CN112897552A - Method for co-production of salt and calcium - Google Patents
Method for co-production of salt and calcium Download PDFInfo
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- CN112897552A CN112897552A CN202110151264.7A CN202110151264A CN112897552A CN 112897552 A CN112897552 A CN 112897552A CN 202110151264 A CN202110151264 A CN 202110151264A CN 112897552 A CN112897552 A CN 112897552A
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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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- 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
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Abstract
The invention discloses a method for co-production of salt and calcium, which comprises a salt making process, a calcium liquid primary concentration process and a calcium liquid secondary concentration process, wherein the salt making process obtains a feed liquid containing 22-29% of calcium chloride, the calcium liquid primary concentration process obtains a feed liquid containing 36-45% of calcium chloride, and the calcium liquid secondary concentration process obtains a feed liquid containing 74-78% of calcium chloride. The method for co-production of the salt and the calcium solves the problem of salt production by taking calcium halide containing calcium chloride and sodium chloride as raw materials, better solves the problems of utilization rate of sodium chloride resources and comprehensive utilization of the calcium chloride resources, and produces superior refined salt/scattered wet salt products and superior calcium chloride dihydrate/liquid calcium products in a set of devices.
Description
Technical Field
The invention relates to the technical field of salt production, in particular to a method for co-producing salt and calcium.
Background
Calcium chloride (chemical formula is CaCl)2) Is typical ionic halide, is white and hard fragments or particles at room temperature, and is a widely used raw material for chemical reagents, medical raw materials, food additives, feed additives, metal calcium manufacturing and the like. The calcium chloride can be used as drying agent, refrigerant, building antifreeze, road dust collector, antifogging agent, fabric fireproofing agent, food antiseptic, chelating agent, curing agent, calcium enhancer, pickling agent, tissue modifier, magnesium and fluorine poisoning relief, vitamin D deficiency rickets calcium salt supplement, lubricating oil additive, analytical reagent, calcium salt manufacturing raw material, etc.
The production method for preparing salt from brine comprises the following steps: a vacuum salt making method, a salt and nitrate co-production method and the like. The vacuum salt making method is a salt making method that brine is evaporated in multiple vacuum evaporation tanks in multiple effects, and pressure drop difference among the tanks forms gradient boiling point and secondary steam is utilized for multiple times; the device is designed with two main processes of evaporation crystallization and dehydration drying; has the advantages of high mechanization and automation degree, low energy consumption, low production cost and the like. The vacuum salt making method is more suitable for the salt making production of low-nitrate brine containing low sodium sulfate and sodium chloride or gypsum type brine containing calcium sulfate and sodium chloride with low solubility, a small amount of salt making mother liquor discharged by the device can obtain high-quality refined salt products, but for the salt making production of high-nitrate brine containing high sodium sulfate and sodium chloride or calcium brine containing high calcium chloride and sodium chloride, a large amount of salt making mother liquor needs to be discharged by the device to ensure the salt quality, so that the brine utilization rate is low, the energy consumption is high, the environmental protection pressure is high, and the like. Namely, the vacuum salt preparation method is not suitable or uneconomical for the salt preparation from high-nitrate brine or calcium brine.
