CN113149059B - Method and system for crystallization separation of fly ash water washing liquid and separation and purification of sodium salt and potassium salt based on seed crystal method - Google Patents
Method and system for crystallization separation of fly ash water washing liquid and separation and purification of sodium salt and potassium salt based on seed crystal method Download PDFInfo
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- CN113149059B CN113149059B CN202110414612.5A CN202110414612A CN113149059B CN 113149059 B CN113149059 B CN 113149059B CN 202110414612 A CN202110414612 A CN 202110414612A CN 113149059 B CN113149059 B CN 113149059B
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- 239000013078 crystal Substances 0.000 title claims abstract description 156
- 239000007788 liquid Substances 0.000 title claims abstract description 147
- 238000000926 separation method Methods 0.000 title claims abstract description 92
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 87
- 238000000746 purification Methods 0.000 title claims abstract description 83
- 238000002425 crystallisation Methods 0.000 title claims abstract description 69
- 230000008025 crystallization Effects 0.000 title claims abstract description 68
- 238000005406 washing Methods 0.000 title claims abstract description 65
- 238000000034 method Methods 0.000 title claims abstract description 61
- 239000010881 fly ash Substances 0.000 title claims abstract description 58
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 title claims abstract description 22
- 159000000000 sodium salts Chemical class 0.000 title claims abstract description 16
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims abstract description 237
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 197
- 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 118
- 239000012452 mother liquor Substances 0.000 claims abstract description 114
- 238000001704 evaporation Methods 0.000 claims abstract description 107
- 239000011780 sodium chloride Substances 0.000 claims abstract description 97
- 230000008020 evaporation Effects 0.000 claims abstract description 93
- 239000002002 slurry Substances 0.000 claims abstract description 89
- 150000003839 salts Chemical class 0.000 claims abstract description 83
- 239000006228 supernatant Substances 0.000 claims abstract description 59
- 239000003480 eluent Substances 0.000 claims abstract description 15
- 238000006298 dechlorination reaction Methods 0.000 claims abstract description 11
- 239000000047 product Substances 0.000 claims abstract description 11
- 239000012266 salt solution Substances 0.000 claims abstract description 11
- 238000002386 leaching Methods 0.000 claims abstract description 6
- 239000002562 thickening agent Substances 0.000 claims description 45
- 239000007790 solid phase Substances 0.000 claims description 12
- 239000010413 mother solution Substances 0.000 claims description 9
- 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
- 239000007791 liquid phase Substances 0.000 claims description 6
- 239000000243 solution Substances 0.000 claims description 6
- 238000003860 storage Methods 0.000 claims description 5
- 229920006395 saturated elastomer Polymers 0.000 claims description 4
- 125000004122 cyclic group Chemical group 0.000 claims 2
- 239000012267 brine Substances 0.000 claims 1
- 238000007599 discharging Methods 0.000 claims 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 239000000126 substance Substances 0.000 description 8
- 238000004056 waste incineration Methods 0.000 description 8
- 208000005156 Dehydration Diseases 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 239000002956 ash Substances 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 239000011575 calcium Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000012958 reprocessing Methods 0.000 description 3
- 239000002351 wastewater 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
- 239000012527 feed solution Substances 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 239000002699 waste material 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
- 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
- 238000010828 elution Methods 0.000 description 1
- 239000011552 falling film Substances 0.000 description 1
- 238000001914 filtration Methods 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
- 230000000737 periodic effect Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
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
- 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
Abstract
The utility model discloses a crystallization separation method of fly ash washing liquid and a separation and purification method and system of sodium salt and potassium salt based on a seed crystal method, which comprises the following steps: preheating the fly ash washing liquid and then evaporating and concentrating the fly ash washing liquid; crystallizing and layering the concentrated feed liquid in an evaporation crystallizer to obtain crystal slurry, concentrated salt solution and salt slurry; separating the crystal slurry in a gypsum separator to obtain crystal gypsum and gypsum mother liquor; the salt slurry is treated in a sodium chloride separation and purification device to obtain sodium chloride crystal salt, supernatant and sodium chloride mother liquor; and processing 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 scaling of the evaporator, ensure the stable operation of the system and improve the quality of salt production; dechlorination treatment is carried out on the crystal gypsum by using a water washing or leaching mode, and gypsum products are recovered; the produced 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 utility model relates to a treatment method and a treatment system of waste incineration fly ash, in particular to a method and a system for separating and purifying sodium salt and potassium salt of fly ash by washing and crystallizing based on a seed crystal method, belonging to the field of reprocessing and utilization of waste incineration fly ash.
