A оne-stage aerodynamic separation of fly ash produced via the pulverized combustion of coal from Kuznetsk basin was carried out. Morphologically homogeneous fractions of microspherical particles, with size parameters – d_max  = 4, 16 и 60 μm and d₉₀ = 10, 40 и 115 μm, were recovered. It was found that all obtained fractions have two major chemical components, namely SiO₂ (54-63 wt %) and Al₂O₃ (21-29 wt %). The phase composition includes amorphous component – aluminosilicate glass (81-84 wt %) and crystalline phases – mullite (7-9 wt %), quartz (4-9 wt %), hematite (about 2 wt %) and ferrospinel (about 1 wt %). An increase in the SiO₂ content and quantity of quartz, as well as a decrease in the Al₂O₃ content and quantity of mullite were observed with increasing fraction size.