CN112342624A - Preparation method of alpha calcium sulfate hemihydrate crystal whisker - Google Patents
Preparation method of alpha calcium sulfate hemihydrate crystal whisker Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/60—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape characterised by shape
- C30B29/62—Whiskers or needles
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/46—Sulfur-, selenium- or tellurium-containing compounds
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B7/00—Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions
- C30B7/10—Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions by application of pressure, e.g. hydrothermal processes
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Abstract
The invention discloses a preparation method of alpha calcium sulfate hemihydrate crystal whiskers, belonging to the technical field of material engineering. The preparation method comprises the following steps: and (3) steaming and pressing the calcium sulfate dihydrate crystal whisker, wherein the calcium sulfate dihydrate crystal whisker is positioned above the water surface in a steaming and pressing container with water. The alpha calcium sulfate hemihydrate crystal whisker is prepared by directly steaming and pressing the calcium sulfate dihydrate crystal whisker, so that the preparation efficiency of the alpha calcium sulfate hemihydrate crystal whisker is improved and the cost is reduced compared with the existing method for gradually growing the crystal whisker from solution.
Description
Technical Field
The invention relates to the technical field of material engineering, in particular to a preparation method of alpha calcium sulfate hemihydrate whiskers.
Background
The alpha calcium sulfate hemihydrate crystal whisker consists of coarse, compact and complete primary particles, has higher strength, and has wider application value in engineering compared with the beta calcium sulfate hemihydrate crystal whisker with low strength. At present, the preparation methods such as a hydrothermal method and the like are adopted in laboratories and engineering to prepare the alpha calcium sulfate hemihydrate crystal whisker, so that the efficiency is low and the cost is high.
In view of this, the invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a preparation method of alpha calcium sulfate hemihydrate whiskers, which can improve the preparation efficiency of the alpha calcium sulfate hemihydrate whiskers and reduce the cost.
The invention is realized by the following steps:
the application provides a preparation method of alpha calcium sulfate hemihydrate whiskers, which comprises the following steps: and (3) steaming and pressing the calcium sulfate dihydrate crystal whisker, wherein the calcium sulfate dihydrate crystal whisker is positioned above the water surface in a steaming and pressing container with water.
In an alternative embodiment, the calcium sulfate dihydrate whiskers are 8-30mm from the water surface in the autoclave with water.
In an alternative embodiment, the temperature of the autoclaving is 120-.
In an alternative embodiment, the pressure of the autoclaving is between 0.2MPa and 0.36 MPa.
In an alternative embodiment, the autoclaving time is between 1.5 and 5 h.
In an alternative embodiment, the volume of water in the autoclave is 2-5% of the volume of the autoclave.
In an alternative embodiment, the position 8-30mm away from the water surface of the steam pressure container is provided with a discharging piece.
In an alternative embodiment, the emptying piece is provided with a through hole.
In an alternative embodiment, the aperture of the through-hole is 1-2 mm.
In alternative embodimentsIn the method, the preparation of the calcium sulfate dihydrate whisker comprises the following steps: dissolving CaSO at 60-80 deg.C4·2H2And O, carrying out solid-liquid separation, and cooling the filtrate to crystallize. The materials and instruments used in the solid-liquid separation process are all 60-80 ℃.
In an optional embodiment, the method further comprises cleaning and drying the crystallized crystals.
In an alternative embodiment, the reagent used for dissolution is hydrochloric acid.
In an alternative embodiment, the concentration of hydrochloric acid is 4 to 6 mol/L.
In an alternative embodiment, 0.12 to 0.21mol CaSO is added per L hydrochloric acid4·2H2O。
In an alternative embodiment, a crystallization aid is also added during the dissolution process.
In an alternative embodiment, the seeding aid comprises MgCl2。
In an alternative embodiment, 0.01 to 0.02mol MgCl is added per L hydrochloric acid2。
In an alternative embodiment, CaSO4·2H2O is obtained by removing free water through titanium gypsum.
