References of "Pirard, Eric"
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See detailCharacterization of fine aggregates in concrete by different experimental approaches
He, Huan; Courard, Luc ULg; Pirard, Eric ULg et al

in Proceedings 13 Int. Congress for Stereology (2011, October)

Being its major component, aggregate can occupy up to three-quarter of the volume of concrete. The structure of aggregate formed in hardened state impacts largely on mechanical and durability properties ... [more ▼]

Being its major component, aggregate can occupy up to three-quarter of the volume of concrete. The structure of aggregate formed in hardened state impacts largely on mechanical and durability properties of concrete. On another hand, physical characteristics of aggregate are primarily assumed to be relevant to granular behavior of aggregate. Therefore, characterization of aggregate is of high relevance to concrete studies. In this study, different types of fine aggregate used in concrete, namely river sand and crushed limestone, are selected for morphological characterization. Traditional sieve analysis and laser diffraction method are employed for separation and size analysis of specimens. Different types of fine aggregate samples with comparable size ranges are then analyzed by two advanced dry (static) and wet (dynamic) image analysers. These new analysers are especially suitable for characterization of fine particles, which is difficult by traditional image analysis equipments. Size and shape characteristics of different fine aggregates will be revealed by different experimental methods. The results on different parameters for shape characterization will be compared and discussed [less ▲]

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See detailTextural Descriptors for Multiphasic Ore Particles
Perez-Barnuevo, Laura; Pirard, Eric ULg

in Proceedings 13 Int. Congress for Stereology (2011, October)

The monitoring of mineral processing circuit based on particle liberation analysis using quantitative image analysis has become a routine technique within the last decades. But liberation indices are ... [more ▼]

The monitoring of mineral processing circuit based on particle liberation analysis using quantitative image analysis has become a routine technique within the last decades. But liberation indices are computed as weight proportions, which is not convenient when complex texture ores are treated by flotation. In these cases, liberation has to be computed as phase surface available to reactants, and the type of intergrowth between phases has to be characterized so as to determine the possibility of liberation. To achieve this characterization some indices have been developed in terms of 2D phase contact and mineral surfaces exposed. These indices, as well as indices suggested by other authors and additional measures, have been explored on simple synthetic textures ranging from single to multiple inclusions and single to multiple veins. The ability of these parameters to discriminate the various textures is analyzed [less ▲]

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See detailSensitivity of particle size and shape parameters with respect to digitization
Pirard, Eric ULg; Dislaire, Godefroid

in Proceedings 13 Int. Congress for Stereology (2011, October)

The growing success of image analysis based instruments for particle characterization demonstrates the importance of size and shape analysis in operations involving particulate materials. ISO norms for ... [more ▼]

The growing success of image analysis based instruments for particle characterization demonstrates the importance of size and shape analysis in operations involving particulate materials. ISO norms for particle sizing using image analysis are being elaborated to clarify nomenclature and measurement principles. But despite this, there is still a lack of understanding of how the digital representation of a particle affects different size and shape parameters. It is the purpose of this paper to explore the magnitude of estimation errors of a series of size and shape parameters from different digital image representations of a single particle. These images are simulated from grey level images of black particles presenting a Gaussian transition towards their white background. Particles themselves are generated from analytical functions sampled by digital grids with variable densities, positions and orientations. Results of inscribed disk, elongation, circularity, roughness, roundness, etc. are plotted as a function of grid density (magnification) with error bars corresponding to the scattering of results for variable thresholds, grid translations and rotations As a conclusion, confidence intervals are given for parameters as a function of magnification and the most sensitive and robust methods of shape analysis are put forward. [less ▲]

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See detailOptical analysis of particle size and chromite liberation from pulp samples of a UG2 ore regrinding circuit
Leroy, Sophie ULg; Dislaire, Godefroid; Bastin, David ULg et al

in Minerals Engineering (2011), 24

Since the early seventies high chromite and low base metal sulphide (BMS) contents of the UG2 reef imposes technological challenges to mineral processors and extractive metallurgists. Forty years later ... [more ▼]

