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Method for preparing alpha semi-hydrated gypsum by utilizing desulfurized gypsum

A technology of hemihydrate gypsum and desulfurized gypsum, which is applied in the field of producing α hemihydrate gypsum and preparing α hemihydrate gypsum, achieving the effects of wide source of raw materials, stable product performance and simple process

Inactive Publication Date: 2010-06-16
BEIJING BUILDING MATERIALS ACADEMY OF SCI RES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These methods draw on the natural gypsum production of α hemihydrate gypsum, but all ignore the influence of dihydrate gypsum taste and impurities in desulfurized gypsum on the production of α hemihydrate gypsum

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Add the desulfurized gypsum into the mixing tank and add water to stir, and prepare a slurry with a solid content rate of 10%, add 1M dilute sulfuric acid until the solution is weakly acidic (pH=5), remove insoluble oxides, calcium carbonate, and magnesium carbonate, and simultaneously The organic carbon is filtered out to obtain relatively pure desulfurized gypsum slurry. Add water to the purified desulfurized gypsum slurry to prepare a slurry with a solid content rate of 5%, enter the reaction tank A, add a crystal-transforming agent with a mass of 1% of the slurry, and in the crystal-transforming agent, aluminum sulfate accounts for 47.5%, aluminum potassium sulfate 47.5%, Potassium sodium tartrate 5%, heat the desulfurized gypsum slurry in reaction tank A to 93°C under normal pressure, maintain the temperature for 8 hours, complete the conversion of dihydrate gypsum to α hemihydrate gypsum crystals, and convert the converted α hemihydrate gypsum crystal slurry Trans...

Embodiment 2

[0019] Add the desulfurized gypsum into the mixing tank and add water to stir, and prepare a slurry with a solid content rate of 10%, add 1M dilute sulfuric acid until the solution is weakly acidic (pH=5), remove insoluble oxides, calcium carbonate, and magnesium carbonate, and simultaneously The organic carbon is filtered out to obtain relatively pure desulfurized gypsum slurry. Add water to the purified desulfurized gypsum slurry to prepare a slurry with a solid content rate of 5%, enter the reaction tank A, add a crystal-transforming agent with a mass of 1% of the slurry, and in the crystal-transforming agent, potassium aluminum sulfate accounts for 95% and potassium sodium tartrate 5%. , heat the desulfurized gypsum slurry in reaction tank A to 93°C under normal pressure, and maintain the temperature for 8 hours to complete the conversion of dihydrate gypsum to α hemihydrate gypsum crystals, and transfer the converted α hemihydrate gypsum crystal slurry to reaction tank B ...

Embodiment 3

[0021] Add the desulfurized gypsum into the mixing tank and add water to stir, and prepare a slurry with a solid content rate of 10%, add 1M dilute sulfuric acid until the solution is weakly acidic (pH=5), remove insoluble oxides, calcium carbonate, and magnesium carbonate, and simultaneously The organic carbon is filtered out to obtain relatively pure desulfurized gypsum slurry. Add water to the purified desulfurized gypsum slurry to prepare a slurry with a solid content rate of 5%, enter the reaction tank A, add a crystal-transforming agent with a mass of 1% of the slurry, and in the crystal-transforming agent, sodium citrate accounts for 40% and potassium aluminum sulfate accounts for 55%. , Potassium Sodium Tartrate 5%, heat the desulfurized gypsum slurry in reaction tank A to 93°C under normal pressure, maintain the temperature for 8 hours, complete the conversion of dihydrate gypsum to α hemihydrate gypsum crystals, and convert the converted α hemihydrate gypsum crystals ...

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Abstract

The invention provides a method for preparing alpha semi-hydrated gypsum by utilizing desulfurized gypsum, comprising the technological steps of purification, crystal transforming reaction, oriented crystallization, washing and separation, and drying and pulverization. The method concretely comprises the following steps of: enhancing the taste of calcium sulfate dlhy in the desulfurized gypsum to be greater than 95% through a purification treatment; dissolving and recrystallizing the desulfurized gypsum at 70 to 98 DEG C under the normal pressure through adding prepared habit modifiers, transforming into the alpha semi-hydrated gypsum and then carrying out oriented crystallization on the alpha semi-hydrated gypsum to form a short column-shaped alpha semi-hydrated gypsum crystal under the function of an oriented crystal type stabilizer, wherein the length-diameter ratio of the short column-shaped alpha semi-hydrated gypsum crystal is less than 1:3, the 2h breaking strength is greater than 6.5 MPa, the compression strength is greater than 23 MPa, the dry breaking strength is greater than 25 MPa, and the dry compression strength is greater than 53 MPa. The method can be widely used in the fields of ceramics, automobiles, precise casting, heterogenic casting and the like.

Description

Technical field [0001] The invention relates to the technical field of producing alpha hemihydrate gypsum, in particular to the technical field of preparing alpha hemihydrate gypsum by utilizing desulfurized gypsum. Background technique [0002] Using natural gypsum as raw material, there are two production processes for producing α hemihydrate gypsum: one is the hydrothermal method, that is, after the natural dihydrate gypsum is crushed, a crystal form conversion agent is added to make a slurry with a certain concentration, pressurized and Stir and react for a period of time. After the recrystallization is completed, wash with high-temperature water under normal pressure, dry, and grind to obtain α-hemihydrate gypsum. However, due to the high quality requirements for calcium sulfate dihydrate in the raw material and the high production cost, there is no production line in operation at present. The only remaining hydrothermal production line in China was imported from Germa...

Claims

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Application Information

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IPC IPC(8): C04B11/26
Inventor 潘利祥
Owner BEIJING BUILDING MATERIALS ACADEMY OF SCI RES
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