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Academic literature on the topic 'Sulfur and iron reduction'

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Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "Sulfur and iron reduction"

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Rezaee, Bahram, Atefe Sarvi, Atiyeh Eslamian, Seyed MehdiJebraeeli, and Abolfazl Zabihi. "Sulfur reduction in Sangan iron ore by flotation." E3S Web of Conferences 18 (2017): 01023. http://dx.doi.org/10.1051/e3sconf/20171801023.

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in this study the flotation of pyrite as the main sulfide impurity of Sangan iron ore in Iran, was investigated. For this purpose the effect of collector type, pH, collector concentration and stage dosing on reverse flotation of iron sulfide ore from magnetite ore was investigated. Two type of thiol collectors include xanthates (sodium isopropyl xanthate (SIPX) and potassium amyl xanthate (PAX)) and dithiocarbamate (di-ethyl dithiocarbamate (DTC)) and the mixture of collectors was studied. The highest sulfur removal was obtained with potassium amyl xanthate. Stage dosing had a significant effect in sulfide flotation and the best recovery was obtained when the collector was added in 4 stages. The acidity had a positive effect on sulfide floatability and the best result was obtained at pH 3.5-4. Investigation about collector concentration showed that increasing the SIPX concentration enhanced the sulfur removal but this factor was not effective for PAX.
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Cammack, Richard. "Iron–sulfur proteins." Biochemist 34, no. 5 (October 1, 2012): 14–17. http://dx.doi.org/10.1042/bio03405014.

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Iron makes up 35% of the Earth's mass, and is plentiful in its crust (approximately 5%), so it is not surprising that Biology has found many different applications for it. Iron–sulfur (Fe–S) clusters are essential, ubiquitous inorganic cofactors in electron-transport proteins of respiration and photosynthesis, and are responsible for the activity of hundreds of enzymes1. Various types of clusters (Figure 1) occur in iron-sulfur proteins, bound covalently to protein ligands, usually cysteine sulfur. Their activity is not confined to oxidation/reduction; in enzymes such as aconitase, they are involved in substrate binding and conversion. Fe–S enzymes that catalyse difficult reactions, such as nitrogenase in nitrogen fixation and hydrogenase in hydrogen production, contain complex ‘superclusters’2.
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Straub, Kristina L., and Bernhard Schink. "Ferrihydrite-Dependent Growth of Sulfurospirillum deleyianum through Electron Transfer via Sulfur Cycling." Applied and Environmental Microbiology 70, no. 10 (October 2004): 5744–49. http://dx.doi.org/10.1128/aem.70.10.5744-5749.2004.

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ABSTRACT Observations in enrichment cultures of ferric iron-reducing bacteria indicated that ferrihydrite was reduced to ferrous iron minerals via sulfur cycling with sulfide as the reductant. Ferric iron reduction via sulfur cycling was investigated in more detail with Sulfurospirillum deleyianum, which can utilize sulfur or thiosulfate as an electron acceptor. In the presence of cysteine (0.5 or 2 mM) as the sole sulfur source, no (microbial) reduction of ferrihydrite or ferric citrate was observed, indicating that S. deleyianum is unable to use ferric iron as an immediate electron acceptor. However, with thiosulfate at a low concentration (0.05 mM), growth with ferrihydrite (6 mM) was possible and sulfur was cycled up to 60 times. Also, spatially distant ferrihydrite in agar cultures was reduced via diffusible sulfur species. Due to the low concentrations of thiosulfate, S. deleyianum produced only small amounts of sulfide. Obviously, sulfide delivered electrons to ferrihydrite with no or only little precipitation of black iron sulfides. Ferrous iron and oxidized sulfur species were produced instead, and the latter served again as the electron acceptor. These oxidized sulfur species have not yet been identified. However, sulfate and sulfite cannot be major products of ferrihydrite-dependent sulfide oxidation, since neither compound can serve as an electron acceptor for S. deleyianum. Instead, sulfur (elemental S or polysulfides) and/or thiosulfate as oxidized products could complete a sulfur cycle-mediated reduction of ferrihydrite.
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Zhang, Rui Yong, Sabrina Hedrich, and Axel Schippers. "Reduction of Iron(III) Ions at Elevated Pressure by Acidophilic Microorganisms." Solid State Phenomena 262 (August 2017): 88–92. http://dx.doi.org/10.4028/www.scientific.net/ssp.262.88.

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A composed mixed acidophilic, iron-oxidizing culture (FIGB) and a thermo-acidophilic enrichment culture (TK65) were used to evaluate microbial iron(III) reduction coupled to oxidation of reduced inorganic sulfur compounds (RISCs) under high pressure. Experiments were done in batch culture in high pressure vessels at 1 and 100 bar. Microbial abundance and activity were determined by measuring iron(II) concentration, direct cell counting, T-RFLP and quantitative real-time PCR. The data indicate that both cultures are able to reduce soluble iron(III) by oxidation of sulfur compounds under anaerobic conditions. At high pressure (100 bar) these acidophiles were capable of growing and microbial ferric iron reduction was only partially inhibited. These results indicate that acidophiles can be barotolerant and their activities are contributing to sulfur and iron cycling in anaerobic environments including deep ore deposits which is highly relevant for in situ leaching operations.
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Zulhan, Zulfiadi, Zhahrina Adzana, Mona Munawaroh, Achmad Haerul Yusro, Jonathan Dwiputra Christian, Aura Dwi Saputri, and Taufiq Hidayat. "Sulfur Removal and Iron Extraction from Natrojarosite Residue of Laterite Nickel Ore Processing by Reduction Roasting." Metals 13, no. 1 (December 24, 2022): 52. http://dx.doi.org/10.3390/met13010052.

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An alternative laterite nickel ore processing using sulfuric acid as a leaching agent to produce class 1 nickel as a raw material for electric vehicle batteries produces natrojarosite residue as a by-product during the precipitation of iron and aluminum step. The natrojarosite residue contained iron and high sulfur, which is challenging to utilize as an iron source for steel manufacturing since sulfur can contaminate the steel product. This study focuses on sulfur elimination and iron extraction from natrojarosite. The natrojarosite was roasted for sulfur removal isothermally at different temperatures ranging from 500 until 1100 °C for 4 h. Roasting at 1100 °C resulted a decrease in sulfur content from 12.18% to 3.81% and an increase in iron content from 16.23% to 28.54%. The sulfur released during roasting can, in principle, be recirculated to a sulfuric acid plant and reused as a leaching agent in the nickel ore processing plant. The unroasted and roasted natrojarosite residues were then reduced by coconut shell charcoal in the temperature range of 1000–1400 °C. The results showed that the metallic iron could be obtained from both unroasted and roasted natrojarosite residue at a temperature of 1200 °C and higher. The sulfur content in the oxide phase of unroasted natrojarosite residue was significantly higher than roasted natrojarosite residue. However, the roasting did not significantly influence the sulfur content in the metal phase. The sulfur content in the metal phase from unroasted and roasted natrojarosite residue was less than 1.2%. This result indicated that the removal of sulfur and metal oxide reduction in the natrojarosite residue could be carried out simultaneously in one stage where the natrojarosite residue is reduced by carbonaceous material at a temperature of 1200 °C or higher.
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Kupka, Daniel, Mark Dopson, and Olli H. Tuovinen. "Sulfur Oxidation and Coupled Iron Reduction at Low Temperatures." Advanced Materials Research 20-21 (July 2007): 584. http://dx.doi.org/10.4028/www.scientific.net/amr.20-21.584.

