CN117263725A - Method for preparing salt bittern from seawater and co-producing magnesium sulfate monohydrate and magnesium potassium sulfate fertilizer - Google Patents
Method for preparing salt bittern from seawater and co-producing magnesium sulfate monohydrate and magnesium potassium sulfate fertilizer Download PDFInfo
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- CN117263725A CN117263725A CN202311213422.2A CN202311213422A CN117263725A CN 117263725 A CN117263725 A CN 117263725A CN 202311213422 A CN202311213422 A CN 202311213422A CN 117263725 A CN117263725 A CN 117263725A
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- 241001131796 Botaurus stellaris Species 0.000 title claims abstract description 56
- 150000003839 salts Chemical class 0.000 title claims abstract description 55
- 239000003337 fertilizer Substances 0.000 title claims abstract description 36
- WZISDKTXHMETKG-UHFFFAOYSA-H dimagnesium;dipotassium;trisulfate Chemical compound [Mg+2].[Mg+2].[K+].[K+].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O WZISDKTXHMETKG-UHFFFAOYSA-H 0.000 title claims abstract description 32
- 229940076230 magnesium sulfate monohydrate Drugs 0.000 title claims abstract description 32
- LFCFXZHKDRJMNS-UHFFFAOYSA-L magnesium;sulfate;hydrate Chemical compound O.[Mg+2].[O-]S([O-])(=O)=O LFCFXZHKDRJMNS-UHFFFAOYSA-L 0.000 title claims abstract description 32
- 239000013535 sea water Substances 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 title claims abstract description 21
- 238000001704 evaporation Methods 0.000 claims abstract description 40
- 230000008020 evaporation Effects 0.000 claims abstract description 38
- 235000002639 sodium chloride Nutrition 0.000 claims description 91
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 72
- 239000012452 mother liquor Substances 0.000 claims description 42
- 239000011780 sodium chloride Substances 0.000 claims description 39
- 239000001103 potassium chloride Substances 0.000 claims description 28
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 claims description 22
- 239000010413 mother solution Substances 0.000 claims description 21
- 239000007788 liquid Substances 0.000 claims description 20
- 238000000926 separation method Methods 0.000 claims description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- 238000001035 drying Methods 0.000 claims description 11
- 229910052943 magnesium sulfate Inorganic materials 0.000 claims description 11
- 235000019341 magnesium sulphate Nutrition 0.000 claims description 11
- BMQVDVJKPMGHDO-UHFFFAOYSA-K magnesium;potassium;chloride;sulfate;trihydrate Chemical compound O.O.O.[Mg+2].[Cl-].[K+].[O-]S([O-])(=O)=O BMQVDVJKPMGHDO-UHFFFAOYSA-K 0.000 claims description 11
- 238000000605 extraction Methods 0.000 claims description 10
- 239000000463 material Substances 0.000 claims description 10
- 238000005406 washing Methods 0.000 claims description 10
- 239000012267 brine Substances 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 9
- 238000001556 precipitation Methods 0.000 claims description 9
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims description 9
- 230000008569 process Effects 0.000 claims description 6
- 238000005188 flotation Methods 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims description 5
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 3
- 229940072033 potash Drugs 0.000 claims description 3
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Substances [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 3
- 235000015320 potassium carbonate Nutrition 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 2
- 238000010025 steaming Methods 0.000 claims description 2
- 239000011777 magnesium Substances 0.000 abstract description 15
- 238000011084 recovery Methods 0.000 abstract description 13
- 238000004519 manufacturing process Methods 0.000 abstract description 12
- 238000002360 preparation method Methods 0.000 abstract description 4
- 230000002452 interceptive effect Effects 0.000 abstract description 2
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 46
- 239000000047 product Substances 0.000 description 28
- 235000011164 potassium chloride Nutrition 0.000 description 23
- 239000011734 sodium Substances 0.000 description 21
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 8
- 229960003390 magnesium sulfate Drugs 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 238000001816 cooling Methods 0.000 description 4
