WO2023116213A1 - α型半水石膏的制备方法 - Google Patents

α型半水石膏的制备方法 Download PDF

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WO2023116213A1
WO2023116213A1 PCT/CN2022/129177 CN2022129177W WO2023116213A1 WO 2023116213 A1 WO2023116213 A1 WO 2023116213A1 CN 2022129177 W CN2022129177 W CN 2022129177W WO 2023116213 A1 WO2023116213 A1 WO 2023116213A1
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gypsum
strength
hemihydrate gypsum
type high
desulfurized
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PCT/CN2022/129177
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English (en)
French (fr)
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朱建平
张臣
冯春花
刘慧杰
王麒麟
管学茂
张素娟
黄金城
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河南理工大学
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Priority to SE2350965A priority Critical patent/SE2350965A1/en
Publication of WO2023116213A1 publication Critical patent/WO2023116213A1/zh

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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
    • 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
    • C04B11/26—Calcium sulfate cements strating from chemical gypsum; starting from phosphogypsum or from waste, e.g. purification products of smoke
    • C04B11/262—Calcium sulfate cements strating from chemical gypsum; starting from phosphogypsum or from waste, e.g. purification products of smoke waste gypsum other than phosphogypsum
    • C04B11/264—Gypsum from the desulfurisation of flue gases

Definitions

  • the invention belongs to the technical field of building materials, and in particular relates to a preparation method of ⁇ -type hemihydrate gypsum.
  • ⁇ -hemihydrate gypsum (CaSO 4 ⁇ 0.5H 2 O, ⁇ -HH) from desulfurized gypsum is one of the most valuable research directions for its resource utilization.
  • ⁇ -hemihydrate gypsum is an intermediate product formed by dehydration of dihydrate gypsum, also known as high-strength gypsum.
  • ⁇ -type high-strength hemihydrate gypsum has the characteristics of complete crystal plane, low heat of hydration, less water demand, and high strength of hardened body. It is widely used in the fields of building materials, ceramics, precision mold casting, bone cement, and pharmaceutical carriers.
  • Atmospheric pressure salt (alcohol) solution method is to prepare ⁇ -type high-strength gypsum under normal pressure on the basis of reducing water activity, but the introduction of salt medium may interfere with the effect of the crystal modifier and affect the quality of the product .
  • the autoclave method has relatively high requirements for gypsum raw materials, which are generally high-grade natural gypsum and alabaster, and is not suitable for the preparation of ⁇ -type high-strength hemihydrate gypsum from desulfurization gypsum and other industrial by-product gypsum.
  • the by-product gypsum is prepared by this method.
  • ⁇ -type high-strength hemihydrate gypsum often has incomplete crystal development.
  • the pressurized aqueous solution method only needs to introduce a small amount of crystal modifier to obtain ⁇ -type high-strength hemihydrate gypsum with a complete crystallization degree, and the requirements for raw materials are not high, which meets the requirements of using industrial by-product gypsum to prepare ⁇ -type high-strength hemihydrate gypsum. , has a good application prospect.
  • the planes where ⁇ -type high-strength hemihydrate gypsum grows along the c-axis are (110) and (010). If there is no crystal modifier added, ⁇ -type high-strength hemihydrate gypsum tends to grow along these planes, and finally grows into needles. shape.
  • the addition of the crystal modifier will be adsorbed on the (111) top surface of the ⁇ -type high-strength hemihydrate gypsum crystal to inhibit the growth along the c-axis, and an ideal short columnar crystal with an aspect ratio close to 1:1 can be obtained.
  • crystal modifiers in the existing technology that have achieved certain results.
  • the object of the present invention is to provide a kind of ⁇ -type high-strength hemihydrate gypsum and preparation method thereof, to at least solve or improve the organic acid crystal transformation agent used in the prior art on the (111) plane of ⁇ -type high-strength hemihydrate gypsum crystal
  • the absolute value of the adsorption energy is small, and it is difficult to obtain ideal short columnar ⁇ -type high-strength hemihydrate gypsum crystals with an aspect ratio of 1:1 or organic acid-acid crystal modifiers are more effective in improving the compressive strength of ⁇ -type high-strength hemihydrate gypsum. bad question.
  • both succinic acid and glutaric acid are dibasic carboxylic acids, and succinic acid has a good crystallization effect, but the preparation of succinic acid
  • the dosage of ⁇ -high strength hemihydrate gypsum is very high to achieve low aspect ratio and high strength.
  • the crystal transformation effect of glutaric acid is poor, and its strength is almost the same as that of ⁇ -type hemihydrate gypsum without crystal transformation agent.
  • the difference between succinic acid and glutaric acid is that the distance between carboxyl groups in succinic acid is 2 C atoms, and the distance between carboxyl groups in glutaric acid is 3 C atoms. Effects make an impact. Therefore, the inventor selected glyceric acid, which has not yet been explored, and added a carboxyl group on the branch chain of the glutaric acid structure as a crystal modifier, so that the carboxyl group of the branch chain and the carboxyl group of the main chain are separated by 2 C atoms. , to prepare ⁇ -type high-strength hemihydrate gypsum.
  • the present invention provides the following technical scheme: a preparation method of ⁇ -type hemihydrate gypsum, comprising the following steps: (1) reacting the desulfurized gypsum suspension and glyceric acid at 120-140°C for 3-5h ; (2) Solid-liquid separation, 40-80 °C vacuum drying, that is, ⁇ -type hemihydrate gypsum.
  • the present invention also provides an ⁇ -type hemihydrate gypsum: the ⁇ -type hemihydrate gypsum is prepared by the above preparation method.
  • ⁇ -type hemihydrate gypsum is a short columnar crystal; the aspect ratio of ⁇ -type hemihydrate gypsum is (0.5-2.0):1.
  • the compressive strength of ⁇ -type high-strength hemihydrate gypsum is >35MPa.
  • the preparation method of ⁇ -type hemihydrate gypsum of the present invention adopts glyceric acid as a crystal-transforming agent, which only contains three carboxyl groups, and every two adjacent carboxyl groups are separated by two C atoms, and does not contain complicated Ineffective groups can make ⁇ -high-strength gypsum tend to develop radially, obtain short columnar ⁇ -high-strength gypsum crystals, increase the strength of ⁇ -high-strength gypsum, and contribute to the resource utilization of desulfurized gypsum.
  • the ⁇ -type high-strength hemihydrate gypsum is obtained by drying at 40-80° C., which helps to avoid destroying 0.5 crystal water in the ⁇ -type high-strength hemihydrate gypsum.
  • the preparation method of the invention is simple and easy to operate, and can realize the industrialized production of alpha-type high-strength hemihydrate gypsum.
  • the ⁇ -type high-strength hemihydrate gypsum prepared by the preparation method of the invention is in the shape of a short column, the length-to-diameter ratio can reach 1.0, and the drying compressive strength can reach 43.6 MPa.
