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1
Yemul, O. S. "Novel polyarylene sulphides". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1998. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/3370.
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Igiehon, Uwagboe Osamede. "Carbothermic reduction of complex sulphides". Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46358.
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Bayerköhler, Frieder [Verfasser] y Philipp [Akademischer Betreuer] Kurz. "Iron-molybdenum sulphides as proton reduction catalysts". Freiburg : Universität, 2017. http://d-nb.info/1144148901/34.
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Smit, Timotheus Servaas. "Hydrodesulphurization of thiophenes using transition metal sulphides". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/28084.
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O'Sullivan, Susan Nora. "The synthesis and application of chiral sulphides". Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/272788.
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Coimbatore, Dhandayuth Venkatesh. "Cerium chloride inhibition for high strength low alloy steel exposed to sulphide polluted seawater". University of Western Australia. School of Mechanical Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0134.
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[Truncated abstract] Corrosion of steel structures caused by sulphide is a common engineering problem encountered by many industries, such as the petroleum, chemical processing, mining and mineral processing industries. The control of sulphide corrosion is still a controversial topic among corrosion engineers. There is an absence of guideline for a reliable acceptable limit of sulphide level in service and each processing industry has its own empirical values. Selection of inhibitors in the sulphide environment depends on laboratory testing before its actual application in pipelines and reaction vessels. Many investigators have postulated the corrosion mechanisms due to sulphide based on operating envelopes such as pH, chloride, manganese, hydrogen sulphide, sulphate reducing bacteria levels and inhibitor concentration. It is recommended in the literature that the batch dosing of inhibitor and biocide needs to be evaluated in regards to sulphide reducing bacteria (SRB) level, which may produce sulphide concentrations up to 2000 ppm. Although sulphide scale formation may protect the base metal by providing a physical barrier, the detrimental effects of sulphide are often inevitable, such as stress corrosion cracking, hydrogen embrittlement, etc. Currently, there are many chemicals that are used as inhibitors to prevent corrosion by scavenging the sulphide from the environment. Cerium, a rare-earth element, is not used as inhibitor in the sulphide environment. Also, there are no previous research findings on the effects of compounds of rare-earth metals, such as cerium chloride (CeCl3), in sulphide environment. This research examines the corrosion behaviour of 0.4Mo-0.8Cr steel, a High Strength Low Alloy (HSLA) steel, in sulphide-polluted artificial seawater with the addition of CeCl3 and glutaraldehyde. ... It is postulated that the moderate inhibiting effect of CeCl3 is due to the scavenging effect thereby forming Ce2S3 complex. Further reaction of sulphide with steel resulted in ferrous sulphide, leading to an increased corrosion rate. It is also concluded that the CeCl3 interferes with both anodic and cathodic reactions in deaerated conditions. Addition of glutaraldehyde in the sulphide-polluted seawater was found to decrease the corrosion rate. According to the electrochemical measurements conducted, the concurrent addition of glutaraldehyde and CeCl3 appeared to have an added effect on reducing the corrosion of the steel, as evidenced by the increase of the open circuit potential during the short-term testing. From the weight loss measurements after 60 days, sulphide pollution in deaerated seawater was found to increase corrosion rate. This is attributed to the increase of sulphide activity whereby continual dissolution of steel was encountered. From the weight loss tests, it was found that the addition of CeCl3 and glutaraldehyde reduced the corrosion rate of the steel in the solutions containing 0-10 ppm sulphide. There is no noticeable corrosion rate decrease for the solution containing 100 ppm sulphide. The added effect of CeCl3 and glutaraldehyde to the SRB medium has resulted in lower corrosion rates. Further detailed experimentation is required to elucidate the corrosion reduction mechanism in glutaraldehyde-containing environments.
7
Mulligan, David John. "Reduction of sulphur dioxide over transition metal sulphides". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61916.
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Arterton, Bruce William. "Preparation related luminescent properties in II-VI sulphides". Thesis, Coventry University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386517.
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Atkins, Alison J. "Solid state studies of ternary oxides and sulphides". Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320791.
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Maynard, Jonathan. "The genesis of sulphides in the Shetland ophiolite". Thesis, Open University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358559.
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Masenya, Mamago Adolphina. "Computational modelling studies of precious mixed metals sulphides". Thesis, University of Limpopo, 2016. http://hdl.handle.net/10386/1725.
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Thesis (MSc. (Physics)) -- University of Limpopo, 2016The stabilities of PtS to PdS and PdS to PtS were investigated using density functional theory within the generalized gradient approximation. Their structural, electronic and mechanical properties were determined to show their stability and the effect of pressure on different compositions. We found good correlation of calculations with available ex-perimental data. The lattice parameters were observed to fluctuate with increasing con-centration for both systems. Furthermore, heats of formation were calculated to deter-mine the relative structural stability of the systems. They predict that the most stable structure is Pd50S50 P42/mmc and Pt25Pd25S50 P42/mmc being the least stable. Pd12.5Pt37.5S50 P42/m is the most stable and Pd50S50 P42/m being the least stable struc-ture. The Pt37.5Pd12.5S50 P1 was said to be the most stable structure and Pd50S50 P1 be-ing the least stable. The phonon dispersion calculations show that Pt50S50 P42/mmc, Pd50S50 P42/mmc, Pd12.5Pt37.5S50 P42/m and Pt50S50 P1 (derived from P42/mmc) are me-chanically stable, consistent with calculated elastic constants. The Pt25Pd25S50 P42/mmc show soft modes, which are due to vibrations of Pt and Pd atoms in the x - y plane which suggests the instability of the structure, in agreement with C66 being negative, and consistent with heats of formation. The lattice parameters decreased steadily with increasing pressure. An anomaly was observed in Pt50S50 P1 (derived from P42/mmc), where the c lattice parameter was found to increase with increasing pressure. The elec-tronic density of states (DOS) were performed on all compositions. The DOS were sub-jected to pressure and it was generally noted that the band gap increases with increas-ing pressure. It was observed that the smaller the band gap, the more stable the struc-ture. Furthermore, phonon dispersions under pressure show that compounds with the P42/mmc and P1 (from P42/mmc) symmetries display the mixing of lower and upper en-ergy bands at pressures above 30 GPa.
National Research Foundation
12
Gauld, Chris M. B. "Characterisation of sulphides from the INCO WD-16 Ni-Cu sulphide deposit, Wisner Township, District of Sudbury, Ontario, Canada". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0019/MQ46482.pdf.
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Harrison, Mark Robert. "One-dimensional, mixed-metal sulphides – structural and physical properties". Thesis, University of Hull, 2011. http://hydra.hull.ac.uk/resources/hull:5281.
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New one-dimensional sulphides based on Ba2CoS3 have been synthesised and their structural and electronic properties investigated. The starting point was the one-dimensional sulphide Ba2CoS3, which shows one-dimensional anti-ferromagnetism, metallic-like behaviour and a small negative magnetoresistance. Cationic substitutions were carried out on both the barium and cobalt sites of Ba2CoS3. The substitution of zinc for cobalt into Ba2CoS3 resulted in the formation of the series Ba2Cox1−xZnxS3 (x = 0.0-1.0). Ba2Co1−xZnS3 compounds maintain the one-dimensional structure but become paramagnetic and show semiconducting properties. Interestingly significant values of magnetoresistance (up to −25%) are found in the series. The origin of the magnetoresistance is currently unknown although it is suspected that there is some extrinsic contribution. The compound Ba2Co0.75Fe0.25S3 has also been successfully synthesised although attempts to form compounds with higher iron content were not successful. A large number of compounds in the series Ba2Zn1–xMxS3 (M = Fe, Mn, Cr, Ni) have also been synthesised and initial investigations into the properties of these materials show that again they exhibit negative magnetoresistance. Finally Ba1.9K0.1CoS3 has been synthesised although no investigation into the properties has yet been carried out.
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Green, Pamela Rose. "The synthesis and structure of ternary transition metal sulphides". Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284056.
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Whittles, T. J. "Electronic characterisation of earth-abundant sulphides for solar photovoltaics". Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3010978/.
