Analysis of lithium raw materials with WDXRF

Importance of the Topic

Global demand for lithium continues to grow rapidly, driven by widespread adoption of lithium-ion batteries in consumer electronics and electric vehicles. Reliable, accurate analysis of lithium raw materials is essential for quality control at each stage of salt extraction—from brine evaporation to precipitation of lithium carbonate or hydroxide. Wavelength-dispersive X-ray fluorescence (WDXRF) offers a fast, multi-elemental screening method for monitoring critical components such as calcium, sodium, potassium and trace impurities throughout the production chain.

Objectives and Study Overview

This application note demonstrates a dedicated WDXRF calibration tailored to lithium-salt extraction. Key goals include:

• Assessing thermodynamic performance of a factory “Soils and Sediments” calibration refined for lithium-rich matrices.
• Validating quantification limits, detection limits, and precision for major and trace elements in pressed-pellet samples.
• Demonstrating rapid analysis workflows compatible with industrial QA/QC requirements.

Instrumentation Used

The analyses were performed on a Thermo Scientific ARL PERFORM’X WDXRF Spectrometer, equipped with:

• 4,200-W Rh X-ray tube (50 µm Be window)
• Six primary-beam filters, four collimators, up to nine crystals, and two flow-proportional detectors
• Helium purge and LoadSafe design for liquid and powder safety
• Optional small-spot analysis (0.5–1.5 mm) and elemental mapping

Methodology

Sample preparation involved drying lithium-salt raw materials, blending with 10 % Hoechst wax C binder, and pressing 40 mm pellets at 20 ton for 20 s. Calibration employed the standard XR-CAL-SEDI “Soils and Sediments” curve, extended with pressed pellets prepared from KCl, CaCO₃, Li₂CO₃, CaSO₄ and other lithium-salt samples. OXSAS software performed multivariable regression and matrix corrections using theoretical alpha factors. Sample analysis times ranged from 10 to 40 s per element, enabling complete multi-element quantification in under 6 minutes.

Key Results and Discussion

More than 30 elements were quantified with dynamic ranges from ppm to tens of percent. Typical performance metrics included:

• Limits of detection down to sub-ppm for trace metals (e.g., Nb, Mo, U)
• Standard errors of estimate below 0.5 % for major oxides (CaO, Fe₂O₃)
• Linear calibration curves illustrated for Ca, S, Cr with excellent correlation across 0–40 % concentration ranges

High stability of the low-current filament and digital goniometer background correction ensured accuracy for low-level analytes. Optional helium and Secutainer systems enhanced sensitivity and operational safety.

Benefits and Practical Applications

Key advantages of the tailored WDXRF method include:

• Rapid, simultaneous multi-element analysis reducing turnaround times
• Wide concentration range from trace impurities (ppm) to major components (up to 100 %)
• Minimal sample preparation without need for fusion beads
• Robust safety features for handling liquids and powders in production environments

This workflow supports process monitoring during brine evaporation, precipitation steps and product refinement stages.

Future Trends and Potential Applications

Upcoming developments may include:

• Integration of WDXRF into automated inline process control systems for real-time quality feedback
• Enhanced data analytics and machine-learning models to predict process deviations
• Miniaturized, field-deployable WDXRF units for on-site resource screening
• Expanded calibrations covering new lithium-ion battery precursors and recycled battery materials

Conclusion

The ARL PERFORM’X WDXRF Spectrometer, combined with a customized calibration, delivers precise, fast and safe multi-element analysis of lithium raw materials. Its broad dynamic range and streamlined pressed-pellet preparation make it a versatile tool for supporting quality assurance and process optimization across the lithium extraction and refining workflow.