CN110963730A - Preparation process of α type high-strength gypsum - Google Patents
Preparation process of α type high-strength gypsum Download PDFInfo
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- CN110963730A CN110963730A CN201811149014.4A CN201811149014A CN110963730A CN 110963730 A CN110963730 A CN 110963730A CN 201811149014 A CN201811149014 A CN 201811149014A CN 110963730 A CN110963730 A CN 110963730A
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- 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
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/46—Sulfates
- C01F11/466—Conversion of one form of calcium sulfate to another
Abstract
The invention relates to a method for producing α type high-strength gypsum, which comprises the steps of producing and converting a high-quality crystal cylinder by steam pressure and adding a crystal converting agent in a liquid state, pressurizing, steaming and drying, and manufacturing α type ultrahigh-strength gypsum by a one-step method, wherein the semi-aqueous phase, the anhydrous phase and the dihydrate phases of the α type high-strength gypsum prepared by the method are more than or equal to 98 wt%, the rupture strength of 2h is 9.7MPa, and the drying and compression strength of the α type high-strength gypsum is 75.9MPa, which far exceeds the standard of α type high-strength gypsum in the national building material industry.
Description
Technical Field
The invention belongs to the technical field of chemical production, and particularly relates to a method for producing α type high-strength gypsum, which is used for producing and converting a high-quality crystal cylinder by autoclaving and adding a crystal modifier in a liquid state, and producing α type ultrahigh-strength gypsum by a one-step method through pressurization, thermal steaming and drying.
Background
There are two main methods for producing α type high-strength gypsum.
One is a liquid phase method: fine grinding gypsum material, and pressurizing, heating, dehydrating and drying in a liquid state. Because the process is carried out after the gypsum powder is subjected to crystal transformation and molding: firstly, in the process of dehydration and conveying to a dryer, the temperature of the material cannot be kept above 100 ℃ (the crystal transformation gypsum begins to absorb water below 100 ℃), so that about 3-10% of crystal transformation semi-water column and rod-shaped gypsum dihydrate are degraded into irregular forms; secondly, in the dryer, because the temperature of a heat source entering the dryer is limited by heat supply equipment and cannot be uniformly controlled, the temperature in an interval is too high or too low, the contact of material interfaces is different, part of gypsum is converted excessively to generate anhydrous gypsum or is not converted in time to generate dihydrate gypsum, the ratio of the hemihydrate gypsum is reduced, and the performance of the high-strength gypsum is reduced.
The other method is an autoclaved dry method, namely, calcium sulfate powder is subjected to humidifying, pressurizing, heating, drying and crystal modification and fine grinding in a pressure kettle, because the materials of the process are converted in a stacking state, a crystal transformation agent cannot fully enter a material interface for conversion, the growth and the forming of α type gypsum crystals are influenced, in addition, the contact surface of drying gas to the materials is limited, the drying effect is uneven, the quality is easy to be unstable, and the high-strength performance index cannot be completely reached, so that the high-strength gypsum performance is reduced, the product quality is unstable, and the economy is poor.
Disclosure of Invention
The invention aims to solve the technical problem of providing a novel method for producing α type gypsum with ultrahigh strength and ultra-stable performance in a heat-preservation drainage drying device by heating, pressurizing, crystallizing, dehydrating and drying in a liquid state, and the method has the advantages of wide material range, equipment saving and reduced manpower.
The method comprises the following steps:
mixing dihydrate Gypsum Fibrosum powder (CaSO)4.2H2O) and water are added into a still pressure reaction kettle (hereinafter referred to as a reaction kettle) with stirring according to a certain proportion to obtain a mixture;
the dihydrate gypsum powder is selected from one or more of natural gypsum or chemical gypsum, such as natural gypsum, purified phosphogypsum, sulfur gypsum, citric acid gypsum, fluorine gypsum, mirabilite gypsum, titanium gypsum, salt gypsum, ceramic waste mold gypsum and waste paper surface gypsum; the mass ratio of the dihydrate gypsum powder to the water is about 1: 0.3-0.6;
adding a crystal transformation agent into the mixture, and heating and steaming the solid-liquid mixture in the reaction kettle while stirring by utilizing a heat source (for example, a heat source generated by heat conduction oil or steam);
the stirring speed of the stirring is 50-120 r/min;
the steam-pressing temperature is kept at 130-180 ℃, the pressure is kept at 0.15-0.4 MPa, and the time is 1-4 hours;
the crystal transformation agent is selected from one or more of phthalic acid, maleic acid, aluminum sulfate and sodium hydroxide;
the mass ratio of the crystal modifier to the dihydrate gypsum powder is 0.15-14 per mill: 1, preferably 2-9 per mill: 1;
more preferably, the crystal modifier is a mixture of phthalic acid, maleic acid, aluminum sulfate and sodium hydroxide, and the mass ratio of the phthalic acid to the maleic acid to the aluminum sulfate to the sodium hydroxide is (0.02-0.25): 1 (0.02-0.25), more preferably (0.04-0.13): 1 (0.04-0.13);
and then entering a heat preservation drainage drying stage, wherein the heat preservation drainage drying time is 3-5 hours, and cooling and grinding to obtain α type ultrahigh-strength gypsum powder.
