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Littérature scientifique sur le sujet « Pentlandit »

Auteur : Grafiati

Publié le 4 juin 2021

Mis à jour le 1 février 2022

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Articles de revues sur le sujet "Pentlandit"

Tilley, Janette. « Representations of Gender in Barbara Pentland's Disasters of the Sun ». Canadian University Music Review 22, n^o 2 (4 mars 2013) : 77–92. http://dx.doi.org/10.7202/1014507ar.

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Barbara Pentland (1912–2000) will be remembered as a leading figure in Canadian music, but she regarded her success as hard won. She viewed her career as a struggle against sexual discrimination, and though an advocate of equal rights and social justice, Pentland nevertheless disliked discussing notions of gender and her vocation, claiming it drew attention away from her compositions: she was a composer first and a woman second. Her reticence has a single exception in her 1976 song cycle Disasters of the Sun. As her only work to explore explicitly gender relations, Disasters provides a step towards gaining greater insight into Pentland's attitudes toward gender difference and identity.

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Grguric, B. A. « Hypogene violarite of exsolution origin from Mount Keith, Western Australia : field evidence for a stable pentlandite–violarite tie line ». Mineralogical Magazine 66, n^o 2 (avril 2002) : 313–26. http://dx.doi.org/10.1180/0026461026620032.

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AbstractIn most documented occurrences, violarite (FeNi2S4) occurs as a product of the supergene alteration of primary pentlandite or millerite. Earlier experimental phase relations studies predicted the possible existence of a stable violarite–pentlandite tie line, though there has been little field evidence supporting this hypothesis, and the preferred topology in the Ni-Fe-S system involves a pyrite–millerite tie line. This paper documents the occurrence of violarite-pentlandite±pyrite assemblages which, on the basis of mineral chemistry and textural evidence, appear to be hypogene. Primary cobaltian violarite (with 2.1–13.2 wt.% Co) occurs as lamellae in pentlandite in the MKD5 nickel sulphide orebody at Mount Keith, central Western Australia. These lamellae are interpreted to be of exsolution origin. Cobalt is preferentially partitioned into violarite, resulting in high Ni:Co ratios in the associated pentlandite relative to pentlandite in violarite-free assemblages. Hypogene violarite-millerite±pentlandite assemblages were also noted. In all hypogene assemblages, violarite differs in both textural and mineral chemical characteristics from supergene violarite from the upper portions of the MKD5 orebody. The implications of the assemblages for the known low-temperature phase relations in the Ni-Fe-S-(Co) system are discussed.

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Silva, Bruno Venancio da, Filipe Goulart Lima, Rafael Rodrigues Assis, Antenor Zanardo et Daniel Françoso de Godoy. « Contribuição dos processos magmáticos e tectono-metamórficos na gênese dos minérios sulfetados de Ni-Cu de Mangabal I e Mangabal II, Goiás, Brasil ». Geologia USP. Série Científica 20, n^o 2 (16 avril 2020) : 61–80. http://dx.doi.org/10.11606/issn.2316-9095.v20-142137.

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Os complexos estratiformes Mangabal I e Mangabal II fazem parte de um conjunto de intrusões máfico-ultramáficas sinorogênicas, brasilianas, que ocorrem na região central do Brasil. Neste trabalho, são apresentados novos dados petrográficos e de microscopia eletrônica de varredura dos sulfetos de Ni-Cu de ambos os complexos. Em um litotipo com textura cumulática preservada, ocorrem as associações pirrotita-pentlandita e pirrotita-pentlandita-calcopirita na forma de glóbulos de sulfetos intercumulus. A pirrotita apresenta conteúdos de ferro entre 64,9 e 65,5%, a pentlandita apresenta conteúdos de níquel entre 14,6 e 25,3% e a calcopirita apresenta conteúdos de cobre entre 29,1 e 31,5%. Nos litotipos intensamente transformados pelo metamorfismo e que não preservam textura ígnea, ocorrem as associações pirrotita-pentlandita, pirrotita-pentlandita-calcopirita e pirrotita-pentlandita-calcopirita-pirita, todas associadas a concentrações variadas de rutilo. Essas associações apresentam pirrotita com conteúdos de ferro entre 59,1 e 62,1%, pentlandita com conteúdos de níquel entre 15 e 40% e calcopirita com conteúdos de cobre entre 32,9 e 36,6%. A associação pentlandita-pirita, bem como vênulas compostas de pirita ou calcopirita, constituem fases de substituição e remobilização dos sulfetos preexistentes. Baseando-se na mineralogia, na textura e nos conteúdos de metais base, observa-se que as associações de sulfetos encontradas nos litotipos intensamente transformados pelo metamorfismo são semelhantes em ambos os complexos e diferem das associações encontradas no litotipo que preserva textura ígnea. Dessa forma, sugere-se que os processos tectono-metamórficos atribuídos ao Ciclo Brasiliano ocasionaram remobilizações e mudanças químicas nos sulfetos de Ni-Cu dos complexos Mangabal I e Mangabal II.

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Barnes, Stephen J., Valentina Taranovic, Louise E. Schoneveld, Eduardo T. Mansur, Margaux Le Vaillant, Sarah Dare, Sebastian Staude, Noreen J. Evans et Daryl Blanks. « The Occurrence and Origin of Pentlandite-Chalcopyrite-Pyrrhotite Loop Textures in Magmatic Ni-Cu Sulfide Ores ». Economic Geology 115, n^o 8 (24 août 2020) : 1777–98. http://dx.doi.org/10.5382/econgeo.4757.

