Determination of Calcium, Magnesium, Silicon, Iron and Aluminum in Dolomite by Wavelength Dispersive X-ray Fluorescence Spectrometry with Fusion Sample Preparation

A method has been developed for the determination of calcium, magnesium, silica, iron and aluminum in dolomite by Wavelength Dispersive X-ray Fluorescence Spectrometry. Dolomite is a carbonate mineral with a large portion of loss on ignition. In the process of test glass disc preparation, if dry-base sample powder is used, a small amount of test components evaporates with the large amount of carbon dioxide, and causes lower determination results; if the ignited test portion is used, because of moisture and carbon dioxide in air being easily absorbed by the ignited sample powder, the determination results are also be low. To avoid these influences, the mass of the ignited test portion was directly used as the amount of test portion, and fused under 1050℃ with fusion agent lithium tetraborate for glass disc preparation. 5% ammonium iodide solution was used as the releasing agent, and the dilution proportion of test portion and fusion agent was 1:10. Dolomite reference standard materials and samples were used for calibration. The related coefficients of all components were in the range of 0.9940-0.9994, and the limits of detection were in the range of 0.011%-0.48%. Accuracy and repeatability of the proposed method were good, the results of determination were in good agreement with certified values and the relative standard deviation (RSD, n=11) was in the range of 0.5%-1.7%. This method is suitable for simultaneous determination of calcium, magnesium, silica, iron and aluminum in dolomite and its ignited residue.