Fluorophlogopite by metallothermic SHS from quartz sand and waste product

Abstract

Using quartz sand (SiO₂); Al and Mg powders as reducing agents; a waste product of aluminum production, cryolite Na₃AlF₆, as a source of fluorine; and commercial KClO₄ as a source of oxygen, we made an attempt to synthesize cast fluorophlogopite, NaMg₃Si₃AlO₁₀F₂, by metallothermic SHS in open air. Synthesis conditions have been optimized with respect to preparation of either cast or porous resultant materials. The synthesized materials were found to contain NaMg₃AlSi₃O₁₀F₂, Na₄Mg₆Al₄Si₄O₂₀F₄, MgAl₂O₄, SiO₂, and some amount of unreacted Si. Our results can be regarded as a technological basis for designing a process for SHS production of fluorophlogopites.