CN116253335A - Salt separation process of quaternary water salt system - Google Patents
Salt separation process of quaternary water salt system Download PDFInfo
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- CN116253335A CN116253335A CN202310351273.XA CN202310351273A CN116253335A CN 116253335 A CN116253335 A CN 116253335A CN 202310351273 A CN202310351273 A CN 202310351273A CN 116253335 A CN116253335 A CN 116253335A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
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- 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
- C01D3/06—Preparation by working up brines; seawater or spent lyes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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Abstract
The invention discloses a quaternary water salt system salt separation process, which comprises the following steps: the salt separation process comprises the following steps: s1: preparing raw materials, wherein the water quality of the raw materials contains K + 、Na + 、Cl ‑ 、SO 4 2‑ The method comprises the steps of carrying out a first treatment on the surface of the S2: the raw materials enter a freezing and crystallizing system through a plate-type precooler, and the freezing and crystallizing system can lead SO to be discharged 4 2‑ Separating out sodium sulfate decahydrate, and separating out the sodium sulfate decahydrate from the raw materials through a freezing crystallization system; the invention adopts freezing crystallization, evaporating crystallization, vacuum flash crystallization and cooling crystallization technology to fully separate the salt components in the raw material liquid; proper treatment methods are selected and combined to realize recycling of high-salt wastewater, so that high-purity industrial salt is produced; separating sodium sulfate decahydrate by adopting a freezing crystallization system, preparing a sodium chloride product by adopting an evaporation crystallization system, and producing potassium chloride by adopting a cooling crystallization system; realizing the salt separation of three salts in a quaternary water salt systemPurifying to obtain the industrial salt product with high purity.
Description
Technical Field
The invention relates to the technical field of salt separation, in particular to a quaternary water salt system salt separation process.
Background
The salt separation process mainly adopts an evaporation crystallization salt separation process and a nanofiltration salt separation process. The evaporation crystallization salt separation process is realized by utilizing the difference of solubility of NaCl and different temperatures, and the principle is that sodium sulfate is obtained under the high-temperature condition and sodium chloride is obtained under the low-temperature condition, so that mixed salt and industrial salt can be generated together in the process of separating salt from raw material liquid in the nanofiltration salt separation process, and industrial salt and mixed salt can be formed. Therefore, it is necessary to improve the purity of industrial salt in the salt separation of the raw material liquid system, and to separate industrial salt from mixed salt.
In the related technology, nanofiltration and salt separation are carried out by using nanofiltration membranes, the nanofiltration membrane is a novel separation membrane, the aperture of the nanofiltration membrane is generally 1-2 nm, the molecular weight cut-off is between the reverse osmosis membrane and the ultrafiltration membrane, and the nanofiltration membrane has a certain cut-off rate on inorganic salt, so that the inorganic salt is formed.
However, in the process of separating salt from a raw material liquid system, the reverse osmosis membrane and the ultrafiltration membrane have a certain rejection rate on inorganic salt after the salt from the raw material liquid system is separated, so that the inorganic salt in the reverse osmosis membrane and the ultrafiltration membrane is extracted, and further, in the extraction process, the generation of mixed salt can occur, so that the purity of industrial salt is reduced.
Disclosure of Invention
The invention aims to provide a quaternary water-salt system salt separation process for solving the problems in the background technology.
In order to achieve the above purpose, the present invention provides the following technical solutions: a quaternary water salt system salt separation process, comprising: the salt separation process comprises the following steps:
s1: preparing raw materials, wherein the water quality of the raw materials contains K + 、Na + 、Cl - 、SO 4 2- ；
S2: the raw material enters a freezing and crystallizing system through a plate-type precooler, and the freezing and crystallizing system lets SO 4 2- Separating out sodium sulfate decahydrate in the form of sodium sulfate decahydrate, and allowing the raw materials to pass through a freezing crystallization system to separate out the sodium sulfate decahydrate;
s3: the clear liquid of the freezing crystallization system enters an evaporation crystallization system through a plate-type precooler, a salt mixing buffer tank and a condensate water preheater to generate sodium chloride products;
s4: condensed water in the evaporative crystallization system can flow back into the condensed water preheater, and the condensed water preheater discharges the condensed water outwards;
s5: feeding the clear liquid discharged from the evaporation crystallization system into a vacuum flash crystallization system, cooling to separate out mixed salt, returning the mixed salt to the evaporation crystallization system after the mixed salt is dissolved back, and continuing to evaporate and concentrate to produce sodium chloride products;
the main component of the impurity salt is sodium chloride;
s6: the evaporation crystallization system flows downwards, so that the potassium chloride enters the vacuum flash crystallization system, and clear liquid of the vacuum flash crystallization system enters the cooling crystallization system to separate out potassium chloride products;
s7: and returning the clear liquid of the cooling crystallization system to the raw material buffer tank.
The freezing end temperature of the freezing crystallization system is 0 ℃.
