the present invention, the sodium chloride separating and purifying apparatus in step (4) is composed of a first thickener and a first centrifuge which are connected in sequence; wherein, the salt slurry enters a first thickener, and is purified and layered to obtain supernatant and sodium chloride crystal slurry; and separating the sodium chloride crystal slurry by using a first centrifugal machine to obtain sodium chloride crystal salt and sodium chloride mother liquor.
As a preferred specific embodiment of the present invention, the potassium chloride separation and purification apparatus in step (4) is composed of a supernatant tank, a crystallization tank, a second thickener and a second centrifuge, which are connected in sequence, wherein the supernatant enters the supernatant tank, enters the crystallization tank when the potassium chloride solution is saturated, and is cooled to 10-50 ℃ in the crystallization tank to precipitate potassium chloride crystals; and (3) feeding the feed liquid in the crystallization tank into a second thickener to obtain potassium chloride crystal slurry and potassium chloride mother liquor, and separating the potassium chloride crystal slurry by using a second centrifuge to obtain potassium chloride crystal salt and potassium chloride mother liquor.
In a preferred embodiment of the invention, the mother liquor stored in the mother liquor tank is treated by a mother liquor purification device and then is conveyed to a forced circulation heat exchanger for further evaporation and concentration treatment.
The above-described process can be carried out by those skilled in the art using various conventional apparatuses for fly ash treatment and reuse, which are easily implemented by those skilled in the art.
The invention provides a treatment system for realizing the crystallization separation of fly ash water washing liquid and the separation and purification method of sodium salt and potassium salt based on a seed crystal method, which comprises a multi-stage preheater, a first forced circulation heat exchanger, a gypsum seed crystal tank, an evaporation crystallizer, a gypsum separator, a gypsum dehydration device, a sodium chloride separation and purification device and a potassium chloride separation and purification device;
the multi-stage preheater is provided with a fly ash washing liquid inlet, a preheated water inlet, a condensed water outlet and a discharge hole; the first forced circulation heat exchanger is provided with a feed liquid inlet, a condensed water outlet and an evaporated liquid outlet; the gypsum seed crystal tank is provided with a gypsum seed crystal inlet and a gypsum seed crystal outlet; the evaporation crystallizer is provided with an evaporation liquid inlet, a gypsum seed crystal inlet, a crystal slurry outlet, a salt slurry outlet and a strong brine outlet; the gypsum separator is provided with a crystal slurry inlet, a solid phase outlet and a mother liquid outlet; the gypsum dehydration device is provided with a solid phase inlet, a water inlet, a gypsum outlet and a liquid phase outlet; the sodium chloride separation and purification device is provided with a salt slurry inlet, a supernatant outlet, a sodium chloride crystallized salt outlet and a sodium chloride mother liquor outlet; the potassium chloride separation and purification device is provided with a supernatant inlet, a potassium chloride crystal outlet, a potassium chloride crystal salt outlet and a potassium chloride mother liquor outlet;
the discharge port of the multi-stage preheater is connected with a feed liquid inlet of the first forced circulation heat exchanger, an evaporating liquid outlet of the first forced circulation heat exchanger is connected with an evaporating liquid inlet of the evaporative crystallizer, and a gypsum seed crystal outlet of the gypsum seed crystal tank is connected with a gypsum seed crystal inlet of the evaporative crystallizer; the crystal slurry outlet of the evaporation crystallizer is connected with the crystal slurry inlet of the gypsum separator, and the solid phase outlet of the gypsum separator is connected with the solid phase inlet of the gypsum dewatering device; the salt slurry outlet of the evaporation crystallizer is connected with the salt slurry inlet of the sodium chloride separation and purification device, and the supernatant outlet of the sodium chloride separation and purification device is connected with the supernatant inlet of the potassium chloride separation and purification device.
As a preferred embodiment of the present invention, the preheated water inlet of the multi-stage preheater is connected to the condensed water outlet of the first forced circulation heat exchanger; and a strong brine outlet of the evaporation crystallizer and a mother liquor outlet of the gypsum separator are connected with a feed liquid inlet of the first forced circulation heat exchanger.
In a preferred embodiment of the invention, the liquid phase outlet of the gypsum dewatering device is connected with the inlet of the purification treatment device, and the outlet of the purification treatment device is connected with the feed liquid inlet of the first forced circulation heat exchanger.
As a preferred embodiment of the present invention, a sodium chloride mother liquor outlet of the sodium chloride separation and purification device and a potassium chloride mother liquor outlet of the potassium chloride separation and purification device are connected to a feed liquor inlet of the first forced circulation heat exchanger through a mother liquor return line; further preferably, the mother liquor tank and the mother liquor purification treatment device are sequentially connected with the liquid return pipeline, wherein a sodium chloride mother liquor outlet of the sodium chloride separation and purification device and a potassium chloride mother liquor outlet of the potassium chloride separation and purification device are connected with an inlet of the mother liquor tank, an outlet of the mother liquor tank is connected with an inlet of the mother liquor purification treatment device, and an outlet of the mother liquor purification treatment device is connected with a feed liquid inlet of the forced circulation heat exchanger through the mother liquor return pipeline.
