Viscosity Measurement of Calcium Ferrite Based Slags during Structural Relaxation Process

Sukenaga, Sohei; Gonda, Yoshiaki; Yoshimura, S.; Saito, Noritaka; Nakashima, Kouichi

doi:10.2355/isijinternational.50.195

Cited by 19 publications

(10 citation statements)

References 13 publications

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“…It should be noted that the viscosity of the NSF melt decreased with melting time even under air. In a previous paper, 25) similar phenomena were observed in the CaO-SiO2-FexO system. In that paper, we clarified that this phenomenon was due to an increase in the amount of octacoordinated Fe 3+ ions (Fe 3+ (6)) that behave as network modifiers.…”

Section: Analysis Of the Oxidation States Of Iron Ions In The Samplessupporting

confidence: 78%

Effect of Oxidation State of Iron Ions on the Viscosity of Alkali Silicate Melts

et al. 2013

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Understanding the changes in viscosity due to the different oxidation states of iron ions is important for simulating phenomena related to molten slags and also for understanding the structure of iron-oxidecontaining silicate melts. However, these viscosity changes are not well understood. Here, we show the viscosity changes of R2O-SiO2-FexO (R = Li, Na, or K) melts due to changes in the oxidation states of the iron ions by systematically varying the oxygen partial pressure using several Ar-based gases at 1 773 K. The initial compositions of the samples were 30R2O-60SiO2-10Fe2O3 (mol%), and the ratio of Fe 3+ to Fe 2+ in the R2O-SiO2-FexO melts increased with increasing oxygen partial pressure in all samples. Meanwhile, the viscosity of all the R2O-SiO2-FexO melts decreased with increasing Fe 2+ to total-Fe ratio. The data indicate that the increase in the amount of Fe 2+ ions, which behave as network modifiers, would result in depolymerization of the silicate melts. It should also be noted that the viscosity of the melts increased in the order of alkali cationic radius (K > Na > Li) when the ratios of Fe 2+ to Fe 3+ in the melts were comparable. This was due to the change in the coordination structure of Fe 3+ in the melts. Not only the oxidation state of the iron ions but also the coordination structure of Fe 3+ may be important for understanding the viscosity.KEY WORDS: viscosity; alkali ferrosilicate melts; redox equilibria of Fe; oxygen partial pressure.

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Section: Analysis Of the Oxidation States Of Iron Ions In The Samplessupporting

confidence: 78%

Effect of Oxidation State of Iron Ions on the Viscosity of Alkali Silicate Melts

et al. 2013

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“…The viscous behaviour of ironmaking slags plays an essential role in view of the productivity and quality of hot metal by affecting the gas permeability and refining ability. In this respect, much work has been attempted to understand the viscosity of slag through various models (Riboud et al 1, Urbain 2, Kondratiev et al 3, Iida et al 4, Nakamoto et al 5), thermodynamic properties (excess Gibbs energy of mixing 6, activity coefficient 7), structural investigation 8 and experimental verification for ironmaking slags 9–12.…”

Section: Introductionmentioning

confidence: 99%

A Study on the Viscous Behaviour with K₂O Additions in the CaOSiO₂Al₂O₃MgOK₂O Quinary Slag System

Kim

Sohn

Min

2010

steel research int.

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The viscosities of CaOSiO220wt%Al2O310 wt%MgO‐K2O quinary slags with CaO/SiO2 from 0.8 to 1.2 at 1773 K with 1–5 wt% K2O additions were measured to estimate the effect of K2O on the viscous behaviour of the slags. The measured viscosity at 1773 K increased with K2O addition at a fixed CaO/SiO2, which is contrary to the effect of Na2O on the viscosity of BF slags. To qualitatively verify the changes in slag structure, FT‐IR spectroscopy was used. It was found that K2O induces Al2O3 to behave as an acidic oxide by forming [AlO4]5−‐tetrahedral units by the ionic compensation effect of K+ cations. However, regarding the effect of K2O on the silicate structure, it is observed that K2O has a negligible effect due to the consumption of O2− with the formation of [AlO4]5−‐tetrahedral units. Furthermore, it is also found that SiOAl bending became more complicated with K2O additions, which supports the selective effect of K2O on the aluminate structure of the slag. In spite of the more complicated structure with K2O additions, the critical temperature (TCR) decreased due to the gradual reduction of the liquidus temperature (TLQ) of the slags.

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“…Furthermore, increasing content of Al 2 O 3 also increased the melting temperature of SFCA and, thus, the heat demand for primary melt formation [36]. At the same time, the high-alumina content in iron ore sinters is associated with high viscosity of the melt [41,42]. This is more significant than the SiO 2 influence because of the calcium ferrite-based melt formation process.…”

Section: High-alumina Iron Ore Sintermentioning

confidence: 97%

Ore Assimilation and Secondary Phases by Sintering of Rich and High-Gangue Iron Ores

et al. 2019

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During the iron ore sintering process, two types of particles are present in the sinter bed: (1) fines, which are actively taking part in melting and the formation of secondary phases, and (2) coarse ores, which are partially interacting with the surrounding melt. The quality of the final sinter is particularly determined by the secondary phases and their bonding ability. Due to chemical differences between the fines and coarse particles, knowing the overall chemical composition of the sintering blend is not sufficient to estimate the final sinter microstructure. In this study, different ore types were used to prepare iron-rich, high-alumina, and high-silica blends, which were sintered in a laboratory sinter pot to investigate the behavior of fine as well as coarse particles. As a result, very different sinter matrices formed depending on the useful basicity in each sinter. The density, mineral nature, and the gangue of the ore affected coarse ore assimilation.

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Viscosity Measurement of Calcium Ferrite Based Slags during Structural Relaxation Process

Cited by 19 publications

References 13 publications

Effect of Oxidation State of Iron Ions on the Viscosity of Alkali Silicate Melts

Effect of Oxidation State of Iron Ions on the Viscosity of Alkali Silicate Melts

A Study on the Viscous Behaviour with K₂O Additions in the CaOSiO₂Al₂O₃MgOK₂O Quinary Slag System

Ore Assimilation and Secondary Phases by Sintering of Rich and High-Gangue Iron Ores

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Viscosity Measurement of Calcium Ferrite Based Slags during Structural Relaxation Process

Cited by 19 publications

References 13 publications

Effect of Oxidation State of Iron Ions on the Viscosity of Alkali Silicate Melts

Effect of Oxidation State of Iron Ions on the Viscosity of Alkali Silicate Melts

A Study on the Viscous Behaviour with K2O Additions in the CaOSiO2Al2O3MgOK2O Quinary Slag System

Ore Assimilation and Secondary Phases by Sintering of Rich and High-Gangue Iron Ores

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A Study on the Viscous Behaviour with K₂O Additions in the CaOSiO₂Al₂O₃MgOK₂O Quinary Slag System