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Abstract Pentlandite is the dominant Ni-hosting ore mineral in most magmatic sulfide deposits and has conventionally been interpreted as being entirely generated by solid-state exsolution from the high-temperature monosulfide solid solution (MSS) (Fe,Ni)1–xS. This process gives rise to the development of loops of pentlandite surrounding pyrrhotite grains. Recently it has been recognized that not all pentlandite forms by exsolution. Some may form as the result of peritectic reaction between early formed MSS and residual Ni-Cu–rich sulfide liquid during differentiation of the sulfide melt, such that at least some loop textures may be genuinely magmatic in origin. Testing this hypothesis involved microbeam X-ray fluorescence mapping to image pentlandite-pyrrhotite-chalcopyrite intergrowths from a range of different deposits. These deposits exemplify slowly cooled magmatic environments (Nova, Western Australia; Sudbury, Canada), globular ores from shallow-level intrusions (Norilsk, Siberia), extrusive komatiite-hosted ores from low and high metamorphic-grade terranes, and a number of other deposits. Our approach was complemented by laser ablation-inductively coupled plasma-mass spectrometry analysis of palladium in varying textural types of pentlandite within these deposits. Pentlandite forming coarse granular aggregates, together with loop-textured pentlandite where chalcopyrite also forms part of the loop framework, consistently has the highest Pd content compared with pentlandite clearly exsolved as lamellae from MSS or pyrrhotite. This is consistent with much of granular and loop pentlandite being formed by peritectic reaction between Pd-rich residual sulfide liquid and early crystallized MSS, rather than forming entirely by subsolidus grain boundary exsolution from MSS, as has hitherto been assumed. The wide range of Pd contents in pentlandite in individual samples reflects a continuum of processes between peritectic reaction and grain boundary exsolution. Textures in metamorphically recrystallized ores are distinctly different from loop-textured ores, implying that loop textures cannot be regenerated (except in special circumstances) by metamorphic recrystallization of original magmatic-textured ores. The presence of loop textures can therefore be taken as evidence of a lack of penetrative deformation and remobilization at submagmatic temperatures, a conclusion of particular significance to the interpretation of the Nova deposit as having formed synchronously with the peak of regional deformation at temperatures within the sulfide melting range.

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Chaumba, Jeff B., et Caston T. Musa. « Formation of the main sulfide zone at Unki Mine, Shurugwi Subchamber of the Great Dyke, Zimbabwe : Constraints from petrography and sulfide compositions ». Geosphere 16, n^o 2 (16 janvier 2020) : 685–710. http://dx.doi.org/10.1130/ges02150.1.

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Abstract The major platinum group element (PGE) occurrence in the Great Dyke of Zimbabwe, the main sulfide zone, is a tabular stratabound layer hosted in pyroxenites, and it is broadly similar in form throughout the length of the Great Dyke. We conducted a petrographic and sulfide composition study on a sulfide-enriched zone from the contact of the mafic sequence–ultramafic sequence through the main sulfide zone at Unki Mine in the Shurugwi Subchamber to its underlying footwall rocks to place some constraints on the origin of the rocks. Pyrrhotite, pentlandite, chalcopyrite, and pyrite are the base metal sulfides that were encountered during the study. Pyrrhotite, pentlandite, and chalcopyrite typically occurred as inclusions in both primary (orthopyroxene, plagioclase, and clinopyroxene) and secondary (amphibole and chlorite) silicate phases, whereas pyrite was observed in only three samples, where it occurred in association with pyrrhotite. The concentrations of PGEs in the base metal sulfides were nearly all at or below minimum detection limits. The intercumulus nature of some of these sulfides in the investigated sequence suggests that they were likely formed during the crystallization history of these rocks. The occurrence of pyrite, which we interpret to be an alteration phase, suggests that a late-stage event, likely formed during hydrothermal alteration, helped to concentrate the mineralization at Unki Mine. In some cases, however, these sulfides occur partially surrounding some chromite and silicate phases. Thus, some sulfides in the Unki Mine area were likely formed early in the crystallization history of the Great Dyke, whereas others were formed late during hydrothermal processes. Low concentrations of PGEs such as platinum (Pt), palladium (Pd), and rhodium (Rh) in base metal sulfides imply that the PGEs in the main sulfide zone and Unki Mine are hosted either in silicates and/or platinum group minerals. Very low Co contents in pentlandites in the rocks under investigation are interpreted to imply that very limited Fe substitution by Co, and also of Ni by Co, occurred. Broadly comparable trends, with minor variations of Fe in pyrrhotite, of Co and Ni in pentlandite, and of Cu in chalcopyrite, for example, likely reflect magmatic processes. The concentrations of these metals in base metal sulfides vary sympathetically, indicating that their original magmatic signatures were subsequently affected by hydrothermal fluids. The spiked pattern displayed by the variations in the percent modal proportions of the base metal sulfides across the entire investigated stratigraphic section is interpreted to reflect remobilization of the sulfides during hydrothermal alteration. Depletions in some elements, which occur near the base and at the top of the investigated succession, are likely a result of this hydrothermal alteration.

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Sun, Jianzhi, Jiankang Wen, Biao Wu et Bowei Chen. « Mechanism for the Bio-Oxidation and Decomposition of Pentlandite : Implication for Nickel Bioleaching at Elevated pH ». Minerals 10, n^o 3 (23 mars 2020) : 289. http://dx.doi.org/10.3390/min10030289.