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The purpose of this work was to characterize elemental sulfur oxidation by a psychrotrophic Acidithiobacillus ferrooxidans culture that originated from an AMD-impacted surface soil in a permafrost area in northern Siberia. In this work, the iron-oxidizing culture was cultivated with elemental sulfur with and without Fe2+ or Fe3+ in flasks on a shaker to avoid oxygen limitation.
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Deng, Jiu Shuai, Shu Ming Wen, Shao Jun Bai, Mei Fang Xie, and Hai Ying Shen. "Sulfur Content Reduction and Iron Grade Improvement of V-Ti Magnetite Concentrate by Combining Reverse Flotation and Magnetic Separation." Advanced Materials Research 524-527 (May 2012): 1115–23. http://dx.doi.org/10.4028/www.scientific.net/amr.524-527.1115.

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For low-grade iron ore, smelting costs and resource wastage will be increased. Product quality of such ore is affected adversely by an excessive amount of sulfur. This also causes environmental pollution. In accordance with the vanadium-titanium (V-Ti) magnetite concentrate properties with low iron grade and high sulfur content, the joint process of magnetic separation and flotation was carried out. Magnetic separation was conducted to increase the iron grade, while reverse flotation was used to reduce sulfur content. Results show that the feeding mainly contains titanomagnetite, hematite, and pyrite. The sulfur was primarily found in pyrite. The separation effect was influenced by the grinding fineness, magnetic intensity, collector type and dosage, and pH value. At a grinding fineness of −45 μm accounting for 87%, most of the iron minerals exhibited monomer dissociation. An open-circuit experiment was carried out under the best conditions of magnetic intensity, as well as collector and modifier dosage. Good experimental results were obtained as follows: the iron grade increased to 57.17%, iron recovery was 89.94%, sulfur content decreased from 0.66% to 0.26%, reverse flotation of sulfur foam concentrate contained almost 15.68% sulfur, the upgrade ratio was about 23, and the cobalt in the sulfur concentrate was enriched 20-fold. A method for improving the comprehensive utilization level and effect of mineral resources is provided in this study.
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Rezaee, Bahram, Atefe Sarvi, Atiyeh Eslamian, Seyed MehdiJebraeeli, and Abolfazl Zabihi. "Sulfur reduction in Sangan iron ore by flotation." E3S Web of Conferences 18 (2017): 01023. http://dx.doi.org/10.1051/e3sconf/201712301023.

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Flynn, T. M., E. J. O'Loughlin, B. Mishra, T. J. DiChristina, and K. M. Kemner. "Sulfur-mediated electron shuttling during bacterial iron reduction." Science 344, no. 6187 (May 1, 2014): 1039–42. http://dx.doi.org/10.1126/science.1252066.

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Li, Zhengyao, Jinzhi Wei, Na Liu, Tichang Sun, and Xuewen Wang. "Effect and Mechanism of CaO on Iron Recovery and Desulfurization by Reduction Roasting-Magnetic Separation of High-Sulfur Cyanide Tailings." Minerals 12, no. 2 (February 12, 2022): 239. http://dx.doi.org/10.3390/min12020239.

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The increasing demand for iron ore in the world causes the continuous exhaustion of mineral resources. The utilization of iron in secondary resources has become of focus. The present study was carried out to recover iron from high-sulfur cyanide tailings by coal-based reduction roasting-magnetic separation. The mechanism of CaO to increase iron recovery and reduce sulfur was investigated by observing CO and CO2 gas composition produced by the reaction, mineral composition and microstructure, distribution characteristics of sulfur, and the intercalation relationship between iron particles and gangue minerals. The results showed that the addition of CaO could increase the gasification rate of the reducing agent, increase the amount of CO2 gas produced, promote the reduction of iron minerals, and improve the metallization degree of iron. When CaO was not added, sulfur was mainly transformed into troilite, which was closely connected with iron particles and was difficult to remove by grinding and magnetic separation. With the addition of CaO, CaO preferentially formed oldhamite with active sulfur, which reduced the formation of troilite. Oldhamite was basically distributed in an independent gangue structure. There was a clear boundary between iron particles and gangue minerals. Oldhamite could be removed by grinding-magnetic separation.
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Dissertations / Theses on the topic "Sulfur and iron reduction"

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Theisen, Roslyn Marie. "Synthetic models and reactivity of sulfur-ligated iron metalloenzymes /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/11585.

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Cooper, Rebecca Elizabeth. "Bacterial iron and manganese reduction driven by organic sulfur electron shuttles." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54894.

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Dissimilatory metal-reducing bacteria (DMRB) play an important role in the biogeochemical cycling of metals. DMRB are unique in that they possess the ability to couple metal reduction with their metabolism. Microbial Fe(III) respiration is a central component of a variety of environmentally important processes, including the biogeochemical cycling of iron and carbon in redox stratified water and sediments, the bioremediation of radionuclide-contaminated water, the degradation of toxic hazardous pollutants, and the generation of electricity in microbial fuel cells. Despite this environmental and evolutionary importance, the molecular mechanism of microbial Fe(III) respiration is poorly understood. Current models of the molecular mechanism of microbial metal respiration are based on direct enzymatic, Fe(III) solubilization, and electron shuttling pathways. Fe(III) oxides are solid at circumneutral pH and therefore unable to come into direct contact with the microbial inner membrane, these bacteria must utilize an alternative strategy for iron reduction. Reduced organic compounds such as thiols are prominent in natural environments where DMRB are found. These thiol compounds are redox reactive and are capable of abiotically reducing Fe(III) oxides at high rates S. oneidensis wild-type and ΔluxS anaerobic biofilm formation phenotypes were examined under a variety of electron donor-electron acceptor pairs, including lactate or formate as the electron donor and fumarate, thiosulfate, or Fe(III) oxide-coated silica surfaces as the terminal electron acceptor. The rates of biofilm formation under the aforementioned growth conditions as well as in the presence of exogenous thiol compounds indicate that ∆luxS formed biofilms at rates only 5-10% of the wild-type strain and ∆luxS biofilm formation rates were restored to wild-type levels by addition of a variety of exogenous compounds including cysteine, glutathione, homocysteine, methionine, serine, and homoserine. Cell adsorption isotherm analyses results indicate that wild-type is can attach to the surface of hematite particles attachment , but ΔluxS is unable to attach the hematite surfaces. These results indicate that biofilm formation is not required for Fe(III) oxide reduction by S. oneidensis ∆luxS anaerobic biofilm formation rates were restored to wild-type levels by addition of exogenous auntoinducer-2 (AI-2), a by-product of homocysteine production in the Activated Methyl Cycle. This discovery led to subsequent experiments performed to detect the production and utilization of AI-2 by wild-type and ∆luxS strains under aerobic and anaerobic conditions. AI-2 production experiments showed wild-type, but not ΔluxS, was capable of producing AI-2. The addition of exogenous S. oneidensis and Vibrio harveyi-produced AI-2 to wild-type and ∆luxS resulted in the swift depletion of AI-2 from the media. These results provide evidence that S. oneidensis can produce AI-2 and subsequently utilize its’ own AI-2 as well as AI-2 produced by other bacteria as a carbon and electron source in the absence of preferred carbon sources. S. oneidensis produces and secretes a suite of extracellular thiols under anaerobic Fe(III)-reducing and Mn(III) and Mn(IV)-reducing conditions including cysteine, homocysteine, glutathione, and cyteamine. Exogenous thiols produced by S. oneidensis are intermediates of the Activated Methyl Cycle (AMC) and Transulfurylation Pathway (TSP). Reduced and oxidized thiols were detected, indicating that the thiols are in a constant state of flux between the reduced and oxidized forms and that the concentration of reduced thiols to its’ oxidized counterpart is indicative of the state of metal reduction by the microorganisms. Respiratory phenotypes Based on Fe(III) and Mn(IV) respiratory phenotypes observed in the AMC and TSP pathway mutants (∆luxS, ∆metB, ∆metC and ∆metY) we can infer that cysteine, glutathione, and cysteamine contribute to metal reduction by serving as efficient electron shuttling molecules, while homocysteine is critical for maintenance of the AMC, propagation of thiol biosynthesis, and maintenance of cellular metabolism via the AMC intermediate SAM. Furthermore, these findings suggest that all metal-reducing bacteria require thiol formation to reduce solid metal oxides. Direct contact mechanism is not the dominant means through electrons are transferred and metals are reduced, instead electron shuttles are the maid reduction mechanism.
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Biley, Chris. "Thermodynamic and kinetic modelling of iron (III) reduction with sulfur dioxide gas." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97120.

