Monte Carlo simulation of secondary fluorescence in small particles and atphase boundaries

Results from Monte Carlo simulations and experimental measurements of X-ray spectra of small Cu-particles in Fe-containing slags are presented. The an alyzed Cu-particles remain suspended in flash smelting and Cu convert I sla gs, which contain Fe up to about 33 wt%, and have diameters ranging from 5 up to 100 mu m Conventional standardless analysis of measured X-ray spectra gives an apparent Fe content of similar to 1-5 wt%, depending on the parti cle diameter; which cannot be explained in terms of the thermodynamic solub ility of Fe in solid Cu. In order to study the influence of the Fe-containi ng slag to the apparent Fe content in the particles, X-ray spectra have bee n computed by means of Monte Carlo simulation of the coupled electron and p hoton transport. The simulation code used is largely based on the general-p urpose simulation package PENELOPE and it incorporates ionization cross sec tions evaluated fi um an optical-data model and bremsstrahlung cross sectio ns that reproduce radiative stopping power derived from partial wave calcul ations. Simulated Fe k-ratios, for different experimental situations, have been found to be in satisfactory agreement with measurements. The apparent Fe content is explained in terms of secondary fluorescence of Fe K alpha by Cu K alpha X-rays.