The method for co-producing salt and sodium sulfate is a research and development process technology aiming at the production of nitrate marinating salt with higher sodium sulfate content and sodium chloride, and NaCl-Na in a certain temperature range is utilized2SO4-H2In O water salt system, NaCl solubility increases with temperature, Na2SO4The solubility is reduced along with the temperature rise, and the salt is separated at low temperature and nitre is separated at high temperature in the production process, and the salt of the device product does not contain nitre and nitre. Nitre bittern headFirstly, multiple-effect evaporation is carried out in a plurality of evaporation tanks in a vacuum state in a salt working procedure, sodium chloride is crystallized and separated out, sodium sulfate is only increased in concentration and is not crystallized and separated out, and mother liquor is transferred into a saltpeter working procedure and is evaporated and circulated in the saltpeter working procedure; in the nitrate procedure, the first-effect sodium sulfate is crystallized and separated out, the concentration of salt is improved and not separated out, the temperature of the material liquid in a flash tank and an evaporation tank at the back is reduced, the salt is separated out after being thickened, and the fine nitrate crystals in the material liquid are redissolved and only the concentration of the nitrate in the material liquid is improved and not separated out; secondary steam and condensed water in the device are recycled for multiple times; the salt and nitrate co-production method has the characteristics of advanced process, low energy consumption, high and stable product quality and the like, and takes the nitrate bittern as the raw material to produce high-quality refined salt products and co-produce high-quality industrial anhydrous sodium sulfate products. Because the solubility characteristic of calcium chloride is completely different from that of sodium sulfate, the calcium brine containing calcium chloride and sodium chloride can only produce high-quality refined salt products by adopting a salt and nitrate co-production method, and in order to ensure the salt quality, a large amount of salt-making mother liquor containing calcium chloride needs to be discharged from a device, so that the brine utilization rate is low, the energy consumption is high, the environmental protection pressure is high, and the like. I.e. the co-production method of saltpeter is not suitable or economical for the production of calcium marinated salt.
The resource advantages of sodium sulfate type rock salt ores and brine well dissolving cavities for salt production for many years are fully utilized, a salt-nitrate co-production device, a soda ash device and a salt-calcium co-production device are built to form a salt-alkali-calcium combined production economic mode, salt making condensate water is recycled, brine is extracted from brine-making spent water and alkali-making fresh calcium liquid which are all injected into a well, and the extracted brine is a green production mode of salt-making alkali-making raw materials. With the continuous injection of the alkali-making light calcium liquid into the well for brine mining, brine mined from the sodium sulfate type rock salt mine is converted from nitrate brine containing sodium sulfate and sodium chloride into calcium brine containing calcium chloride and sodium chloride, the chemical properties and the production flow of associated resources of calcium chloride and sodium sulfate contained in the brine are completely different, neither the vacuum salt-making method nor the salt-nitrate co-production method can realize the production of calcium chloride products from the calcium brine containing calcium chloride and sodium chloride, and a large amount of mother liquid containing calcium chloride needs to be discharged to ensure the salinity, so that the utilization rate of the brine of the device is low, the heat loss is large, the calcium chloride resource is not utilized, the environmental protection pressure is large, and the like.
Disclosure of Invention
Based on the method, the invention provides a method for co-production of salt and calcium, which utilizes the respective solubility physical characteristics of sodium chloride and calcium chloride and uses calcium halide containing calcium chloride and sodium chloride to produce refined salt products and co-produce calcium chloride dihydrate products in the same device, so that calcium chloride resources are comprehensively utilized, the utilization rate of the brine is improved, the energy consumption is reduced, and the like.
In order to achieve the above purpose, the invention provides the following technical scheme:
a method for co-production of salt and calcium comprises a salt making process, a calcium liquid primary concentration process and a calcium liquid secondary concentration process, wherein the salt making process obtains a feed liquid containing 22% -29% of calcium chloride, the calcium liquid primary concentration process obtains a feed liquid containing 36% -45% of calcium chloride, and the calcium liquid secondary concentration process obtains a feed liquid containing 74% -78% of calcium chloride.
Further, the salt making process comprises the following steps:
1) preheating calcium halide by a preheater, adding the calcium halide into a calcium halide barrel after preheating, and conveying the calcium halide in the calcium halide barrel to an evaporation tank through countercurrent feeding for multi-effect vacuum evaporation or heat pump and multi-effect evaporation to obtain sodium chloride crystals and feed liquid with the calcium chloride concentration of 22-29%;
2) discharging the sodium chloride crystals obtained in the salt making step 1) to a salt slurry barrel through a salt leg of an evaporation tank, thickening the salt slurry in the salt slurry barrel, and then performing centrifugal dehydration to obtain wet salt, wherein one part of the wet salt is a scattered wet salt product, and one part of the wet salt is dried and packaged to obtain a refined salt product;
3) feeding the feed liquid with the calcium chloride concentration of 22% -29% obtained in the step 1) into a cyclone for sedimentation separation, mixing the underflow salt slurry obtained after sedimentation separation with the calcium halide obtained in the step 1), and repeating the step 1) of the salt making procedure;
4) and (3) settling and separating the supernatant subjected to the settling and separating in the step 3) again, repeating the step 1) of the salt making procedure on the lower salt slurry subjected to the settling and separating again, pumping the gypsum slurry out of the system to remove the mine brine, and introducing the supernatant subjected to the settling and separating again into a mother liquor barrel, wherein the concentration of calcium chloride in the supernatant is 22-29%.
