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1
Knobloch, Marjan, and Bernd G. Lottermoser. "Infrared Thermography: A Method to Visualise and Analyse Sulphide Oxidation." Minerals 10, no. 11 (October 22, 2020): 933. http://dx.doi.org/10.3390/min10110933.
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Environmental testing of sulphidic ores and wastes aims to assess the release of metals and metalloids at acid pH conditions and the samples’ likelihood to produce acid rock drainage (ARD). However, the majority of established ARD tests measure geochemical properties of samples and cannot visualise the exothermic oxidation reactions and their intensity leading to metalliferous drainage in all pH environments. This paper proposes a new protocol to detect and visualise the sulphide oxidation in ores and wastes. Six nearly monomineralic sulphides were crushed, sieved to two size fraction (0.09–4 mm), milled to powder and treated with H2O2. The thermal energy released upon sulphide oxidation was optically detected and temperatures measured using a portable infrared thermographic camera. Based on temperature–time progression curves, the oxidation reactivity of sulphides was derived from high to low: chalcopyrite > arsenopyrite > pyrite > sphalerite > stibnite > galena, which depends on grain size, amount of sulphides and other non-sulphide mineral phases present in the sample material. The study demonstrates that the application of H2O2 to sulphide sample powders and subsequent visualisation of the treated materials using a thermographic camera represents a rapid technique in revealing the presence of oxidising sulphides under all pH conditions.
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Barnes, Sarah-Jane, and A. J. Naldrett. "Variations in platinum group element concentrations in the Alexo mine komatiite, Abitibi greenstone belt, northern Ontario." Geological Magazine 123, no. 5 (September 1986): 515–24. http://dx.doi.org/10.1017/s001675680003510x.
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AbstractThe noble element (Os, Ir, Ru, Rh, Pt, Pd, Au) patterns from sulphides associated with the komatiites at the Alexo mine show variable degrees of fractionation. Massive sulphides at the contact between underlying intermediate volcanics and overlying komatiites have the least fractionated patterns (Pd/Ir = 44). Net-textured sulphides which immediately overlie the massive sulphides have extremely fractionated noble element patterns (Pd/Ir = 171). The disseminated sulphides in the overlying komatiite exhibit an intermediate degree of fractionation (Pd/Ir = 110). The variations in noble element patterns are complemented by variations in the Ni, Cu and Co concentrations. The massive sulphides are depleted in all three of these elements relative to the net-textured sulphide ore. The disseminated sulphides have intermediate values of Ni and Co, but are enriched in Cu relative to the other two sulphides.Processes that could have affected the composition of the sulphides include: (a) fractionation of monosulphide solid solution (Mss) from a sulphide liquid during initial cooling of the komatiite, and (b) mobilization of Pt, Pd, Au, Cu, Ni and Co from the massive sulphide into footwall veins. A mass balance calculation indicates that the sum of the massive and net-textured sulphide agrees with the disseminated sulphide for all elements except Au. Thus the massive sulphide cannot have lost significant amounts of Pt, Pd, Ni and Co to footwall veins and significant mobilization of these elements does not appear to have occurred. The crystallization of Mss from a sulphide liquid will account for the enrichment of Ir, Os, Ru and Rh in the massive sulphide relative to the net-textured sulphide, and enrichment of Pd, Pt, Au, Co and Ni in the net-textured sulphide relative to the disseminated sulphide.
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Barnes, Sarah-Jane, M. L. Zientek, and M. J. Severson. "Ni, Cu, Au, and platinum-group element contents of sulphides associated with intraplate magmatism: a synthesis." Canadian Journal of Earth Sciences 34, no. 4 (April 1, 1997): 337–51. http://dx.doi.org/10.1139/e17-030.
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The tectonic setting of intraplate magmas, typically a plume intersecting a rift, is ideal for the development of Ni – Cu – platinum-group element-bearing sulphides. The plume transports metal-rich magmas close to the mantle–crust boundary. The interaction of the rift and plume permits rapid transport of the magma into the crust, thus ensuring that no sulphides are lost from the magma en route to the crust. The rift may contain sediments which could provide the sulphur necessary to bring about sulphide saturation in the magmas. The plume provides large volumes of mafic magma; thus any sulphides that form can collect metals from a large volume of magma and consequently the sulphides will be metal rich. The large volume of magma provides sufficient heat to release large quantities of S from the crust, thus providing sufficient S to form a large sulphide deposit. The composition of the sulphides varies on a number of scales: (i) there is a variation between geographic areas, in which sulphides from the Noril'sk–Talnakh area are the richest in metals and those from the Muskox intrusion are poorest in metals; (ii) there is a variation between textural types of sulphides, in which disseminated sulphides are generally richer in metals than the associated massive and matrix sulphides; and (iii) the massive and matrix sulphides show a much wider range of compositions than the disseminated sulphides, and on the basis of their Ni/Cu ratio the massive and matrix sulphides can be divided into Cu rich and Fe rich. The Cu-rich sulphides are also enriched in Pt, Pd, and Au; in contrast, the Fe-rich sulphides are enriched in Fe, Os, Ir, Ru, and Rh. Nickel concentrations are similar in both. Differences in the composition between the sulphides from different areas may be attributed to a combination of differences in composition of the silicate magma from which the sulphides segregated and differences in the ratio of silicate to sulphide liquid (R factors). The higher metal content of the disseminated sulphides relative to the massive and matrix sulphides may be due to the fact that the disseminated sulphides equilibrated with a larger volume of magma than massive and matrix sulphides. The difference in composition between the Cu- and Fe-rich sulphides may be the result of the fractional crystallization of monosulphide solid solution from a sulphide liquid, with the Cu-rich sulphides representing the liquid and the Fe-rich sulphides representing the cumulate.
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Smith, W. D., W. D. Maier, and I. Bliss. "Contact-style magmatic sulphide mineralisation in the Labrador Trough, northern Quebec, Canada: implications for regional prospectivity." Canadian Journal of Earth Sciences 57, no. 7 (July 2020): 867–83. http://dx.doi.org/10.1139/cjes-2019-0137.
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The Labrador Trough in northern Quebec is currently the focus of ongoing exploration for magmatic Ni-Cu-platinum group element (PGE) sulphide ores. This geological belt hosts voluminous basaltic sills and lavas of the Montagnais Sill Complex, which are locally emplaced among sulphidic metasedimentary country rocks. The recently discovered Idefix PGE-Cu prospect represents a stack of gabbroic sills that host stratiform patchy disseminated to net-textured sulphides (0.2–0.4 g/t PGE+Au) over a thickness of ∼20 m, for up to 7 km. In addition, globular sulphides occur at the base of the sill, adjacent to the metasedimentary floor rocks. Whole-rock and PGE geochemistry indicates that the sills share a common source and that the extracted magma underwent significant fractionation before emplacement in the upper crust. To develop the PGE-enriched ores, sulphide melt saturation was attained before final emplacement, peaking at R factors of ∼10 000. Globular sulphides entrained along the base of the sill ingested crustally derived arsenic and were ultimately preserved in the advancing chilled margin.
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Ofori-Sarpong, G., D. K. Adjei, and R. K. Amankwah. "Fungal-Transformation of Surrogate Sulphides and Carbonaceous Matter in Refractory Gold Ores: Revisited." Ghana Mining Journal 17, no. 2 (December 13, 2017): 56–65. http://dx.doi.org/10.4314/gm.v17i2.8.
