Exploration and Mining of Rare Earth Elements (REE) Using Tube-Based Thermo Scientific Portable XRF Analyzers

Significance of REE Exploration and Mining

Rare earth elements (REEs) are indispensable to a wide range of high-technology and green-energy applications, including electronics, permanent magnets, catalysts and batteries. Despite their relative abundance in the earth’s crust, REEs are rarely found in high-grade, single-mineral deposits, making their exploration and extraction technologically challenging and costly. Portable X-ray fluorescence (XRF) analyzers offer a rapid, on-site tool to qualitatively and quantitatively assess REE concentrations, supporting real-time decision making in the field.

Objectives and Study Overview

This study evaluates the performance of Thermo Scientific portable XRF analyzers (Niton XL3t GOLDD+, Niton XL3t Ultra and Niton XLp 522K) for detecting and quantifying light and heavy REEs in geological samples. A case study using phosphate ore samples from British Columbia, Canada, illustrates how field assays correlate with laboratory reference methods and how calibration adjustments (Cal-Factors) improve analytical accuracy.

Methodology and Operational Workflow

• Sample Preparation: Phosphate samples were pulverized and loaded into cups sealed with polypropylene film.
• Analysis Protocol: Each filter was scanned for 45 seconds over three filters, yielding a total analysis time of approximately three minutes per sample.
• Calibration Strategy: Factory calibrations were supplemented with matrix-matched Cal-Factors derived from project-specific reference materials to refine quantitative results.

Used Instrumentation

• Niton XL3t GOLDD+ and Niton XL3t Ultra: Tube-based analyzers with a 50 kV miniaturized X-ray tube, optimized for light REEs (La–Sm) plus associated elements (Y, Sc, U, Th).
• Niton XLp 522K: Isotope-based analyzer extending detection to heavy REEs (Eu–Dy) alongside the full suite of light REEs.
• Ancillary Tool: RadEye gamma detector recommended for complementary detection of radioactive U and Th in samples.

Key Results and Discussion

Comparative plots demonstrate a strong correlation (R²>0.9) between portable XRF readings (with Cal-Factors applied) and laboratory ICP-MS assays for phosphorus, yttrium, lanthanum and praseodymium. The high fidelity in Y detection suggests the capability to infer heavy REE enrichment indirectly. Type Standardization, a refined calibration procedure, enables direct in-instrument adjustment to align field data with laboratory benchmarks.

Benefits and Practical Applications

• Rapid, on-site REE assays accelerate exploration workflows and reduce the need for time-consuming lab shipments.
• Real-time data supports immediate geological interpretation and drill targeting.
• Cost savings through decreased sample turnaround time and optimized resource allocation.
• Versatility across diverse sample matrices, including carbonatites, bastnäsite, monazite and placer deposits.

Future Trends and Potential Applications

Advancements in portable XRF technology are expected to expand detection limits for trace REEs and enhance calibration methods using machine learning and multivariate corrections. Integration with other field instruments (e.g., gamma spectrometers, handheld LIBS) and drone-borne surveys may further streamline exploration. Continued development of standardization protocols will support more accurate heavy REE quantification and broaden applications in environmental monitoring, process control and circular-economy initiatives.

Conclusion

Thermo Scientific portable XRF analyzers provide a practical, reliable solution for in-field REE exploration, delivering near–laboratory-quality data in minutes. By leveraging tube- and isotope-based platforms along with robust calibration strategies, geoscientists can efficiently evaluate deposit potential, guide sampling campaigns and accelerate project timelines.