The beneficial effect of this application includes:
the method for preparing the alpha calcium sulfate hemihydrate crystal whisker is carried out in two steps, wherein the first step is to prepare the calcium sulfate dihydrate crystal whisker under normal pressure, which is beneficial to controlling the shape of the calcium sulfate dihydrate crystal whisker, and the second step is to convert the calcium sulfate dihydrate crystal whisker into the alpha calcium sulfate hemihydrate crystal whisker in a high-pressure container, so that the using amount of water in the high-pressure preparation container can be reduced, and the loading amount of the alpha calcium sulfate hemihydrate crystal whisker finished product in the high-pressure preparation container is increased. Compared with the existing method of gradually growing the crystal whisker from the solution in a high-pressure container by adopting a one-step method, the method can improve the preparation efficiency of the alpha calcium sulfate hemihydrate crystal whisker and reduce the cost.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a process flow diagram provided in application example 1;
FIG. 2 is a graph showing the morphology of calcium sulfate dihydrate whiskers obtained in example 1 of the present application;
FIG. 3 is a scanning electron micrograph of calcium sulfate dihydrate whiskers obtained in example 1 of the present application;
FIG. 4 is a schematic view showing the structure of an autoclave container used in example 1 of the present application;
FIG. 5 is a topographical map of alpha calcium sulfate hemihydrate whiskers obtained in example 1 of the present application;
FIG. 6 is a differential thermal analysis spectrum of alpha calcium sulfate hemihydrate whiskers obtained in example 2 of the present application;
FIG. 7 is a differential thermal analysis spectrum of beta calcium sulfate hemihydrate whiskers obtained in a comparative example of the present application.
Description of the main symbols: 1-water; 2-a porous filter cartridge; 3-a filter cloth net; 4-a triangular support frame; 5-inner container of autoclave.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The following is a specific description of the preparation method of the alpha calcium sulfate hemihydrate crystal whisker provided by the application.
The inventor finds out through research that: at present, the preparation method of the alpha calcium sulfate hemihydrate whisker mainly comprises the step of gradually growing a solution formed by raw materials into the whisker in a preparation container by a hydrothermal method, wherein the raw materials have low solubility in water and small dissolving amount, so a large amount of water (approximately 80% of the volume of the preparation container) is needed, the water needs to occupy more high-pressure containers, and more energy is consumed by heating the water, so that the preparation efficiency of the alpha calcium sulfate hemihydrate whisker is low, and the cost is high.
In view of the above, the present application provides a method for preparing alpha calcium sulfate hemihydrate whiskers, comprising the following steps: and (3) steaming and pressing the calcium sulfate dihydrate crystal whisker, wherein the calcium sulfate dihydrate crystal whisker is positioned above the water surface in a steaming and pressing container with water.
The method mainly utilizes steam formed by water in an autoclave under high pressure to steam-press calcium sulfate dihydrate crystals, so that the crystals are dehydrated to complete crystal transformation and form alpha calcium sulfate hemihydrate crystal whiskers. The method has the advantages that the calcium sulfate dihydrate crystal whisker is directly autoclaved to be directly converted into the alpha calcium sulfate hemihydrate crystal whisker, the crystal whisker form is favorably controlled, the using amount of water in a preparation container can be reduced, the loading amount of an alpha calcium sulfate hemihydrate crystal whisker finished product in the preparation container is increased, and compared with the existing method for gradually growing crystal whisker in solution, the method has the advantages that the used autoclave container is reduced, the energy consumed by heating water is reduced, the preparation efficiency of the alpha calcium sulfate hemihydrate crystal whisker is improved, and the cost is reduced.
In alternative embodiments, the calcium sulfate dihydrate whiskers are positioned 8-30mm, such as 8mm, 10mm, 15mm, 20mm, 25mm, or 30mm, from the water surface in the autoclave with water. Within this range, on the one hand, all calcium sulfate dihydrate whiskers can be covered with water vapor generated from water in the autoclave vessel, and on the other hand, a large amount of alpha calcium sulfate hemihydrate whiskers can be obtained by charging a large amount of raw material into the production vessel with a minimum amount of water.
In alternative embodiments, the volume of water in the autoclave is 2-5% of the volume of the autoclave, such as 2%, 3%, 4%, or 5%, etc. The steam generated by the volume of water can enable the pressure in the autoclave to reach 0.2-0.36MPa at the temperature of 120-140 ℃.
In an optional embodiment, a discharging piece is arranged at the position 8-30mm away from the water surface of the autoclave container to place calcium sulfate dihydrate crystals.
The autoclave vessel may be referred to as an autoclave, which has a reactor inner vessel. The emptying piece can be a net, a plate or a cylinder and the like. The discharging part is provided with a through hole, and the aperture of the through hole can be 1-2mm, such as 1mm, 1.5mm or 2 mm.