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In the recovery of gold from refractory gold ores, pretreatment is required to decompose sulphides and liberate occluded gold before cyanidation, and to deactivate carbonaceous matter and prevent it from adsorbing dissolved gold. Until the past three decades, most commercial pretreatment processes had been by abiotic means. Biological pretreatment methods on commercial basis is therefore a recent phenomenon, and several researches are underway to assess the ability of different biological agents in the breakdown of sulphur and carbonaceous matter (CM) in gold ores. This paper, which is a revisit of an earlier one, presents an overview of on-going research aimed at assessing the capability of the fungus, Phanerochaete chrysosporium, to degrade sulphides and CM. Surrogate carbonaceous materials (lignite, bituminous and anthracite coals) and pure sulphides (pyrite and arsenopyrite) were used to model the behavior of CM and sulphides in refractory gold ores. To monitor the extent of biotransformation, preg-robbing test was conducted on the as-received and treated CM, and sulphide sulphur in the residual sulphidic materials was also determined. From an initial preg-robbing effect of 125 µg of gold per gram of CM, the ability of CM to preg-rob gold reduced by 70-95% in the order of lignite<bituminous <anthracite within 21 days of treatment, whereas there were 18% and 39% oxidation of sulphide sulphur in pyrite and arsenopyrite respectively. XRD examination of the treated anthracite confirmed reduction in the graphitic structure of carbon following fungal transformation. Similarly, there was a decline in the major sulphide peak after microbial pretreatment. The results indicate that the fungus biotransforms through destruction of the ordered structure, followed by introduction of oxygen groups. The amorphous nature, thus generated, inhibits the uptake of aurocyanide ions by CM, while enhancing the affinity of cyanide for the oxidised sulphide material in subsequent cyanidation treatment. The findings contribute to knowledge on novel and technically viable alternative methods for oxidative pretreatment of refractory gold ores. Keywords: Phanerochaete Chrysosporium, Carbonaceous Matter, Metal Sulphides, Biotransformation
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Smyk, Mark C., and David H. Watkinson. "Sulphide remobilization in Archean volcano-sedimentary rocks and its significance in Proterozoic silver vein genesis, Cobalt, Ontario." Canadian Journal of Earth Sciences 27, no. 9 (September 1, 1990): 1170–81. http://dx.doi.org/10.1139/e90-124.
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The Archean volcano-sedimentary succession at Cobalt, Ontario, consists mainly of submarine andesitic flows and turbiditic interflow sedimentary rocks. Steeply dipping faults and large-scale, tight to isoclinar folds have developed in these basement rocks. The faults commonly host silver-vein-bearing structures that extend upward into overlying Proterozoic units. Synvolcanic and synsedimentary base metal sulphide deposits are ubiquitous in the Archean rocks. Epigenetic sulphide mineralization consists of remobilized and replacement sulphides and minor sulpharsenides. Epigenetic sulphides occur in permeable rocks and in fault and fracture zones, commonly in juxtaposition with silver veins.The coincidence of silver veins and structures containing remobilized sulphides suggests that sulphide remobilization from Archean basement rocks into Proterozoic vein-bearing structures predated or accompanied vein development. Sulphide remobilization may have also facilitated the mobilization (leaching) of metals from basement sulphides into the vein-forming hydrothermal fluids.
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Lutnicki, Krzysztof, Eligiusz Madej, Tomasz Riha, and Łukasz Kurek. "Polioencephalomalacia in ruminants caused by excessive amount of sulphur - a review." Bulletin of the Veterinary Institute in Pulawy 58, no. 2 (June 1, 2014): 321–26. http://dx.doi.org/10.2478/bvip-2014-0050.
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Abstract Polioencephalomalacia as a result of sulphur excess is a growing problem in cattle and sheep, mainly in young, growing animals. It is common in different regions of the world. The disease develops favoured by certain conditions such as sustained provision of feed and water with high sulphur content, use of dietary supplements containing sulphur, and a habitat with high hydrogen sulphide concentration. Pathogenesis of the disease is complex, but very important are oxidative-antioxidative imbalance, dysfunction of vessels, and secondary cerebral cortex ischaemia as a result of direct and/or indirect action of sulphur metabolites, namely hydrogen sulphide, sulphides, and sulphites. Clinical signs and changes in the cerebral cortex in the form of degenerative necrotic lesions are similar to those observed in polioencephalomalacia caused by vitamin B1 deficiency, and lead and salt intoxication. Highly increased sulphur content (more than 0.3-0.4 of dry matter) in the diet is the basis for differential diagnosis, as well the high concentration of hydrogen sulphide in gas and sulphides in rumen fluid. In prophylaxis and treatment the most important measure is to limit sulphur intake and in acute cases to neutralise low pH in rumen and administer vitamin B1 injections.
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Edwards, Grant A., Phillip A. Culp, and Justin M. Chalker. "Allyl sulphides in olefin metathesis: catalyst considerations and traceless promotion of ring-closing metathesis." Chemical Communications 51, no. 3 (2015): 515–18. http://dx.doi.org/10.1039/c4cc07932a.
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Allyl sulphides provoke rapid olefin metathesis when matched with an appropriate catalyst. In relay metathesis, allyl sulphides can serve as traceless promoters that facilitate the synthesis of non-sulphide targets.
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DEMARIGNY, YANN, CÉLINE BERGER, NATHALIE DESMASURES, MICHELINE GUEGUEN, and HENRY E. SPINNLER. "Flavour sulphides are produced from methionine by two different pathways by Geotrichum candidum." Journal of Dairy Research 67, no. 3 (August 2000): 371–80. http://dx.doi.org/10.1017/s0022029900004209.
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We have investigated the capacities of Geotrichum candidum strains to produce sulphides from methionine. This attribute is very important in cheese technology because of the flavouring potential of sulphur compounds. A spectrophotometric procedure using 5,5′-dithiobis(2-nitrobenzoic acid) to determine sulphides was tested on a collection of G. candidum strains, and confirmed by gas chromatography–mass spectrometry. The strains were distinguished on the basis of their ability to produce methanethiol. Gas chromatography–mass spectrometry also made it possible to identify other sulphides, such as dimethyl disulphide, dimethyl trisulphide and dimethyl sulphide. Using sonicated cells, the specific production of these four sulphides was studied in presence of L-[S-methyl-2H]methionine. Both methanethiol and dimethyl sulphide were produced from methionine, but two different pathways were used by G. candidum.
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Luptakova, Alena, and E. Macingova. "Sorption of Copper Ions by Biogenic Iron Sulphides." Advanced Materials Research 20-21 (July 2007): 631–34. http://dx.doi.org/10.4028/www.scientific.net/amr.20-21.631.
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Biogenic iron sulphides are excellent adsorbents for various heavy metals ions. Consequently, they have practical application for the elimination of heavy metals from waste waters. One of the principles for the iron sulphides preparation is the application of sulphatereducing bacteria. This biological-chemical method is based on the ability of these bacteria to reduce sulphates to hydrogen sulphide, which binds with the ferrous cations to form insoluble precipitates – iron sulphides. Under certain bacterial growth conditions biogenic iron sulphides can be magnetic. The aim of this work is to study the possibility of using SRB for the preparation of iron sulphides, which were used subsequently in the framework of sorption tests to eliminate copper ions from model solutions.
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Nowińska, Katarzyna, and Zdzisław Adamczyk. "Chemical composition of iron sulphides contained in dust from pyrometallurgical Zn and Pb production." Geochemistry: Exploration, Environment, Analysis 21, no. 2 (April 12, 2021): geochem2020–073. http://dx.doi.org/10.1144/geochem2020-073.
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The paper presents results of investigations of the chemical composition of iron sulphides contained in dust from the pyrometallurgical production process of zinc and lead. The main mineral components of these dusts are sphalerite, galena, iron sulphide – pyrite, zincite, anglesite and probably kirchsteinite. The tests performed have demonstrated that the chemical composition of iron sulphide grains was not close to stoichiometric, the grains were non-uniform in terms of phase composition and they always included admixtures in the form of inclusions of other sulphides, i.e. zinc sulphide and lead sulphide, and accompanying elements (Ca, Mn, Se, As, Ag, Cu, Cd).