In the heat preservation drainage drying stage, the discharge speed and the discharge amount of water vapor are controlled to achieve stable and unchanged pressure, and the discharge amount of surface water and crystal water of the materials is accurately measured by using a discharge water collector until the external water of the finally α type gypsum powder is below 1 wt.% and the internal water is 3-5 wt.%.
The invention provides a new method of one-step method of autoclaved crystal transformation, autoclaved dewatering and steam-frying drying, which is characterized in that during the whole production chain process of transformation from liquid-state slurry to dry powder during crystal transformation growth and forming of gypsum, product materials are all carried out in a rotational flow scattering state in a reaction kettle, the temperature is always kept at 130-180 ℃, the crystal form of α type gypsum is ensured not to be degenerated, the temperature is controllable during drying of the materials, heat energy is fully contacted with the materials without dead angles, the generation of dihydrate gypsum and anhydrous gypsum is greatly reduced, then the materials are cooled to below 60 ℃, stirring and airflow pushing are adopted to simultaneously carry out discharging, and cooling and grinding (material modification) are carried out to obtain the product with 200-400 meshes.
(III) Effect of experiment
The α type high-strength gypsum prepared by the method has the advantages that the semi-aqueous phase of α type high-strength gypsum is more than or equal to 98 wt%, the dihydrate and anhydrous phase of α type high-strength gypsum are less than or equal to 2 wt%, the product performance is 2h, the breaking strength is 9.7MPa, the drying compressive strength is 75.9MPa, and far exceeds the national building material industry standard α type high-strength gypsum (JC/T2038-2010), namely the 2h breaking strength is more than or equal to 6.0MPa, and the drying compressive strength is more than or equal to 50.0 MPa.
Drawings
FIG. 1 is a process flow diagram of the preparation of α type high strength gypsum according to the example.
Description of the reference numerals
1-a heat transfer oil furnace system; 11-an expansion tank; 12-hot oil circulation pump; 13-heat conduction oil furnace; 2-reaction drying comprehensive kettle; 3-a heat exchanger; 41-a condensate pump; 42-condensate pump; 43-a condensate pool; 44-a condensate pool; 45-a cooling water tower; 51-a dust collector; 52-dust collector; 6-intermediate bin; 7-grinding physical modification; and 8-packaging the materials in a bin.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The adopted reaction drying comprehensive kettle is manufactured by Wuhan Sanyi chemical equipment limited company, and is used as raw material dihydrate gypsum (CaSO)4.2H2O) is whisker gypsum, desulfurized gypsum and purified phosphogypsum respectively, wherein the whisker gypsum is self-made by Hubei margin New materials science and technology Limited company (hereinafter called as 'company'), the dry basis purity is 99.5 percent, and the whiteness is 98 percent; the desulfurized gypsum is purchased from a thermal power plant in Jingmen city, the dry-basis purity is 92 percent, and the whiteness is 75 percent; the purified phosphogypsum is self-made by a company, the purity of a dry basis is 93 percent, and the whiteness is 80 percent.
In order to evaluate the performance of the α type high-strength gypsum, the initial and final setting time, the 2h flexural strength and the drying compressive strength are compared with the national building material industry standard α type high-strength gypsum (JC/T2038-2010).
Example 1 As shown in FIG. 1, a whisker gypsum (CaSO) was produced by the same company4.2H2O, the dry basis purity is 99.5 percent, the whiteness is 98 percent) is 5kg, water is 2kg, 1.75g of phthalic acid, 1.75g of maleic acid, 1.75g of sodium hydroxide and 37.5g of aluminum sulfate are added, in the reaction drying comprehensive kettle 2, the heat conduction oil furnace system 1 is utilized to stir, heat and steam the solid water dihydrate gypsum in the reaction drying comprehensive kettle 2, the solid water dihydrate gypsum is heated and steamed at the same time, the temperature is increased to 140 ℃ after 3 hours, and the pressure is increased to 0.25 MPa. Stirring speed in the reaction drying comprehensive kettle 2 is 50 r/min, keeping temperature at 135 ℃ and keeping pressure at 0.20MPa, pumping steam for 4 hours, drying until dry, cooling and discharging, grinding and physically modifying 7 to obtain powder with particle size of 300 meshes, and packaging in a packaging bin 8 to obtain the product.
