The rapid determination by x-ray-fluorescence spectrometry of tungsten in tungsten ores and concentrates

A method is presented that is applicable to tungsten concentrations above 0,1 per cent. Matrix variations are suppressed by a tenfold to fiftyfold dilution of the sample material during fusion, which eliminates any mineralogical effects and produces a clear glass disc that is used direct for intensity measurements. Residual matrix variations are compensated for by application of the background-ratio technique, and the intensity measurements are evaluated by comparison with synthetic standards, the calculation being done on-line by use of an Olivetti Programma 602 desk-top computer. An annotated computer programme is provided for calculation of the curve of the calibration graph and evaluation of the sample intensities. The method is rapid and has a coefficient of variation of 1,5 per cent at a level of 50 per cent tungsten when used under routine conditions. Comparison with the results of a wet-chemical method showed the proposed method to have no bias