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This thesis explores the electronic characterisation of materials for use as absorber layers within photovoltaic solar cells: an attractive solution to the energy crisis. Primarily, XPS was used to characterise CuSbS₂, Cu₃BiS₃, SnS, and Cu₂ZnSnS₄. All of these materials can be classified as earth-abundant: an important factor when considering materials that are both readily available and environmentally friendly. To varying degrees, all of these materials are established as potential absorber layers, with reports of successful, albeit low-efficiency devices. Also, the literature is often scant with regards to more fundamental characterisation of these materials, specifically in terms of how the underlying electronic structure affects properties that are pertinent to solar cells. Where XPS is utilised, it often lacks rigour, and is obfuscated by the complexities of the spectra. Work is then presented with two aims. First, to use a combination of high-quality XPS measurements and density of states calculations, in order to give insight into the electronic structure of the materials. Second, to present the full potential of XPS, as applied to solar absorbers, and how this technique complements others that are used for characterisation. Without exception, each material demonstrated natural band positions that make them unsuitable for use with established solar cell technologies. That is, a low IP (4.71–5.28 eV), resulting in a large CBO (0.5–0.85 eV) with CdS, for example. This offers some explanation to the poor efficiencies. These properties were found to be a consequence of the bonding nature of the valence and conduction bands, differing to the conventional absorber materials because of the influence of lone-pair electrons or other second-cation states. The power of XPS was demonstrated for application to absorber materials. The presence, effects, and formation pathways of contamination of the materials were elucidated using XPS, showing how the presence of such can act adversely to the performance of cells, especially with regards to oxidation, and also how these factors have been overlooked in the past. When coupled with other, complementary techniques, it has the ability to aid in the phase identification of a grown material, and also to help determine the presence of unwanted phases, which cause detriment to the device. For these applications, the methods, fitting procedures and analysis considerations detailed in this thesis should be followed. Research interest in these materials should be maintained based on the findings, with new approaches to cell design being aided by the characterisation methods developed here.
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David, Lorraine. "MBE growth and characterisation of metastable transition metal sulphides". Thesis, Heriot-Watt University, 2006. http://hdl.handle.net/10399/197.
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Olsen, Sarah. "Synthesis of Copper Sulphides: A Green Chemistry Microwave Approach". Thesis, KTH, Tillämpad fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279452.
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Condon, Brian D. "Stereoselective bond formation via lithiation of asymmetric acyclic sulfides". Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/29911.
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Hannaby, M. P. "Phenylthio-controlled migrations around rings". Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355872.
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Elwell, S. "A study of europium compounds in unusual oxidation states by Mossbauer spectroscopy and other techniques". Thesis, University of Kent, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235331.
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Thomson, G. F. "Palaeomagnetic and aeromagnetic studies of some sulphide deposits". Thesis, University of Newcastle Upon Tyne, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383983.
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Kemp, Anthony John. "The geochemistry of metalliferous concretions and their associated permo-triassic sediments from Budleigh Salterton, Devon". Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337174.
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McKie, Marion Catherine. "The chemistry of 1,3,4-oxathiazol-2-ones and related systems". Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/12633.
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Engin, Tahir. "Structural, magnetic and electron transport properties of mixed metal sulphides". Thesis, Heriot-Watt University, 2008. http://hdl.handle.net/10399/2059.
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The construction of cells that enables the electrical resistance of a material to be measured simultaneously with the collection of powder neutron diffraction data at a range of temperatures (4.2 :5 TIK:5 1000) is described. The cells have been used to investigate the origin of the anomalous electron-transport properties of the ternary sulphides, TICu6.ssS4, BaCu4S3 and CuFeS2. Data for TICu6.ssS4 reveal that the anomaly observed at 255 K is associated with a structural change from P41n to 141m on cooling due to a distortion involving a doubling of the e-axis of the unit cell. There,are .~/ two resistance anomalies observed in BaCu4S3. The first at 523 K is associated' with a phase transition from a two-phase mixture (Pllma + Cmem) to a Cmem phase, whilst the second anomaly can be correlated with the decomposition of the 'sample at 923 K. Variable temperature powder neutron diffraction reveals that CuFeS2 adopts a tetragonal antiferromagnetically ordered structure up to 748 K, above which it consists of a mixture of two phases until TN = 823 K, where a loss of magnetic order is coincident with a transformation to a cubic structure. Resistance anomalies are observed at each of those temperatures. A new family of vanadium-substituted chromium sulphides (VxCr2-xS3, 0 < x < 2) has been prepared and characterized by powder X-ray and neutron diffraction, SQUID magnetometry, electrical resistivity, and Seebeck coefficient measurements. Vanadium substitution leads to a single-phase region with a rhombohedral Cr2S3 structure over the composition range 0.0 < x:5 0.75, while at higher vanadium contents (1.6 :5 x < 2.0) a second single-phase region, in which materials adopt a cation-deficient Cr3S4 structure, is observed. Materials with the Cr2S3 structure all exhibit semiconducting behavior whilst those adopting Cr3S4-type structure exhibit metallic behavior. Materials in both single phase regions undergo a magnetic ordering transition at temperatures in the range 90 - 118 K. Materials with the Cr2S3 structure undergo a transition to a ferrimagnetic state, the nature of which has been determined by low-temperature neutron diffraction measurements. Structural studies of the mixed-metal sulphides, FexMnl_xS (0 :5 x :5 0.4) were performed using powder neutron diffraction. Rietveld refinements show that all samples adopt a cubic rock-salt structure (F'm3m) at room temperature. The Feo.2Mno.sS sample is essentially pure phase whilst materials with higher Fe content contain 3CFe7SS (21.3% in Feo.4Mno.6S). Low-temperature neutron diffraction reveals that all materials are magnetically ordered at temperatures in the range 180 - 185 K, below Which they show a structural distortion. The magnetic structure consists of ferromagnetically aligned layers, with antiferromagnetic coupling of adjacent layers. Electron-transport property measurements reveal that all the samples are Arrhenius semiconductors with activation energies that decrease with increasing Fe content.
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Wass, S. A. "Some reactions of iron and molybdenum sulphides and related compounds". Thesis, University of Reading, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370130.
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Auëner, Christian Carl. "The synthesis and characterisation of novel quasi one-dimensional sulphides". Thesis, University of Liverpool, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414855.
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Mueller, Moritz. "Biotic and abiotic alteration of hydrothermal sulphides at the seafloor". Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/69029/.
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When active venting has ceased, reduced minerals in hydrothermal mounds and sediments continue to provide an inorganic energy source for chemolithotrophic microbes. This research focuses on the nature of microbially-mediated metal transformations in hydrothermal sediments during sulphide alteration and their impact on the ultimate fate of hydrothermal sulphides on the seafloor. The core studied is more seawater altered than other cores studied at TAG and provides an insight into the bacterial and archaeal communities as well as the geochemical processes taking place in highly altered metalliferous sediments. This study combines geochemical approaches with microbiological and organic biomarker measurements within the suboxic transition zone of sulphidic sediments to characterise the reactions and microbial communities present. This integrated approach demonstrates that (a) there is biogeochemical zonation within the sediment sequence with distinct microbial communities present at the sulphide-oxic seawater transition, (b) the microbes identified are associated with Fe and S redox cycling, (c) Marinobacter sp. are dominant at the sulphide interface. There is a significant shift in the microbiological community across the redox transition zone in these sulphidic sediments. The microbial assemblage of the suboxic transition zone is dominated by Bacillus sp. which are microaerophilic whereas the sulphide layer assemblage is dominated by Marinobacter sp. which are Fe oxidisers. Based on biomarker assemblages and genetic analyses, archaeal (and to a certain degree bacterial) communities are comparable to other hydrothermal settings despite the low biomass present. Processes inferred to be important in this sediment include the S, Fe and N cycle, all potentially coupled to the release and uptake of a range of transition metals. Significant recycling of redox active species occurs in the suboxic transition zones present in the sediment core. Uranium concentrations are low compared with other less altered sulphidic hydrothermal sediments, and U is associated with the upper regions of the suboxic transition zone and is associated with enrichment of a suite of other transition metals (e.g. Cu, Mo, As and V). Massive electrodes were constructed from CuFeS2 (from Ireland and TAG) and FeS2 (from TAG) and studied in oxygenated artificial seawater under circumneutral conditions using electrochemical methods. The results can be explained by existing hypotheses about pyrite and chalcopyrite oxidation and their oxidation products. The oxidation status of Cu in covellite could be identified as Cu+1. Impurities found (as expected because natural samples were used) have no effect on the electrochemical behaviour of the electrodes. The impact of Marinobacter sp. on sulphide alteration was studied in detail using an electrochemical approach. The results demonstrate that Marinobacter aquaeolei enhances the rates of oxidation. Marinobacter species seem to be of special importance for weathering reactions on the seafloor and in hydrothermal settings like the TAG area.
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Swartbooi, Ashton Mark. "Precipitation of nickel and cobalt sulphides using different reactor configurations". Master's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/6696.
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The nickel reduction process produces a stream containing unreacted dissolved nickel and cobalt. Removal of these metals to optimum levels is desired, however, the product should also be easy to handle and the process easy to incorporate into the current system. There are various precipitation agents that can be used to remove metals from solution, these being hydroxide, carbonates or sulphides. Sulphide precipitation has been gaining increased attention because of the advantages it holds above the other methods. These include: - attainment of high degree of metal removal over a broad pH range; - effective removal of metals such as As, eu and Hg even at low pH; - low retention time required in the reaction tank because of high reactivity; - feasibility of selective metal recovery There are various methods of introducing the sulphide into the system as well, with a soluble sulphide source most commonly used. The problem with this, and coupled to the high reactivity of the sulphide ion, is the creation of high local supersaturation. The supersaturation governs all precipitation and crystallisation processes in the way that it features in nucleation and growth rates. In crystallisation processes, the supersaturation can easily be controlled by thermal methods of evaporation or cooling. However, in precipitation, the creation of supersaturation is by a reaction, which commonly leads to high supersaturation. Thus, to obtain a product that has good filterability and settling ability, methods for controlling the supersaturation in precipitation reactions needs to be investigated.