Background
The waste incineration fly ash contains a large amount of chloride ions, and is classified as solid hazardous waste (code HW 18) by China because the fly ash is rich in heavy metal inorganic harmful substances and high-concentration dioxin organic carcinogens. The technology of using cement kiln to cooperatively treat waste incineration fly ash is a new treatment means in the development of fly ash treatment technology, and the main process is that the waste incineration fly ash is washed by water, the rest fly ash after washing is dried to prepare cement, and the waste water produced by washing is collected and treated to meet the requirement of evaporating and crystallizing water quality, and then the waste water is treated by evaporating and salifying process.
The water washing pretreatment can transfer soluble substances (potassium, sodium and chloride ions) in the fly ash into the water washing liquid. The fly ash washing liquid contains about 6-15 wt% of potassium and sodium salt, while Chinese potassium salt resources are relatively scarce, and potassium salt and sodium salt are prepared from the fly ash washing liquid by an evaporation crystallization technology, so that the potassium salt vacancy in China is relieved. In the evaporating crystallization process, firstly, sodium salt with high content is crystallized and separated, then mother liquor is continuously refluxed to enrich potassium salt, and the potassium salt can be separated out after reaching saturation, and the mixed salt of sodium salt and potassium salt is obtained.
Chinese patent (CN 108191135A) discloses a system and 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 isocratic cooling crystallization unit; each unit is internally provided with an independent condensed water collecting system, a non-condensable gas treatment system and a mechanical vapor recompression system; the forced circulation crystallization unit is provided with separation equipment, and potassium salt and sodium salt are used for separation. The utility model provides an important way for preparing salt by evaporating the waste incineration fly ash or kiln ash water washing liquid, has simple and convenient operation, improves the treatment effect and prolongs the service life of equipment, and is beneficial to the recycling utilization of beneficial components wrapped in the waste incineration fly ash or kiln ash water washing pretreatment product and the water washing liquid.
Aiming at the evaporation salt production process of the fly ash or kiln ash water washing liquid with high salt content, although the prior art realizes the advantages of difficult incrustation of equipment, good salt quality of products and stable system operation to a certain extent, the components of the fly ash water washing liquid are complex, the salt concentration is high, the feed liquid is continuously and circularly evaporated in the evaporation process, salt grain crystals in the concentrated feed liquid can be attached to the surface of an evaporator, so that uneven heat transfer and low heat transfer efficiency are caused, energy waste is caused, and the periodic shutdown cleaning is needed, so that the production efficiency is seriously influenced.
Disclosure of Invention
The utility model aims to provide a fly ash water-washing crystallization separation and sodium salt and potassium salt separation and purification method based on a seed crystal method;
the utility model aims to provide a treatment system for realizing the fly ash water-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 utility model is achieved by the following technical solutions:
the utility model firstly provides a crystallization separation and purification method of fly ash water washing liquid and sodium salt and potassium salt based on a seed crystal method, which comprises the following steps: (1) Preheating fly ash washing liquid in a preheater to obtain preheated fly ash 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, concentrated salt solution and salt slurry; (4) Carrying out separation treatment on gypsum and feed liquid on the crystal slurry in a gypsum separator to obtain crystal gypsum and gypsum mother liquor; purifying and separating crystalline sodium chloride salt and feed liquid in a sodium chloride separation and purification device to obtain crystalline sodium chloride salt, supernatant and sodium chloride mother liquor; separating and purifying the supernatant in a potassium chloride separating and purifying device to obtain potassium chloride crystals, potassium chloride crystal salt and potassium chloride mother liquor; (5) Conveying the concentrated salt solution obtained in the step (3) and the gypsum mother solution and the sodium chloride mother solution obtained in the step (4) into a forced circulation heat exchanger for evaporation concentration treatment, and repeating the treatment steps (3) - (4); and (3) conveying the sodium chloride mother liquor obtained in the step (4) and the potassium chloride mother liquor to a mother liquor tank for storage.
In the step (1), the purified fly ash water washing liquid is subjected to preheating treatment by a multi-stage preheater to obtain the preheated water washing liquid with the temperature of 90-110 ℃, and condensed water generated in the preheater is used as water for eluting a gypsum dewatering device.
As a preferred embodiment of the present utility model, the condensate water produced by the forced circulation heat exchanger in step (2) is supplied to the preheating water of the preheater of step (1), wherein the condensate water temperature is 80-100 ℃.
As a preferred embodiment of the utility model, in the step (2), when the preheated fly ash water washing liquid is subjected to evaporation concentration treatment in the forced circulation heat exchanger, the temperature of the forced circulation heat exchanger is controlled to be 100-120 ℃.
