CN115010161A - Method for converting waste gypsum into alpha semi-hydrated gypsum - Google Patents
Method for converting waste gypsum into alpha semi-hydrated gypsum Download PDFInfo
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- CN115010161A CN115010161A CN202210058243.5A CN202210058243A CN115010161A CN 115010161 A CN115010161 A CN 115010161A CN 202210058243 A CN202210058243 A CN 202210058243A CN 115010161 A CN115010161 A CN 115010161A
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- 229910052602 gypsum Inorganic materials 0.000 title claims abstract description 42
- 239000010440 gypsum Substances 0.000 title claims abstract description 42
- 238000000034 method Methods 0.000 title claims abstract description 29
- 239000002699 waste material Substances 0.000 title claims abstract description 27
- 239000000243 solution Substances 0.000 claims abstract description 50
- 238000006243 chemical reaction Methods 0.000 claims abstract description 34
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 27
- 239000013078 crystal Substances 0.000 claims abstract description 27
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims abstract description 22
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims abstract description 20
- 239000002253 acid Substances 0.000 claims abstract description 16
- 239000012266 salt solution Substances 0.000 claims abstract description 16
- 159000000007 calcium salts Chemical class 0.000 claims abstract description 15
- 239000007788 liquid Substances 0.000 claims abstract description 15
- 239000000920 calcium hydroxide Substances 0.000 claims abstract description 14
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims abstract description 14
- 239000002893 slag Substances 0.000 claims abstract description 12
- 238000000926 separation method Methods 0.000 claims abstract description 9
- 239000000126 substance Substances 0.000 claims abstract description 9
- 238000003756 stirring Methods 0.000 claims abstract description 6
- 239000007864 aqueous solution Substances 0.000 claims abstract description 5
- ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical compound O.[Ca+2].[Ca+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZOMBKNNSYQHRCA-UHFFFAOYSA-J 0.000 claims description 27
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 18
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 18
- 229960001760 dimethyl sulfoxide Drugs 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 239000003513 alkali Substances 0.000 claims description 9
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 claims description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 8
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 8
- 239000012670 alkaline solution Substances 0.000 claims description 8
- 229910001424 calcium ion Inorganic materials 0.000 claims description 8
- 239000001509 sodium citrate Substances 0.000 claims description 8
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 claims description 8
- 235000011083 sodium citrates Nutrition 0.000 claims description 8
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 6
- 238000005904 alkaline hydrolysis reaction Methods 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 4
- 238000001914 filtration Methods 0.000 claims description 4
- 150000007524 organic acids Chemical group 0.000 claims description 4
- 239000005416 organic matter Substances 0.000 claims description 4
- KDYFGRWQOYBRFD-UHFFFAOYSA-N succinic acid Chemical compound OC(=O)CCC(O)=O KDYFGRWQOYBRFD-UHFFFAOYSA-N 0.000 claims description 4
- 150000003462 sulfoxides Chemical group 0.000 claims description 4
- FYSNRJHAOHDILO-UHFFFAOYSA-N thionyl chloride Chemical compound ClS(Cl)=O FYSNRJHAOHDILO-UHFFFAOYSA-N 0.000 claims description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 3
- 229910017604 nitric acid Inorganic materials 0.000 claims description 3
- BJEPYKJPYRNKOW-REOHCLBHSA-N (S)-malic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O BJEPYKJPYRNKOW-REOHCLBHSA-N 0.000 claims description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 2
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 claims description 2
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 claims description 2
- BJEPYKJPYRNKOW-UHFFFAOYSA-N alpha-hydroxysuccinic acid Natural products OC(=O)C(O)CC(O)=O BJEPYKJPYRNKOW-UHFFFAOYSA-N 0.000 claims description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 2
- 239000002585 base Substances 0.000 claims description 2
- 235000015165 citric acid Nutrition 0.000 claims description 2
- 238000000354 decomposition reaction Methods 0.000 claims description 2
- CCAFPWNGIUBUSD-UHFFFAOYSA-N diethyl sulfoxide Chemical compound CCS(=O)CC CCAFPWNGIUBUSD-UHFFFAOYSA-N 0.000 claims description 2
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 claims description 2
- 239000000347 magnesium hydroxide Substances 0.000 claims description 2
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims description 2
- 239000001630 malic acid Substances 0.000 claims description 2
- 235000011090 malic acid Nutrition 0.000 claims description 2
- 239000001384 succinic acid Substances 0.000 claims description 2
- 235000011044 succinic acid Nutrition 0.000 claims description 2
- 239000011975 tartaric acid Substances 0.000 claims description 2
- 235000002906 tartaric acid Nutrition 0.000 claims description 2
- 238000005265 energy consumption Methods 0.000 abstract description 4
- 230000035484 reaction time Effects 0.000 abstract description 3
