Use of Sample Preparation Tools in Mining and Mineral Exploration Projects

Importance of the topic

Reliable sample preparation and portable XRF analysis are essential to overcome heterogeneity in geological materials and to provide timely geochemical data for exploration decisions.

Objectives and overview of study

This study aims to compare assay results from unprepared and prepared rock core samples using portable XRF against laboratory analyses, and to demonstrate identification of Cu Mo anomalous zones at depth. The main goals are

• Comparison of assay results from direct sample scanning and powder samples
• Correlation of portable XRF data with lab based ICP AAS analyses
• Mapping of copper molybdenum anomalies using field portable XRF

Methodology and instrumentation

Field tests were conducted on one meter core intervals from a Cu Mo porphyry deposit in northwest Canada. Three analytical protocols were applied using a Thermo Scientific Niton XL3t GOLDD+ portable XRF analyzer in mining mode:

• Direct scanning of unprepared core along one meter length for 80 seconds
• Analysis of powder obtained by electric hammer mill, measured in cups for 240 seconds
• Analysis of powder produced by angle grinder sampler, measured in cups for 240 seconds

Sample preparation tools include a portable mill and angle grinder kit to produce homogeneous powders. Cups were fitted with polypropylene film to ensure consistent measurements.

Main results and discussion

All three portable XRF approaches correlate strongly with laboratory results, yielding R2 values above 0.9 for copper and molybdenum when using prepared powders. For unprepared direct shots, correlation for copper improved from 0.81 to 0.84 and 0.86 when using mill and grinder powders respectively. Molybdenum correlation increased from 0.87 in direct shots to 0.95 with grinder powder. Depth profiles of Cu and Mo show that prepared sample assays more accurately reflect the size and shape of anomalous zones while direct scans can rapidly identify anomalies in the field.

Benefits and practical applications

Key advantages of incorporating sample preparation tools into field portable XRF workflows include

• Enhanced repeatability and correlation with laboratory data
• Rapid identification of geochemical anomalies during early and mid stage exploration
• Reduction in number of samples requiring laboratory analysis
• Immediate on site decision support for drill targeting
• Non destructive analysis allowing residual material for further tests

Future trends and applications

Ongoing developments may focus on automated sample prep devices integrated with portable XRF, real time data integration in exploration software, extension to additional deposit types and elements, and adaptation of drone or robotic platforms for remote field assays.

Conclusion

The use of portable XRF combined with simple sample preparation tools significantly improves the quality and reliability of field geochemical data. Direct scanning offers rapid anomaly detection while powder analysis enhances repeatability and lab correlation. These methods provide flexible workflows suited to different exploration stages.

Reference

Thermo Fisher Scientific Use of Sample Preparation Tools in Mining and Mineral Exploration Projects Example from a Base Metal Ore Deposit 2012