  • Fig. 1 is the structural formula of glyceric acid
  • Figure 2 is the crystal morphology of ⁇ -type high-strength hemihydrate gypsum
  • Figure 3 is an optical micrograph of the alpha-type high-strength hemihydrate gypsum prepared when the concentration of glyceric acid provided in Example 1 is 1.0mM;
  • Figure 4 is an optical micrograph of the ⁇ -type high-strength hemihydrate gypsum prepared when the concentration of glyceric acid provided in Example 1 is 1.5mM;
  • Figure 5 is an optical micrograph of the ⁇ -type high-strength hemihydrate gypsum prepared when the concentration of glyceric acid provided in Example 1 is 2.0mM;
  • Figure 6 is an optical micrograph of the ⁇ -type high-strength hemihydrate gypsum prepared when the concentration of glyceric acid provided in Example 1 is 2.5mM;
  • Figure 7 is an optical micrograph of the ⁇ -type high-strength hemihydrate gypsum prepared when the concentration of glyceric acid provided in Example 1 is 3.0mM;
  • Figure 8 is an optical micrograph of the ⁇ -type high-strength hemihydrate gypsum prepared when the concentration of glyceric acid provided in Example 1 is 3.5mM;
  • Figure 9 is an optical micrograph of ⁇ -type high-strength hemihydrate gypsum prepared when the concentration of glyceric acid provided in Example 1 is 4.0mM;
  • FIG. 10 is an optical micrograph of the product prepared in Comparative Example 1 without adding a crystal modifier.
  • the present invention aims at the existing existing desulfurization gypsum as raw material, when the desulfurization gypsum is treated with a commonly used organic acid crystal transfer agent, the absolute value of the adsorption energy on the (111) surface of the ⁇ -type hemihydrate gypsum crystal is small, and it is difficult to obtain a long diameter
  • the ideal short columnar ⁇ -type hemihydrate gypsum crystal or organic acid crystallization agent with a ratio of 1:1 is less effective in improving the compressive strength of ⁇ -type gypsum, and a method for preparing ⁇ -type hemihydrate gypsum is provided.
  • the ⁇ -type hemihydrate gypsum of the invention has good compressive strength and high performance, that is, a preparation method of the ⁇ -type high-strength hemihydrate gypsum.
  • the preparation method of the ⁇ -type high-strength hemihydrate gypsum in the embodiment of the present invention comprises the following steps: (1) reacting the suspension of desulfurized gypsum and glyceric acid at 120-140° C. for 3-5 hours; (2) separating solid and liquid, 40 Vacuum drying at -80°C to obtain ⁇ -type high-strength hemihydrate gypsum.
  • reaction temperature of desulfurized gypsum suspension and glyceric acid is lower than 120°C, the conversion rate of ⁇ -type hemihydrate gypsum is low, and the strength after molding is low; if the reaction temperature is higher than 140°C, the ⁇ -type hemihydrate will be destroyed. The integrity of hydrogypsum crystals results in higher water consumption and lower strength for standard consistency.
  • reaction time is less than 3 hours, it is found that the conversion of ⁇ -type high-strength hemihydrate gypsum is insufficient, and some dihydrate gypsum fails to react in time, which affects the strength of the product.
  • the reaction time should not be higher than 5h for the sake of energy saving under the condition of satisfying the shape and strength of the product.
  • the crystal modifier used is glyceric acid (structural formula shown in Figure 1), which has 3 carboxyl groups, and the distance between two adjacent carboxyl groups is 2 C atoms.
  • the crystal modifier can produce strong adsorption on the surface of ⁇ -type high-strength hemihydrate gypsum (111), and inhibit the growth of ⁇ -type high-strength hemihydrate gypsum along the axial direction (the crystal morphology of ⁇ -type high-strength hemihydrate gypsum is shown in Figure 2 ), so that the ⁇ -type high-strength hemihydrate gypsum tends to develop radially, and the short columnar ⁇ -type high-strength hemihydrate gypsum is obtained, which increases the strength of the ⁇ -type high-strength hemihydrate gypsum, which in turn contributes to the resource utilization of desulfurized gypsum.
  • step (2) adopting a drying temperature of 40-80°C after solid-liquid separation helps to prevent the destruction of 0.5 crystal water in ⁇ -type high-strength hemihydrate gypsum due to excessive temperature, which affects the ⁇ -type high-strength hemihydrate.
  • the strength of water gypsum is the strength of water gypsum.
  • step (1) is carried out under stirring conditions, and the stirring speed is 250-350r/min. Too low stirring speed will lead to uneven stirring of raw materials and agglomeration, which will affect the conversion and performance of the product. Excessively high stirring speed will increase the friction between ⁇ hemihydrate gypsum crystals, resulting in an increase in aspect ratio and a decrease in strength.
  • the concentration of glyceric acid is 1-4mM.
  • the concentration of glyceric acid is 2.5-3.5mM
  • the reaction temperature is 130-140°C
  • the reaction time is 4-5h.
  • the desulfurized gypsum suspension is prepared by using desulfurized gypsum and water; in the desulfurized gypsum suspension, the concentration of desulfurized gypsum is 10-30wt%.
  • concentration of desulfurized gypsum exceeds 30wt%, deposition is prone to occur, resulting in part of the desulfurized gypsum not being converted into hemihydrate gypsum, which affects the strength of the product.
  • the steps of cleaning and vacuum drying the desulfurized gypsum are also included before step (1); the cleaning includes the step of washing the desulfurized gypsum with water; the temperature of vacuum drying is 40-60°C.
  • the steps of cleaning and vacuum drying the desulfurized gypsum are also included before step (1); the cleaning includes the step of washing the desulfurized gypsum with water; the temperature of vacuum drying is 40-60°C.
  • the solid-liquid separation also includes the step of washing the obtained solid product with absolute ethanol as a hydration inhibitor.
  • absolute ethanol as a hydration inhibitor, the solid obtained from solid-liquid separation (suction filter can be used to achieve solid-liquid separation) is repeatedly washed to help prevent the hydration of the newly formed ⁇ -type high-strength hemihydrate gypsum . In actual industrial production, if the speed between solid-liquid separation and drying is very fast, this step can also be omitted.
  • the time for vacuum drying is 20-24h.
  • the present invention also proposes an ⁇ -type high-strength hemihydrate gypsum, and the ⁇ -type high-strength hemihydrate gypsum in the embodiment of the present invention is prepared by the above method.
  • the ⁇ -type high-strength hemihydrate gypsum is a short columnar crystal; the aspect ratio of the ⁇ -type high-strength hemihydrate gypsum is (0.5-2.0):1.
  • the aspect ratio of the ⁇ -type high-strength hemihydrate gypsum is (0.8-1.1):1.
  • the compressive strength of the ⁇ -type high-strength hemihydrate gypsum is greater than 35 MPa.
  • the compressive strength of the ⁇ -type high-strength hemihydrate gypsum is greater than 40.5 MPa.
  • the desulfurized gypsum is taken from a thermal power plant in Jiaozuo City, Henan province, the main component is composed of CaSO 4 2H 2 O, and contains a small amount of SiO 2 and CaCO 3 ; analysis of pure glyceric acid (C 6 H 8 O 6 , 99.0%), glutaric acid (C 5 H 8 O 4 , 99.0%) and succinic acid (C 6 H 8 O 7 , 99.7%) were produced by Shanghai Macklin Biochemical Technology Co., Ltd.; absolute ethanol (CH 3 CH 2 OH, 99.7%) was produced by Hongyan Reagent Factory, Hedong District, Tianjin.
