With the very large information depth available in micro-beam XRF, it is possible to generate two-dimensional maps of the elemental distribution over large spherical fly-ash particles with a resolution down to about 1 μm. These particles possess a large degree of spherical symmetry owing to the process of their formation. By applying special reconstruction algorithms, the symmetric part of the elemental distribution can be reconstructed from the two-dimensional projection maps and subtracted from the original map. The results show that such a fly-ash particle can be split into a radial symmetric part containing non-volatile carbonaceous compounds and an asymmetric part representing precipitates or sub-particles formed within the fly-ash particle. The symmetric part shows a distinctly visible outer and an inner shell. By using the asymmetric part of the distribution, the interior of the fly-ash particle can be studied without interference from the inner and outer shells.
ASJC Scopus subject areas