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Prokkola, Hanna, Emma-Tuulia Nurmesniemi, and Ulla Lassi. "Removal of Metals by Sulphide Precipitation Using Na2S and HS−-Solution." ChemEngineering 4, no. 3 (September 4, 2020): 51. http://dx.doi.org/10.3390/chemengineering4030051.
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Precipitation of metals as metal sulphides is a practical way to recover metals from mine water. Sulphide precipitation is useful since many metals are very sparingly soluble as sulphides. Precipitation is also pH dependent. This article investigates the precipitation of metals individually as sulphides and assesses which metals are precipitated as metal hydroxides by adjustment of the pH. The precipitation of different metals as sulphides was studied to determine the conditions under which the HS− solution from the sulphate reduction reaction could be used for precipitation. H2S gas and ionic HS− produced during anaerobic treatment could be recycled from the process to precipitate metals in acidic mine drainage (AMD) prior to anaerobic treatment (Biological sulphate reduction), thereby recovering several metals. Precipitation of metals with HS− was fast and produced fine precipitates. The pH of acid mine water is about 2–4, and it can be adjusted to pH 5.5 before sulphide precipitation, while the precipitation, on the other hand, requires a sulphide solution with pH at 8 and the sulphide in HS− form. This prevents H2S formation and mitigates the risk posed from the evaporation of toxic hydrogen sulphur gas. This is a lower increase than is required for hydroxide precipitation, in which pH is typically raised to approximately nine. After precipitation, metal concentrations ranged from 1 to 30 μg/L.
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Zhang, Hongyu, and Yunqian Cui. "Study of Sulphides Production Affecting the Fermentation Process of the Lager Beer." International Journal of Biology and Life Sciences 3, no. 1 (May 20, 2023): 4–8. http://dx.doi.org/10.54097/ijbls.v3i1.9481.
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In the lager brewing production process, volatile sulphides such as sulphur dioxide, hydrogen sulphide, thiols and thioesters are produced by yeast metabolism during the fermentation of lager beer. Fluctuations in malt raw materials, yeast strain characteristics and fermentation process parameter adjustments can all have an impact on sulphides, and the concentration of sulphides in finished beer can have a negative impact on the sensory tasting of lager beer. This study investigated the fermentation of sulphides in lager beer under the conditions of dissolved wort oxygen, yeast recovery, fermentation temperature and pressure, and the results showed that the longer the yeast growth time, the later the fermentation of sulphur dioxide and the lower the sulphur dioxide content in the final beer by 10mg/L. The longer the yeast recovery days, the higher the fermentation of sulphur dioxide and hydrogen sulphide. The higher the content, the higher the fermentation temperature of the lager and the faster the fermentation rate, which favours a low sulphur dioxide content at the end of the main fermentation.
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Eliopoulos, Demetrios G., Maria Economou-Eliopoulos, George Economou, and Vassilis Skounakis. "Mineralogical and Geochemical Constraints on the Origin of Mafic–Ultramafic-Hosted Sulphides: The Pindos Ophiolite Complex." Minerals 10, no. 5 (May 18, 2020): 454. http://dx.doi.org/10.3390/min10050454.
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Sulphide ores hosted in deeper parts of ophiolite complexes may be related to either primary magmatic processes or links to hydrothermal alteration and metal remobilization into hydrothermal systems. The Pindos ophiolite complex was selected for the present study because it hosts both Cyprus-type sulphides (Kondro Hill) and Fe–Cu–Co–Zn sulphides associated with magnetite (Perivoli-Tsoumes) within gabbro, close to its tectonic contact with serpentinized harzburgite, and thus offers the opportunity to delineate constraints controlling their origin. Massive Cyprus-type sulphides characterized by relatively high Zn, Se, Au, Mo, Hg, and Sb content are composed of pyrite, chalcopyrite, bornite, and in lesser amounts covellite, siegenite, sphalerite, selenide-clausthalite, telluride-melonite, and occasionally tennantite–tetrahedrite. Massive Fe–Cu–Co–Zn-type sulphides associated with magnetite occur in a matrix of calcite and an unknown (Fe,Mg) silicate, resembling Mg–hisingerite within a deformed/metamorphosed ophiolite zone. The texture and mineralogical characteristics of this sulphide-magnetite ore suggest formation during a multistage evolution of the ophiolite complex. Sulphides (pyrrhotite, chalcopyrite, bornite, and sphalerite) associated with magnetite, at deeper parts of the Pindos (Tsoumes), exhibit relatively high Cu/(Cu + Ni) and Pt/(Pt + Pd), and low Ni/Co ratios, suggesting either no magmatic origin or a complete transformation of a preexisting magmatic assemblages. Differences recorded in the geochemical characteristics, such as higher Zn, Se, Mo, Au, Ag, Hg, and Sb and lower Ni contents in the Pindos compared to the Othrys sulphides, may reflect inheritance of a primary magmatic signature.
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Santagulda, F., and M. D. Hannington. "Characteristics of gold mineralization in volcanogenic massive sulphide deposits of the Notre Dame Bay area, central Newfoundland." Canadian Journal of Earth Sciences 33, no. 2 (February 1, 1996): 316–34. http://dx.doi.org/10.1139/e96-024.
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A reconnaissance study of 19 volcanogenic massive sulphide deposits in the Notre Dame Bay area indicates Au concentrations of up to 30 ppm (Betts Cove), and elevated gold contents (>1 ppm Au) have been found in samples from 10 additional past producers and developed prospects. Systematic trends in the occurrence of gold are observed in two principal sulphide assemblages: polymetallic, pyrite–sphalerite–chalcopyrite–galena ± arsenopyrite assemblages (type I) and pyrite–chalcopyrite ± sphalerite ± pyrrhotite assemblages (type II). Type I assemblages occur in deposits with dominantly felsic host rocks, whereas type II assemblages are restricted to deposits in mafic-dominated ophiolite sequences. Free gold grains were observed in samples from eight different deposits in both type I and type II assemblages. X-ray emission spectra and electron microprobe analyses of the gold indicate that most grains are electrum, although a Au-bearing telluride occurs at Point Leamington. Ion microprobe analyses indicate that as much as 50% of bulk gold may be present as "invisible gold" locked in pyrite or arsenopyrite (up to 140 ppm Au at Point Leamington). Well-preserved primary depositional features in gold-bearing sulphides from several deposits suggest that the gold in type I assemblages is syngenetic. A strong correlation between gold and a polymetallic suite of Zn, Ag, Pb, As, and Sb, similar to that observed in Kuroko-type massive sulphides and in modern seafloor sulphides, supports a primary origin for gold in type I assemblages. In type II assemblages primary depositional features have been largely destroyed by deformation and annealing of sulphide grains. Gold is locally enriched in Zn-rich sulphides, and sulphides containing abundant pyrrhotite have the lowest gold contents. However, consistent geochemical associations with other elements are not observed, and this may reflect the strong remobilization of gold during structural deformation. The abundant free gold in some type II assemblages is a product of recrystallization during deformation and was derived locally from primary gold originally present in the host sulphides.
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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, no. 5 (May 3, 2021): 488. http://dx.doi.org/10.3390/min11050488.
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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.
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Belogub, E. V., C. A. Novoselov, B. Spiro, and 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, no. 2 (April 2003): 339–54. http://dx.doi.org/10.1180/0026461036720105.
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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.
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Pieczonka, Jadwiga. "Polymetallic mineralization in Triassic strata of the NW part of the Kraków-Częstochowa Monocline." Mineralogia 41, no. 1-2 (January 1, 2010): 35–53. http://dx.doi.org/10.2478/v10002-010-0004-1.