As a preferred embodiment of the present invention, the sodium chloride separation and purification apparatus comprises a first thickener and a first centrifuge which are connected in sequence; the first thickener is provided with a feeding port, a supernatant outlet and a sodium chloride crystal slurry outlet; the first centrifugal machine is provided with a sodium chloride crystal slurry inlet, a sodium chloride crystal salt outlet and a sodium chloride mother liquor outlet; the supernatant outlet of the first thickener is connected with the inlet of the supernatant tank, the sodium chloride crystal slurry outlet of the first thickener is connected with the sodium chloride crystal slurry inlet of the first centrifuge, and the sodium chloride mother liquor outlet of the first centrifuge is connected with the inlet of the mother liquor tank;
the potassium chloride separation and purification device comprises a supernatant fluid tank, a crystallizing tank, a second thickener and a second centrifuge which are connected in sequence; the second thickener is provided with a material liquid inlet, a potassium chloride crystal slurry outlet and a potassium chloride mother liquid outlet, and the second centrifuge is provided with a potassium chloride crystal slurry inlet, a potassium chloride crystal salt outlet and a potassium chloride mother liquid outlet; and a discharge port of the supernatant tank is connected with a feed port of the crystallizing tank, a feed liquid outlet of the crystallizing tank is connected with a feed liquid inlet of the second thickener, and a potassium chloride crystal slurry discharge port of the second thickener is connected with a potassium chloride crystal slurry feed port of the second centrifuge.
As a preferred embodiment of the present invention, the potassium chloride mother liquor outlet of the second thickener and the potassium chloride mother liquor outlet of the second centrifuge are connected to the inlet of the mother liquor tank.
The invention effectively utilizes the gypsum seed crystal method in the evaporative crystallization process of the fly ash washing liquid, and solves the problems of easy scaling of equipment, low yield of crystallized salt and poor quality in the evaporative crystallization process. The process of preparing salt by evaporating the water washing liquid based on the gypsum crystal seed method can effectively prevent the evaporator from scaling, reduce the energy consumption of mass and heat transfer and ensure the stable operation of the system; sulfate radicals and calcium ions in the washing liquid are attached to the gypsum seed crystal to form crystallized gypsum, so that the content of sulfate radicals in the crystallized salt is effectively reduced, and the quality of the produced salt is improved; according to the invention, the crystal gypsum is subjected to water washing treatment, soluble impurities in the gypsum are removed, the added value of a gypsum product is improved, and the gypsum eluent and the mother liquor generated in the crystallization separation process return to the forced circulation heat exchange device to be continuously concentrated and evaporated, so that zero discharge of wastewater is realized in the technical process; in addition, the forced circulation heat exchanger is adopted in the evaporation concentration process, so that the scaling phenomenon of equipment in the evaporation concentration process is reduced.
Compared with the prior art, the invention has the following advantages and prominent technical effects:
1. the evaporation crystallization process of the fly ash water washing liquid based on the gypsum seed crystal method can effectively prevent the evaporator from scaling and ensure the stable operation of the system; and the technical problem that sulfate radicals influence the quality of the crystal salt is solved, and the quality of the produced salt can be improved.
2. The crystal gypsum is dechlorinated by using a water washing or leaching mode, so that the gypsum product can be recovered, the product value is improved, and the economic benefit is good.
3. The condensed water and the gypsum eluent generated in the process are recycled, so that the cost is saved, and the energy consumption is reduced.
4. In the process of evaporation and crystallization, mother liquor is circularly concentrated and evaporated, so that the salt yield is improved.
Drawings
FIG. 1 is a process flow diagram of one embodiment of the process of the present invention.
FIG. 2 is a process flow diagram of another embodiment of the process of the present invention.
FIG. 3 is a schematic diagram of the components and connections of the devices in an embodiment of the present invention.
FIG. 4 is another schematic diagram of the components and connections of the devices in another embodiment of the present invention.
FIG. 5 is a schematic view of the connection relationship between the evaporative crystallizer and the first and second forced circulation heat exchangers.
Reference numerals: 1-a multistage preheater, 2-a first forced circulation heat exchanger, 3-a gypsum seed crystal tank, 4-an evaporative crystallizer, 5-a gypsum separator, 6-a gypsum dehydration device, 7-a sodium chloride separation and purification device, 8-a potassium chloride separation and purification device, 9-a purification treatment device, 10-a first thickener, 11-a first centrifuge, 12-a supernatant fluid tank, 13-a crystallization tank, 14-a second thickener, 15-a second centrifuge, 16-a mother fluid tank, 17-a mother fluid purification treatment device and 18-a second forced circulation heat exchanger.
Detailed Description
The invention will be further described with reference to specific embodiments, and the advantages and features of the invention will become apparent as the description proceeds. It is to be understood that the described embodiments are exemplary only and are not limiting upon the scope of the invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention, and that such changes and modifications may be within the scope of the invention.
