Crush and Acid Resistance of Microsphere Narrow Fractions from Fly Ash as the Basis of Composite Materials

Abstract

The crush test and acid resistance of microsphere narrow fractions with average diameter dav of 5, 8 and 25 μm of the SiO2–Al2O3–FeO system and with dav of 4 and 10 μm the CaO–SiO2–Al2O3– FeO system separated from fly ash from pulverized combustion of Ekibastuz and Irsha-Borodinsky coals were studied. It has been established that all investigated ash fractions of both raw materials are characterized by high strength: microspheres of a larger narrow fraction with dav = 25 μ m a re not destroyed by compressive loading at pressures up to 51.7 MPa, dispersed narrow fractions of microspheres with dav ≤ 10 μm – up to 68.9 MPa. Microsphere narrow fractions with aluminosilicate composition have satisfactory acid resistance; the weight loss after treatment with 15 % hydrochloric acid at 65 °C for 30 minutes was 10–15 wt. %