- 238000002425 crystallisation Methods 0.000 description 4
- 230000008025 crystallization Effects 0.000 description 4
- 239000013505 freshwater Substances 0.000 description 4
- 229910001629 magnesium chloride Inorganic materials 0.000 description 4
- 235000011147 magnesium chloride Nutrition 0.000 description 4
- 238000005086 pumping Methods 0.000 description 4
- 238000004062 sedimentation Methods 0.000 description 4
- HAQAPRXIBNGFQH-UHFFFAOYSA-N [V].[K].[Mg] Chemical compound [V].[K].[Mg] HAQAPRXIBNGFQH-UHFFFAOYSA-N 0.000 description 3
- 235000013399 edible fruits Nutrition 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 239000007790 solid phase Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- 241000208125 Nicotiana Species 0.000 description 2
- 235000002637 Nicotiana tabacum Nutrition 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- 244000269722 Thea sinensis Species 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 229910052729 chemical element Inorganic materials 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 229940091250 magnesium supplement Drugs 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 235000013311 vegetables Nutrition 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 1
- NPYPAHLBTDXSSS-UHFFFAOYSA-N Potassium ion Chemical compound [K+] NPYPAHLBTDXSSS-UHFFFAOYSA-N 0.000 description 1
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 229930002875 chlorophyll Natural products 0.000 description 1
- 235000019804 chlorophyll Nutrition 0.000 description 1
- ATNHDLDRLWWWCB-AENOIHSZSA-M chlorophyll a Chemical compound C1([C@@H](C(=O)OC)C(=O)C2=C3C)=C2N2C3=CC(C(CC)=C3C)=[N+]4C3=CC3=C(C=C)C(C)=C5N3[Mg-2]42[N+]2=C1[C@@H](CCC(=O)OC\C=C(/C)CCC[C@H](C)CCC[C@H](C)CCCC(C)C)[C@H](C)C2=C5 ATNHDLDRLWWWCB-AENOIHSZSA-M 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000004043 dyeing Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000000855 fermentation Methods 0.000 description 1
- 230000004151 fermentation Effects 0.000 description 1
- 230000026030 halogenation Effects 0.000 description 1
- 238000005658 halogenation reaction Methods 0.000 description 1
- 150000004688 heptahydrates Chemical class 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 229910001425 magnesium ion Inorganic materials 0.000 description 1
- WRUGWIBCXHJTDG-UHFFFAOYSA-L magnesium sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Mg+2].[O-]S([O-])(=O)=O WRUGWIBCXHJTDG-UHFFFAOYSA-L 0.000 description 1
- PALNZFJYSCMLBK-UHFFFAOYSA-K magnesium;potassium;trichloride;hexahydrate Chemical group O.O.O.O.O.O.[Mg+2].[Cl-].[Cl-].[Cl-].[K+] PALNZFJYSCMLBK-UHFFFAOYSA-K 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 229910001414 potassium ion Inorganic materials 0.000 description 1
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 description 1
- 229910052939 potassium sulfate Inorganic materials 0.000 description 1
- 235000011151 potassium sulphates Nutrition 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000007639 printing Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05D—INORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C; FERTILISERS PRODUCING CARBON DIOXIDE
- C05D1/00—Fertilisers containing potassium
- C05D1/02—Manufacture from potassium chloride or sulfate or double or mixed salts thereof
-
- 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
- C01F5/00—Compounds of magnesium
- C01F5/40—Magnesium sulfates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Fertilizers (AREA)
Abstract
The invention discloses a method for preparing salt bittern from seawater and co-producing magnesium sulfate monohydrate and magnesium potassium sulfate fertilizer, which aims at preparing salt bittern from seawater and combines Na + 、K + 、Mg 2+ 、Cl ‑ 、SO 4 2‑ And H is 2 And the five-membered interactive system of O prepares magnesium sulfate monohydrate by high-temperature evaporation and prepares the potassium magnesium sulfate fertilizer by low-temperature evaporation to realize the co-production of the magnesium sulfate monohydrate and the potassium magnesium sulfate fertilizer by salt and bittern prepared from seawater. The invention realizes the comprehensive utilization of the salt-making bittern from the seawater, and simultaneously realizes the simultaneous preparation of the magnesium sulfate monohydrate and the potassium magnesium sulfate fertilizer, and in addition, the K in the salt-making bittern from the seawater + 、Mg 2+ And SO 4 2‑ The recovery rate of (C) is higher than 80%.
