CN116553848A - Method for preparing alpha high-strength gypsum by semi-in-situ crystal transformation - Google Patents
Method for preparing alpha high-strength gypsum by semi-in-situ crystal transformation Download PDFInfo
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- phosphogypsum
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- 239000013078 crystal Substances 0.000 title claims abstract description 85
- 238000000034 method Methods 0.000 title claims abstract description 84
- 229910052602 gypsum Inorganic materials 0.000 title claims abstract description 83
- 239000010440 gypsum Substances 0.000 title claims abstract description 83
- 230000009466 transformation Effects 0.000 title claims abstract description 61
- 238000011065 in-situ storage Methods 0.000 title claims abstract description 19
- 239000007788 liquid Substances 0.000 claims abstract description 104
- PASHVRUKOFIRIK-UHFFFAOYSA-L calcium sulfate dihydrate Chemical compound O.O.[Ca+2].[O-]S([O-])(=O)=O PASHVRUKOFIRIK-UHFFFAOYSA-L 0.000 claims abstract description 102
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 40
- 239000007787 solid Substances 0.000 claims abstract description 40
- 230000008569 process Effects 0.000 claims abstract description 37
- 238000000926 separation method Methods 0.000 claims abstract description 34
- 239000012535 impurity Substances 0.000 claims abstract description 33
- 239000000126 substance Substances 0.000 claims abstract description 30
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 28
- 238000002156 mixing Methods 0.000 claims abstract description 26
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 23
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 18
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 12
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 12
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 9
- 239000002002 slurry Substances 0.000 claims description 9
- 238000004062 sedimentation Methods 0.000 claims description 6
- VSGNNIFQASZAOI-UHFFFAOYSA-L calcium acetate Chemical compound [Ca+2].CC([O-])=O.CC([O-])=O VSGNNIFQASZAOI-UHFFFAOYSA-L 0.000 claims description 5
- 239000001639 calcium acetate Substances 0.000 claims description 5
- 235000011092 calcium acetate Nutrition 0.000 claims description 5
- 229960005147 calcium acetate Drugs 0.000 claims description 5
- USFZMSVCRYTOJT-UHFFFAOYSA-N Ammonium acetate Chemical compound N.CC(O)=O USFZMSVCRYTOJT-UHFFFAOYSA-N 0.000 claims description 4
- 239000005695 Ammonium acetate Substances 0.000 claims description 4
- 229940043376 ammonium acetate Drugs 0.000 claims description 4
- 235000019257 ammonium acetate Nutrition 0.000 claims description 4
- 229960000583 acetic acid Drugs 0.000 claims description 3
- 235000011054 acetic acid Nutrition 0.000 claims description 3
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 3
- 239000000920 calcium hydroxide Substances 0.000 claims description 3
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 3
- 229960004106 citric acid Drugs 0.000 claims description 3
- 235000015165 citric acid Nutrition 0.000 claims description 3
- UEGPKNKPLBYCNK-UHFFFAOYSA-L magnesium acetate Chemical compound [Mg+2].CC([O-])=O.CC([O-])=O UEGPKNKPLBYCNK-UHFFFAOYSA-L 0.000 claims description 3
- 239000011654 magnesium acetate Substances 0.000 claims description 3
- 229940069446 magnesium acetate Drugs 0.000 claims description 3
- 235000011285 magnesium acetate Nutrition 0.000 claims description 3
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 claims description 3
- 239000000347 magnesium hydroxide Substances 0.000 claims description 3
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims description 3
- 230000001131 transforming effect Effects 0.000 claims description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims 2
- 229910021529 ammonia Inorganic materials 0.000 claims 1
- 239000002994 raw material Substances 0.000 abstract description 8
- 238000002360 preparation method Methods 0.000 abstract description 7
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 abstract description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 abstract description 5
- 229910001424 calcium ion Inorganic materials 0.000 abstract description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 abstract description 4
- 239000002253 acid Substances 0.000 abstract description 3
- 238000010438 heat treatment Methods 0.000 description 28
- 238000004519 manufacturing process Methods 0.000 description 14
- 238000001027 hydrothermal synthesis Methods 0.000 description 8
- 238000001035 drying Methods 0.000 description 7
- 239000000843 powder Substances 0.000 description 7
- 238000011084 recovery Methods 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 238000010025 steaming Methods 0.000 description 6
- 238000009413 insulation Methods 0.000 description 5
- 238000010992 reflux Methods 0.000 description 5
