Analysis of Lithium Ores Using Handheld Direct Diffuse Reflectance FTIR Spectroscopy

Significance of the Topic

Rapid, on-site analysis of lithium-bearing ores is essential to meet the growing demand for lithium in rechargeable batteries and energy storage systems. Traditional laboratory methods require extensive sample preparation and cryogenic cooling, leading to delays and increased costs. A handheld FTIR approach enables immediate, non-destructive mineral identification in the field, optimizing exploration and processing workflows.

Objectives and Study Overview

This application note presents a direct diffuse reflectance FTIR (direct-DRIFTS) method using the Agilent 4300 handheld FTIR spectrometer. The goals were to eliminate sample grinding and liquid nitrogen cooling, acquire full mid-infrared spectra in under a minute, identify lithium ores with high selectivity, and develop quantitative models for mineral content.

Methodology and Used Instrumentation

The Agilent 4300 handheld FTIR was fitted with a custom diffuse reflectance interface for direct-DRIFTS measurements. Spectra were collected over 650–5000 cm–1 at 4 cm–1 resolution using 128 background and sample scans. Data acquisition and library matching were managed via Agilent MicroLab Mobile software, while Agilent MicroLab Expert on PC facilitated chemometric model development. Reference libraries included 165 industrial ore spectra and 971 geological standards.

Main Results and Discussion

• Comparison with ATR Spectroscopy

• Direct DRIFTS yielded richer spectral details, stronger Reststrahlen features, and extended signals into the near-infrared compared to diamond ATR on ground samples.

• Identification of Lithium Ores

• Spectra for spodumene, petalite, amblygonite, zinnwaldite, and lepidolite exhibited distinctive mid-IR signatures correlating to their Li2O content.

• Accessory Mineral Detection

• Common host-rock minerals (quartz, feldspars, biotite, garnet, tourmaline, apatite) were identified by library matching, aiding in targeting Li-enriched zones.

• Quantitative Chemometric Models

• Partial least squares models predicted drill core depth and calcite percentage (a vector mineral) with R2>0.97.
• Spodumene (SC6 concentrate, 6–7 % Li2O) and petalite (3.5–4.9 % Li2O) content were quantified directly from spectra with high confidence.

Benefits and Practical Applications

The direct-DRIFTS handheld method offers:
• Immediate, non-destructive field measurements
• No sample grinding or liquid nitrogen
• Sub-minute spectral acquisition and identification
• On-board library matching and multivariate predictions
These features streamline mineral exploration, grade control, and resource evaluation in remote locations.

Future Trends and Applications

Advancements may include:

• Custom spectral libraries for emerging deposit types
• Integration of real-time AI for automated feature recognition
• Wireless data transfer and cloud-based analytics
• Coupling with geophysical sensors for comprehensive surveys
• Applications in battery recycling and process monitoring

Conclusion

The Agilent 4300 direct-DRIFTS method delivers rapid, robust, and accurate analysis of lithium ores without sample preparation. Portable, high-resolution FTIR measurements enable reliable mineral identification and quantitative estimates of ore quality, supporting efficient exploration and processing of critical lithium resources.

References

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