熔融制样-波长色散X射线荧光光谱法测定石灰石中主次成分

石灰石属碳酸盐矿物,灼烧减量大。已有系列化学分析方法用于石灰石的分析,但这些化学分析方法操作步骤繁杂,化学试剂用量大,分析周期长。实验建立了波长色散X射线荧光光谱法测定石灰石中CaO、MgO、SiO₂、Fe₂O₃、Al₂O₃含量的方法。以测量灼烧减量后的灼烧基试样作为试料,Li₂B₄O₇为熔剂,50 g/L NH₄I溶液为脱模剂,稀释比为1∶10,于1 050 ℃熔融成试料片,以石灰石标准物质作为标准试料制作校准曲线。各待测组分校准曲线的相关系数在0.993 1~0.999 7之间;精密度考察发现,各组分测定结果的相对标准偏差(RSD,n=11)在0.13%~2.1%之间;标准物质的测定值与认定值的偏差在0~0.39%之间。实验方法最大限度地降低了灼烧基试料吸收空气中水分和CO₂对测定结果的影响。

Determination of major and minor components in limestone by wavelength dispersive X-ray fluorescence spectrometry with fusion sample preparation

As carbonate mineral, limestone has great loss on ignition. A series of chemical analysis methods have been developed for the determination of limestone, but the operation process was complex, and the consumption of chemical reagents was large and the analytical time was long for those methods. A method has been developed for the determination of calcium oxide, magnesium oxide, silica oxide, iron oxide and aluminum oxide in limestone by wavelength dispersive X-ray fluorescence spectrometry. Sample and fusion agent were fused under the temperature of 1 050 ℃ for test portion slice preparation, which the ignited sample was used as test portion, lithium tetraborate was used as fusion agent, and the dilution proportion of test portion and fusion agent was 1∶10, 50 g/L of ammonium iodide was used as releasing agent. The reference standard materials of limestone were used as standard test portion for standard curves preparation, and the correlation coefficients of all components were in the range of 0.993 1-0.999 7. Precision of the proposed method (RSD, n=11) was in the range of 0.13%-2.1%, and the results of determination were in good agreement with certified values and the deviation was in the range of 0-0.39%. The proposed method mostly weakened the influence of the determination results, which moisture and carbon dioxide in air were absorbed by the ignited test portion.