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Thesis (PhD)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Recent developments in the atmospheric treatment of low-grade nickel laterite ores at Anglo American plc has culminated in the conceptual iron-focused laterite (ARFe) process. In addition to the recovery of nickel and cobalt from laterite ore, this process uniquely aims to recover iron as a saleable by-product. The reduction of soluble iron(III) (Fe(III)) by sulfur dioxide gas (SO2) is central to the ARFe concept and represents a complex, multiphase system involving simultaneous gas-liquid mass transfer, thermodynamic speciation and chemical reaction. The chemistry of iron-containing systems is generally poorly understood and accurately predicting their behaviour is challenging, especially under aggressive hydrometallurgical conditions. The primary objective of this work is the development of an engineering model capable of describing the rate and extent of ferric reduction with SO2 under conditions typical of the ARFe process. Thermodynamic considerations provide a rigorous framework for the interpretation of chemical reactions, however little experimental data are openly available for the associated solution species in acidic iron sulfate systems. A key contribution of this work, and critical for the development of the overall model, is the direct measurement of speciation in iron sulfate solutions. Raman and UV-vis spectroscopy were utilised to make direct speciation measurements in the various subsystems of the Fe2(SO4)3-FeSO4-H2SO4-H2O system that were previously unavailable in the open literature. The FeSO+4 and Fe(SO4)– 2 species were explicitly identified and measurements were supported and rationalised by static computational quantum mechanical calculations and ultimately permit the calibration of a robust, ion-interaction solution model with the explicit recognition of the important solution species up to 1.6 mol/kg Fe2(SO4)3, 0.8 mol/kg H2SO4 over 25 – 90 C. Batch and continuous Fe(III) reduction kinetics were measured and the effects of initial Fe2(SO4)3 and H2SO4 concentrations, temperature and in-situ neutralisation quantified. The retardation effect of sulfuric acid was observed to be the most significant factor influencing the initial reaction rate and the achievable extent of reduction at fixed residence time, which varied between about 20 and 80 % after 180 minutes of reaction. A reaction mechanism that is limited by the slow ligand-to-metal electron transfer in the FeIIISO+3 solution species’ decomposition is proposed and spectroscopic measurements and computational quantum mechanical calculations are used to support this mechanism. A kinetic model, comprising a system of differential mass-balance equations, is incorporated into the thermodynamic framework. This reaction model permits the prediction of kinetic profiles over the full range of experimental conditions and can be incorporated into more elaborate simulation models of the ARFe circuit. The specific original contributions of this work are • The direct measurement of aqueous speciation in the Fe2(SO4)3-H2SO4-H2O system by Raman and UV-vis spectroscopy • The development of a modelling framework to characterise speciation, activity coefficients and solubility in the mixed Fe2(SO4)3-FeSO4-H2SO4-H2O system. • The measurement of Fe(III) reduction kinetics using SO2 in concentrated sulfate solutions as a function of initial composition and temperature. • The development of a solution reaction model of Fe(III) reduction with SO2 that accurately predicts the solution speciation and reaction rate with time as a function of composition and temperature. Lastly, the vast complexity of industrial systems will nearly always result in a lack of specific experimental data that are required for the development of phenomenological models. This work emphasises the crucial role that engineering studies hold in the generation of such data to derive maximum practical value for industrial process development and optimisation.
AFRIKAANSE OPSOMMING: Onlangse ontwikkelinge in die atmosferiese behandeling van lae-graad nikkel lateriet erts by Anglo American plc het gelei tot die konseptuele yster gefokus lateriet (ARFe) proses. Bykommend tot die herwinning van nikkel en kobalt uit laterite erts is hierdie proses uniek en daarop gemik om yster te herwin as ’n verkoopbare by-produk. Die vermindering van oplosbare yster(III) (Fe(III)) met swaeldioksied (SO2) is sentraal tot die ARFe konsep en verteenwoordig ’n komplekse, multifase stelsel wat gelyktydige gas-vloeistof massa-oordrag, termodinamiese spesiasie en chemiese reaksie behels. Die oplossingschemie van ysterstelsels word, oor die algemeen, swak verstaan en om hul gedrag akuraat te voorspel is ’n uitdaging, veral onder aggressiewe hidrometallurgiese kondisies. Die primêre doel van hierdie werk is die ontwikkeling van ’n ingenieursmodel wat die tempo en omvang van yster(III) vermindering met SO2 onder tipiese ARFe proses toestande beskryf. Termodinamiese oorwegings stel ’n streng raamwerk voor vir die interpretasie van chemiese reaksies, alhoewel daar egter min eksperimentele data openlik beskikbaar is vir die gepaardgaande oplossing spesies in suur yster(III) sulfaat stelsels. ’n Belangrike bydrae van hierdie werk, en van kritieke belang vir die ontwikkeling van die algehele model, is die direkte meting van spesiasie in yster(III) sulfaat oplossings. Raman en UV-vis spektroskopie is gebruik om direkte spesiasie metings te maak in die verskillende subsisteme van die Fe2(SO4)3-FeSO4-H2SO4-H2O stelsel wat voorheen nie in die oop literatuur beskikbaar was nie. Die FeSO+4 en Fe(SO4)– 2 spesies is ekplisiet geïdentifiseer, terwyl die metings ondersteun en gerasionaliseer is deur statiese kwantummeganiese berekeninge wat uiteindelik die kalibrasie van ’n robuuste, ioon-interaksie model tot gevolg hê wat ook die belangrike oplossingspesies duidelik beklemtoon tot en met 1.6 mol/kg Fe2(SO4)3, 0.8 mol/kg H2SO4 en tussen 25 – 90°C. Enkellading en kontinue yster(III) verminderingskinetika is gemeet en die gevolge van die aanvanklike Fe2(SO4)3 en H2SO4 konsentrasies, temperatuur en in-situ neutralisasie is gekwantifiseer. Die waargeneemde vertragingseffek van swaelsuur is die mees beduidende faktor wat die aanvanklike reaksietempo en die haalbare reaksie omvangsvermindering na ’n vaste residensietyd van 180 minute bepaal, wat wissel tussen ongeveer 20 en 80%. ’n Reaksiemeganisme word voorgestel wat beperk word deur die stadige ligand-totmetaal elektronoordrag in ontbinding van die Fe(III)SO+3 oplossing-spesies en wat verder deur spektroskopiese metings en kwantummeganiese berekenings ondersteun word. A kinetiese model, wat bestaan uit ’n stelsel van gedifferensieerde massa-balans vergelykings, is in die termodinamiese raamwerk geïnkorporeer. Hierdie reaksie-model laat die voorspelling van kinetiese profiele toe oor die volle omvang van die eksperimentele toestande en kan in meer uitgebreide simulasie modelle van die ARFe proces geinkorporeer word. Die spesifieke en oorspronklike bydraes van hierdie werk is • Die direkte meting van die spesiasie in die Fe2(SO4)3-H2SO4-H2O stelsel deur Raman en UV-vis spektroskopie • Die ontwikkeling van ’n modelraamwerk om spesiasie, aktiwiteitskoëffisiënte en oplosbaarheid in die gemengde Fe2(SO4)3-FeSO4-H2SO4-H2O stelsel te karakteriseer. • Die meting van yster(III) vermideringskinetieka deur SO2 in gekonsentreerde sulfate oplossings te gebruik as ’n funksie van die aanvanklike samestelling en temperatuur. • Die ontwikkeling van ’n oplossingsreaksie-model van yster(III) vermindering met SO2 wat die oplossing-spesiasie en reaksietempo met die tyd as ’n funksie van samestelling en temperatuur akkuraat voorspel. Laastens, die oorgrote kompleksiteit van industriële stelsels sal byna altyd lei tot ’n gebrek van spesifieke eksperimentele data wat nodig is vir die ontwikkeling van fenomenologiese modelle. Hierdie werk beklemtoon die belangrike rol wat ingenieursstudies speel in die generasie van data wat sodanig tot maksimum praktiese waarde vir industriële prosesontwikkeling en optimalisering lei.
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Hennig, Sandra Elisabeth. "Insights into the ATP-dependent reductive activation of the Corrinoid/Iron-Sulfur Protein of Carboxydothermus hydrogenoformans." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://dx.doi.org/10.18452/16984.

