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A method for preparing α-hemihydrate gypsum with alcohol aqueous solution as crystallization medium

A technology of hemihydrate gypsum and alcohol aqueous solution, which is applied in the field of preparing α-hemihydrate gypsum by the normal pressure solution method, and achieves the effects of easy reuse, simple operation and low energy consumption

Inactive Publication Date: 2011-12-28
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, some methods of producing α-hemihydrate gypsum from dihydrate gypsum with strong acid as the crystallization medium have been proposed, but they are still based on the electrolyte solution as the crystallization medium

Method used

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  • A method for preparing α-hemihydrate gypsum with alcohol aqueous solution as crystallization medium
  • A method for preparing α-hemihydrate gypsum with alcohol aqueous solution as crystallization medium
  • A method for preparing α-hemihydrate gypsum with alcohol aqueous solution as crystallization medium

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Embodiment 1

[0035] according to figure 2 In the process flow shown, an ethanol aqueous solution with a mass concentration of 60% is prepared, and dihydrate gypsum is added and mixed to form a slurry with a solid mass concentration of 3%. Transport the slurry to the crystallization reactor, maintain the temperature of the slurry in the reactor at 80°C, and control the residence time of the slurry for 6.5 hours. After the conversion is completed, extract the slurry and send it to a vacuum belt filter for solid-liquid separation. The separated solid phase is washed with hot water at 50°C, and then sent to an oven to dry at 40°C, and it is α-hemihydrate gypsum after collection. The separated liquid phase is directly reused or combined with washing water for distillation to recover ethanol.

Embodiment 2

[0037] according to figure 2 As shown in the process flow, prepare ethanol-isopropanol-water solution with a mass concentration of 44%, wherein the mass ratio of ethanol to isopropanol is 1.0, add dihydrate gypsum and mix to form a slurry with a solid mass concentration of 36%. Transport the slurry to the crystallization reactor, maintain the temperature of the slurry in the reactor at 90°C, and control the residence time of the slurry for 4.3 hours. After the conversion is completed, extract the slurry and send it to a vacuum belt filter for solid-liquid separation. The separated solid phase was washed with hot water at 54°C, then sent to an oven for drying at 77°C, and the collected solid phase was α-hemihydrate gypsum. The separated liquid phase is directly reused or combined with washing water for distillation to recover ethanol and isopropanol.

Embodiment 3

[0039] according to figure 2 In the process flow shown, an aqueous solution of n-propanol with a mass concentration of 50% is prepared, and dihydrate gypsum is added and mixed to form a slurry with a solid mass concentration of 18%. Transport the slurry to the crystallization reactor, maintain the temperature of the slurry in the reactor at 82°C, and control the residence time of the slurry for 17.2 hours. After the conversion is completed, extract the slurry and send it to a plate and frame filter press for solid-liquid separation. The separated solid phase is washed with hot water at 70°C, and then sent to an airflow dryer to dry at 96°C. After collection, it is α-hemihydrate gypsum. The separated liquid phase is directly reused or combined with washing water for distillation to recover n-propanol.

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Abstract

The present invention discloses a method for preparing alpha-semihydrated gypsum by using an aqueous solution of an alcohol as a crystallization media. The method comprises the following steps: (1) adding gypsum to an aqueous solution of an alcohol, then uniformly mixing to form gypsum suspension slurry; (2) heating the gypsum suspension slurry, carrying out a normal pressure hydrothermal phase inversion reaction to obtain alpha-semihydrated gypsum suspension slurry; (3) carrying out solid-liquid separation for the alpha-semihydrated gypsum suspension slurry, washing the separated solid phasethrough hot water and drying to obtain the alpha-semihydrated gypsum product. With the present invention, the method provided by the present invention has advantages of the normal pressure salt solution method for preparing the alpha-semihydrated gypsum; with the method, the disadvantages of high impurity content, corrosion of the production system, and the like are overcome; the production conditions are mild.

Description

technical field [0001] The invention relates to a preparation process of α-hemihydrate gypsum, in particular to a method for preparing α-hemihydrate gypsum by using dihydrate gypsum as a raw material through a normal-pressure solution method. Background technique [0002] α-hemihydrate gypsum is a type of gypsum with excellent performance. Its products have the characteristics of high hardness, high strength, and good wear resistance. medicine and other fields. But the gypsum produced naturally is dihydrate gypsum and anhydrous gypsum, and α-hemihydrate gypsum is obtained by dehydration of dihydrate gypsum. [0003] The α-hemihydrate gypsum preparation technology that has been popularized and applied can be roughly divided into two categories: gas phase autoclaving method and liquid phase autoclaving method. The general operation process of these two types of processes is as follows: place the crushed, screened or pressed dihydrate gypsum raw material in a closed high-pres...

Claims

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Application Information

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IPC IPC(8): C04B11/02
Inventor 官宝红蒋光明
Owner ZHEJIANG UNIV