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Quezada, Reyes Víctor Alejandro. "Pretreatment to the leaching of copper sulphides minerals in oxidizing media". Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/670663.
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La producción chilena de cobre procede de la hidrometalurgia y la concentración; el concentrado de cobre es tratado tradicionalmente mediante pirometalurgia. De acuerdo a Cochilco, el cobre producido en el año 2019, vía hidrometalurgia, fue un 27.3% del cobre chileno producido. Sin embargo, se prevé que esta aporte baje a un 11.6% para el año 2029, debido al agotamiento de los óxidos de cobre y la aparición de los sulfuros, principalmente calcopirita, siendo este mineral refractario a condiciones convencionales de lixiviación.
Una opción para mejorar la eficiencia de lixiviación es el pretratamiento, especialmente el efecto del tiempo de curado. Esta variable mejora la cinética de disolución, principalmente en minerales sulfurados de cobre, sin embargo, existe escasa investigación al respecto. Estudios sobre el pretratamiento evalúan el efecto en la eficiencia de lixiviación pero no antes. Además, las reacciones que gobiernan estos fenómenos no han sido identificadas. Así, el objetivo de esta tesis es la evaluación del efecto del curado ácido en la extracción de cobre desde minerales sulfurados en condiciones oxidantes y en la presencia de cloruro.
Muestras puras de calcopirita, calcosina y un mineral industrial de mina han sido utilizadas. Se desarrollaron pruebas evaluando el efecto del tiempo de curado y la concentración de KNO3, NaCl y H2SO4 y analizadas por ANOVA (calcopirita). Los productos formados en el pretratamiento (aglomerados) se caracterizaron utilizando diversas técnicas, tales como: Difracción de rayos X, Microscopio electrónico de barrido y Microscopia de luz reflejada. Además, el efecto del pretratamiento ha sido evaluado en la eficiencia de lixiviación a varias temperaturas, los residuos de lixiviación también han sido caracterizados.
En el pretratamiento, el mineral de calcopirita y de mina, bajo las condiciones utilizadas en este estudio (15 kg/t of H2SO4, 25 kg/t of NaCl y 15 días de tiempo de curado), los siguientes productos fueron identificados: CuSO4, NaFe3(SO4)2(OH)6, Cu2Cl(OH) y S. Sobre la calcosina, bajo las condiciones utilizadas en este estudio, con 30 kg/t of H2SO4, 40 kg/t of NaCl y 7 días de tiempo de curado, los productos identificados fueron: Cu1.75S, Cu(OH)Cl, Na2SO4 and CuSO4. Finalmente, el pretratamiento mejora la eficiencia de lixiviación, entre 4 y 6%, alcanzando una extracción de cobre de 94% desde la calcopirita a 90 °C, fortaleciendo la hidrometalurgia como alternativa de tratamiento para minerales sulfurados de cobre.Copper production in Chile is developed by hydrometallurgical and concentration; copper concentrates are traditionally treated by the pyrometallurgical route. According to Cochilco, copper produced in 2019 by hydrometallurgical process represent a 27.3% of Chilean total copper production. However, this contribution is estimated to decrease to 11.6% by 2029, due to the depletion of copper oxides and the appearance of copper sulphides, mainly chalcopyrite, being this mineral refractory to conventional leaching conditions. An alternative to improve leaching efficiency is pretreatment prior to leaching, especially the effect of curing time. This variable can increases the kinetics of copper extraction, especially in sulphides ores, however, there is limited research about it. Studies on pretreatment evaluate the effect on leaching efficiency but not previous leaching. Furthermore, the reactions that govern this phenomenon have not been clearly identified. Therefore, the objective of this thesis is the evaluation of the effect of acid curing on the copper extraction from sulphides minerals in oxidizing media and in presence of chloride. A pure sample of chalcopyrite, chalcocite and a mine ore were used. Tests evaluating the effect of curing time, KNO3, NaCl and H2SO4 concentration have been carried out. The chalcopyrite sample effect was evaluated by ANOVA. The product generated in the pretreatment (agglomerates) has been characterized using different characterization techniques, such as: X-Ray diffraction, Scanning Electron Microscopy and Reflection Optical Microscopy. Furthermore, the effect of pretreatment has been evaluated on the leaching efficiency at different temperatures, leaching residues have also been characterized. In the pretreatment of the chalcopyrite sample and mine ore, under the conditions of 15 kg/t of H2SO4, 25 kg/t of NaCl and 15 days of curing time, the following products were identified: CuSO4, NaFe3(SO4)2(OH)6, Cu2Cl(OH) and S0. Regarding the chalcocite sample, under the conditions of with 30 kg/t of H2SO4, 40 kg/t of NaCl and 7 days of curing time, the following products were identified: Cu1.75S, Cu(OH)Cl, Na2SO4 and CuSO4. Finally, copper sulphides ore pretreatment improved leaching efficiency, between 4 and 6%, reaching a copper dissolution of 94% from chalcopyrite at 90 °C, strengthening the hydrometallurgy as an alternative treatment for copper sulphides ores.
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Legrand, Daniel L. "Surface studies of nickel and iron sulphides with implications for flotation". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ31158.pdf.
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d'Arbeloff-Wilson, Sarah. "Reactions of the phosphaalkyne, PCBu't with metal sulphides, selenides and tellurides". Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324201.
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Adegoke, Idowu Abiodun. "Experimental studies on hydrothermal mineral replacement of bornite by copper sulphides". Thesis, Adegoke, Idowu Abiodun (2021) Experimental studies on hydrothermal mineral replacement of bornite by copper sulphides. PhD thesis, Murdoch University, 2021. https://researchrepository.murdoch.edu.au/id/eprint/60897/.
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Pseudomorphic mineral replacement reactions occur in numerous geological processes (e.g. metamorphism, metasomatism, ore deposition, and chemical weathering) and anthropogenic processes (e.g., reservoir acidification, CO2 sequestration, acid mine drainage, materials syntheses, and minerals processing). Therefore, the understanding of the mechanism and kinetics of these reactions is important not only to geosciences but also to industrial applications. These reactions involve the replacement of a primary mineral by a product mineral in the presence of a fluid phase, with the product mineral preserving the external dimension of the primary mineral. In the early years, solid-state diffusion (SSD) was proposed as the main mechanism for such reactions, while over the past 20 years the importance of coupled dissolution-reprecipitation (CDR) mechanism has been recognized, especially at low temperatures when SSD is assumed to be a very slow process. However, it has recently been recognized that in some mineral replacement reactions the rate of solid-state diffusion can be comparable to the rate of dissolution-reprecipitation, and hence complex mineral textures can be produced from a synergy between SSD and fluid-mediated CDR processes. The interplay between SSD and CDR mechanisms has profound implications in our interpretations of petrological and geological observations, yet it has not been adequately studied so far. Also, the role of the bulk hydrothermal fluids in the formation of lamellae textures by solid-state diffusion process in parent phases that are free of fluid inclusions is still not well elucidated. These and other issues were addressed in this present study.
Thus, to better understand the interaction between SSD and CDR reactions, the replacement of bornite (Cu5FeS4) by copper sulphides was used as a model system. In the present thesis, a series of experimental studies have been conducted into the mineral replacement reactions of bornite by copper sulphides to obtain an insight into the kinetics and mechanisms of the replacement reactions, as well as the formation and evolution of porosity during the replacement reactions. The outcomes of these sets of experiments are summarised below:
In Chapter 2, the hydrothermal dissolution and replacement of bornite by copper sulphides was studied experimentally in pH 1 solutions at three temperatures (160, 180 and 200 °C) under anoxic conditions, and the effects of background additives (Na2SO3, CuSO4, CuCl2 and CuCl) on the replacement pathway were established.
The results revealed that the reaction firstly involved the decomposition of bornite to form chalcopyrite (CuFeS2) lamellae and digenite-I (Cu9S5) via fluid-induced solid-state diffusion (FI-SSD) of Fe3+ from bornite structure. As the reaction progresses, chalcopyrite was later replaced by the second generation of digenite (digenite-II). Subsequently, both digenite-I and -II were replaced by covellite (CuS) and/or chalcocite (Cu2S) via the CDR reaction mechanism, depending on the experimental conditions. In addition, nantokite (CuCl) and atacamite (Cu2Cl[OH]3) formed due to the reaction between the dissolved copper with Cl-rich hydrothermal fluids. The observed replacement reactions at the rim and along fractures, the preservation of the external shape of the original bornite grain, and the presence of porosity in the product phase are characteristic features of the CDR mechanism.