  • the preparation method of the ⁇ -type high-strength hemihydrate gypsum of the present embodiment comprises the following steps:
  • step (2) adopt water and the desulfurized gypsum after step (1) cleaning and drying according to the ratio of solid-to-liquid ratio of 1:5 to prepare desulfurized gypsum suspension (in the desulfurized gypsum suspension, the concentration of desulfurized gypsum is 20wt%, respectively to 7
  • Add glyceric acid crystal-transforming agent to the above-mentioned desulfurized gypsum suspension so that the final concentration of glyceric acid crystal-transforming agent in the desulfurized gypsum suspension is 1-4mM (with a gradient of 0.5mM), and put it into the reactor;
  • desulfurization gypsum is processed according to the following method, including the following steps:
  • step (2) Using water and the desulfurized gypsum cleaned and dried in step (1) to prepare a desulfurized gypsum suspension (in the desulfurized gypsum suspension, the concentration of desulfurized gypsum is 10wt%), and adding glyceric acid to the above-mentioned desulfurized gypsum suspension A crystal-transforming agent, so that the final concentration of the glyceric acid crystal-transforming agent in the desulfurized gypsum suspension is 3mM, and put into the reaction kettle;
  • desulfurization gypsum is processed according to the following method, including the following steps:
  • step (2) Using water and the desulfurized gypsum cleaned and dried in step (1) to prepare a desulfurized gypsum suspension (in the desulfurized gypsum suspension, the concentration of desulfurized gypsum is 30wt%), and adding glyceric acid to the above-mentioned desulfurized gypsum suspension A crystal-transforming agent, so that the final concentration of the glyceric acid crystal-transforming agent in the desulfurized gypsum suspension is 3mM, and put into the reaction kettle;
  • desulfurization gypsum is processed according to the following method, including the following steps:
  • step (2) adopt water and the desulfurized gypsum after step (1) cleaning and drying to prepare desulfurized gypsum suspension (in the desulfurized gypsum suspension, the concentration of desulfurized gypsum is 20wt%), add glyceric acid in the above-mentioned desulfurized gypsum suspension A crystal-transforming agent, so that the final concentration of the glyceric acid crystal-transforming agent in the desulfurized gypsum suspension is 3mM, and put into the reaction kettle;
  • desulfurization gypsum is processed according to the following method, including the following steps:
  • step (2) adopt water and the desulfurized gypsum after step (1) cleaning and drying to prepare desulfurized gypsum suspension (in the desulfurized gypsum suspension, the concentration of desulfurized gypsum is 20wt%), add glyceric acid in the above-mentioned desulfurized gypsum suspension A crystal-transforming agent, so that the final concentration of the glyceric acid crystal-transforming agent in the desulfurized gypsum suspension is 3mM, and put into the reaction kettle;
  • desulfurization gypsum is processed according to the following method, including the following steps:
  • step (2) adopt water and the desulfurized gypsum after step (1) cleaning and drying to prepare desulfurized gypsum suspension (in the desulfurized gypsum suspension, the concentration of desulfurized gypsum is 20wt%), add glyceric acid in the above-mentioned desulfurized gypsum suspension A crystal-transforming agent, so that the final concentration of the glyceric acid crystal-transforming agent in the desulfurized gypsum suspension is 3mM, and put into the reaction kettle;
  • desulfurization gypsum is processed according to the following method, including the following steps:
  • step (2) adopt water and the desulfurized gypsum after step (1) cleaning and drying to prepare desulfurized gypsum suspension (in the desulfurized gypsum suspension, the concentration of desulfurized gypsum is 20wt%), add glyceric acid in the above-mentioned desulfurized gypsum suspension A crystal-transforming agent, so that the final concentration of the glyceric acid crystal-transforming agent in the desulfurized gypsum suspension is 3mM, and put into the reaction kettle;
  • desulfurization gypsum is processed according to the following method, including the following steps:
  • step (2) adopt water and the desulfurized gypsum after step (1) cleaning and drying to prepare desulfurized gypsum suspension (in the desulfurized gypsum suspension, the concentration of desulfurized gypsum is 20wt%), add glyceric acid in the above-mentioned desulfurized gypsum suspension A crystal-transforming agent, so that the final concentration of the glyceric acid crystal-transforming agent in the desulfurized gypsum suspension is 3mM, and put into the reaction kettle;
  • desulfurization gypsum is processed according to the following method, including the following steps:
  • step (2) Use water and the desulfurized gypsum cleaned and dried in step (1) to prepare a desulfurized gypsum suspension (in the desulfurized gypsum suspension, the concentration of desulfurized gypsum is 20wt%), and add glycerine to the above-mentioned desulfurized gypsum suspension Acid crystal-transforming agent, so that the final concentration of glyceric acid crystal-transforming agent in the desulfurized gypsum suspension is 3mM, and put into the reaction kettle;
  • desulfurization gypsum is processed according to the following method, including the following steps:
  • step (2) Use water and the desulfurized gypsum cleaned and dried in step (1) to prepare a desulfurized gypsum suspension (in the desulfurized gypsum suspension, the concentration of desulfurized gypsum is 20wt%), and add glycerine to the above-mentioned desulfurized gypsum suspension Acid crystal-transforming agent, so that the final concentration of glyceric acid crystal-transforming agent in the desulfurized gypsum suspension is 3mM, and put into the reaction kettle;
  • This comparative example processes the desulfurization gypsum according to the following method, comprising the following steps:
  • This comparative example processes the desulfurization gypsum according to the following method, comprising the following steps:
  • This comparative example processes the desulfurization gypsum according to the following method, comprising the following steps:
  • the concentration of succinic acid in step (2) is 9mM, the effect of crystal transformation is the best; therefore, in this comparative example, the concentration of succinic acid crystal transformation agent is set to 9mM.
  • Example 1 The only difference between this comparative example and Example 1 (the final concentration of the glyceric acid crystal-transforming agent is 3 mM) is that the reaction temperature in step (3) is 160° C.; the rest are consistent with Example 1.
  • Example 1 The only difference between this comparative example and Example 1 (the final concentration of the glyceric acid crystal-transforming agent is 3mM) is that the stirring speed in step (3) is 400r/min; the rest are consistent with Example 1.
  • Example 1 The only difference between this comparative example and Example 1 (the final concentration of the glyceric acid crystal-transforming agent is 3mM) is that the stirring speed in step (3) is 450r/min; the rest are consistent with Example 1.
  • Example 1 The only difference between this comparative example and Example 1 (the final concentration of the glyceric acid crystal-transforming agent is 3mM) is that the stirring speed in step (3) is 500r/min; the rest are consistent with Example 1.
  • Example 1 The only difference between this comparative example and Example 1 (the final concentration of the glyceric acid crystal-transforming agent is 3 mM) is that in step (4), the vacuum drying temperature is 100° C., and the rest are consistent with Example 1.
  • Example 1 The only difference between this comparative example and Example 1 (the final concentration of the glyceric acid crystal-transforming agent is 3 mM) is that in step (4), the vacuum drying temperature is 120° C., and the rest are consistent with Example 1.
  • Example 1 The only difference between this comparative example and Example 1 (the final concentration of the glyceric acid crystal-transforming agent is 3 mM) is that in step (4), the vacuum drying temperature is 140° C., and the rest are consistent with Example 1.
  • the adsorption energies of citric acid, glutaric acid, succinic acid and glyceric acid on the (111) surface of ⁇ -type high-strength hemihydrate gypsum crystals are respectively -100KJ/mol, -135KJ/mol, -121KJ/mol mol and -183KJ/mol.
  • the absolute value of the adsorption energy of glutaric acid on the (010) surface of ⁇ -high-strength gypsum is the largest at -389KJ/mol, indicating that glutaric acid is preferentially adsorbed on the (010) surface and the crystal transformation effect is not good.
  • the absolute value of the adsorption energy of glyceric acid on the surface of ⁇ -high-strength hemihydrate gypsum (111) is larger than that of citric acid, succinic acid and glutaric acid, and the effect of crystal transformation is better.
  • the aspect ratio and drying compressive strength of the ⁇ -type high-strength hemihydrate gypsum prepared in the above-mentioned embodiment 1 and comparative example 1-2 (referring to the corresponding in JC/T 2038-2010 ( ⁇ -type high-strength gypsum) method) to test (the test sample is ground to 200 mesh or finer).
