Publications of Eric Pirard
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See detailRecycling Oriented Characterization of PGMs from Spent Automotive Catalysts (ACCs)
Hassan, Ali ULiege; Bouzahzah, Hassan ULiege; Lambert, Fanny et al

Conference (2021, June 02)

Platinum Group Metals (PGMs) are key critical metals for Europe, that is dependent on export from the main producing countries, mainly South Africa and Russia, which together are responsible for 75 to 80 ... [more ▼]

Platinum Group Metals (PGMs) are key critical metals for Europe, that is dependent on export from the main producing countries, mainly South Africa and Russia, which together are responsible for 75 to 80% of the PGM world mine supply. On the demand side, the EU legislation on pollution emission standards has pushed the use of automotive catalytic converters (ACCs) in vehicles, making that the manufacturing of ACCs by far the largest PGMs (Pt, Pd & Rh) consuming application. The concentrations of PGMs in ACC urban mines is much higher (>2000 ppm) than conventional mines in South Africa and Russia (2-10 ppm) and therefore recycling of ACCs presents an important source of PGMs for sustainably supply and reduced environmental footprint. Hydrometallurgical recovery methods are seen as sustainable alternatives to well established and industrially applicable pyrometallurgical techniques. However, research efforts have not yet led to industrialization. A better understanding of complex ACC material in terms of morphology, liberation, metallurgical associations, metal speciation and metal liberation should improve the process performances. Recycling oriented characterization of different types of ACCs available on the market was performed using SEM-EDS. These included cordierite based diesel oxidation (DOC) and three-way catalysts (C-TWC), silicon carbide based diesel particle filter (DPF), and metallic based three way catalyst (M-TWC). Structural design differences were noticed between different catalyst types and all ACCs contained complex compositional complexity. Washcoat distribution in DPF was found to be different than other ACCs. Catalysts were found to contain secondary deposition layers of poisons with varying degree of contamination of Zn, Ca, P, K, S, Pb, etc. PGM particles were found to be uniformly distributed in the washcoat. They were also trapped in the poisoning layer, attached to or contained within the washcoat components such as ceria and alumina. PGM and washcoat components were heavily sintered and grown in size. Sintering had blocked the active surfaces/PGM liberation by loss of surface area which also results in reduction of porosity. SEM-EDS proved to be a powerful tool to analyze several phenomena that have happened to ACCs over the operational lifetime. The information obtained at nanoscale provided for better understanding of ACCs and variance within ACC urban deposit useful for subsequent pretreatment or hydrometallurgical PGM recovery routes. [less ▲]

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See detailTalc schist deposits from central Cameroon: Mineralogical and physico-chemical characterization
Woguia, Damaris Laure ULiege; Fagel, Nathalie ULiege; Pirard, Eric ULiege et al

in Journal of African Earth Sciences (2021), 178

Talc schist deposits are reported in central Cameroon region, and different alteration zones were determined depending on differences related to the texture and color of the host rock. For the purpose of ... [more ▼]

Talc schist deposits are reported in central Cameroon region, and different alteration zones were determined depending on differences related to the texture and color of the host rock. For the purpose of determining mineralogical and physicochemical characteristics of talc schist, a total of 45 samples from the sites studied were collected and analyzed using an array of physico-chemical methods. Talc schist samples are mainly composed of variable amount of talc associated with plagioclase and clay minerals. Three groups of mineral association were determined: i) talc with small amount of chlorite and traces of kaolinite, ii) talc with high amount of chlorite, iii) variable amount of talc with plagioclase and clay minerals. The talc schist samples have homogeneous grain-sizes and are classified as silty sand or sandy silt. The occurrence of Ni and Cr in the talc schists are consistent with the composition of the talc deposits formed in relation to ultramafic rocks. The genesis of talc is due to hydrothermal fluid circulation in ultramafic rocks, attested by the occurrence of S and P. [less ▲]

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See detailPenser le cycle des métaux : clé de voûte pour une économie plus renouvelable
Pirard, Eric ULiege

Scientific conference (2021, March 27)