As a preferred embodiment of the utility model, in the step (3), gypsum seed crystals, preferably 15-30g/L gypsum seed crystals, are added when the concentrated feed solution is fed into an evaporation crystallizer for evaporation crystallization. By utilizing the principle that the affinity of the same kind of substance is greater than that of different kinds of substance, the small solid gypsum particles are uniformly dispersed in the feed liquid in the evaporating crystallizer, and Ca in the feed liquid 2+ And SO 4 2- Will first agglomerate on the solid gypsum nucleus to form crystallization.
As a preferred embodiment of the utility model, the concentrated salt solution obtained in the step (3) is subjected to two times of evaporation concentration treatment and then returned to an evaporation crystallizer for crystallization and layering treatment, and the cycle is repeatedly performed for multiple times of cycle evaporation concentration and evaporation crystallization treatment.
In the step (3), the crystallized gypsum is subjected to dechlorination treatment to obtain a gypsum product and a gypsum eluent, and the gypsum eluent is treated by a purification device and then is conveyed to a forced circulation heat exchanger for evaporation concentration treatment; preferably, the dechlorination treatment mode is a gypsum water washing or leaching mode for dechlorination, and the gypsum eluent is conveyed to the forced circulation heat exchanger after being purified.
As a preferred embodiment of the present utility model, the sodium chloride separating and purifying apparatus in step (4) is composed of a first thickener and a first centrifuge connected in sequence; wherein, the salt slurry enters a first thickener for purification and layering treatment to obtain supernatant and sodium chloride crystal slurry; and separating the sodium chloride crystal slurry by a first centrifugal machine to obtain sodium chloride crystal salt and sodium chloride mother liquor.
As a preferred embodiment of the utility model, the potassium chloride separating and purifying device in the step (4) consists 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, and enters the crystallization tank after the potassium chloride solution is saturated, and potassium chloride crystals are separated out when the temperature in the crystallization tank is reduced to 10-50 ℃; 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 a second centrifugal machine to obtain potassium chloride crystal salt and potassium chloride mother liquor.
As a preferred embodiment of the utility model, the mother solution stored in the mother solution tank is treated by the mother solution purifying device and then is conveyed to the forced circulation heat exchanger for continuous evaporation and concentration treatment.
The above-described methods can be accomplished by one skilled in the art using various conventional equipment for fly ash treatment and reuse, all of which are readily accomplished by one skilled in the art.
As a preferred embodiment, the utility model 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 multistage 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 water 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 tank is provided with a gypsum seed inlet and a gypsum seed 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 concentrated salt liquid outlet; the gypsum separator is provided with a crystal slurry inlet, a solid phase outlet and a mother liquor 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 crystal 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;
wherein, the discharge port of the multistage preheater is connected with the feed liquid inlet of the first forced circulation heat exchanger, the evaporation liquid outlet of the first forced circulation heat exchanger is connected with the evaporation liquid inlet of the evaporation crystallizer, and the gypsum seed crystal outlet of the gypsum seed crystal tank is connected with the gypsum seed crystal inlet of the evaporation 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 dehydration 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 utility model, the preheating water inlet of the multistage preheater is connected with the condensate water outlet of the first forced circulation heat exchanger; the concentrated salt liquid outlet of the evaporation crystallizer and the mother liquid outlet of the gypsum separator are connected with the liquid inlet of the first forced circulation heat exchanger.
As a preferred embodiment of the utility model, the liquid phase outlet of the gypsum dewatering device is connected with the inlet of the purifying device, and the outlet of the purifying device is connected with the feed liquid inlet of the first forced circulation heat exchanger.
As a preferred embodiment of the utility model, 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 a feed liquor inlet of the first forced circulation heat exchanger through a mother liquor return pipeline; further preferably, the liquid reflux pipeline is sequentially connected with a mother liquid tank and a mother liquid purification treatment device, wherein a sodium chloride mother liquid outlet of the sodium chloride separation and purification device and a potassium chloride mother liquid outlet of the potassium chloride separation and purification device are connected with an inlet of the mother liquid tank, an outlet of the mother liquid tank is connected with an inlet of the mother liquid purification treatment device, and an outlet of the mother liquid purification treatment device is connected with a feed liquid inlet of the forced circulation heat exchanger through the mother liquid reflux pipeline.
As a preferred specific embodiment of the utility model, the sodium chloride separation and purification device comprises a first thickener and a first centrifuge which are connected in sequence; wherein the first thickener is provided with a feed inlet, 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 tank, a crystallization tank, a second thickener and a second centrifuge which are connected in sequence; the second thickener is provided with a feed liquid inlet, a potassium chloride crystal slurry outlet and a potassium chloride mother liquor 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 liquor outlet; the discharge port of the supernatant tank is connected with the feed port of the crystallization tank, the feed liquid outlet of the crystallization tank is connected with the feed liquid inlet of the second thickener, and the potassium chloride crystal slurry discharge port of the second thickener is connected with the potassium chloride crystal slurry feed port of the second centrifuge.
