Abstract. The oxidation of a pure pyrite by Thiobacillus ferrooxidans is not really a constant phenomenon; it must be considered to be more like a succession of different steps which need characterization. Electrochemical studies using a combination of a platinum electrode and a specific pyrite electrode (packed-ground-pyrite electrode) revealed four steps in the bioleaching process.
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Jan 09, 2001· Re: Pyrite oxidation. Date: Tue, 9 Jan 2001 10:12:11 -0800. I haven't worked in AMD environments in a while, so I don't have any current pyrite oxidation examples. The manual does have a Fe+2 oxidation example and there is a rate expression for pyrite oxidation in phreeqc.dat. Sorry I'm not much help here. You may want to contact Tony Appelo ...
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Jun 13, 2013· Pyrite (FeS 2) commonly occurs in the Earth's surface environments 1.Great efforts have been made for the past decades to understand the mechanisms and kinetics of pyrite oxidation …
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Waters draining from abandoned coal or metals mines are often regarded as an environmental threat. Historical examples from the lead and coal mining industries of central and northeastern England illustrate that mine waters can also be regarded as an important resource in terms of 1) baseflow for effluent dilution; 2) drinking or industrial waters; 3) flocculating agents for sewage or water ...
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Jul 12, 2020· The field data were compared to predictions from simulations of pyrite oxidation using a 1-D numerical model. The simulations' estimates of the amount of Fe and S released over a seven year period (52 kg and 178 kg, respectively) were in reasonably good agreement with those obtained by analysing the tailings (34 kg and 155 kg, respectively).
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pyrite oxidation and its control amd molecular oxidation mechanisms microbial role k is available in our book collection an online access to it is set as public so you can download it instantly. Our digital library saves in multiple locations, allowing you to get the most less latency time to …
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Jun 25, 2021· 10%· The U(VI) immobilization efficiency and mechanism of natural pyrite were investigated under both acidic and neutral oxidization conditions. The results show that, the final U(VI) removal rate was only 20% under acidic condition; however, a small amount of pyrite oxidation could enhance the immobilization of U(VI) under neutral oxidizing conditions, with the removal rate …
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Feb 09, 2021· The oxidation of framboidal pyrite is considered to be fast due to its high specific surface area (SSA) ( Pugh et al., 1984. Pugh, C.E., Hossner, L.R., Dixon, J.B. (1984) Oxidation rate of iron sulfides as affected by surface area, morphology, oxygen concentration and autotrophic bacteria. Soil Science 137, 309–314.
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Nov 29, 2003· The effect of a diacetylene-containing phospholipid on the oxidation of pyrite, FeS2, was investigated. Earlier work reported by our research group showed that the adsorption of l,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine on pyrite suppressed the extent of its oxidation by about 75% over a specific time period. Results presented here show that the pre-exposure to UV radiation of ...
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Nov 01, 2020· Pyrite oxidation, which can lead to acid mine drainage, is a concern for miners all across the globe. However, little is known about the processes that cause this phenomenon.
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The lower Paleozoic units that comprise this aquifer system have been observed to host varying abundances of metal-sulfide minerals, such as pyrite, across Eastern, Western, and South-Central Wisconsin, USA. The oxidation of pyrite present within this aquifer system can generate groundwater contamination, releasing acidity and dissolved metals.
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Surface oxidation of pyrite as a function of pH, ... The variation of hydrogen peroxide in rainwater over the South and Central Atlantic Ocean, (1980). X-ray photoelectron spectra of 3d transition metal pyrites, (1994). X-ray photoelectron spectroscopic study of a pristine pyrite …
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It is well accepted that thiosulfate is central in much of the thinking concerning pyrite oxidation pathways. Luther (1987) provided the theoretical framework supporting the role of thiosulfate as an initial soluble intermediate in the pathway of pyrite oxidation. Rimstidt and Vaughan (2003) also postulated a separate pathway for formation
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Jul 15, 2018· This regional impact has global consequences for the cycling of sulfur. While mountaintop mining operations in Central Appalachia cover less than 0.006% of the land area of Earth, they contribute a globally significant amount of sulfate to surface water through pyrite oxidation.
