Combustion synthesis of mica-crystalline materials based on fluorphlogopite using mineral raw materials and aluminum production waste

Abstract

The paper considers possible use of aluminum production waste (recycled cryolite Na₃AlF₆) and quartz sand (SiO₂) as the main reagents in the synthesis of mica-crystalline materials based on fluorphlogopite under ambient conditions. The combustion process is shown to depend on the energy additive in the initial mixture and occurs at a rate of 2–5 mm/s in the temperature range of ~700 to 1600°C. The identity of the SHS-fluorphlogopite and pyrogenic fluorphlogopite structures is established. The conditions that allow synthesizing fluorphlogopites with the final product melting in the combustion wave or without it are determined. It appears to be possible to synthesize items by a direct method from dense (2.57 g/cm³) and porous materials based on SHS fluorphlogopites. The possibility of synthesizing materials with the open porosity of up to 35% is demonstrated. A material based on monoclinic sodium fluorphlogopites of NaMg₃AlSi₃O₁₀F₂ and Na₄Mg₆Al₄Si₄O₂₀F₄ compositions is obtained. The results of investigations can be used to develop the SHS technology of item production from mica-crystalline materials.