- 238000005265 energy consumption Methods 0.000 description 4
- 239000004794 expanded polystyrene Substances 0.000 description 4
- 238000003825 pressing Methods 0.000 description 4
- 239000010453 quartz Substances 0.000 description 4
- 230000035484 reaction time Effects 0.000 description 4
- 239000000523 sample Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 3
- 229920000049 Carbon (fiber) Polymers 0.000 description 3
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 3
- 239000005751 Copper oxide Substances 0.000 description 3
- 235000011114 ammonium hydroxide Nutrition 0.000 description 3
- 239000004917 carbon fiber Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 229910000431 copper oxide Inorganic materials 0.000 description 3
- 150000004683 dihydrates Chemical class 0.000 description 3
- 230000005484 gravity Effects 0.000 description 3
- 238000009776 industrial production Methods 0.000 description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 3
- -1 polytetrafluoroethylene Polymers 0.000 description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 239000012266 salt solution Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000005187 foaming Methods 0.000 description 2
- 239000011490 mineral wool Substances 0.000 description 2
- 229920002635 polyurethane Polymers 0.000 description 2
- 239000004814 polyurethane Substances 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- RPAJSBKBKSSMLJ-DFWYDOINSA-N (2s)-2-aminopentanedioic acid;hydrochloride Chemical class Cl.OC(=O)[C@@H](N)CCC(O)=O RPAJSBKBKSSMLJ-DFWYDOINSA-N 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 230000006978 adaptation Effects 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
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Inorganic materials [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 1
- 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 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 229920006389 polyphenyl polymer Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B11/00—Calcium sulfate cements
- C04B11/26—Calcium sulfate cements strating from chemical gypsum; starting from phosphogypsum or from waste, e.g. purification products of smoke
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B11/00—Calcium sulfate cements
- C04B11/02—Methods and apparatus for dehydrating gypsum
- C04B11/024—Ingredients added before, or during, the calcining process, e.g. calcination modifiers
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B11/00—Calcium sulfate cements
- C04B11/02—Methods and apparatus for dehydrating gypsum
- C04B11/028—Devices therefor characterised by the type of calcining devices used therefor or by the type of hemihydrate obtained
- C04B11/032—Devices therefor characterised by the type of calcining devices used therefor or by the type of hemihydrate obtained for the wet process, e.g. dehydrating in solution or under saturated vapour conditions, i.e. to obtain alpha-hemihydrate
-
- 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)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention provides a method for preparing alpha high-strength gypsum by semi-in-situ crystal transformation, which comprises the steps of mixing acid phosphogypsum reslurry with alkaline substances for neutralization in the delivery process of delivery from a factory, and obtaining first liquid containing a large amount of calcium ions and sulfate ions and first solid through first solid-liquid separation; mixing the first solid with hydrochloric acid, sequentially performing impurity removal treatment and second solid-liquid separation to obtain second liquid containing calcium ions, sulfate ions and chloride ions and impurity second solid, mixing the first liquid, the second liquid and a crystal transformation agent, and performing crystal transformation to obtain alpha high-strength gypsum. The method provided by the invention uses phosphogypsum as a raw material to produce alpha high-strength gypsum in the process of shipping and conveying phosphogypsum reslurry, so that the preparation cost is obviously reduced, the semi-in-situ crystal transformation of phosphogypsum is realized, and the process flow is simplified.
Description
Technical Field
The invention relates to the technical field of gypsum materials, in particular to a method for preparing alpha high-strength gypsum by semi-in-situ crystal transformation.
Background
Phosphogypsum is a solid waste of calcium sulfate discharged in the process of producing phosphoric acid by wet method, and usually exists in the form of calcium sulfate dihydrate to produce 1 ton of P 2 O 5 About 4.5 to 5.5 tons of phosphogypsum are discharged. Compared with natural gypsum, phosphogypsum generally contains components such as phosphorus, fluorine, organic matters and the like, which affect the service performance and increase the utilization cost, and the piling treatment is mainly adopted at present.