The first critical finding from this set of experiments is the fluid-induced exsolution of chalcopyrite lamellae and digenite from bornite. This is because the exsolution rate and lamellae size were sensitive to the composition of the fluids, and no exsolution was observed in the heating experiment in the absence of fluid. This FI-SSD mechanism is made possible by the near-identical topology of the crystal structure of bornite, chalcopyrite and digenite. Secondly, the replacement of bornite is multi-step but proceeds via different pathways under the various conditions studied. The interplay between the FI-SSD and CDR mechanisms resulted in complex reactions which cannot be easily predicted empirically.
In Chapter 3, a combined kinetic, textural and mineralogical study of the replacement of bornite by copper sulphides under oxic conditions is presented, in order to obtain insights into the competing reactions between FI-SSD and CDR reactions under oxic conditions. The mechanism and kinetic behaviour of the reactions were described by exploring the effects of key variables including pH (1-6), temperature (160, 180 and 200 °C) and time on the reaction kinetics, and on the evolution of mineralogy and sample textures.
Like the anoxic experiments, the resulting textures under oxic conditions also revealed the interplay between the FI-SSD and CDR mechanisms during the replacement of bornite. However, the most important distinctive difference from the anoxic conditions is that the ICP-OES results suggests both Cu and Fe removal into the solution at pH 1, and predominantly Cu-removal at pH 2, 3 and 5 during the FI-SSD under oxic conditons as against predominantly Fe-removal under anoxic condtions.
The kinetic behaviour shows a complex dependence on various physical and chemical parameters including temperature, pH and contact time. For example, the result revealed that the reaction rate increases with temperature at pH 1 to 3, and decreases with temperature at pH 4 to 6. This change in reaction trend is linked to a change in the rate-limiting step of the reaction. For the effect of pH, the rate decreases with increasing pH from 1 to 6 at 180 and 200 °C, while the results show a complex effect of pH at 160 °C.
There are several important findings from Chapter 3: (1) the dissolution and the replacement of bornite under oxic conditions not only changed with pH but also with temperature, (2) bornite is relatively kinetically stable at higher pH 4-6, while pervasive fast replacement/dissolution of bornite was observed at lower pH (1-3), and (3) the exsolution rate and lamellae distribution is dependent on pH, indicating a FI-SSD mechanism.
In Chapter 4, the formation and evolution of porosity during the replacement of bornite by copper sulphides under anoxic and oxic conditions were monitored using combined (ultra) small-angle neutron scattering (USANS/SANS) measurements and microscopic textural examinations. The USANS/SANS measurements were carried out under both dry conditions and after filling the open pores with contrast matching D2O-H2O fluid, which made it possible to differentiate open pores from closed pores.
The reactions created pores in the product phases, and all samples contained pores with very broad size distributions from nano to micrometre. Nearly all small pores (<20 nm) were closed while larger pores were mostly open. The textures resulted from the FI-SSD process are largely non-porous, while the products from CDR reactions presents high porosity. Porosity generation in the product phase(s) is due to molar volume and relative solubility differences between the parent and the replacing phase. Porosity dropped at the initial stage of the reaction, but increased again with the progressive replacement, reaching a maximum at complete replacement, and then porosity slowly dropped again, showing porosity creation during the replacement and evolution after the replacement reaction. Therefore, this study provides another experimental evidence demonstrating the transient and dynamic nature of porosity during mineral replacement reactions. Porosity coarsening also occurred during and after replacement reactions, likely driven by surface energy minimization via Ostwald ripening.
Overall, this experimental study provides new insights into the physical chemistry of bornite replacement in nature. The documented mineralogical and textural differences could be used as one of the paleoproxies of the chemistry (including pH) and temperature of the fluids responsible for the alteration of copper minerals and remobilization of metals in ore deposits. Particularly, this study shows that mineral replacement can proceed via the synergy between SSD and CDR mechanisms; this happens at geologically low temperatures (≤200˚C) in the chalcogenide systems under both anoxic and oxic conditions, and may be used to interpret observations in other mineral systems such as the silicate systems at amphibolite or eclogitic metamorphic grades. This study also provides insights about porosity formation and evolution in copper-iron sulphides interacting with hydrothermal fluids, and how different reaction mechanisms contributes to porosity evolution, suggesting that mineral porosity can evolve and may be annealed out over geological timescale.
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Deveci, Haci. "Bacterial leaching of complex zinc/lead sulphides using mesophilic and thermophilic bacteria". Thesis, University of Exeter, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341175.
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Keith, Manuel [Verfasser] y Karsten [Akademischer Betreuer] Haase. "From active submarine vent systems to fossil volcanic-hosted massive sulphide deposits: an in-situ analytical study of hydrothermal sulphides / Manuel Keith. Gutachter: Karsten Haase". Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2015. http://d-nb.info/1080362703/34.
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Poole, Mark Charles. "Synthetic and spectroscopic studies of organic sulphides, sulphoxides, sulphones, and their metal complexes". Thesis, University of Exeter, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332281.
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Moug, Richard T. "II/VI metastable sulphides : fundamental studies of MBE growth, characterization and nanostructure formation". Thesis, Heriot-Watt University, 2009. http://hdl.handle.net/10399/2279.
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This thesis presents a fundamental study of II-VI metastable sulfides. Details of the growth by Molecular Beam Epitaxy (MBE) and characterization of CrS,ZnS,MgS, and ZnMgSSe structures on GaP and GaAs substrates are presented. Multilayer structures of ZnS/CrS and ZnMgS/CrS were grown on GaP substrates and characterized using X-ray interference. Asymmetric X-ray spectra indicated the presence of mosaic structure in the layers. A discussion on solutions to the disordered surface is presented. Superlattice structures were designed to contain 100Å of CrS. These samples were sent to the Polish academy of science for further analysis of magnetic properties. The surface morphology of zinc blende MgS layers grown on ZnSe buffer layers has been investigated by AFM. Nanowire formation is studied as a function of flux ratio and MgS layer thickness. Typical wire dimensions were found to be 0.6μm (length), 900Å (width), and 20Å (height). The method of wire formation is consistent with an anisotropic relaxation of the MgS layer by mismatch dislocations leading to a surface instability by the Asaro-Tiller-Grinfield mechanism. RHEED patterns from zincblende MgS (100) surfaces have been observed during growth, annealing and both during and after irradiation of the surface with an Mg flux. The results are compatible with the c(2x2) surface being formed from a ZnMgS alloy which converts to a pure MgS 4x1 reconstruction on Mg irradiation. Samples containing ZnMgSSe alloy were grown and analyzed by X-ray Interference. The alloy composition was found to be Zn0.20Mg0.80S0.64Se0.36. Samples with this composition are shown to be single phase using transmission electron microscopy. Structures with Zn0.20Mg0.80S0.64Se0.36 barriers were grown with ZnSe quantum wells and CdSe quantum dots, and showed good quantum confinement. The incorporation of Zn0.20Mg0.80S0.64Se0.36 in an epitaxial lift off technology has also been demonstrated.
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Szkoda, Iwona. "Phase relations, structural studies and physical properties of mixed metal oxides and sulphides". Thesis, Heriot-Watt University, 2008. http://hdl.handle.net/10399/2212.
