熔融制样-X射线荧光光谱法测定硅酸盐和铝土矿中主次组分

采用熔融制样,以土壤、水系沉积物、岩石、铁矿石、铝土矿等标准物质拟合校准曲线,建立了X射线荧光光谱(XRF)同时测定硅酸盐和铝土矿中主次量组分(SiO₂、Al₂O₃、Fe₂O₃、TiO₂、K₂O、Na₂O、CaO、MgO、P₂O₅、MnO)的快速分析方法。确定熔融条件如下:样品与四硼酸锂-偏硼酸锂(质量比为67∶33)混合熔剂在熔融稀释比例为1∶10条件下混合均匀,加入2 mL 500 g/L NH₄NO₃溶液、0.5 mL 300 g/L NH₄Br溶液,于700 ℃预氧化,1 100 ℃温度下熔融。解决了每种矿种都要建立一套分析方法,不能同时测定多种类型地质样品的问题。采用实验方法对GBW07178、GBW07179铝土矿标准物质各组分进行测定,结果的相对标准偏差(RSD,n=12)小于5%,相对误差(RE)小于10%。采用实验方法测定硅酸盐和铝土矿样品,所得结果与湿法值一致。

Simultaneous determination of major and minor components in silicate and bauxite by X-ray fluorescence spectrometry with fusion sample preparation

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 1 100 ℃. 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.