The existing high-strength gypsum preparation method mainly comprises a steam pressurizing method and a pressurizing water solution method or a method of crystallizing in certain salt solutions to form normal-pressure salt solution. Steam pressurizing is the earliest method used for the industrial production of high strength gypsum. The equipment used in the steam pressurizing method is generally a horizontal autoclave and a vertical autoclave, the horizontal autoclave is used for steaming and drying in different equipment, and a drying kiln is needed to be additionally built. The vertical autoclave directly lets in the superheated air to dry in the cauldron after the steaming and pressing, guarantees to a certain extent that semi-hydrated gypsum can not hydrate into dihydrate gypsum. The steaming and pressing method has more than 30 production lines in China, and the Ningxia building material institute realizes steaming and drying integration on the basis of the common steaming and pressing method. The mature autoclaved production line mainly adopts a vertical autoclave, and specifically comprises the steps of placing blocky dihydrate gypsum in the autoclave, introducing supersaturated steam into the upper part of the autoclave, and discharging condensate water from the lower part of the autoclave. However, the disadvantages of the autoclaved method are also limited in wide application, the raw materials adopted by the autoclaved method are blocky gypsum, quality fluctuation of the prepared high-strength gypsum powder occurs in the process of steaming and pressing due to uneven temperature difference between the inside and the outside of the gypsum blocks, the quality of the high-strength gypsum powder is seriously affected due to uneven heating of upper, middle and lower calcined gypsum blocks in a kettle in the drying stage of the autoclaved method, and in addition, the instability of the quality is related to factors such as quick stacking density of gypsum, weather and the like during drying, so that the quality of the high-strength gypsum produced by adopting the process is not easy to control. And then, a part of crystal transformation agent is lost when condensed water is discharged, and the crystal growth of semi-hydrated gypsum is affected due to the uneven local temperature in the autoclave, so that the strength of the high-strength gypsum prepared by an autoclaved method is very low, and is generally about 25 MPa. The constant-temperature dehydration time of the high-strength gypsum prepared by the autoclaved method is generally maintained for about 6 hours, so that the energy consumption in the production process is relatively high, and the production period is long. The pressurized aqueous solution process has become the mainstream production process for preparing high strength gypsum since the 90 s. Research on the pressurized aqueous solution method is carried out abroad earlier, wherein Japanese Wu Yufa combines the technical advantages of a crystal transfer agent and a seed crystal; the BSH company of Germany also has the production capacity of a hydrothermal method production process of 2 ten thousand tons/year set. The Europe mainly adopts a Knauf process production line and a POLCAL process to prepare the high-strength gypsum by taking the desulfurized gypsum as a raw material. The mature production example in China is that the Shandong Jinxin introduces the Germany hydrothermal method production line to produce 2 ten thousand tons of high-strength gypsum powder annually, in addition, the Tai an Jie ordinary gypsum technology limited company also produces 1 ten thousand tons of production lines for producing the high-strength gypsum powder by using the desulfurized gypsum in 2013 years, and the production quality completely reaches the standard. The hydrothermal method equipment mainly comprises three main equipment, namely a reaction kettle (with a stirring device), a high-speed centrifugal machine and an evaporation dryer. The hydrothermal method adopts powdery gypsum as raw material, the solid-liquid ratio is generally controlled to be about 1:4, the temperature is controlled to be between 135 and 145 ℃ and the constant temperature is controlled for a certain time, so that 1.5 crystal water of the dihydrate gypsum is removed to generate alpha-type hemihydrate gypsum, and the high-strength gypsum powder is obtained after centrifugation and drying. The alpha semi-hydrated gypsum is nucleated and grows in the liquid phase, so that the effect of the crystal transfer agent can be effectively exerted, and the short columnar alpha semi-hydrated gypsum crystal is prepared. Compared with the autoclaved method, the method has the advantages of less crystal defects, complete crystal growth and higher strength of products. However, the hydrothermal process is relatively complex in process flow compared with the steam pressurizing process, and the devices are connected by conveying equipment. The higher water-material ratio makes the energy consumption in the heating and drying process larger, and the effective utilization rate of energy is low. The hydrothermal method requires that the stirring device of the autoclave has good sealing property and production safety. Therefore, the traditional hydrothermal method has high production line investment and high energy consumption, and is limited to be widely applied to industrial production. The method has the advantages that the scholars continue to intensively study in the aspect of a hydrothermal method, duan Zhenhua takes the desulfurized gypsum as a raw material, the influence of technological parameters on alpha hemihydrate desulfurized gypsum is explored, and the result shows that the high-strength gypsum with the highest compressive strength of 49.4MPa of wet powder can be prepared by controlling the autoclaved temperature to 150 ℃ and the autoclaved time to 2-2.5 h, and the slurry concentration to 30-40%. Although the normal pressure conditions have reduced requirements for equipment, corrosion of the equipment by acid and chloride ions is almost unavoidable, resulting in serious economic losses. In recent years, many scholars have made many researches in this field, but the normal pressure salt solution method has not been reported in industrial production. Although the research on the method for preparing the alpha high-strength gypsum by the phosphogypsum is more and more, the popularization of the industrialized application of the phosphogypsum is limited due to the defects of high energy consumption, high cost, complex process and the like. Therefore, the method for preparing the alpha high-strength gypsum by using the phosphogypsum with low cost and simplified process is a problem to be solved in the prior art.
Disclosure of Invention
The invention aims to provide a method for preparing alpha high-strength gypsum by semi-in-situ crystal transformation, which takes phosphogypsum as a raw material to produce alpha high-strength gypsum in the process of phosphogypsum reslurry delivery, thereby remarkably reducing the preparation cost, realizing the semi-in-situ crystal transformation of phosphogypsum and simplifying the process flow.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a method for preparing alpha high-strength gypsum by semi-in-situ crystal transformation, which comprises the following steps:
(1) Mixing phosphogypsum reslurry with alkaline substances, and sequentially carrying out neutralization reaction and first solid-liquid separation to obtain first liquid and first solid;
(2) Mixing the first solid obtained in the step (1) with hydrochloric acid, and then sequentially carrying out impurity removal treatment and second solid-liquid separation to obtain second liquid and second solid;
(3) Mixing the first liquid obtained in the step (1), the second liquid obtained in the step (2) and a crystal transformation agent, and performing crystal transformation to obtain alpha high-strength gypsum;
the steps (1) - (3) are all carried out in the factory conveying process of phosphogypsum reslurry.
