Abstract:The thermodynamics, structural and transport properties (density, melting point, heat capacity, thermal expansion coefficient, viscosity and electrical conductivity) of a ferro-aluminosilicate slag have been studied in the solid and liquid state (1273–2273 K) using molecular dynamics. The simulations were based on a Buckingham-type potential, which was extended here, to account for the presence of Cr and Cu. The potential was optimized by fitting pair distribution function partials to values determined by Reve… Show more
“…We note that melting is favoured by increasing electric potential and slag electrical conductivity. These findings are potentially important to the fine tuning of the industrial EAF operation as modifying the Si, Al and Fe slag content, among others, may severely impact its electrical conductivity [ 8 ]. Figure 7.…”
Section: Resultsmentioning
confidence: 99%
“…The density and viscosity of the slag layer as well as the electrical conductivity of the ferronickel layer were specified as piecewise linear functions of temperature in order to incorporate temperature variability into the models. Moreover, due to the uncertainty involved in the determination of the electrical and thermal conductivity of the slag, trial ranges between 0.5 and 10.0 S m −1 and 3.0–7.0 W m −1 K −1 were used, respectively [ 8 ]. Also, slag viscosity in the range 0.002–0.2 kg m −1 s −1 was deemed adequate for the study of the influence of the Lorentz force on melt velocities.…”
A transient mathematical model was developed for the description of fluid flow, heat transfer and electromagnetic phenomena involved in the production of ferronickel in electric arc furnaces. The key operating variables considered were the thermal and electrical conductivity of the slag and the shape, immersion depth and applied electric potential of the electrodes. It was established that the principal stimuli of the velocities in the slag bath were the electric potential and immersion depth of the electrodes and the thermal and electrical conductivities of the slag. Additionally, it was determined that, under the set of operating conditions examined, the maximum slag temperature ranged between 1756 and 1825 K, which is in accordance with industrial measurements. Moreover, it was affirmed that contributions to slag stirring due to Lorentz forces and momentum forces due to the release of carbon monoxide bubbles from the electrode surface were negligible.
“…We note that melting is favoured by increasing electric potential and slag electrical conductivity. These findings are potentially important to the fine tuning of the industrial EAF operation as modifying the Si, Al and Fe slag content, among others, may severely impact its electrical conductivity [ 8 ]. Figure 7.…”
Section: Resultsmentioning
confidence: 99%
“…The density and viscosity of the slag layer as well as the electrical conductivity of the ferronickel layer were specified as piecewise linear functions of temperature in order to incorporate temperature variability into the models. Moreover, due to the uncertainty involved in the determination of the electrical and thermal conductivity of the slag, trial ranges between 0.5 and 10.0 S m −1 and 3.0–7.0 W m −1 K −1 were used, respectively [ 8 ]. Also, slag viscosity in the range 0.002–0.2 kg m −1 s −1 was deemed adequate for the study of the influence of the Lorentz force on melt velocities.…”
A transient mathematical model was developed for the description of fluid flow, heat transfer and electromagnetic phenomena involved in the production of ferronickel in electric arc furnaces. The key operating variables considered were the thermal and electrical conductivity of the slag and the shape, immersion depth and applied electric potential of the electrodes. It was established that the principal stimuli of the velocities in the slag bath were the electric potential and immersion depth of the electrodes and the thermal and electrical conductivities of the slag. Additionally, it was determined that, under the set of operating conditions examined, the maximum slag temperature ranged between 1756 and 1825 K, which is in accordance with industrial measurements. Moreover, it was affirmed that contributions to slag stirring due to Lorentz forces and momentum forces due to the release of carbon monoxide bubbles from the electrode surface were negligible.
“…5 Å), 43,48 suggesting a similarity in topological ordering, specifically 2D rings of SiO 4 tetrahedra in the vitreous silica 43,49 and therefore Si/Fe rings in the slags. A more detailed description of the ring sizes in silicate glasses needs a computational approach, 49 as reported by Karalis et al 28 for a similar Fe-silicate slag.…”
Section: Cao-feo X -Sio 2 Slagsmentioning
confidence: 99%
“…Pair distribution function analysis has also been intensively used to investigate short and intermediate range ordering in silicate glasses, often in combination with theoretical modeling. The coordination number can be calculated from the area underneath the M–O partial PDF (for the amount of oxygen surrounding M) taking into account the molar fraction of this element and scattering length of the neutrons/X‐rays . Furthermore, information on the coordination state(s) of Fe in Fe‐silicate slag and related systems can be obtained from the position of the Fe–O correlation .…”
Section: Introductionmentioning
confidence: 99%
“…The coordination number can be calculated from the area underneath the M-O partial PDF (for the amount of oxygen surrounding M) taking into account the molar fraction of this element and scattering length of the neutrons/X-rays. [25][26][27][28] Furthermore, information on the coordination state(s) of Fe in Fe-silicate slag and related systems can be obtained from the position of the Fe-O correlation. [29][30][31] Interestingly, although 5-fold coordinated iron is rarely found in minerals, it is quite often observed in glasses.…”
The molecular structures of CaO–FeOx–SiO2 slags and their inorganic polymer counterparts were determined using neutron and X‐ray scattering with subsequent pair distribution function (PDF) analysis. The slags were synthesized with approximate molar compositions: 0.17CaO–0.83FeO–SiO2 and 0.33CaO–0.67FeO–SiO2 (referred to as low‐Ca and high‐Ca, respectively). The PDF data on the slags reasserted the predominantly glassy nature of this iron‐rich industrial byproduct. The dominant metal‐metal correlation was Fe–Si (3.20‐3.25 Å), with smaller contributions from Fe–Ca (3.45‐3.50 Å) and Fe–Fe (2.95‐3.00 Å). After inorganic polymer synthesis, a rise in the amount of Fe3+ was observed via the shift of the Fe–O bond length to shorter distances. This shortening of the Fe–O distance in the binder is also evidenced by the apparent rise of the Fe–Fe correlation at 2.95‐3.00 Å, although this feature may also suggest a potential aggregation of FeOx clusters. In general, the atomic arrangements of the reaction product was shown to be very similar to the precursor structure and the dominance of the Fe–Si correlation suggests the participation of Fe in the silicate network. The binder was shown to be glassy, as no distinct atom‐atom correlations were observed beyond 8 Å.
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