In some specific embodiments, a triangular support frame can be arranged in the inner container of the autoclave, a filter cartridge (with multiple holes) is arranged at the top end of the triangular support frame, and a filter cloth net is arranged at the top of the filter cartridge.
In alternative embodiments, the temperature of the autoclaving may be 120-. It is worth saying that the transformation speed of the crystal form of the calcium sulfate dihydrate whisker is low and incomplete when the autoclaving temperature is lower than 120 ℃, the pressure of the autoclave container is too high when the autoclaving temperature is higher than 140 ℃, the manufacturing cost of equipment is increased, explosion accidents are easy to cause for the existing equipment, and the production safety is reduced.
In alternative embodiments, the autoclaving time may be 1.5 to 5 hours, such as 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, or 5 hours, etc. It is worth saying that the autoclaving time is shorter than 1.5h, which easily results in incomplete crystal form transformation of calcium sulfate dihydrate, and longer than 5h, which easily results in long production period and reduced production efficiency.
In an alternative embodiment, the pressure of the autoclave may be 0.2 to 0.36 MPa. It is worth noting that the autoclave pressure lower than 0.2MPa is liable to cause whisker pulverization, and that higher than 0.36MPa is liable to cause equipment cost increase.
By carrying out the autoclaving under the above conditions, on the one hand, the formation of beta calcium sulfate hemihydrate whiskers during the autoclaving process can be avoided. Beta calcium sulfate hemihydrate whiskers are much less strong than alpha calcium sulfate hemihydrate whiskers and are easily powdered. On the other hand, the alpha calcium sulfate hemihydrate crystal whisker can be prepared with higher efficiency than the existing preparation method.
Tests prove that in each preparation, more than 80% of the space in the autoclave can be occupied by the alpha calcium sulfate hemihydrate whiskers, the filling degree of the solution in the autoclave in the prior art is generally lower than 70%, and the volume of the whiskers which can grow is less than 20%.
In an alternative embodiment, the preparation of calcium sulfate dihydrate whiskers comprises: dissolving CaSO at 60-80 deg.C4·2H2O, solid-liquid separation, cooling the filtrate toAnd (4) crystallizing. The solid-liquid separation process uses materials (such as filter paper) and instruments (such as filter flask, funnel and container for filtrate) at 60-80 deg.C.
Alternatively, CaSO4·2H2The O can be obtained by removing free water with titanium gypsum or by preparing with natural gypsum. In the case of titanium gypsum, the titanium gypsum may be obtained by drying, dehydrating and grinding a slurry of titanium gypsum to obtain a powdery titanium gypsum.
In an alternative embodiment, the CaSO is dissolved4·2H2The reagent used for O is hydrochloric acid. By reference, the concentration of hydrochloric acid may be 4 to 6mol/L, such as 4mol/L, 4.5mol/L, 5mol/L, 5.5mol/L, or 6mol/L, and the like. In an alternative embodiment, CaSO is present per L of hydrochloric acid4·2H2The amount of O added may be 0.12 to 0.21mol, such as 0.12mol, 0.15mol, 0.18mol or 0.21mol, etc.
Furthermore, a crystallization promoter can be added in the dissolving process to promote the formation of crystals.
In alternative embodiments, the seeding aid may comprise, for example, MgCl2. Referably, MgCl per liter of hydrochloric acid2The amount of (C) may be 0.01 to 0.02mol, such as 0.01mol, 0.015mol or 0.02 mol.
For reference, the dissolution can be carried out under the heating condition of water bath, and magnetic stirring (preferably uniform stirring) can be carried out during the dissolution process to increase the dissolution speed and the dissolution degree so that CaSO is obtained4·2H2O is completely dissolved.
In the application, solid-liquid separation can be directly carried out by adopting a filtration mode to remove undissolved impurities.
The filtering process may be that the funnel and the filtering flask for hot filtering are first preheated to 60-80 deg.c and then connected to the vacuum system to constitute the vacuum filtering system. Spreading filter paper on the funnel, dissolving CaSO4·2H2And pouring the hydrochloric acid O onto the filter paper, and starting a vacuum system to perform suction filtration.
The cooling may be natural cooling of the filtrate to room temperature, and the cooling process is also crystallization process.
Further, the method can also comprise the step of cleaning and drying the crystallized crystal, thereby obtaining the calcium sulfate dihydrate whisker with higher purity. In the process, the cooled filtrate can be subjected to secondary solid-liquid separation (filtration), and the solid is the required crystal.
