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Dihydrate gypsum and preparation method thereof

A technique of dihydrate gypsum and anhydrite, applied in the field of dihydrate gypsum, can solve the problems of increasing dihydrate gypsum, increasing nitrogen content and high process cost

Inactive Publication Date: 2020-05-19
JIANGSU EFFUL SCIENCE AND TECHNOLOGY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, in the hydration process of anhydrite (calcium sulfate anhydrous), the main method to increase the particle size of calcium sulfate dihydrate through intervention measures is to add large particles of calcium sulfate dihydrate seed crystals to make the Ca in the saturated solution 2+ and After precipitation, grow directly on the surface of the seed crystal; through the principle of crystal dissolution-crystallization, a series of parameters such as feeding speed, stirring speed, and temperature are intuitively controlled to control the size of the crystal, but these methods are complicated and operate under harsh conditions
CN110128045A discloses an activator for rapid hydration of type II anhydrite and a rapid hydration method that use 20% to 50% of the anhydrite quality dihydrate gypsum seed crystals to significantly increase the size of the dihydrate gypsum particles. However, the amount of dihydrate gypsum added is relatively large, and when the amount of dihydrate gypsum seed crystals is too much, it is impossible to directly determine the reason for the increase of dihydrate gypsum particles after hydration
CN106395879A discloses a method for preparing calcium sulfate dihydrate with large particle size in wet-process phosphoric acid process, the method is formed by adding sulfonic acid regulator, organic weak acid and its ammonium salt buffer and water-soluble polymer dispersant Composite aqueous solution is used to increase the size of calcium sulfate dihydrate in the wet-process phosphoric acid process. Although the addition of the composite aqueous solution is 0.005-3% of the mass fraction of the phosphate rock raw material, the formulation of the composite aqueous solution is complex and involves various ammonium salts. Excessive use will lead to an increase in nitrogen content, which is harmful to the human body, and it needs to be added in three steps to effectively increase the particle size of dihydrate gypsum, resulting in higher process costs

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Experimental program
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Embodiment 1

[0046] The present embodiment provides a kind of method for preparing dihydrate gypsum, described method comprises the steps:

[0047] First configure 7.931×10 respectively -9 mol / L, 7.931×10 -5 mol / L and 7.931×10 -4 mol / L of citric acid solution, get 100 parts specific surface area is 550m 2Fluorogypsum / kg, 5 parts of calcined alum, 5.8 parts of sodium sulfate, 29.5 parts of sodium chloride and citric acid solutions with different concentrations of 6 times the weight of anhydrite were put into the reactor, and stirred at 25°C and 200r / min for 24h. Obtain dihydrate gypsum;

[0048] Among them, after the set hydration end point is reached, the hydration product is terminated with absolute ethanol, filtered with fast filter paper, washed with absolute ethanol for 3 times, dried in a vacuum oven at 50°C to constant weight, and its crystallization is measured. According to the water content, the hydration rate of dihydrate gypsum corresponding to the calculation of different c...

Embodiment 2

[0050] The present embodiment provides a kind of method for preparing dihydrate gypsum, described method comprises the steps:

[0051] First configure 5.4×10 -8 mol / L, 5.4×10 -7 mol / L and 5.4×10 -4 mol / L sodium trimetaphosphate solution, take 101 parts specific surface is 600m 2 Fluorogypsum / kg, 4.8 parts of calcined alum, 5.9 parts of sodium sulfate, 30 parts of sodium chloride and 6 times the weight of anhydrite sodium trimetaphosphate solution are put into the reactor, stirred at 25°C and 190r / min for 24h to obtain Dihydrate gypsum;

[0052] Among them, after the set hydration end point is reached, the hydration product is terminated with absolute ethanol, filtered with fast filter paper, washed with absolute ethanol for 3 times, dried in a vacuum oven at 50°C to constant weight, and its crystallization is measured. According to the water content, the hydration rates of dihydrate gypsum obtained by calculating different concentrations of sodium trimetaphosphate solution...

Embodiment 3

[0054] The present embodiment provides a kind of method for preparing dihydrate gypsum, described method comprises the steps:

[0055] First configure 8.09×10 respectively -9 mol / L, 8.09×10 -7 mol / L and 8.09×10 -5 mol / L of hydroxyethylidene diphosphonic acid solution, get 103 parts of specific surface area is 650m 2 / kg fluorine gypsum, 5.5 parts of calcined alum, 6 parts of sodium sulfate, 30.2 parts of sodium chloride and 6.6 times the weight of anhydrite were put into the reactor, and stirred at 30°C and 200r / min for 24h, Obtain dihydrate gypsum;

[0056] Among them, after the set hydration end point is reached, the hydration product is terminated with absolute ethanol, filtered with fast filter paper, washed with absolute ethanol for 3 times, dried in a vacuum oven at 50°C to constant weight, and its crystallization is measured. According to the water content, the hydration rates of the corresponding dihydrate gypsum were calculated according to different concentration...

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Abstract

The invention relates to dihydrate gypsum and a preparation method thereof. The dihydrate gypsum comprises the following raw materials: anhydrite, alum, sodium salt and an aqueous solution. Accordingto the method disclosed by the invention, the dihydrate gypsum with relatively large particles can be simply and conveniently prepared under the condition of adding a small amount of aqueous solution,and the addition of the aqueous solution hardly influences the later application of the product; the maximum hydration rate of the obtained dihydrate gypsum can reach 93.4%, and the maximum median diameter of the obtained dihydrate gypsum can reach 21.88 mum.

Description

technical field [0001] The invention relates to the field of dihydrate gypsum, in particular to a dihydrate gypsum and a preparation method thereof. Background technique [0002] Anhydrous calcium sulfate is anhydrous calcium sulfate. Its gelling properties are poor. In industrial production, anhydrite is generally converted into dihydrate gypsum for use. Anhydrite is converted into dihydrate gypsum when it meets water. This is a spontaneous process. , but the generated dihydrate gypsum particles are flaky, rod-shaped, needle-shaped, and the particles are also large and small. Different sizes often limit the use of dihydrate gypsum. The production of β hemihydrate gypsum (building gypsum) and α hemihydrate gypsum (high strength gypsum) from dihydrate gypsum requires different conditions, but both have requirements for the particle size of dihydrate gypsum, and the particle size is too small, such as below 10μm Dihydrate gypsum greatly limits its application. Therefore, it ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B11/26C04B11/06
CPCC04B11/06C04B11/262
Inventor 陈甜甜陈靓唐永波
Owner JIANGSU EFFUL SCIENCE AND TECHNOLOGY CO LTD