- PASHVRUKOFIRIK-UHFFFAOYSA-L calcium sulfate dihydrate Chemical compound O.O.[Ca+2].[O-]S([O-])(=O)=O PASHVRUKOFIRIK-UHFFFAOYSA-L 0.000 description 11
- 239000012452 mother liquor Substances 0.000 description 11
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 8
- 229910052938 sodium sulfate Inorganic materials 0.000 description 8
- 235000011152 sodium sulphate Nutrition 0.000 description 8
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- 238000006477 desulfuration reaction Methods 0.000 description 5
- 230000023556 desulfurization Effects 0.000 description 5
- 239000003546 flue gas Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 230000009466 transformation Effects 0.000 description 5
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 4
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 description 4
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical group [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000010025 steaming Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- -1 fluorgypsum Chemical compound 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000010413 mother solution Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 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
- 239000002994 raw material Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 238000012876 topography Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/46—Sulfates
- C01F11/466—Conversion of one form of calcium sulfate to another
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/46—Sulfates
- C01F11/468—Purification of calcium sulfates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
-
- 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
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention discloses a method for converting waste gypsum into alpha semi-hydrated gypsum, which comprises the steps of decomposing the waste gypsum by using strong base, carrying out solid-liquid separation to obtain sulfate solution and calcium hydroxide slag, carrying out acidolysis on the calcium hydroxide slag by using strong acid, carrying out solid-liquid separation to obtain calcium salt solution and acid insoluble substances, adding the sulfate solution and the calcium salt solution into aqueous solution containing a crystal phase conversion agent and a crystal appearance guiding agent, controlling conditions such as temperature, stirring strength and the like, and quickly preparing the semi-hydrated gypsum; the method realizes the reclamation of the waste gypsum, and has the characteristics of short reaction time, low energy consumption, simple method and low cost for preparing products with high added value.
Description
Technical Field
The invention provides a method for preparing alpha hemihydrate gypsum, belongs to the field of waste gypsum resource utilization, and is used for preparing a high value-added product.
Background
The waste gypsum has various types, large production capacity and great influence on the environment, such as phosphogypsum, fluorgypsum, flue gas desulfurization gypsum and the like. Taking phosphogypsum as an example: phosphogypsum is an industrial solid byproduct generated in the process of producing phosphoric acid by a wet method, about 7000 million tons are generated in China every year, and the phosphogypsum is the largest solid waste of discharge and stockpiling quantity in China at present. The phosphogypsum has wide application, is used for manufacturing chemical products, building material raw materials and products, modified soil, filling materials and the like, and has the comprehensive utilization rate of only 40 percent. The utilization rate is low, and the main reason is that the phosphogypsum contains a plurality of impurity types, and the resource utilization lacks a low-cost mature technology. The composition of the fluorgypsum and the flue gas desulfurization gypsum is similar to that of the phosphogypsum.
The preparation of high-additional products from waste gypsum is the best choice for eliminating the environmental pollution and changing waste into valuables, and the current main flow direction is to prepare alpha hemihydrate gypsum. The common methods comprise a pressure steaming method, a pressurized water solution method and a normal pressure water solution method, wherein the pressure steaming method comprises the steps of putting waste gypsum into a still kettle, introducing saturated steam and raising the temperature, the pressurized water solution method comprises the steps of putting the waste gypsum into a pressurized container and mixing the waste gypsum and water into slurry, the two methods have high energy consumption, the prepared semi-hydrated gypsum is not regular enough, the compressive strength and the flexural strength are general and are not ideal, the normal pressure salt solution method has long reaction time and poor crystal transformation effect, industrial transformation cannot be realized, and the three methods have the defects of low energy consumption, poor crystal transformation effect and the like. In addition, the crystal phase transformation agent plays a key role in the process of preparing the alpha hemihydrate gypsum, and the reported crystal phase transformation agents comprise water and alcohols, and other types are rare. The preparation of high value-added products from waste gypsum faces technical bottlenecks, and a new method for preparing semi-hydrated gypsum with low energy consumption is urgently needed.