Since the early seventies high chromite and low base metal sulphide (BMS) contents of the UG2 reef imposes technological challenges to mineral processors and extractive metallurgists. Forty years later, particle size distribution and size by size mineralogy are considered as key factors to the continuous improvement of the UG-2 ore metallurgy. With the successful development of ultra fine grinding technologies, a compromise has to be found between fine grinding to achieve platinum group minerals liberation and to avoid the overgrinding of gangue minerals, especially chromite gangue which is detrimental in smelting process. Indeed, fine chromite grains, despite of being naturally hydrophobic mineral, can be recovered in flotation concentrate by entrainment. In addition, overgrinding also increase liberation of naturally floatable gangue (talc) which contaminate the concentrate and need to be controlled during flotation. In this paper, innovative techniques of single particle image analysis from both dry and wet samples have been tentatively used to assess the chromite particle size distribution and the chromite grade of samples taken from a secondary milling circuit. Preliminary results demonstrate excellent potential for online particle imaging making use of both the particle geometry (size, shape) and the optical properties (translucency). [less ▲]

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See detailLes ressources du sous-sol bolivien : mirage ou véritable El Dorado ?
Pirard, Eric ULg

in Gresea Echos (2011), 67

Made In Bolivia : Le sud se développe en solo... Le cas du Lithium

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See detailAn Experimental Approach to Link Powder Physical Properties to 3D Particle Shape
Califice, Arnaud ULg; Lumay, Geoffroy ULg; Vandewalle, Nicolas ULg et al

in Particulate Systems Analysis 2011 (2011, September)

A series of samples have been characterized by 3D image analysis (using X-Ray microtomography). The samples consist of blends of metallic particles: steel shot abrasives (“balls”), steel fibres and ... [more ▼]

A series of samples have been characterized by 3D image analysis (using X-Ray microtomography). The samples consist of blends of metallic particles: steel shot abrasives (“balls”), steel fibres and angular steel grit particles. The blends were systematically prepared in different proportions of the raw products. Various shape and size parameters were measured on the particles: equivalent volume diameter (dV), maximum inscribed sphere diameter (dIN), particle length (maximum Feret diameter), particle elongation (El), particle flatness (Fl) etc. The results are expressed as statistical shape and size parameters, expressed both as volume and number weighted distributions. The blends have been tested for compaction using a cylindrical container which experiences a series of 500 free falls over a height of 3mm. The compaction dynamics was monitored using a sensor that measures the evolution of the solid volume fraction as a function of the tap number. From the obtained compaction curve, the Hausner ratio and a flowability index were extracted. The same blends have also been analysed using a rotating drum at different rotation speeds to analyze the evolution of the flowing angle. As the system is based on the analysis of a time sequence of 50 images (separated by 0.5 sec) it is possible to measure the intermittent character of the powder flow. The resulting measure is a cohesive index of the powder. The results obtained from physical testing were systematically plotted as a function of various statistical indices of the shape and size distributions in order to reveal correlations between particle shape properties and physical behaviour. Some clear trends appeared, demonstrating the influence of particle shape on powder physical properties. [less ▲]

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See detailTechnological Characterisation of West African Iron Ores in Order to Predict their Performance in the Beneficiation Process
Dubron, Liesbet ULg; Pirard, Eric ULg; Pirson, Arnaud

in Proceedings Iron Ore 2011 (2011, July)

This study details a mineralogical and textural characterisation of West African iron ores with an emphasis on their behavior during mineral processing. By means of both qualitative and quantitative ... [more ▼]

This study details a mineralogical and textural characterisation of West African iron ores with an emphasis on their behavior during mineral processing. By means of both qualitative and quantitative characterisation, a simulation of the beneficiation process applied to these iron ores is performed. A series of different analytical tools are used, including: X-Ray Diffraction (XRD) for qualitative mineralogical analysis; qualitative optical microscopy (phase identification, description of micro-textures) and (semi)quantitative optical microscopy (counting of particles, phases and textural types); and chemical analyses. All the information provided by these analytical methods are combined into a quantitative mineralogical and textural analysis, here called “modal analysis”, which enables us to simulate the capability of West African iron ores to be beneficiated by magnetic and gravimetric separation techniques. [less ▲]

