SOLSA: a revolution in combined sonic drilling and on-line-on-mine-real-time analyses

Combined mineralogical and chemical analyses on drill cores are highly demanded by mining and metallurgical companies to speed up exploration, mining and define geometallurgical parameters for beneficiation. Furthermore, high quality coherent and complete drill cores are needed to obtain reliable analyses for more accurate geomodels, resource and reserve estimates. At present, analyses are done by exploiting only a single technique, such as hyperspectral imaging, XRF or LIBS. The coupling of different analytical instruments is still a technological challenge. The SOLSA project, sponsored by the EU-H2020 Raw Material program, targets to construct an expert system coupling sonic drilling with XRF, XRD, hyperspectral imaging and Raman spectroscopy. This paper will present the 4-years project in progress, a general, almost mid-term, state-of-the-art

Combined XRF, XRD, SEM-EDS, and Raman Analyses on Serpentinized Harzburgite (Nickel Laterite Mine, New Caledonia): Implications for Exploration and Geometallurgy

International audienceDifferent techniques have been combined to determine the crystallography and the chemical composition of serpentinized harzburgite sampled in a drill core coming from the lower part of the New Caledonia ophiolite. Specifically, this serpentinized harzburgite is the common bedrock of most of the nickel laterite mines in New Caledonia. Most of the minerals present in serpentinized harzburgite were analyzed by Raman spectroscopy and XRD. In this study, Raman spectroscopy has been applied for the first time to estimate the nickel content in lizardite, forsterite, talc, and goethite. The analyses confirm that the major serpentine minerals show two varieties: (1) Ni-bearing lizardite and (2) Ni-free lizardite. Furthermore, Ni-rich forsterite, enstatite, Ni-rich talc, sepiolite, periclase (MgO), and quartz were detected. Additionally, Raman spectroscopy evidence minor phases not detected by XRD: anatase, rutile, pyrite, hematite, chromite, magnesiochromite, and Ni-rich goethite. Our results show that the Ni substitution is only present in lizardite exhibiting turbostratic-stacking disorder. This finding has potential for being used as an exploration tool using short-wave-infrared spectroscopy online or as a portable instrument, and for defining geometallurgical parameters for processing these complex ores

Challenges in coupled on-line-on-mine-real time mineralogical and chemical analyses on drill cores

The SOLSA project aims to develop an innovative on-line-on-mine-real-time expert system, combining sonic drilling, mineralogical and chemical characterization and data treatment. Ideally, this combination, highly demanded by mining and metallurgical companies, will speed up exploration, mining and processing. In order to evaluate the instrumental parameters for the SOLSA expert system, portable and laboratory analyses have been performed on four samples with contrasting lithologies: siliceous breccia, serpentinized harzburgite, sandstone and granite. More precisely, we evaluated the influence of the surface state of the sample on the signals obtained by portable X-Ray Fluorescence (pXRF) for chemistry and portable Infra-Red spectroscopy (pIR) for mineralogy. In addition, laboratory Raman spectroscopy, X-Ray Diffraction (XRD), XRF and ICP-OES laboratory analyses were performed to compare surface bulk mineralogical and chemical analyses. This presentation highlights (1) the importance of coupling chemical and mineralogical analytical technologies to obtain most complete information on samples, (2) the effect of the sample surface state on the XRF and IR signals from portable instruments. The last point is crucial for combined instrumental on-line sensor design and the calibration of the different instruments, especially in the case of pXRF

3D Imaging on heterogeneous surfaces on laterite drill core materials

The SOLSA project aims to construct an analytical expert system for on-line-on-mine-real-time mineralogical and geochemical analyses on sonic drilled cores. A profilometer is indispensable to obtain reliable and quantitative data from RGB and hyperspectral cameras, and to get 3D definition of close-to-surface objects such as rheology (grain shape, grain size, fractures and vein systems), material hardness and porosities. Optical properties of minerals can be analyzed by focusing on the reflectance. Preliminary analyses were performed with the commercial scan control profilometer MI-CRO-EPSILON equipped with a blue 405 nm laser on a conveyor belt (depth resolution: 10 μm; surface resolution: 30x30 μm2 (maximum resolution; 1m drill core/4 min). Drill core parts and rocks with 4 different surface roughness states: (1) sonic drilled, (2) diamond saw-cut, polished at (3) 6 mm and (4) 0.25 μm were measured (see also abstract Duée et al. this volume). The ΜICRO- EPSILON scanning does not detect such small differences of surface roughness states. Profilometer data can also be used to access rough mineralogical identification of some mineral groups like Fe-Mg silicates, quartz and feldspars). Drill core parts from a siliceous mineralized breccia and laterite with high and deep porosity and fractures were analyzed. The determination of holes’ convexity and fractures) is limited by the surface/depth ratio. Depending on end-user’s needs, parameters such as fracture densities and mineral content should be combined, and depth and surface resolutions should be optimized, to speed up “on-line-on-mine-real- time” mineral and chemical analyses in order to reach the target of about 80 m/day of drilled core