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This work investigated the effects of Fe3+, H+ and adsorbed leaching bacteria on the bioleaching of pentlandite. Collectively, an integrated model for the oxidation and decomposition of pentlandite was built to describe the behaviors of different components in a bioleaching system. Proton ions and ferric ions could promote the break and oxidation of Ni-S and Fe-S bonds. The iron-oxidizing microorganisms could regenerate ferric ions and maintain a high Eh value. The sulfur-oxidizing microorganisms showed significant importance in the oxidation of polysulfide and elemental sulfur. The atoms in pentlandite show different modification pathways during the bioleaching process: iron transformed through a (Ni,Fe)9S8 → Fe2+ → Fe3+ → KFe3(SO4)2(OH)6 pathway; nickel experienced a transformation of (Ni,Fe)9S8 → NiS → Ni2+; sulfur modified through the pathway of S2−/S22− → Sn2− → S0 → SO32− → SO42−. During bioleaching, a sulfur-rich layer and jarosite layer formed on the mineral surface, and the rise of pH value accelerated the process. However, no evidence for the inhibition of the layers was shown in the bioleaching of pentlandite at pH 3.00. This study provides a novel method for the extraction of nickel from pentlandite by bioleaching at elevated pH values.

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Tanabe, Teruo, Ken’ichi Kawaguchi, Zenjiro Asaki et Yoshio Kondo. « Oxidation Kinetics of Pentlandite ». Journal of the Japan Institute of Metals 50, n^o 8 (1986) : 720–26. http://dx.doi.org/10.2320/jinstmet1952.50.8_720.

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Tzamos, E., A. Filippidis, K. Michailidis, A. Koroneos, A. Rassios, G. Grieco, M. Pedrotti et K. Stamoulis. « MINERAL CHEMISTRY AND FORMATION OF AWARUITE AND HEAZLEWOODITE IN THE XEROLIVADO CHROME MINE, VOURINOS, GREECE ». Bulletin of the Geological Society of Greece 50, n^o 4 (28 juillet 2017) : 2047. http://dx.doi.org/10.12681/bgsg.11951.

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The Serpentinite between the chromite bodies 4 and 5 of Xerolivado mine (Vourinos, Greece), contains sparsely very small grains (<20μm) of awaruite (Fe0.91Cu0.06Co0.03Ni3), heazlewoodite (Ni2.91Fe0.06S2), magnetite and Co pentlandite (Ni3.79Fe2.98Co2.38S8). The olivine contains 0.40 wt% NiO and 6.91 wt% FeO, while the serpentine 0.18 wt% NiO and 3.02 wt% FeO. The Co-content of awaruite is 1.31 wt% and that of heazlewoodite 0.12 wt%. Heazlewoodite is a product of the primary Co-pentlandite reduction, resulting from the serpentinization of the ultramafic rock. The Ni content of awaruite is derived both from olivine and from Co-pentlandite. The reducing environment resulting from serpentinization and the low sulphur fugacity, favour the formation of awaruite, heazlewoodite and magnetite.

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Ertseva, L. N., V. T. D’yachenko et L. Sh Tsemekhman. « Interaction of pentlandite, chalcopyrite, and pyrrhotine with elementary sulfur : I. Sulfidizing of pentlandite ». Russian Metallurgy (Metally) 2009, n^o 4 (août 2009) : 289–96. http://dx.doi.org/10.1134/s003602950904003x.

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Tanabe, Teruo, Ken’ichi Kawaguchi, Zenjiro Asaki et Yoshio Kondo. « Oxidation Kinetics of Dense Pentlandite ». Transactions of the Japan Institute of Metals 28, n^o 12 (1987) : 977–85. http://dx.doi.org/10.2320/matertrans1960.28.977.

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Thèses sur le sujet "Pentlandit"

Abrahamsson, Filip. « Leaching of Pyrrhotite from Nickel Concentrate ». Thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-64934.

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Non-oxidative acid leaching of pyrrhotite from Kevitsa’s Ni-concentrate and methods to recover by-products, have been investigated. Selective dissolution of pyrrhotite (Fe1-xS, 0<x<0.25) can enrich the content of the valuable metals, such as Ni and Co, in the final concentrate and will reduce the amount of Fe and S sent to the smelters. The pyrometallurgical smelting of leached concentrate will thus give less formation of smelter by-products in form of slag and SO2. The leaching was studied through an experimental design plan with parameter settings of 38.8% to 57.8% H2SO4 and temperatures from 60 to 100°C. The best results were obtained in experiments carried out at the lower experimental range. Leaching at 60°C with an initial acid concentration of 38.8% H2SO4 was found sufficient to selectively dissolve most of the pyrrhotite; leaving an enriched solid residue. A QEMSCAN analysis of the solid residue confirmed that most of the pyrrhotite had been dissolved and showed that pentlandite was still the main Ni-mineral. Chemical assays showed that more than 95% of the Ni, Co, and Cu remained in the final residue. The utilized leaching process generates by-products, in the form of large quantities of Fe2+ in solution and gaseous H2S. To recover Fe2+, crystallization of iron(ii) sulfate (FeSO4∙nH2O) from leach solution through cooling have been studied. The crystallized crystals were further dehydrated into the monohydrate (FeSO4∙H2O) through a strong sulfuric acid treatment (80%H2SO4). XRD analysis confirmed that FeSO4∙H2O was the main phase in the final crystals, and a chemical analysis showed a Fe content of about 30%, 1.5% Mg, 0.4% Ca, and 0.2% Ni. The possibility to leach the concentrate by circulating the acidic solution from the crystallization stage has been tested. The recirculation of the solution showed no negative effects, as the recoveries of elements and chemical assays of the final solid residue were found to be similar to the obtained assay when the concentrate was leached in a fresh solution.
Icke-oxidativ syralakning av magnetkis från Kevitsas Ni-koncentrat har studerats samt metoder för tillvaratagande av biprodukter. Genom en selektiv upplösning av magnetkis (Fe1-xS, 0<x<0.25) kan värdefulla metaller som Ni och Co anrikas i det slutliga koncentratet. Samtidigt som mängden Fe och S som skickas till smältverken minskar, vilket också innebär att mindre biprodukter i form av slagg och SO2 erhålls vid den pyrometallurgiska smältningen av Ni-koncentratet. En experimentell design plan genomfördes för att studera lakningen där syrakoncentrationen varierades från 38.8% till 57.8%H2SO4 och temperatur från 60 till 100°C. Bäst resultat erhölls vid de lägre parameterinställningarna. Lakning vid 60°C med en initial syrakoncentration på 38.8%H2SO4 visade sig vara tillräcklig för att selektivt lösa upp merparten av all magnetkis och lämna kvar en anrikad produkt. Via QUEMSCAN bekräftades att merparten av all magnetkis hade löst upp sig och att huvudsakligt Ni-mineral fortfarande var pentlandit. Kemiska analyser visade att mer än 95% av Ni, Co och Cu stannade kvar i fasta godset. Den tillämpade lakningsmetoden genererar biprodukter i form av stora mängder Fe2+ i lösning och H2S i gasform. För att tillvarata Fe2+ har kristallisering av laklösning som järn(ii) sulfat (FeSO4∙nH2O) studerats genom kylning. De kristalliserade kristallerna avvattnades till monohydrat, FeSO∙1H2O, genom avvattning i stark svavelsyra (80%H2SO4). XRD bekräftade FeSO∙1H2O som huvudfas i slutliga kristallerna och kemisk analys visade på ca 30%Fe med huvudsakliga orenheter i form av 1.5% Mg, 0.4%Ca och 0.2% Ni. Möjligheten till att laka i återcirkulerad lösning efter kristallisering har undersökts. Lakning i återcirkulerad lösning visade inga negativa effekter då liknande halter och utbyten erhölls till det fasta godset.

