Determination by x-ray fluorescence spectrometry, of tin and tungsten in ores, concentrates, and residues of scheelite, wolframite and cassiterite

A method of analysis is described for the determination, by X-ray fluorescence spectrometry, of tin and tungsten in non-metallic samples over a concentration range from 15μg g-1 to 75%. For samples containing tin and tungsten in the range 2000 μg g-1 to 75%, the matrix variations are compensated for by the use of pressed-powder briquettes containing an internal standard, coarse river sand, and potassium chloride, the latter two constituents acting as binder, diluent, and grinding aids. For samples containing tin and tungsten in the range 15 to 2000 μg g-1, the potassium chloride is omitted. Zinc and antimony are used as the internal standards for tungsten and tin respectively. Calibration graphs for tin and tungsten are obtained by the use of standard reference materials for cassiterite and scheelite. A wide range of ores, concentrates, and plant process materials are analysed for tungsten and tin by this method. The precision of the method ranges from a relative standard deviation of 0,039 at 50 μg g-1 to 0,005 at 75% for tin, and from a relative standard deviation of 0,015 at 50μg g-1 to 0,008 at 50% for tungsten. The respective lower limits of detection for tungsten and tin by the high-concentration techniques of analysis are 202 and 155μg g-1 and, by the low-concentration technique, the corresponding limits are 6 and 4 μg g-1