The discharge efficiency temperature of the evaporative crystallization system is set to be 100 ℃.
And the clear liquid discharged by the evaporation crystallization system enters a vacuum flash crystallization system for cooling, and the temperature of the vacuum flash crystallization system is 50-55 ℃.
The clear liquid of the vacuum flash crystallization system enters the cooling crystallization system, and the temperature of the cooling crystallization system is 20-30 ℃.
Compared with the prior art, the invention has the beneficial effects that: according to the invention, freezing crystallization, evaporation crystallization, vacuum flash crystallization and cooling crystallization technologies are adopted to fully separate the salt components in the raw material liquid, so that the generation of mixed salt is avoided, the industrial salt purity is high, and the recycling is realized;
in combination with component analysis of raw materials, the sulfate radical content in the raw materials is high, the sodium ion content in clear liquid of an evaporative crystallization system is high, and a large amount of sodium chloride is generated by direct cooling crystallization to influence the quality of potassium chloride, so that in order to separate all salt components in the raw materials and ensure the quality of product salt, proper treatment methods are required to be selected and combined to realize recycling of high-salt wastewater and produce high-purity industrial salt;
separating sodium sulfate decahydrate by adopting a freezing crystallization system, preparing a sodium chloride product by adopting an evaporation crystallization system, recycling part of sodium chloride by adopting a flash cooling crystallization system, and producing potassium chloride by adopting the cooling crystallization system;
the method realizes the salt separation and purification of three salts in a quaternary water salt system, reduces the waste of resources, obtains the industrial salt product with high purity, simultaneously reduces the energy consumption of the system by recovering the heat in the system through the preheater, and can be applied to actual industrial production.
Drawings
FIG. 1 is a salt separation process flow diagram of a quaternary water salt system of the invention;
FIG. 2 is a workflow diagram of a quaternary water salt system salt separation process of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1-2, the present invention provides a technical solution: a quaternary water salt system salt separation process, comprising: the salt separation process comprises the following steps:
s1: preparing raw materials, wherein the water quality of the raw materials contains K + 、Na + 、Cl - 、SO 4 2- ；
S2: the raw materials enter a freezing and crystallizing system through a plate-type precooler, and the freezing and crystallizing system can lead SO to be discharged 4 2- Separating out sodium sulfate decahydrate, and separating out the sodium sulfate decahydrate from the raw materials through a freezing crystallization system;
s3: the clear liquid of the freezing crystallization system enters an evaporation crystallization system through a plate-type precooler, a salt mixing buffer tank and a condensate water preheater to generate sodium chloride products;
s4: condensed water in the evaporative crystallization system can flow back into the condensed water preheater, and the condensed water preheater can discharge the condensed water outwards;
s5: feeding clear liquid discharged from the evaporation crystallization system into a vacuum flash crystallization system, cooling to separate out mixed salt, wherein the main component of the mixed salt is sodium chloride, and returning the mixed salt to the evaporation crystallization system after the mixed salt is dissolved back for continuous evaporation concentration to produce sodium chloride products;
s6: the evaporation crystallization system flows downwards, so that the potassium chloride enters the vacuum flash crystallization system, and clear liquid of the vacuum flash crystallization system enters the cooling crystallization system to separate out potassium chloride products;
s7: and returning the clear liquid of the cooling crystallization system to the raw material buffer tank.
The freezing end temperature of the freezing crystallization system is 0 ℃.
The discharge efficiency temperature of the evaporative crystallization system is set to be 100 ℃.
And the clear liquid discharged by the evaporation crystallization system enters a vacuum flash crystallization system for cooling, and the temperature of the vacuum flash crystallization system is 50-55 ℃.
First embodiment: selecting the temperature in a vacuum flash crystallization system to be 52 ℃;
second embodiment: selecting the temperature in a vacuum flash crystallization system to be 53 ℃;
third embodiment: the temperature in the vacuum flash crystallization system is selected to be 54 ℃;
the clear liquid of the vacuum flash crystallization system enters the cooling crystallization system, and the temperature of the cooling crystallization system is 20-30 ℃.
