In this interview, AZoMining talks to Mathieu Bauer about handheld X-ray fluorescence spectrometry and how it is becoming increasingly important in the mining industry as it aids in maximizing the productivity of processes.
What is handheld XRF and how does it work?
Handheld XRF is a method of elemental analysis that detects and measures the concentration of elements from magnesium to uranium in solids and liquids. The instrument utilizes an X-ray tube that irradiates the sample surface, causing the emission of secondary element-specific secondary X-rays called fluorescence. Those emitted radiations are then detected using a semi-conductor detector, summed, and processed to obtain a spectrum. The information from the spectrum is then used to calculate the weight concentrations of the elements, which are displayed in real-time on the analyzer's screen.
How has handheld X-ray fluorescence (XRF) spectrometry become pivotal in mining?
The mining industry adopted handheld XRF on a large scale around 20 years ago. This adoption has been driven by its capability of generating real-time measurements to support field decisions and its ease of use and deployment. This has resulted in considerable productivity gains and cost savings compared to lab analysis.
Where is handheld XRF used in the mining workflow?
Handheld XRF is used in greenfield explorations to locate anomalies in soils and outcrops. The technology is also used in the second exploration phase to analyze drilling cores to locate mineralization and decide whether to continue or stop drilling. Handheld XRF is also utilized in mining operations to control the grade of extracted ore and monitor pollution around mining sites.
Image Credit: Thermo Fisher Scientific
What are the benefits of handheld XRF for the mining industry?
The first obvious benefit of handheld analyzers is the ability to carry and operate those instruments in the field, often in remote places and harsh environments. Furthermore, the fact that comprehensive and accurate geochemical results are generated in real-time will enable instant decision-making without sending samples to the lab and waiting days, weeks, or even months for the results. Handheld XRF also enables the collection of a high density data of geochemical data, monitoring trends in composition changes, and creating 2D and 3D grids and models of the deposits. I also want to mention the very low cost per analysis and the overall gains in terms of productivity vs. traditional field exploration sample collection.
Can you share some examples illustrating the capabilities of handheld XRF?
Handheld XRF can analyze many commodities, including most base metals ores, at levels ranging from a few parts per million to 100 %, depending on the element. A first example is the use of handheld XRF to analyze drilling cores of metal sulfide ore and measure the concentration of zinc, lead, copper, and silver to assess the viability of the deposit.
Another example is grade control of commodities and industrial minerals such as bauxite, in addition to alumina, the sought-after commodity, handheld XRF measures so-called penalty elements such as silica, iron, or titanium oxide, which can, when present at high concentrations, complicate the refining process of aluminum oxide.
A third example is assessing heavy metal contamination in soils around mining sites or smelters. Here, handheld XRF is a reliable tool to detect low levels of heavy metals such as lead, cadmium, zinc, copper, nickel, and chromium. The data are then used in geographic information systems to map the site pollution.
How accurate is handheld XRF for mining applications?
By order of importance, the accuracy of handheld XRF measurements will depend on the sample preparation, the targeted elements, and their concentration levels. Overall accuracy will increase with increasing atomic numbers and high concentrations. Using the analyzer in “point and shoot” mode, in other words, aiming the analyzer at a rock face, will mostly yield purely qualitative results due to the heterogeneity and roughness of the rock. Reducing rock samples to homogenous powders in the field with a crusher and mortar will significantly improve accuracy. Furthermore, applying lab-type sample preparation, including drying the sample before grinding it to a fine powder, will yield near-lab-quality results.
What differentiates handheld XRF from lab XRF analysis?
Due to the higher tube power and the difference in hardware and technology, benchtop and stationary instruments are generally more sensitive and precise than handhelds. Also, in the lab, samples undergo a more extensive preparation so that the achieved accuracy using stationary instruments is usually higher. Furthermore, lab instruments can detect a few more elements, such as sodium and fluorine, and some stationary instruments may even detect oxygen and carbon. The best results are usually achieved by combining handheld and lab-generated data. In this approach, handheld instruments perform many short measurements in the field and monitor relative trends in composition changes. In contrast, lab analysis is used more for QA/QC purposes and to determine the absolute values with high accuracy on a small subset of samples that have been previously selected using the handheld analyzer.
What differentiates today’s handheld XRF analyzers from 10 years ago?
The main difference between modern XRF instruments and those 10 years ago is the dramatic increase in sensitivity for light elements such as magnesium and aluminum, thanks to the adoption of detectors using graphene windows. Overall, analytical performance improvement was achieved thanks to the higher power of X-ray tubes and larger detectors. Also, hardware features such as integrated GPS, an intuitive user interface, and the flexibility of the software enable users to customize more settings and better integrate the generated results into their workflow.
What is the general return on investment for handheld XRF for mining applications?
The return on investment of handheld XRF is generally very fast and can be calculated considering several factors:
- The efficiency and the acceleration of the exploration process thanks to a higher density of on-site measurements allowing the identification of anomalies and drill targets
- Increased productivity and decreased remobilization cost in the exploration process compared to traditional field exploration, which collects samples that are sent to the lab with a long turnaround time.
- The screening and pre-selection of samples sent for lab analysis and thus reduction by a factor of 2 to 10 of external assay and freight cost
- The enhanced mine productivity is achieved by guiding the extraction of ore thanks to instant results.
- The initial investment is lower, and the running costs are lower in terms of maintenance and labor for handheld XRF vs. lab technologies.
Can you explain what benefits the Niton XL5 Plus Analyzer brings to Mining?
The Thermo ScientificTM NitonTM XL5 Plus is a small, light, and powerful handheld XRF analyzer. With its small footprint, it can be carried in a backpack with accessories such as tripods and test stands and deployed in remote places. For geochemical analyses, the Niton XL5 Plus uses a 5-watt tube that automatically adjusts the current to maximize the count rate, providing users with innovative analytical performance for detecting traces of heavy metals and fast-detecting light elements. With an IP54 rating, the Niton XL5 Plus is suitable for operation in hostile mining environments. It is equipped with integrated GPS and Wifi connectivity, simplifying data collection and mapping export.
What other solutions does Thermo Fisher offer for the mining workflow?
Besides handheld XRF, Thermo Fisher Scientific offers a comprehensive portfolio of analytical solutions to address the mining industry's most pressing geochemical analysis needs. This includes benchtop and stationary XRF instruments, inductively coupled plasma optical emission spectrometry (ICP-OES) for lab elemental analysis, conveyor belt analyzers for online elemental analysis, and X-ray diffraction (XRD) for identifying mineralogy.
About Mathieu Bauer 
Mathieu Bauer holds a PhD in analytical chemistry from the University of Hamburg and has over 20 years of experience working with spectroscopy, including handheld X-ray fluorescence (HHXRF).
Mathieu is currently working as a senior application scientist and associate product manager at Thermo Fisher Scientific.
This information has been sourced, reviewed and adapted from materials provided by Thermo Fisher Scientific – Handheld Elemental & Radiation Detection .
For more information on this source, please visit Thermo Fisher Scientific – Handheld Elemental & Radiation Detection .
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