Gypsum binder α- and β-modifications from by-product phosphogypsum

The object of research is phosphogypsum obtained in the production of mineral fertilizers at EuroChem - Belorechensk Mineral Fertilizers LLC as a raw material for obtaining construction gypsum. The objective of the study is to obtain construction gypsum - gypsum binder of α- and β-modification with a strength grade of at least G5 in accordance with Russian Standard GOST 125. To achieve this goal, it is necessary to solve the following tasks: to assess the suitability of phosphogypsum as a raw material for obtaining construction gypsum, taking into account the influence of the shelf life in open waste heaps; to establish the main formulation and technological parameters for processing phosphogypsum, allowing to obtain gypsum binder of β-modification of at least G5 grade; to determine the possibility of obtaining gypsum binder of α-modification of at least G5 grade without plasticizers. Methods. The work mainly used standard methods for determining the rheological, physical and physicomechanical properties of the obtained binders in accordance with the methods of Russian Standard GOST 23789. X-ray fluorescence, X-ray phase and thermal analysis methods were used to determine the physicochemical properties of the raw materials. Results. The results of the study showed the invariance of the properties of the obtained binder from the shelf life of phosphogypsum in waste heaps. The suitability of the studied phosphogypsum as a raw material for obtaining gypsum binder of α- and β-modification with a strength grade of at least G5 was proven. In this case, the grade of the α-modification binder reaches the required value without modification with chemical and mineral additives, while the β-modification binder requires such an adjustment to obtain a grade of at least G5.

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