Hollow silicate microspheres from fly ashes of the Chelyabinsk brown coals (South Urals, Russia)

Fly ashes from the South Uralian thermal power stations (TPS), using brown coals of the Chelyabinsk basin as combustible, were under study. The phase formation processes, proceeding in an ash fraction of these coals during their combustion, were investigated. The data on chemical composition of fly ashes are presented. Special attention was given to hollow silicate microspheres extracted from the wastes. With the use of a complex of physicochemical methods, morphology and chemical composition of microspheres are described in detail. Globules of all known morphological types made up of silicate glasses of the two discrete compositions, K-Al-Si and Fe-Al-Si, with a predominance of the first type, were found. The phase composition of mineral impurities in the Chelyabinsk coals is recognised optimal for originating hollow silicate microspheres during industrial coal combustion. The microspheres from the South Uralian fly ashes are comparable to microspheres having practical application in size, wall thickness, shape, morphology of a surface, chemical composition and homogeneity. (C) 2000 Elsevier Science B.V. All rights reserved.