As a preferred embodiment of the utility model, the potassium chloride mother liquor discharge port of the second thickener and the potassium chloride mother liquor outlet of the second centrifuge are connected with the inlet of the mother liquor tank.
The utility model effectively utilizes the gypsum seed crystal method in the evaporation crystallization process of the fly ash washing liquid, and solves the problems of easy scaling of equipment in the evaporation crystallization process, low yield of crystal salt and poor quality. The water washing liquid evaporation salt making process based on the gypsum seed crystal method can effectively prevent the scaling of an evaporator, reduce the heat transfer energy consumption of mass transfer and ensure the stable operation of the system; sulfate radical and calcium ions in the water washing liquid are adhered to the gypsum seed crystal to form crystalline gypsum, so that the content of sulfate radical in the crystalline salt is effectively reduced, and the quality of salt production is further improved; the utility model carries out water washing treatment on the spar paste, removes soluble impurities in gypsum, improves the added value of gypsum products, returns gypsum eluent and mother liquor generated in the crystallization separation process to a forced circulation heat exchange device for continuous concentration and evaporation, and realizes zero discharge of wastewater in the process; in addition, the evaporation concentration process adopts a forced circulation heat exchanger, so that the scaling phenomenon of equipment in the evaporation concentration process is reduced.
Compared with the prior art, the utility model has the following advantages and outstanding 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 scaling of an evaporator and ensure the stable operation of the system; solves the technical problem that sulfate radical affects the quality of crystallized salt, and can improve the quality of the product salt.
2. The method has the advantages that the crystal gypsum is subjected to dechlorination treatment by using a water washing or leaching mode, gypsum products can be recovered, the product value is improved, and the economic benefit is good.
3. And condensed water and 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 method of the present utility model.
FIG. 2 is a process flow diagram of another embodiment of the method of the present utility model.
FIG. 3 is a schematic diagram of the components and connections of the devices in an embodiment of the present utility model.
FIG. 4 is another schematic diagram of the components and connection relationships of devices in another embodiment of the present utility model.
FIG. 5 is a schematic diagram of the connection between the evaporative crystallizer and the first forced circulation heat exchanger and the second forced circulation heat exchanger.
Reference numerals: 1-multistage preheater, 2-first forced circulation heat exchanger, 3-gypsum seed tank, 4-evaporation crystallizer, 5-gypsum separator, 6-gypsum dewatering device, 7-sodium chloride separation purification device, 8-potassium chloride separation purification device, 9-purification treatment device, 10-first thickener, 11-first centrifuge, 12-supernatant fluid tank, 13-crystallization tank, 14-second thickener, 15-second centrifuge, 16-mother liquor tank, 17-mother liquor purification treatment device, 18-second forced circulation heat exchanger.
Detailed Description
The utility model will be further described with reference to specific embodiments, and advantages and features of the utility model will become apparent from the description. It should be understood that the embodiments described are exemplary only and should not be construed as limiting the scope of the utility model in any way. It will be understood by those skilled in the art that various changes and substitutions can be made in the details and form of the technical solution of the present utility model without departing from the spirit and scope of the utility model, but these changes and substitutions fall within the scope of the present utility model.
In the description of the embodiments of the present utility model, it should be noted that, the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship conventionally put in use of the product of the application as understood by those skilled in the art, which is merely for convenience of describing the present utility model and simplifying the description, and is not indicative or implying that the apparatus or element to be referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present utility model. In the description of the embodiments of the present utility model, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; may be directly connected or indirectly connected through an intermediate medium. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.
In the description of embodiments of the present utility model, a description of reference to the terms "one embodiment," "some embodiments," "examples," "particular examples," 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 utility model. In this specification, schematic representations of the above terms are not necessarily directed 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, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Referring to fig. 1, the present utility model firstly provides a crystallization separation and purification method of a fly ash water washing liquid and sodium salt and potassium salt based on a seed crystal method, comprising: (1) Preheating fly ash washing liquid in a preheater to obtain preheated fly ash 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, concentrated salt solution and salt slurry; (4) Carrying out separation treatment on gypsum and feed liquid on the crystal slurry in a gypsum separator to obtain crystal gypsum and gypsum mother liquor; purifying and separating crystalline sodium chloride salt and feed liquid in a sodium chloride separation and purification device to obtain crystalline sodium chloride salt, supernatant and sodium chloride mother liquor; separating and purifying the supernatant in a potassium chloride separating and purifying device to obtain potassium chloride crystals, potassium chloride crystal salt and potassium chloride mother liquor; (5) Conveying the concentrated salt solution obtained in the step (3) and the gypsum mother solution and the sodium chloride mother solution obtained in the step (4) into a forced circulation heat exchanger for evaporation concentration treatment, and repeating the treatment steps (3) - (4); and (3) conveying the sodium chloride mother liquor obtained in the step (4) and the potassium chloride mother liquor to a mother liquor tank for storage.