The test results show that the measured water content in the total mass is 5.6 wt% and the whiteness is 98.5%, the water and the paste are added according to the mass ratio of 30% (mass ratio) to be mixed and processed into strips, and the test results are shown in the following table 1.
TABLE 1
Example 2 use of desulfurized Gypsum (CaSO)4.2H2O, dry basis purity 92%, whiteness 75%) 5kg, water 3kg, then adding 1.5g of phthalic acid, 1.5g of maleic acid, 1.5g of sodium hydroxide and 12.5g of aluminum sulfate, in the reaction drying comprehensive kettle 2, heating and steaming the dihydrate gypsum solid liquid added with water in the reaction drying comprehensive kettle 2 by using steam while stirring, heating to 160 ℃ after 4 hours, and pressurizing to 0.35 MPa. Stirring speed in the reaction drying comprehensive kettle 2 is 120 r/min, steam is pumped out for 4 hours under the conditions of heat preservation at 150 ℃ and pressure preservation of 0.25MPa, drying, cooling and discharging are carried out, grinding physical modification is carried out on the discharged materials 7, powder with the particle size of 350 meshes is obtained, and the powder is packaged in a packaging bin 8 to obtain the product.
The test results show that the measured water content in the total mass is 5.1 wt% and the whiteness is 80%, the water is added according to the water-paste ratio of 33% (mass ratio) to mix the materials and the materials are processed into strips, and the test results are shown in the following table 2.
TABLE 2
Example 3, FIG. 1, the purification of phosphogypsum (CaSO) made by the company4.2H2O), the dry basis purity is 93 percent, the whiteness is 80 percent) is 5kg, water is 2.5kg, 1.3g of phthalic acid, 1.3g of maleic acid, 1.3g of sodium hydroxide and 10g of aluminum sulfate are added, in the reaction drying comprehensive kettle 2, the added dihydrate gypsum solid-liquid in the reaction drying comprehensive kettle 2 is stirred and heated for autoclaving by using a heat conduction oil furnace system 1, the temperature is increased to 165 ℃ after 3.5 hours, and the pressure is increased to 0.3 MPa. Stirring the mixture in the reaction drying comprehensive kettle 2 at the rotating speed of 90 revolutions per minute, keeping the temperature at 145 ℃ and the pressure at 0.25MPa, exhausting steam for 4.5 hours until the mixture is dried, grinding and physically modifying the discharged material for 7 to obtain powder with the particle size of 250 meshes, and packaging the powder in a packaging bin 8 to obtain the product.
The test results show that the measured water content in the total mass is 5.9 wt% and the whiteness is 85%, the water and the mixture are added according to the water-paste ratio of 30% (mass ratio) and processed into strips, and the test results are shown in the following table 3.
TABLE 3
Comparative example 1
The company self-made whisker gypsum (CaSO)4.2H2O, the dry basis purity is 99.5 percent, the whiteness is 98 percent) is 5kg, water is 2kg, 0.175g of phthalic acid, 0.175g of maleic acid, 0.175g of sodium hydroxide and 3.75g of aluminum sulfate are added, in the reaction drying comprehensive kettle 2, the heat conduction oil furnace system 1 is utilized to stir, heat and steam the solid water dihydrate gypsum in the reaction drying comprehensive kettle 2, the solid water dihydrate gypsum is heated and steamed at the same time, the temperature is increased to 140 ℃ after 3 hours, and the pressure is increased to 0.25 MPa. Stirring speed in the reaction drying comprehensive kettle 2 is 50 r/min, keeping temperature at 135 ℃ and keeping pressure at 0.20MPa, pumping steam for 4 hours, drying until dry, cooling and discharging, grinding and physically modifying 7 to obtain powder with particle size of 300 meshes, and packaging in a packaging bin 8 to obtain the product.
The test results show that the measured water content in the total mass is 7.7 wt% and the whiteness is 96.5%, the measured water content and the whiteness are mixed according to the mass ratio of 30% (mass ratio) of water paste, and the mixed water is processed into bars, and the test results are shown in the following table 4.
