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The Global ETD Search service is a free service for researchers
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Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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An experimental investigation of intergrowth phenomena in bornite and chalcopyrite.Newham, Walter. D. January 1963 (has links)
No description available.
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A Study of Flotation and Leaching Behaviour of Bornite and ChalocpyriteMosweu, GABOTSWANE 13 January 2014 (has links)
This study was carried out to investigate the flotation and leaching behaviour of bornite and chalcopyrite when they are together as principal sulphide minerals. Bench scale flotation performance was examined both in the absence and in the presence of a collector, PEX. In the absence of a collector, chalcopyrite floated significantly better than bornite. In the presence of a collector there was a reversal in selectivity, with bornite recovery presiding over that of chalcopyrite. Chalcopyrite recovery was marginally improved from the collectorless flotation case while bornite experienced vastly improved recoveries in the presence of a collector to surpass the recovery of chalcopyrite. The gap between floatability of bornite and chalcopyrite became more prominent under oxygen-deficient conditions induced by nitrogen flotation, which significantly decreased flotation rate of both minerals, but the floatability of bornite was still much higher than that of chalcopyrite. It is suggested that galvanic interactions promote the interaction of bornite with a collector while retarding interactions of chalcopyrite with the collector. Collectorless flotation of chalcopyrite observed under oxidizing conditions using air is thought to be prevalent even in the presence of a collector obscuring the selectivity of the process.
Leaching of the mixtures of bornite and chalcopyrite at mass ratios of 1:1, 1:3 and 3:1 are performed under various conditions to investigate the possible changes in leaching behaviour in relation to galvanic interactions. Leaching at 90°C in the presence of 0.1 M ferric ions in 0.1 M sulphuric acid provided the best results with 90% copper extraction from the mixtures in 6 hours. Observed copper extractions suggested increased copper extraction from chalcopyrite with this approach. The introduction of cupric and ferrous ions into solution, together with variation of solution potential made it difficult to assess in details on the effects of galvanic interactions due to these parameters being known to improve copper extraction from chalcopyrite. Galvanic interactions together with the presence of cupric ions were held mainly responsible for the increased copper extraction. / Thesis (Master, Mining Engineering) -- Queen's University, 2014-01-11 00:25:35.365
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Associated Sulfide Minerals in Thiosulfate Leaching of Gold: Problems and SolutionsXia, Chen 01 April 2010 (has links)
The effects of some associated minerals on thiosulfate gold leaching were studied through thermodynamic analysis and leaching experiments on composite ore samples containing various minerals and a reference silicate gold ore.
In the leaching test on the reference gold ore, about 93% of gold was extracted within 3.0 hours. The presence of various amount of pyrite, pyrrhotite, chalcopyrite, arsenopyrite, chalcocite, bornite, and some lead species, has significant detrimental effects.
Under reduced oxygen conditions, the thiosulfate consumptions could be significantly reduced. High gold extractions (i.e. >= 90%) were observed in the leaching tests with reduced dissolved oxygen (i.e., 0.7% oxygen in the supplied gas) in the absence or in the presence of sulfide minerals such as pyrite, pyrrhotite, arsenopyrite and chalcopyrite. High copper concentration and a pre-aeration step was also found to largely increase the gold extractions under such conditions.
Thiosulfate-copper-ethylenediamine system was found effective in the leaching of gold. The leaching kinetics was significantly slower than that of the conventional thiosulfate-copper-ammonia leaching. The consumption of thiosulfate, however, was largely reduced. This leaching system worked effectively on the reference gold ore within a wider pH range (e.g., 6-11), with or without ammonia. The presence of ammonia in a low concentration improved the leaching rate but also increase the consumption of thiosulfate. Comparable gold extractions were observed in the leaching of the composite ores containing various sulfide minerals, such as pyrite, pyrrhotite, chalcocite, galena and chalcopyrite.
The leaching of gold in the presence of iron sulfides was also improved by applying chemical additives, such as, carbonate, calcium, galena, phosphate, and additional hydroxide anion. It is proposed that these additives either passivated the harmful surface of sulfide minerals or masked some detrimental aqueous species.