Description
Technical Field
The invention relates to the technical field of salt production from seawater, in particular to a method for producing salt, bittern and co-producing magnesium sulfate monohydrate and magnesium potassium sulfate fertilizer from seawater.
Background
In the sea salt production process, the byproduct of the crude salt is about 1m per 1t production 3 Salt-making waste liquid (commonly called bittern). The bittern contains high concentration of chloride ion, sulfate ion, potassium ion, magnesium ion, sodium ion, etc. and is used in producing industrial salt, magnesium chloride, potassium chloride, etc. The concentration of various chemical elements in the bittern is about 40 times than that of the seawater, and the bittern is an excellent raw material for extracting the chemical elements in the seawater, but is limited by the technical level, and sea salt bittern workers and enterprises are generally in a loss state. The complete comprehensive utilization of bittern is an effective measure for solving the problem of insufficient land resources, is necessary guarantee for realizing energy conservation and emission reduction of sea salt production, and is also a problem that the sea salt bittern worker is urgent to solve.
At present, the recovery treatment of the salt-making bittern from the sea water is generally to evaporate the salt-making bittern from the sea water, add part of old bittern (thick bittern) in the evaporation process, cool and carry out heat preservation sedimentation after the evaporation is finished, discharge the sedimentation to obtain solid, continuously cool to 35-50 ℃, separate the recrystallized solid, wherein the separated solid phase is carnallite mainly containing potassium chloride and magnesium chloride and containing a small amount of sodium chloride; the liquid phase is old brine (also called as thick brine), mainly contains magnesium chloride, and contains a small amount of potassium chloride, sodium chloride and magnesium sulfate. The main products of the method are sodium chloride, magnesium sulfate, potassium chloride and magnesium chloride, and the salinization enterprises for processing salt-making bittern are in a serious deficiency place due to low product market price and high energy consumption. How to reduce the energy consumption and change the product structure is the key of the sea salt bitter halogenation industry and enterprise to be profit.
The third largest resource in ocean resources is natural renewable resources, and industrial magnesium sulfate is generally heptahydrate with molecular formula of MgSO 4 ·7H 2 O. The agricultural magnesium sulfate is generally a hydrate with a molecular formula of MgSO 4 ·H 2 O and magnesium sulfate are important inorganic chemical products, and are widely used in fields of printing and dyeing, medicine, brewing, fermentation industry, pulp industry, fireproof material and the like, and magnesium sulfate monohydrate in agriculture is an important double-nutrient element (sulfur and magnesium) chemical productAnd (5) a fertilizer. In addition, compared with the traditional potassium sulfate product, the potassium magnesium sulfate fertilizer has the advantages that the magnesium medium element is added, the chlorophyll formation can be promoted, the crop yield and quality can be improved, the storage period of fruits can be prolonged, and the potassium magnesium sulfate fertilizer is suitable for being applied to commercial crops such as vegetables, fruit trees, tobacco, tea leaves, flowers and the like.
The main component of the domestic potassium magnesium sulfate fertilizer at the present stage is soft potassium magnesium vanadium dehydration series products, and the molecular formula is K 2 Mg(SO 4 ) 2 ·nH 2 O (n=4 to 6), the execution standard is GB/T20937-2007. The production method of the potassium magnesium sulfate fertilizer in China mainly adopts a conversion-floatation-washing-drying process, namely KCl and MgSO4.7H2O in the potassium mixed salt raw ore are converted into soft potassium magnesium vanadium by adding water, the soft potassium magnesium vanadium is enriched by adopting a floatation process, and the concentrate is washed and dried to obtain a qualified potassium magnesium sulfate fertilizer product. The existing technology is widely applied to salt lake potassium chloride production factories, and has the characteristics of simple technological process, low production cost, high product quality and the like. However, the recovery rate of potassium in the prior art is generally about 65%, and the recovery rate is lower.
