FRACTIONATION AND CHARACTERIZATION OF TEXAS LIGNITE CLASS-F FLY-ASH BY XRD, TGA, FTIR AND SFM

Fly ash is a complicated heterogeneous material and utilization of it requires a detailed knowledge of the physical and chemical characteris tics. In the present study Texas lignite class 'F' fly ash was examine d by X-ray diffractometer (XRD), thermogravimetric analyzer (TGA), Fou rier transformed infrared spectrophotometer (FTIR) and scanning force microscopy (SFM). The XRD and FTIR data indicated that the bulk fly as h was composed of mullite, quartz, cristobalite and amorphous aluminos ilicates. The TGA indicated a negligible amount of adsorbed water, and an absence of structural water in the amorphous aluminosilicate phase s. The magnetic component of the fly ash was made up of magnetite and present mostly in the coarser fractions greater-than-or-equal-to 50 mu m. The SFM of the bulk fly ash showed the presence of amorphous glassy surface and quartz. The fractionated samples indicated that about 90 wt% of the fly ash was composed of greater-than-or-equal-to 50 mum par ticles. The amorphous component increased with the decreasing particle fractions. Hence, the chemical reactivity of fly ash will increase wi th the decreasing particle size.