Oxidation of pyrite in coal to magnetite ScienceDirect
The fact that the magnetic properties of the pyrite grains are substantially increased by the magnetite crust suggests that pyrite can be separated from coal by use of a low magnetic field. In a laboratory test, > 75% removal is obtained by means of a 500 Oe Oxidation of pyrite in coal to magnetite @article{Thorpe1984OxidationOP, title={Oxidation of pyrite in coal to magnetite}, author={Arthur N. Thorpe and Frank E. Senftle and Corrine Oxidation of pyrite in coal to magnetite Semantic Scholar
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Thermal decomposition and oxidation of pyrite with different
The pyrites can be oxidized to nano-hematite when heated in an air atmosphere at above 400–500 °C, with the transformation proceeding in the sequence of 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 Thermal phase transition of pyrite from coal SpringerLink
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Experimental Study on the Oxidation Reaction of
As one of the crucial factors contributing to coal spontaneous combustion, the oxidation of pyrite is a complex process involving multiple reactions, particularly in the presence of oxidants The formation of magnetite during the direct oxidation of pyrite is expected to be limited, as the oxidation of pyrite can only take place at temperatures lower than Decomposition and oxidation of pyrite ScienceDirect
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Oxidation of pyrite in coal to magnetite (Journal Article)
Made available by U.S. Department of Energy Office of Scientific and Technical InformationWhen bituminous coal is heated in an inert atmosphere (He) containing small amounts of oxygen at 393-455 ??C, pyrite (FeS2) in coal is partially converted to magnetite (Fe304). Oxidation of pyrite in coal to magnetite ScienceBase-Catalog
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The late diagenetic conversion of pyrite to magnetite by
It has been recently hypothe- sized that one likely chemical pathway for the late stage diagenetic conversion of pyrite to magnetite involves the oxidation of pyrite by It has been recently hypothe- sized that one likely chemical pathway for the late stage diagenetic conversion of pyrite to magnetite involves the oxidation of pyrite by Fe(III) complexed to organic ligands (Brothers et al., 1994). Magnetic properties and metastability of greigite-smythite mineralization in brown-coal basins of the KrusneThe late diagenetic conversion of pyrite to magnetite by
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Review on the Oxidation Behaviors and Kinetics of
The oxidation of magnetite is an exothermic reaction, generating considerable heat, which in turn helps to reduce the primary energy. [16, 17] Rarely literature quantitatively evaluated the exothermic Semantic Scholar extracted view of "Oxidation of pyrite in coal to magnetite" by A. Thorpe et al. Skip to search form Skip to main content Skip to account menu. Semantic Scholar's Logo. Search 213,950,741 papers from all fields of science. Search. Sign In Create Free Account.Oxidation of pyrite in coal to magnetite Semantic Scholar
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Iron removal from kaolinitic coal gangue via magnetic
After magnetic separation, the Fe 2 O 3 content decreased from 5.58% for the raw gangue to 1.00% for the nonmagnetic products of gangues calcined for 60–120 min. Retention of the strongly magnetic magnetite, which was an intermediate product in the oxidation of pyrite to hematite, enabled the effective removal of iron from the gangueWhen bituminous coal is heated in an inert atmosphere (He) containing small amounts of oxygen at 393-455 ??C, pyrite (FeS2) in coal is partially converted to magnetite (Fe304). The maximum amount of Fe304 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 Oxidation of pyrite in coal to magnetite ScienceBase-Catalog
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Oxidation of Pyrite Semantic Scholar
The 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 Stoichiometric magnetite (Fe 3 O 4) contains one divalent iron atom while the other two are trivalent.This compound has a face centred cubic inverse spinel structure and belongs to the space group Fd m.The ferrous ions occupy half the octahedral sites, while the ferric ions are evenly situated at both octahedral and tetrahedral sites.Mechanism and kinetics of magnetite oxidation under
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Mechanism and kinetics of magnetite oxidation under
bipyramidal or rhombohedral morphology. The oxidation kinetics was consistent with a diffusion controlled process. The reaction probably proceeded via the outward diffusion of ferrous ions from the magnetite, forming a magnetite/maghemite core/shell structure in conjunction with the dissolution of maghemite and reprecipitation of hematite.The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H<sub>2</sub>SO<sub>4</sub> solution had been investigated by using the open-circuit potential (OCP), cyclic voltammetry (CV), potentiodynamic polarization, and electrochemical impedance (EIS), respectively. Experimental results indicate that TETA Pyrite Passivation by Triethylenetetramine: An
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A. THORPE Howard University, DC HU Department of
Oxidation of pyrite in coal to magnetite. Article. May 1984; A. N. Thorpe; (He) containing small amounts of oxygen at 393–455 °C, pyrite (FeS2) in coal is partially converted to magnetiteThe oxidation of pyrite in an air atmosphere has been studied using Fourier transform infrared (FTIR) spectroscopy to identify phases present in the temperature range 430–680°C. Evidence of the formation of sulfate was obtained; the species was identified mainly as anhydrous iron (II) sulfate by comparison with the spectra of various A Fourier transform infrared study of the oxidation of pyrite
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Investigation on the transformation behaviours of Fe
This amount is approximately the same (34%) in the iron-containing clay minerals and significantly lower for jarosite (10.8%). In general, the oxidation of pyrite, during coal weathering, storage and transportation affords XFe 3 (OH) 6 (SO 4) 2 (jarosite), where X stands for H +, K +, Na + or NH 4 +. 26,27. 3.2. Mineral phases of ashes producedA standardized and calibrated heating system can thus be used to measure the pyrite content of coal specimens4. During coal burning, it is important to know the mechanism of formation of magnetite from pyrite during the coal gasification phase, because magnetite is a significant ingredient in the slag.Superparamagnetic Fe3O4 particles formed by oxidation of pyrite
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MECHANISMS OF PYRITE OXIDATION TO NON-SLAGGING
A project was undertaken to characterize the oxidation of iron pyrite to the non-slagging species magnetite during pulverized coal combustion. The work was aimed at defining the pyrite transformations responsible for the higher slagging propensity of staged, low-NO {sub x} pulverized coal combustor burners. With such burners, coal is injectedThe results showed that pyrite was transformed into hematite nanospheres during coal gangue combustion in air and released SO 2 gas in the process. The transformation proceeds in the sequence of pyrite (0 ∼ 400 °C) nano-microspheric magnetite and jarosite (400 ∼ 500 °C) nano-microspheric hematite (500 ∼ 1000 °C).The effect of experimental variables on the mechanism of the oxidation
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A kinetic model for pyrite transformations in a
A kinetic model for describing the transformations of excluded pyrite (FeS 2) particles in a combustion environment is developed by solving the particle heat and mass balances.The model follows the particle composition history, starting from pyrite decomposition to pyrrhotite (Fe 1 − x S), and its subsequent oxidation to a molten Made available by U.S. Department of Energy Office of Scientific and Technical InformationOxidation of pyrite in coal to magnetite (Journal Article)
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ofYangquan coal induced by electrochemical oxidation
In order to accelerate the electrochemical oxidation of pyrite in coal, a dia-phragmless electrolysis experiment was prepared by ourselves. e experimental steps are as follows: ① AddWhen 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 The magnetic separation of mineral slurries by a cryogenic
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In situ high-temperature phase transformation studies on pyrite
Compared to feed coal, minerals like hematite, hercynite, magnetite, and mullite are newly formed in combustion products. The formation of hematite and magnetite were mainly from the decomposition
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