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1
Mhonde, Ngoni, Mariette Smart, Kirsten Corin e Nora Schreithofer. "Investigating the Electrochemical Interaction of a Thiol Collector with Chalcopyrite and Galena in the Presence of a Mixed Microbial Community". Minerals 10, n. 6 (19 giugno 2020): 553. http://dx.doi.org/10.3390/min10060553.
Testo completoAbstract (sommario):
High microbial cell counts have been recorded in sewage waters employed as process water in mineral beneficiation plants across the world. The presence of these microbes can negatively impact flotation performance through mineral passivation, although some microbes improve flotation performance as investigated in various bio-flotation studies. The current study aims to understand the electrochemical behaviour of minerals in the presence of a sodium ethyl xanthate (SEX) collector and microbes originating from a sulphide ore processing plant in South Africa. The electrochemical response was correlated to observe flotation performance. Mixed potential measurements were conducted in parallel to microflotation tests, to assess the hydrophilicity or hydrophobicity induced on sulphide minerals adapted to microbe-laden synthetic plant water. Sulphide minerals’ mixed potentials and interactions of SEX with sulphide minerals were dramatically reduced in the presence of the mixed microbial community (MMC). The observations were correlated with poor flotation efficacy noted in microflotation tests. These fundamental results shed light on how the adsorption of thiol collectors on sulphide minerals is adversely affected by microbes, prompting a discussion on flotation process monitoring when mineral beneficiation is conducted using microbe-laden water.
2
Firstova, Anna, Tamara Stepanova, Anna Sukhanova, Georgy Cherkashov e Irina Poroshina. "Au and Te Minerals in Seafloor Massive Sulphides from Semyenov-2 Hydrothermal Field, Mid-Atlantic Ridge". Minerals 9, n. 5 (15 maggio 2019): 294. http://dx.doi.org/10.3390/min9050294.
Testo completoAbstract (sommario):
The Semyenov-2 hydrothermal field located at 13°31′N of the Mid-Atlantic Ridge (MAR) is associated with an oceanic core complex (OCC) and hosted by peridotites and basalts with minor amounts of gabbro and plagiogranites. Seafloor massive sulphides (SMS) are represented by chimneys with zonality, massive sulphides without zonality and sulphide breccia cemented by opal and aragonite. The mean value of Au (20.6 ppm) and Te (40 ppm) is much higher than average for the MAR SMS deposits (3.2 ppm and 8.0 ppm, respectively). Generally, these high concentrations reflect the presence of a wide diversity of Au and Te minerals associated with major mineral paragenesis: primary native gold, melonite (NiTe2) and tellurobismuthite (Bi2Te3) are related to high-temperature chalcopyrite (~350 °C); electrum (AuAg)1, hessite (Ag2Te) and altaite (PbTe) are related to medium- and low-temperature Zn-sulphide and opal assemblages (260–230 °C). Calaverite (AuTe2) and Te-rich “fahlore” Cu12(Sb,As,Te)4S13 are texturally related to the chalcopyrite-bornite-covellite. Enrichment of Au in sulphide breccia with opal and aragonite cement is driven by the re-deposition and the process of hydrothermal reworking of sulphide. The low-temperature fluid mobilizes gold from primary sulphide, along with Au and Te minerals. As a result, the secondary gold re-precipitate in cement of sulphide breccia. An additional contribution of Au enrichment is the presence of aragonite in the Cu-Zn breccia where the maximal Au content (188 ppm) is reached.
3
Nghipulile, T., T. E. Moongo, G. Dzinomwa, K. Maweja, B. Mapani, J. Kurasha e M. Amwaama. "Effect of mineralogy on grindability -A case study of copper ores". Journal of the Southern African Institute of Mining and Metallurgy 123, n. 3 (14 aprile 2023): 133–44. http://dx.doi.org/10.17159/2411-9717/1714/2023.
Testo completoAbstract (sommario):
The effect of mineralogy on the grindability was investigated using three copper ores - two sulphides and one oxide. The dominant copper minerals were identified by optical microscopy and mineral chemistry derived from SEM-EDS analysis. The sample designated sulphide 1 was bornite-rich, sulphide 2 ore was mainly chalcopyrite, and the oxide ore was predominantly malachite and minor azurite. The gangue minerals were identified using semi-qualitative XRD analysis. Sulphide 1 contained more than 80% (w/w) of quartz compared to about 70% in the other two ores. The Bond work indices were 13.8, 21.6, and 17.3 kWh/t for sulphide 1, sulphide 2, and oxide ore respectively. This suggested that the chalcopyrite-rich ore is the hardest, while the malachite-rich ore has intermediate hardness, and the bornite-rich ore is the softest. The brittleness indices of the ores were calculated using the chemical composition of the gangue, and a good correlation between brittleness indices and Bond work indices was observed, which highlights the importance of the gangue composition in determining the fracture behaviour of the ores. There is scope for further investigation into the relationship between ore mineralogy and comminution behaviour using other breakage characterization techniques.
4
Belogub, E. V., C. A. Novoselov, B. Spiro e B. A. Yakovleva. "Mineralogical and S isotopic features of the supergene profile of the Zapadno-Ozernoe massive sulphide and Au-bearing gossan deposit, South Urals". Mineralogical Magazine 67, n. 2 (aprile 2003): 339–54. http://dx.doi.org/10.1180/0026461036720105.
Testo completoAbstract (sommario):
The profile of the supergene zone of the Zapadno-Ozernoe massive sulphide Cu-Zn deposit differs from the classic model (Emmons, 1917) in that it includes a prominent dark sooty subzone rich in secondary sulphides. This subzone is situated above residual pyrite sands, which overlie the massive sulphide body and below quartz-baryte leached sands. It contains a diverse mineral assemblage which consists of secondary sulphides such as galena, sphalerite, metacinnabar, Se-bearing pyrite—dhzarkenite series, tiemannite, native Au, native S and native Se, and unidentified sulphosalts of Ag and Hg. The very light S isotope composition of the secondary sulphides (lowest values δ34S = —17.2‰ (VCDt) in comparison with primary pyrite ∼0‰ and baryte +18.4‰ is indicative of bacterial sulphate reduction. The overlying oxidized part of the supergene column contains minerals of the jarosite-beudantite- segnitite series. The maximum concentrations of Au, up to 150 ppm, occur in the lower part of the profile. The atypical structure, mineral assemblage and S isotope composition of the secondary sulphides in the dark layer of the supergene profile are indicative of particular geochemical conditions due to the existence of a stagnant water body that gave rise to intense bacterial activity, in turn controlled by fluctuations in the redox boundary.
5
Wilton, Derek H. C., Benoit M. Saumur, Adrian Gordon e Marie-Claude Williamson. "Enigmatic massive sulphide mineralization in the High Arctic Large Igneous Province, Nunavut, Canada". Canadian Journal of Earth Sciences 56, n. 7 (luglio 2019): 790–801. http://dx.doi.org/10.1139/cjes-2018-0156.
