Determination of mineralogical composition of spent fluorescent powders by coupling ICP-spectroscopy and electronic microprobe analyses

The aim of the work is to determine the concentration (mineralogical composition) of the solid phases contained in the fluorescent powders removed from spent fluorescent lamps. The calculation is based on the results of chemical analysis, carried out with inductively coupled plasma spectroscopy (ICP) on the fluorescent powders as a whole. This analysis was coupled with the results of crystallochemical analysis carried out with electron microprobe (EMA) on each solid phase to determine its chemical composition. The coupling between chemical and crystallochemical results was accomplished through a matrix method supported by principal component analysis (PCA). The confidence intervals, around the estimated concentration values, that contain the true concentration values, were also calculated for each phase at a chosen confidence level. The method also permits determination of the mineralogical composition of the products obtained from separation treatments carried out on the powders to recover each phase at the highest grade.