In the description of the embodiments of the present application, it should be noted that the indication of orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship which is usually placed when the product of the application is used, or the orientation or positional relationship which is usually understood by those skilled in the art, or the orientation or positional relationship which is usually placed when the product of the application is used, and is only for the convenience of describing the application and simplifying the description, but does not indicate or imply that the indicated device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the application. In the description of the embodiments of the present application, it should also be noted that, unless otherwise explicitly stated or limited, the terms "disposed," "mounted," and "connected" are to be construed broadly, and may for example be fixedly connected, detachably connected, or integrally connected; may be directly connected or indirectly connected through an intermediate. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.
In the description of embodiments of the present application, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Referring to fig. 1, the invention firstly provides a crystallization separation and sodium salt and potassium salt separation and purification method of fly ash water washing liquid based on a seed crystal method, which comprises the following steps: (1) preheating the fly ash water washing liquid in a preheater to obtain preheated fly ash water washing liquid; (2) evaporating and concentrating the preheated fly ash water washing liquid in a forced circulation heat exchanger to obtain concentrated feed liquid; (3) crystallizing and layering the concentrated feed liquid in an evaporation crystallizer to obtain crystal slurry, strong brine and salt slurry; (4) separating the crystal slurry from the feed liquid in a gypsum separator to obtain crystal gypsum and gypsum mother liquor; purifying and separating the salt slurry in a sodium chloride separation and purification device to obtain sodium chloride crystal salt, supernatant and sodium chloride mother liquor; separating and purifying the supernatant in a potassium chloride separation and purification device to obtain potassium chloride crystals, potassium chloride crystal salts and potassium chloride mother liquor; (5) conveying the concentrated salt solution obtained in the step (3), the gypsum mother solution obtained in the step (4) and the sodium chloride mother solution into a forced circulation heat exchanger for evaporation and concentration treatment, and then repeating the treatment steps (3) - (4); and (4) conveying the sodium chloride mother liquor and the potassium chloride mother liquor obtained in the step (4) to a mother liquor tank for storage.
In a preferred embodiment of the invention, the fly ash water washing liquid purified in the step (1) is preheated by a multi-stage preheater to obtain a preheated water washing liquid at 90-110 ℃, condensed water generated in the preheater is used as elution water of a gypsum dewatering device, and the condensed water generated in the forced circulation heat exchanger in the step (2) is supplied to the preheated water of the preheater in the step (1), wherein the temperature of the condensed water is 80-100 ℃.
As a preferred embodiment of the invention, when the preheated fly ash water washing liquid is subjected to evaporation concentration treatment in the forced circulation heat exchanger in the step (2), the temperature of the forced circulation heat exchanger is controlled to be 100-120 ℃.
As a preferred embodiment of the invention, gypsum seed crystals, preferably 15-30g/L gypsum seed crystals, are added when the concentrated feed liquid in step (3) is sent into an evaporative crystallizer for evaporative crystallization. By utilizing the principle that the affinity of the same substance is greater than that of different substances, the solid gypsum particles are uniformly dispersed in the feed liquid in the evaporative crystallizer, and Ca in the feed liquid2+And SO4 2-Will first agglomerate on the solid gypsum nuclei to form crystal precipitates.
Referring to fig. 2 and 5, in an embodiment of the present invention, the concentrated brine obtained in step (3) is subjected to two evaporation concentration treatments in the second forced circulation device 18 and the first forced circulation device 2 in sequence, and then returned to the evaporation crystallizer 4 for crystallization and layering treatment, and thus the circulation is repeated for multiple times of circulation evaporation concentration and evaporation crystallization treatments.
As a more preferable embodiment of the present invention, in the step (3), the crystalline gypsum is dechlorinated to obtain a gypsum product and a gypsum eluate, and the gypsum eluate is processed by the purifying device and then is sent to the first forced circulation heat exchanger 2 or the second forced circulation device 18 for evaporation and concentration; preferably, the dechlorination treatment mode is gypsum water washing or leaching dechlorination, and the gypsum eluent is purified and then conveyed to the forced circulation heat exchanger.
Referring to fig. 4, according to an embodiment of the present invention, the sodium chloride separating and purifying apparatus 7 in step (4) is composed of a first thickener 10 and a first centrifuge 11 connected in series; wherein, the salt slurry enters a first thickener 11 to obtain supernatant and sodium chloride crystal slurry after purification and layering treatment; the sodium chloride crystal slurry is separated by a first centrifuge 11 to obtain sodium chloride crystal salt and sodium chloride mother liquor.