Finally, some improved leaching methods concluded in this study were applied on a few industrial ore samples in order to demonstrate the effectiveness of these methods. It was found that by comprehensively applying these improved thiosulfate leaching strategies, satisfactory gold extractions and thiosulfate consumption results were archived on these ores. / Thesis (Ph.D, Mining Engineering) -- Queen's University, 2008-09-18 11:48:38.672
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Un exemple de minéralisation associée aux ophiolites mésozoïques des Alpes cottiennes. Le gîte de Saint Véran ( Hautes-Alpes, France). Etude pétrographique, structurale et métallogénique.Ayoub, Claude 28 November 1984 (has links) (PDF)
La minéralisation cuprifère de Saint-Véran (Hautes-Alpes, France) est située dans la zone piémontaise. Elle consiste en un horizon sulfuré à bornite. digénite, chalcocite et blende, associée à un niveau de silicates sodiques. Ces matériaux se localisent à l'interface du substratum océanique et des métasédiments. L'assise ophiolitique est une ophicalcite particulière très hématisée. Les métasédiments subjacents sont des métaradiolarites présentant ici un faciès très siliceux. Ils composent la base de la série stratigraphique de la mine , analogue à la série de Chabrière. L'ensemble est affecté de 3 phases plicatives synschisteuses et dessine une synforme d'axe N-S. La présence d'aegyrine et de riébeckite dans le minerai et en niveaux condensés, serait l'expression d' un hydrotnermalisme océanique particulier ; en effet, la localisation de radiolaires en enduits dans les fissures de I'horizon sodique, indique la diagenèse précoce de ces matériaux et leur emplacement proche ou situé sur le fond marin. Les ensembles éruptifs tholéiitiques voisins suggèrent l'emplacement de la minéralisation dans un contexte distensif, à proximité d'une ride océanique active.
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La lithosphère océanique de la Téthys ligure : etude du magmatisme et des minéralisations associées dans les ophiolites du Queyras ( zone piémontaise des Alpes occidentales)Saby, Patrick 09 December 1986 (has links) (PDF)
Les unités ophiolitiques du Queyras (zone Alpes occidentales) représentent des petits massifs de roche vertes dispersées dans les Schistes lustrés piémontais à l'Ouest du Mont Viso. Leur étude permet de reconstruire la structure du substratum d'une partie du segment ligure de la Téthys. Bien que de nombreuses observations de terrain conduisent à envisager une coupure majeure entre la mise en place des ultramafites et gabbros associés et l'épanchement des basaltes, l' analyse pétrographique et géochimique permet de conclure à un assemblage cohérent et comparable avec d'autres massifs ophiolitiques de l' Apennin et de la Corse. Les résultats obtenus soulignent le caractère tholéïtique de la lignée magmatique à l'origine des matériaux basiques, intermédiaires et acides des différentes unités. La typologie des zircons conforte cette hypothèse au niveau des roches acides. La répartition des éléments inertes, Y, Ti, Zr, Nb, montre les liens cogénétiques entre les matériaux basiques et les différenciats acides. La nature du fractionnement ainsi que l'estimation du degré de fusion partielle suggèrent une mise en place dans un environnement géotectonique à caractère transitionnel avec océanisation à proximité de marges continentales passives, ainsi qu'un magmatisme analogues à ceux à l'origine des ophiolites de la Méditerranée occidentale (magmatisme de type I). Les éléments de granitoïdes d'une brèche sédimentaire localisée à l' interface ultramafites-laves, se caractérisent par un cachet calcoalcalin et permettent d'envisager la proximité d'une croûte continentale dont le démantèlement a vraisemblablement été contemporain des stades précoces de l'ouverture de l'océan ligure. Les circulations hydrothermales liées à ce contexte océanique sont responsables des processus de spilitisation et des minéralisations localisées à l'interface substratum océanique / sédiments: le gîte Fe/Cu de Viafiorcia (Val Germanasca, Italie) en est un exemple.
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Geology of the Palo Verde Ranch Area, Owl Head Mining District, Pinal County, ArizonaApplebaum, Steven January 1975 (has links)
A quartz diorite intrusion of probable early Tertiary age that crops out over at least 6 square miles in the Palo Verde Ranch area in Pinal County, Arizona was mapped as a distinct intrusion. The quartz diorite intrudes an area comprising Pinal Schist, Oracle granite, andesitic flows, granoaplite, and dike rocks including both pegmatite and diabase. Two major physical features, the Owl Head Buttes and Chief Buttes volcanic areas, both remnants of an extensive early Tertiary series of flows of intermediate composition that covered the area, now remain as lava-capped buttes above the pediment. Weak but persistent fracture-controlled copper mineralization is found in the quartz diorite and the Pinal Schist at or near their mutual contacts in the form of chrysocolla, malachite, black copper oxides, chalcocite, chalcopyrite, and bornite, in decreasing order. Pyrite is rare. Alteration related to northeast and northwest-trending fractures increases in intensity from the common propylitic to argillic to the northeast toward the San Juan claims area. A barely discernible increase in copper sulfides mirrors the alteration zoning, although geochemical sampling showed background copper in the quartz diorite to be more uniform away from fractures.
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