MICROSCOPIC STUDY OF SPHERES AND MICROSPHERES IN FLY-ASH

Spherical particulates in fly ash from two bituminous coals, two subbituminous coals and one lignite have been studied by interference contrast polarized light microscopy (ICT-PLM) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). Most of the glassy spheres were between 8 and 50 mu m in diameter. Second phase material was seen on many of the solid sphere surfaces. Microspheres attached to the surfaces of larger spheres were found to have different compositions from that of the host sphere. Microparticulate capture by the larger spheres is a phenomenon that needs more study before the capture mechanism and its efficiency can be understood.