The Experts below are selected from a list of 186 Experts worldwide ranked by ideXlab platform

Désindes Laurent - One of the best experts on this subject based on the ideXlab platform.

  • Genesis of the Dordogne (France) high-purity silica placers
    2006
    Co-Authors: Désindes Laurent, Durand M., Bailly Laurent, Jaillet Stéphane, Bouchot Vincent, Lespinasse Marc, Pouliquen M., Ostermann J.m., Leroy J.
    Abstract:

    International audienceThis article describes the formation of the principal French high-purity silica placer (source for Electrometallurgy of silicon and ferrosilicon), the Boudeau deposit in Dordogne, and of one of its subordinate deposits, the Pays Brûlé deposit. Boudeau has always been considered to be a colluvial deposit, formed in a trap produced by extensional tectonism. The present work suggests a new genetic interpretation, based on a combined study of the deposits and their underlying rocks. It shows that the quartz gravel deposits, laid down by stream flow within braided channels, were reworked by karstic progressive sinking, and that the mechanism responsible for the increase in the thickness of the economic formations is cryptokarstic corrosion. This undercovers weathering process, which involves dissolution of karstifiable rocks (oolitic and bioclastic limestones) at their interface with a permeable, non-karstifiable cover composed of chemically pure quartz gravels in a sandy-argillaceous matrix. A typological study of the gravels provides a basis for tackling the problem of their origin and their purity. They seem to be derived mainly from the synmetamorphic quartz mobilisates of the stripped metamorphic units (the lower and upper gneiss units forming the western edge of the Massif Central). Lastly, a dynamic model is suggested for the genesis of the high-purity silica deposits of Dordogne

  • Silice ultra-pure pour l'électrométallurgie : gîtologie et caractéristiques physiques et chimiques du minerai quartz
    2004
    Co-Authors: Désindes Laurent
    Abstract:

    L'augmentation des besoins en produits de haute technologie est responsable d'une demande croissante en minéraux de spécialité et conditionne très fortement la stratégie des grands groupes industriels. Cependant, la typologie de ces nouveaux minerais et la gîtologie de leurs gisements sont très mal connues. La silice ultra pure pour l'électrométallurgie du silicium offre les meilleures opportunités d'étude. Un projet de thèse a donc été proposé par le BRGM en coopération avec l'Université Henri Poincaré de Nancy, dans le but d'explorer quelques pistes d'importance en ce qui concerne ce minerai et ses gisements. Ce travail a permis de proposer, à partir de l'étude conjointe du gisement et de son substratum, un nouveau modèle génétique original du plus gros placer français, propice à la recherche de nouveaux gisements. En ce qui concerne le minerai quartz, quelques nouvelles données sur la définition de sa qualité et sur les études à mener pour la caractériser ont été avancées.The increasing demand for high technology products will soon result in an increasing need for specialty minerals, which is of major interest for big industrial groups. However, the ore typology and gitology of these specialty minerals have been poorly documented. Consequently, a study of ultra high purity silica deposits (from which silicon is produced in the Electrometallurgy process) has been undertaken as a Ph.D. project originally proposed by the BRGM and the University Henri Poincaré of Nancy. This project aimed at exploring some important aspects of these silica deposits has resulted in a new genetic model for the biggest French placer, which can serve as a basis for the prospection of other high purity silica deposits. With respect to the quartz ore itself, new data have been obtained which make it possible to propose a better definition of its quality, and of the future studies which should be undertaken to characterize this quality

  • Silice ultra-pure pour l'électrométallurgie (gîtologie et caractéristiques physiques et chimiques du minerai quartz)
    2004
    Co-Authors: Désindes Laurent, Leroy Jacques
    Abstract:

