Effects of Gibbsite, Kaolinite and Al-rich Goethite as Alumina Sources on Silico-Ferrite of Calcium and Aluminium (SFCA) and SFCA-I Iron Ore Sinter Bonding Phase Formation

Webster, Nathan A. S.; O’Dea, Damien; Ellis, Ben G.; Pownceby, Mark I.

doi:10.2355/isijinternational.isijint-2016-332

Cited by 44 publications

(30 citation statements)

References 38 publications

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“…A number of recent investigations 9,[11][12][13][14][15][16][17][18][19] have utilised in situ XRD in order to establish the formation mechanisms of SFCA phases under simulated sintering conditions from synthetic starting sinter mixtures in the range 298-1 623 K, under oxygen partial pressures (pO 2 ) in the range 0.21 to 1 × 10 − 4 atm, and at basicity (B, = CaO:SiO 2 ) values in the range 2.5-5. Regarding basicity, Webster at al.…”

Section: Introductionmentioning

confidence: 99%

“…The base mixture, SM4/5, with B = 4.0 and containing 5 wt% Al 2 O 3 has been utilised in a number of our previous investigations. 9,[13][14][15][16][17][18][19] The SM3/5 and SM2.5/5 mixtures, with B = 3.0 and 2.5, respectively, were designed to examine the effect of basicity. The SM4/5-1MgO and 3MgO mixtures, with 1 and 3 wt% addition of MgO to SM4/5, respectively, were designed to examine the effect of Mg concentration.…”

Section: Introductionmentioning

confidence: 99%

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Fundamentals of Silico-Ferrite of Calcium and Aluminium (SFCA) Iron Ore Sinter Bonding Phase Formation: Effects of Basicity and Magnesium on Crystallisation during Cooling

et al. 2019

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The effects of basicity and Mg addition on the crystallisation during cooling of complex Ca-rich ferrite iron ore sinter bonding phases SFCA and Fe-rich SFCA was investigated using in situ synchrotron X-ray diffraction. In synthetic iron ore sinter mixtures, cooling of a high temperature (T = 1 623 K) assemblage comprising magnetite and melt showed that decreasing basicity from B = 4.0 to 3.0 and 2.5 resulted in the formation of a Fe-rich SFCA phase being suppressed, with SFCA being the only Ca-rich ferrite phase to form initially from the melt at B = 2.5. Increasing the Mg concentration in the sinter mixtures to 1 and 3 wt% MgO resulted in an overall suppression of the amount of Ca-rich ferrite phase formation. However, Mg addition caused the formation of Fe-rich SFCA to be favoured over SFCA, with SFCA not observed to form at all during cooling in the 3 wt% MgO mixture. The absence of SFCA in the high-Mg experiment was rationalised on the basis that the Fe-rich SFCA structure accommodates more Fe 2 + than the SFCA structure, thereby stabilising Fe-rich SFCA relative to SFCA through replacement substitution of Fe 2 + by Mg 2 + . Observation of Fe-rich SFCA in sinter may be an indicator of localised high basicity, and/or, high Mg concentration, within a sinter blend.KEY WORDS: iron ore sinter; in situ synchrotron X-ray diffraction; complex Ca-rich ferrite iron ore sinter bonding phases; SFCA; crystallisation during cooling; CaO:SiO 2 ratio; Mg addition.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fundamentals of Silico-Ferrite of Calcium and Aluminium (SFCA) Iron Ore Sinter Bonding Phase Formation: Effects of Basicity and Magnesium on Crystallisation during Cooling

et al. 2019

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“…Due to slow diffusion of alumina in the solid state, the contribution of alumina from the crucible was negligible. As a consequence, binary and ternary calcium ferrites were formed, which served as the precursor phases for SFCA formation with chemical compositions probably close to the composition of the starting-mixtures [40]. When the peak temperatures (1450 and 1500 • C) were reached, incongruent melting occurred.…”