Preferably, the ratio of the mass of phosphogypsum in the phosphogypsum reslurry in the step (1) to the volume of the phosphogypsum reslurry is 1mg: (1.5-12) mL.
Preferably, the phosphogypsum re-slurry in the step (1) has a temperature of 70-90 ℃.
Preferably, the alkaline substance in the step (1) is at least one of sodium hydroxide, ammonia water, calcium hydroxide, potassium hydroxide and magnesium hydroxide.
Preferably, the mass of the alkaline substance in the step (1) is 0.5-8% of the mass of phosphogypsum in the phosphogypsum reslurry; the alkaline substance is added continuously in the delivery process of phosphogypsum reslurry.
Preferably, the first solid-liquid separation in the step (1) is natural sedimentation.
Preferably, the mass fraction of hydrochloric acid in the step (2) is 5% -20%; the ratio of the mass of the first solid to the volume of hydrochloric acid was 1mg: (5-10) mL.
Preferably, the crystal transforming agent in the step (3) is at least one of citric acid, acetic acid, calcium acetate, magnesium acetate and ammonium acetate; the mass of the crystal transfer agent is 0.1-5% of the total mass of the first liquid and the second liquid.
Preferably, the temperature of the crystallization in the step (3) is 90-110 ℃.
Preferably, the conveying pipeline used in the neutralization reaction in the step (1) and the conveying pipeline used in the impurity removal treatment in the step (2) are independently provided with heat insulation layers.
The invention provides a method for preparing alpha high-strength gypsum by semi-in-situ crystal transformation, which comprises the steps of mixing acid phosphogypsum reslurry with alkaline substances for neutralization in the delivery process of delivery from a factory, and obtaining first liquid containing a large amount of calcium ions and sulfate ions and first solid through first solid-liquid separation; mixing the first solid with hydrochloric acid, sequentially performing impurity removal treatment and second solid-liquid separation to obtain second liquid containing calcium ions, sulfate ions and chloride ions and impurity second solid, mixing the first liquid, the second liquid and a crystal transformation agent, and performing crystal transformation to obtain alpha high-strength gypsum. The method provided by the invention uses phosphogypsum as a raw material to produce alpha high-strength gypsum in the process of shipping and conveying phosphogypsum reslurry, so that the preparation cost is obviously reduced, the semi-in-situ crystal transformation of phosphogypsum is realized, and the process flow is simplified. The results of the examples show that the alpha high-strength gypsum prepared in the examples 1 to 3 of the present invention all show a short hexagonal prism-like shape, have good crystallinity, and are relatively uniform.
Drawings
FIG. 1 is a flow chart of preparing alpha high-strength gypsum by semi-in-situ crystallization in an embodiment of the invention;
FIG. 2 is a microstructure of the alpha high strength gypsum prepared in example 1 of the present invention;
FIG. 3 is a microstructure of the alpha high strength gypsum prepared in example 2 of the present invention;
FIG. 4 is a microstructure of the alpha high strength gypsum prepared in example 3 of the present invention.
Detailed Description
The invention provides a method for preparing alpha high-strength gypsum by semi-in-situ crystal transformation, which comprises the following steps:
(1) Mixing phosphogypsum reslurry with alkaline substances, and sequentially carrying out neutralization reaction and first solid-liquid separation to obtain first liquid and first solid;
(2) Mixing the first solid obtained in the step (1) with hydrochloric acid, and then sequentially carrying out impurity removal treatment and second solid-liquid separation to obtain second liquid and second solid;
(3) Mixing the first liquid obtained in the step (1), the second liquid obtained in the step (2) and a crystal transformation agent, and performing crystal transformation to obtain alpha high-strength gypsum;
the steps (1) - (3) are all carried out in the factory conveying process of phosphogypsum reslurry.
After phosphogypsum reslurry and alkaline substances are mixed, neutralization reaction and first solid-liquid separation are sequentially carried out, so that first liquid and first solid are obtained.
In the present invention, the ratio of the mass of phosphogypsum in the phosphogypsum reslurry to the volume of the phosphogypsum reslurry is preferably 1mg: (1.5-12) mL, more preferably 1mg: (2-10) mL. The invention controls the mass ratio of phosphogypsum and phosphogypsum reslurry in the range, so that phosphogypsum reslurry has higher flow property and ensures the smooth proceeding of delivery process.