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Pyrite (FeS 2) is an ubiquitous constituent of carbonate and clastic reservoir rocks.Pyrite is particularly abundant in shales, and may be an unrecognized cause of well bore or casing failures in shaly intervals. Pyrite is only stable at very low oxidation states, partly depending on the pH and temperature, and consequently is very susceptible to oxidation during injection of fluids of ...
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Feb 01, 1990· Oxide accumulation on the pyrite surfaces under neutral pH conditions results in a significant reduction in oxidation rates over time. This behaviour has important implications for the reduction of the rate of release of oxidation products, including hydrogen ions, to environments where sulphide mineral wastes are exposed to the atmosphere.
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Pyrite oxidation is sufficiently exothermic that underground coal mines in high-sulfur coal seams have occasionally had serious problems with spontaneous combustion. The solution is the use of buffer blasting and the use of various sealing or cladding agents …
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6.4 Pyrite Surface Functional Groups 148 6.4.1 Pyrite oxidation effects by iron-carbonate complexes. 156 6.5 Kinetics of Pyrite Oxidation 159 6.5.1 Empirical pyrite oxidation rate laws 161 6.5.2 Application of pyrite oxidation kinetics 164 6.5.3 Shrinking core model kinetics 168 6.6 Effect of Anions on Oxidation of Fe2+ 170 CHAPTER 7
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problems were related to pyrite oxidation and sulfate formation, and some were related to expanding clays in the shale. Geology and Hydrology Estill County is located along the eastern flank of the Cincinnati Arch and in the west-central part of the Rome Trough in eastern Kentucky. The county seat,
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Jan 08, 2001· Pyrite oxidation. Date: Mon, 8 Jan 2001 16:28:27 +0200. Dear Dr Parkhurst, PHREEQC2 offers exciting opportunity to conduct kinetic modelling. Working with tailings on gold mines and discard dumps on coal mines one of the problems encountered is pyrite oxidation. I'd like to gather some example files which deal with kinetic pyrite oxidation (in ...
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The Historical Use Of Mine-Drainage And Pyrite-Oxidation Waters In Central And Eastern England, United Kingdom. Download. The Historical Use Of Mine-Drainage And Pyrite-Oxidation Waters In Central And Eastern England, United Kingdom. Paul Younger. David Banks. Steve Dumpleton. Paul Younger. David Banks.
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Pyrite oxidation mechanism in aqueous medium. Jiling Feng. College of Chemistry and Chemical Engineering, Central South University, Changsha, China. Hunan Provincial Key Laboratory of Efficient and Clean Utilization of Manganese Resources, Changsha, China. Search for more papers by this author.
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Pyrite oxidation is a major concern related to waste rock excavated during mining operations. Pyrite and other iron-bearing sulfide minerals oxidize in the presence of oxygen and water and can produce acid, as well as iron oxyhydroxides and sulfate (reaction 1). ... the samples appeared to provide a central tendency for these data. ...
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Nov 15, 2018· Oxidation of aqueous reduced S compounds (e.g., H 2 S) during early diagenesis cannot be ruled out, although the low Fe Py /Fe HR ratios, as reflected by the large proportion of Fe(III) oxyhydroxides relative to pyrite in the Fe HR fraction (Section 3.4, Fig. 7), and environmental chemical proxies indicating a prolonged anoxic-dysoxic ...
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The oxidation of pyrite in aqueous systems is a complex biogeochemical process involving several redox reactions and microbial catalysis. This paper reviews the kinetic data on pyrite oxidation, compares available data on the inorganic vs. microbial oxidative mechanisms and describes the occurrence of mineral products resulting from pyrite oxidation.