Referring to fig. 4, the potassium chloride separating and purifying device 8 in step (4) is composed of a supernatant tank 12, a crystallizing tank 13, a second thickener 14 and a second centrifuge 15, which are connected in sequence, wherein the supernatant enters the supernatant tank 12, enters the crystallizing tank 13 when the potassium chloride solution is saturated, and potassium chloride crystals are separated out when the potassium chloride solution is cooled to 10-50 ℃ in the crystallizing tank 13; and (3) feeding the feed liquid in the crystallization tank 13 into a second thickener 14 to obtain potassium chloride crystal slurry and potassium chloride mother liquor, and separating the potassium chloride crystal slurry by a second centrifugal machine 15 to obtain potassium chloride crystal salt and potassium chloride mother liquor.
In a specific embodiment of the present invention, the mother liquor stored in the mother liquor tank 16 is treated by the mother liquor purification device 17 and then sent to the first forced circulation heat exchanger 2 for further evaporation and concentration.
Referring to fig. 3, the treatment system for realizing the crystallization separation of the fly ash water washing liquid and the separation and purification method of sodium salt and potassium salt based on the seed crystal method provided by the invention comprises a multi-stage preheater 1, a first forced circulation heat exchanger 2, a gypsum seed crystal tank 3, an evaporation crystallizer 4, a gypsum separator 5, a gypsum dehydration device 6, a sodium chloride separation and purification device 7 and a potassium chloride separation and purification device 8; the multi-stage preheater 1 is provided with a fly ash washing liquid inlet, a preheated water inlet, a condensed water outlet and a discharge hole; the first forced circulation heat exchanger 2 is provided with a feed liquid inlet, a condensed water outlet and an evaporated liquid outlet; the gypsum seed crystal tank 3 is provided with a gypsum seed crystal inlet and a gypsum seed crystal outlet; the evaporation crystallizer 4 is provided with an evaporation liquid inlet, a gypsum seed crystal inlet, a crystal slurry outlet, a salt slurry outlet and a strong brine outlet; the gypsum separator 5 is provided with a crystal slurry inlet, a solid phase outlet and a mother liquid outlet; the gypsum dewatering device 6 is provided with a solid phase inlet, a water inlet, a gypsum outlet and a liquid phase outlet; the sodium chloride separation and purification device 7 is provided with a salt slurry inlet, a supernatant outlet, a sodium chloride crystallized salt outlet and a sodium chloride mother liquor outlet; the potassium chloride separation and purification device 8 is provided with a supernatant inlet, a potassium chloride crystal outlet, a potassium chloride crystal salt outlet and a potassium chloride mother liquor outlet;
wherein, the discharge hole of the multi-stage preheater 1 is connected with the feed liquid inlet of the first forced circulation heat exchanger 2, the evaporation liquid outlet of the first forced circulation heat exchanger 2 is connected with the evaporation liquid inlet of the evaporative crystallizer 4, and the gypsum seed crystal outlet of the gypsum seed crystal tank 3 is connected with the gypsum seed crystal inlet of the evaporative crystallizer 4; a crystal slurry outlet of the evaporative crystallizer 4 is connected with a crystal slurry inlet of a gypsum separator 5, and a solid phase outlet of the gypsum separator 5 is connected with a solid phase inlet of a gypsum dewatering device 6; the salt slurry outlet of the evaporation crystallizer 4 is connected with the salt slurry inlet of the sodium chloride separation and purification device 7, and the supernatant outlet of the sodium chloride separation and purification device 7 is connected with the supernatant inlet of the potassium chloride separation and purification device 8.
In a preferred embodiment, the preheated water inlet of the multi-stage preheater 1 is connected to the condensed water outlet of the first forced circulation heat exchanger 2; a strong brine outlet of the evaporation crystallizer 4 and a mother liquor outlet of the gypsum separator 5 are connected with a feed liquid inlet of the first forced circulation heat exchanger 2; the liquid phase outlet of the gypsum dewatering device 6 is connected with the inlet of the purification treatment device 9, and the outlet of the purification treatment device 9 is connected with the feed liquid inlet of the first forced circulation heat exchanger 2.
Referring to fig. 2 and 4, in a preferred embodiment of the present invention, the sodium chloride mother liquor outlet of the sodium chloride separation and purification device 7 and the potassium chloride mother liquor outlet of the potassium chloride separation and purification device 8 are connected to the feed liquor inlet of the first forced circulation heat exchanger 2 through mother liquor return lines; further preferably, a mother liquor return pipeline is sequentially connected with a mother liquor tank 16 and a mother liquor purification treatment device 17, wherein a sodium chloride mother liquor outlet of the sodium chloride separation and purification device 7 and a potassium chloride mother liquor outlet of the potassium chloride separation and purification device 8 are connected with an inlet of the mother liquor tank 16, an outlet of the mother liquor tank 16 is connected with an inlet of the mother liquor purification treatment device 17, and an outlet of the mother liquor purification treatment device 17 is connected with a feed liquor inlet of the first forced circulation heat exchanger 2 through the mother liquor return pipeline.