  • the aspect ratio test method of crystal comprises the steps:
  • Table 2 The aspect ratio and drying compressive strength of the ⁇ -type high-strength hemihydrate gypsum crystals prepared in Example 1 and Comparative Examples 1-12
  • Example 1 Glyceric acid - 1.0mM 1.7:1 35.3
  • Example 1 Glyceric acid - 1.5mM 1.3:1 38.6
  • Example 1 Glyceric acid - 2.0mM 1.2:1 39.2
  • Example 1 Glyceric acid - 2.5mM 1.1:1 40.9
  • Example 1 Glyceric acid - 3.0mM 1.0:1 43.6
  • Example 1 Glyceric acid - 3.5mM 0.8:1 42.1
  • Example 2 Desulfurization gypsum 10wt% 0.8:1 39.2
  • Example 3 Desulfurization gypsum 30wt% 1.8:1 37.4
  • Example 4 Reaction temperature 120°C 2.0:1 35.1
  • Example 5 Reaction temperature 140°C 1.3:1 42.4
  • Example 6 Stirring speed 250r/min 1.5:1 37.6
  • Example 7 Stir
  • Comparative example 3 Succinic acid - 9mM 1.2:1 40.1 Comparative example 4 Reaction temperature 160°C 2.8:1 32.5 Comparative example 5 Stirring speed 400r/min 2.0:1 35.0 Comparative example 6 Stirring speed 450r/min 2.6:1 30.0 Comparative example 7 Stirring speed 500r/min 3.3:1 26.2 Comparative example 8 Dry at 100°C 1.0:1 42.9 Comparative example 9 Dry at 120°C 1.0:1 42.3 Comparative example 10 Dry at 140°C 1.0:1 41.2
  • the aspect ratio of ⁇ -type high-strength gypsum crystals becomes lower and lower, and its drying compressive strength reaches the maximum when reaching the ideal crystal with an aspect ratio of 1:1.
  • the crystal-transforming agent of the present invention is beneficial to the preparation of ⁇ -type high-strength Gypsum has a significant positive effect.
  • Example 1 In conjunction with Example 1, Examples 4-5 and Comparative Example 4, it can be seen that when the reaction temperature was 120°C, the conversion rate of ⁇ -type high-strength hemihydrate gypsum was low, and the strength after molding was low; the temperature was higher than 140°C (such as 160°C ) will destroy the integrity of ⁇ hemihydrate gypsum crystals, resulting in increased water consumption and reduced strength for standard consistency.
  • Example 1 In combination with Example 1, Examples 6 and 7 and Comparative Examples 5-7, it can be seen that too low stirring speed will lead to uneven stirring of raw materials and agglomeration, which will affect the conversion and performance of the product. Excessively high stirring speed will increase the friction between ⁇ -type high-strength hemihydrate gypsum crystals, resulting in an increase in aspect ratio and a decrease in strength.
  • Examples 1, 8 and 9 illustrate that when the reaction time is 3 hours, the conversion of ⁇ -type high-strength hemihydrate gypsum is insufficient, and some dihydrate gypsum fails to react in time to affect the strength of the product. At the same time, the reaction time should not be higher than 5h for the sake of energy saving under the condition of satisfying the shape and strength of the product.
  • Example 10 In conjunction with Example 1, Example 10 and Comparative Examples 8-10, it can be seen that as the drying temperature increases, the compressive strength of the prepared ⁇ -type high-strength hemihydrate gypsum gradually decreases, and a lower drying temperature should be selected as far as possible to ensure Avoid destroying 0.5 crystal water in ⁇ -type high-strength hemihydrate gypsum.