Nous qualifions de renouvelables les énergies du vent et du soleil, mais qu’en est-il des métaux qui sont les indispensables vecteurs de la conversion vers une énergie électrique ? La croissance ... [more ▼]

Nous qualifions de renouvelables les énergies du vent et du soleil, mais qu’en est-il des métaux qui sont les indispensables vecteurs de la conversion vers une énergie électrique ? La croissance exponentielle de la production des métaux, amorcée depuis plus d’un siècle, ne va certainement pas fléchir dans les prochaines décennies. L’extraction des ressources va se poursuivre à un rythme effréné pour satisfaire les besoins de la transition écologique, que ce soit pour la production et le stockage d’énergie, pour nos envies de mobilité, ou encore pour nos besoins de communication numérique. N’est-il pas urgent, par géomimétisme, d’apprendre à penser le cycle des métaux et à jeter les bases d’une économie plus circulaire ? Les défis qui attendent nos sociétés sont de mettre en place les règles favorisant un cycle de vie plus durable, d’adapter le comportement des consommateurs, mais aussi de repenser nos produits car ils seront la mine urbaine des générations futures. [less ▲]

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See detailRessources Métalliques et Environnement
Pirard, Eric ULiege

Scientific conference (2021, February 12)

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See detailCloud and Cloud-Shadow Detection for Applications in Mapping Small-Scale Mining in Colombia Using Sentinel-2 Imagery
Ibrahim, Elsy ULiege; Jiang, Jingyi; Lema, Luisa et al

in Remote Sensing (2021), 13(4 736),

Small-scale placer mining in Colombia takes place in rural areas and involves excavations resulting in large footprints of bare soil and water ponds. Such excavated areas comprise a mosaic of challenging ... [more ▼]

Small-scale placer mining in Colombia takes place in rural areas and involves excavations resulting in large footprints of bare soil and water ponds. Such excavated areas comprise a mosaic of challenging terrains for cloud and cloud-shadow detection of Sentinel-2 (S2A and S2B) data used to identify, map, and monitor these highly dynamic activities. This paper uses an efficient two-step machine-learning approach using freely available tools to detect clouds and shadows in the context of mapping small-scale mining areas, one which places an emphasis on the reduction of misclassification of mining sites as clouds or shadows. The first step is comprised of a supervised support-vector-machine classification identifying clouds, cloud shadows, and clear pixels. The second step is a geometry-based improvement of cloud-shadow detection where solar-cloud-shadow-sensor geometry is used to exclude commission errors in cloud shadows. The geometry-based approach makes use of sun angles and sensor view angles available in Sentinel-2 metadata to identify potential directions of cloud shadow for each cloud projection. The approach does not require supplementary data on cloud-top or bottom heights nor cloud-top ruggedness. It assumes that the location of dense clouds is mainly impacted by meteorological conditions and that cloud-top and cloud-base heights vary in a predefined manner. The methodology has been tested over an intensively excavated and well-studied pilot site and shows 50% more detection of clouds and shadows than Sen2Cor. Furthermore, it has reached a Specificity of 1 in the correct detection of mining sites and water ponds, proving itself to be a reliable approach for further related studies on the mapping of small-scale mining in the area. Although the methodology was tailored to the context of small-scale mining in the region of Antioquia, it is a scalable approach and can be adapted to other areas and conditions. [less ▲]

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See detailSmall-scale surface mining of gold placers: Detection, mapping, and temporal analysis through the use of free satellite imagery
Ibrahim, Elsy ULiege; Lema, Luisa; Barnabé, Pierre ULiege et al

in International Journal of Applied Earth Observation and Geoinformation (2020), 93

Informal small-scale mining is spread in many countries and provides livelihood to numerous families in rural areas yet often with devastating social and environmental impacts. The alluvial gold mining ... [more ▼]

