波长色散X射线荧光光谱法测定钽铁和铌铁矿中钽铌铀钍

钽铁和铌铁矿中钽和铌含量直接关系到矿物资源的品位,铀和钍由于具有放射性,其含量也受到重点关注,但现有检测方法过程复杂,耗时较长。采用四硼酸锂和偏硼酸锂等质量比组成的混合熔剂,选择1∶20超低稀释比,以硝酸钡为氧化剂,采用高纯氧化物熔融制备人工参考样品,以铪和钼元素分别作为钽和铌的内标元素,铀和钍测定时不用内标,建立了波长色散X射线荧光光谱法(WDXRF)测定钽铁和铌铁矿中钽、铌、铀和钍含量的分析方法。结果表明,钽、铌、铀和钍各元素氧化物的检出限分别达到0.016%、0.006%、0.003%和0.004%,对应氧化物参考样品校准曲线线性范围较宽,相关系数分别达到0.999 9、0.999 9、0.999 1、0.999 3。选用实验方法测定钽铁和铌铁矿样品进行精密度试验,各元素对应氧化物测定结果的相对标准偏差(RSD,n=10)如下:五氧化二钽为0.062%~0.38%,五氧化二铌为0.046%~0.18%,八氧化三铀为0.26%~0.52%,二氧化铪为0.27%~1.1%。分别采用实验方法和电感耦合等离子体原子发射光谱法对钽铁和铌铁矿样品进行测定以进行方法比对,结果表明,两种方法测定结果基本一致。

Determination of tantalum,niobium, uranium and thorium in tantalite and niobite by wavelength dispersive X-ray fluorescence spectrometry

The grade of mineral resources is directly linked to the contents of tantalum and niobium in tantalite and niobite. Since uranium and thorium have radioactivity, their contents has attracted much attention. However, the current detection methods is complex and time-consuming.The mixed flux was prepared with lithium tetraborate and lithium metaborate in equal mass ratio. The artificial reference samples were prepared by high purity oxide fusion with ultra-low dilution ratio of 1∶20 and barium nitrate as oxidant. Hafnium and molybdenum were selected as the internal standard elements of tantalum and niobium, respectively. For the determination of uranium and thorium, the internal standards were not used. Thus, an analytical method of tantalum, niobium, uranium, and thorium in tantalite and niobite by wavelength dispersive X-ray fluorescence spectrometry was established. The results showed that the limit of detection for oxides of tantalum, niobium, uranium, and thorium was 0.016%, 0.006%, 0.003% and 0.004%, respectively. The linear ranges of calibration curves corresponding to the oxides reference samples were wide. The correlation coefficient was up to 0.999 9, 0.999 9, 0.999 1 and 0.999 3, respectively. The precision tests were conducted for determination of tantalite and niobite samples by proposed method. The relative standard deviation(RSD,n=10) for the determination results of each element oxides were as follows:tantalum pentoxide of 0.062%-0.38%, niobium pentoxide of 0.046%-0.18%, triuranium octoxide of 0.26%-0.52%, hafnium oxide of 0.27%-1.1%. The proposed method and inductively coupled plasma atomic emission spectrometry was applied in determination of tantalite and niobite samples for methods comparison, the results were consistent.