Using Portable XRF Analysis for Geochemical Mapping in Mining
The data collected during grade control processes helps mining geologists conduct quantitative geochemical analysis of metal concentrations. With this data, one can create composite maps of elemental distributions within a sample and determine where the best targets are located. Geochemical maps used in underground mining applications can be used to see an anomaly or trend, make the most efficient and economical drilling and excavation decisions, and ensure that mining plans will yield a sufficient return on investment.
The Geological Survey of Sweden reports that their geochemical mapping “focuses on researching the natural levels of metals and other important elements in soils. The information shows, for example; areas where gold is present, where there is a lack of important elements such as phosphorus and magnesium, or a risk of too high natural levels of arsenic or cadmium.” To improve the scientific basis for public and private natural resource and land‐use decisions, The Geological Society of America (GSA) supports comprehensive geologic mapping on local, state, and national scales.
Traditional mining sample analysis often involves a costly and time-consuming process of sending samples to off-site laboratories and waiting days, even weeks, for the results. Portable XRF instruments are often used in geochemical mapping because they can be carried anywhere at the mine site to collect hundreds, even thousands of analyses. These handheld analyzers can provide laboratory-grade sample analysis for rapid feedback during drilling operations, or to prequalify samples for off-site lab analysis. There is no additional cost to the mining operation for the number of point-and-shoot ‘scans’ that are taken.
XRF (X-ray fluorescence) is a non-destructive analytical technique used to determine the elemental composition of materials. XRF analyzers determine the elemental composition of a sample by measuring the fluorescence (or secondary) X-ray emitted from elements in a sample when those are excited by a primary X-ray source. Each of the elements present in a sample produces a set of characteristic X-ray lines (“a fingerprint”) that is unique for that specific element, which is why XRF spectroscopy is an excellent technology for qualitative analysis and quantitative determination of material composition.
Most analyzers can be operated virtually anywhere on site and easily accommodate a wide variation of samples with little or no preparation, whether they are in the form of drill core, bagged samples, or cut directly from the mine face. Most of the leading XRF analyzers come equipped with GPS and data management options for real-time assessment of geochemical data in the field. Some analyzers can simultaneously operate an internal and connect to an external GPS. High resolution external GPS provide greater accuracy when needed. When both systems are enabled and connected, the external GPS overrides the internal system. If the external GPS shuts down, the internal GPS automatically becomes the primary system and provides coordinates.
By using these portable XRF analyzers, geologists can obtain large volumes of exploration data for mapping and financial reporting as well as help identify areas for infill sampling, drilling or more detailed investigation. Whether one is looking for base metals or precious metals, portable X-ray fluorescence (XRF) analyzers provide mining exploration assay data within seconds, allowing for real-time ore deposit modeling, and more efficient mining operations.
by : Tim Johnson – Thermo Fisher Scientific