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The phase relations in three oxide systems; ZnO–BiVO4, Pb2V2O7–BiVO4 and PbO– BiVO4, have been studied and their phase diagrams over the whole component concentration range up to 1273 K have been established. As a result of solid-state reaction between ZnO and BiVO4 mixed at a molar ratio of 2:1 or among ZnO, V2O5 and Bi2O3, mixed at a molar ratio of 4:1:1, a new double vanadate BiZn2VO6 has been obtained. Its crystallographic system was determined, its unit cell parameters were calculated and its incongruent melting temperature was established. A new compound is also formed in the Pb2V2O7–BiVO4 system. It has been shown that BiVO4 and Pb2V2O7 react with each other forming a compound of the formula Pb2BiV3O11, when their molar ratio is equal to 1:1, or between PbO, Bi2O3 and V2O5, mixed at a molar ratio of 4:1:3. This material melts congruently and it crystallises in the triclinic system. A new series of non-stoichiometric sulphides Ga1-xGexV4S8 (0 x 1) has been synthesised by standard solid-state reaction. The samples have been characterised by powder X-ray and neutron diffraction, SQUID magnetometry and electrical transportproperty measurements. Structural analysis reveals that a solid solution is formed throughout this composition range. Magnetic measurements suggest that the ferromagnetic behaviour of the end-member phase GaV4S8 is retained at x 0.7. By contrast Ga0.25Ge0.75V4S8 appears to undergo antiferromagnetic ordering at ca. 15 K. All materials with x ¹ 1 are n-type semiconductors whose resistivity falls by almost six orders of magnitude with decreasing gallium content, whilst the end-member phase GeV4S8 is a ptype semiconductor. Powder neutron diffraction studies show that the cubic unit cell is retained for non-stoichiometric materials to the lowest temperatures studied. Single crystals of five erbium-chromium sulphides have been grown by chemical vapour transport using iodine as the transporting agent. Single-crystal X-ray diffraction reveals that in Er3CrS6, octahedral sites are occupied exclusively by Cr3+ cations, leading to onedimensional CrS4 5- chains of edge-sharing octahedra, whilst in Er2CrS4, Er3+ and Cr2+ cations occupy the available octahedral sites in an ordered manner. By contrast, in Er6Cr2S11, Er4CrS7 and Er8Cr3S15, Er3+ and Cr2+ ions are disordered over the octahedral sites. In Er2CrS4, Er6Cr2S11, Er4CrS7 and Er8Cr3S15, the network of octahedra generates an anionic framework constructed from M2S5 slabs of varying thickness, linked by onedimensional octahedral chains. This suggests that these four phases belong to a series in which the anionic framework may be described by the general formula [M2n+1S4n+3]x-, with charge balancing provided by Er3+ cations located in sites of high-coordination number within one-dimensional channels defined by the framework. Er4CrS7, Er6Cr2S11, Er8Cr3S15 ii and Er2CrS4 may thus be considered as the n = 1, 2, 3 and members of this series. Whilst Er4CrS7 is paramagnetic, successive magnetic transitions associated with ordering of the chromium and erbium sub-lattices are observed on cooling Er3CrS6 (TC(Cr) = 30 K; TC(Er) = 11 K) and Er2CrS4 (TN(Cr) = 42 K, TN(Er) = 10 K) whereas Er6Cr2S11 exhibits ordering of the chromium sub-lattice only (TN = 11.4 K). These four materials have been studied using neutron diffraction which allowed magnetic ordering to be examined.
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Guelou, G. P. L. "On the structural and physical properties of Earth-abundant sulphides for thermoelectric applications". Thesis, University of Reading, 2016. http://centaur.reading.ac.uk/68420/.
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The work presented in this thesis focuses on improving the thermoelectric performance of cost-efficient, widely available, non-toxic transition-metal sulphides. Three families of materials, titanium-disulphide derivatives, tetrahedrites and bornites, were investigated owing to their promising electrical and/or thermal properties. Alongside thermoelectric property measurements, structural characterisation and measurements of various physical properties were carried out in order to explain the relationship between structural and physical features. A series of composition CoxTiS2 (0 ≤ x ≤ 0.75) was synthesised and structural characterisation was carried out using a combination of powder X-ray diffraction and neutron diffraction analysis. Electrical and thermal transport property measurements, thermal analysis, magnetic susceptibility measurements and muon spectroscopy analysis were carried out to complete the investigation. The intercalation of cobalt within the van der Waals’ gap of TiS2 leads to the formation of three superstructure types, monoclinic M5S8 (x = 0.25), trigonal M2S3 (x = 1/3) and monoclinic M3S4 (x = 0.5). At intercalation levels x ≤ 0.20 and x ≥ 2/3, Co atoms randomly occupy octahedral sites. In the case of x ≥ 2/3, Co atoms also occupy tetrahedral sites. The thermoelectric properties of CoxTiS2 (0 ≤ x ≤ 2/3) have been systematically investigated. A figure of merit of 0.3 is obtained for CoxTiS2 (0.04 ≤ x ≤ 0.08) at 573 K, a 25 % improvement over pristine TiS2 and one of the highest figures of merit reported for a n-type sulphide at such a low temperature. A series with composition MoxTi1-xS2 (0 ≤ x ≤ 0.09) was synthesised and consolidated by hot-pressing and spark plasma sintering. The ball milling conditions used and the SPS processing lead to a power factor of S2ρ-1 ≈ 2.1 mW m-1 K-2 at 323 K, which is the highest reported for TiS2. The reproducibility of the electrical properties of TiS2 for application at temperatures that do not exceed 473 K was confirmed by a heat-soak experiment. Nanoparticles of TiS2 with controlled morphologies were synthesised using a scalable solution-based route. Measurements of the Seebeck coefficient were carried out on TiS2 nanoflakes and a stoichiometry of Ti1+xS2 where x lies within the range 0.02 ≤ x ≤ 0.03 was determined. The thermoelectric properties of TiS2 nanocomposites with TiO2 nanoparticles and carbon nanotubes (CNTs) were investigated. A 12 % increase in the figure of merit over that of pristine TiS2 at 573 K, ZT = 0.28, is observed for the nanocomposite with 0.5 vol% of nano-TiO2. Two families of copper sulphides were investigated for their promising p-type thermoelectric properties, tetrahedrites, including Cu12-xMnxSb4S13 (x = 0; 1) and Cu12+ySb4S13 (x = 0; 0.3; 1; 1.5 and 2), and manganese-doped bornite, Cu5Fe1-xMnxS4 (0 ≤ x ≤ 0.10). A combination of powder X-ray and neutron diffraction analysis of Cu12-xMnxSb4S13 (x = 0; 1) located the Mn atoms on the Cu(1) site in tetrahedral position. Manganese substitution leads to a substantial reduction in thermal conductivity and the figure of merit is improved with ZT = 0.56 at 573 K. Structural analysis using powder X-ray diffraction and measurements of the thermoelectric properties of a series of copper-enriched tetrahedrite Cu12+ySb4S13 (y = 0.3; 1; 1.5; 2) were carried out. At room temperature, Cu12+ySb4S13 exists as a mixture of a Cu-poor and a Cu-rich phase and a change of behaviour in the electrical and thermal properties are observed over the temperature range 380 ≤ T / K ≤ 410. An increase in the Seebeck coefficient and a simultaneous decrease in the thermal conductivity are responsible for a large improvement in the figure of merit with ZT = 0.62 at 573 K for Cu12+ySb4S13 (y = 1.5 and 2). A manganese-doped bornite series of composition Cu5Fe1-xMnxS4 (0 ≤ x ≤ 0.10) was successfully synthesised using mechanical alloying. This synthetic method offers a simplified route to large scale production as well as better thermoelectric performance (ZT = 0.55 at 543 K) compared with samples prepared by solid-state reaction (ZT ≈ 0.4 at 573 K). Structural investigation was carried out using a combination of powder X-ray diffraction and SEM/EDX analysis and the solubility limit of Cu5Fe1-xMnxS4 was determined to be x = 0.1. Repeated electrical measurements and thermogravimetric analysis were carried out in order to investigate the stability of the samples and the reproducibility of the electrical properties as a function of time and temperature.
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Abedelrasoul, Abuelgasim Abbaker. "Studies on the chemistry of some sulphides and of some sulphur-containing heterocyclic compounds". Thesis, University of Hull, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333763.
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McMordie, Robert Austin Simms. "Synthetic, mechanistic and stereochemical studies of the primary metabolites of sulphides and cyclic hydrocarbons". Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335559.
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Jean, R. N. Maïtena. "Étude de la matte sulfo-oxydante de la mangrove de Guadeloupe : caractérisation des micro-organismes principaux des familles Beggiatoaceae et Oscillatoriaceae". Thesis, Antilles-Guyane, 2013. http://www.theses.fr/2013AGUY0614/document.