Referring to fig. 4, in an embodiment of the present invention, the sodium chloride separation and purification apparatus 7 includes a first thickener 10 and a first centrifuge 11 connected in sequence; wherein, the first thickener 10 is provided with a feeding port, a supernatant outlet and a sodium chloride crystal slurry outlet; the first centrifugal machine 11 is provided with a sodium chloride crystal slurry inlet, a sodium chloride crystal salt outlet and a sodium chloride mother liquor outlet; a supernatant outlet of the first thickener 10 is connected with an inlet of a supernatant tank 12, a sodium chloride crystal slurry outlet of the first thickener 10 is connected with a sodium chloride crystal slurry inlet of a first centrifuge 11, and a sodium chloride mother liquor outlet of the first centrifuge 11 is connected with an inlet of a mother liquor tank 16;
the potassium chloride crystallization separation and purification device 8 comprises a supernatant tank 12, a crystallization tank 13, a second thickener 14 and a second centrifuge 15 which are connected in sequence; the supernatant tank 12 is provided with a supernatant inlet and a discharge outlet, the crystallizing tank is provided with a feed inlet, a potassium chloride crystal liquid discharge outlet and a feed liquid outlet, the second thickener 14 is provided with a feed liquid inlet, a potassium chloride crystal liquid discharge outlet and a potassium chloride mother liquid discharge outlet, and the second centrifuge 15 is provided with a potassium chloride crystal liquid feed inlet, a potassium chloride crystal salt outlet and a potassium chloride mother liquid outlet; the discharge port of the supernatant tank 12 is connected with the feed inlet of the crystallizer, the feed liquid outlet of the crystallizer is connected with the feed liquid inlet of the second thickener 14, and the potassium chloride crystal slurry discharge port of the second thickener 14 is connected with the potassium chloride crystal slurry feed inlet of the second centrifuge 15.
And a potassium chloride mother liquor discharge port of the second thickener 14 and a potassium chloride mother liquor outlet of the second centrifuge 15 are connected with an inlet of a mother liquor tank.
Various devices or apparatuses used in the invention are conventional devices in the technology of solid waste reprocessing or garbage fly ash reprocessing, and the devices can be purchased commercially and are all suitable for the invention; in addition, the related literature also discloses new devices with improved devices, and better technical effects can be achieved by using the new devices with improved devices, such as: a multi-stage elution separation device (CN 204848668U, the name of the utility model is a fly ash washing device); multistage filter device (CN 205627217U, utility model name: quick-open type multi-medium filter).
The method and system of the present invention are further described below in conjunction with specific embodiments.
Example 1 fly ash washing crystallization separation System based on seed Crystal method and sodium salt and Potassium salt separation and purification
Referring to fig. 1 and fig. 3, this embodiment provides a separation system for water washing crystallization of fly ash and a separation and purification method for sodium salt and potassium salt based on a seed crystal method, which includes:
preheating water washing liquid: preheating the purified fly ash water washing liquid in a multi-stage preheater 1 to obtain a preheated feed liquid at 90-110 ℃, wherein the condensed water generated in the multi-stage preheating process is used as dechlorination water for a gypsum dewatering device.
Step (2) evaporation and concentration: pumping the preheated feed liquid into a forced circulation heat exchanger 2 through a feed pipe, carrying out evaporation concentration treatment on the preheated feed liquid in the forced circulation heat exchanger 2 to obtain concentrated feed liquid, controlling the temperature of the heat exchanger to be 100-120 ℃, wherein the solid-to-liquid ratio of the feed liquid is more than or equal to 30%, and supplying condensate water generated in the forced circulation heat exchange process in the step (2) to a multi-stage preheater for preheating, wherein the temperature of the condensate water is 80-100 ℃;
and (3) crystallizing by using a seed crystal method: feeding the concentrated feed liquid into an evaporation crystallizer 4, and crystallizing and layering in the evaporation crystallizer 4 to obtain crystal slurry with the salt content of 30-60 wt%, concentrated salt solution and concentrated salt solution with the salt content of 30-60 wt%The salt slurry of (1). Wherein 15-30g/L gypsum seed crystal is added into the evaporative crystallizer, and solid gypsum particles are uniformly dispersed in feed liquid in the evaporative crystallizer by utilizing the principle that the affinity of the same substance is greater than that of different substances, and Ca in the feed liquid2+And SO4 2-Will first agglomerate on the solid gypsum nuclei to form gypsum crystals and precipitate out.
The strong brine is conveyed to a forced circulation heat exchanger 2 to continue evaporation and concentration treatment;
step (4), gypsum separation: the crystal slurry in the evaporative crystallizer 2 enters a gypsum separator 5, gypsum and feed liquid are separated to obtain crystalline gypsum with the water content of not more than 60 wt%, and the separated feed liquid is conveyed to a forced circulation heat exchanger 2 to be continuously subjected to evaporative concentration treatment; and (3) feeding the crystallized gypsum into a gypsum dehydration device 6 for treatment, preferably selecting a gypsum water washing or leaching mode to obtain gypsum and gypsum eluent, and feeding the gypsum eluent into the forced circulation heat exchanger 2 for continuous evaporation and concentration treatment.