Testo completoAbstract (sommario):
Modern mineral exploration strategies should take into account nontraditional metallogenic models for a given geological environment. Here we document the first detailed study of a massive sulphide showing associated with the High Arctic Large Igneous Province (HALIP) and Sverdrup Basin and in fact, only the second example of mineralization described from Axel Heiberg Island, Queen Elizabeth Islands, Canadian Arctic Archipelago. The Between Lake showing (western Axel Heiberg Island) is a small massive sulphide occurrence within scree/talus below a large ridge of gabbro. It was originally described by explorationists as an orthomagmatic sulphide occurrence hosted within a dioritic dyke. New petrographic and mineralogical analyses indicate that the showing consists predominantly of pyrrhotite with lesser pyrite, trace chalcopyrite, and rare sphalerite. No Ni- or Pb-bearing sulphide minerals were detected. Geochemically, the showing contains some Co and Cu, rare Zn, and generally very low Ni contents (<9 ppm). Sulphur isotope ratios of sulphide minerals range from +3.6 to + 6.6‰, somewhat heavier than expected for magmatic-derived S but isotopically lighter than S associated with local evaporite diapirs (+5.8‰ to +12.2‰). Orthomagmatic sulphides hosted in the diorite typically exhibit even lighter isotopic ratios of –3.9‰ to –1.00‰. The data are consistent with potential mafic–siliciclastic volcanogenic massive sulphide mineralization, or the like, the first documented in the HALIP. High heat flow associated with extensive HALIP magmatism was likely the driving force for such mineralization. Mineral prospectivity in Canada’s High Arctic had been predicated upon the potential presence of magmatic Ni – Cu – platinum group element sulphide mineralization. Rather than negating this potential, our findings provide evidence for additional metallogenic potential for this region of Nunavut.
6
Merkle, Roland K. W. "Platinum-group minerals in the middle group of chromitite layers at Marikana, western Bushveld Complex: indications for collection mechanisms and postmagmatic modification". Canadian Journal of Earth Sciences 29, n. 2 (1 febbraio 1992): 209–21. http://dx.doi.org/10.1139/e92-020.
Testo completoAbstract (sommario):
The platinum-group minerals in a drill core taken through the middle group of chromitite layers in the Critical Zone at Marikana in the western Bushveld Complex were found to consist mainly of laurite as inclusions in chromite grains. The platinum-group minerals containing Pt, Pd, and Rh are concentrated in the intercumulus silicates and frequently associated with base-metal sulphides. Up to about 20% of all platinum-group minerals in the investigated chromitite layers contain sub stantial amounts of As. The base-metal sulphides are strongly modified in the postmagmatic stage, which led to a significant loss of Fe and S, in this way concentrating Cu, Ni, and the platinum-group elements by factors of up to 10. Interaction between chromite and base-metal sulphides cannot account for all the Fe lost in chromite-poor samples, and the importance of additional processes is indicated. Inclusions in chromite and orthopyroxene indicate the formation of discrete platinum-group minerals and As-rich phases before the formation of an immiscible sulphide melt. Resorption of earlier formed platinum-group minerals into the immiscible sulphide melt and postmagmatic sulphidation destroyed most of the evidence of the early formed platinum-group minerals.
7
Parnell, John, Sean McMahon e Adrian Boyce. "Demonstrating deep biosphere activity in the geological record of lake sediments, on Earth and Mars". International Journal of Astrobiology 17, n. 4 (2 ottobre 2017): 380–85. http://dx.doi.org/10.1017/s1473550417000337.
Testo completoAbstract (sommario):
AbstractThe investigation of Gale Crater has highlighted the occurrence of lake sediments in the geological record of Mars. Lacustrine basins include a diversity of potential habitats for life. An analogue terrestrial lacustrine basin of Devonian age in Scotland contains sulphide minerals in several settings where subsurface microbial colonization can be envisaged. Sulphur isotope compositions for the sulphides imply that they were precipitated by microbial sulphate reduction. The data suggest that the search for life in martian lacustrine basins should include investigation of potential subsurface habitats, and that any sulphides in martian lacustrine basins could be useful indicators in the search for life.
8
Cook, Nigel J., Christopher Halls e Alan P. Boyle. "Deformation and metamorphism of massive sulphides at Sulitjelma, Norway". Mineralogical Magazine 57, n. 386 (marzo 1993): 67–81. http://dx.doi.org/10.1180/minmag.1993.057.386.07.
Testo completoAbstract (sommario):
AbstractThe copper-bearing stratabound pyritic massive sulphide bodies contained in metamorphosed basic eruptives of Ordovician age at Sulitjelma in Nordland County, Norway, form one of the important fields of sulphide mineralisation within the Köli Nappe Complex. The sulphide bodies and their enclosing rocks were subject to successive stages of penetrative deformation and recrystallisation during the cycle of metamorphism and tectonic transport caused by the Scandian Orogeny. Textures within the ores and the immediate envelope of schists show that strain was focused along the mineralised horizons. The marked contrast in competence between the massive pyritic sulphides and their envelopes of alteration composed dominantly of phyllosilicates, and the metasediments of the overlying Furulund Group, led to the formation of macroscale fold and shear structures. On the mesoto microscale, a variety of textures have been formed within the pyrite-pyrrhotite-chalcopyrite-sphalerite sulphide rocks as a result of strain and recrystallisation. Variations in pyrite:pyrrhotite ratios and in the texture and proportions of associated gangue minerals evidently governed the strength and ductility of the sulphide rocks so that the same sulphide mineral can behave differently, displaying different textures in different matrices. In massive pyritic samples there is evidence of evolution towards textural equilibrium by recrystallisation, grain growth and annealment during the prograde part of the metamorphic cycle. Later, brittle deformation was superimposed on these early fabrics and the textural evidence is clearly preserved. By comparing published data on the brittle-ductile transformation boundaries of sulphide minerals with the conditions governing metamorphism at Sulitjelma, it is concluded that most of the brittle deformation in the sulphides took place during or after D3under retrograde greenschist conditions. Grain growth of pyrite in matrices of more ductile sulphides during the prograde and early retrograde stages of metamorphism produced the coarse metablastic textures for which Sulitjelma is well-known. In some zones of high resolved shear stress, pyrite shows ductile behaviour which could be explained by a dislocation flow mechanism operating at conditions close to the metamorphic peak. In those horizons in which pyrrhotite is the dominant iron sulphide, the contrast in ductility between silicates, pyrite and pyrrhotite has led to the development of spectacular tectonoclastic textures in which fragments of wall rock have been broken, deformed, rolled and rotated within the ductile pyrrhotite matrix.
9
Kim, Heekang, Frank Rosenblum, Ozan Kökkılıç e Kristian Waters. "Role of Elemental Sulphur in Stage B Self-Heating of Sulphide Minerals, and the Potential Role of Polysulphides". Minerals 13, n. 7 (8 luglio 2023): 923. http://dx.doi.org/10.3390/min13070923.
Testo completoAbstract (sommario):
Sulphide minerals undergo numerous stages of mineral processing to extract the desired metal. When they are exposed to certain environmental conditions, some sulphide minerals can spontaneously heat up, a process called self-heating (SH), which, if left unchecked, can be a major hazard. Self-heating occurs in three distinct temperature stages, termed Stage A (temperature below 100 °C), Stage B (temperature range of 100 °C–350 °C), and Stage C (above 350 °C). Historically, it was understood that elemental sulphur generated in Stage A fuels Stage B reactions; however, the full extent of this behaviour is still unknown. The aim of this study is to understand the role of elemental sulphur in Stage B reactions. The results have demonstrated that elemental sulphur is incapable of fueling Stage B self-heating on its own, and it needs to interact with sulphide minerals in ambient temperatures in the presence of moisture and air. This interaction seems to be unique to pyrrhotite, as it failed to demonstrate stage B self-heating with other sulphide minerals. Previous works in surface chemistry suggest that this interaction leads to the formation of polysulphides.
10
Dekov, Vesselin, Elena Mandova e Vera Kazakova. "Mineralogical genetic groups of fine-psammitic and coarse-aleuritic fractions and some indicators of the submarine hydrothermal activity history (East Pacific Rise, 21°S)". Geologica Balcanica 24, n. 3 (30 giugno 1994): 63–75. http://dx.doi.org/10.52321/geolbalc.24.3.63.