Therefore, the natural resource treasury of the ocean is fully utilized, the high added value utilization of bittern resources is realized, the structure of the existing bittern utilization product is changed, the economic benefit of sea salt bittern industry and enterprises is improved, and the preparation of magnesium sulfate monohydrate and magnesium potassium sulfate fertilizer with high recovery rate and low cost is hoped.
The present invention has been made to solve the above problems.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides the method for producing the magnesium sulfate monohydrate and the magnesium potassium sulfate fertilizer by utilizing the seawater to prepare the salt bittern, thereby not only realizing the high added value utilization of bittern resources, but also realizing the preparation of the magnesium sulfate monohydrate and the magnesium potassium sulfate fertilizer with high recovery rate and low cost.
The invention adopts the following technical scheme:
the invention provides a method for preparing salt bittern from seawater and co-producing magnesium sulfate monohydrate and magnesium potassium sulfate fertilizer, which comprises the following steps:
(1) Adding Na into salt-making bittern from sea water 2 SO 4 And MgCl 2 Mixing the solids and adding brine to obtain first mixed brine;
(2) Adding the first mixed brine into a high-temperature evaporator for evaporation and salt precipitation; the evaporation temperature is 90-130 ℃;
(3) Carrying out solid-liquid separation on the materials discharged by the high-temperature evaporator to obtain mixed salt containing magnesium sulfate monohydrate Kie and NaCl and Kie extracting mother liquor;
(4) Separating, washing and drying the mixed salt containing Kie and NaCl obtained by solid-liquid separation in the step (3) to obtain the magnesium sulfate monohydrate MgSO 4 ·H 2 An O product;
(5) The Kie extracting mother liquor is cooled to the temperature of 60 ℃ to 85 ℃ in a constant temperature crystallizer, and Na is added at the same time 2 SO 4 And water for conversion;
(6) Carrying out solid-liquid separation on the material liquid discharged from the crystallizer to obtain mixed salt containing anhydrous kainite Lan and NaCl and Lan extracting mother liquor;
(7) The Lan mother liquor is extracted with KCl and Na 2 SO 4 Mixing, adding into a low-temperature evaporator for evaporation and salt precipitation, wherein the evaporation temperature is 60-85 ℃;
(8) Carrying out solid-liquid separation on the materials discharged by the low-temperature evaporator to obtain mixed salt containing anhydrous kainite Lan and NaCl and a circulating mother solution for Lan extraction;
(9) The Lan circulating mother liquor is extracted with KCl and Na 2 SO 4 Mixing and then entering a low-temperature evaporator for circulation;
(10) And (3) carrying out solid-liquid separation on materials discharged from the constant temperature crystallizer and the low temperature evaporator to obtain mixed salt containing anhydrous kainite Lan and NaCl, and separating, washing and drying to obtain a potash magnesium sulphate fertilizer product.
Preferably, in the step (1), the sea water salt-making bittern contains 50g/L-200g/L NaCl and 100g/L-210g/L MgCl 2 15g/L-45g/L KCl and 40g/L-120g/L MgSO 4 。
Preferably, in step (1), na is added 2 SO 4 The mass is 0-15% of the mass of the bittern, and MgCl is added 2 The mass is 0-15% of the mass of the bittern. Adding Na 2 SO 4 、MgCl 2 According to the mass requirement of the actual salt precipitation phaseThe composition of the bittern of the region is determined by, in particular, na in the bittern of the actual salt precipitation phase region + 、Mg 2+ 、Cl - 、SO 4 2- Optionally adding Na 2 SO 4 、MgCl 2 One or both of them, in most cases Na is added 2 SO 4 、MgCl 2 One of them.