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Abstract

α型半水石膏的制备方法包括下述步骤：（1）使脱硫石膏悬浮液和丙三酸在120-140℃下反应3-5h；（2）固液分离，40-80℃真空干燥，即得α型高强半水石膏。α型高强半水石膏的制备方法通过采用丙三酸作为转晶剂，其仅含有三个羧基基团，且每两个相邻的羧基间距均为两个C原子，不含有复杂的无效基团，可使α高强石膏趋于径向发展，得到短柱状的α高强石膏晶体，增加α高强石膏的强度，有助于脱硫石膏的资源化利用。

Description

α型半水石膏制备方法 技术领域
本发明属于建筑材料技术领域，具体涉及一种α型半水石膏制备方法。
背景技术
目前，利用脱硫石膏制备α-半水石膏(CaSO 4·0.5H 2O，α-HH)是其资源化利用最有价值的研究方向之一。α-半水石膏是二水石膏脱水生成的中间产物，又称高强石膏。α型高强半水石膏具有晶面完整、水化热低、需水量少、硬化体强度高等特点，被广泛用于建材、陶瓷、精密模铸、骨水泥、医药载体等领域。制备α型高强半水石膏的方法有三类：常压盐(醇)溶液法，饱和蒸气加压法(蒸压法)和加压水热法。常压盐(醇)溶液法是在降低水活性的基础上实现在常压的条件下来制备α型高强石膏，但由于盐介质的引入可能会对转晶剂效果带来干扰，影响产品的质量。蒸压法对石膏原料的要求比较高，一般为品位较高的天然石膏和雪花石膏，不适合脱硫石膏以及其他工业副产石膏制备α型高强半水石膏，副产石膏用此方法制备出的α型高强半水石膏经常晶体发育不完整。而使用加压水溶液法只需引入少量转晶剂，就可得到结晶程度完整α型高强半水石膏，且对原料的要求不高，满足使用工业副产石膏制备α型高强半水石膏的要求，有良好的应用前景。
自然环境下α型高强半水石膏沿c轴生长的面为(110)和(010)，如果没有转晶剂的加入，α型高强半水石膏倾向于沿着这些面生长，最终长成针状。转晶剂的加入会吸附在α型高强半水石膏晶体的(111)顶面从而抑制沿c轴的生长，能够得到长径比接近1:1的理想短柱状晶体。现有的技术中也有很多转晶剂取得了一定的效果，然而，还有很多有机酸类的转晶剂并不能有效吸附在α型半水石膏晶体的(111)面从而达到良好的转晶效果。制备α型高强半水石膏时使用的转晶剂的用量大且得到的α型高强半水石膏的性能有待进一步提高。所以，开发一种能够使α型高强半水石膏晶体的长径比达到1:1理想短柱状且用量低、性能优异的转晶剂仍有必要。
因此，需要提供一种针对上述现有技术不足的改进技术方案。
发明内容
本发明的目的在于提供一种α型高强半水石膏及其制备方法，以至少解决或改善现有技术中所使用的有机酸转晶剂在α型高强半水石膏晶体的(111)面的吸附能的绝对值小、不易得到长径比为1:1的理想短柱状的α型高强半水石膏晶体或有机酸酸转晶剂对α型高强半水石膏的抗压强度提高的效果较差的问题。
发明人在研究中发现，用于制备α型半水石膏的多元有机酸中，丁二酸和戊二酸均为二元羧酸，丁二酸有良好的转晶作用，但丁二酸制备α-高强半水石膏到达低长径比和高强度时的用量很高。戊二酸的转晶效果较差，且强度相对于不掺转晶剂的α型半水石膏几乎没有区别。丁二酸和戊二酸的区别在于：丁二酸中羧基的间距为2个C原子，戊二酸中羧基的间距为3个C原子，有机酸转晶剂中羧基的间距会对转晶效果造成影响。故，发明人选取还没有人探究过的、在戊二酸结构的支链上增加一个羧基的丙三酸为转晶剂，使支链的羧基与主链的羧基均为2个C原子间隔，来制备α型高强半水石膏。
为了实现上述目的，本发明提供如下技术方案：一种α型半水石膏的制备方法，包括下述步骤：(1)使脱硫石膏悬浮液和丙三酸在120-140℃下反应3-5h；(2)固液分离，40-80℃真空干燥，即得α型半水石膏。
本发明还提供了一种α型半水石膏：α型半水石膏采用如上制备方法制备得到。α型半水石膏为短柱状晶体；α型半水石膏的长径比为(0.5-2.0):1。α型高强半水石膏的抗压强度＞35MPa。
有益效果：
本发明的α型半水石膏的制备方法通过采用丙三酸作为转晶剂，其仅含有三个羧基基团，且每两个相邻的羧基间距均为两个C原子，不含有复杂的无效基团，可使α高强石膏趋于径向发展，得到短柱状的α高强石膏晶体，增加α高强石膏的强度，有助于脱硫石膏的资源化利用。
本发明在转晶结束后，采用40-80℃干燥的方法获取α型高强半水石膏，有助于避免破坏α型高强半水石膏中的0.5个结晶水。
本发明制备方法简单、易操作，可以实现α型高强半水石膏的工业化生产。采用本发明制备方法制备得到的α型高强半水石膏呈短柱状，长径比可达1.0，烘干的抗压强度可达43.6MPa。
附图说明
图1为丙三酸的结构式；
图2为α型高强半水石膏的晶体形貌；
图3为实施例1提供的丙三酸的浓度为1.0mM时制备得到的α型高强半水石膏的光学显微图片；
图4为实施例1提供的丙三酸的浓度为1.5mM时制备得到的α型高强半水石膏的光学显微图片；
图5为实施例1提供的丙三酸的浓度为2.0mM时制备得到的α型高强半水石膏的光学显微图片；
图6为实施例1提供的丙三酸的浓度为2.5mM时制备得到的α型高强半水石膏的光学显微图片；
图7为实施例1提供的丙三酸的浓度为3.0mM时制备得到的α型高强半水石膏的光学显微图片；
图8为实施例1提供的丙三酸的浓度为3.5mM时制备得到的α型高强半水石膏的光学显微图片；
图9为实施例1提供的丙三酸的浓度为4.0mM时制备得到的α型高强半水石膏的光学显微图片；
图10为对比例1提供的不添加转晶剂时制备得到的产物的光学显微图片。
具体实施方式
本发明针对目前存在的以脱硫石膏为原料、采用常用有机酸转晶剂对脱硫石膏进行处理时，在α型半水石膏晶体的(111)面的吸附能的绝对值小、不易得到长径比为1:1的理想短柱状的α型半水石膏晶体或有机酸转晶剂对α型石膏的抗压强度提高的效果较差的问题，提供一种α型半水石膏的制备方法，本发明α型半水石膏抗压强度高性能好，即一种α型高强半水石膏的制备方法。
本发明实施例的α型高强半水石膏的制备方法包括下述步骤：(1)使脱硫石膏悬浮液和丙三酸在120-140℃下反应3-5h；(2)固液分离，40-80℃真 空干燥，即得α型高强半水石膏。
其中，当脱硫石膏悬浮液与丙三酸的反应温度低于120℃时，α型半水石膏的转化率低，成型后的强度低；若反应温度高于140℃，则会破坏α型半水石膏晶体的完整度，导致标准稠度用水量增高，强度降低。当反应时间低于3h，发现α型高强半水石膏的转化不充分，会有部分的二水石膏未能及时的发生反应，影响产物的强度。同时，在满足产物形貌和强度的条件下出于节能的考虑反应时间不宜高于5h。
本发明制备α型高强半水石膏的过程中，所采用的转晶剂为丙三酸(结构式如图1所示)，具有3个羧基基团，且相邻的2个羧基的间距均为2个C原子。该转晶剂能够在α型高强半水石膏(111)表面产生强烈的吸附作用，抑制α型高强半水石膏沿轴向的生长(α型高强半水石膏的晶体形貌如图2所示)，使α型高强半水石膏趋于径向发展，得到短柱状的α型高强半水石膏，增加α型高强半水石膏的强度，进而有助于脱硫石膏的资源化利用。此外，步骤(2)中，在固液分离后采用40-80℃的干燥温度，有助于防止由于温度过高，破坏α型高强半水石膏中0.5个结晶水，而影响α型高强半水石膏的强度。
优选，步骤(1)在搅拌条件下进行，搅拌转速为250-350r/min。搅拌转速过低会导致原料搅拌不均匀发生团聚现象，影响产物的转化和使用性能。搅拌转速过高会提高α半水石膏晶体之间的摩擦，导致长径比增大，强度降低。
优选，步骤(1)中，丙三酸与脱硫石膏悬浮液的混合物中，丙三酸的浓度为1-4mM。
优选，丙三酸的浓度为2.5-3.5mM，反应温度为130-140℃，反应时间为4-5h。