Disclosure of Invention
The invention provides a method for quickly converting waste gypsum into alpha semi-hydrated gypsum, which comprises the steps of quickly decomposing the waste gypsum by using strong alkali to extract sulfur, hydrolyzing calcium hydroxide slag by using strong acid to extract calcium, preparing reaction mother liquor for converting the alpha semi-hydrated gypsum in advance, adding extracted sulfate ion-containing solution and calcium salt solution, and mixing and contacting to quickly prepare the alpha semi-hydrated gypsum.
The technical scheme of the invention is as follows:
decomposing waste gypsum by using strong base, performing solid-liquid separation to obtain sulfate solution and calcium hydroxide slag, performing solid-liquid separation to obtain calcium salt solution and acid insoluble substances, adding the sulfate solution and the calcium salt solution into an aqueous solution (reaction mother solution) containing a crystal phase conversion agent and a crystal appearance directing agent, reacting at 70-140 ℃ under stirring, controlling the temperature, the stirring strength and other factors, quickly preparing alpha hemihydrate gypsum, and controlling the length-diameter ratio of crystals by adjusting reaction conditions.
The crystal phase conversion agent is a sulfoxide organic matter, and the crystal appearance guiding agent is an organic acid.
The sulfoxide organic matter is one or more of methyl sulfoxide, dimethyl sulfoxide, thionyl chloride and diethyl sulfoxide, and the organic acid is one or more of citric acid, sodium citrate, tartaric acid, malic acid and succinic acid.
The method comprises the following specific steps:
(1) according to the liquid-solid ratio (mL: g) of 4-20, feeding the waste gypsum into an alkaline hydrolysis device filled with an alkaline solution, decomposing the waste gypsum by using the alkaline solution, wherein the alkaline solution is one or more of a sodium hydroxide solution, a potassium hydroxide solution, an ammonia water solution and a magnesium hydroxide solution, adding 1.0-1.5 times of alkali in the alkaline solution according to the theoretical alkali consumption, and filtering after decomposition to obtain a sulfate solution and calcium hydroxide residues;
(2) conveying the calcium hydroxide slag into an acidolysis device containing an acid solution according to the liquid-solid ratio (mL: g) of 5-10, carrying out acidolysis on the calcium hydroxide slag by using the acid solution, wherein the acid solution is one or more of hydrochloric acid, nitric acid and hydrofluoric acid with the mass concentration of 5-35%, and filtering after the acidolysis is finished to obtain a calcium salt solution and an acid insoluble substance;
(3) adding sulfate solution and calcium salt solution into aqueous solution containing crystal phase conversion agent and crystal appearance directing agent, wherein the crystal appearance directing agent is added in SO 4 2- 0.01-10% of the content, 1-99% of the volume ratio of the crystal phase conversion agent to water, and then stirring and reacting at 70-140 ℃ for 5-80 min to prepare the alpha hemihydrate gypsum;
in the step (3), the sulfate solution and the calcium salt solution are added in a manner that the molar weight of the sulfate ions is equal to that of the calcium ions. The working principle of the invention is as follows:
the main component of the waste gypsum is calcium sulfate, phosphogypsum is decomposed by strong alkali and is converted into calcium hydroxide with lower solubility, and strong acid and the calcium hydroxide are subjected to neutralization reaction. Containing sulfate radical ionContacting the seed solution with a calcium salt solution, the sulfate ion-containing solution containing SO 4 2- And calcium salt solution containing Ca 2+ The method is a main component for preparing the gypsum, sulfate radicals and calcium ions are in contact reaction to generate calcium sulfate dihydrate with extremely low solubility under the condition of not changing the reaction atmosphere, and the reaction atmosphere needs to be changed when the sulfate radicals and the calcium ions are in contact reaction to generate the alpha hemihydrate gypsum. The prepared reaction mother liquor aims at improving the reaction temperature, adding a morphology directing agent and the like, and then controlling the factors such as nucleation supersaturation degree and the like to create an environment beneficial to the growth of the alpha hemihydrate gypsum.
