Numerical modelling of fluid flow and desulphurisation kinetics in an argon-stirred ladle furnace

Abstract

A full-scale, three-dimensional, transient CFD modelling approach capable of predicting the threephase fluid-flow characteristics and desulphurisation behaviour in an argon-stirred ladle was developed. The model can accurately predict the molten steel flow and slag eye behaviour. The predicted sulphur content in ladle as a function of time agrees well with the experimental data. The effects of the initial sulphur content, the gas flow rate and the slag layer thickness on the desulphurisation efficiency were also investigated. The predicted results show that the desulphurisation efficiency improves with the increase of the initial sulphur content, the gas flow rate and the slag layer thickness. Higher gas flow rate can improve the slag-steel interaction, which, in turn, helps improving the desulphurisation rate. The thinner the slag layer, the larger the slag eyes and the smaller the interfacial area between the slag and steel phases. The consequence is the decrease in the desulphurisation rate.

Numerical Modeling of Liquid–Liquid Mass Transfer and the Influence of Mixing in Gas-Stirred Ladles

“…Singh et al 21 and Hirasawa et al 44 stated that the slag thickness has little or almost no influence on k, meaning that only fluid flow in the metal phase is considered to influence the metalside mass transfer. In contrast, Kim and Fruehan 4 and Cao et al 33 found that a high volume of slag promotes a stronger circulation inside the slag layer. With the numerical approach, it is possible to investigate this phenomenon in greater detail.…”

“…The mixing phenomenon is well-characterized by several experimental 24 and mathematical [25][26][27][28][29][30][31] studies with or without the inclusion of a slag phase. However, an appropriate choice of a liquid-liquid mass transfer model in a CFD study is difficult to ascertain, and so only a few studies 21,32,33 have been conducted on this topic. Singh et al 21 developed a three-phase CFD model to determine the metalslag interfacial area using the VOF approach.…”

“…Costa et al 32 investigated the importance of the sulfur partition coefficient and the thickness of the slag layer on the desulfurization rate, with an input of the mass transfer coefficient based on Incropera and Dewitt's 34 empirical correlation. Recently, Cao et al 33 introduced a full-scale, three-dimensional, transient CFD model using the VOF approach to study the desulfurisation behavior. They adopted a generalized Kolmogorov theory of isotropic turbulence to study mass transfer.…”

Desulphurization Kinetic Prediction into a Steel Ladle by Coupling Thermodynamic Correlations, Fluidynamics and Heat Transfer

“…1,3) Desulfurization is one of the most important operations during the secondary refining process of steel, in practice it is common to use synthetic slag based on CaO and stirring with argon gas in the ladle furnace to improve the reaction kinetics at the interface steel-slag. However, the desulfurization mechanism is complex and depends on several operational variables involved in the process, such as the chemical composition of the slag, [4][5][6] injected gas flow, 7,8) temperature, 9) thickness of the slag layer, 10) refractory lining 11) and the content of dissolved oxygen in the steel. 12) In recent years, Computational Fluid Dynamics (CFD) coupled with kinetic models has been an alternative tool to analyze the behavior of desulfurization in a faster, cheaper and less hazardous way.…”

Physical Simulation of a Nonconsumable Lance for Secondary Refining Operations

“…When the lance is outside the center of the ladle, shorter mixing times are obtained. [1] The study of phenomena, such as the behavior of fluid flow, the mixing efficiency, the opening of the slag layer, [2] the metal-slag reactions, [3,4] desulfurization efficiency, [3,5] and the behavior of inclusions, [6][7][8] have been widely investigated by the use of numerical modeling [2,9,10] as well as mathematical and physical simulation [1,2,[11][12][13][14][15][16] and validated with plant trials. [4] Numerical simulations worked in the modified arrangement of porous plugs and lances placed in an eccentric position at the bottom of the LF.…”