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Smit, Danie Strydom. « The leaching behaviour of a Ni-Cu-Co sulphide ore in an oxidative pressure-acid medium / Danie Strydom Smit ». Thesis, Potchefstroom University for Christian Higher Education, 2001. http://hdl.handle.net/10394/9626.

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Hydrometallurgical processing of sulphide concentrates is an attractive method for the selective extraction of valuable metals. The dissolution of minerals in a leaching process involves several electrochemical parameters that need to be investigated• to ensure the development and growth of the base metal industry in South Africa. A study has been carried out to elucidate the leaching mechanism of a nickel-coppercobalt sulphide concentrate in an oxidative pressure-acid medium. The sulphide concentrate studied in this research, comprises mainly of the minerals pyrrhotite, (Fe1_xS) with x = 0 to 0.2, pentlandite, (Ni,Fe)9S8 and chalcopyrite, (CuFeS2). The leaching behaviour of these minerals was successfully studied by means of Atomic Absorption (AA) measurements, Scanning '•Electron Microscopy (SEM) and Moss bauer spectroscopy, after leaching took place in an oxidative pressure-acid medium. The dissolution of the valuable metals was achieved effectively with recoveries of well over 90% for nickel, copper and cobalt under the specific conditions studied. Mechanical activation by means of ultra fine milling improved metal extraction with an average of approximately 40%, after a leaching period of 150 minutes. The most suitable conditions for the oxidative pressure-acid leaching of the mechanically treated nickel-copper-cobalt sulphide concentrate in a dilute sulphuric acid medium were found to be: particle size 80% - 10J.Lm; temperature l10°C; oxygen partial pressure 10 bar; sulphuric acid concentration 30 kg/ton; solids content 15% by mass and an impeller agitation rate of 800 r/min. The values of the apparent activation energies of nickel, copper and cobalt, extracted from the sulphide concentrate, were found to be 20.6 (± 4.4) kJ/mol K, 33.6 (± 4.2) kJ/mol K and 17.4 (± 3.5) kJ/mol K respectively.
Thesis (MIng (Chemical Engineering))--Potchefstroom University for Christian Higher Education, 2001

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Malysiak, Vratislav. « Pentlandite-pyroxene and pentlandite-feldspar interactions and their effect on separation by flotation ». Doctoral thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/5291.

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Bibliography: leaves 139-146.
The present study has focused on exploring the extent to which metal ion activation occurs and influences flotation and how this can be managed so as to increase the separation of pentlandite from pyroxene and feldspar. The aim was to minimise the percentage pyroxene and feldspar reporting to the concentrate and simultaneously maximise the pentlandite recovery. The possible chemical reactions taking place on surfaces of synthetic pentlandite, natural pyroxene and feldspar were investigated at pH 4, 6 and 9 in di-sodium tetra borate solution and in synthetic process water in the case of zeta potential determinations, microflotation and ToF-SIMS (time of flight secondary ion mass spectrometry) analyses and in synthetic process water in the case of batch flotation tests.

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Kelly, David P. « Pentlandite exsolution in the Fe-Ni-S system : a mechanistic approach to pentlandite/pyrrhotite ore textures ». Thesis, Aston University, 1985. http://publications.aston.ac.uk/14368/.

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Bozkurt, Volkan. « Pentlandite/pyrrhotite interactions and xanthate adsorption ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/NQ44368.pdf.

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Alvarez, Silva Mayeli. « Surface chemistry study on the pentlandite- serpentine system ». Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97112.