As a preferred embodiment of the utility model, the purified fly ash water washing liquid in the step (1) is subjected to preheating treatment by a multi-stage preheater to obtain a preheated water washing liquid at the temperature of 90-110 ℃, condensed water generated in the preheater is used as water for eluting a gypsum dewatering device, and 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 utility model, in the step (2), when the preheated fly ash water washing liquid is subjected to evaporation concentration treatment in the forced circulation heat exchanger, the temperature of the forced circulation heat exchanger is controlled to be 100-120 ℃.
As a preferred embodiment of the utility model, in the step (3), gypsum seed crystals, preferably 15-30g/L gypsum seed crystals, are added when the concentrated feed solution is fed into an evaporation crystallizer for evaporation crystallization. By utilizing the principle that the affinity of the same kind of substance is greater than that of different kinds of substance, the small solid gypsum particles are uniformly dispersed in the feed liquid in the evaporating crystallizer, and Ca in the feed liquid 2+ And SO 4 2- Will first agglomerate on the solid gypsum nucleus to form crystallization.
Referring to fig. 2 and 5, in a specific embodiment of the present utility model, the concentrated salt solution obtained in the step (3) is sequentially subjected to evaporation concentration treatment twice in the second forced circulator 18 and the first forced circulator 2, and then returned to the evaporation crystallizer 4 for crystallization and layering treatment, so that multiple circulation evaporation concentration and evaporation crystallization treatment are performed repeatedly.
As a more preferable specific embodiment of the utility model, in the step (3), the crystallized gypsum is subjected to dechlorination treatment to obtain a gypsum product and a gypsum eluent, and the gypsum eluent is treated by a purification device and then is conveyed to the first forced circulation heat exchanger 2 or the second forced circulation device 18 for evaporation concentration treatment; preferably, the dechlorination treatment mode is a gypsum water washing or leaching mode for dechlorination, and the gypsum eluent is conveyed to the forced circulation heat exchanger after being purified.
Referring to fig. 4, in one embodiment of the present utility model, the sodium chloride separation and purification apparatus 7 described in step (4) is composed of a first thickener 10 and a first centrifuge 11 connected in this order; wherein, the salt slurry enters a first thickener 11 for purification and layering treatment to obtain supernatant and sodium chloride crystal slurry; and separating the sodium chloride crystal slurry by a first centrifugal machine 11 to obtain sodium chloride crystal salt and sodium chloride mother liquor.
Referring to fig. 4, the potassium chloride separation and purification device 8 in the step (4) is composed of a supernatant tank 12, a crystallization tank 13, a second thickener 14 and a second centrifuge 15 which are sequentially connected, wherein the supernatant enters the supernatant tank 12, and after the potassium chloride solution is saturated, the supernatant enters the crystallization tank 13, and potassium chloride crystals are precipitated when the temperature in the crystallization tank 13 is reduced to 10-50 ℃; 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 centrifuge 15 to obtain potassium chloride crystal salt and potassium chloride mother liquor.
As a specific embodiment of the present utility model, the mother liquor stored in the mother liquor tank 16 is treated by the mother liquor purifying device 17 and then is sent to the first forced circulation heat exchanger 2 for further evaporation and concentration treatment.
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 comprises a multistage 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 dewatering device 6, a sodium chloride separation and purification device 7 and a potassium chloride separation and purification device 8; the multistage preheater 1 is provided with a fly ash water 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 tank 3 is provided with a gypsum seed inlet and a gypsum seed 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 concentrated salt liquid outlet; the gypsum separator 5 is provided with a crystal slurry inlet, a solid phase outlet and a mother liquor 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 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;
wherein, the discharge port of the multistage 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 evaporation 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 evaporation crystallizer 4; the crystal slurry outlet of the evaporation crystallizer 4 is connected with the crystal slurry inlet of the gypsum separator 5, and the solid phase outlet of the gypsum separator 5 is connected with the 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.
