Mineral behavior during coal combustion 1. Pyrite transformations

Srinivasachar, S.; Helble, J.J.; Boni, A.A.

doi:10.1016/0360-1285(90)90037-4

Cited by 138 publications

(124 citation statements)

References 8 publications

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“…This is due to oxidation of pyrite and szomolnokite in the coal during the burning. A number of studies had been done to investigate the decomposition of pyrite and szomolnokite in coal [10,12,16,17]. There are different reaction schemes by which these transformations can be explained.…”

Section: Mössbauer Examinationmentioning

confidence: 98%

Study of Kinetics of Iron Minerals in Coal by 57Fe Mössbauer and FT-IR Spectroscopy During Natural Burning

Bandyopadhyay

2006

Hyperfine Interact

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The process of burning of sulphur rich coal from Jaipur mine in NorthEastern India was carried out at a temperature of (675 ± 5) • C for different time intervals. 57 Fe Mössbauer spectroscopy was applied to study the reaction products of iron compounds in each step of thermal treatment. The transformation of Szomolnokite (FeSO 4• H 2 O) and Pyrite (FeS 2 ) in the as received coal sample finally transformed to γ -Fe 2 O 3 and α-Fe 2 O 3 . Other clay minerals produce some low spin silicate ash. Fourier Transmission Infrared (FT-IR) spectroscopy gives the ratio of several structural parameters such as H ar /H al and H ar /C ar . DTA analysis of the coal sample gives the exothermic reaction at different temperatures. TGA and TG analysis of the coal sample in an inert atmosphere shows the weight loss of the coal sample in different temperature ranges.

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Section: Mössbauer Examinationmentioning

confidence: 98%

Study of Kinetics of Iron Minerals in Coal by 57Fe Mössbauer and FT-IR Spectroscopy During Natural Burning

Bandyopadhyay

2006

Hyperfine Interact

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“…Iron in non-combusted particles may have been present as part of the crystallised aluminosilicate composition, whereas partially combusted particles have been suggested to have an important magnetite (Fe 3 O 4 ) fraction, as shown in Eqn 6. [46] In all these cases, the composition of the sample includes Fe 2þ . Because the content of iron in EUFA was not necessarily in an oxide form, the initial rate was the result of a combination of Eqn 10 and the leaching of iron content in noncombusted particles.…”

Section: Iron Leach Experimentsmentioning

confidence: 99%

Comparative evaluation of iron leach from different sources of fly ash under atmospherically relevant conditions

et al. 2016

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Environmental context. Iron, a limiting nutrient of plankton in the ocean, is deposited to the sea from atmospheric aerosols. In particular, atmospheric acidic conditions promote dissolution of iron from fly ash, a byproduct of coal-fired power plants. Here, we report that the iron leached from fly ash depends on its source region, and that the type of combustion process may influence the iron species mobilized.Abstract. Fly ash, an iron-containing by-product of coal-fired power plants, has been observed in atmospheric aerosol plumes. Under the acidic atmospheric conditions resulting from the uptake of atmospheric gases, iron leached from fly ash can impact global biogeochemical cycles. However, the fly ash source region, as well as its generating power plant, plays an important role in the amount, speciation and lability of iron. Yet no comparative studies have been made on iron leached from fly ash from different sources. This study reports the iron mobilisation by proton-promoted dissolution from wellcharacterised fly ash samples from three distinctive locations: the USA Midwest, north-east India and Europe. In addition, pH dependency was also investigated. Proton-promoted dissolution showed a variability between source regions with a relative iron leach in the order USA Midwestern . north-east Indian . European ash. In addition, the initial rate of iron leach suggests that source region is indeed a determining factor in the iron leaching capacity of fly ash, because dissolution from Midwestern fly ash is also faster than both European and Indian ash. Finally, the combustion process of fly ash proved to be significant for the iron speciation, given that well-combusted fly ash samples leached mostly Fe 3þ rather than bioavailable Fe 2þ . The role of fly ash should therefore be taken into account in order to better understand the effects of combustion particles in atmospheric iron deposition.

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“…Both coal samples were primarily pulverized into fine particles with diameters less than 100 µm, and then combusted in a muffle furnace at 800 °C for 2 h. For temperatures lower than 800 °C, no chemical reactions other than decomposition occurred among the minerals of the coal ashes [34]. Therefore, the blended ashes were prepared by hand-mixing of the G coal ash with the D coal ash obtained at 800 °C at five blending ratios: G:D = 10:90 (G10D90), G:D= 20:80 (G20D80), G:D = 30:70 (G30D70), G:D = 40:60 (G40D60), and G:D = 50:50 (G50D50).…”

Section: Coal and Ash Samplesmentioning

confidence: 99%

Influence of Coal Blending on Ash Fusibility in Reducing Atmosphere

et al. 2015

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Abstract:Coal blending is an effective way to organize and control coal ash fusibility to meet different requirements of Coal-fired power plants. This study investigates three different eutectic processes and explains the mechanism of how coal blending affects ash fusibility. The blended ashes were prepared by hand-mixing two raw coal ashes at five blending ratios, G:D = 10:90 (G10D90), G:D= 20:80 (G20D80), G:D = 30:70 (G30D70), G:D = 40:60 (G40D60), and G:D = 50:50 (G50D50). The samples were heated at 900 °C, 1000 °C, 1100 °C, 1200 °C, and 1300 °C in reducing atmosphere. XRD and SEM/EDX were used to identify mineral transformations and eutectic processes. The eutectic processes were finally simulated with FactSage. Results show that the fusion temperatures of the blended ashes initially decrease and then increase with the blending ratio, a trend that is typical of eutectic melting. Eutectic phenomena are observed in D100, G10D90, and G30D70 in different degrees, which do not appear in G100 and G50D50 for the lack of eutectic reactants. The main eutectic reactants are gehlenite, magnetite, merwinite, and diopside. The FactSage simulation results show that the content discrepancy of merwinite and diopside in the ashes causes the inconsistent eutectic temperatures and eutectic degrees, in turn decrease the fusion temperature of the blended ash and then increase them with the blending ratio. OPEN ACCESSEnergies 2015, 8 4736

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Mineral behavior during coal combustion 1. Pyrite transformations

Cited by 138 publications

References 8 publications

Study of Kinetics of Iron Minerals in Coal by 57Fe Mössbauer and FT-IR Spectroscopy During Natural Burning

Study of Kinetics of Iron Minerals in Coal by 57Fe Mössbauer and FT-IR Spectroscopy During Natural Burning

Comparative evaluation of iron leach from different sources of fly ash under atmospherically relevant conditions

Influence of Coal Blending on Ash Fusibility in Reducing Atmosphere

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