In the present invention, the phosphogypsum re-slurry temperature is preferably 70 to 90 ℃. The invention controls the temperature of phosphogypsum reslurry in the above range to prevent phosphogypsum from solidifying, which is beneficial to pipeline transportation.
In the present invention, the alkaline substance is preferably at least one of sodium hydroxide, ammonia water, calcium hydroxide, potassium hydroxide and magnesium hydroxide. In the invention, the mass of the alkaline substance is preferably 0.5-8% of the mass of phosphogypsum in phosphogypsum reslurry; the alkaline substance is preferably added continuously during the delivery process of phosphogypsum reslurry. The invention controls the quality of alkaline matters in the above range, so as to be favorable for calcium sulfate dihydrate to generate alpha-semi-hydrated gypsum (namely alpha high-strength gypsum) under neutral and weak alkaline conditions, and the alkaline matters are utilized to strictly control the acid-base conditions.
In the present invention, the time of the neutralization reaction is preferably 1 to 3 hours. The invention controls the neutralization reaction time in the above range, so that the acidic substance and the alkaline substance of phosphogypsum are fully mixed.
In the present invention, the first solid-liquid separation means is preferably natural sedimentation.
After the first solid is obtained, the invention mixes the first solid with hydrochloric acid, and then sequentially carries out impurity removal treatment and second solid-liquid separation to obtain second liquid and second solid.
In the invention, the mass fraction of the hydrochloric acid is preferably 5% -20%; the ratio of the mass of the first solid to the volume of hydrochloric acid is preferably 1mg: (5-10) mL. The invention controls the mass ratio of the first solid and the hydrochloric acid in the above range so as to fully release calcium ions and sulfate ions in phosphogypsum, and simultaneously, the introduced chloride ions have positive influence on the recrystallization to generate alpha-hemihydrate gypsum.
In the present invention, the time of the impurity removal treatment is preferably 1 to 3 hours. The invention controls the time of impurity removal treatment in the range, and ensures the full dissolution of phosphogypsum and the release of impurities.
After the second solid is obtained, the second solid (mainly silica component) is preferably directly discharged or used as soil or the like.
After the first liquid and the second liquid are obtained, the invention mixes the first liquid, the second liquid and the crystal transfer agent, and then transfers crystals to obtain the alpha high-strength gypsum.
In the invention, the crystal transfer agent is preferably at least one of citric acid, acetic acid, calcium acetate, magnesium acetate and ammonium acetate; the mass of the crystal transfer agent is preferably 0.1% -5% of the total mass of the first liquid and the second liquid. The invention controls the quality of the crystal transfer agent in the above range, so as to utilize the calcium sulfate dihydrate in phosphogypsum to dissolve and recrystallize to generate alpha-hemihydrate gypsum, thereby improving the yield of the alpha-hemihydrate gypsum.
In the present invention, the temperature of the crystal transition is preferably 90 to 110 ℃. In the present invention, the time for the crystal transformation is preferably 1 to 3 hours. The invention controls the temperature and time of crystal transformation in the above range, and utilizes the calcium sulfate dihydrate in phosphogypsum to dissolve and recrystallize to generate alpha-semi-hydrated gypsum, thereby providing enough time and energy for the whole process.
After the crystal transformation is completed, the invention preferably carries out third solid-liquid separation on the crystal transformation product to obtain the alpha high-strength gypsum and the recovery liquid.
In the present invention, the recovery liquid is preferably refluxed as phosphogypsum reslurry.
In the invention, the technical scheme is carried out in the factory conveying process of phosphogypsum reslurry. In the present invention, the length of the conveying pipeline used in the neutralization reaction is preferably not less than 5m. In the invention, the length of the conveying pipeline used for the impurity removal treatment is preferably more than or equal to 5m. In the present invention, the transport pipe for the neutralization reaction and the transport pipe for the impurity removal treatment are preferably independently provided with heat insulating layers. In the invention, the material of the heat insulation layer is preferably one of an expanded polystyrene board (EPS board), an extruded polystyrene board (XPS board), rubber powder polyphenyl particle heat insulation slurry, polyurethane foaming material and rock wool board. In the present invention, the inner layer material of the conveying pipeline used in the neutralization and impurity removal treatment is preferably independently one of polytetrafluoroethylene, carbon fiber and copper oxide.
In the invention, the pipeline used for the crystal transformation is preferably a heating conveying pipeline. In the invention, the heating conveying pipeline is preferably a quartz heating plate coupled probe temperature sensor. In the invention, the length of the heating conveying pipeline is preferably more than or equal to 5m. In the present invention, the temperature raising conveying pipe is preferably provided with a temperature raising layer in its entire section. In the present invention, the inner layer material of the heating conveying pipe is preferably one of polytetrafluoroethylene, carbon fiber and copper oxide.
