Zetium - Analysis of iron ores using the WROXI widerange oxides application

This data sheet demonstrates the performance of the Zetium - Minerals edition XRFspectrometer in providing accurate and precise iron ore analyses.

Iron ores typically consist of oxides of iron together with gangue minerals like silica, bauxite, alumino-silicates and phosphorous bearing apatite. In addition to the iron ore grade, these gangue minerals influence the price of the iron ore since they affect the smelting process and the quality of the iron and steel.

Zetium Minerals Edition 

Introduction

Iron ores typically consist of oxides of iron together with gangue minerals like silica, bauxite, alumino-silicates and phosphorus-bearing apatite. In addition to the iron ore grade, these gangue minerals influence the price of the iron ore since they affect the smelting process and ultimately the quality of the iron and steel. This data sheet demonstrates the performance of the Zetium - Minerals edition XRF spectrometer in providing accurate and precise iron ore analyses.

Instrumentation

The Minerals edition of the Zetium spectrometer is a fully integrated wavelength dispersive XRF spectrometer, complete with X-Y sample handler and state-of-the-art software. Engineered for excellence in terms of both analytical and operational performance, it has been configured specifically to meet the needs of users in the mining and minerals industries.

The Minerals edition of the Zetium spectrometer can be delivered with a set of 19 synthetic, multi-element wide-range oxides (WROXI) standards and an application template for the analysis of major and minor elements in fused beads. Using PANalytical’s unique FP algorithm in our SuperQ software, the WROXI application can determine concentrations of up to 21 common oxides in a wide range of rocks, ores and minerals.

WROXI can be used either as a primary fused bead calibration or to verify customer in-house standards for pressed powder applications.

Figure 1. Comparison of certified and measured concentrations in iron ore samples 

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Sample preparation and measurement details

Fourteen certified reference materials (CRMs), including some of the BCS- and ECRM-series from the Bureau of Analysed Samples, were prepared and analyzed as routine samples to test accuracy of the WROXI calibrations.

The WROXI standards and CRMs used in this study were prepared using 0.9 g of sample fused in 9.0 g flux (66 % lithium tetraborate, 34 % lithium metaborate) and cast into 40 mm diameter fused beads.

The measurement program used to obtain the data presented had a total measurement time of nine minutes (Table 1). These times can, however, be adjusted according to the required precision.

Table 1. Total measurement time (peak + background) 

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Accuracy

The accuracy of the Minerals edition of the Zetium spectrometer using WROXI standards and the SuperQ (FP) calibration model for major and minor element analyses  in iron ores was very good. This is illustrated in Figure 1 for  Fe2O3, SiO2 and P2O5 where measured values are compared with certified values for all CRMs.  A  further  comparison  of 11 oxides in an iron ore CRM (BCS 303) is provided in Table 2. Loss on ignition (LOI) is accurately determined as a balance compound by the SuperQ FP algorithm.

Table 2. A comparison of certified and measured concentrations for an iron ore CRM BCS 303

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Precision

The precision, repeatability and reproducibility of the Zetium spectrometer is excellent, not only in the short term, but also for measurements carried out over a longer period of 14 days (Table 3). The data presented in Table 3 did not require any form of drift correction. For comparison, the counting statistical error (CSE) expressed in concentration units is also shown in Table 3. The CSE is theoretically the minimum possible error and the data demonstrates the inherent stability of the Zetium spectrometer.

Table 3. Reproducibility (12 measurements over 14 days) for iron ore (BCS 301) 

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Conclusion

Elemental analysis with XRF is already the key to the control of quality and production processes in the mining of iron ore deposits. The Minerals edition of the Zetium spectrometer with WROXI and the SuperQ FP approach further extends the advantages of XRF as the best analytical method for reliable iron ore analysis. It has been demonstrated that analyses are accurate and precise and the method benefits from a simple fusion sample preparation. Furthermore, the stability of the system is such that individual calibrations can be used for months. Time-consuming re-standardizations are unnecessary and the resultant data are highly consistent over time.

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