Semi-low-dilution fusion technique for analysis of geological, environmental and production plant samples in ferrous and non-ferrous industries

Abstract

A semi-low dilution fusion method for melting oxides and sulphides, e.g. geological samples, ores and ore processing products, is presented. Although initially intended for use in wavelength- and energy-dispersive x-ray spectrometry (XRF-WD/ED), the method can be applied generally in the pretreatment of samples for inductively coupled plasma optical emission spectrometry (OES-ICP) and atomic absorption spectrometry (AAS). The choice of flux, constituents such as oxidants and optimization of the degree of dilution are discussed. Samples with sulphur concentrations of up to 50% can be converted quantitatively into sulphate and analysed with an accuracy of the order of 2%. A fundamental model for the evaluation of measured intensities is used. The model is calibrated on the basis of standards produced from pure chemicals in the same way as the analysed samples. An algorithm is presented which allows loss on fusion, the oxygen content of the non-oxidized components in the sample and also the ratio of Fe(II) to Fe(III) to be calculated. Necessary compromises in model design are based on practical considerations and are critically discussed. The method covers concentrations from ppm levels up to 100% for most rock-forming components and gives the degree of precision and accuracy required for prospecting and smelting operations. © 1998 John Wiley & Sons, Ltd.