According to the method provided by the invention, the factory conveying pipeline of the original phosphogypsum reslurry is modified, so that phosphogypsum crystal transformation is realized, alpha high-strength gypsum is prepared by semi-in-situ phosphogypsum crystal transformation, the preparation process of the alpha high-strength gypsum is simplified, the preparation conditions and cost are reduced, the high added value recycling of waste gypsum is realized, the actual engineering application is facilitated, no secondary pollution is generated in the whole process, and the environmental protection risk is greatly reduced; the crystal transformation efficiency of the alpha high-strength gypsum is improved, the temperature of crystal transformation is reduced to below 110 ℃, high-pressure conditions are not needed, and a feasible route for high-added-value recycling of waste gypsum is provided; the method provided by the invention cooperatively operates the impurity removal treatment and crystal transformation, improves the quality of the alpha high-strength gypsum product, and finally obtains the third liquid which can be used in a reflux way, thereby realizing ecological cycle.
The technical solutions of the present invention will be clearly and completely described in the following in connection with the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Fig. 1 is a flow chart of preparing alpha high-strength gypsum by semi-in-situ crystal transformation in the embodiment of the invention, specifically:
an alkaline substance adding port is arranged at the factory position of phosphogypsum reslurry, the phosphogypsum reslurry and the alkaline substance which are acidic after factory delivery are mixed at the outlet position and then undergo a neutralization reaction, and a first liquid and a first solid are obtained through a first solid-liquid separation; mixing the first solid with hydrochloric acid, sequentially performing impurity removal treatment and second solid-liquid separation to obtain second liquid and impurity second solid, mixing the first liquid, the second liquid and a crystal conversion agent, sequentially performing crystal conversion and third solid-liquid separation to obtain alpha high-strength gypsum and a recovery liquid, and taking the recovery liquid as phosphogypsum re-slurry for circulating reflux;
the conveying pipelines (namely the heat preservation sections) used for the neutralization reaction and the impurity removal treatment are independently provided with heat preservation layers; the heating conveying pipeline (namely a heating section) for crystal transformation is provided with a heating layer; the back end of each step (namely neutralization reaction, impurity removal treatment and crystal transformation) is provided with a solid-liquid separator for respectively carrying out first solid-liquid separation, second solid-liquid separation and third solid-liquid separation.
Example 1
In the embodiment, phosphogypsum re-slurry delivery pipeline is modified according to the flow shown in fig. 1, wherein the pipeline used for neutralization and impurity removal treatment and the inner layer material of the heating pipeline used for crystal transformation are made of polytetrafluoroethylene; the heat-insulating layer is made of rock wool boards; the phosphogypsum reslurry factory is provided with an alkaline substance adding port, and the length of a conveying pipeline used for the neutralization reaction is 5m; the length of the conveying pipeline used for the impurity removal treatment is 5m; the length of the heating conveying pipeline used for crystal transformation is 5m, heating layers are arranged on the whole sections of the heating conveying pipeline, and a quartz heating plate adopted by the heating conveying pipeline is coupled with a probe temperature sensor; the rear end of each section of procedure is provided with a solid-liquid separator.
The method for preparing the alpha high-strength gypsum by semi-in-situ crystal transformation comprises the following steps:
(1) Mixing phosphogypsum reslurry with alkaline substance ammonia water, and sequentially carrying out neutralization reaction and first solid-liquid separation to obtain first liquid and first solid;
the temperature of the phosphogypsum reslurry (just leaving the factory) is 90 ℃; the ratio of the mass of phosphogypsum in the phosphogypsum reslurry to the volume of the phosphogypsum reslurry is 1mg:10mL; the neutralization reaction time is 1h;
the mass of the alkaline substance is 8% of the mass of phosphogypsum reslurry, and the alkaline substance is continuously added along with the transportation process of phosphogypsum; the first solid-liquid separation is natural sedimentation by means of gravity in the conveying process;
(2) Mixing the first solid obtained in the step (1) with hydrochloric acid with the mass fraction of 20%, and sequentially carrying out impurity removal treatment and second solid-liquid separation to obtain a second liquid and a second solid;
the ratio of the mass of the first solid to the volume of the hydrochloric acid with the mass fraction of 20% is 1mg:10mL;
the time of the impurity removal treatment is 2 hours;
(3) Mixing the first liquid obtained in the step (1), the second liquid obtained in the step (2) and crystal transformation agent calcium acetate, performing crystal transformation, and performing third solid-liquid separation on the crystal transformation product to obtain alpha high-strength gypsum and a recovery liquid;
the recovered liquid is used as phosphogypsum reslurry for reflux;
the mass of the crystal transition agent calcium acetate is 5% of the total mass of the first liquid and the second liquid;
the temperature of the crystal transformation is 110 ℃, and the time of the crystal transformation is 2 hours;
the steps (1) - (3) are all carried out in the factory conveying process of phosphogypsum reslurry.