Section: Chemical Composition Of Sfcamentioning

confidence: 99%

Synthesis and Mechanical Testing of Calcium Aluminosilicoferrite Crystals with High Alumina Content

Mežibrický

Csanádi

Habler

et al. 2019

Metals

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Due to the gradual shift to less rich iron ores, the alumina content in the raw materials used for iron-making is progressively increasing, affecting the mineralogy and the properties of iron ore sinters. In this context, the effect of Al content on the mechanical properties of calcium aluminosilicoferrites Ca2(Ca,Mg,Fe)6(Fe,Si,Al)6O20 (SFCA), which is the most important bonding phase in iron ore sinters, is of particular interest. In this study, high-alumina calcium aluminosilicoferrites were synthesized and their mechanical properties were determined by nanoindentation using a cube-corner indenter. For synthesis, different raw materials were taken as proxies for the adhering layer in a sinter granule. Three mixtures were prepared, high-iron, high-silica, and high-alumina and heated in an alumina crucible, which was used to simulate the high-alumina nucleus in a granule. The different raw materials used for synthesis had only minor influence on the compositions of the synthesized ferrites. All ferrites showed similar mechanical behavior during indentation, indicating that neither the chemical nor the mechanical properties were affected by the different compositions of the adhering layer, when the sinter granule is dominated by a high-alumina nucleus. The crystallographic orientation of the tested grains had only minor influence on the results of the nanoindentation experiments.

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“…Still, their influence has not been clearly revealed, and some points were even found to be contradictory. It has been widely regarded that a content of Al 2 O 3 exceeding 2.5% will deteriorate the sinter quality, while the influence of an Al 2 O 3 content ≤2.5% on sinter quality 2 of 14 has not been clearly elucidated [7][8][9][10]. The research regarding the influence of SiO 2 content on sinter quality has mainly been conducted by changing the content of CaO in sinter as well, so it is difficult to reveal how only the content of SiO 2 affects the sintering performance [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Minerals Evolution of Iron Ore Sinter: Influence of SiO2 and Al2O3

Zhao

Gan

et al. 2019

Minerals

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SiO2 and Al2O3 are two important minerals that can affect the mechanical and metallurgical properties of sinter. This investigation systematically studied the influences of these minerals and revealed their functional mechanisms on sinter quality. Results showed that with an increasing Al2O3 content in sinter, the sintering indexes presented an improvement before the content exceeded 1.80%, while the quality decreased obviously after the content exceeded 1.80%. With an increasing SiO2 content, the sinter quality presented a decreasing tendency, especially when the content exceeded 4.80%. Consequently, the optimal content of Al2O3 was ≤1.80% and that of SiO2 was ≤4.80%. The evolution of the microstructure and minerals in sinter showed that enhancing the Al2O3 content increased the proportion of SFCA generated, which improved the sinter’s mechanical strength, while excessive Al2O3 led to the formation of sheet-like SFCA with weak mechanical strength. Increasing the content of SiO2 strained the formation of SFCA and promoted the formation of calcium silicate, the mechanical strength of which is lower than that of SFCA. The research findings will be useful in guiding practical sintering processes.

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Effects of Gibbsite, Kaolinite and Al-rich Goethite as Alumina Sources on Silico-Ferrite of Calcium and Aluminium (SFCA) and SFCA-I Iron Ore Sinter Bonding Phase Formation

Cited by 44 publications

References 38 publications

Fundamentals of Silico-Ferrite of Calcium and Aluminium (SFCA) Iron Ore Sinter Bonding Phase Formation: Effects of Basicity and Magnesium on Crystallisation during Cooling

Fundamentals of Silico-Ferrite of Calcium and Aluminium (SFCA) Iron Ore Sinter Bonding Phase Formation: Effects of Basicity and Magnesium on Crystallisation during Cooling

Synthesis and Mechanical Testing of Calcium Aluminosilicoferrite Crystals with High Alumina Content

Microstructure and Minerals Evolution of Iron Ore Sinter: Influence of SiO2 and Al2O3

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