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Polymetallic mineralization in Triassic strata of the NW part of the Kraków-Częstochowa MonoclineA new association of ore minerals has been found in the Lower and Middle Triassic rocks in the vicinity of the village of Woźniki in the NW part of the Upper Silesian district. In addition to the typical Zn-Pb-Fe association in dolomites, copper sulphides have been detected in the sandstones and conglomerates of the Lower Bunter. Copper mineralization occurs in the sandstone matrix and is represented by bornite, chalcopyrite, chalcocite, tetrahedrite and covellite. High admixtures of zinc in Cu sulphides and admixtures of copper in Zn-Pb sulphides suggest a common source for the metal-transporting fluids and a single period of sulphide crystallization.
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Kotwica, Łukasz, Ewa Kapeluszna, Piotr Stępień, Jan Deja, Mirja Illikainen, and Łukasz Gołek. "Influence of Sulphides on Hydration of Ground Granulated Slag Alkali Activated Mortars and Pastes." Key Engineering Materials 761 (January 2018): 92–95. http://dx.doi.org/10.4028/www.scientific.net/kem.761.92.
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Influence of sodium sulphide on properties of sodium hydroxide activated ground granulated blast furnace slag was investigated. Properties of both fresh (cone flow, density) as well as hardened (compressive strength) mortars were determined. Early hydration of pastes was investigated using conducting calorimetry. Results showed, that introduction of sodium sulphide to caustic soda activated slag only slightly influence the course of hydration process. Early strength is increased by about 10%. In later periods strength is virtually not affected by the presence of sodium sulphide. Those observations are confirmed by calorimetric results. Presence of sodium sulphide causes slight decrease in consistency of mortars. Colour of mortars is also affected by the presence of sulphides. It is more darker and it is most probably due to the reducing properties of sulphide ions. Results of model investigations on precipitated C-S-H phase showed, that presence of sulphides results in increased main basal spacing of C-S-H phase as determined by XRD.
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McDonald, Mervin, Stephen Piercey, Graham Layne, Lee Pigage, and Glenn Piercey. "Mineral Assemblages, Textures and In Situ Sulphur Isotope Geochemistry of Sulphide Mineralization from the Cyprus-Type Ice Volcanogenic Massive Sulphide (VMS) Deposit, Yukon, Canada." Minerals 8, no. 11 (November 1, 2018): 501. http://dx.doi.org/10.3390/min8110501.
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The Permian (~273–274 Ma) Ice volcanogenic massive sulphide (VMS) deposit represents a mound shaped Cyprus (mafic)-type VMS deposit (~4.5 Mt @ 1.5% Cu) hosted in basaltic rocks of Slide Mountain terrane. The deposit consists of massive sulphides that are underlain by a chlorite-sulphide-hematite-rich stringer pipe, and overlain by a hematite-(pyrite)-rich exhalative chert. The sulphides are divided into five facies: (1) pyrite-rich; (2) pyrite-bornite-rich; (3) pyrite-chalcopyrite-rich; (4) hematite-pyrite; and (5) stringer sulphide. The sulphides have a distinct paragenetic and textural evolution in the massive sulphide that reflect: (1) an early, low temperature stage (<250 °C dominated by Fe-Zn-Cu-rich mineralization; (2) an intermediate, high temperature stage (>300 °C) dominated by Cu-Fe-rich mineralization; and (3) a late, low temperature phase (<150 °C) dominated by Fe-rich mineralization. In situ sulphur isotope data pyrite and chalcopyrite (by secondary ion mass spectrometry (SIMS)) range from δ34S = +1.8‰ to +8.2‰, but vary as a function of paragenesis and temperature of deposition. Both early and late forming sulfides were dominated by sulphur from partial thermochemical sulphate reduction (TSR) of seawater sulfate, whereas intermediate, high temperature mineralization was dominated leached, igneous sulphur from basement rocks. These results are similar to modern seafloor vents and many ancient VMS deposits.
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Oszczepalski, Sławomir, and Andrzej Chmielewski. "Mineralization of the Zechstein Lower Anhydrite in the Fore-Sudetic Monocline." Biuletyn Państwowego Instytutu Geologicznego 472, no. 472 (November 20, 2018): 135–54. http://dx.doi.org/10.5604/01.3001.0012.7116.
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The paper presents the characteristics of ore mineralization of the Lower Anhydrite in the Fore-Sudetic Monocline. Both reduced and oxidized (Rote Fäule) rocks have been investigated. Reduced anhydrites are characterized by significant variability of metal concentrations and sulphide minerals. The most intensely mineralized anhydrites occur above the oxidized bottom part of the Lower Anhydrite. Mineralization in this part is dominated by copper sulphides (chalcocite, digenite, covellite, bornite and chalcopyrite) which are accompanied by galena and sphalerite. Further away from the oxidized zone, zinc and lead sulphides predominate over copper sulphides, and pyrite mineralization is also observed. Complex intergrowths and replacement textures of sulphides, as well as intergrowths of the ore minerals with sulphates and carbonates are considered to have formed after lithification of the enclosing sediments, and indicate that the original associations of sulphides were overprinted by superimposed later mineralization. Oxidized anhydrites generally have no significant concentrations of metals like Cu, Pb and Zn. The relict mineralization there is represented by remnants of tiny grains of copper sulphides (mainly covellite, digenite and chalcocite) and pyrite, profoundly altered as a result of their partial replacement by hematite. This mineralization present in the oxidized anhydrites indicates that hematite emplacement overlapped deposition of the original sulphides and extended oxidation up into the Lower Anhydrite. Position of the reduced and oxidized areas of anhydrites enriched in metals indicates centres of the most intense activity of the ascending mineralizing fluids.
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Gajic, Natasa, Zeljko Kamberovic, Zoran Andjic, Marija Korac, Jarmila Trpcevská, and Mirko Stamatovic. "Improving the synthesis process of tribological materials based on tin sulphides by adding graphite as additive." Journal of the Serbian Chemical Society 84, no. 4 (2019): 423–33. http://dx.doi.org/10.2298/jsc180628102g.
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The aim of this research was to study the effect of graphite addition in the process of synthesis of tribological materials based on tin sulphides. The tin sulphides powders were synthesized from selected precursors by pyrometallurgical method in rotary tilting tube furnace. The thermodynamic parameters of the synthesis were determined using HSC Chemistry software modelling package. In addition, the synthesis process was also characterized by the thermal analysis method: simultaneous differential scanning calorimetry and thermogravimetry (DCS-TGA). The characterization of the synthesized tin sulphides powders included analysis of chemical composition by optical emission spectroscopy, phase composition identification by X-ray diffraction (XRD) and examination of morphology, as well as elemental composition by scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). The hexagonal SnS2 and orthorhombic Sn2S3 phases were formed after the thermal treatment of starting powders in nitrogen atmosphere. The obtained results indicate the positive effects of the graphite addition which enables the synthesis of tin sulphide powders with appropriate content of sulphide phases with minimal loss of sulphur.
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Hampton, W. A., G. P. White, P. W. O. Hoskin, P. R. L. Browne, and K. A. Rodgers. "Cinnabar, livingstonite, stibnite and pyrite in Pliocene silica sinter from Northland, New Zealand." Mineralogical Magazine 68, no. 1 (February 2004): 191–98. http://dx.doi.org/10.1180/0026461046810180.
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AbstractSilica sinter masses in the southern portion of the Pliocene Puhipuhi geothermal field of Northland, New Zealand, have recrystallized to microcrystalline quartz and moganite but many primary depositional fabrics of the sinters can still be recognized. Finely disseminated cinnabar, acicular stibnite, pyrite framboids and minor livingstonite are distributed through both massive sinter and stromatolitic fabrics with sulphide mineralization extending from fractured rocks about former spring vents into less disturbed sinter layers. The deposition of sulphides in the sinters is part of a continuum of mineralization resulting from the former hydrothermal regime and which extends to depth in the extinct geothermal system. Periodic changes in the hydrology, such as repeated fracturing following fracture sealing facilitated episodic sulphide deposition. Mercury is considered to have travelled in the liquid phase with antimony and precipitated directly as cinnabar. Remobilization of the sulphides, along with the recrystallization of the sinter masses, have produced complex textural relations. The multifaceted paragenesis of the sulphides is reflected in the range of their minor and trace element compositions revealed by electron microprobe analyses.
