Method for preparing anhydrous gypsum through phosphogypsum crystal transformation and purification

By using dialkali metal salts of ethylenediaminetetraacetic acid and alkali metal chlorides as crystal-transforming agents, the crystal growth of phosphogypsum was regulated, solving the problems of high energy consumption and unfavorable whisker structure in the preparation of anhydrous phosphogypsum. High-purity, high-compressive-strength columnar anhydrous gypsum was prepared, broadening its application range.

CN120829261APending Publication Date: 2025-10-24WUHAN INST OF TECH
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Patent Information

Application Number
CN202511085380.8
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-08-04
Publication Date
2025-10-24

AI Technical Summary

Technical Problem

Existing methods for preparing anhydrous gypsum from phosphogypsum suffer from high energy consumption, crystal structure collapse, and whisker structures that are not conducive to high-strength applications, especially limiting their application in the construction field.

Method used

The crystal growth process of phosphogypsum was controlled by using dialkali metal salts of ethylenediaminetetraacetic acid and alkali metal chlorides as crystallization agents. High-purity, high-compressive-strength columnar anhydrous gypsum was prepared by reacting it with a mixed solution of sulfuric acid and nitric acid under specific temperature and time conditions.

Benefits of technology

This method enables the efficient and low-energy preparation of high-purity, high-compressive-strength columnar anhydrous gypsum, broadening its application areas, especially its potential in building materials.

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Abstract

The invention provides a method for preparing anhydrous gypsum through phosphogypsum crystal transformation and purification, and relates to the technical field of industrial solid waste recycling. The method comprises the following steps: uniformly mixing the phosphogypsum, the acidic mixed solution and the crystal modifier, reacting under specific conditions, and filtering while hot after the reaction is finished, thereby obtaining the anhydrous gypsum. According to the technical scheme, the growth process of the anhydrous gypsum is regulated and controlled by introducing the specific crystal modifier, so that the anhydrous gypsum with high purity and high compressive strength is obtained. The method is suitable for preparing the anhydrite by taking the industrial byproduct phosphogypsum with high phosphorus impurity content as the raw material, the produced anhydrite is good in crystallization conversion, excellent in product quality, simple in process, high in efficiency and low in energy consumption, the water demand is lower than that of a traditional method, the phosphogypsum waste can be utilized, and resource circulation is realized.
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