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Die Verknüpfung einer exergonischen mit einer endergonischen Reaktion zur Ermöglichung der letzteren ist eine in biologischen Systemen weit verbreitete Strategie. Energetisch benachteiligte Elektronenübertragungsreaktionen im Rahmen der reduktiven Aktivierung von Nitrogenasen, Radikal-abhängigen β,α-Dehydratasen, der zu diesen verwandten Benzoyl-CoA-Reduktasen und diversen Cobalamin-abhängigen Methyltransferasen sind gekoppelt an die Hydrolyse von ATP. Der Methylgruppentransfer des reduktiven Acetyl-CoA-Weges von Carboxydothermus hydrogenoformans erfordert den Co(I)-Zustand des Corrinoid/Eisen-Schwefel Proteins (CoFeSP). Um diese superreduzierte Form nach einer oxidativen Inaktivierung zu regenerieren ist ein „Reparaturmechanismus“ erforderlich. Ein offenes Leseraster (orf7), welches möglicherweise für eine reduktive Aktivase von Corrinoid Enzymen (RACE) kodiert, wurde in dem Gencluster der am reduktiven Acetyl-CoA-Weg beteiligten Proteine entdeckt. Im Rahmen dieser Arbeit wurde dieses potenzielle RACE Protein biochemisch und strukturell charakterisiert und die ATP-abhängige reduktive Aktivierung von CoFeSP untersucht. Auf Grundlage der in dieser Arbeit gewonnenen Ergebnisse wurde ein Mechanismus für die ATP-abhängige Aktivierung entworfen. Dieser gibt Einblicke wie die durch ATP-Hydrolyse bereitgestellte Energie einen energetisch ungünstigen Elektronentransfer ermöglichen kann. Hierzu kombiniert RACo das Ausgleichen von Bindungsenergien mit Modulationen am Elektronenakzeptor. Eine vergleichbare Strategie wurde bisher in keinem anderen ATP-abhängigen Elektronenübertragungssystem wie dem von Nitrogenasen, Radikal-abhängigen β,α-Dehydratasen oder Benzoyl-CoA-Reduktasen beobachtet und könnte ein für RACE Proteine allgemein gültige Eigenschaft darstellen.
The principle of coupling an exergonic to an endergonic reaction to enable the latter is a widespread strategy in biological systems. Unfavoured electron transfer reactions in the reductive activation of nitrogenases, radical-dependent β,α-dehydratases and the related benzoyl- CoA reductases, as well as different cobalamin-dependent methyltransferases are coupled to the hydrolysis of ATP. The reductive acetyl-CoA pathway of Carboxydothermus hydrogenoformans relies on the superreduced Co(I)-state of the corrinoid/iron-sulfur protein (CoFeSP) that requires a “repair mechanism” in case of incidental oxidation. An open reading frame (orf7) coding for a putative reductive activase of corrinoid enzymes (RACE) was discovered in the gene cluster of proteins involved in the reductive acetyl-CoA pathway. In this work, this putative RACE protein was biochemically and structurally characterised and the ATP-dependent reductive activation of CoFeSP was investigated. Based on the results of this study, a mechanism for the ATP-dependent reactivation of CoFeSP was deduced providing insights into how the energy provided by ATP could trigger this unfavourable electron transfer. The reductive activator of CoFeSP combines balance of binding energies and modulations of the electron acceptor to promote the uphill electron transfer to CoFeSP. A comparable strategy has not been observed in other ATP-dependent electron transfer systems like nitrogenases, radical-dependent β,α-dehydratases and benzoyl- CoA reductases and could be a universal feature of RACE proteins.
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Holanda, Roseanne. "A study of novel acidophilic Firmicutes and their potential applications in biohydrometallurgy." Thesis, Bangor University, 2018. https://research.bangor.ac.uk/portal/en/theses/a-study-of-novel-acidophilic-firmicutes-and-their-potential-applications-in-biohydrometallurgy(50564a50-13ed-4663-bec0-efa149957493).html.