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Jasiński, A. W. "Conditions of formation of the iron-containing minerals, Hällefors silver mines, Bergslagen, Sweden." Mineralogical Magazine 50, no. 355 (March 1986): 101–10. http://dx.doi.org/10.1180/minmag.1986.050.355.13.
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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.
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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, no. 2 (February 1, 1992): 209–21. http://dx.doi.org/10.1139/e92-020.
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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.
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CAPEILLÈRE-BLANDIN, Chantal, Christelle MARTIN, Nicoletta GAGGERO, Piero PASTA, Giacomo CARREA, and Stefano COLONNA. "Sulphoxidation reaction catalysed by myeloperoxidase from human leucocytes." Biochemical Journal 335, no. 1 (October 1, 1998): 27–33. http://dx.doi.org/10.1042/bj3350027.
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The oxidation of alkyl aryl sulphides by myeloperoxidase (MPO) at the expense of hydrogen peroxide was investigated under steady-state conditions. The sulphide concentration effect was studied under saturating H2O2 concentrations at pH 5.0 and 20 °C. The kinetic constants, kcat and Km, of the different substrates were determined and the values were in the 1–10 s-1 range and around 43±26 µM respectively, whatever the sulphide considered. In the case of p-substituted thioanisoles, the oxidation rate was dependent upon the substituent effect. The correlation of log(kcat) with the substituent constants (δ+ values) (Hammett equation) could be explained by a reaction mechanism involving the enzyme compound II and a sulphenium radical cation. This conclusion was also supported by spectrophotometric analysis of catalytic intermediates of the enzyme, showing the accumulation of compound II. Moreover, chiral HPLC analyses showed that MPO oxidation of alkyl aryl sulphides produced the corresponding (R)-sulphoxides with a low enantioselectivity (4–8%). Chloride ion effects on the MPO-catalysed oxygenation of sulphides were also studied. Chloride acted as a substrate for MPO and as an activator in MPO-catalysed sulphoxidation. Inhibition occurred at chloride concentrations above 120 mM, whereas below 120 mM, chloride increased the reaction rate when using p-tolyl methyl sulphide as the substrate. In the presence of 100 mM chloride the catalytic efficiency (kcat/Km) of MPO increased 3–4-fold, whatever the sulphide considered, but racemic products were obtained. These data have been interpreted in the light of known structural information on the accessibility of the distal haem cavity.
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Goodfellow, Wayne D., and Jan M. Peter. "Sulphur isotope composition of the Brunswick No. 12 massive sulphide deposit, Bathurst Mining Camp, New Brunswick: implications for ambient environment, sulphur source, and ore genesis." Canadian Journal of Earth Sciences 33, no. 2 (February 1, 1996): 231–51. http://dx.doi.org/10.1139/e96-020.
Full textAbstract:
The Brunswick No. 12 massive sulphide deposit occurs within a Middle Ordovician bimodal volcanic and sedimentary sequence that is thought to have formed in a continental back-arc rift covered with a thick succession of carbonaceous hemipelagic and turbiditic sedimentary rocks. The deposit consists of three en echelon lenses that are zoned from Vent Complex to Bedded Ore and Bedded pyrite facies. The Bedded Ore facies has the lowest average δ34S values (14.2[Formula: see text]), but are only slightly less positive than laminated pyrite in footwall sedimentary rocks (δ34Smean = 15.1[Formula: see text]). δ34S values for the bedded sulphides show an upward increase from 14.2[Formula: see text] in Bedded Ore to 16.5[Formula: see text] in Bedded Pyrite. Average δ34S values for Vent Complex (15.8[Formula: see text]) and underlying stringer sulphides (16.1[Formula: see text]) are consistently more positive than those for Bedded Ore. In carbonaceous shales and siltstone of the Patrick Brook Formation that underlie the deposit, δ34S values that range between 13.8 and 25.6[Formula: see text], and the similarity of these values to those of the Brunswick No. 12 deposit indicate major bacterial reduction of sulphate to sulphide under closed or partly closed conditions, and that most of the S in the deposit originated from ambient sulphidic bottom waters. Furthermore, the average δ34S value for Brunswick No. 12 bedded ores lies on the Selwyn Basin pyrite evolutionary curve and indicates that anoxic conditions within the Tetagouche back-arc basin reflect a global anoxic episode. The Brunswick No. 12 deposit probably formed, therefore, by the mixing of hydrothermal metals with dissolved sulphide of seawater origin during periods of ocean anoxia. The increase of δ34S values towards the Vent Complex may reflect the addition of isotopically heavy S formed by the inorganic reduction of seawater sulphate.
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Parnell, John, Sean McMahon, and Adrian Boyce. "Demonstrating deep biosphere activity in the geological record of lake sediments, on Earth and Mars." International Journal of Astrobiology 17, no. 4 (October 2, 2017): 380–85. http://dx.doi.org/10.1017/s1473550417000337.
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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.
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Cook, Nigel J., Christopher Halls, and Alan P. Boyle. "Deformation and metamorphism of massive sulphides at Sulitjelma, Norway." Mineralogical Magazine 57, no. 386 (March 1993): 67–81. http://dx.doi.org/10.1180/minmag.1993.057.386.07.
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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.
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Borma, Laura De Simone, Maurício Ehrlich, and Maria Cláudia Barbosa. "Acidification and release of heavy metals in dredged sediments." Canadian Geotechnical Journal 40, no. 6 (December 1, 2003): 1154–63. http://dx.doi.org/10.1139/t03-062.
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The oxidation of iron sulphides in dredged sediments can be a source of long-term contamination of surface and underground water. The adverse effects are related to a decrease in the ability of soil to retain heavy metals, which is caused by acidification. Laboratory tests were conducted, and pH variations and consequent release of heavy metals, especially Zn, Cu, and Pb, into the solution were monitored over time. The rate of pyrite oxidation was determined based on the sulphate production rate, through the stoichiometry of the oxidation reaction. Samples of sediments from the Jacarepaguá lagoon complex, State of Rio de Janeiro, were dried and oxidized over a period of 10 months. During this period the pH fell from 6.9 to 3.3, with oxidation of approximately 20% of the sulphur present in the form of iron sulphide, and 45% of the Zn, 15% of the Pb, and 5% of the Cu contained in the material were released. The oxidation rate at the initial stages was of the order of 1.0 × 104 g(O2)·h1, decreasing to 1.0 × 105 g(O2)·h1 during the test. This study presents the laboratory methodology developed for determining the oxidation rate in a system where the oxygen consumption is governed not only by the pyrite oxidation, but also by the organic matter. In these experiments, a key measure of intrinsic oxidation rate (IOR) is the oxidation rate where oxygen is freely available at normal atmospheric concentration. By comparing the values obtained for the dredged material with the results of the IOR of mining waste materials reported in the literature, it was observed that the oxidation rates of the iron sulphide formed in the Jacarepaguá lagoon environment were one to two orders of magnitude higher than those of mineral iron sulphides from coal wastes. This behavior can be explained considering that the iron sulphides in dredged materials are freshly formed and have more specific surface area exposed to air than the iron sulphide mineral in mining wastes.Key words: sediments, dredging, sulphides, oxidation, acidification, heavy metals.
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Butt, Muhammad Tahir, Naz Imtiaz, Naeem Abbas, and Rauf Ahmad Khan. "Sulphide Removal from Sewage Wastewater by Oxidation Technique." Pakistan Journal of Scientific & Industrial Research Series A: Physical Sciences 60, no. 1 (February 28, 2017): 42–49. http://dx.doi.org/10.52763/pjsir.phys.sci.60.1.2017.42.49.