It is worth to be noted that, the calcium sulfate dihydrate whisker directly used as the raw material in the present application can be synthesized under normal pressure, while the method of gradually growing the raw material from solution into the whisker in the preparation vessel adopted in the prior art must be carried out under high temperature and high pressure, otherwise, the alpha calcium sulfate hemihydrate whisker cannot be finally generated. Therefore, the preparation method of the alpha calcium sulfate hemihydrate crystal whisker provided by the application has simpler conditions and easier operation.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
This example provides a method for preparing alpha calcium sulfate hemihydrate whiskers.
The method takes titanium gypsum as a raw material to prepare the alpha calcium sulfate hemihydrate crystal whisker, and the process flow diagram can refer to fig. 1, and the specific process can refer to the following steps:
drying and grinding the muddy titanium gypsum to obtain powdered CaSO4·2H2O, the CaSO is added into 6mol/L hydrochloric acid according to the dosage of 0.21mol/L4·2H2O, MgCl is added according to the amount of 0.02mol/L2Heating in water bath to 80 deg.C, and magnetically stirring at uniform speed to obtain CaSO4·2H2And completely dissolving the O to obtain a suspension containing part of impurities.
The funnel and the filtration flask for hot filtration are preheated to 80 ℃, and are connected with a vacuum system to form a vacuum filtration system. Spreading filter paper on the funnel to dissolve CaSO4·2H2Pouring hydrochloric acid (the suspension) of O onto the filter paper, starting a vacuum system, completing the suction filtration process, and respectively obtaining waste residues and clarified liquid.
Naturally cooling the clarified solution to room temperature, filtering, cleaning, and drying for the second time to obtain calcium sulfate dihydrate whisker, wherein the morphology and scanning electron microscope images are respectively shown in FIG. 2 and FIG. 3. FIG. 2 shows calcium sulfate dihydrate whiskers obtained after drying, which are piled up into floccules, and FIG. 3 shows the whiskers in a shape of a slender rod under a scanning electron microscope.
Referring to fig. 4, 25mL of water 1 is added into a 500mL autoclave liner 5, after a triangular support frame 4 and a porous filter cylinder 2 are erected, a filter cloth net 3 is laid on the porous filter cylinder 2, then the obtained calcium sulfate dihydrate whisker is placed on the filter cloth net 3, the autoclave is sealed, heated to 140 ℃, the pressure is 0.36MPa, and the temperature is kept for 2 hours. And cooling, taking out the crystal whisker and drying to obtain the alpha calcium sulfate hemihydrate crystal whisker, wherein the morphology graph and the thermogram of the alpha calcium sulfate hemihydrate crystal whisker are respectively shown in fig. 5 and fig. 6, and fig. 5 shows that the crystal whisker is not pulverized after autoclaved treatment. FIG. 6 shows: the endothermic reaction started at 84.3 ℃ and ended at 112.7 ℃. The peak of the endothermic peak was 106.5 ℃ and the intensity was-1009. mu.V/mg, and the area of the endothermic peak was-229.8. mu.Vs/mg. Also, there is no exothermic peak near 344 ℃ in fig. 6 (compare with fig. 7), indicating that the whiskers are calcium sulfate alpha hemihydrate whiskers.
Wherein the distance between the porous plate and the water surface in the high-pressure kettle is 8mm, and the volume of the calcium sulfate dihydrate crystal whisker in the high-pressure kettle accounts for 85 percent of the volume of the high-pressure kettle.
Example 2
This example also provides a method for preparing alpha calcium sulfate hemihydrate whiskers, which can be referred to as follows:
drying the titanium gypsum to obtain CaSO4·2H2O, adding CaSO into 4mol/L hydrochloric acid according to the dosage of 0.12mol/L4·2H2O, heating MgCl in an amount of 0.01mol/L2Heating to 60 ℃, and carrying out magnetic stirring to ensure that the CaSO4·2H2The O is completely dissolved.
The funnel and the filtration flask for hot filtration are preheated to 60 ℃, and are connected with a vacuum system to form a vacuum filtration system. Spreading filter paper on the funnel to dissolve CaSO4·2H2And pouring the hydrochloric acid O onto the filter paper, and starting a vacuum system to finish the suction filtration process.
And naturally cooling the filtrate to room temperature, and carrying out secondary filtration, cleaning and drying to obtain the calcium sulfate dihydrate crystal whisker.
