Method for regulating crystal morphology and granularity of alpha-semi-hydrated gypsum in solution system

A hemihydrate gypsum and system technology, applied in chemical instruments and methods, inorganic chemistry, calcium/strontium/barium compounds, etc., can solve the problems of few, unable to generate carboxylate ions, and unable to effectively control the morphology of phase change products, etc. , to achieve the effects of short time, control of crystal particle size and reduction of influence

Active Publication Date: 2022-04-15
HUNAN UNIV OF SCI & TECH
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Problems solved by technology

However, the acidic solution environment often inhibits the dissociation of carboxylic acid-based crystallization agents, and cannot produce carboxylate ions complexed with calcium ions. Therefore, such crystallization agents in inorganic acid solution systems often do not work, that is to say Although dihydrate gypsum can be transformed into α-hemihydrate gypsum in inorganic acid solution under atmospheric pressure, the morphology of the phase transition product cannot be effectively controlled.
On the other hand, the crystal size of α-hemihydrate gypsum has a great influence on the strength of gypsum gel, but there are few effective methods for controlling the crystal size of α-hemihydrate gypsum

Method used

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  • Method for regulating crystal morphology and granularity of alpha-semi-hydrated gypsum in solution system
  • Method for regulating crystal morphology and granularity of alpha-semi-hydrated gypsum in solution system
  • Method for regulating crystal morphology and granularity of alpha-semi-hydrated gypsum in solution system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] Prepare a sodium chloride solution with a mass fraction of 25%, add desulfurized gypsum (the mass fraction of dihydrate gypsum is 92%) to it according to the solid-to-liquid ratio of 1:4 and mix to form a gypsum suspension, and then add the gypsum suspension to the phase In the variable reactor, add 15×10 -4 mol / kg sodium succinate, react at 95°C for 2h, then filter while hot, wash the separated solid phase with boiling water and transfer to an oven at 60°C to dry to constant weight to obtain α-hemihydrate gypsum seed crystals Such as figure 1 As shown, the average length is about 7.56 μm, the average diameter is about 15.94 μm, and the average aspect ratio is about 0.48.

[0054] Prepare the hydrochloric acid solution of 0.4mol / L, add sodium chloride thereinto, form the mixed solution that the mass fraction of sodium chloride is 15%, the concentration of hydrochloric acid is 0.4mol / L, the mixed solution is joined in the phase change reactor, reaction temperature Set ...

Embodiment 2

[0058] Prepare an aqueous solution of glycerol with a mass fraction of 45%, add desulfurized gypsum (dihydrate gypsum mass fraction of 92%) to it according to the solid-to-liquid ratio of 1:3 and mix to form a gypsum suspension, and then add the gypsum suspension to the phase change reaction In the device, add 15×10 at the same time -4 mol / kg sodium succinate, react at 95°C for 2h, then filter while hot, wash the separated solid phase with boiling water and transfer to an oven at 60°C to dry to constant weight to obtain α-hemihydrate gypsum seed crystals Such as Figure 4 As shown, the average length is about 16.34 μm, the average diameter is about 16.63 μm, and the average aspect ratio is about 1.02.

[0059] Prepare the hydrochloric acid solution of 0.6mol / L, add sodium chloride thereinto, form the mixed solution that the mass fraction of sodium chloride is 20%, the concentration of hydrochloric acid is 0.6mol / L, the mixed solution is joined in the phase change reactor, rea...

Embodiment 3

[0066] Prepare a potassium chloride solution with a mass fraction of 15%, add dihydrate gypsum (analytical pure) to it according to the solid-to-liquid ratio of 1:4 and mix to form a gypsum suspension, then add the gypsum suspension to the phase change reactor, Simultaneously join 1.5×10 -4 mol / kg sodium citrate, reacted at 95°C for 2h, then filtered while hot, and the separated solid phase was washed with boiling water and transferred to an oven at 60°C to dry to constant weight to obtain α-hemihydrate gypsum seed crystals such as Figure 10 As shown, the average length is about 29.08 μm, the average diameter is about 16.31 μm, and the average aspect ratio is about 1.76.

[0067] Prepare a 1.2mol / L sulfuric acid solution, add sodium sulfate thereto to form a mixed solution with a mass fraction of sodium sulfate of 10% and a sulfuric acid concentration of 1.2mol / L, add the mixed solution to the phase change reactor, and set the reaction temperature When the temperature of th...

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Abstract

The invention relates to a method for regulating and controlling the morphology and granularity of alpha-semi-hydrated gypsum crystals by adding seed crystals. According to the invention, crystal morphology and granularity of alpha-semi-hydrated gypsum generated in a solution system are regulated and controlled by adding a seed crystal, wherein the seed crystal is alpha-semi-hydrated gypsum, and the long diameter of the seed crystal is less than or equal to 2.5. The average crystal length of the alpha-semi-hydrated gypsum product is 30-100 [mu] m, the average width is 15-30 [mu] m, and the average length-diameter ratio is 1.0-6.0. Meanwhile, the obtained product is high in purity and high in strength. The method is simple and controllable in process, and the obtained product is excellent in performance and convenient for large-scale application.

Description

technical field [0001] The invention relates to a method for regulating the crystal morphology and particle size of α-hemihydrate gypsum by adding crystal seeds, in particular to a method for preparing high-strength gypsum by adding crystal seeds in an acidic solution. Background technique [0002] The crystals of α-hemihydrate gypsum are hexagonal bipyramid columns with complete crystal development and dense structure. Among them, α-hemihydrate gypsum with short columnar shape and large particle size, which is commonly referred to as high-strength gypsum, has a standard consistency with low water demand and heat of hydration. Small size and high mechanical strength are widely used in ceramic abrasives, precision casting, dental superhydrite and arts and crafts and other fields. [0003] At present, industrial by-product gypsum (such as phosphogypsum, desulfurized gypsum, titanium gypsum, etc.) has gradually replaced natural gypsum ore as the main raw material for the produc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F11/46
CPCC01F11/466C01P2002/60C01P2004/61
Inventor 管青军余伟健眭滢卜勇杰曾楚雄刘楚峰王平解波
Owner HUNAN UNIV OF SCI & TECH
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