Analyzing Manganese Ore with the ARL OPTIM’X XRF Spectrometer

Manganese is a transition metal utilized in several exciting applications, such as manufacturing alloys (like stainless steel) and batteries. Manganese is particularly important in Li-ion battery cathodes, where it is used to stabilize nickel manganese cobalt (NMC) materials, enhancing performance and maintaining the battery’s safety.

Mining and refining manganese ore is the first step in manganese production, irrespective of end application. Identifying the ore composition enables the employment of appropriate refinement techniques that produce the purest materials possible. Because high-quality ores require less refining, manganese ore prices can vary substantially. As a result, proper ore characterization is vital for precise distribution and processing.

X-Ray fluorescence (XRF) spectroscopy is a widely used analytical technique for determining the chemical makeup of ores. Because it is rapid, non-destructive and demands minimal sample preparation, XRF is a popular approach in mining and refining applications. In this article, a Thermo Scientific^™ ARL OPTIM’X^™ XRF Spectrometer is utilized to quickly investigate multiple elements/oxides in ores.

Given the large quantities of manganese ore extracted each year, every minute saved in characterization can substantially impact overall throughput.

Figure 1. Thermo Scientific ARL OPTIM’X XRF Spectrometer with its 13-position sample loader. Image Credit: Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers

Instrumentation

The ARL OPTIM’X XRF Spectrometer is a wavelength dispersive XRF (WDXRF) spectroscopic instrument with low operating and maintenance expenses. The ARL OPTIM’X Spectrometer is equipped with a Thermo Scientific^™ SmartGonio^™ Goniometer, allowing it to cover the entire elemental range from fluorine (₉F) to americium (₉₅Am).

The spectrometer is available at two power levels: 50 W and 200 W. Generally, the 200 W version often acquires data 2.5× faster than the 50 W version. The 50 W version was used for this article.

The ARL OPTIM’X Spectrometer requires neither external nor internal water cooling and offers a 10× better spectral resolution than a traditional energy-dispersive XRF (EDXRF) instrument, as well as higher precision and stability. It performs consistently with elements such as sodium (₁₁Na), magnesium (₁₂Mg), and even fluorine (₉F).

Analytical Conditions

Table 1. Analytical conditions for manganese ore characterization. Source: Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers

The intensity data for 12 elements in each manganese ore sample were collected using the SmartGonio Goniometer on the 50 W ARL OPTIM’X Spectrometer (Table 1). The entire analysis took eight minutes. The measurement time can be fine-tuned further for specialized purposes.

With the 200 W instrument, total counting time might be reduced by a factor of 2.5 while maintaining accuracy and precision. When the 200 W ARL OPTIM’X Spectrometer is utilized, the total analysis time is reduced to less than four minutes.

Sample Preparation

Four manganese ore certified reference materials (CRMs) were used for calibration. With a sample-to-flux ratio of 1:10, samples were fused into beads without ignition. The fusion mixture was given an ammonium nitrate oxidizer. The concentration ranges of the several oxides covered by the calibration are shown in Table 2. For each compound, R² and standard error of estimates (SEE) values were calculated.

The sample preparation as fused beads eliminates any grain size or mineralogical effects that could interfere with the X-Ray fluorescence analysis. As a result, excellent analysis accuracy was achieved, particularly for major and minor elements/oxides.

Trace element identification is more challenging due to sample dilution, as trace levels in the actual fused bead are 10 times lower than in the original sample. As a result, extended counting times may be used for trace element determination, when necessary. When best trace element determination is required, samples are prepared as pressed pellets.

Table 2. Concentration ranges and calibration parameter values for manganese ore components. Source: Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers

* Data is the average of 4 manganese ore CRMs

Figure 2. Two of the fused beads used for the calibration. Image Credit: Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers

Calibration

Calibration curves were plotted to connect elemental X-Ray intensity to oxide amounts (Figure 3). When just one form of each oxide is present in the sample, X-Ray fluorescence may detect individual elements and the results can be directly linked to the oxide forms.

Figure 3. Calibration curves for a selection of oxides found in manganese ore. Image Credit: Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers

Validation and Precision

To validate the calibration, two manganese ore reference materials (170a and 171) were used (Table 3). CRM reference values are compared to the average of 10 replicate CRM analyses. The repeatability of the 10 replicates for each CRM is revealed in Tables 4 and 5.

Table 3. Analysis of reference manganese ores with the ARL OPTIM’X Spectrometer. Source: Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers

Table 4. Repeatability of manganese ore (170a) analysis using the ARL OPTIM’X Spectrometer. Source: Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers

Table 5. Repeatability of manganese ore (171) analysis using the ARL OPTIM’X Spectrometer. Source: Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers

Conclusion

This article demonstrated the ARL OPTIM’X Spectrometer’s effectiveness for manganese ore sample analysis. This compact equipment enables quick and reliable analysis as well as great repeatability. The 50 W ARL OPTIM’X Spectrometer requires an eight-minute total analytical time. The sample preparation as fused beads dilutes the sample 10 times, implying that the trace element levels are extremely low in the actual fused beads.

This explains the poor precision of traces, particularly for V₂O₅. Measurement time can be fine-tuned even further for specialized purposes, such as increasing counting time to increase precision for trace or significant elements.

The 200 W version of the ARL OPTIM’X Spectrometer reduced total counting time by a factor of 2.5 while maintaining the same accuracy and precision. In this situation, the overall analysis time, including loading and pumping time, would be less than four minutes.

This information has been sourced, reviewed and adapted from materials provided by Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers.

For more information on this source, please visit Thermo Fisher Scientific - Elemental Analyzers and Phase Analyzers.