Porous magnesia compositions of a combined structure Olga MiryukRudny Industrial Institute, Republic of Kazakhstan E-mail: psm58@mail.ru Abstract. In this research were developed heat-insulating magnesia compositions with technogenic fillers. A comparative analysis of the structures formed by different methods shows the high porosity of the compositions using a foaming agent, polystyrene pellets. Here was shown the expediency of obtaining porous compositions based on mixed magnesia binders with the addition of wastes of enrichment of skarn-magnetite ores (up to 30 %). The efficiency of the heat-shielding properties of materials is ensured by the creation of a highly porous combined structure by optimizing the formulation of the molding masses and by rational combination of various techniques of porosity. Effect of porosity methods on magnesia compositions structure was investigated. The conditions for formation of combined structures due to combination of cellular, granular and fibrous porosity were determined. Combined structures of various compositions based on technogenic fillers are characterized by porosity of 75 -90%, density of 150 -400 kg/m 3 and coefficient of thermal conductivity of 0.04 -0.08 W/(m 0 C). Methods for preparing molding mixtures have been developed based on the primary contact of the components forming the matrix stability and providing a stable highly porous structure of the compositions.It is revealed that the magnesian compositions are distinguished by increased technology, ensuring the greatest strength of the porous materials.

The results of physicochemical studies of composition and thermal transformations of large-tonnage wastes of skarn-magnetite ore dressing in Kazakhstan are presented. To determine materials’ composition of the following methods were used: X-ray, differential and thermal, Mössbauer and infrared spectroscopy. The stepwise nature of transformation of anthropogenic material during firing, due to polymineral composition of ore dressing wastes is revealed. Provides information on the chemical and mineral composition, thermal transformations of ore dressing wastes. It has been established that the chemical-mineral characteristics of natural silicates determine formation processes and properties of clinker phases. The features of the formation of clinker phases with the participation of the technogenic component of the raw mix, which consist in the activity of low-temperature interactions, the variety of intermediate phases are revealed. It has been established that the staging of belite formation with the participation of actinolite, albite, andradite, grossular, diopside, chlorite, epidote is due to gradual transformations of minerals into intermediate phases C2AS, C3MS2, of which C2S is formed at temperatures of 1000-1300oC. Alite formation is intensified due to high-temperature belite formation and doping impurities. Skarn-magnetite ores wastes are an effective cement raw material, providing high-quality portland cement clinker using low-energy and resource-saving technology.

During research were developed ideas about the formation of C6A4MS phase in the aluminate clinker. The influence of the mineral and chemical composition of the raw mixture on the formation of C6A4MS was studied. Schemes of phase transformations providing synthesis of C6A4MS are proposed in this paper. Within research also have been studied the processes of hydration and hardening of aluminate phases. It was found that C6A4MS exhibits high hydraulic activity. Preference is given for the content of C6A4MS in aluminate clinkers obtained using technogenic materials.

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