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See detailMineralogical characterization of a gold ore through a computational mineral liberation analysis
Rojas, Ronald; Torem, Mauricio; Merma, Antonio et al

in Proceedings of the XV Balkan Mineral Processing Congress - BMPC 2013 (2013, June)

This work presents the mineralogical characterization of a very low-grade Brazilian gold ore. The aim is to provide mineralogical information and liberation distribution characteristics in order to assess ... [more ▼]

This work presents the mineralogical characterization of a very low-grade Brazilian gold ore. The aim is to provide mineralogical information and liberation distribution characteristics in order to assess a possible economic byproducts recovery. This may include a direct tailings processing or alternative gold processing routes. It was studied the distribution of all minerals present in the ore, mainly the gangue minerals. Distribution based on speciation, particle size, mineralogical association and liberation determined through the use of the automated analytical Scanning Electron Microscope technique (MLA). The study is complemented with chemical and mineralogical analysis by XRF and XRD respectively. It also includes particle size analysis, gravity separation and magnetic separation tests. Chemical analysis showed that the ore consists essentially of SiO2 (62.33%), Al2O3 (15.95%), Fe2O3 (7.66%), K2O (4.60%), TiO2 (1%) and others (8.46%). Based on this analysis, the study was mainly directed to the characterization of titanium-bearing minerals due to its economic importance. Therefore, minerals as ilmenite, rutile and anatase were identified as the Ti-bearing minerals. After a meticulous analysis of the results, it was identified a possible route for processing TiO2, taking into account the mineralogical and liberation point of view. [less ▲]

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See detailMineralogical gradients associated with alvinellids at deep-sea hydrothermal vents
Zbinden, M.; Le Bris, N.; Compère, Philippe ULg et al

in Deep-Sea Research Part I-Oceanographic Research Papers (2003), 50(2), 269-280

Alvinella pompejana and Alvinella caudata live in organic tubes on active sulphide chimney walls at deep-sea hydrothermal vents. These polychaete annelids are exposed to extreme thermal and chemical ... [more ▼]

Alvinella pompejana and Alvinella caudata live in organic tubes on active sulphide chimney walls at deep-sea hydrothermal vents. These polychaete annelids are exposed to extreme thermal and chemical gradients and to intense mineral precipitation. This work points out that mineral particles associated with Pompeii worm (A. pompejana and A. caudata) tubes constitute useful markers for evaluating the chemical characteristics of their micro-environment. The minerals associated with these worm tubes were analysed on samples recovered from an experimental alvinellid colony, at different locations in the vent fluid-seawater interface. Inhabited tubes from the most upper and lower parts of the colony were analysed by light and electron microscopies, X-ray microanalysis and X-ray diffraction. A change was observed from a Fe-Zn-S mineral assemblage to a Zn-S assemblage at the millimeter scale from the outer to the inner face of a tube. A similar gradient in proportions of minerals was observed at a decimeter scale from the lower to the upper part of the colony. The marcasitc/pyrite ratio of iron disulphides also displays a steep decrease along the few millimeters adjacent to the external tube surface. The occurrence of these gradients indicates that the microenvironment within the tube differs from that outside the tube, and suggests that the tube wall acts as an efficient barrier to the external environment. (C) 2003 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailMineralogical signatures of Lake Baikal sediments: Sources of sediment supplies through Late Quaternary
Fagel, Nathalie ULg; Thamo-Bozso, Edith; Heim, Birgit

in Sedimentary Geology (2007), 194(1-2), 37-59

The mineralogical composition of Late Quaternary sediments was investigated in three piston cores recovered on elevated plateaus in Lake Baikal: on Continent Ridge, a northern extension of Academician ... [more ▼]