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Interaction with MgO-minerals is one mechanism suspected to reduce selectivity in flotation of pentlandite from ultramafic ore. Understanding the surface chemistry of the minerals involved will lead to improved flotation conditions that maximize flotation selectivity. The first part of the thesis compares isoelectric point (i.e.p.) and point of zero charge (p.z.c.) determined using Mular-Roberts [M-R] titration technique of MgO-minerals chlorite, serpentine and talc. The M-R technique was unsuccessful with talc, attributed to Mg2+ acting as potential determining ion. For serpentine and chlorite, respectively, p.z.c. was pH 4.3 and 4.6 and i.e.p. pH 3.2 and <3. Dispersion index (DI) for chlorite suggested that aggregation/dispersion is controlled by both; serpentine remained dispersed, possibly due to hydration effects.The second part determines surface properties of pentlandite and serpentine isolated from an ultramafic ore. Zeta potential measurements were made on minerals alone and as mixtures with either indifferent electrolyte or supernatant derived from an ore suspension as background. Individual mineral results anticipated interaction due to electrostatic attraction. This was confirmed in the mixed mineral case, with Mg(OH)2 precipitate interaction as an additional factor. Scanning electron microscopy validated the findings.Aggregation/dispersion was determined by turbidimetry using a light scattering technique and optical microscopy. The effect of selected factors on aggregation/dispersion of pentlandite and serpentine was investigated by a design of experiment (DOE). Concentration of carboxymethyl cellulose, CMC, and the interaction between CMC and pH were the important factors. Contact angle measurements explored effects of several factors on pentlandite hydrophobicity and, using a DOE, small-scale flotation was used to investigate effects on pentlandite floatability. The pH was the most important factor, acidic pH increasing both hydrophobicity and floatability. Copper activation enhanced both properties, as well; magnesium affected hydrophobicity at alkaline pH, but it did not show significant effect on floatability; serpentine was detrimental to the process; and CMC was capable of partially restoring the hydrophobicity and floatability of pentlandite depressed with serpentine.
L'interaction de la pentlandite avec des minéraux d'oxide de magnésium (MgO-) est soupçonnée d'être à l'origine de la sélectivité réduite de la pentlandite dans les procédés de flottation de minerais ultrabasiques. Une meilleure compréhension de la chimie de surface des minéraux impliqués devrait mener à l'amélioration des conditions de flottation qui en maximisent la sélectivité. La première partie de la thèse compare le point isoélectrique (p.i.e) et le point de charge nulle (p.c.n), déterminés à l'aide de la technique de titrage Mular-Roberts [M-R], de minéraux d'oxide de magnésium tels que la chlorite, la serpentine et le talc. Dans le cas du talc, la technique M-R a échoué, probablement dû aux ions Mg2+ qui jouent le rôle d'ions déterminateurs de potentiel. Dans le cas de la serpentine et de la chlorite, les p.c.n. ont été déterminés à pH 4,3 et 4,6 respectivement et les p.i.e à pH 3,2 et <3 respectivement. Des tests de décantations ont suggéré que l'agrégation/dispersion observée pour la chlorite était contrôlée à la fois par le p.c.n et le p.i.e ; la serpentine au contraire est restée dispersée, possiblement dû à des effets d'hydratation. La deuxième partie détermine les propriétés de surface de la pentlandite et de la serpentine isolées à partir d'un minerai ultrabasique. Des mesures du potentiel zêta ont été effectuées sur les minéraux seuls et mélangés en présence d'un électrolyte, indifférent dans un cas et surnageant dans l'autre cas, préparé à partir d'une suspension de minerai utilisée comme milieu d'étude. Les résultats relatifs aux minéraux individuels et en particulier les forces d'attraction électrostatique observables ont permis d'anticiper leur interaction. Cette hypothèse a été confirmée dans le cas des minéraux mélangés, étant après avoir pris en compte l'interaction de précipités de Mg(OH)2 comme facteur additionnel. Des observations au microscope électronique à balayage ont permis de valider les résultats. L'agrégation/dispersion a été déterminée par décantation en utilisant des techniques de lumière diffuse et de microscopie optique. L'effet de certains facteurs sur l'agrégation/dispersion de la pentlandite et de la serpentine a été étudié sur la base d'un plan d'expériences (PE). Entre autres, la concentration en carboxymethyl cellulose (CMC) et l'interaction entre le CMC et le pH ont été considérés comme des facteurs importants. Des mesures d'angle de contact ont permis d'explorer l'hydrophobicité de la pentlandite et, à l'aide d'un PE, une étude de flottation à petite échelle a été réalisée pour investiguer la flottabilité de la pentlandite. Les résultats ont montrés que le pH était le facteur le plus important, un pH acide ayant pour effet d'augmenter à la fois l'hydrophobicité et la flottabilité. L'ajout de cuivre a également permis de renforcer ces deux propriétés par un effet d'activation; la présence de magnésium au contraire a affecté l'hydrophobicité de la pentlandite à pH alcalin mais n'a pas eu d'effet significatif sur ses propriétés de flottabilité; la présence de serpentine s'est trouvée être préjudiciable au procédé mais l'utilisation de CMC a pu être utilisée afin de restaurer partiellement l'hydrophobicité et la flottabilité de la pentlandite diminuées par la présence de la serpentine.

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Page, Paul William. « Electrochemical behaviour of pyrite, pyrrhotite, pentlandite and chalcopyrite ». Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47605.

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Mehlape, Mofuti Amos. « Computational modeling studies of cobalt pentlandite (Co₉S₈) ». Thesis, University of Limpopo (Turfloop Campus), 2013. http://hdl.handle.net/10386/984.