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The application of biotechnologies in the mining sector has intensified over the last 30 years, driven by the increasing demand for metals associated with the rise in energy costs and the awareness for environmentally responsible mining practices. Acidophilic prokaryotes play an important role in biohydrometallurgy, facilitating the solubilisation and recovery of base metals from ores and waste materials. The potential of novel acidophiles of the phylum Firmicutes for applications in biohydrometallurgical processes is examined in this thesis. Eight strains of extremely acidophilic bacteria were studied and shown to belong to the proposed novel genus “Acidibacillus”. These had been isolated previously from several distinct global locations and were shown to be obligately heterotrophic bacteria with potential to carry out tasks critical to biomining such as regenerating ferric iron (by catalysing the dissimilatory oxidation of ferrous iron), generating sulfuric acid (by the oxidation of zero-valent sulfur and tetrathionate; two strains only), and removing potentially inhibitory dissolved organic carbon. These isolates also demonstrated the ability to catalyse the dissimilatory reduction of ferric iron in anaerobic conditions. Results obtained during this study provide the basis for future research to assess their potential roles in microbial consortia applied in the bio-processing of metal ores. A novel obligately anaerobic acidophilic Firmicute (strain I2511) isolated from sediment obtained from an abandoned copper mine, was characterised in terms of its phylogeny and physiology. This isolate formed a separated clade within the Firmicutes, and was considered to represent a novel candidate genus. It also displayed a unique set of physiological traits, distinct from currently validated species of acidophilic Firmicutes. The isolate was an obligate anaerobe that grew via zero-valent sulfur (ZVS) respiration, generating H2S over a wide pH range (1.8 - 5.0), and also catalysed the dissimilatory reduction of ferric iron. Strains of acidophilic sulfatereducing bacteria (aSRB), also Firmicutes, were shown to reduce ZVS at pH as low as 3. These aSRB, together with isolate I2511, populated a novel variant of a low pH sulfidogenic bioreactor. The “hybrid sulfidogenic bioreactor” (HSB) operated using both sulfate and ZVS as electron acceptors, and glycerol as electron donor. The bioreactor successfully remediated and recovered zinc from circum-neutral pH mine-impacted waters with distinct chemical composition collected from two abandoned lead/zinc mines in the U.K. The microbial consortium used in this system proved to be robust, in which the HSB generated H2S consistently under a wide pH range (2 – 7). Experiments demonstrated that H2S could also be generated abiotically in a non-inoculated low pH reactor, by the chemical reaction of ZVS and zero-valent iron to form iron sulfide, and the consequent acid dissolution of the latter. Operational costs and the advantages of biogenic and abiotic generation of H2S for recovery of transition metals from mine waters are discussed.
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Hennig, Sandra Elisabeth [Verfasser], Holger [Akademischer Betreuer] Dobbek, Erwin [Akademischer Betreuer] Schneider, and Peter [Akademischer Betreuer] Hildebrandt. "Insights into the ATP-dependent reductive activation of the Corrinoid/Iron-Sulfur Protein of Carboxydothermus hydrogenoformans / Sandra Elisabeth Hennig. Gutachter: Holger Dobbek ; Erwin Schneider ; Peter Hildebrandt." Berlin : Humboldt Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://d-nb.info/105259686X/34.

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7

Pham, Huynh Anh. "The dynamics of microbial ferric and sulfate reduction in acidic mine lake sediments and their impact on water quality." University of Western Australia. School of Environmental Systems Engineering, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0004.

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[Truncated abstract] Acidic mine lakes are formed as a result of the oxidation and dissolution of metal sulfide minerals and are primarily characterized by low pH values of 2 – 4. Many strategies for the bioremediation of acidic mine lakes depend on the alkalinity generation capabilities of microbial ferric and/or sulfate reducing bacteria. However nearly all mine lakes are oligotrophic, with very low concentrations of available organic carbon and nutrients; all required for healthy microbial growth. There is also an unusual class of mine lakes characterized by low concentrations of organic carbon and also very low concentrations of dissolved iron and sulfate. Our ability to promote microbial activity in these systems is especially challenging. This study focuses on one of these systems, Lake Kepwari, a coal mine lake in Western Australia. Numerical modeling of remediation strategies is an efficient way of testing scenarios prior to expensive in-field trials. However such modeling relies on good descriptions of microbial processes, including kinetic parameterizations of ferric and sulfate reduction. There has been little research to date on the study of kinetic parameterizations of the chemical and biological alkalinity generation in acidic mine lakes. The objectives of this thesis were to investigate the viability of microbial ferric and sulfate reduction in an ultraoligotrophic, acidic mine lake, to assess the impact of these microbial processes on water quality and to parameterize the Dual Monod kinetics of neutralization under dual limitation conditions. Molecular analyses including most probable number, DNA extraction, polymerase chain reaction, polymerase chain reaction – denaturing gradient gel electrophoresis were used to examine the microbial communities in the lake sediments. ... The Monod maximum specific microbial growth rates with respect to dissolved organic carbon and ferric, and as determined in batch experiments, were 0.07 ± 0.01 and 0.048 ± 0.02 day-1, respectively, and their corresponding Monod half saturation constants and were 14.37 and 5.6 mmol L-1. The Monod maximum consumption rates under ferric and OC limitation were also estimated. The Monod maximum specific microbial growth rates with respect to dissolved organic carbon and sulfate, , and were 0.05 ± 0.01, 0.08 ± 0.01 and 0.07 ± 0.02 day-1, respectively, and their corresponding Monod half saturation constants, and were 75.5, 131.8 and 10.2 mmol L-1. The Monod maximum consumption rates under sulfate and OC limitation were also estimated. The results of this study suggest that strategies for the remediation of ultraoligotrophic, acidic mine lakes may rely on microbial ferric and sulfate reduction, however additions of both organic carbon and sulfate/ferric are essential. These results can be immediately applied to mesocosm studies in outdoor enclosures and to the management of acidic mine lakes. Furthermore, this thesis has provided a new, valuable understanding on the Dual Monod kinetic parameterizations of neutralization for an ultraoligotrophic, acidic mine lake environment. These parameterizations are essential for the lake ecological models that will be used to investigate remediation scenarios for acidic mine lakes.
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Yuvaniyama, Pramvadee. "Biosynthesis of Iron-Sulfur Clusters." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/40388.