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Les mattes de procaryotes constituent une niche écologique diversifiée. peu étudié!<..en mangrove et jamais décrjte dans les Antilles. L'objectif de cette thèse est de décrire les procaryotes filamenteux reposant sur le sédiment marin et de caractériser les interactions entre la matte, milieu et entre les différents micro-organismes. Nous avons d'abord caractérisé les micro-organismes majoritaires de la matte par le séquençage de l'ADNr 16S et des hybridations moléculaires (FISH). Il a ainsi été possible de décrire deux nouvelles espèces de Beggiatoaceae dont la structure a été étudiée par microscopie électronique. De plus, afin de caractériser l'environnement chimique de ces bactéries, des capteurs potentiométriques ont été utilisés. Ils ont permis de démontrer que les Beggiaotaceae oxydaient les sulfures en prélevant l'oxygène du milieu, tandis que des analyses de microscopie couplées à de l'EDX ont mis en évidence des réserves de soufre intracellulaires dans ces bactéries. Le séquençage de l'ADNr 16S des cyanobactéries filamenteuses a mis en évidence quatre nouvelles espèces de l'ord~e des Oscillatoriales. Deux d'entre elles, du genre Planktothricoides ont révélé une toxicité positive sur les Artemia sp:, les deux autres ont été identifiées comme proches d'Oscillatoria spongeliae, une espèce symbiotique d'éponge, bien que les coupes uItrafines d'une de ces souches aient montré une morphologie interne proche des Tychonema. L'analyse des données a permis d'étoffer les connaissances sur les communautés microbiennes de mangrove et constitue une base intéressante de travail sur la contribution des micro-organismes au fonctionnement de l'écosystème mangrove dans son ensembleProcaryotic mats are ecological niches, occuring in many ecosystems. Those structures are little studied in marine mangrove sediment and have never been described in West Indies. The purpose ofthis thesis is to characterize the interactions between the mat and the environment, and between the different filamentous micro-organisms living into the mat. In a first place, we characterized the mainly micro-organisrns of the mat by sequencing 16S rDNA. We confirmed these sequences by molecular hybridization (FISH) with specific probes designed from sequences obtained. Thus, it was possible to describe two new Beggiatoaceae strains, whose structure has been studied by electronic microscopy. Furthemore, we used potentiometric captors in situ and in laboratory, by creating a mesocosm, in order to define the chemical environment where involved these bacteria. These experiences proved that the Beggiatoaceae of the mat oxidized the sulfur taking the oxygen from the medium, while the microscopic analysis coupled with EDX showed intracellular sulfur granules into the bacteria. The study of the filamentous cyanobacteria of the mat highlighted four new cyanobacteria strains, all studied by electronic rmcroscopy. Two of them belongs to Planktothrlcoides genus and showed positive toxicity on Artemia salina. The others species are close to Oscillatorla spongeliae, a sponge symbiont, nevertheless, one ofthem showed an intemal morphology close to Tychonema. The analysis of the different results adduces sorne knowledge about mangrove microbial communities. Furthermore, this study can be used as an interesting base to study the micro-organisms contribution in functioning mangrove ecosystem
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Dasgupta, Jhinuk. "Investigation on some 2-Alkylamido 6-chloro/Nitro-4H-1, 3, 2-Benjodi-oxaphosphorin-2 - Sulphides having pesticidal activities". Thesis, University of North Bengal, 1988. http://hdl.handle.net/123456789/1130.
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Rumball, John Alfred. "The interaction of partially weathered sulphides in the Mt McRae shale formation with ammonium nitrate". Thesis, Rumball, John Alfred (1991) The interaction of partially weathered sulphides in the Mt McRae shale formation with ammonium nitrate. PhD thesis, Murdoch University, 1991. https://researchrepository.murdoch.edu.au/id/eprint/51662/.
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Spontaneous explosion of ANFO charged in partially-weathered sulphides and the spontaneous combustion of these sulphides are serious hazards at the Mt Whaleback mine in the Pilbara region of Western Australia. The potential exists for the problems to become equally serious at Tom Price, Paraburdoo and other iron ore mines operating in the Brockman Iron Formation.
The partially weathered sulphides occur in the Mt McRae Shale Formation, which is stratigraphically below the iron orebody in these mines. Folding and slope stability considerations necessitate the mining of large volumes of this shale to access the stratigraphically younger ore.
The only sulphide mineral of significance in the shales is pyrite. Pyrite occurs as micron sized pyritohedra, nodules, veins and sub-hedral clusters. Graphite exists as a fine-grained, poorly crystalline phase that forms a continuous network imparting high electrical conductivity to the shale. Chert and 10 A sheet silicate minerals are abundant, but appear to be relatively inert.
The shales are strongly acidic (0.6 moles of H+/kg) and contain ferrous sulphates (0.07 moles of FeSO4/kg). These salts are the result of partial oxidation of pyrite deep below the zone of obvious weathering, a process made possible by the electrical conductivity of the shales. The acidic iron sulphates are retained within the shale by adsorption on the graphite.
The spontaneous explosion of ANFO results when AN comes into contact with partially weathered sulphides. A detonation will occur if there is sufficient ANFO confined in an environment such as a stemmed blast-hole.
Spontaneous combustion results from the same series of reactions that initiate an explosion. In this instance, however, the heat from the interaction between the partially weathered sulphides and AN ignites the shale rather than initiating the explosive decomposition of AN. The amount of AN required to initiate spontaneous combustion is dependent on conditions, but may be less than 25 g. Such a small amount of AN may readily accumulate in a mining environment due to the quantity used in blasting and the high mobility of AN.
The reaction between partially weathered sulphides and AN consistently shows four stages:
Initial Stage
Sulphuric acid derived from partial oxidation of pyrite during incipient weathering, interacts with the AN to generate nitric acid, which is reduced to nitrous acid by a slow reduction reaction: NO3- (aq) + 3H+ (aq) + 2e- → HNO2 (aq) +HNO2 (aq) + H2O(1)(Exothermic, ∆H° = -200 kJ mol-1)
Oxidation of ferrous ions adsorbed on graphite completes the redox couple.
This reaction may take place as a galvanic process with reduction and oxidation occurring on cathodes and anodes of graphite.
Intermediate Stage
When nitrous acid reaches a concentration that is sufficient for it to act as a catalyst the rate of the Initial Stage reaction increases dramatically. The nitrous acid formed rapidly oxidises the ferrous ions and pyrite forming nitric oxide, ferric, ferrous and sulphate ions:
HNO2 (aq) + H+(aq) + e- → NO(g) + H2O (1) (Exothermic, ∆H° = -76 kJ mol-1)
Fe2+ (aq) → Fe3+ (aq) + e- (Endothermic, ∆H° = +41 kJ mol-1)
FeS2 (s) + 8H2O(1) → Fe2+ (aq) + 2SO42-(aq) + 16H+(aq) + 14 e- (Endothermic, ∆H° = +557 kJ mol-1)
Although the oxidation reactions are mildly endothermic, the reduction reaction is strongly exothermic, hence the redox pairs generate heat.
Ignition Stage
Nitrogen dioxide, produced from the atmospheric oxidation of nitric oxide, together with nitric oxide and heat initiate the violent exothermic decomposition of AN at temperatures below 100°C:
NH4N03 (s) → N2O (g) + 2H2O (g) (Exothermic, ∆H° = -36 kJ mol-1)
2NH4NO3 (s) → 2N2(g) + O2 (g) + 4H2O (g)
(Exothermic, ∆H° = -236 kJ mol-1)
Combustion Stage
The high temperatures attained by the Ignition Stage cause the pyrite and graphite in the shale to combust generating sulphur dioxide and carbon dioxide respectively:
2FeS2 (s) + 11/2O2(g) → Fe2O3(s) + 4SO2(g)
(Exothermic, ∆H° = -1655 kJ mol-1)
C(s) + O2(g) → CO2 (g)
(Exothermic, ∆H° = -394 kJ mol-1)
Alkali and surfactant chemicals may be used to inhibit the interaction between partially weathered sulphides and AN.
Before they may be used to prevent spontaneous explosions further development is required to blend the inhibitor within prilled, emulsified or slurried AN explosives. Simply mixing the inhibitor with coarsely prilled AN does not reliably inhibit potentially reactive pockets of AN that may be smaller than 25 g. In the interim, tough and durable liners are used at Mt Whaleback to separate physically the partially weathered sulphides and AN.
To minimise spontaneous combustion a slurry of limestone in a short chained anionic sulphonate and water may be applied. The limestone is cheap and easy to handle while the short tail group on the surfactant is water soluble, the anionic head group adsorbs to active cathodic surfaces and the sulphonate is acid resistant.
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Wengorsch, Tobias. "Experimental Alteration in Composite Mineral Systems: Mg-silicates, Fe-Ni-sulphides and Fe-Ti-oxides". Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/78546.
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This study provides new insight into fluid-mediated replacement reactions for three different mineral systems. Hydrothermal experiments were conducted at 150 °C and 240 °C. It was found that serpentinisation reaction kinetics and crystal morphology are dependent on fluid and solid composition. Furthermore, primary Ni-sulphides were transformed into high Ni-tenor assemblages and it was found that the generation of fracture networks within ilmenite is strongly affected by the presence of hematite.
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Madureira, Danielle Jannuzzi. "Analise da expressão de genes que codificam proteinas transportadoras em Acidithiobacillus ferrooxidans e Acidithiobacillus thioxidans na presença de sulfetos metalicos". [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/316929.