Adding 10mL of water into a 500mL autoclave, erecting a triangular support frame and a porous plate, laying a filter cloth net on the porous plate, placing the obtained calcium sulfate dihydrate crystal whisker on the filter cloth net, sealing the autoclave, heating to 130 ℃, keeping the pressure at 0.27MPa, and keeping the temperature for 5 hours. And cooling, taking out the crystal whisker and drying to obtain the alpha calcium sulfate hemihydrate crystal whisker.
Wherein the distance between the porous plate and the water surface in the high-pressure kettle is 20mm, and the volume of the calcium sulfate dihydrate crystal whisker in the high-pressure kettle accounts for 82 percent of the volume of the high-pressure kettle.
Example 3
This example also provides a method for preparing alpha calcium sulfate hemihydrate whiskers, which can be referred to as follows:
drying the titanium gypsum to obtain CaSO4·2H2O, adding CaSO into 5mol/L hydrochloric acid according to the dosage of 0.18mol/L4·2H2O, heating MgCl in an amount of 0.015mol/L2Heating to 70 ℃, and carrying out magnetic stirring to ensure that the CaSO is4·2H2The O is completely dissolved.
The funnel and the filtration flask for hot filtration are preheated to 70 ℃, and are connected with a vacuum system to form a vacuum filtration system. Spreading filter paper on the funnel to dissolve CaSO4·2H2And pouring the hydrochloric acid O onto the filter paper, and starting a vacuum system to finish the suction filtration process.
And naturally cooling the filtrate to room temperature, and carrying out secondary filtration, cleaning and drying to obtain the calcium sulfate dihydrate crystal whisker.
Adding 10mL of water into a 500mL autoclave, erecting a triangular support frame and a porous plate, laying a filter cloth net on the porous plate, placing the obtained calcium sulfate dihydrate crystal whisker on the filter cloth net, sealing the autoclave, heating to 120 ℃, keeping the pressure at 0.2MPa, and keeping the temperature for 5 hours. And cooling, taking out the crystal whisker and drying to obtain the alpha calcium sulfate hemihydrate crystal whisker.
Wherein the distance between the porous plate and the water surface in the high-pressure kettle is 30mm, and the volume of the calcium sulfate dihydrate crystal whisker in the high-pressure kettle accounts for 80 percent of the volume of the high-pressure kettle.
Comparative example 1
This comparative example was used to compare with example 1 and beta calcium sulfate hemihydrate whiskers were prepared in the following manner.
Drying titanium gypsum to obtainCaSO4·2H2O, adding CaSO into 6mol/L hydrochloric acid in an amount of 0.21mol/L4·2H2O, heating MgCl in an amount of 0.02mol/L2Heating to 80 ℃, and performing magnetic stirring to ensure that the CaSO is4·2H2The O is completely dissolved.
The funnel and the filtration flask for hot filtration are preheated to 80 ℃, and are connected with a vacuum system to form a vacuum filtration system. Spreading filter paper on the funnel to dissolve CaSO4·2H2And pouring the hydrochloric acid O onto the filter paper, and starting a vacuum system to finish the suction filtration process.
And naturally cooling the filtrate to room temperature, and carrying out secondary filtration, cleaning and drying to obtain the calcium sulfate dihydrate crystal whisker.
Calcium sulfate dihydrate crystal whisker is added into a beaker, heated to 150 ℃ and kept for 2 hours to obtain the beta calcium sulfate hemihydrate crystal whisker, and the thermogram of the beta calcium sulfate hemihydrate crystal whisker is shown in figure 7 respectively, and the endothermic reaction starting temperature point is 108.2 ℃ and the ending temperature point is 144.7 ℃. The peak value of the endothermic peak was 137 ℃, the intensity thereof was-0.58758. mu.V/mg, and the area of the endothermic peak was-179. mu.Vs/mg. The exothermic reaction started at 320.7 ℃ and ended at 360.9 ℃. The peak of the exothermic peak was 344.4 ℃ and the intensity was 0.071208. mu.V/mg, and the peak area of the exothermic peak was 22.91. mu.Vs/mg. It can be seen that there is an exothermic peak around 344 ℃ in fig. 7.