The mineralogical composition of Late Quaternary sediments was investigated in three piston cores recovered on elevated plateaus in Lake Baikal: on Continent Ridge, a northern extension of Academician Ridge in the North Basin; on the Posolsky Bank near the Selenga Delta; and on the Vydrino Shoulder in the South Basin. The sediments are alternating biogenic diatom-rich muds and terrigenous silty clays, with sandy layers occurring in the southern (Vydrino) core. Core stratigraphy is based on AMS C-14 dates on pollen, diatom zonation, and magnetic record correlation: the 6-10 m long cores cover the last similar to 40 kyr in Vydrino, similar to 60 kyr in Posolsky and similar to 185 kyr in Continent Ridge. The bulk, clay (< 2 mu m) and sand (63-200 mu m) mineral signatures are compared with the mineralogical assemblages identified in river sediments and rocks sampled in the Selenga watershed and surface sediments collected in the various sub-basins. Spatial variability in the bulk mineral signature mainly reflects the sediment location relative to the lake margin. The complex clay mineral assemblages are more distinctive in terms of source-area. The clay signature of Vydrino core differs from the two other sites, in its high illite content. The Posolsky assemblage is consistent with the Selenga River clay mineral signature. The Continent Ridge clay assemblage is highly variable, reflecting mixing of several sources including a more proximal contribution than the Barguzin or even the Selenga tributaries. The similar homblende-dominated heavy mineral compositions of the Continent Ridge and Posolsky Bank sediments reflect the homogenous granitoid signature of the watersheds of the eastern side of Lake Baikal. In contrast, in the Southern Basin, the sediments from Vydrino Shoulder are mica-dominated, recording local sedimentary and metamorphic detritus supplies by numerous small rivers. Besides the control of sediment supply by the Selenga River, our data emphasize the significant influences of the Lake Baikal coastal margins in South and North Basin. (c) 2006 Elsevier B.V. All rights reserved. [less ▲]

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See detailMineralogical, Physicochemical Properties of smectite clays from Bana (Western Cameroon) and Preliminary test as Potential oil bleaching earth
Mache, Jacques Richard; Signing, P.; Mbey, J.A. et al

in Applied Clay Science (2014)

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See detailMinéralogie de l’ancienne mine de plomb de La Roche-en-Ardenne (Belgique).
Blondieau, Michel; Hatert, Frédéric ULg

in Le règne minéral (2009), 88

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See detailMinéralogie de la carrière de Beez, Province de Namur, Belgique.
Blondieau, Michel; Hatert, Frédéric ULg; Defoy, Michel

in Règne minéral (Le) (2012), 104

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See detailMinéralogie et palynologie de croûtes et encroûtements calcaires de la steppe algérienne
Tsaki, H.; Mathieu, L.; Marcoen, Jean Marie ULg et al

in Biocénoses (1988), 3(1-2), 108-118

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See detailMinéralogie et pétrographie des phosphates de pegmatites brésiliennes, avec un intérêt particulier pour leurs relations avec les silicates
Baijot, Maxime ULg; Hatert, Frédéric ULg; Philippo, Simon

in Abstract book, 26ème Réunion annuelle des collaborateurs scientifiques du Musée d'histoire naturelle du Luxembourg (2009)

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See detailMinéralogie et propriétés physico-chimiques des smectites de Bana et Sabga (Cameroun). Utilisation dans la décoloration d'une huile végétale alimentaire
Mache, Jacques Richard ULg

Doctoral thesis (2013)

In this study, clay samples were collected in the localities of Bana and Sabga, in the regions of the west and north-west Cameroon, respectively. The purpose of this study was to determine their ... [more ▼]