And (5) separating sodium chloride: the salt slurry in the evaporation crystallizer 4 enters a sodium chloride separation and purification device 7, and the crystallized salt and the feed liquid are purified and separated to obtain sodium chloride crystallized salt with the water content not more than 6 wt%, supernatant and sodium chloride mother liquor;
step (6), separating potassium chloride crystals, namely sending the supernatant obtained in the step (5) into a potassium chloride crystal separation and purification device 8, and performing crystallization, purification and separation treatment to obtain potassium chloride crystal salt with the water content of not more than 6 wt% and a potassium chloride mother solution;
and (4) conveying the sodium chloride mother liquor generated in the step (5) and the potassium chloride mother liquor generated in the step (6) to the first forced circulation heat exchanger 2 to continue evaporation and concentration treatment.
Example 2 fly ash washing crystallization separation system based on seed crystal method and sodium salt and potassium salt separation and purification
Referring to fig. 2 and 4, the following steps are performed:
a. the purified fly ash water washing liquid enters a multi-stage preheater 1 for preheating.
b. And (4) evaporating and concentrating the preheated feed liquid in the forced circulation heat exchanger 2 to obtain concentrated feed liquid.
c. Crystallizing and layering the concentrated feed liquid in an evaporation crystallizer 4 to obtain crystal slurry with the salt content of 30-60 wt%, concentrated salt solution and salt slurry with the salt content of 30-60 wt%.
d. Adding 15-30g/L gypsum seed crystal into an evaporation crystallizer,
e. the crystal slurry enters a gypsum separator 5 for separation treatment to obtain crystallized gypsum and gypsum mother liquor with the water content not more than 60 wt%; and (3) carrying out gypsum dehydration treatment on the crystallized gypsum, and conveying the gypsum eluent after the treatment of the purification treatment device 9 to the first forced circulation heat exchanger 2 for continuous evaporation and concentration treatment.
f. And (3) separating sodium chloride: the salt slurry in the evaporation crystallizer 4 enters a first thickener 10, and after purification and layering treatment, supernatant and sodium chloride crystal slurry are obtained; the sodium chloride crystal slurry is separated by a first centrifuge 11 to obtain sodium chloride crystal salt and sodium chloride mother liquor. The mother liquor of sodium chloride is transferred to a mother liquor tank 16 for storage.
g. And (3) potassium chloride separation: supernatant separated from the first thickener 10 enters a supernatant tank 12, potassium chloride solution in the supernatant tank 12 reaches saturation and then enters a crystallizing tank 13, and potassium chloride crystals are separated out when the temperature is cooled to 10-50 ℃ in the crystallizing tank 13; the feed liquid in the crystallizing tank 13 enters a second thickener 14 to obtain mother liquid and potassium chloride crystal slurry; separating the potassium chloride crystal slurry by a second centrifugal machine 15 to obtain potassium chloride crystal salt and potassium chloride mother liquor; conveying the potassium chloride mother liquor separated by the second thickener 14 and the second centrifuge 15 to a mother liquor tank 16 for storage; the mother liquor stored in the mother liquor tank 16 is treated by the mother liquor purification treatment device 17 and then is conveyed to the first forced circulation heat exchanger 2 for continuous evaporation and concentration treatment.
Example 3 fly ash washing crystallization separation System based on seed Crystal method and sodium salt and Potassium salt separation and purification
Referring to fig. 5, the difference from embodiment 2 is that: the concentrated brine obtained from the evaporator-crystallizer 4 passes through the second forced circulation heat exchanger 18 and the first forced circulation heat exchanger 2 in sequence, is evaporated and concentrated twice, and then returns to the evaporator-crystallizer 4 for multiple times of forced circulation evaporation and concentration treatment.
Claims (10)
1. A crystallization separation and sodium salt and potassium salt separation and purification method of fly ash water washing liquid based on a seed crystal method comprises the following steps: (1) preheating the fly ash water washing liquid in a preheater to obtain preheated fly ash water washing liquid; (2) evaporating and concentrating the preheated fly ash water washing liquid in a forced circulation heat exchanger to obtain concentrated feed liquid; (3) crystallizing and layering the concentrated feed liquid in an evaporation crystallizer to obtain crystal slurry, strong brine and salt slurry; (4) separating the crystal slurry from the feed liquid in a gypsum separator to obtain crystal gypsum and gypsum mother liquor; purifying and separating the sodium chloride crystal salt and the feed liquid in a sodium chloride separation and purification device to obtain sodium chloride crystal salt, supernatant and sodium chloride mother liquid; separating and purifying the supernatant in a potassium chloride separation and purification device to obtain potassium chloride crystals, potassium chloride crystal salts and potassium chloride mother liquor; (5) conveying the concentrated salt solution obtained in the step (3), the gypsum mother solution obtained in the step (4) and the sodium chloride mother solution into a forced circulation heat exchanger for evaporation and concentration treatment, and then repeating the treatment steps (3) - (4); and (4) conveying the sodium chloride mother liquor and the potassium chloride mother liquor obtained in the step (4) to a mother liquor tank for storage.