The microstructure of the alpha high-strength gypsum prepared in example 1 was observed by SEM, and the microstructure obtained is shown in fig. 2. As can be seen from fig. 2, the alpha high-strength gypsum prepared in example 1 exhibits a short hexagonal prism-like shape, has good crystallinity, and is relatively uniform.
Example 2
In the embodiment, the phosphogypsum re-slurry delivery pipeline is modified according to the flow shown in fig. 1, wherein the pipeline used for neutralization and impurity removal treatment and the inner layer material of the heating pipeline used for crystal transformation are made of carbon fiber materials; the heat insulation layer is made of an expanded polystyrene board (EPS board); the phosphogypsum reslurry factory is provided with an alkaline substance adding port, and the length of a conveying pipeline used for the neutralization reaction is 10m; the length of the conveying pipeline used for the impurity removal treatment is 15m; the length of the heating conveying pipeline used for crystal transformation is 15m, heating layers are arranged on the whole sections of the heating conveying pipeline, and a quartz heating plate adopted by the heating conveying pipeline is coupled with a probe temperature sensor; the rear end of each section of procedure is provided with a solid-liquid separator.
The method for preparing the alpha high-strength gypsum by semi-in-situ crystal transformation comprises the following steps:
(1) Mixing phosphogypsum reslurry with alkaline substance sodium hydroxide, and sequentially carrying out neutralization reaction and first solid-liquid separation to obtain first liquid and first solid;
the temperature of the phosphogypsum reslurry (just leaving the factory) is 70 ℃; the ratio of the mass of phosphogypsum in the phosphogypsum reslurry to the volume of the phosphogypsum reslurry is 1mg:2mL; the neutralization reaction time is 2h;
the mass of the alkaline substance is 0.5% of the mass of phosphogypsum reslurry, and the alkaline substance is continuously added along with the transportation process of phosphogypsum; the first solid-liquid separation is natural sedimentation by means of gravity in the conveying process;
(2) Mixing the first solid obtained in the step (1) with 5% hydrochloric acid by mass fraction, and then sequentially carrying out impurity removal treatment and second solid-liquid separation to obtain a second liquid and a second solid;
the ratio of the mass of the first solid to the volume of the hydrochloric acid with the mass fraction of 20% is 1mg:5mL; the time of the impurity removal treatment is 1h;
(3) Mixing the first liquid obtained in the step (1), the second liquid obtained in the step (2) and the crystal transformation agent citric acid, performing crystal transformation, and performing third solid-liquid separation on the crystal transformation product to obtain alpha high-strength gypsum and a recovery liquid;
the recovered liquid is used as phosphogypsum reslurry for reflux;
the mass of the crystal transfer agent citric acid is 0.1% of the total mass of the first liquid and the second liquid;
the temperature of the crystal transformation is 90 ℃, and the time of the crystal transformation is 3 hours;
the microstructure of the alpha high-strength gypsum prepared in example 2 was observed by SEM, and the microstructure obtained is shown in fig. 3. As can be seen from fig. 3, the alpha high-strength gypsum prepared in example 2 exhibits a short hexagonal prism-like shape, has good crystallinity, and is relatively uniform.
Example 3
In the embodiment, the phosphogypsum re-slurry delivery pipeline is modified according to the flow shown in fig. 1, wherein the pipeline used for neutralization and impurity removal treatment and the inner layer material of the heating pipeline used for crystal transformation are both made of copper oxide; the heat insulation layer is made of polyurethane foaming material; the phosphogypsum reslurry factory is provided with an alkaline substance adding port, and the length of a conveying pipeline used for the neutralization reaction is 20m; the length of a conveying pipeline used for the impurity removal treatment is 20m; the length of the heating conveying pipeline used for crystal transformation is 20m, heating layers are arranged on the whole sections of the heating conveying pipeline, and a quartz heating plate adopted by the heating conveying pipeline is coupled with a probe temperature sensor; the rear end of each section of procedure is provided with a solid-liquid separator.