The primary calcium liquid concentration process comprises the following steps:
1) pumping the mother liquor of calcium chloride in the mother liquor barrel in the step 4) of the salt making procedure into an evaporation tank in a counter-current manner for multi-effect vacuum evaporation and concentration to obtain feed liquor with the calcium chloride concentration of 36-45%;
2) and (3) carrying out sedimentation separation on the feed liquid obtained in the step 1) of primary concentration of the calcium liquid, repeating the step 1) of the salt making procedure on the lower salt slurry after sedimentation separation, and sending the supernatant liquid after sedimentation separation into a primary mother liquid barrel, wherein the concentration of calcium chloride in the feed liquid in the primary mother liquid barrel is 36-45%.
The secondary calcium liquid concentration process comprises the following steps:
feeding the feed liquid in the primary mother liquid barrel in the primary calcium liquid concentration step 2) in a countercurrent mode, pumping the feed liquid into an evaporation tank for secondary vacuum evaporation concentration to obtain feed liquid with the calcium chloride concentration of 74-78%, sending the feed liquid containing 74-78% of calcium chloride to a calcium tablet machine for cooling and tablet forming to obtain calcium chloride dihydrate tablets, and drying and packaging the calcium chloride dihydrate tablets to obtain a calcium chloride dihydrate product.
The method for co-production of calcium chloride and sodium chloride aims at calcium halide containing calcium chloride and sodium chloride, and utilizes the characteristics that the solubility of different substances which are easily dissolved in water is influenced by temperature to be different, and NaCl-CaCl is added in a certain temperature range2-H2In the water salt system of O, the solubility of sodium chloride is not changed greatly along with the temperature, and the solubility of calcium chloride is obviously changed along with the temperature, and calcium halide is used as a raw material to produce high-quality refined salt products and co-produce calcium chloride products. Calcium bittern containing calcium chloride and sodium chloride is firstly concentrated, crystallized and separated out by sodium chloride through multiple-effect vacuum evaporation in a salt manufacturing process, calcium chloride is only concentrated but not crystallized and separated out, and salt slurry is centrifugally dehydrated, dried and packaged into a refined salt product; the mother liquor containing calcium chloride in the salt making process is transferred to a calcium liquor concentration process to be continuously concentrated and thickened through multi-effect vacuum evaporation, the mother liquor in the calcium liquor concentration process is transferred to a calcium liquor high-temperature process to be further concentrated and concentrated to product concentration through double-effect evaporation, the mother liquor in the calcium liquor high-temperature process is subjected to a calcium chloride flaking process to be flaked and then to a calcium chloride dihydrate drying process, and a calcium chloride dihydrate product is obtained through packaging; the salt of the product does not contain calcium chloride, and the calcium chloride product does not contain salt. The heat of the secondary steam and the condensed water in each process can be recycled for multiple timesThe application is as follows. The method for co-producing the salt and the calcium takes the calcium brine as the raw material, produces high-quality refined salt products and co-produces calcium chloride products in a set of devices, and has the characteristics of advanced process, low energy consumption, high brine utilization rate, comprehensive resource utilization, environmental protection and the like.
Further, the calcium halide in the step 1) of the salt making procedure is calcium halide which is obtained from mines and contains calcium chloride and sodium chloride, and the content of calcium chloride in the calcium halide is 1.25-6.5%.
Further, the multiple-effect vacuum evaporation in the step 1) of the salt making procedure is four-effect, five-effect or six-effect.
Further, in the step 2) of the salt making procedure, the sodium chloride crystals are discharged from the second effect to a salt slurry barrel through 2 or 3 or 4 or 5 evaporator salt legs.
Furthermore, the second effect of the second effect is the third effect or the second to the fourth effect or the second to the fifth effect or the second to the sixth effect.