    L'augmentation des besoins en produits de haute technologie est responsable d'une demande croissante en minéraux de spécialité et conditionne très fortement la stratégie des grands groupes industriels. Cependant, la typologie de ces nouveaux minerais et la gîtologie de leurs gisements sont très mal connues. La silice ultra pure pour l'électrométallurgie du silicium offre les meilleures opportunités d'étude. Un projet de thèse a donc été proposé par le BRGM en coopération avec l'Université Henri Poincaré de Nancy, dans le but d'explorer quelques pistes d'importance en ce qui concerne ce minerai et ses gisements. Ce travail a permis de proposer, à partir de l'étude conjointe du gisement et de son substratum, un nouveau modèle génétique original du plus gros placer français, propice à la recherche de nouveaux gisements. En ce qui concerne le minerai quartz, quelques nouvelles données sur la définition de sa qualité et sur les études à mener pour la caractériser ont été avancées.The increasing demand for high technology products will soon result in an increasing need for specialty minerals, which is of major interest for big industrial groups. However, the ore typology and gitology of these specialty minerals have been poorly documented. Consequently, a study of ultra high purity silica deposits (from which silicon is produced in the Electrometallurgy process) has been undertaken as a Ph.D. project originally proposed by the BRGM and the University Henri Poincaré of Nancy. This project aimed at exploring some important aspects of these silica deposits has resulted in a new genetic model for the biggest French placer, which can serve as a basis for the prospection of other high purity silica deposits. With respect to the quartz ore itself, new data have been obtained which make it possible to propose a better definition of its quality, and of the future studies which should be undertaken to characterize this quality.NANCY1-SCD Sciences & Techniques (545782101) / SudocSudocFranceF

  • Silice ultra-pure pour l'électrométallurgie : gîtologie et caractéristiques physiques et chimiques du minerai quartz
    2004
    Co-Authors: Désindes Laurent
    Abstract:

    Rapporteur : Professeur Yves Quinif, Faculté Polytechnique de Mons, Belgique Rapporteur : Michel Bonnemaison, Chef d'Unité Roches et Minéraux IndustrielsThe increasing demand for high technology products will soon result in an increasing need for specialty minerals, which is of major interest for big industrial groups. However, the ore typology and gitology of these specialty minerals have been poorly documented. Consequently, a study of ultra high purity silica deposits (from which silicon is produced in the Electrometallurgy process) has been undertaken as a Ph.D. project originally proposed by the Bureau de Recherches Géologiques et Minières (BRGM) and the Université Henri Poincaré (UHP) of Nancy. This project aimed at exploring some important aspects of these silica deposits has resulted in a new genetic model for the biggest French placer, which can serve as a basis for the prospection of other high purity silica deposits. With respect to the quartz ore itself, new data have been obtained which make it possible to propose a better definition of its quality, and of the future studies which should be undertaken to characterize this quality.L'augmentation des besoins en produits de haute technologie est responsable d'une demande croissante en minéraux de spécialité et conditionne très fortement la stratégie des grands groupes industriels. Cependant, la typologie de ces nouveaux minerais et la gîtologie de leurs gisements sont très mal connues. La silice ultra pure pour l'électrométallurgie du silicium, au coeur de cette vaste thématique, offre les meilleures opportunités d'étude. Un projet de thèse a donc été proposé par le Bureau de Recherches Géologiques et Minières (BRGM), en coopération avec l'Université Henri Poincaré (UHP) de Nancy, dans le but d'explorer quelques pistes d'importance en ce qui concerne ce minerai et ses gisements. Ce travail a permis de proposer, à partir de l'étude conjointe du gisement et de son substratum, un nouveau modèle génétique original du plus gros placer français incluant les sources, le transport et le piégeage du minerai, propice à la recherche de nouveaux gisements. En ce qui concerne le minerai quartz, quelques nouvelles données sur la définition de sa qualité et sur les études à mener pour la caractériser ont été avancées

Celia De Fraga Malfatti - One of the best experts on this subject based on the ideXlab platform.

  • recovery of copper from printed circuit boards scraps by mechanical processing and Electrometallurgy
    2006
    Co-Authors: Hugo Marcelo Veit, Jorge Alberto Soares Tenorio, Celia De Fraga Malfatti, Jane Zoppas Ferreira, Andréa Moura Bernardes
    Abstract:

    The constant growth in generation of solid wastes stimulates studies of recycling processes. The electronic scrap is part of this universe of obsolete and/or defective materials that need to be disposed of more appropriately, or then recycled. In this work, printed circuit boards, that are part of electronic scrap and are found in almost all electro-electronic equipments, were studied. Printed circuit boards were collected in obsolete or defective personal computers that are the largest source of this kind of waste. Printed circuit boards are composed of different materials such as polymers, ceramics and metals, which makes the process more difficult. However, the presence of metals, such as copper and precious metals encourage recycling studies. Also the presence of heavy metals, as Pb and Cd turns this scrap into dangerous residues. This demonstrates the need to search for solutions of this kind of residue, in order to have it disposed in a proper way, without harming the environment. At the first stage of this work, mechanical processing was used, as comminution followed by size, magnetic and electrostatic separation. By this process it was possible to obtain a concentrated fraction in metals (mainly Cu, Pb and Sn) and another fraction containing polymers and ceramics. The copper content reached more than 50% in mass in most of the conductive fractions and significant content of Pb and Sn. At the second stage, the fraction concentrated in metals was dissolved with acids and treated in an electrochemical process in order to recover the metals separately, especially copper. The results demonstrate the technical viability of recovering copper using mechanical processing followed by an electrometallurgical technique. The copper content in solution decayed quickly in all the experiments and the copper obtained by electrowinning is above 98% in most of the tests.

