Geological exploration and advanced resource characterisation
General theme: Ore-formation models are developed which allow defining exploration tools, such as geochemical vectors and mineral pathfinders, which can in turn be applied to identify new target areas, like stratigraphic or structural traps. Research focusses on both field work and the integration of analytical techniques such as petrographic, mineralogical and geochemical analyses. This advanced characterisation on a macro- and micro-scale is applied on primary and secondary resources, as a first step in the extraction and recovery of base and critical elements. Due to the often complex mineralogy and/or low content of (critical) metals in primary (minerals, rocks…) and secondary resources (slags, ashes, sludges, concentrates…), a combination of advanced characterisation techniques (e.g. Raman, µ-XRF, LA-ICP-MS, FEG-EPMA, QXRD…) allows to obtain information on both the quantity and distribution of the elements and minerals of interest. This information is for example key to understand and optimise the metal recovery efficiency through particular processes (chemical digestion, thermal treatment….) and to efficiently develop valorisation routes for the residual fractions (see RL4).
Metallogenesis and exploration of ore deposits
Metallogenic models are constructed which are used in the exploration of ore deposits. Two flagship deposits SIM² KU Leuven is currently working on, are: (1) Sediment-hosted Cu-Co deposits in the Central African Copperbelt. The origin of the metals and fluids, the precipitation conditions and the timing of ore formation are integrated in a metallogenic model which allows to constrain target areas for exploration. 2- and 3D models of the ore are constructed to allow exploration at the mine scale and facilitate exploitation; (2) Pegmatite hosted Ta-Sn-W ore deposits quartz vein Sn-W-Au deposits in the Karagwe-Ankole belt (Central Africa). Spatial distribution models of pegmatites and quartz veins combined with newly developed ore-forming models are used to define the control on the occurrence of these ore deposits. The ore-forming models are developed based on extensive field work, mineral and rock characterisation, micro-analytical geochemistry (Raman, LA-ICP-MS and FEG-EPMA) and numerical modelling.
Geometallurgical characterisation of tailings for extraction and recovery
2D and 3D models of the spatial, chemical and mineralogical variability of tailings are developed in combination with quantitative characterisation and distribution analysis of base and critical elements. The most appropriate dissolution method, and if needed, enrichment method for the quantification of the total concentration of the elements is elaborated. The analytical set-up and standardisation and calibration method are optimised. The detailed distribution and the relationship of the ore and host-rock minerals is visualised by optical microscopy, particle mapping analysis (PMA) by the mineral liberation analysis (MLA technology) and by micro-XRF. Both total and sequential extraction, as well as mineralogical characterisation, are used to infer the solid-phase speciation of the elements of interest.
Characterisation of low concentrations of (critical) metals in ores, residues or End-of-Life products by FEG-EPMA-WDS
For low grade ores or residues or for complex End-of-Life products, the use of FEG-EPMA-WDS (Field Emission Gun Electron Probe Micro Analysis – Wavelength Dispersive Spectroscopy) is being applied to quantify based on standards, the concentration of the elements of interest (by point analyses) and their distribution among the phases (by elemental mapping) at the µ-level. Compared to Energy Dispersive Spectroscopy (EDS), WDS has a higher spectral resolution, which allows to differentiate elements with overlapping EDS lines, such as is the case for the REE elements. As such, REE elements, precious metals or (other) critical metals are investigated with FEG-EPMA in slags, sludges… . The FEG-EPMA technique is complimentary to other techniques, such as Raman microscopy, QXRD (mineral quantification) or Mössbauer (chemical bonding), to obtain a complete picture of the material. This information is then valuable in the design of processes to recover the elements of interest or to create a product with the desired properties.
The leading members in this research line are:
Prof. Philippe Muchez is head of the Ore Geology and Geofluids Research Group. He carried out post-doctoral research at the University of Liverpool and at the Vrije Universiteit Amsterdam. Laureate of the Royal Academies for Science and the Arts of Belgium and member of the Royal Academy for Overseas Sciences. Research on the migration of fluids in sedimentary basins and ore-forming processes, i.e. Pb-Zn deposits in Europe, sediment-hosted ore deposits in the Copperbelt (Zambia, DRC) and Nb-Ta-Sn-W-Au deposits in Central Africa.
Prof. Bart Blanpain (RL Leader) leads the HiTemp Group, has more than 20 years of experience in the field of pyrometallurgy including ferrous and non-ferrous metallurgy and slag processing. Bart Blanpain’s Group has an excellent track record in (mainly) strategic basic and applied science projects involving slag/residue valorisation, refractory wear, urban/landfill mining and novel/optimised metallurgical flow sheets (incl. projects with Aperam, ArcelorMittal Sidmar, Umicore, MetalloChimique, Campine, Group Machiels etc.
Prof. Valerie Cappuyns is senior lecturer in environmental science and technology. Her research interests include environmental geochemistry (solid-phase characterisation and leaching of heavy metals from soils, sediments and waste materials), sustainable management of contaminated sites, life cycle analysis, and eco-efficiency.
Niels Hulsbosch is a FWO postdoctoral researcher who focusses on the quantification of differentiation processes in evolved felsic magma systems and their role in the enrichment of critical rare metals, such as lithium, niobium, tantalum, tin and tungsten. Niels Hulsbosch investigates the geochemistry of the bulk, mineral and inclusion record of natural rocks in order to constrain the composition, temperature and pressure of the metal-carrying melts and fluids responsible for the formation of the magmatic-hydrothermal ore deposits. The differentiation processes are quantified on the basis of numerical modelling. His expertise within the group consists of laser ablation–ICP-MS, Raman spectroscopy and cold-seal autoclave experiments on mineral, melt and fluid inclusions.
Dr. Annelies Malfliet is a materials engineer experienced in the field of pyrometallurgy, and coordinator of the Centre for High Temperature Processes and Sustainable Materials Management. Her main domain of expertise is vessel integrity and microscopical characterisation techniques, including FEG EPMA-WDS.
Prof. Jan Elsen is a geologist and his research focuses on the mineralogical characterisation and use of industrial minerals (clays, cement minerals and zeolite deposits with pozzolanic properties). Techniques used include Quantitative X-Ray Diffraction, petrography, electron microscopy and thermal and chemical analysis.