The method has the following advantages:
the method for preparing the alpha hemihydrate gypsum is different from other conventional methods, sulfate ions and calcium ions are directly contacted and converted into the alpha hemihydrate gypsum, the conventional method for preparing the hemihydrate gypsum is broken, and the reaction time is extremely short due to rapid crystal conversion, so that alpha hemihydrate gypsum crystals are generated.
Drawings
FIG. 1 is a schematic flow diagram of a process for preparing hemihydrate gypsum according to the present invention;
FIG. 2 is a topographical view of hemihydrate gypsum prepared in example 1 of the present invention;
FIG. 3 is a topographical view of hemihydrate gypsum prepared in example 2 of the present invention;
FIG. 4 is a topographical view of hemihydrate gypsum prepared in example 3 of the present invention.
Detailed Description
The invention is explained in more detail below with reference to the figures and examples, without limiting the scope of the invention.
Example 1: as shown in figure 1, taking 20t of phosphogypsum, preparing NaOH solution according to 1.2 times of theoretical alkali consumption, feeding the phosphogypsum into an alkaline hydrolysis device filled with the NaOH solution according to the solid-to-liquid ratio g: mL of 1:4 to decompose the phosphogypsum, carrying out solid-liquid separation to obtain sodium sulfate solution and calcium hydroxide slag, taking 6t of calcium hydroxide slag, preparing hydrochloric acid solution with the mass concentration of 15% to carry out acidolysis on the calcium hydroxide slag to obtain calcium chloride solution and acid-insoluble substances, wherein the solid-to-liquid ratio g: mL is 1: 7; preparing reaction mother liquor, using dimethyl sulfoxide as crystal phase conversion agent, using sodium citrate as morphology directing agent, adding sodium citrate in SO in sodium sulfate solution 4 2- 0.01 percent of the content, 30 percent of volume ratio of dimethyl sulfoxide to water, heating the reaction mother liquor to 95 ℃, rotating at 150rpm, adding a sodium sulfate solution and a calcium chloride solution into the reaction mother liquor according to the equal molar weight ratio of sulfate ions to calcium ions, reacting for 15min, and carrying out contact reaction to generate alpha hemihydrate gypsum, wherein the topography of the hemihydrate gypsum is shown in figure 2.
Example 2: taking 20t of fluorgypsum, preparing a KOH solution according to 1.4 times of theoretical alkali consumption, feeding the fluorgypsum into an alkaline hydrolysis device filled with the KOH solution according to a solid-liquid ratio g: mL of 1:5, decomposing the fluorgypsum, carrying out solid-liquid separation to obtain a potassium sulfate solution and calcium hydroxide residues, taking 5t of the calcium hydroxide residues, preparing a hydrochloric acid solution with a mass concentration of 10%, and carrying out acidolysis on the calcium hydroxide residues to obtain a calcium chloride solution and an acid insoluble substance, wherein the solid-liquid ratio g: mL is 1: 8; preparing reaction mother liquor, using dimethyl sulfoxide as crystal phase conversion agent, using sodium citrate as morphology guide agent, the volume ratio of dimethyl sulfoxide and water is 40%, and the addition quantity of sodium citrate is SO in sodium sulfate solution 4 2- 0.05 percent of the content, heating the reaction mother liquor to 94 ℃, rotating at the speed of 200rpm, adding a sodium sulfate solution and a calcium chloride solution into the reaction mother liquor according to the equal molar weight ratio of sulfate ions to calcium ions, reacting for 20min, carrying out contact reaction to generate the hemihydrate gypsum, wherein the appearance graph of the alpha hemihydrate gypsum is shown in figure 3.
