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Showing 1 to 19 of 19 for “"pyrite oxidation"”.
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Geotechnical Problems with Pyritic Rock and Soil
Oxidation of pyrite can significantly affect properties and the behavior of soil and rock in civil construction. Problems with pyritic rock and soil extend globally and across many disciplines. Consequences of pyrite oxidation include heave, concrete degradation, steel corrosion, environmental …
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The batch and continuous bacterial leaching kinetics of a refractory gold-bearing pyrite concentrate
The recent focus on bacterial leaching as a preoxidation step in the treatment of refractory gold bearing sulphide ores and concentrates, has created the need for kinetic models to adequately describe bacterial leaching reactor performance. This work is a kinetic study of the bacterial leaching of …
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Effect of Coatings on Mineral Reaction Rates in Acid Mine Drainage
… iron oxyhydroxide coatings form on oxidizing pyrite and the potential strategies to prevent "runaway" AMD by reducing the rate of acid production to the point that the acid can be neutralized by the surrounding rocks. In both studies, experiments were conducted to measure reaction rates for …
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The engineering geology and stability of the rapidly alternating limestone and mudrock sea cliffs of glamorgan
… weatherability was greatest in such mudrocks. Pyrite oxidation was shown not only to enhance carbonate leaching, but to degrade the clay minerals and induce rehydration of the double layer. <br/>Uniaxial compressive strengths of representative mudrocks were determined for a range of moisture …
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Early evolution of environments and metabolism: insights from nitrogen, selenium and sulfur isotopes
… and late Archean enhancement of biological pyrite oxidation on land, leading to increasing fluxes of sulfate and other nutrients to the ocean. In the third part (Chapters 4-7), I further test this hypothesis through analyses of selenium isotopes and abundances. After establishing a new …
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Geochemical Reactions in Unsaturated Mine Wastes
… the pore spaces in the waste piles. The rate of pyrite oxidation in moist air was determined by measuring over time the change in pressure between a sealed chamber containing pyrite plus oxygen and a control. The experiments carried out at 25?C, 96.8% fixed relative humidity, and oxygen partial …
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The influence of fly ash additions on acid mine drainage production from coarse coal refuse
… unamended controls. Overall, the inhibition of pyrite oxidation by high ash blends was attributed to alkalinity effects, chemisorption, decreased hydraulic conductivity, and decreased oxygen diffusion to pyritic surfaces. Ash alkalinity and refuse potential acidity must be balanced for …
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Influence of fly ash and other treatments on acid mine drainage from coal refuse
… for extended periods of time and stabilized pyrite while neutralizing any acidity. The rock-P treatment appears to have bound free Fe and other elements released from pyrite oxidation but did not prevent acidification. Long term analysis may prove fly ash to be a viable alternative to …
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Arsenic Release from Chlorine Promoted Oxidation of Pyrite in the St. Peter Sandstone Aquifer, Eastern Wisconsin
… by increasing the rate of sulfide mineral oxidation. Current guidance from the Wisconsin Department of Natural Resources recommends a "low-dose" treatment of 20% of the chlorine strength and 10% of the of the contact time of chlorine treatments used in non-arsenic impacted wells for well …
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Experimental and Theoretical Studies of Kinetics and Quality Parameters to Determine Spontaneous Combustion Propensity of U.S. Coals
… that cause the self-heating of coal. Their oxidation at lower temperatures than that of fixed carbon to initiate coal's self-heating should be quantified.;In order for better understanding spontaneous combustion behavior, the following research has been done in this dissertation:;• …
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The mobility of metals in acid mine drainage from abandoned coal mines
… waters appeared to be controlled by pyrite oxidation and the solubility of the basic iron sulphate mineral jarosite. In contrast Al mobility appeared to be influenced by different mechanisms. Acidity of the Blesbokspruit waters correlated well (r = 0.942) with Al concentrations in the …
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Polycyclic Aromatic Hydrocarbons and Redox Parameters in a Creosote-Contaminated Aquifer
… that they are being used in the biological oxidation of PAHs. Although laboratory studies document the oxidation of PAHs under sulfate-reducing conditions, high aqueous sulfate values were recorded throughout the site, regardless of the level of contamination. Several possible mechanisms are …
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The geochemical evolution of saline groundwater within a fresh water aquifer south of Oakes, North Dakota
… Gypsum (CaSO4 .2H2O) yields Ca2+ and SO42- ions. Pyrite oxidation yields Fe and SO42- ions. The tills and surficial clays contain montmorillonite, presumably sodium montmorillonite, which in the presence of Ca2+, exchanges Na+ for Ca2+. If the system is saturated with gypsum, loss of Ca2+ would …
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Novel Insights into the Hydrogeochemical Evolution of Groundwater within the Transboundary Milk River Aquifer
… young groundwater, elevated sulphate from pyrite oxidation, carbonate dissolution, cation exchange, and a Na-HCO₃-SO₄ water type. Zone 2, from 50–75 km, records sulphate depletion through bacterial sulphate reduction, organic matter oxidation, silicate dissolution, and transition to a …
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Les iguanodons de Bernissart: leur évolution diagénétique et les processus de dégradation
… and precipitated in the cavities during burial (pyrite, barite, sphalerite, celestine, iron oxi-hydroxides, authigenic apatite, calcium sulfate and to a lesser extent vivianite). Pyrite is the most abundant authigenic mineral in the Iguanodon fossil bones. It occurs in different morphologies …
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Inorganic hydrogeochemical responses to fires in wetland sediments on the Swan Coastal Plain, Western Australia
… such as drought and dewatering, have led to the oxidation of sediments, which has resulted in the acidification, base cation leaching and metal contamination of both ground- and surface-waters. The buffering capacity is strongly linked to the underlying geomorphology. Wetlands on the …
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Thermodynamic and kinetic studies of sulfur geochemistry
… sulfur species that occur during the aqueous oxidation of sulfide minerals, which identified at least one thermodynamically feasible pathway for the overall reaction. The data were also used to construct an EhpH diagram for aqueous sulfur species with average sulfur oxidation states less than …
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The Persistence of Acid Mine Drainage at an East Texas Coal Mine
… time it will take for acid forming materials (pyrite) to be weathered to a state of equilibrium and thus cease to produce acid in ground and surface waters within Oak Hill Mine. This was accomplished using an ex-situ kinetic leaching study incorporating a humidity cell in a controlled …
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Developing quantitative approaches to determine microbial colonisation and activity in mineral bioleaching and characterisation of acid rock drainage
… interactions with, and colonisation of, pyrite concentrates and pyrite bearing waste rocks. The assessment of these interactions was carried out in this study in a synergistic qualitative as well as quantitative manner, with a particular focus on heap bioleaching for metal extraction and …