The Structure and Properties of Silicate Slags

Mills, Kenneth C.; Hayashi, Miyuki; Wang, Lijun; Watanabe, Takashi

doi:10.1016/b978-0-08-096986-2.00008-4

Cited by 40 publications

(28 citation statements)

References 158 publications

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“…Generally, cations with 6-fold coordination (in octahedral array) are more likely to act as network breakers (or network modifiers) compared to 4-or 5-fold coordinated ones in silicate systems. 4) Therefore, the variation in the coordination of Fe 2 + may imply that the network-modifying effect of Fe 2 + on the Si-O network is enhanced by the addition of V 2 O 3 . The existing structural positions of Fe 2 + in our simulations are in accordance with previous studies, 15,16,18,[21][22][23][24][25][26] in spite of the investigated silicate systems may vary from one to the other.…”

Section: Local Structure Of the Meltsmentioning

confidence: 99%

“…[14][15][16]18,[21][22][23][24][25] Notwithstanding, in most cases FeO acts as a network modifier which offers O 2 − and thus depolymerizes the silicate network. 4,15) Although there are numerous studies on the structural characterization and physicochemical properties of V-containing materials, rather limited information is available on the structural configurations of trivalent V in silicate melts and glasses. To the authors' knowledge, only Keppler 22) reported that V 3 + occupies octahedral coordination in glasses along the diopside-albite join by using optical spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

“…2) In this process, V-containing hot metal will be oxidized in a LD converter to produce vanadium slag, which is an important intermediate product of vanadium extraction from V-Ti magnetite. Investigating the structure of molten slag is of great help for understanding and controlling the properties of slag such as viscous flow, 3,4) which is also a significant thermophysical property for vanadium slag since it will influence the slag-metal separation as well as oxidation of vanadium from the hot metal into the slag. 2,5) Fe and V are both transition elements that can exist in variable oxidation states and structural environments under different internal or external conditions.…”

Section: Introductionmentioning

confidence: 99%

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Structural Characterization of FeO–SiO2–V2O3 Slags Using Molecular Dynamics Simulations and FT-IR Spectroscopy

et al. 2016

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The structure of FeO-SiO 2 -V 2 O 3 slags with compositions of (1-x)(1.5FeO·SiO 2 )·xV 2 O 3 (x = 0-20% mole fraction) was investigated in the molten and quenched states by using molecular dynamics (MD) simulations and Fourier transform infrared (FT-IR) spectroscopy. An empirical potential for the multi-component system has been developed in this work for performing MD simulations. The local atomic structures and the micro-heterogeneity in the molten slag have been systematically investigated using MD simulations. The bond length of V-O varies from 1.92 to 1.96 Å and the averaged coordination number of V (CN V-O ) increases from 4.50 to 4.96 with the addition of V 2 O 3 . The simulation results revealed that the average Si-O-Si bond angle and the degree of polymerization both decrease with increasing amount of V 2 O 3 , implying that V 2 O 3 may behave as a network-modifying basic oxide in the FeO-SiO 2 -V 2 O 3 system. This was further confirmed by the FT-IR spectrum analysis, which shows that the silicate network dissociates with the presence of V 2 O 3 .

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Section: Local Structure Of the Meltsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural Characterization of FeO–SiO2–V2O3 Slags Using Molecular Dynamics Simulations and FT-IR Spectroscopy

et al. 2016

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“…The rheological properties of mold flux are affected by its microstructure; and, DOP is a vital parameter to determine the melt structure, which is directly related to the viscosity of mold flux. In general, the methods of Q 3 (Si)/Q 2 (Si) ratio and NBO/T ratio (defined as the ratio of the mole fraction of available network breaking oxides to the mole fraction of tetrahedral‐coordinated cations) from Equation and Q from Equation are used to characterize the DOP of melt structure.

