Analyzing ore concentrates and grade control with handheld XRF

Significance of the Topic

Handheld X-ray fluorescence (XRF) plays a critical role in the mining industry by providing rapid, on-site elemental analysis of ore samples across different stages of exploration and production. Grade control and concentrate analysis are essential to ensure economic viability and process efficiency, especially when dealing with low metal concentrations in raw ore and higher concentrations in processed concentrates.

Objectives and Study Overview

This study aims to demonstrate the application of an empirical calibration approach (UserMethod) on a Thermo Scientific Niton XL3t GOLDD handheld XRF analyzer for accurate quantification of molybdenum, copper, and iron in high-grade molybdenite concentrate samples. Key objectives include:

• Generating calibration curves linking XRF intensity to known lab assay concentrations.
• Evaluating accuracy and potential biases across a range of metal concentrations.

Methodology and Instrumentation

The empirical calibration (UserMethod) involves analyzing molybdenite concentrations ranging from 25% to 65% Mo by weight and recording XRF intensity values (counts per second per microampere). Calibration curves are derived from plots of intensity against laboratory reference concentrations, yielding linear trendline equations used to convert intensity readings of unknown samples into metal concentrations.

Instrumentation

• Thermo Scientific Niton XL3t GOLDD handheld XRF analyzer.

Main Results and Discussion

Calibration for molybdenum, copper, and iron exhibited strong linear correlations with lab assays: R² values of 0.97 (Mo), 0.99 (Cu), and 0.97 (Fe). Trendline slopes ranged between 0.95 and 1.05, indicating minimal systematic bias. These results confirm the reliability of the UserMethod for high-concentration ore samples, ensuring that handheld XRF readings reflect true elemental content.

Benefits and Practical Applications

• Rapid, on-site quantification of high-grade concentrates with minimal sample preparation.
• Real-time grade control to optimize processing and reduce waste.
• Flexibility to apply the same method across different metals and concentration ranges.

Future Trends and Opportunities

As handheld XRF technology advances, future developments may include:

• Enhanced detector sensitivity for lower detection limits.
• Improved calibration algorithms using machine learning.
• Integration with automated sampling systems and digital mine management platforms.
• Expansion into critical elements and environmental monitoring applications.

Conclusion

The empirical UserMethod on a Niton XL3t GOLDD analyzer provides accurate and efficient analysis of molybdenite concentrates, matching laboratory results with minimal bias. This approach supports effective grade control in mining operations and demonstrates the broader potential of handheld XRF for on-site quantitative analysis of ore concentrates.

References

• Thermo Fisher Scientific. Application Note MCS-AN1065-EN, May 2024.