Further, the multi-effect vacuum evaporation in the step 1) of the primary calcium liquid concentration process is two-effect or three-effect.
Furthermore, steam and condensed water heat generated by multi-effect vacuum evaporation can be recycled for multiple times by utilizing the pressure difference between tanks, and gypsum, condensed water and salt-making waste water with miscellaneous water generated in the production process are used for returning to a mine injection well to extract brine.
Compared with the prior art, the method for co-producing the salt and the calcium has the following beneficial effects that:
the method for co-production of the salt and the calcium solves the problems of salt production by taking calcium bittern containing calcium chloride and sodium chloride as raw materials, better solves the problems of utilization rate of sodium chloride resources, comprehensive utilization of calcium chloride resources and environmental protection, produces high-grade refined salt/scattered wet salt products in a set of devices, and co-produces high-grade calcium chloride dihydrate/liquid calcium products.
In the method for co-producing the calcium chloride, the multiple-effect vacuum evaporation, the secondary steam and the condensed water heat can be recycled for multiple times, the heat efficiency of the device is high, and the comprehensive utilization of resources is realized by the calcium chloride. The salt-making mother liquor containing calcium chloride is not discharged outside, salt-making gypsum and the like return to a mine injection well along with salt-making waste water for brine extraction, water resources are recycled, calcium chloride products are co-produced, the calcium balance capacity is improved, the adaptability and sustainability of a saline-alkali calcium combined production economic mode are enhanced, and the method for co-producing the salt and the calcium has the characteristics of advanced process, high product quality, stable operation, low energy consumption, high resource utilization rate, environmental friendliness and the like.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a process flow diagram of the combined production of calcium chloride and calcium carbonate according to the embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
A method for coproducing salt and calcium comprises a salt production process, a calcium liquid primary concentration process and a calcium liquid secondary concentration process,
the salt making process comprises the following steps:
1) preheating calcium halide containing calcium chloride and sodium chloride obtained from mines by a preheater, wherein the content of calcium chloride in the calcium halide is 6.5%, adding the calcium halide into a calcium halide barrel after preheating, and conveying the calcium halide in the calcium halide barrel to an evaporation tank through countercurrent feeding for four-effect vacuum evaporation to obtain sodium chloride crystals and feed liquid with the calcium chloride concentration of 29%;
2) discharging the sodium chloride crystals obtained in the salt making step 1) from the fourth effect to a salt slurry barrel through 3 evaporation tank salt legs, thickening the salt slurry in the salt slurry barrel, and then performing centrifugal dehydration to obtain wet salt, wherein one part of the wet salt is a scattered wet salt product, and one part of the wet salt is dried and packaged to obtain a refined salt product;
3) feeding the feed liquid with 29 percent of calcium chloride concentration in the step 1) into a cyclone for sedimentation separation, mixing the underflow salt slurry after sedimentation separation with the calcium halide in the step 1), and repeating the step 1) of the salt making procedure;
4) and (3) settling and separating the supernatant subjected to the settling and separating in the step 3) again, repeating the step 1) of the salt making procedure on the lower salt slurry subjected to the settling and separating again, pumping the gypsum slurry out of the system to remove the mine brine, and introducing the supernatant subjected to the settling and separating again into a mother liquor barrel, wherein the concentration of calcium chloride in the supernatant is 29%.
The primary calcium liquid concentration process comprises the following steps:
1) feeding the mother liquor of calcium chloride in the mother liquor barrel in the step 4) of the salt making procedure in a countercurrent manner, pumping the mother liquor into an evaporation tank for triple-effect vacuum evaporation and concentration to obtain feed liquor with the concentration of the calcium chloride of 45%;
2) and (3) carrying out sedimentation separation on the feed liquid obtained in the step 1) of primary concentration of the calcium liquid, repeating the step 1) of the salt making procedure on the lower salt slurry after sedimentation separation, and sending the supernatant liquid after sedimentation separation into a primary mother liquid barrel, wherein the calcium chloride concentration of the feed liquid in the primary mother liquid barrel is 45%.
