pyrite formation rate
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- pyrite formation rate
For example, recent studies showed that the high sedimentation rates are conducive to the formation of the relative "closed" diagenetic system, leading to the formation of isotopically "heavy" pyrite (Pasquier et al., 2017; Liu et al., 2019). Other processes that may cause the enrichment of 34 S in pyrite are as follows.
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The onset of pyrite formation was found to significantly differ as a function of the TE added in the starting solution (Fig. 1), as revealed by powder XRD analyses of the solids collected over the course of the syntheses (Figs. 2 and SI-1–SI-10).Pyrite was detected after 235 h in the control experiment (Fe-S) and was fully formed after 330 h …
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Pyrite floatability with 1 × 10 −4 mol/L sodium isopropyl xanthate as a function of pH in the absence and presence of various initial concentrations of dextrin [1 g of pure pyrite ore with a nitrogen flow rate of 30 mL/min. Deionized water was used, adjusting the pH with dilute solutions of NaOH and HNO 3] (adapted from Valdivieso et al. ).
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January 01, 2004. Cite. Share. Permissions. The mechanisms of pyrite formation are reviewed. Advances since 1994 in our understanding of the mechanisms and rate of …
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Acid/Base Balance and Reaction Rates ... Drainage and spoil quality is a product of two competing processes: acid formation from pyrite oxidation, and generation of alkalinity from dissolution of carbonates and other basic minerals. The acid generation process consists of three phases: initiation; propagation; and termination. ...
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In situ rates of pyrite formation depend on a wide range of environmental conditions (Burton et al., 2011). The availability of sulfate, organic carbon, and reactive iron are key factors controlling pyrite formation in coastal sediments (Berner, 1970, 1984; Figure 1). In blue carbon ecosystems, tidal seawater inundation
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The study of sulfur isotope of authigenic pyrite in the mud area of the inner shelf of the East China Sea provides a good example for depositional control on the formation of authigenic pyrite and ...
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Pyrite seldom forms in fresh-water environments. The formation of pyrite crystals depends mainly on the iron content of the sediment. The process of pyrite formation in sediments results from the action of bacteria, which …
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For example, pyrite formation proceeds in some cases via the activity of microbial consortia (Thiel et al., 2019), and the rate of its formation and/or the formation of its precursor compounds may be enhanced by the availability of microbial biomass as a template or nucleation site for crystallization (Donald & Southam, 1999; Ferris et al ...
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The modelled glacial pyrite oxidation rate of 0.5–1.5 Pmol kyr −1 suggests that during glacial maxima, pyrite weathering rates on shelves were up to 2.3 times higher than the current ...
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Sediment reworking, therefore, leads to a higher pyrite oxidation rate than under normal marine deposition. ... –H), providing ideal conditions for pyrite formation (avg = 0.9 ± 0.2 wt.%) in the storm deposit. On the other hand, pyrite formation in freshwater sediments is severely limited by low concentrations of sulfate (Berner, 1984) ...
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High burial (and bioturbation) rates enable reactive compounds to become available for sulphate reduction, at depth, which otherwise would be destroyed by molecular oxygen at or above the sediment-water interface. An important consequence of bacterial sulphate reduction is the formation of sedimentary pyrite, FeS 2. In normal marine sediments ...
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Regression model for the oxidation rate of pyrite as a function of the concentration of dissolved Fe 3+ and Fe 2+ in oxygenated solutions from Williamson and Rimstidt (1994). ... 1995), but the difference in the free energy of formation of marcasite and pyrite is only 1.7 kJ/mol, or ∼0.14% of this total. Thus, there is only a tiny difference ...
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Fe-hydroxide formation, i.e., oxidative dissolution on a pyrite surface, is a kinetically control reaction; thus, this study investigated the short-term pyrite oxidation rate (~ 360 min) and the influence of the copresence of Ca and Mg under alkaline pH conditions (9, 10.5, and 12) as a fundamental study to establish optimal flotation and/or ...