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In this study sewage wastewater samples were collected from different areas of Lahore, Pakistanfrom the WASA sewer system and then different chemical oxidizers: O2, KMNO4, H2O2 were used toremove the sulphides from these samples for selection of suitable oxidizer for treatment. From these results,it was observed that H2O2 was found effective and suitable for treatment and it can be used for this purpose.Theoretical and experimental doses required for treatment were similar. The KMNO4 oxidation reactionswere completed in five minutes time while H2O2 required more time and removed sulphide completelywith slow chemical reaction. Different doses of oxidizer such as 1 to 6 g of oxygen, 1 to 14 g of KMNO4,1to 11 g of H2O2 with different ratios were used and H2O2 was found suitable. Using 11 g of H2O2 dose,100 % sulphides were removed, H2O2 as an oxidizer was found more suitable for sulphide removal fromwastewater.
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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, no. 1 (January 1, 1985): 15–26. http://dx.doi.org/10.1139/e85-002.
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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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Meyer, Edson, Asanda Bede, Nyengerai Zingwe, and Raymond Taziwa. "Metal Sulphides and Their Carbon Supported Composites as Platinum-Free Counter Electrodes in Dye-Sensitized Solar Cells: A Review." Materials 12, no. 12 (June 20, 2019): 1980. http://dx.doi.org/10.3390/ma12121980.
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Energy sufficiency is a critical requirement for the economic prosperity of modern countries. Efficient harnessing of solar energy using technologies such as the dye-sensitized solar cell could solve the energy problem which persistently plagues developing countries. Despite having a simple operational procedure and modest power conversion efficiency of 13.8%, the dye-sensitized solar cell consists of an expensive platinum counter electrode which makes commercial success futile. Thus, this review intends to establish the progress researchers have attained in the development of sulphide based counter electrodes as alternatives to platinum, thereby lowering cost of production. Metallic sulphides are good electrocatalysts and cheap, hence, they possess the necessary requirements for effective functional counter electrodes. Furthermore, ternary metallic sulphides are known to exhibit higher efficiencies stemming from the synergistic effect produced by the co-existence of two metal ions in a crystal structure, which is believed to induce greater catalytic capability. Incorporation of metallic sulphides with carbon materials, which are exceptional electrical conductors, could potentially produce more efficient counter electrodes. In that regard, this review seeks to establish the effect recently developed composite counter electrodes comprising metallic sulphides and carbon-based materials have induced on the functionality of the counter electrode (CE).
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Veneu, Diego Macedo, Thais Ferreira Marks Brasil Duque, Getúlio Gomes Oliveira Júnior, Rodrigo Barsante Gomides, Claudio Luiz Schneider, and Marisa Bezerra de Mello Monte. "SELECTIVE FLOTATION OF SULPHIDES FROM A GOLD MINING OPERATION." Engevista 19, no. 2 (May 8, 2017): 447. http://dx.doi.org/10.22409/engevista.v19i2.861.
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This paper presents a study to obtain sulphide as byproducts of a concentrated cleaner of gold generated from the flotation process of sulphide gold ore of mine Morro do Ouro. Chemical analysis of the concentrated of gold showed a content of approximately 22.05% S, in the form of a bulk sulphides. The liberation of the sulphides was measured using a SEM with second generation automated mineralogy (MLA). For the chalcopyrite recovery step, the fraction of liberated gangue particles is above 90%, for galena up to 92% and sphalerite above 96%, in all sizes. Moreover, the fractions of particles of minerals of interest that are completely liberated is below 0.52% for the chalcopyrite recovery step, 0.65% for galena and 0.28% for sphalerite, in all sizes. The use of collectors Aero 3894, 3418A and 5100 allowed greater selectivity in the flotation circuit presented. The recoveries of chalcopyrite, galena and sphalerite in the Rougher steps were 82%, 73% and 62%, respectively.
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Duckworth, Rowena C., and David Rickard. "Sulphide mylonites from the Renström VMS deposit, Northern Sweden." Mineralogical Magazine 57, no. 386 (March 1993): 83–91. http://dx.doi.org/10.1180/minmag.1993.057.386.08.
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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.
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Mikulski, Stanisław Z., Katarzyna Sadłowska, Janina Wiszniewska, and Rafał Małek. "Vanadium and Cobalt Occurrence in the Fe-Ti-V Oxide Deposits Related to Mesoproterozoic AMCG Complex in NE Poland." Applied Sciences 12, no. 12 (June 20, 2022): 6277. http://dx.doi.org/10.3390/app12126277.
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On the basis of geochemical whole-rock and mineralogical point analyses, the concentrations of V and Co were determined in magnetite-ilmenite oxide ores, associated with sulphides, at the Krzemianka and Udryn deposits in the Mesoproterozoic Suwałki Anorthosite Massif (SAM) in NE Poland. EPMA analyses showed that the main carrier of vanadium was magnetite (mean = 0.42 wt%) and, to a lesser extent, ilmenite (mean = 0.14 wt%) and minor Al-spinels (mean = 0.04 wt%). In turn, cobalt was found mainly in the form of isomorphic substitutions in magmatic sulphides such as pentlandite (mean = 4.41 wt% Co), pyrrhotite (mean = 0.16 wt%), and chalcopyrite (mean = 0.11 wt%). Moreover, Co-enrichments were also recognized in the secondary sulphides, such as pyrite and bravoite, replacing pyrrhotite (means = 1.6 and 2.7 wt% Co, respectively), and in the form of different thiospinels ((Fe, Ni) (Co, Ni)2S4), mainly siegenite (mean = 22.0 wt% Co), replacing pyrrhotite and pentlandite. Vanadium cations were substituted in Fe, Ti oxide minerals in place of Fe+3 cations, and in the case of cobalt, Fe+2 cations were substituted in sulphides and thiospinels. Vanadium and cobalt showed high Person’s correlation coefficients (r = 0.70), indicating their close spatial coexistence and a common source, which was parental anorthosite-norite magma of the SAM suites. The common magma genesis of magnetite-ilmenite and sulphide mineralization was also confirmed by the very similar shapes of the curves of REE content in the oxide-sulphide ores in relation to chondrite, in which negative Eu anomalies and positive Sm anomalies are clearly visible. Although the average contents of vanadium and cobalt were low (arithmetic means = 960 ppm, and 122 ppm, respectively), the resources of these metals were estimated to be large due to the enormous reserves of magnetite-ilmenite ores hosted by the SAM. However, the Fe-Ti-V ores associated with Fe, Ni, Co, and Cu sulphides were considered to be sub-economic because of their depth of occurrence (mainly 1.0 km below the surface level); their metal contents, which were usually too low; and additionally the fact that the location is in a highly environmentally protected landscape and lake area.
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Gamanyuk, S. B., M. V. Kirilichev, and G. V. Babin. "Investigation of Formation Features of Sulphide Inclusions and their Distribution inside the Grain Depending upon the Conditions of Steel 20 Deoxidation." Materials Science Forum 945 (February 2019): 592–97. http://dx.doi.org/10.4028/www.scientific.net/msf.945.592.
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The paper reports laboratory test findings on the impact of steel oxidation level on distribution features of non-metallic inclusions in low-alloyed structural steels. An analysis of the effect of various oxidation methods of steel on the distribution and formation of non-metallic inclusions is made. The results reveal a relation between the amount of sulphide and oxisulphide inclusions formed and steel oxidation level. The release of oxisulphide from the melt is accompanied with a decrease in the amount of both oxygen and sulphur. After oxygen content has achieved an equilibrium value, only “pure” sulphides are formed, which may deteriorate steel plastic properties. Thus, sulphides start precipitating only when oxygen content in the melt falls to a very low value. An increase in the amount of oxysulphides is accompanied with a decrease in sulphur concentration in the melt which reduces sulphide phase concentration at grain boundaries and stabilizes plastic properties. Thus the negative effect of sulphur can be reduced not only by decreasing its content in steel through expensive secondary steelmaking methods but also by controling the amount, shape and types of oxide, sulphide and oxisulphide inclusions in steel.
