(PDF) Pyrite dissolution in acidic media | Pierre Vitorge ...

Pyrite surfaces free of any oxida- oxidation numbers from (⫺I), as in FeS2, to (⫹VI), as tion products were dissolved in acidic media to avoid iron in SO2⫺ 4 . hydrolysis and precipitation, and sulfur and iron aqueous Williamson and Rimstidt (1994) have compiled data from speciation was monitored.

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Role of pyrite in formation of hydroxyl radicals in coal ...

Pyrite has recently been shown to spontaneously generate hydrogen peroxide (H 2 O 2) [32, 33] and hydroxyl radicals (• OH) [23, 24] when placed in water.The formation of these reactive oxygen species (ROS) also explains the recent observation that aqueous pyrite slurries degrade yeast RNA, ribosomal RNA, and DNA [].Pyrite is thought to form H 2 O 2 through the iron-catalyzed Haber …

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Mechanisms of sedimentary pyrite formation | Request PDF

The formation mechanism of sedimentary (including nodular) pyrite is still a matter of debate [5] [6][7]. Recent studies of syngenetic and diagenetic pyrite from black shales have showed that ...

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Formation of diagenetic concretions: Figure 1. Pyrite ...

Formation of insoluble pyrite lowered the concentrations of both reacting components establish-ing a precipitation-driven diffusion process. The pre- ... spectively offer possible mechanisms for concretionary growth. In both cases the concretion would have con-sisted of a precursor of the current mineral composi-

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Role of cation diffusion in the formation mechanism and ...

Cobalt-doped pyrite thin films have been prepared and their formation mechanism has been investigated through the measurement of their structure, composition (using a variety of experimental techniques), and transport properties (Seebeck and electrical resistivity). As a result, a simultaneous formation and doping mechanism is described.

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The formation mechanisms of sedimentary pyrite nodules ...

The U.S. Department of Energy's Office of Scientific and Technical Information

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Presentation on mechanisms and applications of ...

The new development of mechanism research, enhanced and intensified technologies on the bioleaching of chalcopyrite and pyrite, are conducted and summarized from the different branches of natural science. Some are depicted and explained based on molecular level in this paper.

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(PDF) Pyrite framboids and their development: a new ...

Trapping mechanisms include i) complexation (i.e. uranyl-carboxyl complexes), ii) adsorption on organic or clay particles) and iii) reduction by pyrite and by bacterial activity to amorphous ...

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PYRITE OXIDATION and ITS CONTROL

4.1 Pyrite Occurrence, Formation, Morphology and Chemistry 77 4.2 Transitional Metal-Pyrite Oxidation 82 4.2.1 Effect of ferric hydroxide species on pyrite oxidation. 83 ... 6.3.2 Electrochemical mechanisms of pyrite oxidation 147. 6.4 Pyrite Surface Functional Groups 148

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Greigite: a true intermediate on the polysulfide pathway ...

The formation of pyrite (FeS 2) from iron monosulfide precursors in anoxic sediments has been suggested to proceed via mackinawite (FeS) and greigite (Fe 3 S 4).Despite decades of research, the mechanisms of pyrite formation are not sufficiently understood because solid and dissolved intermediates are oxygen-sensitive and poorly crystalline and therefore notoriously difficult …

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Pyrite: Mineral information, data and localities.

Pyrite Group. The isometric (cubic) polymorph of orthorhombic marcasite.Compare UM1997-43-S:Fe. Pyrite is a very common mineral (also one of the most common natural sulfides, and the most common disulfide), found in a wide variety of geological formations from sedimentary deposits to hydrothermal veins and as a constituent of metamorphic rocks.The brassy-yellow metallic colour of pyrite has in ...

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Minerals | Free Full-Text | Pyrite Morphology as an ...

According to the different formation mechanisms of diagenetic pyrite, early diagenetic pyrites are formed in the sediments' porewater when the location of the oxic-anoxic interface falls down to the sediment (the diameter of an early diagenetic framboid is larger than 5 µm with a broad size distribution) (Figure 1b) [13,22,25,26].

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Mechanisms of interaction between arsenian pyrite and ...

The oxidation of pyrite is usually accompanied by the formation of active oxygen species including OH and H 2 O 2 (Borda et al., 2003, Zhang et al., 2016). In order to examine the possible effect of OH on the oxidation processes, ethanol was added to the reaction system of 0–1.0 mmol L −1 As(III) and 1.0 g L −1 arsenian pyrite to reach a ...

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The formation mechanisms of sedimentary pyrite nodules ...

View more > Redox sensitive trace elements in pyrite, including nodules, are increasingly used to infer the chemical conditions of ancient oceans—but considerable uncertainty remains regarding the mechanism and timing of nodule formation. Resolving these uncertainties is important because pyrite nodules must form in connection with the ...

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Pyrite - an overview | ScienceDirect Topics

D. Rickard, in Treatise on Geochemistry (Second Edition), 2014 9.10.3.2 Mechanisms of Pyrite Formation. Pyrite formation involves two distinct processes: pyrite nucleation and pyrite crystal growth. In experimental studies of the kinetics of pyrite formation in sediments, the process being studied by conventional kinetic methods is necessarily pyrite crystal growth.