2. The separation and purification method according to claim 1, wherein in the step (1), the purified fly ash water washing liquid is subjected to preheating treatment by a multi-stage preheater to obtain a preheated water washing liquid at 90-110 ℃, and condensed water generated in the preheater is used as elution water of a gypsum dewatering device; the condensed water generated by the forced circulation heat exchanger in the step (2) is supplied to the preheating water of the preheater in the step (1), wherein the temperature of the condensed water is 80-100 ℃; and (3) in the step (2), when the preheated fly ash water washing liquid is subjected to evaporation concentration treatment in the forced circulation heat exchanger, controlling the temperature of the forced circulation heat exchanger to be 100-120 ℃.
3. The separation and purification method according to claim 1, wherein the concentrated feed liquid in the step (3) is crystallized by adding gypsum seed crystals when the concentrated feed liquid is fed into the evaporative crystallizer for evaporative crystallization, preferablyAdding 15-30g/L gypsum seed crystal to make Ca in the feed liquid2+And SO4 2-Will first agglomerate on the solid gypsum nuclei to form crystal precipitates.
4. The separation and purification method according to claim 1, wherein the concentrated brine obtained in step (3) is subjected to evaporation concentration twice and then returned to the evaporation crystallizer for crystallization and layering treatment, and the cyclic evaporation concentration and evaporation crystallization treatment are repeatedly performed for a plurality of times;
dechlorinating the crystallized gypsum to obtain a gypsum product and gypsum eluent, and conveying the gypsum eluent to a forced circulation heat exchanger for evaporation and concentration after the gypsum eluent is treated by a purifying device; preferably, the dechlorination treatment mode is gypsum water washing or leaching dechlorination, and the gypsum eluent is purified and then conveyed to the forced circulation heat exchanger.
5. The separation and purification method according to claim 1, wherein the sodium chloride separation and purification apparatus in the step (4) is composed of a first thickener and a first centrifuge which are connected in sequence; wherein, the salt slurry enters a first thickener, and is purified and layered to obtain supernatant and sodium chloride crystal slurry; separating the sodium chloride crystal slurry by a first centrifugal machine to obtain sodium chloride crystal salt and sodium chloride mother liquor;
the sodium chloride separation and purification device in the step (4) consists of a supernatant tank, a crystallizing tank, a second thickener and a second centrifuge which are sequentially connected, wherein the supernatant enters the supernatant tank, enters the crystallizing tank when a potassium chloride solution is saturated, and is cooled to 10-50 ℃ in the crystallizing tank to separate out potassium chloride crystals; feeding the feed liquid in the crystallization tank into a second thickener to obtain potassium chloride crystal slurry and potassium chloride mother liquid, and separating the potassium chloride crystal slurry by a second centrifuge to obtain potassium chloride crystal salt and potassium chloride mother liquid;
preferably, the mother liquor stored in the mother liquor tank is treated by a mother liquor purification device and then conveyed to a forced circulation heat exchanger for continuous evaporation and concentration treatment.
6. A system for realizing the separation and purification method of any one of claims 1 to 5, which is characterized by comprising a multi-stage preheater (1), a first forced circulation heat exchanger (2), a gypsum seed tank (3), an evaporative crystallizer (4), a gypsum separator (5), a gypsum dehydration device (6), a sodium chloride separation and purification device (7) and a potassium chloride separation and purification device (8);
the multi-stage preheater (1) is provided with a fly ash washing liquid inlet, a preheated water inlet, a condensed water outlet and a discharge hole; the first forced circulation heat exchanger (2) is provided with a feed liquid inlet, a condensed water outlet and an evaporated liquid outlet; the gypsum seed crystal tank (3) is provided with a gypsum seed crystal inlet and a gypsum seed crystal outlet; the evaporation crystallizer (4) is provided with an evaporation liquid inlet, a gypsum seed crystal inlet, a crystal slurry outlet, a salt slurry outlet and a strong brine outlet; the gypsum separator (5) is provided with a crystal slurry inlet, a solid phase outlet and a mother liquid outlet; the gypsum dehydration device (6) is provided with a solid phase inlet, a water inlet, a gypsum outlet and a liquid phase outlet; the sodium chloride separation and purification device (7) is provided with a salt slurry inlet, a supernatant outlet, a sodium chloride crystal salt outlet and a sodium chloride mother liquor outlet; the potassium chloride separation and purification device (8) is provided with a supernatant inlet, a potassium chloride crystal outlet, a potassium chloride crystal salt outlet and a potassium chloride mother liquor outlet;
the discharge port of the multi-stage preheater (1) is connected with the feed liquid inlet of the first forced circulation heat exchanger (2), the evaporating liquid outlet of the first forced circulation heat exchanger (2) is connected with the evaporating liquid inlet of the evaporative crystallizer (4), and the gypsum seed crystal outlet of the gypsum seed crystal tank (3) is connected with the gypsum seed crystal inlet of the evaporative crystallizer (4); a crystal slurry outlet of the evaporation crystallizer (4) is connected with a crystal slurry inlet of the gypsum separator (5), and a solid phase outlet of the gypsum separator (5) is connected with a solid phase inlet of the gypsum dewatering device (6); the salt slurry outlet of the evaporation crystallizer (4) is connected with the salt slurry inlet of the sodium chloride separation and purification device (7), and the supernatant outlet of the sodium chloride separation and purification device (7) is connected with the supernatant inlet of the potassium chloride separation and purification device (8).