Testo completoAbstract (sommario):
The mineral composition of fine-psammitic (0.10-0.50 mm) and coarse-aleuritic (0.05-0.10 mm) fractions of metalliferous sediments from the East Pacific Rise axial zone (20°30'-22°00' S) is investigated in details by a complex of analytical methods. The mineral composition of the sediments of this region is controlled by the follow factors: remoteness from the landmasses; ocean depth; appurtenance of investigated area to the South arid zone and the axial part of the fast spreading centre with high hydrothermal activity. The sedimentary formation of the investigated spreading segment is polygenetic. Seven mineralogical genetic groups can be distinguished: biogenous, terrigenous, hydrothermal, basaltic, diagenetic, hydrogenetic and cosmogenic. The pelagic background is formed mainly by biogenous CaCO3 and detrital and clay minerals with eolic origin. The diagenetic and hydrogenetic mineral formation have subordinate significance in that environment. The tectonovolcanic processes in the region supply a specific "local" material to the sediments - basaltic and hydrothermal. Some of the minerals accumulating in the metalliferous sediments of the spreading sedimentary formation can be recommended as indicators for sulphide ore prospecting. The sulphides of Fe, Cu, Zn; barite; Fe umbers; compact black-brown Fe crusts; black Mn crusts; colloform semitransparent aggregates of Fe oxyhydroxydes and amorphous SiO2 are the best indicators for sulphide mineralization in the investigated area. Their contents increase regularly towards the hydrothermal fields. The spatial distribution of the minerals related to the hydrothermal activity in the rift is controlled by the rate and direction of the seabottom currents and by the hydrothermal system locality and power. A regular variation of the mineral composition of the investigated fractions is established during cyclic tectono-volcanic development of the spreading centre. The content of basaltic minerals increases during the volcanic cycles (before and after the hydrothermal cycles). The concentration of hydrothermal-sedimentary minerals in the sediments increases during the hydrothermal cycles. Low-temperature minerals are formed during their initial and final phases.
11
Mhonde, Ngoni, Nora Schreithofer, Kirsten Corin e Mikko Mäkelä. "Assessing the Combined Effect of Water Temperature and Complex Water Matrices on Xanthate Adsorption Using Multiple Linear Regression". Minerals 10, n. 9 (19 agosto 2020): 733. http://dx.doi.org/10.3390/min10090733.
Testo completoAbstract (sommario):
The combined effect of dissolved ions and water temperature on the adsorption of a xanthate collector on chalcopyrite and pentlandite was investigated using multiple linear regression. Cationic species improved the adsorption of the collector on sulphide minerals through xanthate adsorption activation. Thiosulphate ions generally had a negative effect on collector adsorption, and the interaction of thiosulphate ions and cations effectively reduced collector adsorption on the sulphide minerals. With regards to temperature variation caused by seasonal variation, this study suggests that temperature can influence the adsorption of collectors in the flotation process and this should be approached on a case by case basis as it seems to differ with the type of mineral under investigation. These fundamental results prompt a discussion on how complex water matrices can affect interactions of reagents and sulphide minerals at the solid–liquid interface and the possible effect on flotation performance.
12
Zhao, Li Bing, e Yue Xin Han. "Study on Size Distribution of the Copper and Nickel Ore". Advanced Materials Research 92 (gennaio 2010): 221–27. http://dx.doi.org/10.4028/www.scientific.net/amr.92.221.
Testo completoAbstract (sommario):
Mineralogy research of the copper and nickel ore from Jinchuan is completed in detail that shows the mineral compositions and their percentage and particle size distributions of the valuable minerals. The main valuable minerals are pyrite, violarite, chalcopyrite which are closely associated with other sulphide minerals. These results provide an important basis for the beneficiation tests.
13
Mitchell, R. H., e F. Belton. "Niocalite-cuspidine solid solution and manganoan monticellite from natrocarbonatite, Oldoinyo Lengai, Tanzania". Mineralogical Magazine 68, n. 5 (ottobre 2004): 787–99. http://dx.doi.org/10.1180/0026461046850219.
Testo completoAbstract (sommario):
AbstractLapilli and spatter of natrocarbonatite extruded from the T56B cone of Oldoinyo Lengai (Tanzania) in August 2003 are unusually rich in apatite, silicate, oxide and sulphide minerals. These minerals occur primarily within inclusions of quenched natrocarbonatite in gregoryite and fractures in nyerereite-gregoryite intergrowths. Silicates include members of the sodian cuspidine–niobian cuspidine–niocalite solid-solution series and manganoan monticellite. Oxides are represented by members of the magnesioferrite–jacobsite–magnetite solid-solution series. Sulphides occurring in decreasing order of abundance include: ferroan alabandite, manganoan ferroan sphalerite, galena and pyrrhotite. Petrographic and compositional data for these minerals are interpreted to indicate that all are high-temperature (<900–650°C), early-crystallizing phases from relatively-unevolved natrocarbonatite magma, with the sulphides forming prior to the silicates, and the latter before gregoryite. Sulphur fugacityand oxygen fugacity of natrocarbonatite magma are considered to decrease and increase, respectively, during the formation of the sulphide-oxide assemblage. Crystallization of cuspidine-niocalite, monticellite and Si-bearing apatite rapidly depletes natrocarbonatite magma of its initial low silica content, preventing crystallization of late-stage groundmass silicates.
14
Jasiński, A. W. "Conditions of formation of the iron-containing minerals, Hällefors silver mines, Bergslagen, Sweden". Mineralogical Magazine 50, n. 355 (marzo 1986): 101–10. http://dx.doi.org/10.1180/minmag.1986.050.355.13.
Testo completoAbstract (sommario):
AbstractThe Hällefors silver deposit is regarded as a volcanogenic-exhalative iron ore deposit with dispersed amounts of Ag-Pb-Zn (±Cu) which has undergone secondary remobilization leading to the concentration of sulphides and sulphosalts. Based on data from the iron oxides and sulphides, the sulphide-sulphosalt mineralization is believed to have been formed in two stages. The first is characterized by the ranges 573-473 K and 2.25–1.5 kbar, higher gradient of changes of log aS2 with temperature and mostly sulphide precipitation; the second by the ranges 473–443 K, lower gradient of changes of log aS2 and mainly sulphosalt deposition. Assuming the precipitation was from fluids and aqueous solutions, possible conditions of formation of some of the iron minerals have been determined.
15
HAYES, R. A., D. M. PRICE, J. RALSTON e R. W. SMITH. "Collectorless Flotation of Sulphide Minerals". Mineral Processing and Extractive Metallurgy Review 2, n. 3 (marzo 1987): 203–34. http://dx.doi.org/10.1080/08827508708952606.
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Han, Kenneth N. "Flotation of sulphide minerals 1990". International Journal of Mineral Processing 36, n. 3-4 (ottobre 1992): 295–96. http://dx.doi.org/10.1016/0301-7516(92)90051-w.
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17
Mielczarski, Jerzy. "Flotation of sulphide minerals 1990". International Journal of Mineral Processing 38, n. 1-2 (maggio 1993): 154–56. http://dx.doi.org/10.1016/0301-7516(93)90072-i.
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Cox, S. F. "Flow mechanisms in sulphide minerals". Ore Geology Reviews 2, n. 1-3 (maggio 1987): 133–71. http://dx.doi.org/10.1016/0169-1368(87)90026-6.
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19
Dunn, J. G. "The oxidation of sulphide minerals". Thermochimica Acta 300, n. 1-2 (ottobre 1997): 127–39. http://dx.doi.org/10.1016/s0040-6031(96)03132-2.
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20
Vikentyev, Ilya, Olga Vikent’eva, Eugenia Tyukova, Maximilian Nikolsky, Julia Ivanova, Nina Sidorova, Dmitry Tonkacheev et al. "Noble Metal Speciations in Hydrothermal Sulphides". Minerals 11, n. 5 (3 maggio 2021): 488. http://dx.doi.org/10.3390/min11050488.
