Using Bauxite Type Samples Followed by XRF Analysis for an Inter-Position Repeatability Study with TheOx® Advanced Instrument

One of the major sources of aluminum in the world is bauxite. Aluminum content and concentrations of other elements such as iron, silicon, and titanium need to be continuously monitored during mine planning, exploration, processing, and quality control as these values are critical to define the value and grade of the bauxite ore. This article evaluates the performance and rapidity of bauxite sample preparation process involving borate fusion and subsequent XRF analysis to determine major and minor elements.

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The glass disks were prepared using a Claisse^® TheOx^® Advanced fusion instrument. The instrument employs electric resistance heating and consists of six fusion positions, providing a throughput of 24 to 30 fusions per hour. It not only delivers an increased sample throughput, but also provides fast fusion temperature ramp up for shorter fusion cycles.

A Panalytical Zetium sequential wavelength dispersive X-ray fluorescence spectrometer equipped with a 2.4 kW Rh-anode Super Sharp Tube (SST R-mAX50) was used to perform XRF measurements.

Global Sample Preparation Method

All samples were prepared using a 1:10 dilution ratio with a LiT/LiM 50/50 flux, pure grade (99.98+%) without non-wetting agents. The time taken for the entire cold-to-cold process was 24 minutes. The flux was weighed directly in the same 95% Pt - 5% Au crucible, wherein the sample was weighed to prevent any material loss which could cause inaccurate results. The sample was fused using a fully automatic TheOx Advanced instrument.

Challenges

• Rapid and accurate sample preparation and sample analysis are required to control exploration, mining and processing of the mineral
• High reproducibility and inter-position repeatability for robust and stable sample preparation

Benefits

• Simple and fast
• High throughput
• Inter-position repeatability and stability
• Precise results

Results

Ten fused disks replicates were prepared on the same fusion position in order to verify the stability of TheOx Advanced instrument. This repeatability test was carried out using the certified reference material (CRM) NIST 698 (Table 1).

Table 1. Results of the sample preparation repeatability test for CRM NIST 698 where 10 fused disk replicates were produced on the same fusion position

Repeatability tests were performed using CRM NIST 698 to examine the inter-position repeatability of the TheOx^® Advanced fusion instrument during the borate fusion process. For a total of twelve replicates, two fused disks replicates were prepared on each fusion position. Then, the average concentrations and relative standard deviation (RDS) were calculated and compared with the expected value of the CRM NIST 698 (Table 2).

Table 2. Results of the sample preparation repeatability test for CRM NIST 698 where two fused disk replicates were produced on each fusion position – for a total of 12 replicates

Conclusion

Considering that sample preparation errors as well as instrumental measurement errors are included in the standard deviation value, it can be shown that highly reproducible disks are produced all along the six positions by the TheOx Advanced instrument.

Hence, elemental analysis using the combination of the TheOx Advanced fusion instrument and a Zetium Minerals edition XRF spectrometer is an effective method to control mining, processing, and quality of bauxite ores. The results confirm that fusion and the consequent benefits of an accurate XRF analysis can be easily achieved, thanks to the productivity and repeatability of the TheOx Advanced instrument.

This information has been sourced, reviewed and adapted from materials provided by Claisse.

For more information on this source, please visit Claisse.