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It is not known whether biosynthesis of [Fe-S] clusters occurs through a spontaneous self-assembly process or an enzymatic process. However, in the Azotobacter vinelandii nitrogenase system, it has been proposed that NifS and NifU are involved in the mobilization of sulfur and iron necessary for nitrogenase-specific [Fe-S] cluster assembly. The NifS protein has been shown to have cysteine desulfurase activity and can be used to supply sulfur for the in vitro catalytic formation of [Fe-S] clusters. The activity of the NifU protein has not yet been established, but NifU could have functions complementary to NifS by mobilizing iron or serving as an intermediate site necessary for nitrogenase-specific [Fe-S] cluster assembly. A second iron-binding site within NifU was predicted to serve these functions because two identical [2Fe-2S] clusters that had previously been identified within the homodimeric NifU are tightly bound, and the NifU primary sequence is rich in cysteine residues. In this dissertation, I examined the possibility that NifU might mobilize iron or serve as an intermediate site for [Fe-S] cluster assembly, as well as the possibility that NifU could work in concert with NifS. Primary sequence comparisons, amino acid substitution experiments, and biophysical characterization of recombinantly-produced NifU fragments were used to show that NifU has a modular structure. One module is contained in approximately the C-terminal half of NifU and provides the binding site for the [2Fe-2S] cluster previously identified (the permanent [2Fe-2S] cluster). Cysteine residues Cys¹³⁷, Cys¹³⁹, Cys¹⁷⁵, and Cys¹⁷⁵ serve as ligands to the [2Fe-2S] cluster. Another module (referred to as NifU-1) is contained in approximately the N-terminal third of NifU and provides a second iron-binding site (rubredoxin-like Fe(III)-binding site). Cysteine residues Cys35, Cys⁶², Cys¹⁰⁶>, and a putative non-cysteine ligand of unknown origin provide coordination to the iron at this site. The significance of these iron-binding sites was also accessed by showing that cysteine residues involved in providing the rubredoxin-like Fe(III)-binding site and those that provide the [2Fe-2S] cluster binding site are all required for the full physiological function of NifU. The two other cysteine residues contained within NifU, Cys²⁷² and Cys²⁷⁵, are neither necessary for binding iron at either site nor are they required for the full physiological function of NifU. These results provide the basis for a model where iron bound at the rubredoxin-like sites within NifU-1 (one iron per monomer) is proposed to be destined for [Fe-S] cluster formation. It was possible to find in vitro evidence supporting this idea. First, it was demonstrated that NifU and NifS are able to form a transient complex. Second, in the presence of NifS as well as L-cysteine and a reducing agent, the Fe(III) contained at the rubredoxin-like sites within the NifU-1 or NifU homodimer can rearrange to form a transient [2Fe-2S] cluster between the two subunits. Finally, a mutant form of NifU-1 was isolated that appears to be trapped in the [2Fe-2S] cluster-containing form, and this [2Fe-2S] cluster (the transient [2Fe-2S] cluster) can be released from the polypeptide matrix upon reduction with dithionite. Previous work has shown that the permanent [2Fe-2S] clusters of as-isolated NifU are in the oxidized form but can be reduced chemically. The transient [2Fe-2S] cluster formed between rubredoxin-like sites, in contrast, is reductively labile. If the transient cluster serves as an intermediate [Fe-S] cluster to be destined for [Fe-S] cluster assembly, I propose that the permanent [2Fe-2S] clusters could have redox roles participating in either one or all of the following events. The permanent [2Fe-2S] clusters could have a redox function in the acquisition of iron for initial binding at the mononuclear sites. They could also provide reducing equivalents for releasing the transient [2Fe-2S] cluster. In addition, upon releasing the transient [2Fe-2S] cluster, the permanent [2Fe-2S] clusters could provide the appropriate oxidation state of the irons to be destined to nitrogenase metallocluster core formation. Finally, because proteins homologous to NifU and NifS are widely distributed in nature, it is suggested that the mechanism for NifU and NifS in the formation of nitrogenase-specific [Fe-S] clusters could represent a general mechanism for [Fe-S] cluster synthesis in other systems.
Ph. D.
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9

Wu, Shu-Pao. "Iron-sulfur cluster biosynthesis. Iron-sulfur cluster transfer from Holo ISU and ISA to Apo Fd." The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1078866123.

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Wu, Shu-Pao. "Iron-sulfur cluster biosynthesis. Iron-sulfur cluster transfer from holo ISU and ISA to apo ferredoxin." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1078866123.

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Thesis (Ph. D.)--Ohio State University, 2004.
Title from first page of PDF file. Document formatted into pages; contains xx, 161 p.; also includes graphics Includes bibliographical references (p. 153-161). Available online via OhioLINK's ETD Center
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Books on the topic "Sulfur and iron reduction"

1

Cammack, Richard. Iron-Sulfur Proteins. Burlington: Elsevier, 1999.

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Rouault, Tracey, ed. Iron-Sulfur Clusters in Chemistry and Biology. Berlin, Boston: DE GRUYTER, 2014. http://dx.doi.org/10.1515/9783110308426.

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Iron-sulfur clusters in chemistry and biology. Berlin: Walter de Gruyter GmbH & Co., 2014.

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Ragin, Margaret M. Recovery of sulfur from phosphogypsum: Conversion of calcium sulfate to calcium sulfide. Washington, D.C. (2401 E St., N.W., MS #9800, Washington 20241): U.S. Dept. of the Interior, Bureau of Mines, 1990.

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Bejarano, Cesar. Carbothermal reduction of sulfur dioxide using oil-sands fluid coke. Ottawa: National Library of Canada, 2000.

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Ōae, Shigeru. Organic sulfur chemistry: Structure and mechanism. Edited by Doi Joyce Takahashi. Boca Raton, Fla: CRC Press, 1991.

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Stucki, J. W. Oxidation-reduction mechanisms in iron-bearing phyllosilicates. Athens, GA: U.S. Environmental Protection Agency, Environmental Research Laboratory, 1993.

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Knocke, William R. Chlorite ion reduction by ferrous iron addition. Denver, CO: AWWA Research Foundation and American Water Works Association, 1993.

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Stucki, J. W. Oxidation-reduction mechanisms in iron-bearing phyllosilicates. Athens, GA: U.S. Environmental Protection Agency, Environmental Research Laboratory, 1993.

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Stucki, J. W. Oxidation-reduction mechanisms in iron-bearing phyllosilicates. Athens, GA: U.S. Environmental Protection Agency, Environmental Research Laboratory, 1993.

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Book chapters on the topic "Sulfur and iron reduction"

1

Speelman, Amy L., and Patrick L. Holland. "Sulfur-Supported Iron Complexes for Understanding N2 Reduction." In Nitrogen Fixation, 197–213. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/3418_2016_4.

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Kupka, Daniel, Mark Dopson, and Olli H. Tuovinen. "Sulfur Oxidation and Coupled Iron Reduction at Low Temperatures." In Advanced Materials Research, 584. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-452-9.584.

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Gooch, Jan W. "Sulfur Reduction." In Encyclopedic Dictionary of Polymers, 926. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_14892.

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Cohen, G. N. "Iron–Sulfur Proteins." In Microbial Biochemistry, 127–32. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-90-481-9437-7_11.

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Cohen, G. N. "Iron-Sulfur Proteins." In Microbial Biochemistry, 139–45. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-94-017-8908-0_11.

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Jarrett, Joseph T. "Iron–Sulfur Clusters." In Encyclopedia of Biophysics, 1153–56. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-16712-6_44.