优选，脱硫石膏悬浮液采用脱硫石膏和水配制成；脱硫石膏悬浮液中，脱硫石膏的浓度为10-30wt％。脱硫石膏的浓度超过30wt％容易发生沉积，导致部分脱硫石膏未转化为半水石膏，影响产物的强度。
优选，步骤(1)之前还包括对脱硫石膏进行清洗和真空干燥(干燥至恒重)的步骤；清洗包括采用水对脱硫石膏进行洗涤的步骤；真空干燥的温度为40-60℃。通过对脱硫石膏进行水洗，可除去脱硫石膏中的不溶性的有机 物和碳酸钙杂质以及可溶性的氯离子杂质。
优选，步骤(2)中，固液分离时还包括采用无水乙醇作为水化抑制剂对所得固体产物进行洗涤的步骤。通过采用无水乙醇作为水化抑制剂，对固液分离(可采用抽滤机来实现固液分离)得到的固体进行反复洗涤，有助于防止新生成的α型高强半水石膏发生水化。实际工业生产中，如果固液分离与干燥之间的速度很快，这一步骤也可以省去。
优选，步骤(2)中，真空干燥的时间为20-24h。
本发明还提出了一种α型高强半水石膏，本发明实施例的α型高强半水石膏采用如上所述的方法制备得到。
优选，α型高强半水石膏为短柱状晶体；α型高强半水石膏的长径比为(0.5-2.0):1。
优选，α型高强半水石膏的长径比为(0.8-1.1):1。
优选，α型高强半水石膏的抗压强度＞35MPa。
优选，α型高强半水石膏的抗压强度＞40.5MPa。
下面通过具体实施例对本发明α型高强半水石膏及其制备方法进行详细说明。
下面实施例中：脱硫石膏取自河南省焦作市一火力发电厂，主要成分由CaSO 4·2H 2O组成，且含有少量的SiO 2和CaCO 3；分析纯丙三酸(C 6H 8O 6,99.0％)、戊二酸(C 5H 8O 4,99.0％)和丁二酸(C 6H 8O 7,99.7％)由上海麦克林生化科技有限公司生产；无水乙醇(CH 3CH 2OH,99.7％)由天津市河东区红岩试剂厂生产。
实施例1
本实施例的α型高强半水石膏的制备方法包括下述步骤：
(1)用清水对脱硫石膏进行清洗，抽滤并烘干至恒重；
(2)采用水和经步骤(1)清洗并干燥后的脱硫石膏按照固液比1:5的比例配制脱硫石膏悬浮液(脱硫石膏悬浮液中，脱硫石膏的浓度为20wt％，分别向7份上述脱硫石膏悬浮液中加入丙三酸转晶剂，使脱硫石膏悬浮液中丙三酸转晶剂的终浓度为1-4mM(以0.5mM为梯度)，放入反应釜中；
(3)密封反应釜，设置反应温度为130℃，搅拌速度为300r/min，恒温反应时间4h，完成二水石膏向α型高强半水石膏的转化；
(4)反应结束后，快速使用无水乙醇对产物进行洗涤，抽滤并在45℃的真空干燥箱中干燥24h，得到本实施例的α型高强半水石膏。
实施例2
本实施例按照下述方法对脱硫石膏进行处理，包括下述步骤：
(1)使用清水对脱硫石膏进行清洗，抽滤并烘干至恒重；
(2)采用水和经步骤(1)清洗并干燥后的脱硫石膏配制脱硫石膏悬浮液(脱硫石膏悬浮液中，脱硫石膏的浓度为10wt％)，向上述脱硫石膏悬浮液中加入丙三酸转晶剂，使脱硫石膏悬浮液中丙三酸转晶剂的终浓度为3mM，放入反应釜中；
(3)密封反应釜，设置反应温度为130℃，搅拌速度为300r/min，恒温反应时间4h，完成二水石膏向α型高强半水石膏的转化；
(4)反应结束后，快速使用无水乙醇对产物进行洗涤，抽滤并在45℃的真空干燥箱中干燥24h，得到本实施例的产物。
实施例3
本实施例按照下述方法对脱硫石膏进行处理，包括下述步骤：
(1)使用清水对脱硫石膏进行清洗，抽滤并烘干至恒重；
(2)采用水和经步骤(1)清洗并干燥后的脱硫石膏配制脱硫石膏悬浮液(脱硫石膏悬浮液中，脱硫石膏的浓度为30wt％)，向上述脱硫石膏悬浮液中加入丙三酸转晶剂，使脱硫石膏悬浮液中丙三酸转晶剂的终浓度为3mM，放入反应釜中；
(3)密封反应釜，设置反应温度为130℃，搅拌速度为300r/min，恒温反应时间4h，完成二水石膏向α型高强半水石膏的转化；
(4)反应结束后，快速使用无水乙醇对产物进行洗涤，抽滤并在45℃的真空干燥箱中干燥24h，得到本实施例的产物。
实施例4
本实施例按照下述方法对脱硫石膏进行处理，包括下述步骤：
(1)使用清水对脱硫石膏进行清洗，抽滤并烘干至恒重；
(2)采用水和经步骤(1)清洗并干燥后的脱硫石膏配制脱硫石膏悬浮液(脱硫石膏悬浮液中，脱硫石膏的浓度为20wt％)，向上述脱硫石膏悬浮液中加入丙三酸转晶剂，使脱硫石膏悬浮液中丙三酸转晶剂的终浓度为 3mM，放入反应釜中；
(3)密封反应釜，设置反应温度为120℃，搅拌速度为300r/min，恒温反应时间4h，完成二水石膏向α型高强半水石膏的转化；
(4)反应结束后，快速使用无水乙醇对产物进行洗涤，抽滤并在45℃的真空干燥箱中干燥24h，得到本实施例的产物。
实施例5
本实施例按照下述方法对脱硫石膏进行处理，包括下述步骤：
(1)使用清水对脱硫石膏进行清洗，抽滤并烘干至恒重；
(2)采用水和经步骤(1)清洗并干燥后的脱硫石膏配制脱硫石膏悬浮液(脱硫石膏悬浮液中，脱硫石膏的浓度为20wt％)，向上述脱硫石膏悬浮液中加入丙三酸转晶剂，使脱硫石膏悬浮液中丙三酸转晶剂的终浓度为3mM，放入反应釜中；
(3)密封反应釜，设置反应温度为140℃，搅拌速度为300r/min，恒温反应时间4h，完成二水石膏向α型高强半水石膏的转化；
(4)反应结束后，快速使用无水乙醇对产物进行洗涤，抽滤并在45℃的真空干燥箱中干燥24h，得到本实施例的产物。
实施例6
本实施例按照下述方法对脱硫石膏进行处理，包括下述步骤：
(1)使用清水对脱硫石膏进行清洗，抽滤并烘干至恒重；
(2)采用水和经步骤(1)清洗并干燥后的脱硫石膏配制脱硫石膏悬浮液(脱硫石膏悬浮液中，脱硫石膏的浓度为20wt％)，向上述脱硫石膏悬浮液中加入丙三酸转晶剂，使脱硫石膏悬浮液中丙三酸转晶剂的终浓度为3mM，放入反应釜中；
(3)密封反应釜，设置反应温度为130℃，搅拌速度为250r/min，恒温反应时间4h，完成二水石膏向α型高强半水石膏的转化；
(4)反应结束后，快速使用无水乙醇对产物进行洗涤，抽滤并在45℃的真空干燥箱中干燥24h，得到本实施例的产物。
实施例7
本实施例按照下述方法对脱硫石膏进行处理，包括下述步骤：
(1)使用清水对脱硫石膏进行清洗，抽滤并烘干至恒重；
(2)采用水和经步骤(1)清洗并干燥后的脱硫石膏配制脱硫石膏悬浮液(脱硫石膏悬浮液中，脱硫石膏的浓度为20wt％)，向上述脱硫石膏悬浮液中加入丙三酸转晶剂，使脱硫石膏悬浮液中丙三酸转晶剂的终浓度为3mM，放入反应釜中；
(3)密封反应釜，设置反应温度为130℃，搅拌速度为350r/min，恒温反应时间4h，完成二水石膏向α型高强半水石膏的转化；
(4)反应结束后，快速使用无水乙醇对产物进行洗涤，抽滤并在45℃的真空干燥箱中干燥24h，得到本实施例的产物。
实施例8
本实施例按照下述方法对脱硫石膏进行处理，包括下述步骤：
(1)使用清水对脱硫石膏进行清洗，抽滤并烘干至恒重；
(2)采用水和经步骤(1)清洗并干燥后的脱硫石膏配制脱硫石膏悬浮液(脱硫石膏悬浮液中，脱硫石膏的浓度为20wt％)，向上述脱硫石膏悬浮液中加入丙三酸转晶剂，使脱硫石膏悬浮液中丙三酸转晶剂的终浓度为3mM，放入反应釜中；
(3)密封反应釜，设置反应温度为130℃，搅拌速度为300r/min，恒温反应时间3h，完成二水石膏向α型高强半水石膏的转化；
(4)反应结束后，快速使用无水乙醇对产物进行洗涤，抽滤并在45℃的真空干燥箱中干燥24h，得到本实施例的产物。
实施例9
本实施例按照下述方法对脱硫石膏进行处理，包括下述步骤：
(1)使用清水对脱硫石膏进行清洗，抽滤并烘干至恒重；
(2)采用水和经步骤(1)清洗并干燥后的脱硫石膏，配制脱硫石膏悬浮液(脱硫石膏悬浮液中，脱硫石膏的浓度为20wt％)，向上述脱硫石膏悬浮液中加入丙三酸转晶剂，使脱硫石膏悬浮液中丙三酸转晶剂的终浓度为3mM，放入反应釜中；
