O idation of pyrite in coal to magnetite

O idation of pyrite in coal to magnetite

Oxidation of pyrite in coal to magnetite ScienceDirect When bituminous coal is heated in an inert atmosphere (He) containing small amounts of oxygen at 393–455

  • Oxidation of pyrite in coal to magnetite ScienceDirect

    When bituminous coal is heated in an inert atmosphere (He) containing small amounts of oxygen at 393–455 °C, pyrite (FeS 2) in coal is partially converted to magnetite (Fe 3 0 4)The maximum amount of Fe 3 0 4 formed during the time of heating corresponds to 5–20% of the total pyrite present, depending on the coal sample The magnetite forms as an outer crust on the pyrite grainsWhen bituminous coal is heated in an inert atmosphere (He) containing small amounts of oxygen at 393455 ??C, pyrite (FeS2) in coal is partially converted to magnetite (Fe304) The maximum amount of Fe304 formed during the time of heating corresponds to 520% of the total pyrite present, depending on the coal sample The magnetite forms as an outer crust on the pyrite grainsOxidation of pyrite in coal to magnetite USGSA method for increasing the magnetization of pyritecontaining pulverized coal comprises heating the coal in an atmosphere of inert gas, desirably nitrogen, containing 3 to 60 torr, preferably 12 to 16 torr, partial pressure of air to a temperature in the range 390° to 455° C, desirably 400° to 410° C, for a time sufficient, preferably 2 minutes to 2 hours, for converting enough pyriteMethod for oxidation of pyrite in coal to magnetite and

  • o idation of pyrite in coal to magnetite

    Oxidation of pyrite in coal to magnetite ScienceDirect May 01, 1984· When bituminous coal is heated in an inert atmosphere (He) containing small amounts of oxygen at 393–455 °C, pyrite (FeS 2) in coal is partially converted to magnetite (Fe 3 0 4)The maximum amount of Fe 3 0 4 formed during the time of heating corresponds to 5–20% of the total pyrite present, depending on the coalA project was undertaken to characterize the oxidation of iron pyrite to the nonslagging species magnetite during pulverized coal combustion The work was aimed at defining the pyrite transformations responsible for the higher slagging propensity of staged, lowNO{sub x} pulverized coal combustor burners With such burners, coal is injected into a reducing environmentMechanisms of Pyrite Oxidation to NonSlagging SpeciesMechanisms of pyrite oxidation to nonslagging species Quarterly report, September 1September 30, 1994 This document is the first quarterly status report on a project concerned with enhancing the transformation of iron pyrite to nonslagging species during staged, lowNO {sub x} pulverized coal (PC) combustionMECHANISMS OF PYRITE OXIDATION TO NONSLAGGING

  • Thermal phase transition of pyrite from coal | SpringerLink

    The thermal phase transition of pyrite from coal was studied using thermogravimetry and derivative thermogravimetric, infrared spectroscopy and Xray diffraction (XRD) According to the XRD results, the phase transition of the pyrite starts at 350 °C, pyrrhotite and magnetite are intermediate products of the oxidation from pyrite to hematite It was proposed that the main gases and volatilePyrite Oxidation Kinetics – How Fast does Pyrite Oxidize Pyrite oxidation has been studied extensively, in the past, because of its importance in sulfide mineral separations by flotation, in the generation of acid in mine waters and in leaching of pyrite The oxidation of pyritePyrite Oxidation Kinetics How Fast does Pyrite OxidizePyrite has a significant effect on the spontaneous combustion of coal The presence of pyrite can change the propensity of coal towards spontaneous combustion The influences of various pyrite contents on the parameters of spontaneous combustion, such as index gases, temperature and released heat etc, were investigated in this study Coal samples with different pyriteEffects of pyrite on the spontaneous combustion of coal

  • AMD: Basic chemistry Lehigh University

    The first reaction in the weathering of pyrite includes the oxidation of pyrite by oxygen Sulfur is oxidized to sulfate and ferrous iron is released This reaction generates two moles of acidity for each mole of pyrite oxidized 2 FeS 2 + 7 O 2 + 2 H 2 O => 2 Fe 2+ + 4 SO 4 2+ 4 H +Oxidation of pyrite in coal to magnetite ScienceDirect May 01, 1984· When bituminous coal is heated in an inert atmosphere (He) containing small amounts of oxygen at 393–455 °C, pyrite (FeS 2) in coal is partially converted to magnetite (Fe 3 0 4)The maximum amount of Fe 3 0 4 formed during the time of heating corresponds to 5–20% of the total pyrite present, depending on the coalo idation of pyrite in coal to magnetitepyrite transformation to magnetite, finer grinding of the coal feed to liberate pyrite inclusions would enhance the rate of the overall pyrite conversion process In addition, smaller coalchar particles would have higher internal oxygen levels (higher effectiveness factors) and hence, pyrite inclusions would have higher rates of oxidationMECHANISMS OF PYRITE OXIDATION TO NON

