Determination of 13 Major and Minor Elements Including Nb, Sr, Ba, Si, Al, and Fe in Niobium Concentrates by Wavelength Dispersive X-ray Fluorescence Spectrometry with Fused Bead Sample Preparation

For the determination of 13 major and minor elements (including Nb, Sr, Ba, etc.) in niobium concentrate, conventional techniques such as inductively coupled plasma-optical emission spectrometry/mass spectrometry (ICP-OES/MS), spectrophotometry, gravimetry, colorimetry, and atomic absorption spectrometry are widely adopted. These methods generally suffer from cumbersome sample pretreatment and the inability to determine multiple major and minor elements simultaneously. The analysis of rock-forming elements (e.g., Si, Al, Fe, Ca, Mg, K, Na, Ti, P, Mn) in rocks and minerals also requires considerable operational experience. For Nb determination, both acid dissolution and alkali fusion are susceptible to interference from coexisting elements, which can compromise accuracy. X-ray fluorescence spectrometry (XRF) boasts the advantage of rapid batch analysis and has been extensively applied in the detection of various ores. In this work, samples were fused with a mixed flux of lithium tetraborate–lithium metaborate (mass ratio 67:33). This process ensures the uniform distribution of target elements as stable oxides within glass pellets, thereby effectively eliminating matrix, mineral, and particle effects. Calibration curves were constructed using standard reference materials (SRMs) for tantalum ore, niobium concentrate, and rock composition analysis, as well as using artificially synthesized SRMs. Matrix effect correction was performed using Rh Kα Compton scattering intensity as the internal standard for niobium and strontium, while the empirical coefficient method was employed for the other elements. Experimental parameters including flux selection, dilution ratio, pre-oxidation, fusion temperature, and holding time were optimized to address spectral interference issues (e.g., Br on Al, Sn on Si, and Y and Th on Nb).Validation via artificially synthesized niobium ore standard reference materials and method comparison demonstrated that the limits of detection (LODs) for all elements were ≤0.011%, the relative standard deviations (RSDs) were ≤3.05% (n=6), and the relative errors (RE) were ≤7.14% (n=6). These performance metrics comply with the requirements specified in the standard DZ/T 0130.3-2006. The proposed method features simple pretreatment and high analytical efficiency, enabling the simultaneous determination of 13 major and minor elements with a single technique and overcoming numerous drawbacks of conventional methods.