The secondary calcium liquid concentration process comprises the following steps:
feeding the feed liquid in the primary mother liquid barrel in the primary calcium liquid concentration step 2) in a countercurrent mode, pumping the feed liquid into an evaporation tank for secondary vacuum evaporation concentration to obtain feed liquid with the calcium chloride concentration of 78%, sending the feed liquid containing 78% of calcium chloride to a calcium tablet machine for cooling and tablet forming to obtain calcium chloride dihydrate tablets, and drying and packaging the calcium chloride dihydrate tablets to obtain a calcium chloride dihydrate product.
The steam and condensed water heat generated by the four-effect and two-effect vacuum evaporation can be recycled for multiple times by utilizing the pressure difference between the tanks, and gypsum, condensed water and salt-making waste water with impurity water generated in the production process are used for returning to the mine injection well to extract brine.
Example 2
A method for co-production of salt and calcium comprises a salt making process, a primary calcium liquid concentration process and a secondary calcium liquid concentration process, wherein the salt making process comprises the following steps:
1) preheating calcium halide containing calcium chloride and sodium chloride obtained from mines by a preheater, wherein the content of calcium chloride in the calcium halide is 1.25%, adding the calcium halide into a calcium halide barrel after preheating, and conveying the calcium halide in the calcium halide barrel to an evaporation tank through countercurrent feeding for five-effect vacuum evaporation to obtain sodium chloride crystals and feed liquid with the concentration of calcium chloride of 22%;
2) discharging the sodium chloride crystals obtained in the salt making step 1) from the fifth effect to a salt slurry barrel through 2 evaporation tank salt legs, thickening the salt slurry in the salt slurry barrel, and then performing centrifugal dehydration to obtain wet salt, wherein one part of the wet salt is a scattered wet salt product, and one part of the wet salt is dried and packaged to obtain a refined salt product;
3) feeding the feed liquid with the calcium chloride concentration of 22% in the step 1) into a cyclone for sedimentation separation, mixing the underflow salt slurry after sedimentation separation with the calcium halide in the step 1), and repeating the step 1) of the salt making procedure;
4) and (3) settling and separating the supernatant subjected to the settling separation in the step 3) again, pumping the gypsum slurry on the lower part subjected to the settling separation again out of the system to remove the brine mining slurry from the mine, repeating the step 1) of the salt making procedure, and introducing the supernatant subjected to the settling separation again into a mother liquor barrel, wherein the concentration of calcium chloride in the supernatant is 22%.
The primary calcium liquid concentration process comprises the following steps:
1) feeding the mother liquor of calcium chloride in the mother liquor barrel in the step 4) of the salt making procedure in a countercurrent manner, pumping the mother liquor into an evaporation tank for triple-effect vacuum evaporation and concentration to obtain feed liquor with the concentration of the calcium chloride of 36%;
2) and (3) performing sedimentation separation on the feed liquid obtained in the step 1) of primary concentration of the calcium liquid, repeating the step 1) of the salt making procedure on the lower salt slurry after sedimentation separation, pumping the gypsum slurry out of the system to remove the mine brine, and sending the supernatant liquid after sedimentation separation into a primary mother liquid barrel, wherein the calcium chloride concentration of the feed liquid in the primary mother liquid barrel is 36%.
The secondary calcium liquid concentration process comprises the following steps:
feeding the feed liquid in the primary mother liquid barrel in the primary calcium liquid concentration step 2) in a countercurrent mode, pumping the feed liquid into an evaporation tank for secondary vacuum evaporation concentration to obtain feed liquid with the calcium chloride concentration of 74%, sending the feed liquid containing 74% of calcium chloride to a calcium tablet machine for cooling and tablet forming to obtain calcium chloride dihydrate tablets, and drying and packaging the calcium chloride dihydrate tablets to obtain a calcium chloride dihydrate product.
The steam and condensed water heat generated by the four-effect and three-effect evaporation can be recycled for multiple times by utilizing the pressure difference between the tanks, and gypsum, condensed water and salt-making waste water with miscellaneous water generated in the production process are used for returning to the mine injection well to extract brine.