Testo completoAbstract (sommario):
A significant part of the primary gold reserves in the world is contained in sulphide ores, many types of which are refractory in gold processing. The deposits of refractory sulphide ores will be the main potential source of gold production in the future. The refractory gold and silver in sulphide ores can be associated with micro- and nano-sized inclusions of Au and Ag minerals as well as isomorphous, adsorbed and other species of noble metals (NM) not thoroughly investigated. For gold and gold-bearing deposits of the Urals, distribution and forms of NM were studied in base metal sulphides by laser ablation-inductively coupled plasma mass spectrometry and by neutron activation analysis. Composition of arsenopyrite and As-pyrite, proper Au and Ag minerals were identified using electron probe microanalysis. The ratio of various forms of invisible gold—which includes nanoparticles and chemically bound gold—in sulphides is discussed. Observations were also performed on about 120 synthetic crystals of NM-doped sphalerite and greenockite. In VMS ores with increasing metamorphism, CAu and CAg in the major sulphides (sphalerite, chalcopyrite, pyrite) generally decrease. A portion of invisible gold also decreases —from ~65–85% to ~35–60% of the total Au. As a result of recrystallisation of ores, the invisible gold is enlarged and passes into the visible state as native gold, Au-Ag tellurides and sulphides. In the gold deposits of the Urals, the portion of invisible gold is usually <30% of the bulk Au.
21
Hutabarat, Imelda. "Thermal analysis of Indonesian copper sulphide". IOP Conference Series: Earth and Environmental Science 882, n. 1 (1 novembre 2021): 012009. http://dx.doi.org/10.1088/1755-1315/882/1/012009.
Testo completoAbstract (sommario):
Abstract The development of extracting hydrometallurgical process for copper sulphide mineral becomes one of the promising fields, not only for the copper production but also for the production of metal by-products. The advantage of the thermal analysis is to get the phase form of the minerals on a certain temperature. With this result, the chosen metal can be selectively extracted. The goal of this study is to understand the thermal reaction of the copper sulphide as the basic data to develop a process flowsheet of extracting copper and other important metals from the copper concentrates by using an alternative new hydrometallurgy process to increase the value of the minerals. The thermal behaviour was investigated by simultaneous thermal analysis consisting of differential scanning calorimetry (DSC) in combination with thermo gravimetry (TG) and fourier transform infrared (FTIR) spectroscopy. Samples were pre-treated by roasting at the several temperature transitions and subsequently characterized by XRD and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS).
22
Abraitis, P. K., R. A. D. Pattrick, G. H. Kelsall e D. J. Vaughan. "Acid leaching and dissolution of major sulphide ore minerals: processes and galvanic effects in complex systems". Mineralogical Magazine 68, n. 2 (aprile 2004): 343–51. http://dx.doi.org/10.1180/0026461046820191.
Testo completoAbstract (sommario):
AbstractThe kinetics and mechanisms of dissolution of the major base metal sulphide minerals, pyrite, chalcopyrite, galena and sphalerite in acidic (chloride) media have been investigated. Minerals were ground in air, then dissolved in air-equilibrated solutions at pH 2.5, while monitoring the redox potential. Solution samples were analysed by ICP-AES and HPLC, and surfaces of residual sulphides analysed using XPS. Dissolution of aerial oxidation products on pyrite particles in the first 15 min apparently led to a sulphur-rich surface, and was followed by slower dissolution of pyrite itself, driven by oxygen reduction, and resulting in net production of protons. Chalcopyrite dissolution resulted in a Cu, S-rich (near) surface layer, accompanied by net consumption of protons. Apparently incongruent dissolution of galena and sphalerite may reflect the formation of elemental S at the surface. The rates of dissolution of chalcopyrite, galena and sphalerite in the presence of pyrite were determined, respectively, as 18, 31 and 1.5 times more rapid than in single-mineral experiments. These data were consistent with galvanically-promoted mineral oxidation of the other sulphides in the presence of pyrite. In the case of galena, the experimental data suggested extensive release of Pb ions and development of a sulphur-rich surface during galvanically-promoted dissolution.
23
Tafirenyika, Tanaka P., Cyril T. O’Connor e Kirsten C. Corin. "Investigating the Influence of the Electrochemical Environment on the Flotation of Bornite and Chalcocite". Minerals 12, n. 12 (28 novembre 2022): 1527. http://dx.doi.org/10.3390/min12121527.
Testo completoAbstract (sommario):
Beneficiation of sulphide ores by flotation is ascribed to the natural electrochemical activity associated with sulphide minerals. Flotation is an electrochemical process comprising many interdependent conditions that are difficult to decouple in terms of controlling flotation performance. The extent of electrochemical activity is mineral dependent and can be measured against a reference cell to differentiate between minerals. This difference in activity is known as the rest potential. The rest potential can be exploited to preferentially float one mineral over another as these properties result in different regions of flotation stability for different minerals. Bornite and chalcocite present an interesting study because when measured against the standard hydrogen electrode (SHE), there is a small difference in rest potential; bornite has a potential of 0.44 V and chalcocite a potential of 0.40 V. The key differentiating factor between the two minerals is the presence of iron in bornite (Cu5FeS4) and the lack thereof in chalcocite (Cu2S). This study considers bornite and chalcocite microflotation, adsorption studies and zeta potential measurements, and three key factors were explored: pH, galvanic interactions and collector adsorption. The overall objective of the study is to understand the response of bornite and chalcocite to changes in pulp chemistry.
24
Sokić, Miroslav D., Vladislav Matković, Jovica Stojanović, Branislav Marković e Vaso Manojlović. "Kinetics of barite reduction from refractory barite-sulphide ore". Metallurgical and Materials Engineering 22, n. 4 (31 dicembre 2016): 261–68. http://dx.doi.org/10.30544/237.
Testo completoAbstract (sommario):
Refractory sulphide–barite ore was reduced with carbon in order to release lead, zinc, and copper sulphide from barite-pyrite base. Mineralogical investigations showed that due to the complex structural-textural relationships of lead, copper and zinc minerals with gangue minerals, it is not possible to enrich the ore using the conventional methods of mineral processing. The influence of temperature and time was studied to optimize the conditions, and to determine the kinetics of the barite reduction. The maximum removal of barite from ore was 96.7% at 900oC after 180 min. Chemically controlled kinetic model showed the best compliance with the experimental data. An activation energy of 142 kJ/mol was found.
25
Rao, S. R., e J. A. Finch. "Galvanic Interaction Studies on Sulphide Minerals". Canadian Metallurgical Quarterly 27, n. 4 (ottobre 1988): 253–59. http://dx.doi.org/10.1179/cmq.1988.27.4.253.
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Furukawa, Y. "Replacement Mechanisms Among Iron Sulphide Minerals". Mineralogical Magazine 58A, n. 1 (1994): 299–300. http://dx.doi.org/10.1180/minmag.1994.58a.1.157.
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Baláž, P., A. Aláčová, M. Achimovičová, J. Ficeriová e E. Godočíková. "Mechanochemistry in hydrometallurgy of sulphide minerals". Hydrometallurgy 77, n. 1-2 (aprile 2005): 9–17. http://dx.doi.org/10.1016/j.hydromet.2004.09.009.
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SOROKA, Elena Industrovna, Lyubov’ Vladimirovna LEONOVA e Mikhail Egorovich PRITCHIN. "Brockite in wallrock metasomatites of the Safyanovskoe copper-sulphide deposit (Middle Urals)". NEWS of the Ural State Mining University 59, n. 3 (15 settembre 2020): 35–40. http://dx.doi.org/10.21440/2307-2091-2020-3-35-40.