7. The system according to claim 6, characterized in that the preheated water inlet of the multistage preheater (1) is connected to the condensed water outlet of the first forced circulation heat exchanger (2); a strong brine outlet of the evaporation crystallizer (4) and a mother liquor outlet of the gypsum separator (5) are connected with a feed liquid inlet of the first forced circulation heat exchanger (2);
and a liquid phase outlet of the gypsum dewatering device (6) is connected with an inlet of the purification treatment device (9), and an outlet of the purification treatment device (9) is connected with a feed liquid inlet of the first forced circulation heat exchanger (2).
8. The system according to claim 6, characterized in that a sodium chloride mother liquor outlet of the sodium chloride separating and purifying device (7) and a potassium chloride mother liquor outlet of the potassium chloride separating and purifying device (8) are connected with a feed liquor inlet of the first forced circulation heat exchanger (2) through mother liquor return pipelines; preferably, a mother liquor return pipeline is sequentially connected with a mother liquor tank (16) and a mother liquor purification treatment device (17), wherein a sodium chloride mother liquor outlet of a sodium chloride separation and purification device (7) and a potassium chloride mother liquor outlet of a potassium chloride separation and purification device (8) are connected with an inlet of the mother liquor tank (16), an outlet of the mother liquor tank (16) is connected with an inlet of the mother liquor purification treatment device (17), and an outlet of the mother liquor purification treatment device (17) is connected with a feed liquor inlet of the first forced circulation heat exchanger (2) through the mother liquor return pipeline.
9. The system according to claim 6, wherein the sodium chloride separation and purification device (7) comprises a first thickener (10) and a first centrifuge (11) which are connected in sequence; wherein the first thickener (10) is provided with a feeding port, a supernatant outlet and a sodium chloride crystal slurry outlet; the first centrifugal machine (11) is provided with a sodium chloride crystal slurry inlet, a sodium chloride crystal salt outlet and a sodium chloride mother liquor outlet; a supernatant outlet of the first thickener (10) is connected with an inlet of a supernatant tank (12), a sodium chloride crystal slurry outlet of the first thickener (10) is connected with a sodium chloride crystal slurry inlet of a first centrifuge (11), and a sodium chloride mother liquor outlet of the first centrifuge (11) is connected with an inlet of a mother liquor tank (16);
the potassium chloride separation and purification device (8) comprises a supernatant liquid tank (12), a crystallizing tank (13), a second thickener (14) and a second centrifuge (15) which are connected in sequence; the upper clear liquid tank (12) is provided with a clear liquid inlet and a discharge port, the crystallizing tank is provided with a feed port, a potassium chloride crystal discharge port and a feed liquid outlet, the second thickener (14) is provided with a feed liquid inlet, a potassium chloride crystal slurry discharge port and a potassium chloride mother liquid discharge port, and the second centrifugal machine (15) is provided with a potassium chloride crystal slurry feed port, a potassium chloride crystal salt outlet and a potassium chloride mother liquid outlet; the discharge hole of the supernatant fluid tank (12) is connected with the feed inlet of the crystallizing tank, the feed fluid outlet of the crystallizing tank is connected with the feed fluid inlet of the second thickener (14), and the potassium chloride crystal slurry discharge hole of the second thickener (14) is connected with the potassium chloride crystal slurry feed inlet of the second centrifuge (15).
10. A system according to claim 9, characterized in that the potassium chloride mother liquor outlet of the second thickener (14) and the potassium chloride mother liquor outlet of the second centrifuge (15) are connected to the inlet of a mother liquor tank (16).
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| CN114715918A (en) * | 2022-03-23 | 2022-07-08 | 武汉宏达丰源分离技术有限公司 | Potassium salt evaporation separation process by gypsum crystal seed method |
| CN116984343A (en) * | 2023-09-25 | 2023-11-03 | 北京中科润宇环保科技股份有限公司 | System and process for recycling waste incineration fly ash |
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| CN114702045A (en) * | 2022-04-18 | 2022-07-05 | 中化(浙江)膜产业发展有限公司 | High-quality salt separation system and method for fly ash washing liquid |
| CN116984343A (en) * | 2023-09-25 | 2023-11-03 | 北京中科润宇环保科技股份有限公司 | System and process for recycling waste incineration fly ash |
| CN116984343B (en) * | 2023-09-25 | 2024-01-26 | 北京中科润宇环保科技股份有限公司 | System and process for recycling waste incineration fly ash |
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