MORPHOLOGICAL AND CHEMICAL CHARACTERIZATION OF IRON-RICH FLY ASH FRACTIONS.

Fly ash samples collected from the electrostatic precipitator of a coal-fired power plant were separated into relatively magnetic and nonmagnetic fractions. The magnetic portions of these samples were examined by scanning electron microscopy, optical microscopy, and X-ray diffraction. The fly ash particles in the magnetic concentrates were predominantly spherical and were generally solid in cross section, although vesicular particles were common in the larger sizes. The larger particles also exhibited the most diversity with respect to internal morphology. A variety of dendritic growths were among the features observed. X-ray diffraction analyses revealed that the magnetic fly ash fraction was composed primarily of magnetite and lesser amounts of henatite.