In this study, clay samples were collected in the localities of Bana and Sabga, in the regions of the west and north-west Cameroon, respectively. The purpose of this study was to determine their mineralogical composition, their physico-chemical properties and to assess their potential use in the bleaching process of palm oil, which is the main edible vegetable oil produced and refined in Cameroon. <br /> The results obtained from the analyses (XRD, FTIR, DTA / TGA and SEM) revealed that montmorillonite is the main clay mineral in these materials. It is associated with kaolinite and mica. Non-clay minerals such as quartz, anatase, cristobalite, K-feldspar and heulandite are also identified in variable quantities. Chemical analyses of the major elements show that the clays from Bana and Sabga consist mainly of the follow oxides such as SiO2, Al2O3 and Fe2O3. Bana clays have a cation exchange capacity (CEC) between 50 and 60 meq/100 g and a specific surface area between 50 and 60 m2/ g. Sabga clays have a lower capacity cation exchange (38- 46 meq/100 g) and a wider range of specific surface area (33-90 m2 / g). The characterization of the natural clays allowed to select of one sample by locality for sulfuric acid treatment. <br />The acid treatment of these materials led to structural, morphological and textural changes. Analysis by X-ray diffraction showed a progressive decrease in the intensity of the (001) reflection of montmorillonite and a shift of its basal d001-value. Treatment with more acid concentration causes an increase in the surface area of the obtained products and a decrease in cation exchange capacity. <br />The assessment of the bleaching power of natural and acid-activated Bana clay in palm oil decolorization shows that the activated clay has a high bleaching capacity (~ 87%) compared to the natural clay (~ 55%). palm oil Bleaching by these clay materials does not deteriorate the bleached oil. These materials can thus be used as bleaching earths in the refining oil process. [less ▲]

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See detailMineralogy and crystal chemistry of natural and synthetic uranyl oxysalts
Dal Bo, Fabrice ULg

Doctoral thesis (2016)

Since 1960, the number of described uranyl mineral species has been multiplied by three. To date more than 200 mineral species containing uranium as a main structural element are reported in Nature, and ... [more ▼]

Since 1960, the number of described uranyl mineral species has been multiplied by three. To date more than 200 mineral species containing uranium as a main structural element are reported in Nature, and the crystal structures have been determined and refined for only one third of them. Furthermore, many new uranyl minerals are still reported to data, showing sometimes novel chemical compositions and structural arrangements. The uranium mineralogy is a fascinating subject, and an essential field of research as it contributes to the improvement of the management techniques of nuclear waste. The first part of this work was dedicated to the mineralogical characterisation of uranyl minerals, and especially of the autunite-type minerals, occurring in the Rabejac deposit. Indeed, the identification analyses have shown that many samples contain uranyl arsenates of the autunite and meta-autunite groups. Electron-microprobe chemical analyses performed on these minerals species indicate that the P content in (meta-)zeunerite and (meta-)uranospinite is significant in several samples, confirming the solid-solution series between uranyl arsenates and phosphates. Also, cationic substitutions occurring on the A site were observed, especially in uranospinite samples, in which significant amount of Ca is substituted for Mg. Single-crystal X-ray diffraction experiments have been performed on many members of the (meta-)zeunerite-(meta-)torbernite series, and the crystallographic parameters were put into correlation with the variation of the chemical composition. The crystal structure of arsenuranospathite, the Asanalogue of the Al-bearing uranyl phosphate uranospathite, was solved for the first time, indicating that these two minerals are isostructural (Dal Bo et al., 2015). Also, a structure model is proposed for metauranocircite-I, one of the Ba-bearing uranyl phosphate of the meta-autunite group. Investigations of uranyl mineral samples from other localities have allowed to discover single-crystals of bassetite, one of the Fe end-members of the autunite group. The crystal structure of bassetite was also solved for the first time, and these new structural data were presented in parallel to those obtained on saléeite, the Mg-analogue of bassetite (Dal Bo et al., 2016). Thanks to these new data, a discussion about the mineral hierarchy of the (meta-)autunite group is proposed. In addition, the crystal structure of the rare Al-bearing uranyl phosphate furongite from the Kobokobo pegmatite was determined, showing that this mineral species has unique and novel structural features. This specific study, as well as the redefinition of the structural formula of phuralumite, was the occasion to provide a review about the formation of Al polyhedra clusters in uranyl minerals, and to try to elucidate their physicochemical conditions of crystallisation. Many new crystallographic data were also collected on uranyl minerals for which the crystal structure was already reported in the literature. Therefore, it was possible to confirm the previous studies, or to highlight important discrepancies, especially in the case of the Al-bearing uranyl phosphate phuralumite. The H-bonds networks, which are essential for the stability of the structure, have been established in the structure of the uranyl carbonate liebigite, and in the structure of the uranyl silicates cuprosklodowskite, kasolite and soddyite. The second part of this work was devoted to the hydrothermal synthesis of uranyl oxysalts. The experimental conditions, as well as the chemical systems, were chosen in agreement with the conditions occurring in natural uranium deposits, or in geological repositories. A new compound, Be[(UO2)(PO4)]2(H2O)2.5, has been synthesized at low temperature. This is the third Be-bearing uranyl phosphate reported to date, and its crystal structure is based upon sheets showing the uranophane anion topology, typical of uranyl silicates occurring in the oxidation zone of the uranium deposits. The well-known Ba[(UO2)3(MoO4)4(H2O)](H2O)3 and (NH4)2[(UO2)(MoO4)2](H2O) compounds have been synthesized, and new crystallographic data were collected on them. In addition, it was possible to determine the hydrogen-bonds networks for the first compound, and to redefine the Mo6+ coordination polyhedra in the second one. [less ▲]