Preferably, in the step (2), the relative bittern steaming water loss rate is 45% -85%.
Preferably, in step (3), the magnesium sulfate monohydrate Kie is MgSO 4 ·H 2 O; in the step (6), the anhydrous kainite Lan is K 2 SO 4 ·2MgSO 4 。
Preferably, in step (5), na is added to the Kie mother liquor after salt precipitation by evaporation at high temperature 2 SO 4 And water, ensuring that the Kie mother liquor is separated out of mixed salt of solid phase Lan and NaCl at the low temperature of 60-85 ℃ after high-temperature evaporation and salt separation. Added Na 2 SO 4 The mass of the water is 0-15% of the mass of the Kie extracting mother liquor, and the mass of the water is 0-10% of the mass of the Kie extracting mother liquor. Adding Na 2 SO 4 The quality of (2) depends on the composition of the actual Kie mother liquor.
Preferably, in step (7), KCl and Na are added to the Lan mother liquor by adding the salt after low temperature crystallization 2 SO 4 Ensures that the mixed salt of solid phase Lan and NaCl can be further separated out by evaporation at the low temperature of 60-85 ℃ after salt precipitation by low-temperature crystallization and Lan mother liquor. KCl is added to extract 0-10% of Lan mother liquor by mass, na is added 2 SO 4 The mass of the mother solution is 0-15% of that of the Lan extraction mother solution, and the relative evaporation rate of the mother solution is 2.5-15%. Adding Na 2 SO 4 And the quality of KCl is determined according to the composition of the actual Lan mother liquor. The evaporation rate of the invention refers to the mass of the evaporation water compared with the mass of the water in the feed liquid
Preferably, in the step (9), the Lan circulating mother liquor after salt precipitation by low-temperature evaporation is obtained by adding KCl and Na 2 SO 4 The circulating mother liquor of the lifting Lan can be circulated back to the low-temperature evaporator to continuously evaporate and separate out mixed salt of solid Lan and NaCl. KCl is added to extract 0-10% of the mass of Lan circulating mother liquor, and Na is added 2 SO 4 The mass of the mother solution is 0-15% of the mass of the Lan circulating mother solution. Adding Na 2 SO 4 And the quality of KCl is determined according to the composition of the actual Lan circulating mother liquor.
Preferably, in the step (10), the mixed salt containing anhydrous kainite Lan and NaCl is subjected to reverse flotation, water washing and drying to obtain a potash magnesium sulphate fertilizer product. In addition, any separation method in the prior art may be used as long as it can separate the anhydrous kainite Lan from NaCl, and is not limited to the reverse flotation described above.
The potassium magnesium sulfate fertilizer product prepared by the invention is suitable for being applied to economic crops such as vegetables, fruit trees, tobacco, tea, flowers and the like, and the prepared magnesium sulfate monohydrate can be used for industry.
Na according to the invention 2 SO 4 、MgCl 2 And KCl is not limited to industrial Na 2 SO 4 、MgCl 2 And KCl products, which can be double salts and solutions containing the corresponding substances.
In the present invention, kie is MgSO 4 ·H 2 O, lan is K 2 SO 4 ·2MgSO 4 。
Compared with the prior art, the invention has the following beneficial effects:
1. the invention aims at the salt-making bittern component of sea water and combines Na + 、K + 、Mg 2+ 、Cl - 、SO 4 2- And H is 2 And the five-membered interactive system of O prepares magnesium sulfate monohydrate by high-temperature evaporation and prepares the potassium magnesium sulfate fertilizer by low-temperature evaporation to realize the co-production of the magnesium sulfate monohydrate and the potassium magnesium sulfate fertilizer by salt and bittern prepared from seawater. The invention realizes the comprehensive utilization of the salt-making bittern from the seawater, and simultaneously realizes the simultaneous preparation of the magnesium sulfate monohydrate and the potassium magnesium sulfate fertilizer, and in addition, the K in the salt-making bittern from the seawater + 、Mg 2+ And SO 4 2- The recovery rate of (C) is higher than 80%.