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See detailReal-Time Image Analysis of Iron Ore Cores and Drill Chips to Complement Spectral Measures
Belligoï, Thomas; Ramanaidou, Eric; Pirard, Eric ULg

in Proceedings of Iron Ore 2011 (2011, July)

Diamond cores and drill chips provide the only direct physical evidence for ore containing rocks. Early characterisation of cores and drill chips is important as it provides critical information for ... [more ▼]

Diamond cores and drill chips provide the only direct physical evidence for ore containing rocks. Early characterisation of cores and drill chips is important as it provides critical information for downstream processing. Traditional characterisation techniques include visual logging by a geologist or analytic and spectroscopic methods but they are time consuming and can miss some important textural or geomechanical features. The goal of this work is to evaluate the application of image analysis to iron ore cores and drill chips and to suggest improvements to existing core-scanning and chip monitoring systems. Two samples of massive ore differing by their mineralogy and texture, as well as two different batches of drill chips, have been imaged and analysed. Results are compared in function of the imaging system and the classifi cation algorithms. As a conclusion, despite the necessity for more testing and improvements in calibration and lighting, it is obvious that image analysis technologies can bring a lot of useful information in the perspective of a geometallurgical mapping of the deposit. [less ▲]

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See detailUse of environmental isotopes to infer flow in the highly exploited aquifer system of the Diass region (Senegal)
Madioune, Diakher Hélène; Faye, Serigne; Dassargues, Alain ULg et al

Poster (2011, March 14)

The Diass horst multilayered aquifer constitutes a complex hydrogeological system. But stable isotopes are illustrated to be powerful tools for clarifying the origin of recharge water, and the groundwater ... [more ▼]

The Diass horst multilayered aquifer constitutes a complex hydrogeological system. But stable isotopes are illustrated to be powerful tools for clarifying the origin of recharge water, and the groundwater dynamics due to high exploitation of the system. Used with 3H and 14C, data confirms that most of the investigated groundwater are palaeowaters. Pumping has an impact on groundwater flow evidenced by the different water isotope compositions that illustrates the transient conditions of the system. Mixing of old waters and recently recharged (tritiated) waters occurs in some exploited boreholes, indicates lateral flow to the pumping field through the main groundwater flow directions. [less ▲]

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See detailParticle Size and Shape Characterisation - Current Technology and Practice
Hart, Jarrod; Zhu, Yingdan; Pirard, Eric ULg

in Christidis, George (Ed.) Advances in the Characterization of Industrial Minerals (2011)

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See detailImage analysis for advanced characterization of industrial minerals and geomaterials
Pirard, Eric ULg; Sardini, Paul; Christidis, Georges

in Advanced Characterization of Industrial Minerals (2011)

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See detailParticle packing of concrete containing blended cement
He, Huan ULg; Courard, Luc ULg; Pirard, Eric ULg

Conference (2010, September 20)

Physical particle packing is becoming a hot topic in concrete technology as more and more types of granular materials are used in concrete either for ecological or for engineering purposes. Aggregate is ... [more ▼]

Physical particle packing is becoming a hot topic in concrete technology as more and more types of granular materials are used in concrete either for ecological or for engineering purposes. Aggregate is used as concrete’s skeleton, whereby the particles are stabilized by the cementitious matrix. Packing efficiency governs the spatial characteristics of this structure and thereby influences concrete’s properties. Fine-grained sand can be used to further improve density of the aggregate structure. The particulate cement is also frequently blended by fine mineral admixtures to influence performance of the paste and the properties of the matured concrete. The so-called filler effects increase packing density of the blended cement and possibly reduce water demand. High performance characteristics require suitable blending materials of proper properties (fineness, shape, chemical components, etc.). A number of theoretical packing models have been proposed for prediction of packing characteristics and the resulting concrete properties. A minimum voids ratio has been mathematically derived for certain particle size distributions. This allowed establishment of some optimum graded mixtures for concrete production. On the other hand, the computer simulation approach provides a powerful tool for simulating particle packing. Computational concrete (compucrete) has been developed for a wide range of research purposes. Application of computer simulation to particle packing offers a promising perspective in concrete technology; it provides a proper representation of the heterogeneous concrete material, and renders the possibility of studying the effects of a wide range of technological parameters. In this study, an advanced DEM will be utilized for investigate the packing properties of admixtures blended cement. This new-developed system is capable of packing simulations of arbitrary-shaped particles. Experimental shape analysis of each identical group of particles provides fundamental references of shape simulation strategy. Finally, computer simulation structures of blended cement paste both in fresh and hardened states will be compared with the experimental approach. Correlation of particle packing characteristics and properties of blended cement paste will be analyzed and discussed. Optimization of blending efficiency and improvement of concrete properties are pursued using packing modeling. [less ▲]