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Cohen, Georges N. "Iron-Sulfur Proteins." In Microbial Biochemistry, 195–202. Dordrecht: Springer Netherlands, 2016. http://dx.doi.org/10.1007/978-94-017-7579-3_11.

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Tretyachenko, Ludmyla. "Iron – Magnesium – Sulfur." In Iron Systems, Part 4, 170–79. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-78644-3_14.

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Tomashik, Vasyl, and Hans-Leo Lukas. "Iron – Manganese – Sulfur." In Iron Systems, Part 4, 284–318. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-78644-3_20.

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Fortney, Nathaniel W., Stephanie A. Napieralski, and Eric E. Roden. "Iron Reduction." In Encyclopedia of Astrobiology, 1–4. Berlin, Heidelberg: Springer Berlin Heidelberg, 2019. http://dx.doi.org/10.1007/978-3-642-27833-4_5402-1.

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Conference papers on the topic "Sulfur and iron reduction"

1

Tortorelli, Peter F., Claudette G. McKamey, Edgar Lara-Curzio, and Roddie R. Judkins. "Iron-Aluminide Filters for Hot-Gas Cleanup." In ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-268.

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Iron aluminides have shown good to excellent high-temperature corrosion resistance in sulfur-bearing environments and thus have potential for use as the material of construction for metallic filters used to clean fossil-fuel-derived gases prior to their introduction into gas turbine systems. Consequently, a background for consideration of such alloys for filter applications is given in terms of a brief summary of the physical metallurgy and relevant high-temperature corrosion behavior of iron aluminides. In addition, preliminary characterization results on iron-aluminide filter elements exposed in test beds that simulate environments associated with advanced coal-fired energy production are presented. Although good corrosion resistance was found, there were minor to moderate strength reductions that did not necessarily scale with time. Little degradation in ductility was observed.
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Kolmachikhina, E. B., T. N. Lugovitskaya, M. A. Tretyak, and K. D. Naumov. "Kinetic investigation of surfactants’ influence on pressure leaching of zinc sulfide concentrates." In VIII Information school of a young scientist. Central Scientific Library of the Urals Branch of the Russian Academy of Sciences, 2020. http://dx.doi.org/10.32460/ishmu-2020-8-0004.

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Pressure leaching is one of the most high-demanded and promising hydrometallurgical technology, which allows one to obtain high efficiency. Taking into account the shutdown of zinc plant in Vladikavkaz («Electrozinc, Lls.») searching the modern methods of zinc production is of current interest. In this work, the issue was observed on influence of temperature and sodium lignosulfonate (SL) onto the zinc and iron sulfides behavior during pressure leaching of zinc sulfide concentrate from the Uchalinsk deposit. Temperature increasing from 130 to 150oC led to decreasing of zinc extraction and sulfur-sulfide pellets formation; that indicated increasing the zinc sulfide wettability by the molten sulfur due to reduction of viscosity and surface tension of molten sulfur. Increasing the LSN dosage promoted running up of the absolute value of the zinc extraction. The highest growth of the zinc extraction (17.39 %) was obtained at 0.2 g/dm3 LSN. Further increasing of the LSN concentration on 0.2 g/dm3 (up to 0.4, 0.6, 0.8 g/dm3) led to double decrease of their effectiveness in reference to previous LSN concentration.
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Semkin, M. A., N. B. Urusova, and A. N. Pirogov. "Features of structure state and magnetic properties of mono- and polycrystalline LiNiPO4 and LiNi0.9Co0.1PO4." In VIII Information school of a young scientist. Central Scientific Library of the Urals Branch of the Russian Academy of Sciences, 2020. http://dx.doi.org/10.32460/ishmu-2020-8-0005.

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Pressure leaching is one of the most high-demanded and promising hydrometallurgical technology, which allows one to obtain high efficiency. Taking into account the shutdown of zinc plant in Vladikavkaz («Electrozinc, Lls.») searching the modern methods of zinc production is of current interest. In this work, the issue was observed on influence of temperature and sodium lignosulfonate (SL) onto the zinc and iron sulfides behavior during pressure leaching of zinc sulfide concentrate from the Uchalinsk deposit. Temperature increasing from 130 to 150o C led to decreasing of zinc extraction and sulfur-sulfide pellets formation; that indicated increasing the zinc sulfide wettability by the molten sulfur due to reduction of viscosity and surface tension of molten sulfur. Increasing the LSN dosage promoted running up of the absolute value of the zinc extraction. The highest growth of the zinc extraction (17.39 %) was obtained at 0.2 g/dm3 LSN. Further increasing of the LSN concentration on 0.2 g/dm3 (up to 0.4, 0.6, 0.8 g/dm3 ) led to double decrease of their effectiveness in reference to previous LSN concentration.
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Zhang, Chun-Lin, De-Chang Liu, and Han-Ping Chen. "The Effects of Heterogeneous Reactions on the Reduction of NO in Petroleum-Coke-Fired Fluidized Beds." In 18th International Conference on Fluidized Bed Combustion. ASMEDC, 2005. http://dx.doi.org/10.1115/fbc2005-78085.

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Because of high heating value, low volatile, high nitrogen content and high sulfur content, some kinds of petroleum coke are only suitable for use as fuel, especially combusted in fluidized beds. Based on experiments in a 1t/h fluidized bed, we found that lots of NO and N2O were emitted, and they reached to 780ppm and 150ppm respectively. By analyzing the contributions of char-N and volatile-N to the formation of NO and N2O, we also found it was more important to control the combustion of char to reduce the emission of NO and N2O. This paper tried to find a denitrification agent that could work as desulfuration agent in fluidized beds. We chose Fe as the denitrification agent. The influence of iron on the reduction of NO was studied on. The effects of petroleum-coke char, CO and limestone on the reaction of iron and NO were investigated in a bench scale fluidized bed. Quantitative Fe and petroleum coke char were added into a quartz sand bed respectively, the conversions of NO between these conditions were compared with. The results showed that the ability of Fe to reduce NO was much stronger than the char, and the conversion of NO almost reached to 100%. After minutes that depended on the amount of Fe, Fe was oxidized to oxide of Fe, and the conversion of NO decreased. Petroleum coke char could deoxidize the oxide of Fe. Fe that mixed with petroleum coke char could apparently increase the reaction time of Fe and NO. CO was also a reductive agent of the oxide of Fe, but the effect was not strong as char. Limestone little increased the conversion of NO. From the experiments, we suggested that iron or its oxides would be a possible denitrification agent to reduce NO in fluidized beds in situ.
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Uozato, S., K. Nakata, and M. Ushio. "Development of Ferrous Powder Thermal Spray Coatings on Cylnder Bore in Diesel Engine." In ITSC2004, edited by Basil R. Marple and Christian Moreau. ASM International, 2004. http://dx.doi.org/10.31399/asm.cp.itsc2004p0290.