Informal small-scale mining is spread in many countries and provides livelihood to numerous families in rural areas yet often with devastating social and environmental impacts. The alluvial gold mining process in Colombia, also known as placer mining, involves excavations using heavy machinery and creates large footprints of bare soil and mining ponds. The very dynamic nature of this extractive activity and its spread in rural and remote areas make its mapping and monitoring very challenging. The use of freely available satellite data of the Copernicus programme provides great new possibilities to study these activities and provides stakeholders integrated data to better understand the spatial and temporal extent of the activities and mitigate affected areas. The objective of this work is to assess the potential of Sentinel-2 data to identify mining areas and to understand the dynamics in landcover change over a study area located at the border of the municipalities of El Bagre and Zaragoza in Bajo Cauca, Colombia. The study utilizes a classification approach followed by post-processing using field knowledge on a set of images from 2016 to 2019. Sequential pattern mining of classified images shows the likelihood of certain annual and seasonal changes in mining-impacted landcover and in the natural vegetation. The results show a slight reduction in the detected mining areas from 2016 to 2019. On the other hand, there are more mining activities in the dry season than in the wet season. Excavated areas of bare soil have a 50% chance to remain in excavation over the considered period or they transition to non-vegetated areas or mining ponds. Vegetation loss due to the extractive activities corresponds to about 35% while recovered vegetated areas are 7% of the total excavated areas in June 2019. An analysis of abandoned sites using NDVI shows that it takes a much longer period than the one considered in this paper for potential natural recovery of vegetation. Finally, the work was disseminated among stakeholders and the public on MapX (https://mapx.org), an online open platform for mapping and visualizing geospatial data on natural resources. It is a pilot study the will be the basis of the analysis of more regions in the department of Antioquia. [less ▲]

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See detailLe laminoir à zinc de Tilff au XIXème siècle
Pirard, Eric ULiege

in Archéo-contact Vieil Esneux (2020), 56

Le laminoir du nouveau moulin de Tilff acquis par la société de la Vieille-Montagne en 1837 et transformé en laminoir à feuilles de zinc a été en activité jusqu'en 1953. Son histoire, étroitement associée ... [more ▼]

Le laminoir du nouveau moulin de Tilff acquis par la société de la Vieille-Montagne en 1837 et transformé en laminoir à feuilles de zinc a été en activité jusqu'en 1953. Son histoire, étroitement associée à celle du village, est bien documentée au travers des rapports d'ingénieurs consignés dans les archives de la société et est bien illustrée grâce aux remarquables aquarelles de A. Maugendre. [less ▲]

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See detailBetterGeoEdu: European project for popularizing science through video games
Godfirnon, Maxime ULiege; Pirard, Eric ULiege; Evrard, Maxime ULiege et al

Conference given outside the academic context (2020)

Presentation of the BetterGeoEdu project, aiming to use the BetterGeo mod (or modification) on the Minecraft game, giving it a more realistic geology. We discuss a series of aspects of the game that the ... [more ▼]

Presentation of the BetterGeoEdu project, aiming to use the BetterGeo mod (or modification) on the Minecraft game, giving it a more realistic geology. We discuss a series of aspects of the game that the mod modifies, and consider elements that can be clarified or modified in order to provide tools for teachers in teaching geology to primary school students. [less ▲]

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See detailLa quadrature de l'économie circulaire
Pirard, Eric ULiege

Conference given outside the academic context (2020)

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See detailOù sont les métaux pour les technologies du futur?
Pirard, Eric ULiege

Conference given outside the academic context (2020)

Pendant des siècles l'homme s'est contenté d'exploiter les énergies renouvelables. Il se contentait également d'élaborer des objets simples au départ de sept métaux abondants et faciles à travailler. La ... [more ▼]

Pendant des siècles l'homme s'est contenté d'exploiter les énergies renouvelables. Il se contentait également d'élaborer des objets simples au départ de sept métaux abondants et faciles à travailler. La mécanisation et la maîtrise des énergies fossiles a engendré un cortège d'innovations technologiques sans précédent. Il est désormais impensable de se passer des équipements mobiles et de renoncer à se déplacer au quotidien. Mais, la transition écologique tant vantée a un coût. Elle mobilise de très nombreuses ressources métalliques et induit une activité minière comme jamais auparavant dans l'histoire de l'humanité. A travers cet exposé, nous verrons comment la mise en place d'une véritable économie circulaire des métaux est la seule voie possible vers un développement raisonné. [less ▲]