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See detailA history of early copper exploration in Katanga (D.R. Congo)
Pirard, Eric ULg

in Proceedings INHIGEO 2010 (2010, July)

The latest archeological findings suggest that malachite outcrops have been mined as early as the Vth century A.C. in Garangaze a province known nowadays as Katanga [1]. The pre-Bayeke tribes used to ... [more ▼]

The latest archeological findings suggest that malachite outcrops have been mined as early as the Vth century A.C. in Garangaze a province known nowadays as Katanga [1]. The pre-Bayeke tribes used to seasonally mine these outcrops and cast copper hansas (crosses) that were used as exchange goods and have been found all over the African continent even reaching Europe as early as the XVIth century through trade with the Portuguese and the Dutch Oud West Indisch Compagnie. The first explicit mention of copper in European texts is said to date back to March 22nd 1798 in a report made by pombeiros (afro-portuguese metis) to the hence governor of Rios de Sena (Mozambique) Francesco Jose Maria Lacerda [2]. Katanga has long remained as the most inaccessible region of the African continent. Despite attempts made by Livingstone until his death in 1873, by Cameron in 1874 and by Thomson in 1878, it was considered to remain for long out of reach [less ▲]

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See detailInfluence of particle flatness and elongation on size distributions obtained from laser diffraction, static and dynamic image analysis.
Califice, Arnaud ULg; Michel, Frédéric ULg; Dislaire, Godefroid et al

in World Congress on Particle Technology (2010, April)

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See detail3D and 2D particle image analysis of rock chips generated by core scratch tests.
Pirard, Eric ULg; Limam, Sami; Califice, Arnaud ULg et al

in World Congress on Particle Technology (2010, April)

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See detailProcess mineralogy and automated phase identification in mixed copper ores at Kansanshi (Zambia)
Kottgen; Bastin, David ULg; Dufrane, Florent et al

Conference (2010)

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See detailQuantitative Microtexture Analysis of Carbonate Rocks Using Bireflectance Imaging
Jaimes Contreras, Rafael Antonio ULg; Pilawski, Dimitri; Califice, Arnaud ULg et al

in Proceedings IAMG 2010 (2010)

Microtextural analysis of rocks has been addressed by several authors as an essential means to better understand the natural genesis of the material. But, it is also of paramount importance to those who ... [more ▼]

Microtextural analysis of rocks has been addressed by several authors as an essential means to better understand the natural genesis of the material. But, it is also of paramount importance to those who try to predict the geotechnical or industrial behaviour of a rock under many forms of solicitation (mechanical, thermal, etc.). Quantitative modal (phase) analysis using point counting has already been discussed in depth by authors such as Chayes more than fifty years ago. Nowadays, automated image analysis with millions of pixels is easily available and improves statistical accuracy provided the classification step is correctly performed. Spitefully the assignment of a pixel to a given mineral phase or to a given crystal is often poorly satisfactory and remains the bottleneck of a fully automated textural analysis. Methods using a manual rotation of a polarizer in transmitted light microscopy have been developed by Starkey and Samantaray (1993) and further automated and improved by Fueten (1997). These allow to better delineate individual crystals in a thin section due to contrast in birefringence. In this paper a similar technique using multiple orientations of a polarizer in reflected light microscopy has been used to contrast individual crystals in carbonated rocks. The maximum and minimum grey levels registered for each pixel allow for computing a bireflectance image whose variance is a good indicator of the misalignment of cristallographical orientations in the section. Moreover, the maximum of the reflectance gradient obtained for each orientation generates a good image of the grain boundaries and the presence of pores. This last one is quantitatively analysed using the intercept method to estimate the mean and variance of the grain size distribution. The paper presents a quantitative comparison of several different microtextures. [less ▲]

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