X荧光测定铌钽原矿中铌和钽及不确定度评定

Determination of Niobium and Tantalum in Raw Niobium-Tantalum Ore and Evaluation of Uncertainty by X-ray Fluorescence

本文建立了X射线荧光熔片法测定铌钽原矿中铌和钽的分析方法。采用低稀释比(Li2B4O7:LiNO3:样品=4:0.6:1)制备熔融玻璃片,以光谱纯SiO2、Al2O3和Fe2O3混合物为基体,添加Nb、Ta标准溶液及少量干扰元素Rb、Y、Mo、Zr、W、Ce制备校准曲线所用标准样品。使用Rh靶compton散射线为内标线校正基体效应对Nb元素的影响;Ta元素则外加HfO2,并用Hf Lβ3为内标线。本文讨论了复杂铌钽原矿和本实验试剂中含有的Br、Rb、Y、Mo、Zr、Nb、W、Hf和Ta各元素之间的光谱干扰。对于Br、Rb、Y、Nb及Hf和Ta之间的谱线重叠干扰,采用干扰系数法逐级扣除;而Mo Kα和Zr Kα背景对Nb Kα的影响及W Lα背景对Ta Lα的影响,则分别通过选取40.000°和70.500°公共背景点来避免,最后得到分析元素Nb Kα和Ta Lα谱线净强度。本文选用钽矿石成分分析标准物质(GBW07155)作为方法验证样品,并对Nb、Ta测量结果不确定度进行评定。最终本方法报出结果:w(Nb_(2)O_(5))=(0.044±0.002)%(k=2);w(Ta2O5)=(0.069±0.002)%(k=2)。

An analytical method for the determination of niobium and tantalum in raw niobium-tantalum ore by X-ray fluorescence fusing was established.The fused glass disc was prepared with low dilution ratio(Li2B4O7:LiNO3:sample=4:0.6:1),and the standard sample for calibration curve was prepared with the mixture of spectrally pure SiO2,Al2O3 and Fe2O3 as matrix,and the standard solution of Nb,Ta and a small amount of interfering elements Rb,Y,Mo,Zr,W and Ce were added to prepare the standard sample for calibration curve.The influence of matrix effect on Nb element was corrected by using Rh target compton scattering line as internal marker.Ta element used HfO2 and Hf Lβ3 as the internal marking line.The spectral interference between Br,Rb,Y,Mo,Zr,Nb,W,Hf and Ta elements in complex raw niobium-tantalum ore and the reagent in this experiment is discussed.For the overlapping interference between Br,Rb,Y,Nb and Hf and Ta,the interference coefficient method is used to deduct step by step.The influence of Mo Kαand Zr Kαbackground on Nb Kαand the influence of W Lαbackground on Ta Lαwere avoided by selecting 40.000°and 70.500°common background points,respectively.Finally,the net spectral line intensity of analysis elements Nb Kαand Ta Lαwas obtained.The standard material GBW07155 of raw niobium-tantalum ore was used as the method to verify the sample,and the uncertainty of the measurement results of Nb and Ta was evaluated.Finally,the results of this method are as follows:w(Nb_(2)O_(5))=(0.044±0.002)%(k=2);w(Ta2O5)=(0.069±0.002)%(k=2).