Testo completoAbstract (sommario):
The relevance of the work is due to the need to study ore copper-sulphide deposits in the Urals. Purpose of the work: description of accessory brockite in metasomatites of the Safyanovskoe copper-sulphide deposit. Research methodology: the chemical composition of minerals was determined using the Jeol JSM-6390LV scanning electron microscope with an INCA Energy 450 X-Max 80 energy dispersive attachment from Oxford Instruments (Institute of Geology and Geochemistry of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg). Results and conclusions. For the first time for the Safyanovskoe copper-sulphide deposit (Middle Urals), an aqueous rare earth phosphate of calcium and thorium, brockite, has been determined; it belongs to the group of rhabdophane (Ca,Th,REE)[PO]4 ∙ _H2 O. The mineral is rare for the Urals and was described earlier in granite pegmatites of the Middle and South Urals, as well as in dikes of metaplagiogranites of the Bazhenov ophiolite complex. Brockite was found in the rocky metasomatites of the Safyanovskoe copper-sulphide deposit after crystalline lithoclastic tuff (tuffaceous sandstone) of acid composition. The main mass of the rock consists of quartz, kaolinite (sericite), carbonates (dolomite, Fe-magnesite) with rare inclusions of pyrite. Brockite is found in the dolomite-quartz matrix of the sample in intergrowths with REE-goyazite – strontium aluminophosphate. It is assumed for the Safyanovskoe copper-sulphide deposit that an alumina association with an ore mineral association and rare earth minerals, in particular, REE-alumophosphates and phosphates, will form closely at the same time as the temperature drops and the redox conditions of the mineral formation environment change.
29
Gilbert, S. E., L. V. Danyushevsky, K. Goemann e D. Death. "Fractionation of sulphur relative to iron during laser ablation-ICP-MS analyses of sulphide minerals: implications for quantification". J. Anal. At. Spectrom. 29, n. 6 (2014): 1024–33. http://dx.doi.org/10.1039/c4ja00012a.
Testo completoAbstract (sommario):
In this study we investigate the effect that the mineral composition has on the quantification of sulphur by Laser Ablation ICP-MS (LA-ICP-MS) between a range of sulphide minerals: pyrite, pyrrhotite, bornite, chalcopyrite, sphalerite, pentlandite and tetrahedrite.
30
Raiswell, R., L. G. Benning, L. Davidson e M. Tranter. "Nanoparticulate bioavailable iron minerals in icebergs and glaciers". Mineralogical Magazine 72, n. 1 (febbraio 2008): 345–48. http://dx.doi.org/10.1180/minmag.2008.072.1.345.
Testo completoAbstract (sommario):
AbstractIce-hosted sediments in glaciers and icebergs from Antarctica and Svalbard contain authigenic nanoparticulates of schwertmannite, ferrihydrite and goethite that formed during sulphide oxidation. These phases indicate the existence of subglacial biogeochemical hotspots containing fluids of low pH (2—4), rich in dissolved Fe(III) and sulphate. Nanophase Fe is partially bioavailable and potentially important to global biogeochemical cycles, since the flux delivered by icebergs to the Southern Ocean is comparable to the flux of soluble, bioavailable Fe from aeolian dust.
31
Khalid, Muhammad, Faïçal Larachi e Alain Adnot. "Impact of silver sulphide on gold cyanidation with conductive sulphide minerals". Canadian Journal of Chemical Engineering 95, n. 10 (4 maggio 2017): 1875–84. http://dx.doi.org/10.1002/cjce.22870.
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Artemiev, Grigory, e Alexey Safonov. "Authigenic Mineral Formation in Aquifers near the Uranium Sludge Storage Facility of Chepetsky Mechanical Plant during the Formation of a Biogeochemical Barrier in a Laboratory and Field Experiment". Minerals 13, n. 10 (12 ottobre 2023): 1319. http://dx.doi.org/10.3390/min13101319.
Testo completoAbstract (sommario):
In this work, authigenic microbial mineral formation in groundwater near the uranium sludge storage at SC Chepetsky Mechanical Plant (ChMP) (Glazov, Russia) was analysed in field and laboratory experiments using thermodynamic modelling when the microbial community was activated by a mixture of acetate, glucose and whey. It was found that the mineral basis of the barrier consisted of aggregated soil particles with freshly deposited phases of carbonate and sulphide minerals of different degrees of crystallinity. An important factor in the formation of calcium phases is microbial denitrification, which is accompanied by an increase in pH values of the medium. The main factors of uranium immobilisation in the biogeochemical barrier were revealed, including its reduction to insoluble forms of uranium dioxide, adsorption on ferrous and sulphide-ferrous minerals, as well as the formation of phosphate phases through the addition of phosphorus-containing whey and co-precipitation or co-crystallisation in calcite phases.
33
Ball, T. K., J. R. Davies, R. A. Waters e J. A. Zalasiewicz. "Geochemical discrimination of Silurian mudstones according to depositional process and provenance within the Southern Welsh Basin". Geological Magazine 129, n. 5 (settembre 1992): 567–72. http://dx.doi.org/10.1017/s0016756800021725.
Testo completoAbstract (sommario):
AbstractA preliminary geochemical investigation of Silurian (Llandovery) basinal mudstones (turbidites and hemipelagites) from the Southern Welsh Basin is described. Turbidite mudstones show higher concentrations of Fe2O3, MgO, TiO2, MnO, LOI, Zn and Zr than laminated hemipelagites. This is consistent with the observed higher concentrations of chlorite and Ti-bearing minerals in turbidite mudstones. Laminated hemipelagites show higher values of REEs (Ce and La), concentrated within authigenic monazites, and Ni, As, Cu and Pb within sulphide minerals (pyrite and galena) reflecting the influence of primary organic carbon levels and anoxic bottom waters on early diagenesis. Deposition of hemipelagites under oxidizing conditions is reflected in lower concentrations of authigenic sulphide mineral hosted elements compared with laminated hemipelagic lithologies. There is a distinct geochemical difference between mudstones of easterly and southerly provenance in the Southern Welsh Basin. This is shown for both turbidites and hemipelagites. The differences are due to the increased input of illite and the chemical elements associated with this mineral (K2O, A12O3, Rb and Ba). Turbidite mudstones sourced from the south show increased levels of heavy minerals, especially those associated with Ti-rich minerals. There is also an increase in elements associated with detrital monazites: Th and Y. The hemipelagites show higher values of REE and chalcophile elements consistent with their more reduced nature.
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Tijsseling, Laurens T., Quentin Dehaine, Gavyn K. Rollinson e Hylke J. Glass. "Mineralogical Prediction of Flotation Performance for a Sediment-Hosted Copper–Cobalt Sulphide Ore". Minerals 10, n. 5 (23 maggio 2020): 474. http://dx.doi.org/10.3390/min10050474.
Testo completoAbstract (sommario):
As part of a study investigating the influence of mineralogical variability in a sediment hosted copper–cobalt deposit in the Democratic Republic of Congo on flotation performance, the flotation of nine sulphide ore samples was investigated through laboratory batch kinetics tests and quantitative mineral analyses. Using a range of ore samples from the same deposit the influence of mineralogy on flotation performance was studied. Characterisation of the samples through QEMSCAN showed that bornite, chalcopyrite, chalcocite and carrollite are the main copper-bearing sulphide minerals while carrollite is the only cobalt-bearing mineral. Mineralogical characteristics were averaged per sample to allow for a quantitative correlation with flotation performance parameters. Equilibrium recoveries, rate constants and final grades of the samples were correlated to the feed mineralogy through Multiple Linear Regression (MLR). Target sulphide minerals content and particle size, magnesiochlorite content, carrollite liberation and association of the copper and cobalt minerals with magnesiochlorite and dolomite were used to predict flotation performance. Leave One Out Cross Validation (LOOCV) revealed that the final copper and cobalt grades are predicted with an R2 of 0.80 and 0.93 and Root Mean Square Error of Cross Validation (RMSECV) of 4.41% and 1.34%. The recovery of cobalt and copper with time can be predicted with an R2 of 0.94 for both and an overall test error of 4.70% and 5.14%. Overall, it was shown that quantitative understanding of changes in mineralogy allows for prediction of changes in flotation performance.