The method for preparing the alpha high-strength gypsum by semi-in-situ crystal transformation comprises the following steps:
(1) Mixing phosphogypsum reslurry with alkaline substance potassium hydroxide, and sequentially carrying out neutralization reaction and first solid-liquid separation to obtain first liquid and first solid;
the temperature of the phosphogypsum reslurry (just leaving the factory) is 80 ℃; the ratio of the mass of phosphogypsum in the phosphogypsum reslurry to the volume of the phosphogypsum reslurry is 1mg:5mL; the neutralization reaction time is 3h;
the mass of the alkaline substance is 4% of the mass of phosphogypsum reslurry, and the alkaline substance is continuously added along with the transportation process of phosphogypsum; the first solid-liquid separation is natural sedimentation by means of gravity in the conveying process;
(2) Mixing the first solid obtained in the step (1) with hydrochloric acid with the mass fraction of 10%, and sequentially carrying out impurity removal treatment and second solid-liquid separation to obtain a second liquid and a second solid;
the ratio of the mass of the first solid to the volume of hydrochloric acid with the mass fraction of 10% is 1mg:8mL;
the time of the impurity removal treatment is 2 hours;
(3) Mixing the first liquid obtained in the step (1), the second liquid obtained in the step (2) and the crystal transformation agent citric acid, performing crystal transformation, and performing third solid-liquid separation on the crystal transformation product to obtain alpha high-strength gypsum and a recovery liquid;
the recovered liquid is used as phosphogypsum reslurry for reflux;
the mass of the crystal transfer agent ammonium acetate is 3% of the total mass of the first liquid and the second liquid;
the temperature of the crystal transformation is 100 ℃, and the time of the crystal transformation is 1h;
the microstructure of the alpha high-strength gypsum prepared in example 3 was observed by SEM, and the microstructure obtained is shown in fig. 4. As can be seen from fig. 4, the alpha high-strength gypsum prepared in example 3 exhibits a short hexagonal prism-like shape, has good crystallinity, and is relatively uniform.
In summary, the method provided by the invention uses phosphogypsum as a raw material to produce alpha high-strength gypsum in the process of phosphogypsum reslurry delivery, so that the preparation cost is obviously reduced, semi-in-situ crystal transformation of phosphogypsum is realized, the process flow is simplified, and the alpha high-strength gypsum prepared in examples 1-3 is in a short hexagonal prism shape, has good crystallinity and is relatively uniform.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (10)
1. A method for preparing alpha high-strength gypsum by semi-in-situ crystal transformation comprises the following steps:
(1) Mixing phosphogypsum reslurry with alkaline substances, and sequentially carrying out neutralization reaction and first solid-liquid separation to obtain first liquid and first solid;
(2) Mixing the first solid obtained in the step (1) with hydrochloric acid, and then sequentially carrying out impurity removal treatment and second solid-liquid separation to obtain second liquid and second solid;
(3) Mixing the first liquid obtained in the step (1), the second liquid obtained in the step (2) and a crystal transformation agent, and performing crystal transformation to obtain alpha high-strength gypsum;
the steps (1) - (3) are all carried out in the factory conveying process of phosphogypsum reslurry.
2. The method according to claim 1, wherein the ratio of the mass of phosphogypsum in the phosphogypsum reslurry in step (1) to the volume of phosphogypsum reslurry is 1mg: (1.5-12) mL.
3. The method of claim 1, wherein the phosphogypsum re-slurry in step (1) has a temperature of 70 to 90 ℃.
4. The method of claim 1, wherein the alkaline substance in step (1) is at least one of sodium hydroxide, ammonia, calcium hydroxide, potassium hydroxide, and magnesium hydroxide.
5. A method according to claim 1 or 3, wherein the mass of alkaline material in step (1) is 0.5% to 8% of the mass of phosphogypsum in the phosphogypsum reslurry; the alkaline substance is added continuously in the delivery process of phosphogypsum reslurry.
6. The method according to claim 1, wherein the first solid-liquid separation in step (1) is performed by natural sedimentation.
7. The method according to claim 1, wherein the mass fraction of hydrochloric acid in the step (2) is 5% -20%; the ratio of the mass of the first solid to the volume of hydrochloric acid was 1mg: (5-10) mL.
8. The method of claim 1, wherein the crystal transforming agent in the step (3) is at least one of citric acid, acetic acid, calcium acetate, magnesium acetate, and ammonium acetate; the mass of the crystal transfer agent is 0.1-5% of the total mass of the first liquid and the second liquid.
9. The method according to claim 1, wherein the temperature of the crystals in step (3) is 90 to 110 ℃.
10. The method according to claim 1, wherein the transport pipe for the neutralization reaction in step (1) and the transport pipe for the impurity removal treatment in step (2) are independently provided with heat-insulating layers.
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| US20180257938A1 (en) * | 2015-09-18 | 2018-09-13 | Kingenta Ecological Engineering Group Co., Ltd. | Method for producing phosphoric acid and by-producing alpha-hemihydrate gypsum by wet-process |
| CN115010161A (en) * | 2022-01-19 | 2022-09-06 | 昆明理工大学 | Method for converting waste gypsum into alpha semi-hydrated gypsum |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US20180257938A1 (en) * | 2015-09-18 | 2018-09-13 | Kingenta Ecological Engineering Group Co., Ltd. | Method for producing phosphoric acid and by-producing alpha-hemihydrate gypsum by wet-process |
| CN107487995A (en) * | 2016-06-12 | 2017-12-19 | 李国刚 | A kind of method that alpha type high-strength gypsum is prepared using ardealite |
| CN108147447A (en) * | 2017-12-29 | 2018-06-12 | 应城市嘉鸿技术服务科技有限公司 | A kind of liquid phase method prepares the processing technology of alpha semi-hydrated gypsum |
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