(3)密封反应釜，设置反应温度为130℃，搅拌速度为300r/min，恒温反应时间5h，完成二水石膏向α型高强半水石膏的转化；
(4)反应结束后，快速使用无水乙醇对产物进行洗涤，抽滤并在45℃的真空干燥箱中干燥24h，得到本实施例的产物。
实施例10
本实施例按照下述方法对脱硫石膏进行处理，包括下述步骤：
(1)使用清水对脱硫石膏进行清洗，抽滤并烘干至恒重；
(2)采用水和经步骤(1)清洗并干燥后的脱硫石膏，配制脱硫石膏悬浮液(脱硫石膏悬浮液中，脱硫石膏的浓度为20wt％)，向上述脱硫石膏悬浮液中加入丙三酸转晶剂，使脱硫石膏悬浮液中丙三酸转晶剂的终浓度为3mM，放入反应釜中；
(3)密封反应釜，设置反应温度为130℃，搅拌速度为300r/min，恒温反应时间4h，完成二水石膏向α型高强半水石膏的转化；
(4)反应结束后，快速使用无水乙醇对产物进行洗涤，抽滤并在80℃的真空干燥箱中干燥24h，得到本实施例的产物。
对比例1
本对比例按照下述方法对脱硫石膏进行处理，包括下述步骤：
(1)使用清水对脱硫石膏进行清洗，抽滤并烘干至恒重；
(2)按照脱硫石膏和水的料浆浓度为20％的比例配制悬浮液；
(3)密封反应釜，设置反应温度为130℃，搅拌速度为300r/min，恒温反应时间4h，完成二水石膏向α型高强半水石膏的转化；
(4)反应结束后，快速使用无水乙醇对产物进行洗涤，抽滤并在45℃的真空干燥箱中干燥24h，得到本对比例的产物。
对比例2
本对比例按照下述方法对脱硫石膏进行处理，包括下述步骤：
(1)使用清水对脱硫石膏进行清洗，抽滤并烘干至恒重；
(2)按照脱硫石膏和水的料浆浓度为20％的比例配制悬浮液，同时配制3mM的戊二酸转晶剂放入反应釜中；
(3)密封反应釜，设置反应温度为130℃，搅拌速度为300r/min，恒温反应时间4h，完成二水石膏向α型高强半水石膏的转化；
(4)反应结束后，快速使用无水乙醇对产物进行洗涤，抽滤并在45℃的真空干燥箱中干燥24h，得到本对比例的产物。
对比例3
本对比例按照下述方法对脱硫石膏进行处理，包括下述步骤：
(1)使用清水对脱硫石膏进行清洗，抽滤并烘干至恒重；
(2)按照脱硫石膏和水的料浆浓度为20％的比例配制悬浮液，同时配制9mM的丁二酸转晶剂放入反应釜中；
(3)密封反应釜，设置反应温度为130℃，搅拌速度为300r/min，恒温反应时间4h，完成二水石膏向α型高强半水石膏的转化；
(4)反应结束后，快速使用无水乙醇对产物进行洗涤，抽滤并在45℃的真空干燥箱中干燥24h，得到本对比例的产物。
其中，经多次实验验证，当步骤(2)中丁二酸的浓度为9mM时，转晶效果最好；故本对比例将丁二酸转晶剂的浓度设置为9mM。
对比例4
本对比例与实施例1(丙三酸转晶剂的终浓度为3mM)的区别仅在于：步骤(3)中的反应温度为160℃；其余均与实施例1保持一致。
对比例5
本对比例与实施例1(丙三酸转晶剂的终浓度为3mM)的区别仅在于：步骤(3)中的搅拌速度为400r/min；其余均与实施例1保持一致。
对比例6
本对比例与实施例1(丙三酸转晶剂的终浓度为3mM)的区别仅在于：步骤(3)中的搅拌速度为450r/min；其余均与实施例1保持一致。
对比例7
本对比例与实施例1(丙三酸转晶剂的终浓度为3mM)的区别仅在于：步骤(3)中的搅拌速度为500r/min；其余均与实施例1保持一致。
对比例8
本对比例与实施例1(丙三酸转晶剂的终浓度为3mM)的区别仅在于：步骤(4)中，真空干燥的温度为100℃，其余均与实施例1保持一致。
对比例9
本对比例与实施例1(丙三酸转晶剂的终浓度为3mM)的区别仅在于：步骤(4)中，真空干燥的温度为120℃，其余均与实施例1保持一致。
对比例10
本对比例与实施例1(丙三酸转晶剂的终浓度为3mM)的区别仅在于：步骤(4)中，真空干燥的温度为140℃，其余均与实施例1保持一致。
实验例
1、采用第一性原理模拟计算与柠檬酸、戊二酸、丁二酸和丙三酸吸附在平行于c轴的(110)和(010)面和垂直于c轴的(111)面的吸附能，模拟计算的步骤如下：
(1)选择α半水石膏和转晶剂的模型；
(2)采用Materials Studio 2019软件对α型高强半水石膏的模型进行切面并与转晶剂组成相应的构型；
(3)通过改变截断能和收敛步数，分别对α型高强半水石膏表面模型、转晶剂模型和表面与转晶剂组成的构型进行结构优化，直至优化后的能量变化小于1KJ/mol。
(4)吸附能的计算为：构型的能量-α型高强半水石膏表面能量-转晶剂的能量。具体结果如下表1所示：
表1.柠檬酸、戊二酸、丁二酸和丙三酸在α型高强半水石膏(110)、(010)和(111)面的吸附能
Figure PCTCN2022129177-appb-000001
由上表1可知：柠檬酸、戊二酸、丁二酸和丙三酸在α型高强半水石膏晶体(111)面的吸附能分别为-100KJ/mol、-135KJ/mol、-121KJ/mol和-183KJ/mol。戊二酸在α高强石膏(010)面的吸附能的绝对值最大为-389KJ/mol，说明戊二酸优先吸附在(010)面其转晶效果不佳。柠檬酸、丁二酸和丙三酸在α型高强半水石膏(111)表面的吸附能为负值且绝对值均大于(010)和(110)面，说明这三种转晶剂均优先吸附在α型高强半水石膏(111)表面，具有良好的转晶效果。并且，丙三酸在α高强半水石膏(111)表面吸附能的绝对值相比于柠檬酸、丁二酸和戊二酸更大，转晶效果更好。
2、对上述实施例1及对比例1-2制备得到的α型高强半水石膏的长径比和烘干抗压强度(参照JC/T 2038-2010(α-型高强石膏)中的相应方法)进行测 试(测试样品粉磨至200目以细)。晶体的长径比测试方法包括如下步骤：
(1)采用超景深显微镜(Leica Company,Germany)进行形态学观察和图像采集；
(2)将样本图像导入测量软件Nano Measurer中，设定软件的测量尺寸，手动选择50个α半水石膏晶体测量长度和直径。
(3)将测量数据导入Excel表进行统计，计算出晶体的长径比。
实验结果如下表2所示：
表2实施例1及对比例1-12制备的α型高强半水石膏晶体的长径比和烘干抗压强度
样品 转晶剂-浓度 晶体的长径比 烘干抗压强度(MPa)
实施例1 丙三酸-1.0mM 1.7:1 35.3
实施例1 丙三酸-1.5mM 1.3:1 38.6
实施例1 丙三酸-2.0mM 1.2:1 39.2
实施例1 丙三酸-2.5mM 1.1:1 40.9
实施例1 丙三酸-3.0mM 1.0:1 43.6
实施例1 丙三酸-3.5mM 0.8:1 42.1
实施例1 丙三酸-4.0mM 0.7:1 36.9
/ 区别反应条件 / /
实施例2 脱硫石膏10wt％ 0.8:1 39.2
实施例3 脱硫石膏30wt％ 1.8:1 37.4
实施例4 反应温度120℃ 2.0:1 35.1
实施例5 反应温度140℃ 1.3:1 42.4
实施例6 搅拌转速250r/min 1.5:1 37.6
实施例7 搅拌转速350r/min 1.5:1 37.8
实施例8 反应时间3h 1.8:1 35.8
实施例9 反应时间5h 1.0:1 43.5
实施例10 80℃干燥 1.0:1 43.2
对比例1 不添加转晶剂 10.2:1 10.5
对比例2 戊二酸-3mM 8.9:1 11.1
对比例3 丁二酸-9mM 1.2:1 40.1
对比例4 反应温度160℃ 2.8:1 32.5
对比例5 搅拌转速400r/min 2.0:1 35.0
对比例6 搅拌转速450r/min 2.6:1 30.0
对比例7 搅拌转速500r/min 3.3:1 26.2