In a preferred embodiment, the preheating water inlet of the multistage preheater 1 is connected with the condensate water outlet of the first forced circulation heat exchanger 2; the concentrated salt liquid outlet of the evaporation crystallizer 4 and the mother liquid outlet of the gypsum separator 5 are connected with the 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 purifying device 9, and the outlet of the purifying 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 utility model, 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 to a feed liquor inlet of the first forced circulation heat exchanger 2 through a mother liquor return line; further preferably, a mother liquor tank 16 and a mother liquor purifying device 17 are sequentially connected to a mother liquor return line, 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 to an inlet of the mother liquor tank 16, an outlet of the mother liquor tank 16 is connected to an inlet of the mother liquor purifying device 17, and an outlet of the mother liquor purifying device 17 is connected to a feed liquor inlet of the first forced circulation heat exchanger 2 through the mother liquor return line.
Referring to fig. 4, in one embodiment of the present utility model, the sodium chloride separation and purification device 7 includes a first thickener 10 and a first centrifuge 11 connected in sequence; wherein, the first thickener 10 is provided with a feed inlet, 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; the supernatant outlet of the first thickener 10 is connected with the inlet of the supernatant tank 12, the sodium chloride crystal slurry outlet of the first thickener 10 is connected with the sodium chloride crystal slurry inlet of the first centrifuge 11, and the sodium chloride mother liquor outlet of the first centrifuge 11 is connected with the inlet of the 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 hole, the crystallization tank is provided with a feed hole, a potassium chloride crystal discharge hole and a feed liquid outlet, the second thickener 14 is provided with a feed liquid inlet, a potassium chloride crystal slurry discharge hole and a potassium chloride mother liquid discharge hole, and the second centrifuge 15 is provided with a potassium chloride crystal slurry feed hole, 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 crystallization tank, the feed liquid outlet of the crystallization tank is connected with the feed liquid inlet of the second thickener 14, and the discharge port of the potassium chloride crystal slurry of the second thickener 14 is connected with the feed port of the potassium chloride crystal slurry of the second centrifuge 15.
The potassium chloride mother liquor discharge port of the second thickener 14 and the potassium chloride mother liquor outlet of the second centrifuge 15 are connected with the inlet of the mother liquor tank.
The various devices or apparatuses used in the utility model are conventional devices in solid waste reprocessing or waste fly ash reprocessing technologies, which can be purchased commercially and can be applied to the utility model; in addition, the related literature also discloses new improved devices, and better technical effects can be achieved by adopting the new improved devices, such as: multistage elution separation device (CN 204848668U, title of the utility model: fly ash washing device); multistage filtration device (CN 205627217U, title of the utility model: quick-open type multimedia filter).
The method and system of the present utility model are further described below in conjunction with specific embodiments.
Example 1 fly ash water-washing crystallization separation system based on seed crystal method and separation and purification of potassium salt
Referring to fig. 1 and 3, the present embodiment provides a fly ash water-washing crystallization separation system based on a seed crystal method and a separation and purification method of potassium salt, comprising:
preheating the water washing liquid in the step (1): the fly ash washing liquid after the purification treatment is preheated in a multistage preheater 1 to obtain preheated feed liquid at the temperature of 90-110 ℃, and condensed water generated in the multistage preheating process is used as dechlorination water of a gypsum dehydration device.
And (3) evaporating and concentrating: pumping the preheated feed liquid into a forced circulation heat exchanger 2 through a feed pipe, evaporating and concentrating the preheated feed liquid in the forced circulation heat exchanger 2 to obtain concentrated feed liquid, wherein the temperature of the heat exchanger is controlled to be 100-120 ℃, the solid-liquid ratio of the feed liquid is more than or equal to 30%, condensed water generated in the forced circulation heat exchange process in the step (2) is supplied to a multistage preheater for preheating, and the temperature of the condensed water is 80-100 ℃;
and (3) crystallizing by a seed crystal method: and (3) delivering 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 liquid and salt slurry with the salt content of 30-60 wt%. Wherein 15-30g/L gypsum seed crystal is added into the evaporation crystallizer, and the principle that the affinity of the same substance is larger than that of different substances is utilized, the small solid gypsum particles are uniformly dispersed in the feed liquid in the evaporation crystallizer, and Ca in the feed liquid 2+ And SO 4 2- Will first condense on the solid gypsum nucleus to form gypsum crystal precipitation.
The concentrated salt solution is conveyed to the forced circulation heat exchanger 2 to be continuously evaporated and concentrated;
and (4) gypsum separation: the crystal slurry in the evaporation crystallizer 2 enters a gypsum separator 5, gypsum and feed liquid are separated, so that crystalline gypsum with the water content not more than 60wt% is obtained, and the separated feed liquid is conveyed to a forced circulation heat exchanger 2 for continuous evaporation concentration treatment; the crystallized gypsum is sent to a gypsum dehydration device 6 for treatment, preferably gypsum washing or leaching, so as to obtain gypsum and gypsum eluent, and the gypsum eluent is sent to a 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 crystalline salt and the feed liquid are purified and separated to obtain sodium chloride crystalline salt with the water content of not more than 6wt%, supernatant fluid and sodium chloride mother liquor;
step (6) of potassium chloride crystallization separation, namely sending the supernatant in the step (5) into a potassium chloride crystallization 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 6wt% and potassium chloride mother liquor;
the sodium chloride mother liquor generated in the step (5) and the potassium chloride mother liquor generated in the step (6) are conveyed to the first forced circulation heat exchanger 2 for continuous evaporation concentration treatment.