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The pyrite-goethite transformation might be an important biogeochemical pathway for pyrite weathering. Citation. Xin Gu*, Peter Heaney, and Susan L. Brantley (2018): Pyrite oxidation during shale weathering: from catchment – to nanometer – scale. Abstract 12e:306 presented at 2018 Goldschmidt Meeting, Boston, MA 12-17 August .
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Jan 31, 2019· The mineral pyrite is considered the most common form of the sulfide minerals. Its oxidation is a very important process in nature, which involves in the redox recycling of iron. However, because of the growing need for the industrial production, sulfide oxidation produces more and more acid mine (or rock) drainage.
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Nov 20, 2012· The Historical Use Of Mine-Drainage And Pyrite-Oxidation Waters In Central And Eastern England, United Kingdom. David Banks 1, Paul L. Younger 2 & Steve Dumpleton 3 Hydrogeology Journal volume 4, pages 55–68 (1996)Cite this article
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Pyrite Oxidation and its Control is the single available text on the market that presents the latest findings on pyrite oxidation and acid mine drainage (AMD). This new information is an indispensable reference for generating new concepts and technologies for controlling pyrite...
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Apr 26, 2010· Background. Pyrite (FeS 2), the most common metal sulfide mineral associated with coal and metal mine waste, has been shown to generate hydrogen peroxide (H 2 O 2) [1,2] and hydroxyl radicals (• OH) [3,4] when placed in water.In the presence of dissolved molecular oxygen, ferrous iron associated with pyrite can form superoxide anion (O 2 •) - (eq. 1), which reacts with ferrous iron to …
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Pyrite Oxidation and its Control is the single available text on the market that presents the latest findings on pyrite oxidation and acid mine drainage (AMD). This new information is an indispensable reference for generating new concepts and technologies for controlling pyrite oxidation.
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Pyrite Oxidation and its Control is the single available text on the market that presents the latest findings on pyrite oxidation and acid mine drainage (AMD). This new information is an indispensable reference for generating new concepts and technologies for controlling pyrite oxidation.
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Sep 08, 2001· The oxidation of pyrite (FeS2) contained in unsaturated aquifer sediment was studied by sediment incubation in gas impermeable polymer laminate bags. Reaction progress was followed over a period of nearly 2 months by monitoring the gas composition within the laminate bag. The gas phase in the incubation bags became depleted in O2 and enriched in CO2 and N2 and was interpreted as due to pyrite ...
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Pyrite oxidation was carried out under conditions of constant pH, pt^ and temperature in a thermostadted glass reaction vessel, with a magnetic stirrer suspended from the cap and with two side ports. The two side ports were equipped with a gas-inlet tube plus inlet tube for NaOH titrant and
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Pyrite surface passivating layers, incorporating silicate from the natural dissolution of reactive silicate minerals in real waste rocks, can be preserved in a continuous, coherent, and stable form at pH ≥ 6, and have been found to reduce the pyrite oxidation rate by 50–95% [3,4].However, in some cases the establishment of these stable surface layers requires initial short-term treatment ...
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proved that the oxidation of pyrite in air with a low heating rate up to a temperature of 753 K in a furnace took place in a direct oxidation way to form iron oxides. The technique of Möss spectroscopy used in the work of Prasad et al. [14] showed that pyrrhotite was detected after roasting pyrite in air at a temperature of 883 K.
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This report presents an assessment of pyrite weathering on the chemistry of water in the abandoned Podwiśniówka quarry of the holy cross mountains (south-central Poland). This quarry did not operate for ore minerals, but for quartzites. The area of the pit pond enlarges each year generally as a result of an influx of spring snowmelt or heavy rainfall. The water examined reveals a very low ph ...
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Feb 19, 2018· The oxidation of pyrite also plays key role in supergene alteration of ore deposits, the formation of acid sulfate soils, etc. Pyrite oxidation is generally recognized as a complicated process which includes several oxidation/reduction reactions, complexation and hydrolysis reactions, and solid/solution equilibria.
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