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Orientadore: Laura Maria Mariscal Ottoboni, Fernanda de Castro ReisDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Acidithiobacillus ferrooxidans e Acidithiobacillus thiooxidans são espécies bacterianas acidofilicas, quimiolitotróficas e mesofilicas, encontradas em ambientes de biolixiviação. A. ferrooxidans utiliza íons ferrosos e compostos que contém enxofte como doadores de elétrons enquanto que A. thiooxidans utiliza apenas enxofte e compostos contendo enxofte. Ambas as espécies utilizam principalmente o oxigênio como receptor final de elétrons, contudo, podem também crescer em ambientes de anaerobiose. A. thiooxidans possui maior resistência ao pH podendo ser encontrada em ambientes com pH variando de 0,5 a 5,0, enquanto que A.ferrooxidans é encontrada em pHs que variam de 1,0 a 2,5. Devido a essas características e devido a capacidade dessas bactérias de solubilizar metais, A. ferrooxidans e A. thiooxidans vem sendo utilizadas em experimentos de biolixiviação. Este processo é utilizado na indústria para recuperação de cobre devido às vantagens oferecidas. Entretanto, pouco se sabe sobre a resposta gênica destas bactériaS a presença de sulfetos metálicos e dos metais pesados em solução proveniente do processo de oxidação. Na primeira parte deste trabalho foi analisada a resposta gênica da estirpe de A. ferrooxidans LR na presença e na ausência de covelita (CuS) por 24 horas através da técnica de RAP-PCR (Random Arbitrarily Primed Polymerase Chain Reaction). Foram obtidos 19 cDNAs com expressão diferencial, dos quais 12 foram confirmados como sendo diferencialmente expressos. Dentre estes, foram isolados sete genes que codificam: proteínas de transporte (AFE 0123, AFE ,0989, AFE 0990, AFE 0580, AFE 0671, AFE 2248 e AFE 1149), a proteína diguanilato ciclase, uma proteína de membrana, uma metiltnmsferase e uma ATPase, todas induzidas na presença da covelita. Apenas o gene infC, que codifica um fator de iniciação de tradução tipo 3, teve sua expressão reprimida na presença de covelita. Como sete dos genes diferencialmente expressos pertenciam à classe de transportadores, foram investigadas às modificações químicas presentes no meio de cultura após 24 horas. Análises de absorção atômica mostraram que a quantidade de' co1?rê em solução inicialmente zero passava para aproximadamente 1,13 g/L e medidas de pH mostraram que após este período de tempo houve mudanças de 1,8 para 4,0. Pode-se sugerir que essas alterações químicas sejam responsáveis, pelo menos em parte, pela indução dos genes que codificam proteínas de transporte. Uma análise in silico da interação entre proteínas (PPI) relacionadas com transporte, cujos genes foram diferencialmente expressos na presença de covelita e de proteínas pertencentes à mesma categoria funcional, codificadas por genes que estavam fisicamente localizados nas proximidades dos genes diferencialmente expressos, mostraram que os genes de transporte podem estar envolvidos em diferentes etapas da resposta bacteriana à presença de covelita. A segunda parte deste trabalho teve como objetivo estudar a expressão diferencial, por PCR em tempo real, de duas proteínas do tipo ABC (AFE 0123 e AFE 0125) e uma proteína do tipo RND (AFE 0993) na estirpe de A. thiooxidans FGOl na presença de calcopirita (CuFeS2), covelita e pirita (FeS2) por 24 horas. Para tal, a estirpe foi crescida na presença de enxofte e depois mantida na presença dos sulfetos metálicos por 24 horas. A expressão dos três genes foi induzida na presença de covelita e inalterada na presença de calcopirita. Na presença de pirita, a expressão de dois genes foi reprimida e do gene AFE 0993, permaneceu inalterada. Estes resultados podem ser explicados, pelo menos em parte, pelas quantidades de cobre encontradas em solução na presença de covelita (l g/L) e na presença de calcopirita (0,07 g/L). Na presença de covelita e calcopirita a medida de pH também softeu aumento de 1,8 para 4,0 e 2,5, respectivamente. Para investigar se a alteração de pH ou a presença de íons de cobre eram os responsáveis pela indução da expressão desses genes, a bactéria foi mantida na presença de sulfato de cobre (16 mM) e pH 4,0 por 24 horas. Os resultados mostraram que a presença de cobre em solução induz a expressão destes genes, enquanto que a alteração do pH não
Abstract: Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans are acidophilic, chemolitotrophic and mesophilic bacteria found in bioleaching environments. A. ferrooxidans uses ferrous iron and sulphur compounds as an e1ectron donor and A. thiooxidans uses on1y sulphur and sulphur compounds. Both species are aerobic using oxygen as final e1ectron acceptor. However, these bacteria are also able to grow in anaerobic environments. A. thiooxidans is able to survive in pHs ranging from 0.5 to 5.0 while A. ferrooxidans grows in pHs from 1.0 to 2.5. Due to these characteristics and the ability of these bacteria to solubilize metal sulphides, A. ferrooxidans and A. thiooxidans are used in bioleaching. This process has several advantages over the traditional methods and has been used with success in industrial operations to recover main1y copper. However, little is known about the genetic response of these bacteria to the presence of metal sulphides and heavy metal in solution. Therefore, in the first part of this study the A. ferrooxidans LR 'response to covellite was investigated. This bacterium was maintained in contact with covellite for 24 hours and the differentially expressed cDNAs were identified by RAP-PCR (Random Arbitrarily Primed Polymerase Chain Reaction) technique. Nineteen cDNAs showed a differential expression and twe1ve had their differential expression confirmed by real time PCR. Among these cDNAs, seven codified for transporter proteins (AFE 0123, AFE 0989, AFE 0990, AFE 0580, AFE 0671, AFE 2248 and AFE 1149), one codified for a putative diguanylate cyc1ase, one for a membrane. protein, one for a methyltransferase and one for an A TPase. With the exception of infC whose expression was down regulated, all the oDNAs had their expression up regulated in the presence of covellite. Since most of the differentially expressed genes are involved in transport, chemical modifications on the culture medium after 24 hours were investigated. The atomic absorption analysis showed that the copper amount in solution was 1.13 g/L and pH changed from 1.8 to 4.0 suggesting that these changes are responsible, at least in part, for the induction,"?f1he expression of transport gene. An in si/ico ana1ysis of protein-protein interaction (PPI) between the transport proteins codified by the genes differentially expressed in the presence of covellite and those codified by genes that were physically located around the differentially expressed ones showed that these transport proteins could be involved in different steps of the bacterial response to covellite. The goal of the second part of this study was to analyse the differential expression, by real time PCR, of two ABC proteins (AFE 0123 andAFE 0125) and one RND protein (AFE 0993) inA. thiooxidans FGOl in the presence of chalcopyrite, covellite and pyrite for 24 hours. This strain was maintained in contact with the metal sulphides for 24 hours. The expression ofthe three genes was up regulated in the presence of covellite and unchanged in the presence of chalcopyrite. In the presence of pyrite two genes hOO their expression down regulated and in one (AFE 0993) the expression was unchanged. These results can be explained, at least in part, by the quantities of copper found in solution in covellite (1 g/L) and in chalcopyrite (0.07 g/L). In the presence of covellite and chalcopyrite the pH changed from l'.8 to 4.0 and 2.5, respectively. To investigate if the changes in pH or the presence of copper ions in solution were responsible for the induction of the gene expressions, the bacteria were maintained in the presence of copper sulphate (16 mM) and pH 4.0 for 24 hours. The results showed that the presence of copper in solution was the responsible for the up regulation ofthese genes
Mestrado
Biologia Celular
Mestre em Genética e Biologia Molecular
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Almeida, Carolina Michelin de. "Gênese dos corpos de sulfeto maciço hidrotermal e platinóides associados no depósito de Fortaleza de Minas (MG) /". Rio Claro : [s.n.], 2003. http://hdl.handle.net/11449/92912.
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Orientador: Sebastião Gomes de CarvalhoBanca: Antenor Zanardo
Banca: João Batista Moreschi
Resumo: A mineralização sulfetada de Ni-Cu-Co (PGE), associado a rochas komatiíticas, da Jazida de Fortaleza de Minas, no sudoeste do Estado de Minas Gerais é tido como de origem magmática, porém processos pós-magmáticos modificaram substancialmente a distribuição original, estrutura, textura, mineralogia e química dos minérios. Estão presentes três importantes tipos de minérios sulfetados mobilizados: brecha, formação ferrífera bandada (BIF) e minério maciço hidrotermal. O último, é o objeto de estudo desta pesquisa. O minério maciço hidrotermal está associado a zonas de falhas transversais tardias, de direção NE-SW e N-S que cortam as rochas hospedeiras, e são perpendiculares a principal zona de cisalhamento que contém o principal corpo de minério. O minério maciço hidrotermal é formado por uma matriz oxi-sulfetada, constituída por pirrotita, pentlandita, calcopirita, pirita, violarita e magnetita, contendo minerais da série cobaltita-gersdorffita, minerais do grupo da platina, minerais da série linneita-polidymita, siegenita, além de carbonatos e quartzo. Os minerais do grupo da platina ocorrem disseminados por todo minério, associados a fases silicáticas hidratadas, inclusos em grãos de magnetita e minerais da série cobaltita-gersdorffita, no contato entre o minério e as rochas encaixantes. Próximo ao contato, são observados típicas feições de alteração hidrotermal do tipo talco-carbonato-clorita-sulfeto. Ao final do evento tectono-metamórfico, durante o Neo Proterozóico, que atuou na área em condições de baixa a alta temperatura (fácies xisto verde), foram produzidas diversas soluções hidrotermais que afetaram as rochas encaixantes nas proximidades do corpo de minério, bem como do próprio minério, originando um novo tipo de minério, aqui designado como minério maciço hidrotermal.