Example 2 fly ash water-washing crystallization separation system based on seed crystal method and separation and purification of potassium salt
Referring to fig. 2 and 4, the steps are as follows:
a. the purified fly ash water washing liquid enters a multistage preheater 1 for preheating.
b. The preheated feed liquid is evaporated and concentrated 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 liquid and salt slurry with the salt content of 30-60 wt%.
d. Adding 15-30g/L gypsum seed crystal into the evaporation crystallizer,
e. the crystal slurry enters a gypsum separator 5 for separation treatment to obtain crystal gypsum with the water content not more than 60 weight percent and gypsum mother liquor; and carrying out gypsum dehydration treatment on the crystallized gypsum, and conveying gypsum eluent to the first forced circulation heat exchanger 2 after treatment by the purification treatment device 9 to continue evaporation concentration treatment.
f. Sodium chloride separation: the salt slurry in the evaporation crystallizer 4 enters a first thickener 10, and is purified and layered to obtain supernatant and sodium chloride crystal slurry; and separating the sodium chloride crystal slurry by a first centrifugal machine 11 to obtain sodium chloride crystal salt and sodium chloride mother liquor. The sodium chloride mother liquor is transferred to a mother liquor tank 16 for storage.
g. Potassium chloride separation: the supernatant separated in the first thickener 10 enters a supernatant tank 12, the potassium chloride solution in the supernatant tank 12 is saturated and then enters a crystallization tank 13, and potassium chloride crystals are separated out when the temperature in the crystallization tank 13 is reduced to 10-50 ℃; the feed liquid in the crystallization 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; the potassium chloride mother liquor separated by the second thickener 14 and the second centrifuge 15 is conveyed to a mother liquor tank 16 for storage; the mother liquor stored in the mother liquor tank 16 is processed by the mother liquor purifying device 17 and then is conveyed to the first forced circulation heat exchanger 2 for further evaporation and concentration.
Example 3 fly ash Water washing crystallization separation System based on seed crystal method and separation and purification of potassium salt
Referring to fig. 5, the difference from embodiment 2 is that: the concentrated salt solution obtained by the evaporation crystallizer 4 sequentially passes through the second forced circulation heat exchanger 18 and the first forced circulation heat exchanger 2, is evaporated and concentrated twice, and then returns to the evaporation crystallizer 4 again for multiple forced circulation evaporation and concentration treatment.
Claims (9)
1. A crystallization separation and purification method of fly ash water washing liquid and sodium salt and potassium salt based on a seed crystal method comprises the following steps: (1) Preheating fly ash washing liquid in a preheater to obtain preheated fly ash 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, concentrated salt solution and salt slurry; (4) Carrying out separation treatment on gypsum and feed liquid on the crystal slurry 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 separating and purifying device to obtain potassium chloride crystals, potassium chloride crystal salt and potassium chloride mother liquor; (5) Conveying the concentrated salt solution obtained in the step (3) and the gypsum mother solution and the sodium chloride mother solution obtained in the step (4) into a forced circulation heat exchanger for evaporation concentration treatment, and repeating the treatment steps (3) - (4); conveying the sodium chloride mother liquor obtained in the step (4) and the potassium chloride mother liquor into a mother liquor tank for storage;
in the step (3), the concentrated feed liquid is sent into an evaporation crystallizer for evaporation crystallization, 15-30g/L gypsum seed crystal is added for crystallization, so that Ca in the feed liquid 2+ And SO 4 2- Will first coagulate on the solid gypsum crystal nucleus to form crystallization,
in the step (3), the crystallized gypsum is dechlorinated to obtain gypsum products and gypsum eluent, the gypsum eluent is sent to a forced circulation heat exchanger for evaporation concentration treatment after being treated by a purifying device,
the sodium chloride separation and purification device in the step (4) consists of a first thickener and a first centrifuge which are connected in sequence; wherein, the salt slurry enters a first thickener for purification and layering treatment 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 potassium chloride separation and purification device in the step (4) consists 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, and enters the crystallization tank after the potassium chloride solution is saturated, and potassium chloride crystals are separated out when the temperature in the crystallization tank is reduced to 10-50 ℃; 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 a second centrifugal machine to obtain potassium chloride crystal salt and potassium chloride mother liquor.