\frac{NBO}{T} = \frac{2 (\sum X_{M_{2} O} + \sum X_{MO} - X_{{Al}_{2} O_{3}})}{X_{{SiO}_{2}} + 2 X_{{Al}_{2} O_{3}}}

Q = 4 - \frac{NBO}{T}

where X is the mole fraction of each component,

\sum X_{M_{2} O} = X_{{Li}_{2} O} + X_{{Na}_{2} O} + X_{K_{2} O} + …,

and

\sum X_{MO} = X_{CaO} + X_{MgO} + \dots

…”

Section: Discussionmentioning

confidence: 99%

The evolution of the mold flux melt structure during the process of fluorine replacement by B₂O₃

et al. 2019

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This study presented the melt structure evolution of mold flux during the substitution of fluorine by B2O3, and a computational model for the degree of polymerization (DOP) for borosilicate structure was developed. The results showed that the reduction of fluorine content would promote the replacement of F in [SiF6]‐octahedral unit by the dissociative free oxygen ions (O2−), and release F− ions into the melt to compensate the reduction of F− ions. With the 2 mass% addition of B2O3, the original Si–O–Si bond would be disrupted, and connect with [BO3]‐trihedral to form boroxol ring structure containing [BO2O−]‐trihedral and [BO3]‐trihedral structural units. Then, the Si–O–B bond that [BO3]‐trihedral links [SiO4]‐tetrahedral in boroxol ring was destroyed with the further addition of B2O3, and then the [BO3]‐trihedral could link with the dissociative Q1(Si) and Q0(Si) structural units to transform into [BO4]‐tetrahedral and form a borosilicate long chain. Finally, with 6 mass% addition of B2O3, the borosilicate chain would combine with simple borate and borosilicate structures, and a complex borosilicate structure containing boroxol ring with certain symmetry was formed ultimately. Besides, the calculated result of DOP suggested that the DOP of the melt structure improved during the process of fluorine replacement by B2O3.

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“…However, researchers also hold the view that Fe 3+ can act as both a network former and a network modifier. 13 Experiments show that fourfold coordinated Fe 3+ is more common, but higher coordination such as fivefold and sixfold is also possible. 14,15 This divergence is also reported in viscosity.…”

Section: Introductionmentioning

confidence: 99%

Different Roles of Iron Species in the Network Structure and Viscosity of Silicate Melts

Wang

Guhl

et al. 2020

Energy Fuels

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In iron-containing silicate melts such as gasification slags and geological slags, iron can play a different role in the melt properties because of its varying valence states. In this paper, the structural characteristics and viscosities of five samples were studied by molecular dynamics simulation and thermodynamic calculation methods. The effect of different iron species on the structure and properties is revealed. More than half of the Fe 3+ ions are in four-coordination. The four-and fivefold coordinated ferric ions are in dynamic equilibrium. The four-coordinated Fe 3+ can connect with the other tetrahedrons centered by Si 4+ and Al 3+ or integrate into three-coordinated oxygen units. With an increase of the iron content, the polymerization degree characterized by nonbridged oxygen per tetrahedra (NBO/T) is found to be inconsistent with the trend of viscosity. Based on the energy of the different types of oxygen, a new parameter RS total is proposed to substitute the original NBO/T and correlate with viscosity in an exponential function. Liquid iron can form in molten slags under a strong reducing atmosphere, which can inhibit the diffusion of oxygen and increase the viscosity.

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The Structure and Properties of Silicate Slags

Cited by 40 publications

References 158 publications

Structural Characterization of FeO–SiO<sub>2</sub>–V<sub>2</sub>O<sub>3</sub> Slags Using Molecular Dynamics Simulations and FT-IR Spectroscopy

Structural Characterization of FeO–SiO<sub>2</sub>–V<sub>2</sub>O<sub>3</sub> Slags Using Molecular Dynamics Simulations and FT-IR Spectroscopy

The evolution of the mold flux melt structure during the process of fluorine replacement by B₂O₃

Different Roles of Iron Species in the Network Structure and Viscosity of Silicate Melts

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The Structure and Properties of Silicate Slags

Cited by 40 publications

References 158 publications

Structural Characterization of FeO–SiO<sub>2</sub>–V<sub>2</sub>O<sub>3</sub> Slags Using Molecular Dynamics Simulations and FT-IR Spectroscopy

Structural Characterization of FeO–SiO<sub>2</sub>–V<sub>2</sub>O<sub>3</sub> Slags Using Molecular Dynamics Simulations and FT-IR Spectroscopy

The evolution of the mold flux melt structure during the process of fluorine replacement by B2O3

Different Roles of Iron Species in the Network Structure and Viscosity of Silicate Melts

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The evolution of the mold flux melt structure during the process of fluorine replacement by B₂O₃