Abstract: The komatiite-associated Ni-Cu-Co (PGE) sulphide mineralization at Fortaleza de Minas, southwestern of Minas Gerais state is believed to have a magmatic origin, but a number of post-magmatic processes significantly modified the original distribution, structure, texture, mineralogy and chemistry of the ores. Three important types of mobilized sulphide are present: breccia, banded iron formation (BIF) and hydrothermal massive ore. The last is the object of study of this research. The hydrothermal massive ore are associated to the late transversal fault zones, of N-S and NE-SW direction that cut host rocks, and are perpendicular to the principal shear zone that comprise the main ore body. The hydrothermal massive ore is formed by a massive oxi-sulphated matrix, consisted of pyrrhotite, pentlandite, chalcopyrite, pyrite, violarite and magnetite, comprising cobaltite-gersdorffite minerals series, platinum-group minerals, linnaete-polydymite minerals series, siegenite, besides carbonates and quartz. The platinum-group minerals occur disseminated over the entire ore, associated to hydrated siliceous phases, and enclosed in magnetite grains and cobaltite-gersdorffite mineral series, in the contact between the ore and enclosing rocks. Next to this contact, are observed typical hydrothermal alteration features as talc-carbonate-chlorite-sulphide. In the end of the tectonic-metamorphic event, during the Neo Proterozoic, that actuated in the area in conditions of low to medium temperatures (greenschist facies), were produced a number of hydrothermal solutions that affected enclosing rocks next to the ore body as well as the proper ore, generating a new type of ore, here designated as hydrothermal massive ore.
Mestre
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MacRobbie, Paul Alexander Carleton University Dissertation Geology. "Stratigraphy, structure and volcanogenic sulphides, in Sicker group volcanic rocks on Mt. Sicker, Vancouver Island, B.C". Ottawa, 1988.
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Hagerfors, Erika. "Formation of Sulphides in the Canadian High Arctic Large Igneous Province; Testing the Influence of Sedimentary Rocks". Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-357415.
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Large Igneous Provinces (LIPs) form during short-lived pulses of extensive magmatic activity. LIPs are known for their ability to affect global climate as well as for their Ni-Cu-PGE ore potential. A key factor that controls the intensity of the climate impact of a LIP and its ore potential is the assimilation of volatile-rich sedimentary host rocks. Magmas of the High Arctic Large Igneous Province (HALIP), exposed in the Arctic, intruded volatile-rich black shales, carbonates and evaporites in the Canadian Arctic Islands, offering a great opportunity for studying magma-sediment interaction. The purpose of this study is to test whether assimilation of sedimentary sulphide can promote sulphide immiscibility in magma and thus aid formation of Ni-Cu-PGE ore bodies. This is done by analysing sulphur isotopes in pyrite grains hosted in a HALIP dolerite sill, which was emplaced into black shale, by using Secondary Ion Mass Spectrometry (SIMS). Four dolerite samples are analysed; two coming from the lower contact margin of the sill, one from 60 cm into the sill and one sample from a basaltic vein at the upper contact margin of the sill. A total of 14 pyrite grains (n = 246 individual SIMS spot analyses) were analysed for their sulphur isotope ratios. The results of the SIMS analyses show that all analysed sulphides have highly negative δ34S values ranging from -19.5 to -5.7‰ (average δ34S = -8.2 ± 0.83‰, 2SD), which therefore differ largely from that of the primitive mantle (0 ± 1.8‰). In order to put our four analysed dolerite samples into a broader context, δ34S data of our sulphides are compared with whole-rock δ34S and δ18O data from Hare Fiord shale and dolerite samples. The δ34S values of the sulphide samples from the sill typically trend toward the negative sulphur isotope composition of the sulphides in the surrounding shale, and the shale surrounding the sill experiences a loss of 32S near the contact of the sill. This indicates that sedimentary light sulphur (32S) has been locally incorporated into the sill by the surrounding shale, resulting in negative δ34S values in the magmatic sulphides. Since sulphide immiscibility in the Hare Fiord sill was triggered by assimilation of sulphur from host rock shale, the igneous rocks of the HALIP may be prospective for Ni-Cu-PGE mineralization, though more studies are needed. Furthermore, our results suggest that incorporation of crustal sulphur increased the volatile budget of HALIP magmas, which therefore could have contributed to a deterioration of the environmental conditions during the emplacement of the HALIP.Stora magmatiska provinser (på engelska Large Igneous Provinces, LIPs) är vulkaniska event då enorma mängder magma avsätts över en väldigt stor yta under ett, i ett geologiskt perspektiv, kort tidsspann. Dessa stora vulkaniska utbrott har väckt stort intresse då de är samtida med flera av de största massutdöendena i jordens historia, men också för att en viss typ av sulfidmalm rik på nickel, koppar och platinametaller (Ni-Cu-PGE malmer) ofta förekommer i provinsernas magmagångar och magmakammare. En viktig faktor som till stor del avgör en magmatisk provins påverkan på klimatet och potentiella malmförekomster är inkorporering av sedimentära bergarter till magman som, när de hettas upp, kan frigöra gaser rika på svavel och kol. I Kanadas arktiska öar trängde magma tillhörande den högarktiska magmatiska provinsen (HALIP) in i svart skiffer, karbonater och evaporiter, som är sedimentära bergarter rika på flyktiga ämnen. Denna magmatiska provins erbjuder därför stora möjligheter till att studera interaktionen mellan magma och sedimentära bergarter. Syftet med denna studie är att testa om inkorporering av sedimentärt svavel kan främja bildandet av sulfidsmälta i magma och därigenom bidra till bildandet av sulfidmalmer. Detta görs genom att analysera svavelisotoper i sulfidmineral i prover från en magmagång, som trängde in i en skifferformation, tillhörande den högarktiska magmatiska provinsen i norra Kanada. Genom att analysera svavelisotopkvoten (δ34S) i sulfidmineral kan man få information om huruvida svavlet i mineralen är av sedimentärt ursprung (där skiffer generellt har negativa δ34S värden) eller om svavlet har δ34S värden liknande de från manteln (som har δ34S värden runt 0‰), vilket i så fall skulle innebära att magman inte har inkorporerat sedimentärt svavel. Genom att använda masspektrometri av typen SIMS analyseras totalt 14 sulfidmineralkorn (n = 246 individuella SIMS punkter) för deras svavelisotopkvoter. Resultatet av studien visar att alla analyserade sulfidmineral har mycket negativa δ34S värden mellan -19.5 och -5.7‰ (med ett δ34S medelvärde på -8.2 ± 0.83‰, två standardavvikelser). Genom att jämföra våra δ34S värden med δ34S och δ18O värden för andra prover från både magmagången och den omgivande skiffern kunde vi se att δ34S värdena för sulfidmineralen i de yttre delarna av magmagången har liknande negativa värden som den omgivande skiffern, och att δ34S värdena för skiffern närmast magmagången är mer positiva. Detta tyder på att sedimentärt svavel i kontakten mellan magmagången och skiffern har blivit inkorporerat i magman från den omgivande skiffern. Våra resultat tyder därför på att sulfidmineralen i våra prover från magmagången bildades genom assimilering av svavel från den omgivande skiffern. Detta innebär i sin tur att den kanadensiska högarktiska magma provinsen potentiellt kan vara en källa för sulfidmalm, även om ytterligare studier behövs. Dessutom visar våra resultat att inkorporering av sedimentärt svavel förmodligen ökade de vulkaniska gaserna i magman, vilket kan ha bidragit till klimatförändringar relaterade till den vulkaniska aktiviteten av den högarktiska magmatiska provinsen.
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Lindeberg, Tomas. "Indium Analysis and Small-scale Distribution in Sulphides from the Lindbom Prospect, Långban Area, Western Bergslagen Ore Province". Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-196479.
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Indium is extensively used in LCD screens and solar cells. It is mainly produced as a byproduct during ore processing. With ever increasing demand for indium and most of the production being restricted to a few countries new sources for indium are needed. In Sweden, the westernmost Bergslagen is the only area, which is known to exhibit minerals with essential indium. The indium mineralisations at Långban, the Linbom prospect, which are studied in this bachelor’s thesis show several trends. The most notable is the copper indium trend seen in sphalerite. A likely substitution based on similar ionic radii and charges is Cu1++ In3+ ↔ 2Zn2+.Usually when cassiterite is associated with similar polymetalic indium bearing mineralisations as at Långban there is also high concentrations in cassiterite. This has previously not observed in Sweden, however during this project concentrations were indeed found in cassiterite.
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Missack, Evon A. "Mineralogy and phase relations of the massive sulphides and metalliferous sediments of the Axial Rift Valley, Red Sea /". Heidelberg : [Ruprecht-Karls-Universität], 1988. http://catalogue.bnf.fr/ark:/12148/cb37429905t.
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