Steam and condensed water heat generated by five-effect and three-effect vacuum evaporation can be recycled for multiple times by utilizing the pressure difference between tanks, and gypsum, condensed water and salt-making waste water with miscellaneous water generated in the production process are used for returning to a mine injection well to extract brine.
Example 3
A method for co-production of salt and calcium comprises a salt making process, a primary calcium liquid concentration process and a secondary calcium liquid concentration process, wherein the salt making process comprises the following steps:
1) preheating calcium halide containing calcium chloride and sodium chloride obtained from mines by a preheater, wherein the content of calcium chloride in the calcium halide is 5%, adding the calcium halide into a calcium halide barrel after preheating, and conveying the calcium halide in the calcium halide barrel to an evaporation tank through countercurrent feeding for six-effect vacuum evaporation to obtain sodium chloride crystals and feed liquid with the calcium chloride concentration of 25%;
2) discharging the sodium chloride crystals obtained in the salt making step 1) from the sixth effect to a salt slurry barrel through 3 evaporation tank salt legs, thickening the salt slurry in the salt slurry barrel, and then performing centrifugal dehydration to obtain wet salt, wherein one part of the wet salt is a scattered wet salt product, and one part of the wet salt is dried and packaged to obtain a refined salt product;
3) feeding the feed liquid with the calcium chloride concentration of 25% in the step 1) into a cyclone for sedimentation separation, mixing the underflow salt slurry after sedimentation separation with the calcium halide in the step 1), and repeating the step 1) of the salt making procedure;
4) and (3) settling and separating the supernatant subjected to the settling separation in the step 3) again, repeating the step 1) of the salt making procedure on the lower salt slurry subjected to the settling separation again, pumping the gypsum slurry out of the system to remove the mine brine, and introducing the supernatant subjected to the settling separation again into a mother liquor barrel, wherein the concentration of calcium chloride in the supernatant is 25%.
The primary calcium liquid concentration process comprises the following steps:
1) feeding the mother liquor of calcium chloride in the mother liquor barrel in the step 4) of the salt making procedure in a countercurrent manner, pumping the mother liquor into an evaporation tank for triple-effect vacuum evaporation and concentration to obtain feed liquor with the concentration of the calcium chloride of 40%;
2) and (3) carrying out sedimentation separation on the feed liquid obtained in the step 1) of primary concentration of the calcium liquid, repeating the step 1) of the salt making procedure on the lower salt slurry after sedimentation separation, and sending the supernatant liquid after sedimentation separation into a primary mother liquid barrel, wherein the concentration of calcium chloride in the feed liquid in the primary mother liquid barrel is 40%.
The secondary calcium liquid concentration process comprises the following steps:
feeding the feed liquid in the primary mother liquid barrel in the primary calcium liquid concentration step 2) in a countercurrent mode, pumping the feed liquid into an evaporation tank for secondary vacuum evaporation concentration to obtain feed liquid with the calcium chloride concentration of 76%, sending the feed liquid containing 76% of calcium chloride to a calcium tablet machine for cooling and tablet forming to obtain calcium chloride dihydrate tablets, and drying and packaging the calcium chloride dihydrate tablets to obtain a calcium chloride dihydrate product.
The steam and condensed water heat generated by the four-effect and three-effect evaporation can be recycled for multiple times by utilizing the pressure difference between the tanks, and gypsum, condensed water and salt-making waste water with miscellaneous water generated in the production process are used for returning to the mine injection well to extract brine.
Steam and condensed water heat generated by six-effect and two-effect vacuum evaporation can be recycled for multiple times by utilizing the pressure difference between tanks, and gypsum, condensed water and salt-making waste water with miscellaneous water generated in the production process are used for returning to a mine injection well to extract brine.
Comparative example 1
The difference from the example 3 is that the multi-effect vacuum evaporation in the salt manufacturing procedure of the comparative example 1 is three-effect evaporation.
Comparative example 2
The difference from example 3 is that the multi-effect vacuum evaporation in the salt manufacturing process of comparative example 2 is seven-effect evaporation.
Comparative example 3
The difference from the example 3 is that the multi-effect vacuum evaporation in the primary calcium solution concentration process of the comparative example 3 is one-effect evaporation.
