Developing Applications of Mineral-Specific X-ray Diffraction

Dr Graeme Hansford has invented a novel X-ray diffraction (XRD) technique which enables the enhancement of the diffraction signal from a specific mineral within a mixture. This technique has multiple potential commercial applications, primarily in metallurgy and mining. It can be implemented using relatively low-cost X-ray technology as a handheld or portable device or in a production line configuration. The technique is suited to applications in which the user is interested in one key mineral or phase, such as an important impurity. The method can be used to determine the presence or absence of this phase, and for quantification.

The primary targeted application at this stage is the quantification of retained austenite in steel production. The heat treatment of steels is mainly aimed at producing martensite which is an iron phase supersaturated with carbon. Martensite has generally desirable properties for steel applications, for example it is has a high tensile strength. Any austenite which does not convert to martensite (hence 'retained') may have benefits to the intended application or, more commonly, it may be deleterious. Measurement of the amount of retained austenite is therefore crucial for process and quality control purposes in the manufacture of steel. XRD methods are standard for retained austenite quantification, but current instruments cost in excess of £100k and either require destructive preparation of the sample or have a cumbersome measurement head which must be carefully positioned relative to the analysis area. In contrast, an instrument based on the phase-specific XRD technique can have a point-and-shoot format similar to handheld X-ray fluorescence instruments and is likely to cost ~£30k. This novel technique has the potential to disrupt the existing market in retained austenite measurement.

Another application example is the detection and quantification of quartz in iron ores. Quartz is commonly present as an impurity in iron ores and determines the optimum processing method because it is a hard mineral. A quick and accurate estimate of the quartz content in ores would allow rapid decision making at mines and mineral processing plants, saving costs through streamlining of operations and avoiding costly and wasteful errors. The mineral-specific XRD technique offers a compact and low-cost method of making such measurements.