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Scott, R. A., R. A. D. Pattrick, and D. A. Polya. "Origin of sulphur in metamorphosed stratabound mineralisation from the Argyll Group Dalradian of Scotland." Transactions of the Royal Society of Edinburgh: Earth Sciences 82, no. 2 (1991): 91–98. http://dx.doi.org/10.1017/s0263593300007574.
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ABSTRACTSulphur isotopic data are presented for the four horizons of stratabound mineralisation in the Argyll Group Dalradian (Vendian) of the Central Highlands of Scotland. The styles of mineralisation reflect the stratigraphic and tectonic evolution of the Dalradian basin. The SEDEX-type Ba + (Zn + Pb) Loch Lyon Horizon has δ34S values for pyrite of +17% and for baryte of +27%. The baryte sulphur source was Dalradian sea-water although the values were modified by isotopic exchange with an H2S-rich metamorphic fluid derived from the surrounding graphitic schists. The sulphur source for sulphide in the horizon was probably the underlying strata; sulphide values were only slightly affected by metamorphism. Sulphides in the Pyrite Horizon are isotopically indistinguishable from those in the remainder of the volcanogenic Ben Lawers Schist Formation (0 ± 4%); these values suggest that, at least in the Tyndrum area, sulphides in the Pyrite Horizon are of igneous origin. VMS-type Cu + Zn + Pb mineralisation in the Ben Challum Quartzite Formation has a narrow range of values around + ll%. The likely source of this sulphide sulphur is reduced sea-water sulphate, the isotopic values remaining consistent owing to the buffering effect of anhydrite in the underlying calcium-rich rocks.
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Firstova, Anna, Tamara Stepanova, Anna Sukhanova, Georgy Cherkashov, and Irina Poroshina. "Au and Te Minerals in Seafloor Massive Sulphides from Semyenov-2 Hydrothermal Field, Mid-Atlantic Ridge." Minerals 9, no. 5 (May 15, 2019): 294. http://dx.doi.org/10.3390/min9050294.
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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.
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Adomako-Ansah, K., A. Boateng, and A. Asante. "Implications of Ore Textures for Gold Recovery at Esaase Deposit, Asanko Gold Mine." Ghana Mining Journal 22, no. 1 (June 30, 2022): 9–14. http://dx.doi.org/10.4314/gm.v22i1.2.
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The Esaase Deposit of the Asanko Gold Mine Ltd (AGM) contains a system of epigenetic gold-related quartz veins hosted by tightly folded and foliated metasedimentary rocks. The gold mineralisation is associated with disseminated sulphide minerals in the quartz-carbonate veins and within the alteration zones of the host metasedimentary rocks. AGM employs a combination of Gravity Concentration and Carbon-In-Leach (CIL) methods to recover its gold and this has resulted in a recovery rate that ranges from 81.3% to 94.1%. The high recovery rate (>90%) suggests that the gold is free and therefore not locked up in the sulphides that are associated with the mineralisation. However, the recovery rate drops from 94.1 to 81.3% even when the samples contain high amounts of sulphides. Since the presence of sulphides in altered rock is one major indicator of gold mineralisation, this research was conducted to determine the ore textural relationship between gold and sulphides and the implication of the ore textures on the current gold recovery methods employed on the deposit. Polished block sections were prepared from samples from the ore zones: Transition and Cobra. Ore petrographic studies were conducted on the samples using the Leica DM2700P petrographic microscope at the University of Mines and Technology, Tarkwa, Ghana. These studies revealed that the low gold recoveries may be attributed to the gold occurrence as inclusions in the sulphides, which is typical for refractory ores, thus, making it difficult to be extracted by the current method employed at Asanko. Therefore, AGM may have to consider the economics of employing a combination of other methods to liberate the refractory gold and possibly, result in optimum recovery.
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Cataliotti, Rosario Sergio, Giulio Paliani, and Sergio Santini. "Vibrational spectra of crystalline organic sulphides: dimethyl sulphide and diethyl sulphide." Canadian Journal of Physics 64, no. 1 (January 1, 1986): 100–106. http://dx.doi.org/10.1139/p86-014.
Full textAbstract:
The vibrational spectra of crystalline dimethyl sulphide and diethyl sulphide have been measured at 77 K. The comparison with the liquid-state spectra has provided the correlation between the normal motions of the free molecules and those of the molecules in the Bravais unit.All Davydov components in the solid-state spectra have been assigned with the aid of polarized infrared radiation, and the analysis of the unit-cell symmetry of both molecules has been derived.
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Kotzé, E., and 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, no. 4 (October 26, 2020): 551–72. http://dx.doi.org/10.25131/sajg.123.0033.
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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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Mitchell, R. H., and F. Belton. "Niocalite-cuspidine solid solution and manganoan monticellite from natrocarbonatite, Oldoinyo Lengai, Tanzania." Mineralogical Magazine 68, no. 5 (October 2004): 787–99. http://dx.doi.org/10.1180/0026461046850219.
Full textAbstract:
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.
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Prols, Janis, Ērika Teirumnieka, and Edmunds Teirumnieks. "Distribution of iron and iron compounds in the Kemeri - Jaunkemeri occurence of sulphide water." Environment. Technology. Resources. Proceedings of the International Scientific and Practical Conference 2 (June 17, 2015): 244. http://dx.doi.org/10.17770/etr2015vol2.626.
Full textAbstract:
Iron concentrations, distribution and migration forms, depending on pH and oxidation – reduction potential, were analyzed in case of the Kemeri-Jaunkemeri occurrence (area about 240 km<sup>2</sup>) of sulphide containing water (maximal sulphides concentration – 74 mg/l), located in Latvia. Iron content was investigated in 457 wells located within all area of occurrence. Those wells were installed to two aquifers: the Quarternary multi-aquifer and Salaspils aquifer, where occurrence of sulphide containing groundwater is distributed. All groundwater of occurrence is classified in four types depending on oxygen, sulphides and organic matter content in the groundwater. Modeling of groundwater migration forms was carried out, and it is stated that iron migrates basically as Fe<sup>2+</sup> in oxygen and suphides non-containing water. Migration forms are influenced by concentration of organic matter in the aquifer. The portion of Fe<sup>2+</sup> migrating in a form of free decreases due to formation of complexes with fulvic and humic acids, which can reach 36.5% of all migration forms. Iron migrates as Fe(OH)<sub>3</sub> in oxygen containing water (more than 99% of determined forms). Presence of iron is ascertained also in sulphides containing water, where iron migrates basically as (98.8% of determined forms). This occurs due to formation of complexes with sulphydes – FeHS<sup>-</sup> and Fe(HS)<sub>2</sub><sup>o</sup>.
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Spasova, Irena, Marina Nicolova, Plamen Georgiev, and Stoyan Groudev. "Comparative Variants of Microbial Pretreatment and Subsequent Chemical Leaching of a Gold-Bearing Sulphide Concentrate." Solid State Phenomena 262 (August 2017): 189–92. http://dx.doi.org/10.4028/www.scientific.net/ssp.262.189.
