Refinement of iron ore sinter phases: a silico-ferrite of calcium and aluminium (SFCA) and an Al-free SFC, and the effect on phase quantification by X-ray diffraction

Kahlenberg, Volker; Liles, David C.; Villiers, J. P. R. de

doi:10.1007/s00710-015-0411-5

Cited by 25 publications

(18 citation statements)

References 8 publications

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“…Quantitative phase analysis was achieved using the Rietveld method [15] with the software TOPAS V5 (Bruker AXS, Madison, Wisconsin, USA [16]). The crystal structure information used as the basis for the refinement was taken from Blake et al [17] for hematite, Hamilton [18] for magnetite, Hamilton et al [6] and Liles et al [19] for SFCA and Tsurumi et al [20] for C2S. The Rietveld method directly reports the relative weight fractions of all crystalline phases included in the model, which thus sum to 100%; the approach taken here to calculate the absolute weight fractions and thus also the amorphous/unidentified phase content was a traditional external standard approach [21], using corundum (Baikalox Regular product-CR1, Baikowski, Charlotte, NC, USA) as the external standard.…”

Section: Quantitative X-ray Diffractionmentioning

confidence: 99%

Comparison of the Mineralogy of Iron Ore Sinters Using a Range of Techniques

et al. 2019

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Many different approaches have been used in the past to characterise iron ore sinter mineralogy to predict sinter quality and elucidate the impacts of iron ore characteristics and process variables on the mechanisms of sintering. This paper compares the mineralogy of three sinter samples with binary basicities (mass ratio of CaO/SiO 2 ) between 1.7 and 2.0. The measurement techniques used were optical image analysis and point counting (PC), quantitative X-ray diffraction (QXRD) and two different scanning electron microscopy systems, namely, Quantitative Evaluation of Materials by Scanning Electron Microscopy (QEMSCAN) and TESCAN Integrated Mineral Analyser (TIMA). Each technique has its advantages and disadvantages depending on the objectives of the measurement, with the quantification of crystalline phases, textural relationships between minerals and chemical compositions of the phases covered by the combined results. Some key differences were found between QXRD and the microscopy techniques. QXRD results imply that not all of the silico-ferrite of calcium and aluminium (SFCA types) are being identified on the basis of morphology in the microscopy results. The amorphous concentration determined by QXRD was higher than the glass content identified in the microscopy results, whereas the magnetite and total SFCA concentration was lower. The scanning electron microscopy techniques were able to provide chemical analysis of the phases; however, exact correspondence with textural types was not always possible and future work is required in this area, particularly for differentiation of SFCA and SFCA-I phases. The results from the various techniques are compared and the relationships between the measurement results are discussed.

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Section: Quantitative X-ray Diffractionmentioning

confidence: 99%

Comparison of the Mineralogy of Iron Ore Sinters Using a Range of Techniques

et al. 2019

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“…The composition of SFCA varied in iron ore sinters [22]. The composition of SFCA contained 60-76 mass % Fe 2 O 3 , 3-10 mass % SiO 2 , 13-16 mass % CaO, 4-10 mass % Al 2 O 3 and 0.7-1.5 mass % MgO in industrial sinters [23,24].…”

Section: Sample Preparationmentioning

confidence: 99%

The Effects of Al2O3 and SiO2 on the Formation Process of Silico-Ferrite of Calcium and Aluminum (SFCA) by Solid-State Reactions

Liao

Guo

2019

Minerals

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The silico-ferrite of calcium and aluminum (SFCA) is a significant crystalline phase that bonds in high basicity sinter. Al2O3 and SiO2 play an important role in the formation of SFCA in the Fe2O3–CaO–SiO2–Al2O3 system, but the effect mechanism of Al2O3 and SiO2 on the formation of SFCA is unclear. To investigate this effect, sintering experiments were carried out with different temperatures and different times. It was found that the reaction of Al2O3 with CaFe2O4 (CF) as an initial product was easier to form during the calcium iron aluminum oxide (CFA) than that of SiO2 with CF to form SFC. This was due to the former directly forming to CFA while the latter initially formed Ca2SiO4 (C2S) and Ca2.5Fe15.5O25, and then SFC. It was also observed that when Al2O3 and SiO2 existed simultaneously, the Al2O3 initially reacted with CF to form CFA at 1100 °C, while the SiO2 participated in the formation of SFCA at 1150 °C without the formation of SFC. Moreover, it was understood that these were different effects in that the Al2O3 promoted the transformation from the orthorhombic crystal system to the triclinic crystal system, while the SiO2 dissolved into CFA to form the SFCA phase when Al2O3 existed.

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“…Phase quantification was done using the Rietveld method using the Autoquan program 14 . Crystal structure data of the crystalline phases and silicon standard were obtained from the ICSD crystal structure data base, with the exception of the SFCA structure, which was determined separately 15 . The crystal structure data are then used to calculate XRD patterns that are fitted to the experimental patterns.…”

Section: Xrd Analysismentioning

confidence: 99%

Variation of the redox conditions and the resultant phase assemblages during iron ore sintering

Berg

Villiers

Cromarty

2016

International Journal of Mineral Processing

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Highlights• The oxygen potential in a sinter bed is measured by a zirconia oxygen probe to be ~ 0.01 atm.• This oxygen potential in the sinter is appreciably more oxidizing than previous estimates.• The contents of a quenched sinter pot show that at the flame front, only magnetite and slag are present.• SFCA phases only form to a limited extent at the top of the quenched bed.• Thermodynamic modeling at a pO 2 of 0.01 atm is in qualitative agreement with the phase analysis of the sinter pot. AbstractThe oxygen potential prevailing during iron ore sintering was measured with a zirconia sensor in a series of sinter pot experiments. This was done to get a better indication of the redox conditions during commercial sintering. It was found that the pO 2 is appreciably more oxidizing than previously assumed, with a minimum value of ~0.01 atm. It is concluded that this value represents the oxygen potential of the gas phase and it is therefore a mixture of combustion gas and downdraft air. The contents of a quenched sinter pot where the reactions were interrupted with the flame front situated midway through the sinter bed were investigated. X-ray diffraction analysis, using an internal standard to quantify the amorphous slag phase, revealed that at the flame front only magnetite and slag was present. SFCA phases only formed at the top of the bed after the flame front had passed. Thermodynamic modeling of the phases at equilibrium agree qualitatively with the phase analysis and explained the extensive presence of magnetite and melt, as well as the formation of calcium ferrite phases during cooling below 1100°C.

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Refinement of iron ore sinter phases: a silico-ferrite of calcium and aluminium (SFCA) and an Al-free SFC, and the effect on phase quantification by X-ray diffraction

Cited by 25 publications

References 8 publications

Comparison of the Mineralogy of Iron Ore Sinters Using a Range of Techniques

Comparison of the Mineralogy of Iron Ore Sinters Using a Range of Techniques

The Effects of Al2O3 and SiO2 on the Formation Process of Silico-Ferrite of Calcium and Aluminum (SFCA) by Solid-State Reactions

Variation of the redox conditions and the resultant phase assemblages during iron ore sintering

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