Direct determination of zinc, lead, iron and total sulphur in zinc ore concentrates by X-ray fluorescence spectrometry

Abstract

A direct X-ray fluorescence (XRF) method has been developed for the rapid determination of zinc, lead, iron and total sulphur present in zinc ore concentrates. The concentrations of the elements present, mainly as sphalerite, galena, pyrite and pyrrhotite, vary widely: Zn, 40–65; Pb, 0.1–10; Fe, 0.5–11; and S, 25–33%m/m. Using a wavelength-dispersive X-ray spectrometer and samples prepared as briquettes, Zn and Pb may be determined directly using the Kβ and Lγ1 lines, respectively. For Zn, a mathematical model (concentration-based correction equation) was applied to correct for inter-element effects. For the determination of Fe the ratio of the fluorescence intensities of the Fe Kα and Zn Kβ lines was used and, for the determination of total S, the intensity of the S Kα line was corrected with the Rayleigh scatter tube line, Rh Lα. For both iron and total sulphur, subsequent application of the mathematical model helped to correct for the residual inter-element effects. Good agreement was obtained between experimental and certified values for two international reference materials.