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See detailMicroscopie corrélative et traitement d'images pour la réalisation de cartographies minéralogiques automatisées
Pirard, Eric ULiege; Bouzahzah, Hassan ULiege

Scientific conference (2019, June 04)

La réalisation de cartographies minéralogiques de sections de roches par le biais de microscopes électroniques à balayage (MEB) équipés d’analyseurs EDX s’est largement répandue au cours des dernières ... [more ▼]

La réalisation de cartographies minéralogiques de sections de roches par le biais de microscopes électroniques à balayage (MEB) équipés d’analyseurs EDX s’est largement répandue au cours des dernières années (QEM-SCAN ; MLA ; TIMA ; INCA-MINERAL ; MINERALOGIC ;…). Toutefois, cette technique reste très largement tributaire de l’expertise de l’opérateur et de sa connaissance préalable du contexte minéralogique. L’utilisation de la microscopie corrélative (optique + BSE + EDX) permet d’envisager le développement de stratégies d’analyse plus rapides et plus précises. Les développements les plus récents en classification et en intelligence artificielle devraient également permettre d’obtenir des cartographies plus exactes tout en minimisant l’intervention humaine. [less ▲]

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See detailTowards Automated Mineralogy 4.0
Pirard, Eric ULiege; Bouzahzah, Hassan ULiege

Scientific conference (2019, May 28)

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See detailDisponibilité durable des matières premières pour la transition énergétique
Pirard, Eric ULiege

Conference given outside the academic context (2019)

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See detailDEVELOPMENT OF ADVANCED IMAGING TECHNIQUES FOR REAL TIME PARTICLE SENSING IN MINERAL PROCESSING AND RECYCLING
Leroy, Sophie ULiege; Barnabé, Pierre ULiege; Dislaire, Godefroid ULiege et al

in Rosenkranz, Jan (Ed.) Konferens i Mineralteknik (2019, February 06)

With the ever increasing pressure for digitization and optimization of mineral processing operations, there is a growing need for real-time monitoring solutions providing informations about individual ... [more ▼]

With the ever increasing pressure for digitization and optimization of mineral processing operations, there is a growing need for real-time monitoring solutions providing informations about individual particles and their nature. This paper briefly reviews existing on-stream analytical techniques and stresses the need for “single particle sensing systems”. A series of technologies developed at ULiège, GeMMe, are presented together with a small case study. [less ▲]

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See detailMineral recognition of single particles in ore slurry samples by means of multispectral image processing
Leroy, Sophie ULiege; Pirard, Eric ULiege

in Minerals Engineering (2019)

Mineral processing relies heavily on the differential behaviour of particles in slurries. In order to monitor the performance of separation units such as flotation cells or hydrocyclones it is helpful to ... [more ▼]

Mineral processing relies heavily on the differential behaviour of particles in slurries. In order to monitor the performance of separation units such as flotation cells or hydrocyclones it is helpful to develop on stream characterization tools providing information on particle size distribution and mineralogy. This paper describes an experimental set-up designed for the multispectral imaging of particles in water suspensions. The imaging system enables the acquisition of multispectral images. Images are processed to provide analysis on hundreds of particles in a few seconds. The prototype was used to acquire images of a series of pure mineral samples. Pure minerals powdered samples were suspended in water in order to mimic mineral slurries. The data are processed by means of machine learning methods. It is demonstrated that selected minerals can be discriminated from one another based on their optical properties. It is also shown that the optical properties measured with the system are somehow related to well-documented optical features such as specular and diffuse reflectance. The technology developed in this work sets the basis for on line monitoring of ore slurries with reasonably simple mineralogy. [less ▲]

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See detailMineralogical reconciliation of cobalt recovery from the acid leaching of oxide ores from five deposits in Katanga (DRC)
Santoro, Licia; Tshipeng, Steev; Pirard, Eric ULiege et al

in Minerals Engineering (2019), 136

In mines in Katanga region of the Democratic Republic of Congo (DRC), cobalt is commonly recovered from oxy-hydroxide minerals (e.g. heterogenite, asbolane) using a sulfuric acid leach under reducing ... [more ▼]

