Abstract: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.
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