A new sample preparation method for WD-XRF analysis of sulfide ores by fusion techniques: a BN crucible for protection against contamination and quantitative retention of sulfur

Abstract

In this article, a methodology is described for the wavelength-dispersive X-ray fluorescence analysis of sulfide ores by fusion techniques. A boron nitride crucible is successfully utilised during pre-oxidation with no adhesion of sample powder and contamination. The combination of oxidant LiNO₃ and flux Li₂B₄O₇ at a mass ratio of 20 : 80 is demonstrated to be suitable for the quantitative retention of sulfur and the formation of homogeneous sample beads. The optical oxidation parameters, obtained by an orthogonal experiment L₉(3⁴) using the results obtained from the sulfur retention ratio using the sulfur analyser, for the quantitative retention of sulfur are as follows: temperature, 650 °C; time, 30 min and dilution ratio, 1 : 30. Fusion at 1000 °C indicates that sulfur does not volatilise as Li₂SO₄. The quantitative retention of sulfur in the entire process is validated by independent methods, such as X-ray diffraction, thermogravimetry-differential thermal analysis, as well as by the use of a sulfur analyser and analysis of reference materials. Moreover, 13 major elements present in sulfide ores were simultaneously and rapidly measured with precision and safety.