35
Frater, Kenneth Maxwell. "Mineralization at the Golden Grove Cu – Zn deposit, Western Australia. II: Deformation textures of the opaque minerals". Canadian Journal of Earth Sciences 22, n. 1 (1 gennaio 1985): 15–26. http://dx.doi.org/10.1139/e85-002.
Testo completoAbstract (sommario):
Studies of the sulphide–magnetite fabric at Golden Grove. Western Australia, metamorphosed under conditions of lower to middle greenschist facies, indicate that pyrite and magnetite deformed in a brittle manner, whereas pyrrhotite, sphalerite, chalcopyrite, and galena deformed as ductile sulphides. In the accompanying silicate assemblage, pressure-solution deformation has been a significant deformation mechanism. An optical-microscope study of etched sphalerite reveals a wide range of microstructures indicative of ductile deformation, including lattice dislocations, subgrains and subboundaries, annealing twins, variable grain-boundary geometry, and recrystallization. The microstructures are distributed randomly through the sphalerite fabric and are similar to that formed during steady-state creep of deformed metals and that reported in dynamic recovery and recrystallization of deformed quartz. It is concluded that the ductile sulphides are modified by synkinematic recovery and recrystallization and that postkinematic recovery, annealing, and recrystallization, which are commonly reported for sulphide deposits, are not present.
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Watling, H. R. "The bioleaching of sulphide minerals with emphasis on copper sulphides — A review". Hydrometallurgy 84, n. 1-2 (ottobre 2006): 81–108. http://dx.doi.org/10.1016/j.hydromet.2006.05.001.
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Jaggar, S. R., e D. W. Emerson. "The effects of polarizable mineral type, amount, mix and grainsize in complex resistivity studies of synthetic mineralized sands". Exploration Geophysics 20, n. 2 (1989): 111. http://dx.doi.org/10.1071/eg989111.
Testo completoAbstract (sommario):
Controlled laboratory experiments were run using a computer controlled Solartron (1250A) Frequency Response Analyser coupled to very high impedance amplifiers at low current densities (2 � 10?2 Am?2) to obtain complex resistivity spectra in the 10 mHz to 10 kHz range from leached quartz sand (37?63 �m diam.) and granulated sulphide (63?1000 �m diam.) mixtures in four electrode cells saturated with brackish (80 Om, 20�C) and fresh 100 Om) chloride electrolyte. The sulphide particles and the silica background medium grains were angular in shape; the ratio of sulphide to sand size varied from 2:1 (63 �m tests) to 10:1 (710?1000 �m tests). The effects of mineral type, volume percent, grainsize, electrolyte resistivity, grainsize mix, and mineral mix were studied by means of spectral plots over 6 frequency decades, real-imaginary plots, and Cole?Cole parameter ridge regression inversions with up to three dispersions using an additive procedure. Hilbert transform checks on real and imaginary data components were made to monitor measurement linearity. The main crushed minerals studied were galena and chalcopyrite; sphalerite, pyrite, pyrrhotite, and graphite were also used. The test minerals (except for graphite) were not stoichiometric as varying, generally minor, amounts of other minerals (sulphide and silicates) were present in and on the grains; the chalcopyrite contained about 50% pyrite as intergrowths. The sand medium alone gave a flat resistivity and zero-phase spectrum to 2 kHz and thereafter presented a rapidly increasing phase attributed to dielectric polarization. Qualitatively the results showed: a distinct dependence of the critical frequency on grainsize and salinity with phase peaks shifting to lower frequencies with increasing grainsize and with increasing solution resistivities; phase peaks increasing in value and definition with increasing mineralisation in the 1 to 10% volume range; mixing of sulphide granizes broadening the phase curves, increasing the maximum values and shifting the peak responses; and no discernable dependence of magnitude or position of the phase peak with mineral types and on mineral mixes showedcertain phase effects that require additional experimental investigation before possibly useful or diagnostic responses might be identified. In the complex impendance plane the data plotted as depressed arcs at low to medium frequencies and the initial parts of further arcs were observed sometimes at high frequencies, suggesting kinetics limited charge-transfer and/or double layer controls on the polarizable minerals' interfacial reactions, rather than Warburg diffusion effects, at low to medium frequencies, and dielectric polarization at high frequencies. Quantitatively the inverted Cole?Cole m (chargeability), t (time constant), c(frequency dependence) parameters showed: m correlating with volume % polarizable minerals in the various grainsize ranges; m independent of or showing a slight decrease with increasing grainsize; t values varying from 5.2 � 10?6 to 9.5 � 10?3 seconds and relating poorly to volume % polarizable mineral but correlating directly to grainsize; and c values varying from 0.5 to 1.0 with most values occurring between 0.6 and 0.9 and higher c values correlating with lower t values. It is considered that synthetic mineral sand experiments readily provide data that may be interpreted empirically to study various mineral polarization effects, to test theorectical models of polarization behaviour, and to augment the sparse experimental IP data base.
38
Shen, Shuai Ping, Zhi Tao Yuan, Li Xia Li e Shuo Zhu. "Flotation Behavior of Jinchuan High Grade Copper-Nickel Sulphide with the Action of Different Regulators". Advanced Materials Research 826 (novembre 2013): 61–67. http://dx.doi.org/10.4028/www.scientific.net/amr.826.61.
Testo completoAbstract (sommario):
The useful minerals of Jinchuan high-grade copper and nickel suphfide ores were mainly nickel and copper, whose grade were respectively 1.42% and 1.01%. The content of MgO and SiO2, main gangue components, reached 57.89%. The key to improve the separation indexes of flotation concentrate was to inhibit the gangue minerals effectively, therefore, the effects of different kinds of regulators on Jinchuan high grade copper-nickel ores by flotation were studied. Considering the grade and recovery of concentrate comprehensively, the optimal regulator of mineral flotation was determined to be the combination of sodium hexametaphosphate and citric acid, and the dosage were 300g/t and 500g/t, respectively. After analyzing the mechanism of the two regulators, the combined reagents could reduce the isoelectric point of gangue minerals, decreasing the adsorption between gangue minerals and valuable minerals. In addition, the reagents were able to eliminate the activation of useless ions such as Ca2+ and Ni2+ on the gangue minerals and improve the ion composition of pulp, increasing the difference of floatability between gangue and useful minerals.
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Wang, Yan, Zhongwei Wu, Xiaoming Sun, Xiguang Deng, Yao Guan, Li Xu, Yi Huang e Kaijun Cao. "He–Ar–S Isotopic Compositions of Polymetallic Sulphides from Hydrothermal Vent Fields along the Ultraslow-Spreading Southwest Indian Ridge and Their Geological Implications". Minerals 8, n. 11 (7 novembre 2018): 512. http://dx.doi.org/10.3390/min8110512.