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See detailMineralogy and petrography of phosphate minerals from pegmatites of the Conselheiro Pena district, Minas Gerais, Brazil
Baijot, Maxime ULg; Hatert, Frédéric ULg; Philippo, Simon

in Acta Mineralogica-Petrographica, Abstract series (2010), 6

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See detailMineralogy and petrography of phosphate minerals from Sapucaia and Boca Rica pegmatites, Minas Gerais, Brazil
Baijot, Maxime ULg; Hatert, Frédéric ULg; Philippo, Simon et al

in Estudios Geologicos (2009), 19(2), 47-51

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See detailMineralogy and physico-chemical properties of alluvial clays from
Nzeugang Nzeukou; Fagel, Nathalie ULg; Njoya, André et al

in Applied Clay Science (2013), 83-84

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See detailMineralogy and physico-chemical properties of alluvial clays from Sanaga valley (Center, Cameroon): Suitability for ceramic application,
Nzeukou, Aubin; Fagel, Nathalie ULg; Njoya, André et al

in Applied Clay Science (2013), (83-84), 238-243

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See detailMineralogy of fine particles in slurry from multispectral imaging
Leroy, Sophie ULg; Dislaire, Godefroid ULg; Barnabé, Pierre ULg et al

Conference (2014, September 02)

Quantitative mineralogy of fine particles in slurry from multispectral imaging Sophie Leroy, Godefroid Dislaire, Pierre Barnabé and Eric Pirard Mineral processing especially in its final stages relies ... [more ▼]

Quantitative mineralogy of fine particles in slurry from multispectral imaging Sophie Leroy, Godefroid Dislaire, Pierre Barnabé and Eric Pirard Mineral processing especially in its final stages relies heavily on the differential behavior of particles in pulps. In order to monitor hydrocyclones and flotation cells in almost real time, it is important to develop at line particle characterization providing information on particle distribution but also mineralogy. A sampling device has been elaborated based on a flow cell with variable wall spacing linked to a high pressure peristaltic pump. This setup allows for dispersion and dilution of the mineral slurry into the cell. Depending on the ore or gangue minerals to be controlled, particles can be imaged either in diffuse reflectance or in transmittance mode. A simple multispectral imaging module has been designed to acquire images at eight different wavelengths. The design is based on a series of dichroic filters thereby avoiding any moving part and enabling a very fast acquisition of multispectral images. Imaging artifacts due, among others, to specular reflectance from the glass window are minimized. Multispectral classification is used to outline particles appearing in the field of view and to qualify their main mineral component. In particular, areas reflecting a meaningful and discriminative spectrum are identified and compared to a multispectral database. The database is continuously enriched through testing of pure mineral particles under similar pulp conditions (dilution, grain size,…). Results of final classification are compared to the modal analysis obtained from polished blocks and conventional reflected light microscopy. The technology developed in this work sets the basis for at line monitoring of ore slurries with reasonably simple mineralogy. Extension of the spectral range is being considered for future developments. [less ▲]

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