  • Clay and pyrite transformations during ignition of

    Oxidation of pyrite leads to coating of cenospheres by condensed magnetite and the emission of sulphur dioxide in the flue gases Type Research Article Chemical composition and size of particles in emissions of a coalfired power plant with flue gas desulfurization Journal ofApplicability of the manometric method for studying the oxidation of pyritic material in the presence of bacteria has been demonstrated Resting cells of Ferrobacillus ferrooxidans accelerated the oxidation of coal pyrites and coarsely crystalline marcasite, but were inactive on coarsely crystalline pyriteBacterial Oxidation of Pyritic Materials in CoalThe US Department of Energy's Office of Scientific and Technical InformationMechanisms of pyrite oxidation to nonslagging species

  • The mechanisms of pyrite oxidation and leaching: A

    APChandra,ARGerson/SurfaceScienceReports65(2010)293–315 295 Table 1 Restpotentialofsomecommonsulfidemineralsdeterminedunderstandard conditionsAs a followup to previous gas analysis experiments in which pyrite was heated to 681 K in an anoxic (oxygen starved) atmosphere, the first oxidation product, FeSO4, was studied as a bulk material No decomposition of FeSO4 to Fe3O4 was observed in the temperature range studied The lack of decomposition of bulk FeSO4 to Fe3O4 suggests that FeS2 oxidizes directly to Fe3O4, or thatSuperparamagnetic Fe3O4 particles formed by oxidationPyrite has a significant effect on the spontaneous combustion of coal The presence of pyrite can change the propensity of coal towards spontaneous combustion The influences of various pyrite contents on the parameters of spontaneous combustion, such as index gases, temperature and released heat etc, were investigated in this study Coal samples with different pyriteEffects of pyrite on the spontaneous combustion of coal

  • The causes behind pyrite oxidation and acid mine

    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 phenomenonAbstract 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 perturbationThis perturbation, which results from land disturbancesA review: Pyrite oxidation mechanisms and acid mineOxidation of pyrite in coal to magnetite ScienceDirect May 01, 1984· When bituminous coal is heated in an inert atmosphere (He) containing small amounts of oxygen at 393–455 °C, pyrite (FeS 2) in coal is partially converted to magnetite (Fe 3 0 4)The maximum amount of Fe 3 0 4 formed during the time of heating corresponds to 5–20% of the total pyrite present, depending on the coalo idation of pyrite in coal to magnetite

  • MECHANISMS OF PYRITE OXIDATION TO NON

    pyrite transformation to magnetite, finer grinding of the coal feed to liberate pyrite inclusions would enhance the rate of the overall pyrite conversion process In addition, smaller coalchar particles would have higher internal oxygen levels (higher effectiveness factors) and hence, pyrite inclusions would have higher rates of oxidationApplicability of the manometric method for studying the oxidation of pyritic material in the presence of bacteria has been demonstrated Resting cells of Ferrobacillus ferrooxidans accelerated the oxidation of coal pyrites and coarsely crystalline marcasite, but were inactive on coarsely crystalline pyriteBacterial Oxidation of Pyritic Materials in CoalThe decomposition of pyrite was investigated in a thermo‐balance In neutral or reducing gases it decomposes between 550° and 700°C to volatile sulfur and ferrous sulfide In oxygen it oxidizes in two stages: between 445° and 520°C, it forms sulfur dioxide and ferrous sulfide: between 610° and 660°C it forms more sulfur dioxide and hematite’In air Or with fast cycles, the reactionsOxidation of Pyrite, Journal of the American Ceramic

  • Transformation of Pyrite and Its Implication on Ash

    Pyrite FeS 2 Magnetite Fe 3 O 4 Temperature, ºC HSC calculation 1 400500 ºC pyrite no significant decomposition 2 600 ºC pyrite & pyrrhotite significant decomposition 3 700800 ºC pyrrhotite stable phases 4 900 ºC pyrrhotite & Magnetite commencement of oxidationstantia during oxidation However, in similar tests conducted in the absence of water vapor, only a slight temperature rise was noted and the presence of sul­ fate on the surface was not detected Xray diffration sis The role that moisture has in pro­ is the not the oxidation of pyrite to sulfate understood However,Analysis of the Oxidation of Chalcopyrite,ChalcociteThe presence of pyrite in coal has been recognised as a contributing factor to selfheating for many years, but there has been no standard test developed that quantifies the effect (Miron, et al, 1992) The fundamental reaction for pyrite selfheating is described by Weise, Powell and Fyfe (1987) as: FeS 2 + 8H 2 O + 7O 2 → FeSO 47H 2University of Wollongong Research Online

  • 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 perturbationThis perturbation, which results from land disturbancespresence of calcareous minerals; acid produced by pyrite oxidation is neutralized The pH values in the acidic mode result from pyrite oxidation and imply a deficiency of calcareous minerals and the absence of carbonate buffering The oxidation of only a small quantity of pyrite can acidify pure water (0012 g·L1 FeS 2 produces pH~4 and 20 mgFrequency Distribution of the pH of CoalMine DrainageTo understand the behavior of pyrite (a key slaginducing coal mineral) in oxyfuel combustion (O 2 /CO 2 combustion), our previous work firstly investigated the effects of pure CO 2 on fixed bed reactors and at low temperatures (<1273 K) and long residence time (order of minutes)Hightemperature transformation of pyrite in CO2: Effects

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