Testo completoAbstract (sommario):
Noble gases have become a powerful tool to constrain the origin and evolution of ore-forming fluids in seafloor hydrothermal systems. The aim of this study was to apply these tracers to understand the genesis of newly discovered polymetallic sulphide deposits along the ultraslow-spreading Southwest Indian Ridge (SWIR). The helium, argon, and sulphur isotope compositions of metal sulphide minerals were measured for a number of active/inactive vent fields in the Indian Ocean. The helium concentrations and isotopic ratios in these ore samples are variable (4He: 0.09–2.42 × 10−8 cm3STP∙g−1; 3He: 0.06–3.28 × 10−13 cm3STP∙g−1; 3He/4He: 1.12–9.67 Ra) and generally greater than the modern atmosphere, but significantly lower than those in massive sulphides from the fast-spreading East Pacific Rise (EPR), especially for three Cu–Fe-rich samples from the ultramafic-hosted Tianzuo and Kairei vent fields. On the contrary, most of the SWIR sulphide deposits have somewhat higher 40Ar/36Ar ratios of trapped fluids (ranging from 290.6 to 303.4) when compared to the EPR ore samples. Moreover, the majority of sulphide minerals from the Indian Ocean have much higher δ34S values (3.0‰–9.8‰, ~5.9 on average, n = 49) than other basaltic-hosted active hydrothermal systems on the EPR. Overall, these He–Ar–S results are well within the range of seafloor massive sulphide deposits at global sediment-starved mid-ocean ridges (MORs), lying between those of air-saturated water (ASW) and mid-ocean ridge basalt (MORB) end members. Therefore, our study suggests that the helium was derived mainly from the MORB mantle by degassing during the high-temperature stage of hydrothermal activity, as well as from a mixture of vent fluids with variable amounts of ambient seawater during either earlier or late-stage low-temperature hydrothermal episodes, whereas the argon in ore-forming fluids trapped within sulphide minerals was predominantly derived from deep-sea water. Additionally, relatively high δ34S values exhibit a great estimated proportion (up to nearly 40%) of seawater-derived components. In summary, sub-seafloor extensive fluid circulation, pervasive low-temperature alteration, shallow seawater entrainment, and mixing processes, may make a larger contribution to the SWIR hydrothermal ore-forming systems, compared to fast-spreading centres.
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Koomson, Bennetta, Shadrack Fosu, Blestmond Afrifa Brako, Elias Kwasi Asiam e Ernest K. Yanful. "ASSESSING THE ACID MINE DRAINAGE POTENTIAL OF A STOCKPILED GOLD BEARING SULPHIDE ORE". Earth Science Malaysia 5, n. 1 (29 dicembre 2020): 58–64. http://dx.doi.org/10.26480/esmy.01.2021.58.64.
Testo completoAbstract (sommario):
This work seeks to assess the acid mine drainage (AMD) potential of stockpiled sulphidic gold bearing ore that was left untreated for a period of four (4) years. The mineralogical composition of the stockpiled sulphidic gold ore was determined using X-Ray Diffractometry (XRD) and Reflected Light Microscope. The AMD potential and kinetic studies on the ore sample were determined using Acid Base Accounting (ABA) and Humidity Cell (ASTMD 5744). The XRD and microscope analyses showed that the gold ore contain arsenopyrite and pyrite as the major sulphide minerals. The ABA confirmed that the gold sulphide ore could be a potential source of AMD with respect to AMD marginal of safety if the ore is left untreated for a very long period. Humidity Cell kinetic analysis showed a possibility of mobilizing Arsenic (As) into the geo-environment when there is a long period of oxidation of abandoned sulphide run-of-mine (ROM) ore.
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Africa, C. J., Robert P. van Hille e Susan T. L. Harrison. "Investigation and Visualisation of Microbial Attachment Trends to Sulphide Minerals in a Bioleach Environment". Advanced Materials Research 71-73 (maggio 2009): 345–48. http://dx.doi.org/10.4028/www.scientific.net/amr.71-73.345.
Testo completoAbstract (sommario):
Two novel experimental approaches have been developed to investigate the attachment of microorganisms to sulphide minerals as a function of the mineral and microbial phase in a joint project with BHP Billiton, conceptualised in 2005 and initiated in 2006. In the first approach, selective attachment of pure cultures to minerals was studied in the “particle coated column reactor” using A. ferrooxidans and L. ferriphilum. The saturated reactor containing glass beads coated with fine mineral concentrates provided a quantifiable surface area of mineral concentrate and maintained good fluid flow. Results are reported for chalcopyrite and pyrite concentrates, a low grade chalcopyrite ore and quartzite. The latter, representing typical gangue material, is used as a control. A. ferrooxidans displayed greater attachment to pyrite, and selective attachment to sulfide minerals over quartz. Similar attachment behaviour trends resulted for Leptospirillum spp. In the second approach, a novel technique was developed to investigate microbial ecology of microbe-mineral attachment, site and mineral specific associations of microorganisms and spatial organisation of microbial communities present. Qualitative assessment and visualisation of microorganisms associated with the mineral surface and subsequent biofilm development was shown in the biofilm reactor, using microscopy techniques and fluorochromes. FISH analyses of A. ferrooxidans and L. ferriphilum on massive chalcopyrite sections are presented. The consequence of the observed attachment on heap bioleach performance is discussed.
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Kotzé, E., e C. Gauert. "PGE distribution in the chromitite layers at Eastern Chrome Mine, Eastern Bushveld Complex, South Africa: A descriptive study with comparison of EPMA and LA-ICP-MS methods for detection of trace PGE in base metal sulphides". South African Journal of Geology 123, n. 4 (26 ottobre 2020): 551–72. http://dx.doi.org/10.25131/sajg.123.0033.
Testo completoAbstract (sommario):
Abstract A descriptive petrographic study was carried out on the chromitites (LG-6 to UG-3a) of a single borehole from the Winterveld Chrome Mine, Eastern BC, along with analysis by both EPMA and LA-ICP-MS of the PGE contents of base metal sulphides (BMS) found within these layers. EPMA measurements were optimized to measure trace amounts of PGE by increased probe current and counting time, yielding very low detection limits for this method (12 to 38 ppm). However, analytical error proved to be very high (over ~30%) in samples that showed PGE values below 100 ppm. Also, the possibility of interference on PGE spectra by other elements, especially on Rh, is high. Therefore, these measurements can only be considered semi-quantitative indicators of elemental PGE concentration. Our findings confirmed that pentlandite of the BC chromitites contains Pd and Rh, probably in solid solution. Pt was found in discrete minerals (braggite, cooperite) throughout the sequence, and Ru, Ir and Os were found as early-stage minerals such as laurite, associated with chromite rather than sulphide. The PPGE increase upwards in the chromitite layers relative to the IPGE. An immiscible sulphide phase contributed to collection of the PGE in the chromitites of the MG-4 and above. The chromitites of the LG-6 to MG-1 show less evidence of hosting an immiscible sulphide phase, and pentlandite of these layers does not appear to host Rh, although Pd was found. Although this borehole is located only 1.5 km away from the centre of the Steelpoort Fault Zone, a possible feeder zone for the BC, large-scale disruption of the chromitite layers was not observed. An intrusive pegmatoidal pyroxenite was found to occur beneath the LG-6, and contained PGE-bearing sulphides, although the origin of this mineralization is most likely from the LG-6 chromitite itself. A sulphide vein occurring in silicate was also analysed and was found to be PGE-deficient compared to the sulphides of the chromitite layers.
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Duckworth, Rowena C., e David Rickard. "Sulphide mylonites from the Renström VMS deposit, Northern Sweden". Mineralogical Magazine 57, n. 386 (marzo 1993): 83–91. http://dx.doi.org/10.1180/minmag.1993.057.386.08.