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Thesis (Ph.D. (Physics)) --University of Limpopo, 2013
The intention of the current study is to investigate structure, ion transport and reactivity of various forms of the cobalt pentlandite, Co9S8, at different temperatures using atomistic simulation methods with the support of electronic structure calculations. The first interatomic potentials of Co9S8 were derived with input data as structure and elastic properties from experiment and electronic structure calculations respectively. The potentials were validated by running energy minimization and molecular dynamics calculations. Structure, elastic properties and phonon spectra were well reproduced, together with the complex high temperature transformations and melting of Co9S8 as deduced from crystal structure, radial distribution functions, density profiles and diffusion coefficients. Amongst the high symmetry surfaces {111}, {101} and {101} atomistic surface energy calculations proposed the {111} surface of Co9S8 as the most stable in agreement with experimental morphologies, and water adsorption energies on the such surfaces which mostly agreed with those from electronic structure calculations. The structural and ion transport variations with temperature were investigated and predicted surface melting at lower temperatures than the bulk. The effects of hydration on the surfaces at low and high temperatures were also studied. The structural and ion transport properties of Co9S8 nanoparticles of varying sizes, covered by high symmetry surfaces {111}, {101} and {100} were predicted using molecular dynamics method based on our derived interatomic potentials. The structural and ion transport properties of Co9S8 nanoparticles of varying sizes, covered by high symmetry surfaces {111}, {101} and {100} were predicted using molecular dynamics method based on our derived interatomic potentials. Generally for {111}, {101} nanoparticles, high temperature transitions were abrupt for smaller nanoparticles and these tended to disintegrate and form voids. However, for larger nanoparticles the transitions were more gradual. Transitions in the {100} bound nanoparticles were less dramatic for all sizes and the formation of voids was reduced at high temperatures. Generally, the melting temperatures of different sizes of nanoparticles increases with the particle size hence approach the bulk limit. The interaction of nanoparticles with water was investigated.
Anglo Platinum, National Research Foundation (South Africa), and The Royal Society (UK)

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Mackey, Lisa Catherine. « The ignition properties of pyrite, pyrrhotite pentlandite and violarite ». Curtin University of Technology, Department of Applied Geology, 1991. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=15923.

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The oxidation and ignition behaviour of the four major sulfide minerals present in the nickel concentrates smelted at the Kalgoorlie Nickel Smelter (KNS) has been established. These minerals are pyrite (FeS2), pyrrhotite (Fe1-nS, where n = 0 to 0.125), pentlandite ((FeNi)9S8) and violarite ( Ni2FeS4 ).The characteristic behaviour of these sulfides has been examined using Thermogravimetry-Differential Thermal Analysis (TG-DTA) under normal oxidation conditions ( l0ºC/min, air atmosphere). By increasing the heating rate to 40ºC/min and using an oxygen atmosphere, the tendency of the sulfides to ignite was established. Ignition was characterised by a highly exothermic reaction which occurred in association with a rapid mass loss over a short time span. Significant overheating of the samples beyond the temperature of the surroundings was observed. Pyrite, pyrrhotite and violarite all exhibited ignition behaviour while pentlandite did not.Using Isothermal Thermogravimetry (TG) the sulfides were subjected to shock heating conditions (heating rate = 3000-5000ºC/min, oxygen atmosphere) analogous to those which exist in an industrial flash smelter. The order of reactivity of the sulfides agreed with that observed during TG-DTA ignition trials. Even under these more intensely oxidising conditions pentlandite did not ignite. The effect of particle size on the ignition temperature was determined, larger particles igniting at a higher temperature. The magnitude of this effect varied according to the characteristics of the minerals.Products collected during Isothermal TG were examined by optical microscopy, Scanning Electron Microscopy (SEM) and Electron Probe Microanalysis (EPMA). Using these techniques it was possible to establish the morphology of the products and hence, to propose mechanisms for the reaction of the four sulfide minerals under ignition conditions.In order to ++
simulate the thermal environment which exists in the KNS, a pilot scale model of the reaction shaft was used. Nickel sulfide concentrates of varying mineralogy and particle size distribution were smelted under various conditions. The effect of larger particle size and increasing oxygen partial pressure on the reactivity of these concentrates was established.The products were quenched at the base of the shaft and collected for examination by optical microscopy, SEM and EPMA. Products ranged from unreacted to completely oxidised particles. The morphology and composition of these species were identified. Approximately 30 particles in each of 26 samples were examined with a view to establishing the frequency of occurrence of the particular product types in concentrates of differing mineralogy and particle size. This allowed proposals to be made regarding the fate of the individual sulfide minerals during ignition in the pilot scale flash reactor.

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Shackleton, Natalie Jean. « The role of complexing agents in the flotation of pentlandite-pyroxene mixtures ». Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/10976.

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Bibliography: leaves 137-146.
This study examines the role complexing agents play in pentlandite-pyroxene flotation and focuses on the surface chemistry and interaction between valuable and gangue minerals as well as the interaction of complexing agents and reagents (xanthate, copper sulphate) in the system at pH 9. Microflotation, zeta potential measurements, ToF-SIMS analyses (time of flight secondary ion mass spectrometry) and X-ray photoelectron spectroscopy (XPS) were used as tools in determining the extent of surface alteration.

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Livres sur le sujet "Pentlandit"

Malysiak, Vratislav. Pentlandite-pyroxene and pentlandite-feldspar interactions and their effect on separation by flotation. Cape Town, SA : University of Cape Town, Faculty of Chemical Engineering and Built Environment, 2003.

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Kelly, David Patrick. Pentlandite exsolution in the Fe-Ni-S system : A mechanistic approach to pentlandite/pyrrhotite ore textures. Birmingham : University of Aston. Department of Geological Sciences, 1985.

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Discovering the Pentland Hills. Edinburgh : John Donald, 1991.

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Council, Edinburgh (Scotland) City. Edinburgh Pentlands constituency Register of Electors. Edinburgh : City of Edinburgh Council, 2004.

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Ian, Munro. The birds of the Pentland Hills. Edinburgh : Scottish Academic, 1988.

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Parish life on the Pentland Firth. Thurso : Whitemaa Books, 1997.

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Ferguson, David M. Shipwrecks of Orkney, Shetland, and the Pentland Firth. Newton Abbot, Devon : David & Charles, 1988.

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Pentland hero : The saga of the Orkney short sea crossing. Edinburgh : Birlinn, 2010.

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Fiennes, Ranulph. No Title Exists. Anstey : Thorpe, 1995.