Efficient long-term open-access data archiving in mining industries

Efficient data collection, analysis and preservation are needed to accomplish adequate business decision making. Long-lasting and sustainable business operations, such as mining, add extra requirements to this process: data must be reliably preserved over periods that are longer than that of a typical software life-cycle. These concerns are of special importance for the combined on-line-on-mine-real-time expert system SOLSA (http://www.solsa-mining.eu/) that will produce data not only for immediate industrial utilization, but also for the possible scientific reuse. We thus applied the experience of scientific data publishing to provide efficient, reliable, long term archival data storage. Crystallography, a field covering one of the methods used in the SOLSA expert system, has long traditions of archiving and disseminating crystallographic data. To that end, the Crystallographic Interchange Framework (CIF, [1]) was developed and is maintained by the International Union of Crystallography (IUCr). This framework provides rich means for describing crystal structures and crystallographic experiments in an unambiguous, human- and machine- readable way, in a standard that is independent of the underlying data storage technology. The Crystallography Open Database (COD, [2]) has been successfully using the CIF framework to maintain its open-access crystallographic data collection for over a decade [3,4]. Since the CIF framework is extensible it is possible to use it for other branches of knowledge. The SOLSA system will generate data using different methods of material identification: XRF, XRD, Raman, IR and DRIFT spectroscopy. For XRD, the CIF is usable out-of-the-box, since we can rely on extensive data definition dictionaries (ontologies) developed by the IUCr and the crystallographic community. For spectroscopic techniques such dictionaries, to our best knowledge, do not exist; thus, the SOLSA team is developing CIF dictionaries for spectroscopic techniques to be used in the SOLSA expert system. All dictionaries will be published under liberal license and communities are encourage to join the development, reuse and extend the dictionaries where necessary. These dictionaries will enable access to open data generated by SOLSA by all interested parties. The use of the common CIF framework will ensure smooth data exchange among SOLSA partners and seamless data publication from the SOLSA project

Going Sonic.

April 2019, Volume 2 Issue 2: 65-69

Going Sonic.

April 2019, Volume 2 Issue 2: 65-69

Sediment-hosted Mn-U and Fe deposits from exploration to processing.

January 2019, Number 44, p. 1-4

Subduction-derived fluid/melt percolation in lithospheric mantle revealed by metasomatic orthopyroxene in peridotites from French Massif Central

International audienceSecondary orthopyroxene (OPX2) replacing olivine is known in xenoliths within arc lavas (e.g. [1-3] and references therein), and in some ultramafic complexes [4, 5]. It is interpreted as resulting from interactions between fluids or melts released by the subducting slab and the mantle wedge. The olivine is destabilised according to: olivine + Si-rich fluid/melt OPX2 (± minor clinopyroxene) + less-siliceous fluid/melt. However, metasomatic orthopyroxene has been rarely observed in continental context in xenoliths or ultrahigh-pressure complexes [6, 7]. This contribution reports for the first time the presence of metasomatic orthopyroxene in mantle xenoliths from the French Massif Central (FMC). The samples are fresh spinel lherzolites from the Mont Coupet volcano (Devès, FMC). OPX2 has three modes of occurrences: mode 1, in thin veins (< 30µm) cross-cutting or rimming primary olivine; mode 2, at the contact between primary olivine and clinopyroxene; mode 3, in large (a few hundred µm) reaction pockets that contain secondary olivine, clinopyroxene, small patches of glass with plagioclase laths and numerous vesicles. Small pores (< 2µm) line the contact between OPX2 and the other phases. OPX2 (modes 1, 2) contains rare rounded inclusions of Cl-apatite. The composition of OPX2 is distinct from that of primary orthopyroxene and similar in the three modes of occurrences. The main difference is its lower content in Al2O3: 1.7-2.7 wt. % compared to 2.9-4.4 wt. % in primary orthopyroxene, depending on the sample. It also contains less Cr2O3 (<0.2 wt. %) and TiO2 (<0.1 wt. %), is CaO richer (0.3-0.7 wt. %) and has similar mg# (90-91). OPX2 in modes 1 and 2 formed at similar pressure (1.6-1.7 GPa) but higher temperature (1200 °C / 980 °C) than primary phases. OPX2 in mode 3 also forms in the mantle but at a lower depth (1085 °C and 1.4 GPa). The presence of pores and inclusions of Cl-apatite are interpreted as the signature of Si-rich and Cl-bearing metasomatic fluids in the formation of OPX2 in modes 1 and 2. In the vesicles-bearing pockets (OPX2, mode 3) the metasomatic agent must contain other elements in addition to silica, and is likely to be a volatile-rich hydrous Si-melt. The low Al of OPX2 content is similar to that of subduction-related metasomatic orthopyroxene (references above), as well as experimentally-formed orthopyroxene after olivine [8]. Thus, we suggest that the metasomatizing fluids and melts involved at Mont Coupet are similar to slab-derived components. The metasomatic event occurred in the mantle, as indicated by the P and T condition, and may be in relation with the Variscan subduction. A subduction-related metasomatism in the lithospheric mantle beneath the FMC has been recently envisaged by different authors [9, 10]