Example 3: taking 15t of flue gas desulfurization gypsum, preparing NaOH solution according to 1.3 times of theoretical alkali consumption, feeding the flue gas desulfurization gypsum into an alkaline hydrolysis device filled with the NaOH solution according to the solid-liquid ratio g: mL of 1:6 to decompose the flue gas desulfurization gypsum, carrying out solid-liquid separation to obtain sodium sulfate solution and calcium hydroxide residue, taking 7t of calcium hydroxide residue, preparing nitric acid solution with the mass concentration of 15% to carry out acidolysis on the calcium hydroxide residue to obtain calcium nitrate solution and acid insoluble substances, wherein the solid-liquid ratio g: mL of 1: 6; preparing reaction mother liquor, using dimethyl sulfoxide as crystal phase conversion agent, using sodium citrate as morphology guide agent, the volume ratio of dimethyl sulfoxide and water is 80%, and the addition quantity of sodium citrate is SO in sodium sulfate solution 4 2- 0.05 percent of the content, heating the reaction mother liquor to 96 ℃, rotating at the speed of 250rpm, adding a sodium sulfate solution and a calcium nitrate solution into the reaction mother liquor according to the equal molar weight proportion of sulfate ions and calcium ions, and reactingIn the time of 10min, the contact reaction generates the hemihydrate gypsum, and the shape graph of the alpha hemihydrate gypsum is shown in figure 4.
Claims (5)
1. A method for converting waste gypsum into alpha hemihydrate gypsum is characterized by comprising the following steps: decomposing waste gypsum by using strong base, performing solid-liquid separation to obtain sulfate solution and calcium hydroxide slag, performing solid-liquid separation to obtain calcium salt solution and acid insoluble substances, adding the sulfate solution and the calcium salt solution into an aqueous solution containing a crystal phase conversion agent and a crystal appearance guiding agent, and reacting at 70-140 ℃ under stirring to obtain the alpha semi-hydrated gypsum.
2. The process of converting waste gypsum to alpha hemihydrate gypsum of claim 1, wherein: the crystal phase conversion agent is a sulfoxide organic matter, and the crystal appearance guiding agent is organic acid.
3. The process of converting waste gypsum to alpha hemihydrate gypsum of claim 2, wherein: the sulfoxide organic matter is one or more of methyl sulfoxide, dimethyl sulfoxide, thionyl chloride and diethyl sulfoxide, and the organic acid is one or more of citric acid, sodium citrate, tartaric acid, malic acid and succinic acid.
4. The method for converting waste gypsum into alpha hemihydrate gypsum according to claim 3, comprising the following steps:
(1) according to the liquid-solid ratio (mL: g) of 4-20, feeding the waste gypsum into an alkaline hydrolysis device filled with an alkaline solution, decomposing the waste gypsum by using the alkaline solution, wherein the alkaline solution is one or more of a sodium hydroxide solution, a potassium hydroxide solution, an ammonia water solution and a magnesium hydroxide solution, adding 1.0-1.5 times of alkali in the alkaline solution according to the theoretical alkali consumption, and filtering after decomposition to obtain a sulfate solution and calcium hydroxide residues;
(2) conveying the calcium hydroxide slag into an acidolysis device containing an acid solution according to the liquid-solid ratio (mL: g) of 5-10, carrying out acidolysis on the calcium hydroxide slag by using the acid solution, wherein the acid solution is one or more of hydrochloric acid, nitric acid and hydrofluoric acid with the mass concentration of 5-35%, and filtering after the acidolysis is finished to obtain a calcium salt solution and an acid insoluble substance;
(3) adding sulfate solution and calcium salt solution into aqueous solution containing crystal phase conversion agent and crystal appearance directing agent, wherein the crystal appearance directing agent is added in SO 4 2- 0.01-10% of the content, and 1-99% of the volume ratio of the crystalline phase conversion agent to water, and then stirring and reacting at 70-140 ℃ for 5-80 min to prepare the alpha hemihydrate gypsum.
5. The process of converting waste gypsum to alpha hemihydrate gypsum of claim 4, wherein: in the step (3), the sulfate solution and the calcium salt solution are added in a manner that the molar weight of the sulfate ions is equal to that of the calcium ions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210058243.5A CN115010161B (en) | 2022-01-19 | 2022-01-19 | Method for converting waste gypsum into alpha semi-hydrated gypsum |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210058243.5A CN115010161B (en) | 2022-01-19 | 2022-01-19 | Method for converting waste gypsum into alpha semi-hydrated gypsum |
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| Publication Number | Publication Date |
|---|---|
| CN115010161A true CN115010161A (en) | 2022-09-06 |
| CN115010161B CN115010161B (en) | 2024-01-05 |
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| CN116553848A (en) * | 2023-03-14 | 2023-08-08 | 云南省生态环境科学研究院 | Method for preparing alpha high-strength gypsum by semi-in-situ crystal transformation |
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