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Lothian (Scotland). Department of Planning. Pentland Hills Regional Park : Subject local plan 1989-1994. (Edinburgh) : Dept. of Planning, Lothian Regional Council, 1989.

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Chapitres de livres sur le sujet "Pentlandit"

Sugaki, Asahiko, et Arashi Kitakaze. « Hydrothermal Synthesis of Pentlandite ». Dans Dynamic Processes of Material Transport and Transformation in the Earth’s Interior, 113–17. Dordrecht : Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-011-3314-2_8.

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Kreitmair, Monika Johanna. « Pentland Firth Study ». Dans The Effect of Uncertainty on Tidal Stream Energy Resource Estimates, 99–109. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-57658-5_6.

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Li, Qian, Huimin Lai, Yongbin Yang, Bin Xu, Tao Jiang et Yaping Zhang. « Effect of Ferric Ions on Bioleaching of Pentlandite Concentrate ». Dans Characterization of Minerals, Metals, and Materials 2016, 345–53. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781119263722.ch42.

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Li, Qian, Huimin Lai, Yongbin Yang, Bin Xu, Tao Jiang et Yaping Zhang. « Effect of Ferric Ions on Bioleaching of Pentlandite Concentrate ». Dans Characterization of Minerals, Metals, and Materials 2016, 345–53. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48210-1_42.

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McDowell, Matthew L. « Thurso and the Pentland Firth as a Site of Sport ». Dans The New Coastal History, 197–214. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-64090-7_12.

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Paniagua-Zambrana, Narel Y., Rainer W. Bussmann, Javier Echeverría et Carolina Romero. « Baccharis alnifolia Meyen & ; Walp. Baccharis boliviensis (Wedd.) Cabrera Baccharis caespitosa (Ruiz & ; Pav.) Pers. Baccharis ciliata Gardner Baccharis indica L. Baccharis juncea (Cass.) Desf. Baccharis pentlandii DC. Baccharis salicifolia (Ruiz & ; Pav.) Pers. Baccharis santelicis Phil. Baccharis tola Phil. Baccharis vaccinioides Kunth Asteraceae ». Dans Ethnobotany of Mountain Regions, 277–89. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-28933-1_33.

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Paniagua-Zambrana, Narel Y., Rainer W. Bussmann, Javier Echeverría et Carolina Romero. « Baccharis alnifolia Meyen & ; Walp. Baccharis boliviensis (Wedd.) Cabrera Baccharis caespitosa (Ruiz & ; Pav.) Pers. Baccharis ciliata Gardner Baccharis indica L. Baccharis juncea (Cass.) Desf. Baccharis pentlandii DC. Baccharis salicifolia (Ruiz & ; Pav.) Pers. Baccharis santelicis Phil. Baccharis tola Phil. Baccharis vaccinioides Kunth Asteraceae ». Dans Ethnobotany of Mountain Regions, 1–13. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-319-77093-2_33-1.

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« Pentlandit m ». Dans Wörterbuch GeoTechnik/Dictionary Geotechnical Engineering, 823. Berlin, Heidelberg : Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-33335-4_160355.

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« pentlandite ». Dans Dictionary Geotechnical Engineering/Wörterbuch GeoTechnik, 975. Berlin, Heidelberg : Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-41714-6_160735.

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« cobalt pentlandite ». Dans Dictionary Geotechnical Engineering/Wörterbuch GeoTechnik, 246. Berlin, Heidelberg : Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-41714-6_32960.

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Actes de conférences sur le sujet "Pentlandit"

Suzuki, Hiromasa, et Shinichi Fukushige. « Elastick : A Vision Based Interface for Designing Spatial Curves and Surfaces ». Dans ASME 2001 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/detc2001/dac-21131.

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Abstract Computer systems are widely used in mechanical design process, but their user interfaces and devices are not sufficient for designers to create sophisticated shapes. Various kinds of 3D input devices are not so useful either in terms of functions and costs. We propose a vision based interface called “Elastick” using an elastic stick and a digital camera which allows a designer to input smooth spatial curve very easily. It does not require any expensive, special devices and environments. The designer bends the stick to form a desired spatial curve. A digital camera is used to take an image of the stick, from which a spatial curve is reconstructed. A method developed by Pentland (PENTLAND, 1989) is used to reconstruct a spatial curve from a single image. In this paper, methods and algorithms used for Elastick are described and its application for generating mesh models are demonstrated.

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Venugopal, Vengatesan, et Reddy Nemalidinne. « Marine Energy Resource Assessment for Orkney and Pentland Waters With a Coupled Wave and Tidal Flow Model ». Dans ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-24027.

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Some preliminary results obtained from a coupled wave and 3D tidal flow numerical model, applied to the Orkney and Pentland waters in the Scottish region of the United Kingdom, are reported in this paper. The coupled wave and flow model was applied to the Orkney Islands comprising a domain of 1.25°W – 5°W and 58.25° N – 59.75°N. The model was run by boundary inputs of wind and water level extracted from European Centre for Medium Range Weather Forecasts (ECMWF) and Danish Hydraulic Institute’s (DHI) global tidal model respectively. The model has been calibrated and validated with wave buoy and ADCP (Acoustic Doppler and Current Profiler) measurements. The depth-wise current velocity components predicted by the model were compared with ADCP measurements for three sites in the Pentland Firth. The results indicated that the coupled model worked well and the tidal current velocities from the model correlated well with ADCP measurements at different depths.

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Mansur, Eduardo, Sarah-Jane Barnes et Charley J. Duran. « AN OVERVIEW OF CHALCOPHILE ELEMENT CONTENTS OF PYRRHOTITE, PENTLANDITE, CHALCOPYRITE AND PYRITE FROM MAGMATIC NI-CU- PGE DEPOSITS ». Dans GSA 2020 Connects Online. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020am-355847.