Jose Arana Varela - One of the best experts on this subject based on the ideXlab platform.

  • sintering of tin oxide using zinc oxide as a densification aid
    2004
    Co-Authors: C R Foschini, Leining Antonio Perazolli, Jose Arana Varela
    Abstract:

    The physicochemical electronic characteristics of SnO2 render it useful in many technical applications, including ceramic varistors, stable electrodes used in electric glass-melting furnaces and Electrometallurgy of aluminum, transparent windows and chemical sensors. The use of ZnO as a sintering aid was explored in this study to obtain SnO2 as a dense ceramic. Compacts were obtained by mechanical mixing of oxides, isostatic pressing at 210 MPa and sintering in situ inside a dilatometer at heating rates of 10°C/min. The grain size and microstructure were investigated by scanning and transmission electron microscopy (SEM/TEM). The phases and chemical composition were analyzed by energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results indicated that ZnO acts as a densification aid for SnO2, improving its grain growth with additions of up to 2 mol%. ZnO forms a solid solution with SnO2 up to 1 mol%, above which SnZnO3 precipitates in the grain boundary, potentially inhibiting shrinkage and grain growth.

Satinder Kaur Brar - One of the best experts on this subject based on the ideXlab platform.

  • integrated bioleaching Electrometallurgy for copper recovery a critical review
    2021
    Co-Authors: Kamalpreet Kaur Brar, Sara Magdouli, Selma Etteieb, Mehdi Zolfaghari, Homayoun Fathollahzadeh, Laura Calugaru, Simonpierre Komtchou, Rayen Tanabene, Satinder Kaur Brar
    Abstract:

    Abstract The recovery of copper from secondary waste resources (e.g. electronic wastes, slag, fly-ash, sludge and spent catalysts) via oxidative and reductive bioleaching becomes a running trend and a potential alternative to limited metal supply. The motive of this review is to ponder over recycling of secondary waste towards the circular economy to reduce environmental risks as well as to increase the economic profitability of the mining industry. The biochemistry of iron/sulfur minerals, bacteria–mineral interactions and adaptive behavior allowing the acidophiles to survive are among the key parameters to be optimized during the bio recovery of copper. The use of OMICS approaches such as genomics, proteomics, transcriptomics and metabolomics is also crucial to elucidate a comprehensive view of the bioleaching communities, their mechanisms and interactions with minerals. This handy information can act as a boon to develop potential strains by adopting synthetic biology and antiviral CRISPR-Cas9 technologies to efficiently control the bioleaching process. Furthermore, some of these recent discoveries to design bioelectrochemical system (BES) and to achieve higher rate of metal recovery are discussed. Finally, the objective of this study is to narrow the gap between fundamental and applied research to fully address scientific, technological and economic challenges and bottlenecks of bioleaching process in general and BES in particular.

Svetomir Hadži Jordanov - One of the best experts on this subject based on the ideXlab platform.

  • Education Electrometallurgy: ELECTROCHEMICAL, ECONOMIC AND ENVIRONMENTAL (3E) ASPECTS1*
    2010
    Co-Authors: Perica Paunović, Svetomir Hadži Jordanov
    Abstract:

    This paper is concerned with electrolysis processes aimed for production and refining of metals. This engineering field is named Electrometallurgy. The main aspects of Electrometallurgy such as electrochemical, energetic/economic and environmental ones are given. The peculiarity of electrorefining and electrowining in both aqueous electrolytes and molten salts are shown. The impact of energetic parameters, such as cell voltage and current efficiency on the economic justification of the electrolysis process is analyzed. It is emphasized that electrolysis is considerably cleaner technology than the pyrometallurgical production and refining of metals. Key words: Electrometallurgy; electrorefining; electrowining; aqueous electrolytes; molten salts; specific energy consumption. ЕЛЕКТРОМЕТАЛУРГИЈА: ЕЛЕКТРОХЕМИСКИ ЕКОНОМСКИ И ЕКОЛОШКИ (3Е) АСПЕКТ