2. The mass fractions of Mg and Cl in the magnesium sulfate monohydrate product prepared by the invention all reach the standard requirements of HGT 2680-2017 industrial magnesium sulfate, and K in the prepared potassium magnesium sulfate fertilizer product 2 O, mg, S, cl, na the mass fraction reaches GB/T20937-2007 standard requirements of potassium magnesium sulfate fertilizer.
3. The invention realizes the co-production of magnesium sulfate monohydrate and magnesium potassium sulfate fertilizer by preparing salt bittern from sea water, completes the high added value utilization of the salt bittern from sea water, and can obtain 0.015 to 0.065 ton of magnesium sulfate monohydrate and 0.1 to 0.3 ton of magnesium potassium sulfate fertilizer by treating each ton of bittern, wherein the price of the magnesium sulfate monohydrate in the market is about 1800 yuan/ton, the price of the magnesium potassium sulfate fertilizer is about 2100 yuan/ton, and the total income of the bittern per ton can be 237 yuan to 747 yuan.
Drawings
FIG. 1 is a flow chart of a method for preparing salt bittern from seawater and co-producing magnesium sulfate monohydrate and magnesium potassium sulfate fertilizer.
Detailed Description
The present invention will be further described by way of examples, which are not intended to limit the scope of the invention. Experimental methods, in which specific conditions are not specified in examples, are generally available commercially according to conventional conditions as well as those described in handbooks, or according to general-purpose equipment, materials, reagents, etc. used under conditions suggested by manufacturers, unless otherwise specified.
The method comprises the following specific steps:
example 1
Salt-making bittern from 1 ton of sea water and 24.22kg of Na 2 SO 4 Mixing and marinating; wherein the salt-making bittern contains 70g/L NaCl and 192g/L MgCl 2 KCl 38g/L and MgSO 54g/L 4 Added Na 2 SO 4 The mass is 2.4 percent of the mass of the bittern. Will be blended with Na 2 SO 4 Pumping the obtained bittern into a single-effect evaporator for negative pressure evaporation, wherein the evaporation temperature is controlled to be 100 ℃, and the relative bittern evaporation water loss rate is 59.4%; carrying out solid-liquid separation on the mother solution discharged from the evaporator to obtain mixed salt of Kie and NaCl with the mass fraction of Kie of 50.3% and mother solution for extracting the Kie; the magnesium sulfate monohydrate product is obtained by carrying out sedimentation centrifugal separation, fresh water washing and drying on mixed salt of the Kie and NaCl with the mass fraction of 50.3%, wherein the mass fraction of Mg in the magnesium sulfate monohydrate product is 16.2% and the mass fraction of Cl is 1.0%, so that the first grade product requirement in the industrial magnesium sulfate standard of HGT 2680-2017 is met.
Cooling the high temperature Kie extraction mother liquor to 75 ℃ and adding Na with the mass of 7.6% of the mass of the Kie extraction mother liquor 2 SO 4 Crystallizing, and further carrying out solid-liquid separation to obtain Lan and NaCl mixed salt containing 45.8% of Lan by mass fraction and Lan extracting mother liquor; adding KCl and Na with the mass of 1.55% and 5.22% of the mass of the Lan mother liquor into the Lan mother liquor 2 SO 4 Pumping the mixture into a single-effect evaporator for negative pressure evaporation after uniform mixing, controlling the evaporation temperature to be 75 ℃ and controlling the relative mother liquor evaporation water loss rate to be 8.65%; carrying out solid-liquid separation on the mother solution discharged from the evaporator to obtain Lan and NaCl mixed salt containing 54.7% of Lan by mass fraction and Lan-extracting circulating mother solution; adding KCl and Na with the mass of 1.55% and 5.22% of the mass of the Lan circulating mother liquor into the Lan circulating mother liquor 2 SO 4 After being uniformly mixed, the mixture returns to a single-effect evaporator with the evaporating temperature of 75 ℃ for continuous evaporation and extraction of Lan; the Lan and NaCl mixed salt obtained by cooling crystallization and evaporation is subjected to reverse flotation, fresh water washing and drying to obtain a potassium magnesium sulfate fertilizer product, wherein K is contained in the product 2 The mass fraction of O is 21.7%, the mass fraction of Mg is 11.2%, the mass fraction of S is 22.1%, the mass fraction of Cl is 2.6%, and the mass fraction of Na is 1.3%, thereby meeting the requirements of qualified products in GB/T20937-2007 potassium magnesium sulfate fertilizer standards. The recovery rate of K in bittern is 86%, the recovery rate of Mg is 88% and SO is the same in the whole process 4 2- The recovery rate of (2%) was 92%, and was higher than 80%.
