Microwave preparation method of alpha-calcium sulfate hemihydrate

A technology of calcium sulfate hemihydrate and calcium sulfate dihydrate, which is applied in the field of preparation of α-calcium sulfate hemihydrate, can solve the problems of multiple impurities, low added value, high free water, etc., and achieve the effect of shortening the reaction time

Active Publication Date: 2017-02-22
SOUTH CHINA UNIV OF TECH +1
9 Cites 5 Cited by

AI-Extracted Technical Summary

Problems solved by technology

The main component of this salt gypsum is the same as natural gypsum, which is calcium sulfate dihydrate, but it has relatively high free water and more impurities. Its comprehensive utilization methods mainly include: ① Used ...
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Abstract

The invention discloses a microwave preparation method of alpha-calcium sulfate hemihydrate. The method includes the steps of: adding calcium sulphate dehydrate into an aqueous solution containing calcium chloride and sodium chloride, carrying out microwave heating reaction under the action of ultrasound, and conducting filtering, washing and drying to obtain alpha-calcium sulfate hemihydrates. The method provided by the invention is characterized in that it utilizes the synergistic effect of microwave and ultrasonic wave to accelerate the reaction rate and reduce the reaction time, and the prepared alpha-calcium sulfate hemihydrates crystal is a fibrous structure, and has uniform shape and size and high crystallinity.

Technology Topic

Aqueous solutionCalcium Sulfate Hemihydrate +8

Image

  • Microwave preparation method of alpha-calcium sulfate hemihydrate
  • Microwave preparation method of alpha-calcium sulfate hemihydrate
  • Microwave preparation method of alpha-calcium sulfate hemihydrate

Examples

  • Experimental program(7)

Example Embodiment

[0028] Example 1
[0029] Add 5.0g calcium sulfate dihydrate and 100mL mixed salt solution (calcium chloride 100g/L, sodium chloride 50g/L) to the reaction vessel, put it into the CW-2000 ultrasonic/microwave collaborative extraction/reactor, and set the procedure: Under the combined action of ultrasonic waves and microwaves, the reaction system was heated to 105°C at a heating rate of 4°C/min, and then maintained at a constant temperature for 2 h; immediately after the reaction, the reaction mixture was filtered and washed, and the solid product was placed in a 60°C oven to dry 19h, obtained α-calcium sulfate hemihydrate.
[0030] figure 2 is the scanning electron microscope image of the prepared α-calcium sulfate hemihydrate, obtained from figure 2 It can be seen that the obtained α-calcium sulfate hemihydrate has a uniform fibrous structure with an average length of 112.9 μm and an average diameter of 7.37 μm.

Example Embodiment

[0031] Example 2
[0032] Add 5.0g calcium sulfate dihydrate and 100mL mixed salt solution (calcium chloride 100g/L, sodium chloride 50g/L) to the reaction vessel, put it into the CW-2000 ultrasonic/microwave collaborative extraction/reactor, and set the procedure: Under the combined action of ultrasonic waves and microwaves, the reaction system was heated to 105°C at a heating rate of 8°C/min, and then maintained at a constant temperature for 3 hours; immediately after the reaction, the reaction mixture was filtered and washed, and the solid product was placed in a 60°C oven Dry for 12h to obtain α-calcium sulfate hemihydrate.
[0033] image 3 is the scanning electron microscope image of the prepared α-calcium sulfate hemihydrate, by image 3 It can be seen that the obtained α-calcium sulfate hemihydrate has a uniform fibrous structure with an average length of 113.78 μm and an average diameter of 8.31 μm.
[0034] Figure 4 is the XRD pattern of the obtained α-calcium sulfate hemihydrate, obtained by Figure 4 It can be seen that the prepared α-calcium sulfate hemihydrate has a very sharp XRD diffraction peak, and the phase search analysis shows that the sample is relatively pure and has a high degree of crystallinity.
[0035] The obtained α-calcium sulfate hemihydrate crystal XRD pattern of each peak index and crystallinity data are shown in Table 1.
[0036] Each peak index and crystallinity data of XRD pattern of α-calcium sulfate hemihydrate crystal prepared in Table 1
[0037]
[0038] It is known from Table 1 that the crystallinity of the obtained α-calcium sulfate hemihydrate crystals is 96.88%.

Example Embodiment

[0039] Example 3
[0040] Add 8.0g calcium sulfate dihydrate and 100mL mixed salt solution (calcium chloride 80g/L, sodium chloride 50g/L) to the reaction vessel, put it into the CW-2000 ultrasonic/microwave collaborative extraction/reactor, and set the procedure: Under the combined action of ultrasonic waves and microwaves, the reaction system was heated to 105°C at a heating rate of 2°C/min, and then maintained at a constant temperature for 3 hours; immediately after the reaction, the reaction mixture was filtered and washed, and the solid product was placed in a 60°C oven. Dry for 18h to obtain α-calcium sulfate hemihydrate. The obtained α-calcium sulfate hemihydrate crystal has a uniform fibrous structure, with an average crystal length of 110.78 μm and an average diameter of 7.31 μm.

PUM

PropertyMeasurementUnit
Average length113.0µm
The average diameter7.37µm
Average length114.0µm

Description & Claims & Application Information

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