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24. FRAMBOIDAL PYRITE IN DEEP-SEA SEDIMENTS Federal ...

amined by scanning electron microscopy (SEM). In foraminifer-nannofossil-diatom oozes, pyrite framboids occur on-ly as assemblages in microfossils forming a separate microenvironment, whereas in black slhales they occur throughout the sediment. The formation mechanism of the framboids is reviewed, but many questions still exist. INTRODUCTION

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Mechanisms of sedimentary pyrite formation | Request PDF

The mechanisms of pyrite formation are reviewed. Advances since 1994 in our understanding of the mechanisms and rate of pyrite formation, the role of bacteria in the formation of pyrite, framboid ...

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Mechanisms and rates of pyrite formation from hydrothermal ...

Two-step mechanism of pyrite formation and equilibration between the mineral and hydrothermal fluid controlled by Fe(II) aqueous species, revealed by Fe isotopes in this study at 400–450 °C and from analyses of literature data in the T range of 300–350 °C. Note the X-axis break at > 50 days to enable better visualization.

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Response to Comment on "Abiotic Pyrite Formation Produces ...

We entirely agree, and it seemed intuitive that where pyrite is a minor species, the bulk composition will not reflect the fractionation associated with its formation but another mechanism. The Fe isotope values plotted in figure 3 of our paper represent pyrite grains and nodules from ( 3 ) and not bulk black shales.

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Kinetics and Mechanism of Pyrite Formation at Low ...

The kinetics of pyrite formation in the reaction between FeS, sulfur, and hydrogen sulfide in aqueous solution have been investigated between 20 degree and 50 degree C and at 1 atm pressure. The kinetics were followed by timed analyses of pyrite concentrations for a series of experimental runs with varying initial reactant concentrations.

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Mechanisms of sedimentary pyrite formation -

The mechanisms of pyrite formation are reviewed. Advances since 1994 in our understanding of the mechanisms and rate of pyrite formation, the role of bacteria in the formation of pyrite, framboid formation, and incorporation of impurities into pyrite are emphasized. Both field studies as well as laboratory studies designed to better represent ...

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(PDF) Mechanisms of sedimentary pyrite formation | Martin ...

Sedimentary pyrite formation is the mechanism of pyrite formation and specifically to derive reac- by no means restricted to marine coastal environments, although tion rates, there are still some significant gaps in our knowledge. that is where most sedimentary pyrite is formed.

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A review: Pyrite oxidation mechanisms and acid mine ...

Abstract. Sulfide oxidation, part of sulfur's biotic/abiotic cycle, is an important natural phenomenon. However, because of the sulfide's association with metallic ores and fossil fuels in the form of pyrite (FeS 2) and the world's increasing demand for metals and fossil fuels, sulfide oxidation in nature is in some state of perturbation.This perturbation, which results from land disturbances ...

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Mechanisms and rates of pyrite formation from hydrothermal ...

Mechanisms and rates of pyrite formation from hydrothermal fluid revealed by iron isotopes. Author links open overlay panel Gleb S. Pokrovski Marc Blanchard Gaëlle ... The lack of isotope equilibrium between fluid and pyrite in this study and other recent work demonstrates that the fluid-pyrite Fe isotope exchange is kinetically controlled ...

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Mechanism of Sulfur Oxidation in Pyrite

Mechanism of Sulfur Oxidation in Pyrite. Post navigation. ... The change in electrochemical behavior on repeated scanning is associated with formation of intermediates during oxidation. For the cathodic peak, the parameter βC remained constant at 0.044 V, except for the first cycle. In the first negative-going scan, the cathodic process is ...

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The formation mechanisms of sedimentary pyrite nodules ...

Pyrite formation depends on three main mechanisms that are sensitive to the concentrations and sources of S and the pH of the solution: (1) H 2 S + FeS → FeS 2(pyrite) + H 2 ( Rickard, 1997, Rickard and Luther, 1997 )

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Experimental study of formation mechanisms of hydrothermal ...

Hydrothermal experiments were performed to synthesize pyrite crystals in the system HCl + NaCl + Fe 1- x S + H 2 O ± CaSO 4, in sealed silica capsules at temperatures between 150 and 350°C, for periods of up to eight weeks. The Fe 2+ and H 2 S (aq) necessary for the nucleation and growth of the pyrite crystals were generated in situ in the capsules, by the reaction of HCl with pyrrhotite ...

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Pyrite formation from FeS and H2S is mediated by a novel ...

61 iron, sulfur, and carbon cycles as well as Earth's surface redox state, the mechanism of pyrite 62 formation in natural environments is still being debated (1). Currently, two mechanisms are 63 discussed to drive pyrite formation in sediments, which both preclude dissolution of

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[PDF] Adsorption mechanism of copper xanthate on pyrite ...

DOI: 10.37190/PPMP/135131 Corpus ID: 233603905. Adsorption mechanism of copper xanthate on pyrite surfaces @article{Deng2021AdsorptionMO, title={Adsorption mechanism of copper xanthate on pyrite surfaces}, author={Zheng Bin Deng and Wanli Cheng and Yun Tang and Xiong Tong and Zhihong Liu}, journal={Physicochemical Problems of Mineral Processing}, year={2021}, volume={57}, …

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Pyrite Oxidation Kinetics - How Fast does Pyrite Oxidize

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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