First embodiment: the temperature in the cooling crystallization system is selected to be 22 ℃;
second embodiment: selecting the temperature in a cooling crystallization system to be 25 ℃;
third embodiment: the temperature in the cooling crystallization system is selected to be 28 ℃;
in particular, when in use, the water quality of the inlet water contains a large amount of K + 、Na + 、Cl - 、SO 4 2- According to Na at different temperatures 2 SO 4 /Na 2 SO 4· 10H 2 The solubility of O in water is known, na 2 SO 4 /Na 2 SO 4· 10H 2 The solubility of O is minimum at 0 ℃;
na at this temperature 2 SO 4 Maximum dissolved gram number in 100g water is 4.5g, na 2 SO 4· 10H 2 The maximum dissolved gram number of O in 100g of water is 5.0g, na 2 SO 4 In the case of freeze crystallization with Na 2 SO 4· 10H 2 Form precipitation of OTherefore, the raw materials are firstly frozen and crystallized in a freezing and crystallizing system, the freezing end temperature of the freezing and crystallizing system is 0 ℃, so that Na is obtained 2 SO 4· 10H 2 O is fully separated out, SO that SO in clear liquid is reduced 4 2- Is reduced in SO content 4 2- Influence on the quality of salt in the back-end process;
the clear liquid of the freezing crystallization system enters a plate-type precooler to exchange heat with the raw materials from a raw material buffer tank, then enters a salt mixing buffer tank, the heat of the system is recovered, naCl is firstly precipitated in the evaporation crystallization system according to the analysis of water quality components, according to the basic principle of 'Gao Wenxi sodium and low-temperature potassium precipitation', the discharge efficiency temperature of an evaporative crystallization system is set to be 100 ℃, naCl products are discharged, condensed water generated by the system exchanges heat with materials from a salt mixing buffer tank, and the heat of the system is recovered;
because NaCl in the discharged clear liquid of the evaporative crystallization system is in a saturated state, the NaCl content is high, a large amount of NaCl is separated out when the evaporative crystallization system is directly cooled and crystallized, the quality of KCl is influenced, and the quality of KCl is influenced by crystal explosion and the granularity of KCl is influenced, so that the discharged clear liquid of the evaporative crystallization system enters a vacuum flash crystallization system for cooling, the temperature is between 50 and 55 ℃, and the specific first embodiment: the temperature in the vacuum flash crystallization system was chosen to be 52 ℃, second example: the temperature in the vacuum flash crystallization system was chosen to be 53 ℃ and in the third example: selecting a vacuum flash crystallization system with a temperature of 54 ℃, wherein the separated salt is mixed salt, the main component is sodium chloride, and the mixed salt is dissolved back into a mixed salt buffer tank;
clear liquid of vacuum flash crystallization system enters a cooling crystallization system, the temperature is between 20 and 30 ℃, and the specific first embodiment is as follows: the temperature in the cooling crystallization system was chosen to be 22 ℃, second example: the temperature in the cooling crystallization system was chosen to be 25 ℃ and in the third example: the temperature in the cooling crystallization system is selected to be 28 ℃; thereby separating out potassium chloride at low temperature, and returning the clear liquid of the cooling crystallization system to the raw material buffer tank, thereby realizing zero discharge of wastewater.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (6)
1. A quaternary water salt system salt separation process, which is characterized by comprising the following steps: the salt separation process comprises the following steps:
s1: preparing raw materials, wherein the water quality of the raw materials contains K + 、Na + 、Cl - 、SO 4 2- ；
S2: the raw material enters a freezing and crystallizing system through a plate-type precooler, and the freezing and crystallizing system lets SO 4 2- Separating out sodium sulfate decahydrate, and separating out the sodium sulfate decahydrate from the raw materials through a freezing crystallization system;
s3: the clear liquid of the freezing crystallization system enters an evaporation crystallization system through a plate-type precooler, a salt mixing buffer tank and a condensate water preheater to generate sodium chloride products;
s4: condensed water in the evaporative crystallization system can flow back into the condensed water preheater, and the condensed water preheater discharges the condensed water outwards;
s5: feeding the clear liquid discharged from the evaporation crystallization system into a vacuum flash crystallization system, cooling to separate out mixed salt, returning the mixed salt to the evaporation crystallization system after the mixed salt is dissolved back, and continuing to evaporate and concentrate to produce sodium chloride products;
s6: the evaporation crystallization system flows downwards, so that the potassium chloride enters the vacuum flash crystallization system, and clear liquid of the vacuum flash crystallization system enters the cooling crystallization system to separate out potassium chloride products;
s7: and returning the clear liquid of the cooling crystallization system to the raw material buffer tank.
2. The quaternary water salt system salt splitting process of claim 1, wherein the freezing end temperature of the freezing crystallization system is 0 ℃.
3. The quaternary water salt system salt separating process according to claim 1, wherein the discharge efficiency temperature of the evaporative crystallization system is set to be 100 ℃.
4. A quaternary water salt system salt separating process according to claim 1, wherein, and the clear liquid discharged by the evaporation crystallization system enters a vacuum flash crystallization system for cooling, and the temperature of the vacuum flash crystallization system is 50-55 ℃.
5. The quaternary water salt system salt separating process according to claim 1, wherein the clear liquid of the vacuum flash crystallization system enters the cooling crystallization system, and the temperature of the cooling crystallization system is 20-30 ℃.
6. The process according to claim 1, wherein the main component of the complex salt is sodium chloride.
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| CN202310351273.XA CN116253335A (en) | 2023-04-04 | 2023-04-04 | Salt separation process of quaternary water salt system |
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| CN202310351273.XA CN116253335A (en) | 2023-04-04 | 2023-04-04 | Salt separation process of quaternary water salt system |
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