Composition characterization of lithium-rich minerals as an exploitable source of lithium using ICP-OES

Importance of the topic

Reliable quantification of lithium and associated elements in mineral ores is critical for assessing the viability of mining sources for electric vehicle batteries and other applications. ICP-OES offers the multi-element capability and dynamic range needed to characterize complex lithium-rich minerals and support sustainable resource development.

Objectives and study overview

This study evaluates the Thermo Scientific iCAP PRO X ICP-OES Duo for simultaneous analysis of twelve elements in zinnwaldite samples. It aims to optimize digestion procedures, demonstrate method accuracy using certified reference material, and assess performance on real mining samples.

Methodology and instrumentation

The analytical workflow employs closed-vessel microwave digestion with three acid mixtures (HF/HNO3/HCl, aqua regia, H3PO4) to target different element groups. Samples and a NIST soil CRM (2709a) were digested and diluted to 0.2% total dissolved solids. Instrumental analysis was carried out on an iCAP PRO X Duo system equipped with a ceramic D-torch, PTFE spray chamber, Burgener MiraMist nebulizer, and alumina injector. Axial and radial plasma views were selected per element using Qtegra ISDS software. A yttrium internal standard compensated for drift, and calibration employed multi-element standards with continuing calibration verification.

Main results and discussion

Recovery studies on CRM showed 91–105% accuracy across all elements. HF digestion was essential for Ti, aqua regia for Fe, and phosphoric acid for Al, illustrating the need for multiple digestion protocols. Instrumental limits of detection ranged from 0.0001 to 0.091 mg·L⁻¹ with R² >0.9994. Analysis of four zinnwaldite samples revealed Li concentrations between 936 and 9657 mg·kg⁻¹ and variable levels of major cations and trace metals. A 6-hour sequence of 110 samples yielded CCV RSDs ≤1.9% and internal standard recoveries of 89–103%, confirming robust long-term stability.

Benefits and practical applications

• Concurrent quantification of major and trace elements in a single run reduces turnaround and sample preparation.
• High accuracy and low detection limits support decision-making for ore viability and quality control.
• Robust performance under varied acid matrices facilitates batch processing of diverse mineral samples.

Future trends and potential applications

Advancements may include integration with laser-based sampling for direct solid analysis, automated on-line monitoring of mining streams, expansion to other critical battery metals, and coupling with speciation techniques to assess environmental impact. Software enhancements will further streamline method development and data processing.

Conclusion

The optimized ICP-OES method on the iCAP PRO X Duo provides accurate, sensitive, and robust multi-element analysis of lithium-rich minerals. It enables reliable resource characterization, supports environmental considerations, and accelerates mineral screening for battery production.

References

• Thermo Scientific Application Note 000602: Determination of lithium and other elements in brine solutions using ICP-OES.
• Ressortforschungsplan of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.
• British Geological Survey: Lithium, June 2016.
• Mueller S., Scott P.W., Evans M.J. Kaolinisation, mineralisation and structures in biotite granite at Bodelva, St. Austell, Cornwall. Geoscience in South-West England, 1999, 9, 310–317.