In mines in Katanga region of the Democratic Republic of Congo (DRC), cobalt is commonly recovered from oxy-hydroxide minerals (e.g. heterogenite, asbolane) using a sulfuric acid leach under reducing conditions. However, most of the leaching operations show yields of Co, below 80% so the current study focused on determining the reasons for the recovery shortfall. A range of samples were investigated comprising a detailed mineralogical characterization of five concentrate and leached samples from different mine plants in the Katanga region: namely Kalukuluku, Mutanda, Mabaya, Kamwali and Fungurume mines. The analyses were carried out prior to and after leaching treatments using a combination of chemical (ICP-AES) and mineralogical techniques (XRD, automated mineralogy, SEM-EDS and X-ray mapping). The results revealed that heterogenite and asbolane occur in samples both prior to and after leaching: this confirms the ineffective leaching of these minerals or/and the presence of Co-bearing refractory minerals and other phases inhibiting the diffusion of leachate. SEM-EDS and X-ray mapping of leached samples showed that both heterogenite and asbolane are commonly finely intergrown with clays and Fe-oxy-hydroxides (FOH). These outcomes are in agreement with automated mineralogy results for the Co deportment, showing that Co is mainly hosted in: (a) pure heterogenite particles, (b) heterogenite intergrown with other minerals, (c) fine-grain heterogenite (≤1µm) enclosed in clays, and (d) clays or/and FOH adsorbing Co in the structure. The Co recovery inefficiency is a result of the mineralogical complexity of the ores, making the current processing strategy sub-optimal. In conclusion the two main reasons for the incomplete recovery are: firstly mineral liberation issues and secondly the presence of un-recoverable elemental Co within the structure of refractory phases [less ▲]

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See detailMatières Premières Critiques : Quelles pistes pour réduire notre dépendance ?
Pirard, Eric ULiege

Conference (2018, June 20)

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See detailRemote Sensing and Mineral Resources
Pirard, Eric ULiege

Conference (2018, June 11)

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See detailThe role of microscopy in the Circular Economy
Pirard, Eric ULiege; Bouzahzah, Hassan ULiege; Castroviejo, Ricardo et al

Scientific conference (2018, May 16)

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See detailL’approvisionnement en métaux critiques: Importance, stratégies et impact
Pirard, Eric ULiege

Conference given outside the academic context (2018)

De l’Âge de la Pierre à l’Âge du Lithium, nous n’avons eu de cesse d’exploiter les ressources naturelles et de perfectionner nos outils. Baignant dans une abondance de technologies, nous ne nous soucions ... [more ▼]

De l’Âge de la Pierre à l’Âge du Lithium, nous n’avons eu de cesse d’exploiter les ressources naturelles et de perfectionner nos outils. Baignant dans une abondance de technologies, nous ne nous soucions plus guère des matières premières qui les rendent possibles et ignorons souvent que leur production est aux mains d’économies émergentes. Depuis 2010, avec son « Initiative Matières Premières », l’Europe se préoccupe de sa situation de forte dépendance vis-à-vis de l’approvisionnement en métaux. Entre les métaux de base et les métaux précieux sont tout d’un coup apparus des métaux qualifiés de « critiques » ( à ne pas confondre avec les Terres Rares ). La criticité est une notion multiple qui possède au moins trois dimensions : géologique, technologique et géopolitique. En prenant l’exemple de quelques métaux emblématiques, l’orateur mettra en évidence les causes d’une possible criticité. Puis, il s’interrogera sur les stratégies possibles pour mitiger notre dépendance et montrera que, tout compte fait, la criticité n’est sans doute pas là où l’on s’y attend le plus ! Enfin, il décrira de qui est fait à ce sujet en Région Wallonne, avec d’importants programmes d’innovation technologique qui associent universités, centres de recherche et entreprises, et permettent à ces acteurs de se positionner au cœur des réseaux européens sur l’économie circulaire des métaux. [less ▲]

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