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Abstract Aluminum alloy has been gradually utilized in cylinder block instead of ferrous casting material for weight reduction in automobile industry these days. In order to acquire more weight reduction, a new liner-less technology - without cast iron liner used - is putting into practice in the fields of aluminum cylinder block and the target is for diesel engine. However, diesel fuel's impurity "sulfur" element and corrosive attack risk, such as sulfuric acid generated to the surface of liner is higher than gasoline fuel. Because of such disadvantage, wear and corrosion resistances applied to the inner cylinder-bore are required in order to achieve this liner-less aluminum cylinder block. This research is intended to accomplish both wear and corrosion performances using plasma thermal spray technology and to verify the feasibility of application to actual engine bore. A newly-developed ferrous powder (Fe-C-Ni-Cr-Cu-V-B alloy) revealed extremely excellent corrosion and wear resistances, compared with currently used bulk casting materials such as Fe-C-Si-B alloy and Fe-C-Si-Mo-B alloy for cylinder liner. For the last time, the new ferrous alloy powder was applied to actual engine bore by using Rota-Plasma spray coating. The experimental results with engine bore presented potential equivalent to current engine bore.
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6

Wada, Kentaro, Junichiro Yamabe, and Hisao Matsunaga. "Visualization of Trapped Hydrogen Along Grain Boundaries and its Roles on Hydrogen-Induced Intergranular Fracture in Slow Strain Rate Tensile Testing of Pure Nickel." In ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21021.

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Abstract It has been reported that hydrogen accumulation along grain boundaries (GBs) is an important process in the hydrogen embrittlement (HE) in pure Ni. However, there are no quantitative studies that elucidate the behavior of hydrogen accumulation and its effect on HE. Consequently, the segregating behavior of hydrogen along GBs and its role in intergranular (IG) fracture in pure Ni were examined in the present research, via a combination of thermal desorption analysis, secondary iron mass spectrometry, Auger electron spectroscopy and slow strain rate tensile testing. It was successfully demonstrated that the hydrogen trapped at GBs and the sulfur segregated along GBs contributed to the hydrogen-trapping. In addition, the contribution of trapped hydrogen on the hydrogen-induced ductility loss was quantitatively investigated. The results revealed a decreased reduction in area (RA) with a concomitant increase in trap-site occupancy, implying that the trapped hydrogen controlled the hydrogen-induced IG fracture and ductility loss in pure Ni.
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7

Gilman, Thane. "Shore Power Supply (Cold Ironing) for Ships: Reducing Ship Engine Emissions." In ASME/USCG 2010 2nd Workshop on Marine Technology and Standards. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/mts2010-0206.

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Cold Iron: Receipt of shore power, along with other utilities such as potable water and steam, is part of the process of placing the engineering plant in a status known as “cold iron.” The term originates from the steamship era, when ship boilers and engines would go relatively cold after being secured. To bring a steam plant back online, supplying its own power after a “cold iron” period, would involve a substantial light-off, warm-up, and transition period compared to modern, fully automated plants. Onshore power supply (OPS, sometimes referred to as “cold ironing”) is a system of procedures and equipment that provides ships with a source of electrical power as an alternative to the ship’s service electrical power system. The primary benefit is that, since the ship no longer has main or auxiliary engines operating, the engine emissions are virtually eliminated in the port area. Many ports around the world are located near large populations, and engine emissions from ships unfortunately contribute to unwanted levels of nitrogen oxides, sulphur oxides, particulate matter, and even the “greenhouse gas” carbon dioxide. Onshore power supply achieves a better total emissions reduction result than ship-installed emissions equipment, because the engines are off-line. On the other hand, there are difficulties associated with high voltage, varying frequencies, safety and infrastructure costs that must be addressed in order to justify an onshore power supply installation. Paper published with permission.
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Medzhidzade, V. A., A. Sh Aliev, and D. B. Tagiev. "ELECTROCHEMICAL DEPOSITION OF IRON WITH SULFUR." In RENEWABLE ENERGY: CHALLENGES AND PROSPECTS. ALEF, 2020. http://dx.doi.org/10.33580/2313-5743-2020-8-1-514-516.

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Снятием потенциодинамических циклических поляризационных кривых на Pt подложках изучена кинетика, механизм процесса (в широком диапазоне потенциалов) и определена область потенциалов совместного электроосаждения Fe с S из неводных электролитов. Структура, стехиометрия и морфология тонких пленок Fe-S, осажденных потенциостатическим и гальваностатическим методами, определены с помощью СЭМ и рентгенофазового анализа.
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Kamyshny, Alexey, Valeria Boyko, Khoren Avetisyan, Alyssa Findlay, Qingjun Guo, Xi Yang, and Andre Pellerin. "Sulfur, manganese and iron transformations in low-sulfate iron-rich Lake Sihailongwan." In Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.10481.

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McGuinness, Kenneth. "Did iron-sulfur containing minerals and proteins coevolve?" In Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.8001.

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Reports on the topic "Sulfur and iron reduction"

1

Liu, Wei, M. Flytzani-Stephanopoulos, and A. F. Sarofim. Selective catalytic reduction of sulfur dioxide to elemental sulfur. Office of Scientific and Technical Information (OSTI), January 1992. http://dx.doi.org/10.2172/6666173.

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Liu, W., M. Flytzani-Stephanopoulos, and A. F. Sarofim. Selective catalytic reduction of sulfur dioxide to elemental sulfur. Final report. Office of Scientific and Technical Information (OSTI), June 1995. http://dx.doi.org/10.2172/155283.

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Hepworth, M. T. Molten iron oxysulfide as a superior sulfur sorbent. Office of Scientific and Technical Information (OSTI), January 1991. http://dx.doi.org/10.2172/7113017.

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Hepworth, M. T. Molten iron oxysulfide as a superior sulfur sorbent. Office of Scientific and Technical Information (OSTI), January 1991. http://dx.doi.org/10.2172/7296816.

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Hepworth, M. T. Molten iron oxysulfide as a superior sulfur sorbent. Office of Scientific and Technical Information (OSTI), January 1990. http://dx.doi.org/10.2172/7296824.

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Hepworth, M. T. Molten iron oxysulfide as a superior sulfur sorbent. Office of Scientific and Technical Information (OSTI), January 1990. http://dx.doi.org/10.2172/7234004.

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Hepworth, M. T. Molten iron oxysulfide as a superior sulfur sorbent. Office of Scientific and Technical Information (OSTI), January 1991. http://dx.doi.org/10.2172/7042821.

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H.Y. Sohn. Suspension Hydrogen Reduction of Iron Oxide Concentrates. Office of Scientific and Technical Information (OSTI), March 2008. http://dx.doi.org/10.2172/929441.

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9

Ron Rohrbach, Gary Zulauf, and Tim Gavin. ULTRA-LOW SULFUR REDUCTION EMISSION CONTROL DEVICE/DEVELOPMENT OF AN ON-BOARD FUEL SULFUR TRAP. Office of Scientific and Technical Information (OSTI), April 2003. http://dx.doi.org/10.2172/824877.

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Rohrbach, Ron, and Ann Barron. Ultra-low Sulfur Reduction Emission Control Device/Development of an On-board Fuel Sulfur Trap. Office of Scientific and Technical Information (OSTI), July 2008. http://dx.doi.org/10.2172/947010.

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