Comparative example 4
The difference from example 3 is that the secondary concentration step of the calcium solution of comparative example 4 is concentrated by single-effect vacuum evaporation.
The quality of wet salt, refined salt, calcium chloride dihydrate and liquid calcium chloride products prepared by the co-production of the salt and the calcium in the embodiments 1 to 3 and the comparative examples 1 to 4 is tested, whether the wet salt and the refined salt meet the top-grade index of the refined industrial salt in the national standard industrial salt (GB/T5462-2015), whether the calcium chloride dihydrate product meets the index of II type calcium chloride in the national standard industrial calcium chloride (GB/T26520-2011) or above, and whether the liquid calcium chloride meets the industrial index.
Wherein, the main quality indexes of the refined industrial salt are as follows:
A) wet salt: NaCl greater than or equal to 96% and H2Less than or equal to 3.00 percent of O, less than or equal to 0.30 percent of calcium and magnesium ions, less than or equal to 0.50 percent of sulfate ions and less than or equal to 0.05 percent of water-insoluble substances.
B) Refined salt: NaCl greater than or equal to 99.1% and H2Less than or equal to 0.3 percent of O, less than or equal to 0.25 percent of calcium and magnesium ions, less than or equal to 0.30 percent of sulfate ions and less than or equal to 0.05 percent of water-insoluble substances.
The main quality indexes of the calcium chloride dihydrate are as follows:
calcium chloride dihydrate: CaCl2Not less than 74.0%, alkalinity [ Ca (OH) ]2Not more than 0.2 percent, not more than 5.0 percent of total alkali metal chloride (calculated by NaCl), not more than 0.15 percent of water insoluble substance, not more than 0.006 percent of iron (Fe), 7.5 to 11.0 percent of PH value and total magnesium (calculated by MgCl)2Calculated as CaSO, is less than or equal to 0.50 percent and sulfate (calculated as CaSO)4Calculated) is less than or equal to 0.05 percent
The test results are shown in table 1 below:
TABLE 1
As can be seen from Table 1, the quality of the wet salt, the refined salt, the calcium chloride dihydrate and the liquid calcium chloride prepared in examples 1 to 3 reached the relevant standards, and the quality of the calcium chloride dihydrate and the liquid calcium chloride prepared in comparative examples 1 to 4 did not reach the relevant standards.
The cost of the vacuum salt making method or the salt and nitrate co-production method is compared with the cost of the examples 1 to 3 and the comparative examples 1 to 4, and the results are shown in table 2:
TABLE 2
As can be seen from table 2, the treatment cost of the salt and calcium co-production method in the embodiments 1 to 3 can be reduced by more than 20% compared with the vacuum salt making method or the salt and nitrate co-production method, which indicates that the salt and calcium co-production method of the present invention has the advantages of low energy consumption, high resource utilization rate, and environmental protection. Compared with the vacuum salt making method or the salt and nitrate co-production method, the treatment cost of the comparative examples 1-4 is increased by more than 15%, which shows that the salt and calcium co-production method has the characteristics of lower energy consumption, higher resource utilization rate and more environmental protection.
The invention also provides a more detailed description of the method for co-producing the salt and the calcium, which is provided by the invention, by combining with a figure 1, wherein a 'first effect salt slurry and mother liquor' in a salt working procedure in the figure 1 is feed liquid with the concentration of 22-29% of calcium chloride obtained after multi-effect evaporation in a step 1) of a salt making working procedure.
The features of the embodiments and embodiments described above may be combined with each other without conflict.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. The method for co-production of salt and calcium is characterized by comprising a salt making process, a calcium liquid primary concentration process and a calcium liquid secondary concentration process, wherein the salt making process obtains a feed liquid containing 22% -29% of calcium chloride, the calcium liquid primary concentration process obtains a feed liquid containing 36% -45% of calcium chloride, and the calcium liquid secondary concentration process obtains a feed liquid containing 74% -78% of calcium chloride.