Example 2
Directly pumping 1 ton of seawater salt-making bittern into an MVR evaporator for negative pressure evaporation; wherein the sea water salt-making bittern contains 144g/L NaCl and 117g/L MgCl 2 KCl 23g/L and MgSO 51g/L 4 The evaporation temperature is controlled to be 100 ℃, and the relative bittern evaporation water loss rate is 73.3%; carrying out solid-liquid separation on the mother solution discharged from the evaporator to obtain Kie and NaCl mixed salt containing 28.5% of Kie by mass and Kie extracting mother solution; the magnesium sulfate monohydrate product is obtained by carrying out sedimentation centrifugal separation, fresh water washing and drying on the mixed salt of the Kie and the NaCl with the mass fraction of 28.5%, wherein the mass fraction of Mg in the magnesium sulfate monohydrate product is 15.9% and the mass fraction of Cl is 1.3%, so that the first grade product requirement in the industrial magnesium sulfate standard of HGT 2680-2017 is met.
Cooling the high temperature Kie extraction mother liquor to 75 ℃ and adding Na with the mass of 6.0 percent and 4.9 percent of the mass of the Kie extraction mother liquor respectively 2 SO 4 Crystallizing with water, and further performing solid-liquid separation to obtain mixed salt of Lan and NaCl with Lan mass fraction of 41.7% and Lan extracting mother solution; adding KCl and Na with the mass of 0.93 percent and 3.29 percent of the mass of the Lan mother liquor into the Lan mother liquor 2 SO 4 Pumping the mixture into a single-effect evaporator for negative pressure evaporation after uniform mixing, controlling the evaporation temperature to be 75 ℃ and controlling the relative mother liquor evaporation water loss rate to be 5.42%; carrying out solid-liquid separation on the mother solution discharged from the evaporator to obtain Lan and NaCl mixed salt containing 54.7% of Lan by mass fraction and Lan-extracting circulating mother solution; adding KCl and Na with the mass of 0.93 percent and 3.29 percent of the mass of the Lan circulating mother liquor into the Lan circulating mother liquor 2 SO 4 After being uniformly mixed, the mixture returns to a single-effect evaporator with the evaporating temperature of 75 ℃ for continuous evaporation and extraction of Lan; the Lan and NaCl mixed salt obtained by cooling crystallization and evaporation is subjected to reverse flotation, fresh water washing and drying to obtain a potassium magnesium sulfate fertilizer product, wherein K is contained in the product 2 The mass fraction of O is 21.9%, the mass fraction of Mg is 11.8%, the mass fraction of S is 22.4%, the mass fraction of Cl is 2.3%, and the mass fraction of Na is 1.1%, thereby meeting the requirements of qualified products in GB/T20937-2007 potassium magnesium sulfate fertilizer standards. The recovery rate of K in bittern is 82%, the recovery rate of Mg is 84% and SO is the same in the whole process 4 2- The recovery rate of (2) is 91%, and is higher than 80%.
The foregoing has described exemplary embodiments of the invention, it being understood that any simple variations, modifications, or other equivalent arrangements which would not unduly obscure the invention may be made by those skilled in the art without departing from the spirit of the invention.