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 water for eluting 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 ℃; in the step (2), when the preheated fly ash water washing liquid is subjected to evaporation concentration treatment in the forced circulation heat exchanger, the temperature of the forced circulation heat exchanger is controlled to be 100-120 ℃.
3. The separation and purification method according to claim 1, wherein the concentrated brine obtained in the step (3) is subjected to two times of evaporation and concentration treatment and then returned to the evaporation crystallizer for crystallization and layering treatment, and the cyclic reciprocation is used for multiple times of cyclic evaporation and concentration and evaporation and crystallization treatment;
the dechlorination treatment mode is a gypsum water washing or leaching mode for dechlorination, and the gypsum eluent is conveyed to the forced circulation heat exchanger after being purified.
4. The separation and purification method according to claim 1, wherein in the step (4), the mother liquor stored in the mother liquor tank is treated by the mother liquor purifying apparatus and then transferred to the forced circulation heat exchanger for further evaporation and concentration.
5. A system for implementing the separation and purification method according to any one of claims 1 to 4, characterized by comprising a multistage preheater (1), a first forced circulation heat exchanger (2), a gypsum seed tank (3), an evaporative crystallizer (4), a gypsum separator (5), a gypsum dewatering device (6), a sodium chloride separation and purification device (7) and a potassium chloride separation and purification device (8);
the multistage preheater (1) is provided with a fly ash washing liquid inlet, a preheating 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 tank (3) is provided with a gypsum seed inlet and a gypsum seed 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 concentrated salt liquid outlet; the gypsum separator (5) is provided with a crystal slurry inlet, a solid phase outlet and a mother liquor 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 discharging port of the multistage 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 evaporation 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 evaporation crystallizer (4); the crystal slurry outlet of the evaporation crystallizer (4) is connected with the crystal slurry inlet of the gypsum separator (5), and the solid phase outlet of the gypsum separator (5) is connected with the 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); the preheating water inlet of the multistage preheater (1) is connected with the condensate water outlet of the first forced circulation heat exchanger (2); the concentrated salt liquid outlet of the evaporation crystallizer (4) and the mother liquid outlet of the gypsum separator (5) are connected with the liquid inlet of the first forced circulation heat exchanger (2);
the liquid phase outlet of the gypsum dehydration 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).
6. The system according to claim 5, characterized in that 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 with the feed liquor inlet of the first forced circulation heat exchanger (2) through a mother liquor return line.
7. The system according to claim 6, characterized in that a mother liquor tank (16) and a mother liquor purifying device (17) are connected in sequence in a mother liquor return line, wherein 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 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 purifying device (17), and an outlet of the mother liquor purifying device (17) is connected with a feed liquor inlet of the first forced circulation heat exchanger (2) through the mother liquor return line.
8. The system according to claim 5, 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 feed inlet, 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; the supernatant outlet of the first thickener (10) is connected with the inlet of the supernatant tank (12), the sodium chloride crystal slurry outlet of the first thickener (10) is connected with the sodium chloride crystal slurry inlet of the first centrifuge (11), and the sodium chloride mother liquor outlet of the first centrifuge (11) is connected with the inlet of the mother liquor tank (16);
the potassium chloride 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 hole, the crystallization tank is provided with a feed inlet, a potassium chloride crystal discharge hole and a feed liquid outlet, the second thickener (14) is provided with a feed liquid inlet, a potassium chloride crystal slurry discharge hole and a potassium chloride mother liquid discharge hole, and the second centrifuge (15) is provided with a potassium chloride crystal slurry feed hole, 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 arranged on the crystallization tank, the feed liquid outlet of the crystallization tank 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 port of the second centrifuge (15).
9. The system according to claim 8, 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 the mother liquor tank (16).
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| CN113772708A (en) * | 2021-09-23 | 2021-12-10 | 华新绿源环保股份有限公司 | Comprehensive recycling treatment process for complex waste salt system |
| 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 |
| 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 |
| 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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| CN105016555A (en) * | 2015-07-18 | 2015-11-04 | 北京建筑材料科学研究总院有限公司 | Garbage fly ash water washing liquid evaporation desalination system and method |
| CN108191135A (en) * | 2018-01-31 | 2018-06-22 | 北京中科国润环保科技有限公司 | A kind of incineration of refuse flyash or kiln ash water lotion evaporation salt making system and method |
| CN109095531A (en) * | 2018-09-12 | 2018-12-28 | 深圳市瑞升华科技股份有限公司 | Garbage flying ash wash water recycling treatment process and equipment |
| CN110183025A (en) * | 2019-06-28 | 2019-08-30 | 中国科学院理化技术研究所 | Desulfurization wastewater recycling processing method and system |
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