SEMI-LOW-DILUTION FUSION TECHNIQUE FOR ANALYSIS OF GEOLOGICAL, ENVIRONMENTAL AND PRODUCTION PLANT-SAMPLES IN FERROUS AND NONFERROUS INDUSTRIES

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-dispers ive x-ray spectrometry (XRF-WD/ED), the method can be applied generall y in the pretreatment of samples for inductively coupled plasma optica l emission spectrometry (OES-ICP) and atomic absorption spectrometry ( AAS). The choice of flux, constituents such as oxidants and optimizati on of the degree of dilution are discussed. Samples with sulphur conce ntrations of up to 50% can be converted quantitatively into sulphate a nd analysed with an accuracy of the order of 2%. A fundamental model f or the evaluation of measured intensities is used. The model is calibr ated on the basis of standards produced from pure chemicals in the sam e way as the analysed samples. An algorithm is presented which allows loss on fusion, the oxygen content of the non-oxidized components in t he sample and also the ratio of Fe(II) to Fe(III) to be calculated. Ne cessary compromises in model design are based on practical considerati ons and are critically discussed. The method covers concentrations fro m ppm levels up to 100% for most rock-forming components and gives the degree of precision and accuracy required for prospecting and smeltin g operations. (C) 1998 John Wiley & Sons, Ltd.