对比例8 100℃干燥 1.0:1 42.9
对比例9 120℃干燥 1.0:1 42.3
对比例10 140℃干燥 1.0:1 41.2
由表2可知：实施例1采用不同浓度的丙三酸作为转晶剂时，从α型高强半水石膏的烘干抗压强度的结果可以看出：掺入的丙三酸浓度在1.0～3.0mM范围内，α型高强石膏的烘干抗压强度随着丙三酸浓度的增加而提高。当丙三酸的浓度大于3.0mM时，其对α型高强石膏的烘干抗压强度的增强起着相反的作用。随着丙三酸浓度的增加α型高强石膏晶体的长径比越来越低，当达到长径比为1:1的理想型晶体时其烘干抗压强度最大。相比于不掺丙三酸转晶剂的对比例1和采用3mM的戊二酸和9mM的丁二酸作为转晶剂的对比例2、3，本发明的转晶剂对制备α型高强石膏具有显著的积极效果。
结合实施例1-3可知，脱硫石膏的浓度会对其向α型高强半水石膏转化的效果造成影响，可能的原因为：当脱硫石膏的浓度超过20wt％时，容易发生沉积，导致部分脱硫石膏未转化为半水石膏，进而影响产物的强度。
结合实施例1、实施例4-5及对比例4可知，当反应温度为120℃时，α型高强半水石膏的转化率低，成型后的强度低；温度高于140℃(例如160℃)会破坏α半水石膏晶体的完整度，导致标准稠度用水量增高，强度降低。
结合实施例1、实施例6和7及对比例5-7可知，搅拌转速过低会导致原料搅拌不均匀发生团聚现象，影响产物的转化和使用性能。搅拌转速过高会提高α型高强半水石膏晶体之间的摩擦，导致长径比增大，强度降低。
实施例1、实施例8和9说明了当反应时间为3h时，α型高强半水石膏的转化不充分，会有部分的二水石膏未能及时的发生反应影响产物的强度。同时，在满足产物形貌和强度的条件下出于节能的考虑反应时间不宜高于5h。
结合实施例1、实施例10和对比例8-10可知，随着干燥温度的升高， 制备得到的α型高强半水石膏的抗压强度逐渐减小，应尽量选择较低的干燥温度以避免破坏α型高强半水石膏中的0.5个结晶水。

Claims (8)

  1. 一种α型半水石膏制备方法，其特征在于，包括下述步骤：(1)使脱硫石膏悬浮液和丙三酸在120-140℃下反应3-5h；(2)固液分离，40-80℃真空干燥，即得所述α型半水石膏。
  2. 根据权利要求1所述的α型半水石膏制备方法，其特征在于，步骤(1)在搅拌条件下进行，搅拌转速为250-350r/min。
  3. 根据权利要求1所述的α型半水石膏制备方法，其特征在于，步骤(1)中，所述丙三酸与所述脱硫石膏悬浮液的混合物中，所述丙三酸的浓度为1-4mM；反应温度为130-140℃，反应时间为4-5h。
  4. 根据权利要求1所述的α型半水石膏制备方法，其特征在于，所述脱硫石膏悬浮液采用脱硫石膏和水配制而成；
    所述脱硫石膏悬浮液中，脱硫石膏的浓度为10-30wt％。
  5. 根据权利要求1所述的α型半水石膏制备方法，其特征在于，步骤(1)之前还包括对所述脱硫石膏进行清洗和真空干燥的步骤；
    所述清洗包括用水对所述脱硫石膏进行洗涤的步骤；
    所述真空干燥的温度为40-60℃。
  6. 根据权利要求1所述的α型半水石膏制备方法，其特征在于，步骤(2)中，固液分离时还包括采用无水乙醇作为水化抑制剂对所得固体产物进行洗涤的步骤。
  7. 根据权利要求1所述的α型半水石膏制备方法，其特征在于，步骤(2)中，所述真空干燥的时间为20-24h。
  8. 一种α型半水石膏，其特征在于，所述α型半水石膏采用如权利要求1-7任一项所述的制备方法制备得到；所述α型半水石膏为短柱状晶体；
    所述α型半水石膏的长径比为(0.5-2.0):1；所述α型半水石膏的抗压强度＞35MPa。
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1192142A (ja) * 1997-09-24 1999-04-06 Noritake Co Ltd α型半水石膏の製造方法
CN101734871A (zh) * 2008-11-18 2010-06-16 北京建筑材料科学研究总院有限公司 利用脱硫石膏制备α半水石膏
JP2012116147A (ja) * 2010-12-02 2012-06-21 Eidai Co Ltd 石膏硬化体の製造方法及び石膏硬化体
CN103951297A (zh) * 2014-04-16 2014-07-30 唐永波 α型超高强石膏的制备方法
CN113087423A (zh) * 2021-04-22 2021-07-09 深圳市青青源科技有限公司 一种用天然石膏恒定加压制备超高强石膏粉的方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19908776C2 (de) * 1999-02-19 2002-05-23 Ver Energiewerke Ag Verfahren und Anordnung zur Herstellung von hochreinem alpha-Calciumsulfat-Halbhydrat
CN101333086B (zh) * 2008-07-24 2010-09-01 东南大学 用脱硫二水石膏制备α型半水石膏浆及石膏制品的方法
CN105948547B (zh) * 2016-07-12 2017-10-31 山东博瑞新材料科技有限公司 一种利用二水硫酸钙制备α型半水硫酸钙的方法
CN114349039B (zh) * 2021-12-01 2023-08-18 湖南科技大学 一种在溶液体系中调控α-半水石膏晶体形貌和粒度的方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1192142A (ja) * 1997-09-24 1999-04-06 Noritake Co Ltd α型半水石膏の製造方法
CN101734871A (zh) * 2008-11-18 2010-06-16 北京建筑材料科学研究总院有限公司 利用脱硫石膏制备α半水石膏
JP2012116147A (ja) * 2010-12-02 2012-06-21 Eidai Co Ltd 石膏硬化体の製造方法及び石膏硬化体
CN103951297A (zh) * 2014-04-16 2014-07-30 唐永波 α型超高强石膏的制备方法
CN113087423A (zh) * 2021-04-22 2021-07-09 深圳市青青源科技有限公司 一种用天然石膏恒定加压制备超高强石膏粉的方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PENG JIA-HUI,CHEN MING-FENG,ZHANG JIAN-XIN,QU JIN-DONG,ZOU CHEN-YANG: "Influnce of Organic Acid Structure on Crystal Morphology of α-hemihydrate Desulfurization Gypsum and Its Crystal Modification Mechanism", JOURNAL OF SICHUAN UNIVERSITY(ENGINEERING SCIENCE EDITION), vol. 44, no. 1, 20 January 2012 (2012-01-20), pages 166 - 172, XP093075712, ISSN: 2096-3246, DOI: 10.15961/j.jsuese.2012.01.008 *

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