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Wang, Tuo, et Thomas A. A. Adcock. « Power and Thrust Capping of Tidal Stream Turbines : A Case Study of the Pentland Firth ». Dans ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77079.

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It will not be practical for tidal stream turbines to extract all the peaks in energy over the tidal cycle. It is widely assumed that some form of power capping strategy will be required. In this paper we examine this using a 2D shallow water model of tidal hydrodynamics of the Pentland Firth. We argue that in addition to power capping, it is sensible to control the turbines to limit the peak thrust on them. We show that this can lead to a significant reduction in the peak thrust applied to the turbines and smaller changes to the naturally occurring flow rate whilst having a minimal effect of the mean power generated.

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Ball, Tom, Andrew Black et Alan MacDonald. « 20 year records of spring flows in the Pentland Hills, Midlothian : geological controls and response to drought ». Dans BHS 11th National Hydrology symposium. British Hydrological Society, 2012. http://dx.doi.org/10.7558/bhs.2012.ns06.

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Salary, Roozbeh (Ross), Jack P. Lombardi, Prahalad K. Rao et Mark D. Poliks. « Additive Manufacturing (AM) of Flexible Electronic Devices : Online Monitoring of 3D Line Topology in Aerosol Jet Printing Process Using Shape-From-Shading (SfS) Image Analysis ». Dans ASME 2017 12th International Manufacturing Science and Engineering Conference collocated with the JSME/ASME 2017 6th International Conference on Materials and Processing. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/msec2017-2947.

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The goal of this work is online quality monitoring of flexible electronic devices made using Aerosol jet printing (AJP) additive manufacturing (AM) process. In pursuit of this goal, the objective is to recover and quantify the 3D topology of AJP-printed electronic traces (lines) through in situ images. The intent is to use the estimated 3D topology for online prediction of the device electrical performance characteristics. To realize this objective different shape-from-shading (SfS) techniques are tested to recover the 3D topology of lines from high resolution in situ 2D images. These images are obtained from a CCD camera installed on our experimental Optomec AJ300 AJP setup. White light interferometry is used offline to verify the online experimental trends. Three types of SfS algorithms are tested, namely, minimization method, Pentland’s method, and Shah’s method. Tests with synthetic images and experimental data indicate that Shah’s method is more suitable. The correlation between online and offline estimates of line thickness was ∼80%.

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McCann, David L., et Paul S. Bell. « Marine radar derived current vector mapping at a planned commercial tidal stream turbine array in the Pentland Firth, U.K. » Dans OCEANS 2014. IEEE, 2014. http://dx.doi.org/10.1109/oceans.2014.7003186.

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Venugopal, Vengatesan, et Arne Vögler. « Modelling Wave-Current-Turbulence Interactions for Tidal Energy Applications ». Dans ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-19298.

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Abstract This paper presents the nature of turbulence parameters produced from 3-dimensional numerical simulations using an ocean scale wave-tidal current model applied to tidal energy sites in the Orkney waters in the United Kingdom. The MIKE 21/3 coupled wave-current model is chosen for this study. The numerical modelling study is conducted in two stages. First, a North Atlantic Ocean large-scale wave model is employed to simulate wave parameters. Spatial and temporal wind speeds extracted from the European Centre for Medium Range Weather Forecast (ECMWF) is utilised to drive the North Atlantic wave model. Secondly, the wave parameters produced from the North Atlantic model are used as boundary conditions to run a coupled wave-tidal current model. A turbulence model representing the turbulence and eddy viscosity within the coupled model is chosen and the turbulence kinetic energy (TKE) due to wave-current interactions are computed. The coupled model is calibrated with Acoustic Doppler and Current Profiler (ADCP) measurements deployed close to a tidal energy site in the Inner Sound of the Pentland Firth. The model output parameters such as the current speed, TKE, horizontal and vertical eddy viscosities, significant wave height, peak wave period and wave directions are presented, and, their characteristics are discussed in detail.

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Griffiths, Terry, Scott Draper, Liang Cheng, Feifei Tong, Antonino Fogliani, David White, Fraser Johnson, Daniel Coles, Stephen Ingham et Caroline Lourie. « Subsea Cable Stability on Rocky Seabeds : Comparison of Field Observations Against Conventional and Novel Design Methods ». Dans ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77130.

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As offshore renewable energy projects progress from concept demonstration to commercial-scale developments there is a need for improved approaches beyond conventional cable engineering design methods that have evolved from larger diameter pipelines for the oil and gas industry. New approaches are needed to capture the relevant physics for small diameter cables on rocky seabeds to reduce the costs and risks of power transmission and increase operational reliability. This paper reports on subsea cables that MeyGen installed for Phase 1a of the Pentland Firth Inner Sound tidal stream energy project. These cables are located on rocky seabeds in an area where severe metocean conditions occur. ROV field observation of these cables shows them to be stable on the seabed with little or no movement occurring over almost all of the cable routes, despite conventional engineering methods predicting significant dynamic movement. We cite recent research undertaken by the University of Western Australia (UWA) to more accurately assess the hydrodynamic forces and geotechnical interaction of cables on rocky seabeds. We quantify the conformity between the cables and the undulating rocky seabed, and the distributions of cable-seabed contact and spanning via simulations of the centimetric-scale seabed bathymetry. This analysis leads to calculated profiles of lift, drag and seabed friction along the cable, which show that all of these load and reaction components are modelled in an over-conservative way by conventional pipeline engineering techniques. Overall, our analysis highlights that current cable stability design can be unnecessarily conservative on rocky seabeds. Our work foreshadows a new design approach that offers more efficient cable design to reduce project capex and enhance through-life integrity management.

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