In summary, the calcium sulfate dihydrate whisker is directly autoclaved to be directly converted into the alpha calcium sulfate hemihydrate whisker, so that the whisker form is favorably controlled, the preparation efficiency of the alpha calcium sulfate hemihydrate whisker can be improved by adopting a method of gradually growing the whisker from a solution, and the cost is reduced.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A preparation method of alpha calcium sulfate hemihydrate whiskers is characterized by comprising the following steps: steaming calcium sulfate dihydrate crystal whiskers, wherein the calcium sulfate dihydrate crystal whiskers are positioned above the water surface in a steaming and pressing container with water;
preferably, the temperature of the steam pressure is 120-140 ℃, and the pressure of the steam pressure is 0.2-0.36 MPa.
2. The preparation method according to claim 1, wherein the calcium sulfate dihydrate whisker is at a distance of 8-30mm from the water surface in the autoclave container with water.
3. The method according to claim 1, wherein the autoclaving time is between 1.5 and 5 hours.
4. The method according to claim 1, wherein the volume of water in the autoclave container is 2-5% of the volume of the autoclave container.
5. The preparation method according to claim 1, wherein a discharging piece is arranged at a position 8-30mm away from the water surface of the autoclaved container;
preferably, the discharging part is provided with a through hole;
preferably, the aperture of the through hole is 1-2 mm.
6. The method according to any one of claims 1 to 5, wherein the preparation of the calcium sulfate dihydrate whiskers comprises: dissolving CaSO at 60-80 deg.C4·2H2O, carrying out solid-liquid separation, and cooling the filtrate for crystallization; the materials and instruments used in the solid-liquid separation process are 60-80 ℃;
preferably, the method further comprises cleaning and drying the crystallized whiskers.
7. The method according to claim 6, wherein the dissolving agent is hydrochloric acid;
preferably, the concentration of the hydrochloric acid is 4-6 mol/L.
8. The method according to claim 7, wherein 0.12 to 0.21mol of CaSO is added to each L of the hydrochloric acid4·2H2O。
9. The preparation method according to claim 7, wherein a crystallization promoter is further added during the dissolution;
preferably, the seeding aid comprises MgCl2；
Preferably, 0.01-0.02mol of MgCl is added to each L of the hydrochloric acid2。
10. The method of claim 6, wherein the CaSO4·2H2O is obtained by removing free water through titanium gypsum.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104562209A (en) * | 2014-12-11 | 2015-04-29 | 河南工程学院 | Preparation method of alpha-calcium sulfate hemihydrate crystal whisker by one-step autocatalysis and application thereof |
| WO2015085236A1 (en) * | 2013-12-06 | 2015-06-11 | Flint Hills Resources, Lp | Gypsum composite modifiers |
| CN104846440A (en) * | 2015-05-29 | 2015-08-19 | 昆明冶金研究院 | Method for preparing high-purity calcium sulfate dihydrate crystal whisker by using metallurgic flue gas desulfurization gypsum recrystallization process |
| CN104928752A (en) * | 2015-07-06 | 2015-09-23 | 宁远县隆翔新型材料科技有限公司 | Method for preparing calcium sulphate dihydrate crystal whiskers at normal temperature and method thereof for converting calcium sulphate dihydrate crystal whiskers into anhydrous crystal whiskers at normal pressure |
| CN110835780A (en) * | 2019-10-28 | 2020-02-25 | 昆明理工大学 | Method for preparing nanometer α type calcium sulfate hemihydrate crystal whisker from phosphogypsum in reverse microemulsion system |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015085236A1 (en) * | 2013-12-06 | 2015-06-11 | Flint Hills Resources, Lp | Gypsum composite modifiers |
| CN104562209A (en) * | 2014-12-11 | 2015-04-29 | 河南工程学院 | Preparation method of alpha-calcium sulfate hemihydrate crystal whisker by one-step autocatalysis and application thereof |
| CN104846440A (en) * | 2015-05-29 | 2015-08-19 | 昆明冶金研究院 | Method for preparing high-purity calcium sulfate dihydrate crystal whisker by using metallurgic flue gas desulfurization gypsum recrystallization process |
| CN104928752A (en) * | 2015-07-06 | 2015-09-23 | 宁远县隆翔新型材料科技有限公司 | Method for preparing calcium sulphate dihydrate crystal whiskers at normal temperature and method thereof for converting calcium sulphate dihydrate crystal whiskers into anhydrous crystal whiskers at normal pressure |
| CN110835780A (en) * | 2019-10-28 | 2020-02-25 | 昆明理工大学 | Method for preparing nanometer α type calcium sulfate hemihydrate crystal whisker from phosphogypsum in reverse microemulsion system |
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