The Composition of CaO-FeO-Fe2O3 and MnO-FeO-Fe2O3 Melts at Several Oxygen Pressures in the Vicinity of 1600°

Gurry, R. W.; Darken, L. S.

doi:10.1021/ja01165a021

Cited by 33 publications

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“…This means that ≈1.2% of the iron ions are reduced to Fe 2+ . This is significantly less than that measured by Gurry and Darken (≈5%, [34]). However, they performed the following:…”

Section: Calcium Ferritecontrasting

confidence: 59%

“…[10,33]) it is obvious that the liquid FeO x "slag" phase always contains both valence states of iron, and their ratio depends on T and p O 2 . Gurry and Darken [34] measured in a CaO/FeO x melt with 36.6 mol-% CaO that was held for 1 h at 1574 °C a Fe 3+ /Fe 2+ ratio of ≈19. Recently, Bykova et al [35] showed that even under very high temperatures, T 2000 K and pressures p > 50 GPa Fe 2 O 3 does not melt stoichiometrically; rather, mixed valence oxides of a series nFeO•mFe 2 O 3 were found.…”

Section: Experiments and Resultsmentioning

confidence: 99%

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On Thermodynamic Aspects of Oxide Crystal Growth

Klimm

Wolff

2022

Applied Sciences

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Several metal oxide compounds, especially those containing metals possessing several valence states, are able to absorb or release oxygen under suitable thermodynamic conditions. Such behavior is found often in systems containing oxides of transition metals. It is important to note that the equilibrium oxidation level of those metal oxides can depend on the aggregation state, which may significantly impede crystal growth processes from the melt. If during the melt growth of such oxide crystals, the average valence state of the oxides is different in the molten and solid state, then crystallization is connected with the absorption of free oxygen from the ambient gas, or with the release of free oxygen into it. This phenomenon can be detected by simultaneous DTA/TG measurements and can deteriorate the stability of crystal growth. This holds especially if the average valence in the solid is smaller than in the melt, because oxygen release can lead to bubble formation at the crystallization front.

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“…This means that ≈1.2% of the iron ions are reduced to Fe 2+ . This is significantly less than that measured by Gurry and Darken (≈5%, [34]). However, they performed the following:…”

Section: Calcium Ferritecontrasting

confidence: 59%

Section: Experiments and Resultsmentioning

confidence: 99%

On Thermodynamic Aspects of Oxide Crystal Growth

Klimm

Wolff

2022

Applied Sciences

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“…The and acts as a coating against hydration. [4][5][6][7][8][9][10][11][12][13][14][15][16] Some In case of In 1988, Bergman and Song [8] studied the Ca-Fe-O system slowly cooled slag, the FeO seems to be homogeneously and concluded that the system is not eutectic, supporting distributed in the free-CaO phase, and the hydration of the the phase diagram suggested by Abbatista et al [5] On this free CaO becomes easier.…”

Section: Introductionmentioning

confidence: 99%

Solid-state reaction kinetics of the system CaO-FeO

Fukuyama

Hossain

Nagata

2002

Metall Mater Trans B

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The solid-state reaction mechanisms of the CaO-FeO system have been studied by a diffusion couple method in the temperature range of 1073 to 1273 K, under controlled oxygen-partial pressures. The interdiffusivities and intrinsic diffusivities of Ca 2+ and Fe 2+ have been determined in the limited FeO solid-solution range. Based on the obtained results, a solid-state reaction model of the system has been developed, taking account of the formation of the Ca 2 Fe 2 O 5 phase. According to the model, the diffusivities of Fe 3+ in the Ca 2 Fe 2 O 5 phase have been estimated at 1273 K.

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“…The advantages of calcium ferrite slags over the more conventional iron silicate slags include A lower dissolved copper content at a given activity of copper in slag, [11,12] A higher capacity to dissolve ferric iron and, hence, magnetite, and [13] A higher capacity for some acidic minor elements such as arsenic and antimony. [14,15] Most of the thermodynamic investigations into calcium ferrite slags have concentrated on liquidus boundaries at copper-making temperatures, [10,[16][17][18][19][20] iron redox equilibria, [16][17][18][21][22][23][24] and the solubility of copper in slag. [11,15,19,25,26] Nikolic et al [27] and Hidayat et al [28] investigated the thermodynamics of complex slag systems relevant to modern copper smelting and converting processes as part of a thermodynamic modeling study.…”

Section: Michael Somerville Shouyi Sun and Sharif Jahanshahimentioning

confidence: 99%

Copper Solubility and Redox Equilibria in Magnesia Saturated CaO-CuOx-FeOx Slags

Somerville

Sun

Jahanshahi

2014

Metall Mater Trans B

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New measurements on solubility of copper and redox equilibria in magnesia-saturated calcium ferrite-based slags are presented. These data were obtained from equilibrium experiments at 1573 K (1300°C) and over a range of oxygen partial pressures of 10 À11 to 10 À5 atm, through equilibrating the slag with metallic copper in magnesia crucibles under a flowing Ar-CO-CO 2 gas mixture. At low oxygen partial pressures, copper was found to dissolve into slag as a univalent species (CuO 0.5 ) with a linear dependence on the oxygen partial pressure (in logarithm), with a slope of 0.23. At higher oxygen partial pressures (>10 À7 atm), the data suggest a divalent copper species becomes significant (CuO) and causes the dependence on oxygen partial pressure to increase. The determination of the Fe 3+ /Fe 2+ ratio in the slag was effected by the cuprous (Cu + ) content, which acts to increase the apparent ferrous (Fe 2+ ) content during acid digestion. A correction procedure was applied to the Fe 3+ /Fe 2+ ratio based on the calculated Cu + content of the slag. The procedure assumes that the activity coefficients of CuO 0.5 and CuO (c CuO 0:5 and c CuO ) in these slags are independent of oxygen partial pressure. The calculated activity coefficients of CuO 0.5 and CuO were 3.43 and 0.29, respectively. The corrected Fe 3+ / Fe 2+ ratio had a linear dependence of 0.17 on the oxygen partial pressure over the entire oxygen partial pressure range. This agrees with similar data from the literature.

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The Composition of CaO-FeO-Fe₂O₃ and MnO-FeO-Fe₂O₃ Melts at Several Oxygen Pressures in the Vicinity of 1600°

Cited by 33 publications

References 0 publications

On Thermodynamic Aspects of Oxide Crystal Growth

On Thermodynamic Aspects of Oxide Crystal Growth

Solid-state reaction kinetics of the system CaO-FeO

Copper Solubility and Redox Equilibria in Magnesia Saturated CaO-CuOx-FeOx Slags

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