Behaviour of iron-bearing minerals in the early stages of pulverised coal conversion processes

Vuthaluru, Hari; Eenkhoorn, S.; Hamburg, G.; Heere, P.G.T.; Kiel, J.H.A.

doi:10.1016/s0378-3820(98)00046-0

Cited by 12 publications

(6 citation statements)

References 12 publications

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“…Different species of elements as additives were also studied; i.e., four types of chemicals used for iron, including Fe 2 O 3 , FeS 2 , FeSO 4 (NH 4 )SO 4 ·6H 2 O, and NH 4 Fe(SO 4 ) 2 ·12H 2 O. The presence of pyrite in coal is believed to have a catalytic effect on the carbon−oxygen reaction and the ignition temperature is decreased, as found by several authors. − Fe 2 O 3 and Fe were the major products of iron-bearing minerals in early stages of coal conversion . In this study, the effects of adding FeS 2 were studied only for Jinzhushan and Laiyang coals, it was found that this species improves the ignition of both coals.…”

Section: Resultsmentioning

confidence: 92%

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Evaluation of Combustion Characteristics of Chinese High-Ash Coals

et al. 2003

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The combustion characteristics of four Chinese high-ash coals were evaluated by thermogravimetric and surface analysis. Changes in surface area and porosity during combustion were investigated with original (as-received) coals, coal samples before ignition, and chars after burnout. To understand the roles of various ash components, comparative experiments were carried out with as-received, de-ashed, and impregnated coals.

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Section: Resultsmentioning

confidence: 92%

“…[21][22][23] Fe 2 O 3 and Fe were the major products of iron-bearing minerals in early stages of coal conversion. 24 In this study, the effects of adding FeS 2 were studied only for Jinzhushan and Laiyang and also changes the overall porosity of coal, inhibiting the reaction.…”

Section: Combustion Of De-ashed Coalsmentioning

confidence: 99%

Evaluation of Combustion Characteristics of Chinese High-Ash Coals

et al. 2003

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“…It also reacts with clay minerals to form a molten Fe−Si−Al− O phase, which is contributed to ash deposition and slagging. 32 The existence of a fine particles layer could increase the diffusion resistance of corrosive gases inwards of the corrosion side and change the gas film diffusion mode into the couple mode of film diffusion and Knudsen diffusion. Gas components including H 2 S, O 2 , CO, and H 2 are identified as the major attacking species.…”

Section: Deposition Mechanism and Sulfide Corrosion Behaviormentioning

confidence: 99%

“…While under an oxidizing atmosphere, the excluded pyrite in coal is oxidized into hematite or magnetite. It also reacts with clay minerals to form a molten Fe–Si–Al–O phase, which is contributed to ash deposition and slagging …”

Section: Deposition Mechanism and Sulfide Corrosion Behaviormentioning

confidence: 99%

Formation of Sulfide Deposits and High-Temperature Corrosion Behavior at Fireside in a Coal-Fired Boiler

Wang

et al. 2020

Energy Fuels

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Because of adopting a high air-staging combustion ratio for Chinese coal-fired boilers, the water walls currently suffer from severe sulfidic corrosion and slagging. This work aims to understand the real deposition of ash particles and the hightemperature corrosion behavior at fireside, after making detailed characterizations for four types of deposits or slags and a corroded water-wall tube, which were collected from a real coal-fired boiler. The profile section of the corroded tube presents three layers with respective features. The major phases for the manually peeled layer from the corroded tube are identified as polymorphous pyrrhotite (Fe 7 S 8 , Fe 9 S 10 , Fe 1−x S), galena, and lead oxides. Above the corroded layer the deposits are mainly composed of ZnS-and Si−Al-rich phases, minor of Fe-rich particles. This is mainly attributed to the direct condensation of gaseous PbS or Pb, the sulfidation of gaseous Zn and Pb, and the thermophoretic deposition of ZnS-/Si−Al-rich fine particles. The impact and erosion of particles promote the splitting of the outer corrosion layer into small parts and then peeling off from the inner layer. Additionally, enrichments of various trace elements including As, Ge, Ga, Th, and Sn are attributed to the direct condensation of metal vapors and their revaporization−condensation from the unburnt particles. The oxidation and sulfidation of iron are competitive and responsible for continuous corrosion. Although Fe sulfidation can be suppressed in the regions in which either ZnO or PbO is stable, Fe can be sulfided or oxidized in the regions where ZnS or PbS is stable.

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“…on mineralogy and physical–chemical properties of the slag. In the practical production, as a result of the reducing condition (a synthesis gas of 30–60% CO, 25–30% H 2 , and 5–15% CO 2 ), iron-bearing minerals can be partially reduced to elemental iron eventually, which causes problems, such as slag port blockage . Because of the most abundant heterovalent component in coal ash/slag, the FeO x content has great influence on the slag properties, especially slag viscosity, relevant closely to slag tapping.…”

Section: Introductionmentioning

confidence: 99%

Mineralogy Study of the Effect of Iron-Bearing Minerals on Coal Ash Slagging during a High-Temperature Reducing Atmosphere

Xiong

Tang

et al. 2015

Energy Fuels

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Two typical Chinese high-rank coals with different iron contents, ZX coal from Zhenxiong, Yunnan province, and LY coal from Huaibei, Anhui province, were selected to study the effect of iron on ash behaviors at a high temperature in a reducing atmosphere. Two iron-bearing minerals (FeS 2 and Fe) were added to coals to change the C value (Fe 2 O 3 /CaO) and prepare different series of ash slag samples. X-ray fluorescence (XRF) spectrometer, X-ray diffractometer (XRD), and FactSage were employed to study the chemical composition, crystal mineral compositions, and mineral transformation process. The effect of iron-bearing minerals on the liquidus temperature (LT) and C value of the liquid phase in slag system was discussed. The results show that two intermediates, iron carbide (Fe 3 C) and ferrosilicate (Fe 2.56 Si 0.44 O 4 ), are found in slag samples when FeS 2 was added to LY and ZX coals. The diffraction peak intensity of Fe 3 C decreases with the temperature increasing from 900 to 1000 °C, and that of Fe 2.56 Si 0.44 O 4 decreases from 1200 to 1300 °C. However, neither of the two minerals is found in slag samples with the addition of iron powder in coals. In comparison to that of the raw coal slag, the LT calculated by FactSage software of each slag sample decreases with the addition of iron-bearing minerals. The more the high-melting-point mineral is crystallized, the higher the LT. As iron-bearing mineral and/or calcium-bearing mineral behaviors (melting, transforming, or crystallizing) change with the temperature increasing, a complicated nonlinear correlation between the C value and slagging temperature is obtained.

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Behaviour of iron-bearing minerals in the early stages of pulverised coal conversion processes

Cited by 12 publications

References 12 publications

Evaluation of Combustion Characteristics of Chinese High-Ash Coals

Evaluation of Combustion Characteristics of Chinese High-Ash Coals

Formation of Sulfide Deposits and High-Temperature Corrosion Behavior at Fireside in a Coal-Fired Boiler

Mineralogy Study of the Effect of Iron-Bearing Minerals on Coal Ash Slagging during a High-Temperature Reducing Atmosphere

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