Quantitative analysis of CeO 2 -associated mineral composites based on terahertz time-domain spectroscopy technology

Abstract

The complex and highly variable mineralogical assemblages in rare earth deposits pose a significant challenge for accurate compositional analysis. Conventional techniques such as scanning electron microscopy and optical microscopy often lack the precision required for quantitative concentration measurements of constituent minerals. This study employs terahertz time-domain spectroscopy (THz-TDS) to achieve non-destructive, high-precision quantification of mineral concentrations in rare earth systems. The experiments are performed using a THz-TDS system driven by a Ti:sapphire femtosecond laser. Measurements are carried out under a dry atmosphere on mixtures of calcium carbonate (CaCO 3 )–cerium oxide (CeO 2 ) and barium sulfate (BaSO 4 )−CeO 2 . Based on the terahertz wave attenuation characteristics during propagation through a material, a highly linear relationship (R 2 >0.99) is established between the transmitted signal amplitude and the concentration of associated minerals. This differential response originates from the distinct terahertz absorption characteristics of CeO 2 relative to the associated minerals, enabling rapid and accurate concentration determination. Comparative analysis with X-ray diffraction (XRD) Rietveld refinement demonstrates the superior performance of THz-TDS (R 2 =0.97 for CaCO 3 , 0.98 for BaSO 4 ), whereas XRD results exhibit lower correlation (R 2 =0.90 for CaCO 3 , 0.97 for BaSO 4 ), attributable to inherent limitations such as preferred orientation effects and microstructure-dependent intensity variations. This study establishes a robust, non-destructive analytical method for quantifying mineral compositions in heterogeneous rare earth ores, with significant implications for ore genesis studies, mineral processing optimization, and efficient resource utilization.