Pragmatic analysis of the electric submerged arc furnace continuum

Abstract

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.

Three-dimensional Computational Fluid Dynamics Analysis of an Electric Submerged Arc Furnace

“…By solving the equations ( 12)-( 15) the values and the corresponding gradients of temperature and velocity were calculated in the developed three dimensional discretized domain. The temperature gradients in the EAF are a direct outcome of Joule heating 21 which, in turn, is proportional to the current density, j, relating the flow of electric current, q according to equation ( 14) 7,8 . To calculate j, the aggregate FeNi/slag σ value can be inputted into Eq.5, then solving the system of Eq.5 and 10 in order to obtain the spatial distribution of the electric potential V, on the provisions that B is zero as there is no magnetic field external to the EAF rig, B0 is by definition zero (Eq.6) and b is negligible as previously shown by us 8 .…”

“…where B0 and b represent the contributions from the external and induced magnetic field, respectively; in the current model, B0 is by definition zero and we have previously shown b to be infinitesimal 7,8 and may, thus, be ignored. We note that Eq.4 is valid under the additional provision that charge mobility is sufficiently low.…”

“…EAFs typically operate at temperatures as high as 2000 K 6 under the effect of Joule heating maintained by a number of self-backing Söderberg electrodes 7 which are continuously consumed via submersion into a slag melt 1,7 . FeNi recovery is, then, achieved by continuous chemical reduction promoted by high-temperature (fast) metal/slag reaction kinetics, enhanced mass and heat transfer, electromagnetic stirring of the slag bath owing to buoyancy effects 7,8 and low slag viscosity 9 . Intrinsically, however, metal recovery is dependent on the slag's electrical conductivity (EC) and its effect on transport properties of the mesoscale [10][11][12] ; slag EC itself is very sensitive to even fractional changes in the chemical concentration of the ore, which reflect on final nickel quality.…”

Direct determination of amorphous number density from the reduced Pair Distribution Function

“…However, upon increasing deviation from bulk crystallinity, this baseline becomes affected by the dominating presence of an attenuating particle shape factor, g(r), and is, then, expressed as À4pr 0 g(r)r [1]. The extreme case of linearity deviation towards high values of the real space coordinate, r, is that of completely amorphous materials [2][3][4][5][6][7], in which case r 0 may not be estimated from the tangent of the baseline as the latter is no longer a straight line [8]. In some cases, numerical estimation (i.e.…”

Direct determination of amorphous number density from the reduced pair distribution function

“…However, upon increasing deviation from bulk crystallinity, this baseline becomes affected by the dominating presence of an attenuating particle shape factor, γ(r), and is, then, expressed as −4πρ 0 γ(r)r [1]. The extreme case of linearity deviation towards high values of the real space coordinate, r, is that of completely amorphous materials [[2], [3], [4], [5], [6], [7]], in which case ρ 0 may not be estimated from the tangent of the baseline as the latter is no longer a straight line [8]. In some cases, numerical estimation (i.e.…”