Automated Quantitative Mineralogy Optimized for Simultaneous Detection of (Precious/Critical) Rare Metals and Base Metals in A Production-Focused Environment

Abstract

Automated Scanning Electron Microscopy (ASEM) systems are applied in the mining industry to quantify the mineralogy of the ore feed and products. With society pushing towards sustainable mining, this quantification should be comprehensive and include trace minerals since they are often either deleterious or potential by-products. Systems like QEMSCAN® offer a mode for trace mineral analysis (TMS mode); However, it is unsuitable when all phases require analysis. Here, we investigate the potential of detecting micron-sized trace minerals in fieldscan mode using the QEMSCAN® system with analytical settings in line with the mining industry. For quality comparison, analysis was performed at a mining company and a research institution. This novel approach was done in full collaboration with both parties. Results show that the resolution of trace minerals at or below the scan resolution is difficult and not always reliable due to mixed X-ray signals. However, by modification of the species identification protocol (SIP), quantification is achievable, although verification by SEM-EDS is recommended. As an add-on to routine quantitative analysis focused on major ore minerals, this method can produce quantitative data and information on mineral association for trace minerals of precious and critical metals which may be potential by-products in a mining operation.

The interrelation of petrographical propeties of rocks and their crushing and grindig features : A literature review

“…where AGSI is the average grain size index; P is the total percentage of grain size and k is the number of the classification interval [13]. Automated Scanning Electron Microscopy (ASEM) systems are wide-spread and routinely applied in the mining industry [17]. These methods provide fast and reliable quantification of the mineralogy and texture, of which the two most prominent are the Quantitative Evaluation of Mineralogy by Scanning electron microscope (QEMSCAN®) system and the Mineral Liberation Analyzer (MLA) system.…”

“…In the case of the QEMSCAN, the minerals are identified based on their X-ray elementspectra and the BSE brightness is used to distinguish the particle from the surroundings. In the case of MLA, the BSE brightness is used to define the particles which subsequently are classified by one X-ray spectrum per particle [17,18]. The QEMSCAN is suitable for the quantitative chemical measurement of individual mineral grains and the generation of mineral maps, while the MLA is suitable for the identification of minerals and mineral aggregates, and the quantification of mineral abundance, particle size and liberation.…”

Editorial for Special Issue “Applications of SEM Automated Mineralogy: From Ore Deposits over Processing to Secondary Resource Characterization”

“…An article by Warlo et al [20] deals with a novel approach to overcome difficulties when trace minerals are detected within a single measurement when they are accompanied by the major ore minerals. Small grain sizes of the trace minerals complicate the task as they induce mixed X-ray signals.…”

Automated petrography analysis by QEMSCAN® of a garnet-staurolite schist of the San Lorenzo Formation, Sierra Nevada de Santa Marta massif

“…QEMSCAN ® creates phase assemblage maps of a specimen surface scanned by a high-energy accelerating electron beam along a predefined raster scan pattern. It preferentially uses low-count energy-dispersive X-ray mapping for mineral classification, which is done by comparison of the X-ray element-spectrum to existing dataset of mineral phases (Warlo et al, 2019). The elemental composition in combination with back-scattered electron (BSE) brightness and X-ray count rate information is converted into mineral phases (Gottlieb et al, 2000).…”