Determination of 13 Major and Minor Elements includings Nb, Sr, Ba, Si, Al, Fe in Niobium Concentrates by Wavelength Dispersive X-ray Fluorescence Spectrometry Using 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 are generally plagued by cumbersome sample pretreatment procedures and the inherent limitation of being unable to simultaneously determine multiple major and minor elements. The analysis of rock-forming elements (e.g., Si, Al, Fe, Ca, Mg, K, Na, Ti, P, Mn) in rocks and minerals demands a certain level of operational experience. For Nb determination, both acid dissolution and alkali fusion approaches are susceptible to interference from coexisting elements, resulting in compromised result 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), which ensured the uniform distribution of target elements in the form of stable oxides within glass pellets, thereby effectively eliminating matrix effects, mineral effects, and particle effects. Calibration curves were constructed using standard reference materials (SRMs) for tantalum ore, niobium concentrate, and rock composition analysis, as well as artificially synthesized standard reference materials. 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, Y and Th on Nb).Validation via artificially synthesized niobium ore standard reference materials and method comparison demonstrated that the limit of detection (LOD) for each element was ≤0.011%, the relative standard deviation (RSD) was ≤3.05% (n=6), and the relative error (RE) was ≤7.14% (n=6). These performance metrics comply with the requirements specified in the standard DZ/T 0130.3—2006 (Quality Management Specification for Testing in Geological and Mineral Laboratories). This proposed method offers 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.