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Experimental and field studies have suggested that large framboidal pyrite grains typically form in sulfide-rich environments and associated with rapid rates of pyrite formation, whereas euhedral pyrite grains form in settings where sulfide concentrations are lower and pyrite formation rates are slower (20–22).
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Pyrite is a common mineral in sedimentary rocks and is widely distributed in a variety of different morphologies and sizes. Pyrite is also widely distributed in the Es3x shale of the Eocene Shahejie …
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The formation of pyrite was promoted by the interaction of natural siderite [Fe 0.6–0.9 (Mn,Mg) 0.1–0.4 CO 3] ... Samples were ablated with spot sizes between 20 and 40 μm for 30 s, with a repetition rate of 10 Hz and an energy density of 2 to 3 J/cm 2. The data were reduced with the commercial software Iolite ...
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In this study, we have performed syntheses of pyrite at low temperature by the polysulfide pathway using aqueous Fe (III) and H2S in the presence of trace amounts of Ni (II) (0.001 mol%Fe) and As ...
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The formation of magnetite at temperatures lower than the equilibrium temperature for the Fe–O 2 system is probably due to the oxygen deficiency at the reaction front that is caused by the relatively high reaction rate of the oxidation of pyrite/pyrrhotite and the low diffusion rate of oxygen under certain reaction conditions.
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Field occurrence of pyrite nodules. The Doushantuo Formation in the South China Block directly overlies the Nantuo glacial diamictite and consists of as much as 250 m of carbonates, siltstones ...
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In this study, pyrite is precipitated at 80 °C in batch reactors through the H 2 S and polysulfide pathways, in which the precipitation rates and the concurrent formation of a greigite (Fe 3 S 4 ...
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Con- versely, the relatively high rates of pyrite formation during the Cambrian and Ordovician periods can be correlated with relatively low average rates of con- temporaneous formation of evaporites, at least dur- ing the Ordovician (RONOV, 1976; HOLSER, pers. commun.). Fluctuations in the C/S ratio, as shown in Fig. 5, are another …
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Therefore, the formation rate of pyrite in the metal-AOM zone can be much lower than that in SMTZ accordingly, framboidal pyrite in the metal-AOM zone is supposed to have a relatively small size as compared with euhedral pyrite. However, there are still many questions to be addressed about the material supply, and microbial participation ...
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The release rate of S from pyrite reflects its crystal structure characteristics. ... Banerjee A, Sood S. Thermal analysis of basic ferric sulphate and its formation during oxidation of iron pyrite. Therm Anal. 1982;1:769–74. CAS Google Scholar
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Pyrite scale formation is a critical problem in the hydrocarbon production industry; it affects the flow of hydrocarbon within the reservoir and the surface facilities. Treatments with inorganic ...
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The sedimentation rate, reported as cm/yr, was calculated by dividing the thickness of sediment intervals (excluding event layers) between 14 age control points by their time duration ... For example, the formation of pyrite in the SMTZ leads to a rapid decline in magnetic susceptibility (Riedinger et al., ...
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As the rate of sulfate supply decreases relative to the rates of sulfate reduction and pyrite formation, for example in more deeply buried sediments, environments tend to record smaller differences between the δ 34 S values of seawater sulfate and sedimentary pyrite (Zaback et al., 1993, Fike et al., 2015, Liu et al., 2021).
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Pyrite has completely oxidized throughout the layer of thickness L b, except in the bottom ~1-m-thick depth interval (l b) located about 1.5 to 3.5 m above the water table, where oxidation and formation of pseudomorphs are ongoing (Fig. 1A and fig. S2). We determined the change in fractional extent of oxidation versus depth across l b.
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Pyrite, or iron disulfide, is the most common sulfide mineral on the Earth's surface and is widespread through the geological record. Because sulfides are mainly produced by sulfate-reducing bacteria (SRB) in modern …
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This difference in pyrite formation kinetics is further demonstrated by Fe K-edge EXAFS spectroscopy analysis of the solid samples formed over the course of the batch synthesis experiments, as detailed hereafter.The unfiltered k 3-weighted Fe K-edge EXAFS spectra of the solids sampled over time in the Fe-S, Fe-S:Ni and Fe-S:As batch …
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