2. The method for co-production of salt and calcium according to claim 1, wherein the salt manufacturing process comprises the following steps:
1) preheating calcium halide by a preheater, adding the calcium halide into a calcium halide barrel after preheating, and conveying the calcium halide in the calcium halide barrel to an evaporation tank through countercurrent feeding for multi-effect vacuum evaporation or heat pump and multi-effect evaporation to obtain sodium chloride crystals and feed liquid with the calcium chloride concentration of 22-29%;
2) discharging the sodium chloride crystals obtained in the salt making step 1) to a salt slurry barrel through a salt leg of an evaporation tank, thickening the salt slurry in the salt slurry barrel, and then performing centrifugal dehydration to obtain wet salt, wherein one part of the wet salt is a scattered wet salt product, and one part of the wet salt is dried and packaged to obtain a refined salt product;
3) feeding the feed liquid with the calcium chloride concentration of 22% -29% obtained in the step 1) into a cyclone for sedimentation separation, mixing the underflow salt slurry obtained after sedimentation separation with the calcium halide obtained in the step 1), and repeating the step 1) of the salt making procedure;
4) settling and separating the supernatant subjected to the settling and separating in the step 3) again, repeating the step 1) of the salt making procedure on the lower salt slurry subjected to the settling and separating again, pumping the gypsum slurry out of the system to remove the mine brine, and introducing the supernatant subjected to the settling and separating again into a mother liquor barrel, wherein the concentration of calcium chloride in the supernatant is 22-29%;
the primary calcium liquid concentration process comprises the following steps:
1) pumping the mother liquor of calcium chloride in the mother liquor barrel in the step 4) of the salt making procedure into an evaporation tank in a counter-current manner for multi-effect vacuum evaporation and concentration to obtain feed liquor with the calcium chloride concentration of 36-45%;
2) carrying out sedimentation separation on the feed liquid obtained in the step 1) of primary concentration of the calcium liquid, repeating the step 1) of the salt making procedure on the lower salt slurry after sedimentation separation, and sending the supernatant liquid after sedimentation separation into a primary mother liquid barrel, wherein the concentration of calcium chloride in the feed liquid in the primary mother liquid barrel is 36-45%;
the secondary calcium liquid concentration process comprises the following steps:
feeding the feed liquid in the primary mother liquid barrel in the primary calcium liquid concentration step 2) in a countercurrent mode, pumping the feed liquid into an evaporation tank for secondary vacuum evaporation concentration to obtain feed liquid with the calcium chloride concentration of 74-78%, sending the feed liquid containing 74-78% of calcium chloride to a calcium tablet machine for cooling and tablet forming to obtain calcium chloride dihydrate tablets, and drying and packaging the calcium chloride dihydrate tablets to obtain a calcium chloride dihydrate product.
3. The method for co-production of salt and calcium according to claim 2, wherein the calcium halide obtained in step 1) of the salt production process is calcium halide containing calcium chloride and sodium chloride, and the content of calcium chloride in the calcium halide is 1.25-6.5%.
4. The method for co-production of salt and calcium according to claim 2, wherein the multi-effect vacuum evaporation in step 1) of the salt-making process is four-effect, five-effect or six-effect.
5. The method for co-production of salt and calcium according to claim 2, wherein the sodium chloride crystals in step 2) of the salt production process are discharged from the second effect to a salt slurry barrel through 2 or 3 or 4 or 5 evaporator salt legs.
6. The method for co-production of salt and calcium as claimed in claim 5, wherein the second effect is the second effect and the third effect or the second to the fourth effect or the second to the fifth effect or the second to the sixth effect.
7. The method for co-production of salt and calcium as claimed in claim 2, wherein the multi-effect vacuum evaporation in the step 1) of the primary calcium liquid concentration process is two-effect or three-effect.
8. The method for co-production of salt and calcium as claimed in claim 2, wherein the heat of steam and condensed water generated by multi-effect vacuum evaporation can be recycled for multiple times by utilizing the pressure difference between tanks, and gypsum, condensed water and salt-making waste water of miscellaneous water type generated in the production process are used for returning to a mine injection well to extract brine.
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| CN115770551A (en) * | 2022-12-12 | 2023-03-10 | 江苏苏盐井神股份有限公司 | Method for producing multifunctional dehumidifying agent and bamboo salt by using calcium chloride type brine |
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