Testo completoAbstract (sommario):
AbstractSulphide mylonites are fine-grained massive sulphides which have deformed in a plastic manner. In the Renström Zn-Pb-Cu-Ag-Au VMS deposit, one of several operating mines in the Early Proterozoic Skellefte District in Northern Sweden, shear-zone metamorphism has resulted in the development of mylonitic fabrics within the sulphides. The massive sulphide ore is hosted in a shallow submarine to subaerial volcano-sedimentary sequence which has been variably metamorphosed and deformed. Initially, the sequence underwent burial metamorphism which was followed by an amphibolite grade regional metamorphic event at pressures of around 7.5 kbar and temperatures of 540-600°C This has been overprinted by a retrogressive metamorphic event at greenschist facies (at ca. 400°C with concomitant ductile deformation. Finally the area was uplifted to shallower crustal levels with associated cataclastic deformation.Both the regional and dynamic metamorphic events have resulted in the development of specific textures in the sulphide ores. Textural evidence indicates that pressure solution has been mainly responsible for the plastic deformation in pyrite, while the weaker sulphide minerals such as pyrrhotite, chalcopyrite and galena have generally recrystallised in response to the high strains.Sulphide mylonites are probably common rocks in many polydeformed massive sulphide deposits like Renström. They may have previously been misinterpreted as primary depositional textures.
44
Tribovillard, Nicolas, Olivier Averbuch, Anne Bialkowski e Jean-François Deconinck. "Early diagenesis of marine organic-matter and magnetic properties of sedimentary rocks: the role of iron limitation and organic-matter source organisms". Bulletin de la Société Géologique de France 173, n. 4 (1 luglio 2002): 295–306. http://dx.doi.org/10.2113/173.4.295.
Testo completoAbstract (sommario):
Abstract The magnetic parameters of sedimentary rocks can record accurately tectonic and climatic influences upon sedimentary processes, when they are not altered during diagenesis. This paper is focused on the possible alteration of the primary magnetic-susceptibility signal during early diagenesis of marine organic matter (OM). In the late Kimmeridgian-Tithonian Argiles de Châtillon Formation (Fm.) of the Boulonnais area (northern France – lateral time equivalent of the distal organic-rich sediments of the Kimmeridge Clay Fm. of Dorset), the organic content is dominated by amorphous OM (AOM), either brown or orange, originating from selective preservation or sulphurisation, respectively. Total sulphur content correlates well with orange + brown AOM abundance, and organic S content correlates well with orange AOM abundance. The magnetic signal of these claystones and paper shales is dominantly carried by clay minerals. The magnetic susceptibility vs. brown-AOM abundance relationship shows a clear correlation. Furthermore, if the part of the magnetic-susceptibility signal linked to the lithoclastic fraction of the sediments is removed from the total signal, a positive correlation is also drawn between the brown-AOM abundance and the ‘excess’ magnetic susceptibility. The cause for this resides in the iron-sulphide abundance. The presence of both types of AOM implies that intense sulphate reduction took place and that the HS−/H2S released reacted with either organic molecules (orange AOM dominating the palynofacies) or reactive iron (brown AOM dominating). When reactive iron was abundant enough and when sulphate reduction-induced sulphide ions could react with it, iron sulphides could form and this sediment component (present now as pyrite) influences the magnetic-susceptibility signal. The type of dominating source organisms (phytoplankton) may condition the reactivity of OM towards sulphide ions. This may influence iron-sulphide formation, and in turn the sediment magnetic signal.
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Sokic, Miroslav, Jovica Stojanovic, Branislav Markovic, Mladen Bugarcic, Nada Strbac, Zeljko Kamberovic e Vaso Manojlovic. "Effects of structural and textural grain characteristics on leaching of sulphide minerals from a polymetallic concentrate by sodium nitrate and sulphuric acid solution". Chemical Industry 71, n. 6 (2017): 461–69. http://dx.doi.org/10.2298/hemind161130006s.
Testo completoAbstract (sommario):
In this paper, the influence of structural and textural characteristics of sulfide minerals on their leaching from a polymetallic concentrate by sulfuric acid and sodium nitrate solution is presented. The starting material was Pb?Zn?Cu sulphide polymetallic concentrate enriched during the flotation of a polymetallic ore in the "Rudnik" flotation plant (Rudnik ? Serbia). Leaching experiments were carried out in a closed glass reactor, which provides stable hermetic conditions and allows heating at constant temperature. Chemical, XRD, qualitative and quantitative microscopic and SEM/EDX analyses were used to characterizes samples of the polymetallic concentrate and leach residue. It was determined that chalcopyrite, sphalerite, galena, pyrrhotite and quartz were present in the polymetallic concentrate. The content of sulphide minerals was 69.5%, of which 60.9% occurred as liberated grains: 88.3% of chalcopyrite, 59.3% of sphalerite, 25.1% of galena and 51.6% of pirrhotite. The rest of chalcopyrite, sphalerite, galena and pirrhotite grains were in the forms of inclusions, impregnations, and simple and complex intergrowths. During the leaching process by sodium nitrate and sulphuric acid solution, it was shown previously that the leaching rate of sulphide minerals decreased with time while a part of the sulphide minerals remained in the leach residue. After leaching at 80?C for 120 min, the yields were 69.8, 82.7 and 67.1% for Cu, Zn and Fe, respectively. Lead, in the form of insoluble anglesite, remained in the leach residue. In addition to the anglesite, unleached sulfide minerals and quartz, elemental sulfur was found in the solid residue. The content of sulphide minerals was 35% of which 33.7% minerals occur independently. In specific, 54.7% of chalcopyrite, 31.9% of sphalerite, 8.2% of galena and 37.6% of pyrrhotite appear as separate grains with highly corroded surfaces. Therefore, the structural assembly of sulphide grains in the polymetallic concentrate is favourable and it is not the reason for the observed decrease in the leaching rate in the final process stages. The obtained findings may be explained by the presence of elemental sulphur that is formed during the reaction and precipitated at the grain surfaces, thus creating a diffusion barrier for the leach solution.
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Harris, D. L., e B. G. Lottermoser. "Phosphate stabilization of polyminerallic mine wastes". Mineralogical Magazine 70, n. 1 (febbraio 2006): 1–13. http://dx.doi.org/10.1180/0026461067010309.
Testo completoAbstract (sommario):
AbstractPolyminerallic, sulphidic mine wastes were treated with KH2PO4-H2O2 solutions to determine whether the formation of solid phosphate coatings inhibits sulphide oxidation and metal and metalloid mobility. The waste rocks were metal (PbZnCu) and metalloid (AsSb) rich and consisted of major quartz, dickite, illite and sulphide minerals (e.g. galena, chalcopyrite, tetrahedrite, sphalerite, pyrite, arsenopyrite) as well as minor to trace amounts of pre- and post-mining oxidation products (e.g. oxides, hydroxides, arsenates and sulphates). Scanning electron microscopy observations of the waste material treated with KH2PO4-H2O2 solutions showed that metal, metal-alkali and alkali phosphate precipitates formed and coatings developed on all sulphides (with the exception of tetrahedrite). The abundance of phosphate phases was dependant on the availability of metal and alkali cations in solution. In turn, the release of cations was dependent on the amount of sulphide oxidation induced during the experiment or the presence of soluble oxidation products. Lead and to a lesser degree Cu and Zn phosphate coatings remained stable during H2O2 leaching, preventing acid generation and metal release. In contrast, the lack of phosphate coating on tetrahedrite and arsenopyrite allowed oxidation and leaching of As and Sb to proceed and mobilized As and Sb did not form phosphate phases. As a result, As and Sb displayed the greatest release from the coated waste. Thus, the application of KH2PO4-H2O2 solutions to partly oxidized, polyminerallic mine wastes suppresses sulphide oxidation and is most effective in inhibiting Pb (Cu and Zn) release. However, the technique appears ineffective in preventing metalloid (As, Sb) leaching from tetrahedrite- and arsenopyrite-bearing wastes.
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Tabatabaei, Reyhaneh H., D. R. Nagaraj, Sergio M. S. M. Vianna, Timothy J. Napier-Munn e Barun Gorain. "The effect of non-sulphide gangue minerals on the flotation of sulphide minerals from Carlin-type gold ores". Minerals Engineering 60 (giugno 2014): 26–32. http://dx.doi.org/10.1016/j.mineng.2014.02.004.
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