SIMULTANEOUS DETERMINATION OF RARE-EARTHS BY X-RAY-FLUORESCENCE SPECTROMETRY USING A FUNDAMENTAL PARAMETERS METHOD

Concentrates extracted from a lateritic mineral deposit were analysed for their rare earth (RE) content by energy-dispersive x-ray fluoresce nce (XRF) spectrometry. The L emission lines of the lanthanides were e xcited with the 22.1 keV Ag K radiation from an annular Cd-109 radiois otope source. The problem of the extensive overlap of the L lines were solved by the AXIL program for deconvolution of XRF spectra. Individu al REs were quantified by preparing semi-transparent pellets of the co ncentrate with starch which served as dilutant and binder. This allowe d correction for sample absorption with the light matrix program of th e QXAS analysis package based on the fundamental parameter method. The method allowed the simultaneous determination of 12 rare earths conta ined in the sample, with a reproducibility of 2.0-29% and accuracy in the range 1.5-24% relative error without the use of standard materials . Detection limits achieved were in the range of 340 ppm for the heavy REs and 4000 ppm for the light REs.