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Chen J.,Henan Province Rock and Mineral Testing Center | Chen J.,Key Laboratory of Ministry and Resources Analysis and Exploration of Precious Metals
Yejin Fenxi/Metallurgical Analysis | Year: 2015

The sample was prepared with powder pressed pellet method. The relationship between fluorescence intensity and content of niobium and tantalum in geological samples during the determination by X-ray fluorescence spectrometry (XRF) was discussed. The determination conditions of low content niobium and tantalum were optimized. The detection limit of niobium and tantalum was 1.0 μg/g and 3.1 μg/g, respectively. The precision test was conducted by standard sample of stream sediment (GBW07311). The relative standard deviations (RSD, n=10) of determination results of niobium and tantalum were less than 2.0%. The proposed method was applied to the analysis of geological samples, and the found results were consistent with those obtained by inductively coupled plasma mass spectrometry (ICP-MS). When the content of niobium in geological sample was high, the spectral intensity of niobium decreased at peak value with concavity, which was due to the overflow of counting rate caused by the excessive content of niobium. As a result, the element showed self-absorption phenomenon. This problem was solved in experiments by selecting low tube voltage and tube current (40 kV-40 mA). This condition was applicable for the test of large amount samples. If the conventional tube voltage and tube current (50 kV-60 mA) were used, the method was applicable for the simultaneous determination of multiple elements in few amount of samples using Nb-Kβ(I) as analytical line. For the analysis of high content niobium and tantalum, the found results were consistent with those obtained by gravimetric method. The proposed method could meet the analysis requirements of niobium and tantalum in geological samples with different contents. ©, 2015, Central Iron and Steel Research Institute. All right reserved. Source


Gao Z.-J.,Henan Province Rock and Mineral Testing Center | Gao Z.-J.,Key Laboratory of Ministry and Resources Analysis and Exploration of Precious Metals | Chen J.,Henan Province Rock and Mineral Testing Center | Chen J.,Key Laboratory of Ministry and Resources Analysis and Exploration of Precious Metals | And 4 more authors.
Yejin Fenxi/Metallurgical Analysis | Year: 2015

The certified reference materials of soil, stream sediment, rock, iron ore and bauxite were prepared by fusion method for the fitting of calibration curve. The rapid analysis method for the simultaneous determination of major and minor components (SiO2, Al2O3, Fe2O3, TiO2, K2O, Na2O, CaO, MgO, P2O5 and MnO) in silicate and bauxite by X-ray fluorescence spectrometry(XRF) was established. The fusion conditions of samples were obtained as follows: the sample was uniformly mixed with lithium tetraborate-lithium metaborate (mass ratio of 67:33) with the dilution ratio of 1:10; then, 2 mL of 500 g/L NH4NO3 solution and 0.5 mL of 300 g/L NH4Br solution were added; the sample was pre-oxidized at 700℃ followed by fusion at 1100℃. The proposed method solved the following problems: each ore sample required one set of analysis method; the geological samples with various types could not be determined simultaneously. The components in certified reference material of bauxite (GBW07178 and GBW07179) were determined by proposed method. The relative standard deviation (RSD, n=12) was less than 5%. The relative error (RE) was less than 10%. The proposed method was also applied to the determination of silicate and bauxite samples, and the found results were consistent with those obtained by wet method. ©, 2015, Central Iron and Steel Research Institute. All right reserved. Source

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