TABLE 4
Comparative example 2
The company self-made whisker gypsum (CaSO)4.2H2O, the dry basis purity is 99.5 percent, the whiteness is 98 percent) is 5kg, water is 2kg, 3.5g of maleic acid, 1.75g of sodium hydroxide and 37.5g of aluminum sulfate are added, in the reaction drying comprehensive kettle 2, the heat conduction oil furnace system 1 is utilized to stir, heat and steam the dihydrate gypsum solid liquid added with water in the reaction drying comprehensive kettle 2, the temperature is increased to 140 ℃ after 3 hours, and the pressure is increased to 0.25 MPa. Stirring speed in the reaction drying comprehensive kettle 2 is 50 r/min, keeping temperature at 135 ℃ and keeping pressure at 0.20MPa, pumping steam for 4 hours, drying until dry, cooling and discharging, grinding and physically modifying 7 to obtain powder with particle size of 300 meshes, and packaging in a packaging bin 8 to obtain the product.
The test result shows that the measured water content in the total mass is 8.2 wt% and the whiteness is 97.5%, the measured water content and the whiteness are mixed according to the water-paste ratio of 30% (mass ratio) and processed into a bar, and the test result is shown in the following table.
TABLE 5
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A method for preparing α type high-strength gypsum, which is characterized by comprising the following steps:
adding dihydrate gypsum powder and water into a reaction kettle with a stirring function and an autoclaved function according to a certain proportion to obtain a mixture;
adding a crystal transformation agent into the mixture, and heating and steaming the solid-liquid mixture in the reaction kettle while stirring by using a heat source;
then entering a heat preservation, drainage and drying stage, cooling and grinding to obtain α type ultrahigh-strength gypsum powder.
2. The method of claim 1,
the α type gypsum one-step production method is completed in one device by heating, steaming and pressing, crystal transformation, water drainage, drying and drying.
3. The method of claim 1,
the heat source is heat source generated by heat conduction oil or steam; and/or the presence of a gas in the gas,
the dihydrate gypsum powder is selected from one or more of natural gypsum or chemical gypsum, such as natural gypsum, purified phosphogypsum, sulfur gypsum, citric acid gypsum, fluorine gypsum, mirabilite gypsum, titanium gypsum, salt gypsum, ceramic waste mold gypsum and waste paper surface gypsum; and/or the presence of a gas in the gas,
the crystal transformation agent is selected from one or more of phthalic acid, maleic acid, aluminum sulfate and sodium hydroxide.
4. The method of claim 1,
the mass ratio of the dihydrate gypsum powder to the water is about 1: 0.3-0.6.
5. The method of claim 1,
the mass ratio of the crystal modifier to the dihydrate gypsum powder is 0.15-14 per mill: 1, preferably 2-9 per mill: 1.
6. The method of claim 1,
the stirring speed of the stirring is 50-120 r/min; and/or the presence of a gas in the gas,
the steam-pressing temperature is kept at 130-180 ℃, the pressure is kept at 0.15-0.4 MPa, and the time is 1-4 hours.
7. The method of claim 1,
the heat preservation, drainage and drying mode is evaporation discharge, suction and condensation, and then collection and reuse.
8. The method of claim 1,
the time for heat preservation, drainage and drying is 3-5 hours.
9. The method of claim 1, wherein the crystallization agent is a mixture of phthalic acid, maleic acid, aluminum sulfate and sodium hydroxide.
10. The method according to claim 9, wherein the mass ratio of phthalic acid, maleic acid, aluminum sulfate and sodium hydroxide in the crystal modifier is (0.02-0.25): 1 (0.02-0.25), more preferably (0.04-0.13): 1 (0.04-0.13).
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111732398A (en) * | 2020-06-16 | 2020-10-02 | 中建科技武汉有限公司 | Light high-strength assembly type plate based on waste gypsum board and preparation method thereof |
| CN111747717A (en) * | 2020-06-16 | 2020-10-09 | 中建科技武汉有限公司 | High-crack-resistance and high-fracture-resistance assembled plate based on waste gypsum boards and preparation method thereof |
| CN115368100A (en) * | 2022-09-22 | 2022-11-22 | 湖北工业大学 | Preparation method of special cementing material for high-content regenerated gypsum micro-expansion road base |
| CN115951646A (en) * | 2023-03-14 | 2023-04-11 | 一夫科技股份有限公司 | Intelligent production control method and system for alpha-type semi-hydrated gypsum |
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| CN115368100B (en) * | 2022-09-22 | 2023-05-23 | 湖北工业大学 | Preparation method of special cementing material for high-doping-amount regenerated gypsum micro-expansion road base |
| CN115951646A (en) * | 2023-03-14 | 2023-04-11 | 一夫科技股份有限公司 | Intelligent production control method and system for alpha-type semi-hydrated gypsum |
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Application publication date: 20200407 |
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