Full textAbstract:
A sulphide concentrate containing 31.4% total sulphur (in which 30.7% was sulphidic), 31.8% iron, 8.0% arsenic, 18.5 g/t gold and 32.9 g/t silver finely disseminated in pyrite and arsenopyrite as the most essential components was subjected to microbial pretreatment to expose the precious metals from the sulphide matrix. Three different types of microbial cultures were tested for their ability to oxidize the sulphides and to expose the precious metals for the subsequent chemical leaching: mesophilic chemolithotrophic bacteria with a temperature optimum for their growth and activity at about 32 – 37°C, moderate thermophilic bacteria with the relevant optimum at 53 – 59°C, and hyperthermophilic archaea at 75 – 84°C. The microbial pretreatment of the concentrate was carried out in reactors with mechanical stirring and enhanced aeration by air enriched in CO2. It was found that sulphide oxidation of about 40 – 45 % was sufficient for achieving gold extraction higher than 90% during the subsequent leaching of the pretreated concentrate by different gold-solubilizing reagent (cyanide, thiourea, thiosulphate). The highest rate of sulphide oxidation was achieved by a mixed culture of hyperthermophilic archaea at 82°C but at relatively low pulp densities (within 7 – 9%). At higher pulp densities (within 10 – 25%) the highest rates were achieved by means of moderate thermophilic bacteria at 57 – 59°C.
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Baláz, Peter, E. Boldižárová, and E. Godočíková. "Preparation of Nanocrystalline Copper and Copper Silicon Sulphide by Mechanochemical Route." Materials Science Forum 480-481 (March 2005): 453–56. http://dx.doi.org/10.4028/www.scientific.net/msf.480-481.453.
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The composition and properties of powders prepared by high-energy milling of copper sulphides with silicon have been studied by methods of X-ray diffractometry and surface area measurement. The combination of several methods was utilized to develop a coherent picture of the process. The overall process of mechano-chemical transformations in copper sulphide-silicon system proceeds via complicated mechanism with several overlapping steps. Phase transformations in copper sulphide phases, the formation of elemetal nanocopper with X-ray determined particle size of 23 nm and creation of ternary sulphide Cu8SiS6 with anomalous surface area values are the main products of the mechanochemical reaction.
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Van Dover, Cindy Lee. "Mining seafloor massive sulphides and biodiversity: what is at risk?" ICES Journal of Marine Science 68, no. 2 (June 30, 2010): 341–48. http://dx.doi.org/10.1093/icesjms/fsq086.
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Abstract Van Dover, C. L. 2011. Mining seafloor massive sulphides and biodiversity: what is at risk? – ICES Journal of Marine Science, 68: 341–348. Scientific exploration of the deep sea in the late 1970s led to the discovery of seafloor massive sulphides at hydrothermal vents. More recently, sulphide deposits containing high grades of ore have been discovered in the southwest Pacific. In addition to metal-rich ores, hydrothermal vents host ecosystems based on microbial chemoautotrophic primary production, with endemic invertebrate species adapted in special ways to the vent environment. Although there has been considerable effort to study the biology and ecology of vent systems in the decades since these systems were first discovered, there has been limited attention paid to conservation issues. Three priority recommendations for conservation science at hydrothermal vent settings are identified here: (i) determine the natural conservation units for key species with differing life histories; (ii) identify a set of first principles for the design of preservation reference areas and conservation areas; (iii) develop and test methods for effective mitigation and restoration to enhance the recovery of biodiversity in sulphide systems that may be subject to open-cut mining.
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Bahrami, Ataallah, Sajjad Chehreghani, Fatemeh Kazemi, Hamid Kazemi, Abdollah Forughirad, and Behnam Golizadeh. "THE MICROWAVE IRRADIATION EFFECT ON THE FLOATABILITY OF MIXED SULPHIDE/OXIDE COPPER ORES." Rudarsko-geološko-naftni zbornik 36, no. 4 (2021): 121–37. http://dx.doi.org/10.17794/rgn.2021.4.10.
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Pre-treatment of copper sulphide and oxide ores using microwave radiation causes a difference in their floatability through change in the surface properties of the minerals. The aim of this study is to investigate the behaviour of Sungun porphyry copper ore under the influence of microwave radiation. In this regard, the feed sample of Sungun copper flotation circuit has been subjected to microwave irradiation for 0-120 s and a radiation power of 0-600 W. The prepared samples were then subjected to flotation experiments. According to the results, the grade of sulphide and oxide Cu minerals, as well as the grade of Fe, increased by microwave irradiation in all experiments compared to the non-irradiated samples. At the same time, recovery rate has a reversed trend and decreased in all cases. Variations in the recovery rates of copper oxides and sulphides due to microwave irradiation are different. Increasing the power of irradiation resulted in a greater reduction in the recovery of copper oxides than of sulphides. On the other hand, increasing the power of microwave irradiation reduced the amount of iron recovery in the copper concentrate and with an increase in the duration of microwave irradiation, the reduction of iron recovery values is even more pronounced. Changes in the power and duration of microwave radiation have not had a significant effect on variations in oxide copper grade in flotation tailings. While the grade of sulphides in tailing is affected by the parameters of microwave irradiation and with an increase in power and duration of microwave irradiation, the grade of copper in tailing increases.
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Zhang, YiRan, Nawoong Yoon, and Maria E. Holuszko. "Assessment of Sortability Using a Dual-Energy X-ray Transmission System for Studied Sulphide Ore." Minerals 11, no. 5 (May 4, 2021): 490. http://dx.doi.org/10.3390/min11050490.
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In hard rock mining, sensor-based sorting can be applied as a pre-concentration method before the material enters the mill. X-ray transmission sensors have been explored in mining since 1972. Sorting ore of acceptable grade and waste material before processing at the mill can reduce the amount of tailings per unit of valuable metal in the mining operation and have many economic benefits. Ore samples used in this paper are from a polymetallic carbonate replacement deposit (gold-silver-lead-zinc sulphide) in Southeast Europe. This paper focuses on how the Dual-Energy X-ray Transmission (DE-XRT) data is generated and used for ore characterization and sortability for this sulphide ore. The method used in the DE-XRT analysis in this project is based on the dual-material decomposition method, which is used in the medical industry for radiology. This technique can distinguish sulphides from non-sulphides. However, the correlation developed between the DE-XRT response and the metal content is lacking. As a result, the DE-XRT response can only classify the material effectively but cannot reliably predict the metal content.
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Glindemann, D., J. T. Novak, and J. Witherspoon. "Aeration tank odour by dimethyl sulphoxide (DMSO) waste in sewage." Water Science and Technology 55, no. 5 (March 1, 2007): 319–26. http://dx.doi.org/10.2166/wst.2007.194.
Full textAbstract:
Sewage plants can experience dimethyl sulphide (DMS) odour problems by at least one mg/L dimethylsulphoxide (DMSO) waste residue in plant influent, through a DMSO/DMS reduction mechanism. This bench-scale batch study simulates in bottles the role of poor aeration in wastewater treatment on the DMSO/DMS and sulphate/H2S reduction. The study compares headspace concentrations of sulphide odorants developed by activated sludge (closed bottles, half full) after six hours under anoxic versus anaerobic conditions, with 0 versus 2 mg/L DMSO addition. Anoxic sludge (0.1–2 mg/L dissolved oxygen, DO) with DMSO resulted in about 50 ppmv DMS and no other sulphide, while DMSO-free sludge was free of detectable sulphides. Anaerobic sludge (no measurable DO to the point of sulphate reduction) with DMSO resulted in 22/4/37 ppmv of H2S/methanethiol (MT)/DMS, while DMSO-free sludge resulted in 44/8/2 ppmv of H2S/MT/DMS. It is concluded that common “anoxic” aeration tank zones with measurable DO in bulk water but immeasurable DO inside sludge flocs (nitrate reducing) experience DMSO reduction to DMS that is oxidation resistant and becomes the most important odorant. Under anaerobic conditions, H2S from sulphate reduction becomes an additional important odorant. A strategy is developed that allows operators to determine from the quantity of different sulphides whether the DMSO/DMS mechanism is important at their wastewater plant.