Claims (9)
1. The method for preparing salt bittern from seawater and co-producing magnesium sulfate monohydrate and magnesium potassium sulfate fertilizer is characterized by comprising the following steps of:
(1) Adding Na into salt-making bittern from sea water 2 SO 4 And MgCl 2 Mixing the solids and adding brine to obtain first mixed brine;
(2) Adding the first mixed brine into a high-temperature evaporator for evaporation and salt precipitation; the evaporation temperature is 90-130 ℃;
(3) Carrying out solid-liquid separation on the materials discharged by the high-temperature evaporator to obtain mixed salt containing magnesium sulfate monohydrate Kie and NaCl and Kie extracting mother liquor;
(4) Separating, washing and drying the mixed salt containing Kie and NaCl obtained by solid-liquid separation in the step (3) to obtain the magnesium sulfate monohydrate MgSO 4 ·H 2 An O product;
(5) The Kie extracting mother liquor is cooled to the temperature of 60 ℃ to 85 ℃ in a constant temperature crystallizer, and Na is added at the same time 2 SO 4 And water for conversion;
(6) Carrying out solid-liquid separation on the material liquid discharged from the crystallizer to obtain mixed salt containing anhydrous kainite Lan and NaCl and Lan extracting mother liquor;
(7) The Lan mother liquor is extracted with KCl and Na 2 SO 4 Mixing, adding into a low-temperature evaporator for evaporation and salt precipitation, wherein the evaporation temperature is 60-85 ℃;
(8) Carrying out solid-liquid separation on the materials discharged by the low-temperature evaporator to obtain mixed salt containing anhydrous kainite Lan and NaCl and a circulating mother solution for Lan extraction;
(9) The Lan circulating mother liquor is extracted with KCl and Na 2 SO 4 Mixing and then entering a low-temperature evaporator for circulation;
(10) And (3) carrying out solid-liquid separation on materials discharged from the constant temperature crystallizer and the low temperature evaporator to obtain mixed salt containing anhydrous kainite Lan and NaCl, and separating, washing and drying to obtain a potash magnesium sulphate fertilizer product.
2. The process according to claim 1, wherein in step (1), the seawater salt brine contains 50g/L to 200g/L NaCl and 100g/L to 210g/L MgCl 2 15g/L-45g/L KCl and 40g/L-120g/L MgSO 4 。
3. The method according to claim 1, wherein in step (1), na is added 2 SO 4 The mass is 0-15% of the mass of the bittern, and MgCl is added 2 The mass is 0% of the mass of the bittern-15％。
4. The method of claim 1, wherein in step (2) the relative bittern steaming water loss rate is 45% -85%.
5. The method of claim 1, wherein in step (3), magnesium sulfate monohydrate Kie is MgSO 4 ·H 2 O; in the step (6), the anhydrous kainite Lan is K 2 SO 4 ·2MgSO 4 。
6. The method according to claim 1, wherein in step (5), na is added 2 SO 4 The mass of the water is 0-15% of the mass of the Kie extracting mother liquor, and the mass of the water is 0-10% of the mass of the Kie extracting mother liquor.
7. The method according to claim 1, wherein in the step (7), KCl is added in an amount of 0 to 10% by mass of the Lan mother liquor, and Na is added 2 SO 4 The mass of the mother solution is 0-15% of that of the Lan extraction mother solution, and the relative evaporation rate of the mother solution is 2.5-15%.
8. The method according to claim 1, wherein in the step (9), KCl is added in an amount of 0 to 10% by mass of the Lan-extracting circulating mother liquor, and Na is added 2 SO 4 The mass of the mother solution is 0-15% of the mass of the Lan circulating mother solution.
9. The method according to claim 1, wherein in the step (10), the potassium magnesium sulfate fertilizer product is obtained by reverse flotation, water washing and drying of a mixed salt containing anhydrous kainite Lan and NaCl.
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