XRF Analysis of Ta-Nb (Coltan), Sn, and W

Tantalum (Ta), niobium (Nb), and tin (Sn) are commonly used in high-end technology products.

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Tantalum, known for its durability and high fusion point, is used in electronics for capacitors found in mobile phones, computers, and digital cameras. It is also used in alloys for the aerospace and nuclear industries. Niobium is primarily used in the steel industry and the production of super-alloys and superconductors. Tin, valued for its low fusion point, has been used for thousands of years in various applications.

The world’s current resources are struggling to meet the growing demand for tantalum. Meanwhile, demand for niobium, already a scarce metal, is projected to continue rising annually. Since 2006, demand for tin has also surged, driven by its increased use in solders after the ban on lead (Pb) in welding products in some countries.

Locating and verifying viable sources of tantalum, niobium, and tin is a challenging task that requires advanced tools, such as handheld X-ray fluorescence (XRF) analyzers.

Application

Geologically, Ta, Nb, and Sn are found in late-stage magmatic formations, such as pegmatites and high-temperature veins. Minerals like tantalite ((FeMn)Ta₂O₆), columbite ((FeMn)Nb₂O₆), and cassiterite (SnO₂) are common sources of these elements.

Tantalite is frequently found alongside columbite, forming a mineral mix known as columbite-tantalite, or coltan. These heavy minerals can be eroded, transported by water, and concentrated through gravity separation, leading to the formation of placer deposits, which are key sources for mining Ta, Nb, and Sn in several regions.

Handheld X-ray fluorescence (HHXRF) analyzers are essential tools for both prospecting and monitoring the quality of these metals during mining. Given the high trading value of these elements, accuracy in evaluating ore concentrates is especially important.

Handheld XRF Analyzers in Mining

Handheld XRF analysis offers a fast and accurate method for obtaining results with minimal to no sample preparation. It can be applied at various stages of mining, including grassroots exploration, extraction, ore grade control, and even environmental assessments.

The handheld Thermo Scientific^™ Niton^™ XL2 Plus Analyzer, the Thermo Scientific^™ Niton^™ XL3t GOLDD+ Analyzer, and the Thermo Scientific^™ Niton^™ XL5 Plus Analyzer all provide real-time, accurate elemental analysis with exceptional efficiency for companies involved in all stages of mining and exploration.

These advantages are made possible by Thermo Fisher's high-power X-ray tube with dynamic current adjustment and advanced silicon drift detectors.

Over 10,000 Niton handheld XRF analyzers are currently in use across the global mining industry. These instruments can analyze a wide range of elements, from magnesium (Mg) to uranium (U). Figure 1 shows an example of results obtained from a handheld XRF analysis.

Methodology

For this investigation, high-grade samples were analyzed using a Niton XL3t GOLDD+ handheld XRF analyzer, and the results were compared to laboratory methods such as ICP and AAS.

The analyses were conducted using the Mining mode on the handheld analyzer, which employs a "fundamental parameters" algorithm capable of quantifying over 30 elements without the need for user calibrations.

If necessary, accuracy can be further improved by performing a simple post-calibration adjustment using previously characterized lab samples.

Results

The coefficient of determination (R²) measures how closely data sets correlate, with a perfect correlation yielding an R² value of 1. The study demonstrates a strong correlation between the data from the Niton XL3t GOLDD+ XRF analyzer and the lab methods (see Figure 2).

Conclusions

Many minerals appear as dark gray to black grains, which can sometimes resemble fine-grain coltan. The high correlation between assay results from the handheld Niton XL3t GOLDD+ and laboratory data confirms the handheld XRF's ability to accurately identify high- and low-grade coltan concentrates within seconds.

The Niton XL5 Plus, Niton XL3t GOLDD+, or Niton XL2 Plus XRF analyzers provide fast, precise elemental analysis throughout all stages of the mining process, from exploration to extraction and processing of base metals and industrial minerals.

Figure 1. Example result for an analysis of a Coltan concentrate mineral sample using the Niton XL3t GOLDD+ XRF analyzer. Image Credit: Thermo Fisher Scientific – Handheld Elemental & Radiation Detection

Figure 2. Correlation diagrams for Ta, Nb, and Sn analyzed using the Niton XL3t GOLDD+ analyzer. Image Credit: Thermo Fisher Scientific – Handheld Elemental & Radiation Detection

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This information has been sourced, reviewed and adapted from materials provided by Thermo Fisher Scientific – Handheld Elemental & Radiation Detection.

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