A Review of Physical and Numerical Approaches for the Study of Gas Stirring in Ladle Metallurgy

Abstract

This article presents a review of the research into gas stirring in ladle metallurgy carried out over the past few decades. Herein, the physical modeling experiments are divided into four major areas: (1) mixing and homogenization in the ladle; (2) gas bubble formation, transformation, and interactions in the plume zone; (3) inclusion behavior at the steel-slag interface and in the molten steel; and (4) open eye formation. Several industrial trials have also been carried out to optimize gas stirring and open eye formation. Approaches for selecting criteria for scaling to guarantee flow similarity between industrial trials and physical modeling experiments are discussed. To describe the bubble behavior and two-phase plume structure, four main mathematical models have been used in different research fields: (1) the quasi-single-phase model, (2) the volume of fluid (VOF) model, (3) the Eulerian multiphase (E-E) model, and (4) the Eulerian-Lagrangian (E-L) model. In recent years, the E-E model has been used to predict gas stirring conditions in the ladle, and specific models in commercial packages, as well as research codes, have been developed gradually to describe the complex physical and chemical phenomena. Furthermore, the coupling of turbulence models with multiphase models is also discussed. For physical modeling, some general empirical rules have not been analyzed sufficiently. Based on a comparison with the available experimental results, it is found that the mathematical models focusing on the mass transfer phenomenon and inclusion behaviors at the steel-slag interface, vacuum degassing at the gas-liquid interface, dissolution rate of the solid alloy at the liquid-solid interface, and the combination of fluid dynamics and thermodynamics need to be improved further. To describe industrial conditions using mathematical methods and improve numerical modeling, the results of physical modeling experiments and industrial trials must offer satisfactory validations for the improvement of numerical modeling.

Effect of Differentiated Injection Ratio, Gas Flow Rate, and Slag Thickness on Mixing Time and Open Eye Area in Gas-Stirred Ladle Assisted by Physical Modeling

“…Accordingly, there has been a great interest to understand the effect of different process parameters on the mixing time in ladles, [2][3][4] including the gas flow rate, the number of plugs, the radial and angular position of the plugs in systems with multiple gas injection points, the presence or absence of slag, the thickness of the slag layer, and the diameter of the plugs, among other variables. The gas flow rate is by far the variable affecting the most the mixing time and it is well known that the larger the gas flow rate the shorter is the mixing time obtained in ladles.…”

Physical and Numerical Modelling on the Mixing Condition in a 50 t Ladle

“…For the ±5% homogenization degree case, the mixing time was determined as the concentration of the tracer, which was continuously within ±5% of a well-mixed bulk value. [2] The procedure was the same for the case of a ±1% homogenization degree case, but the mixing time corresponded to a ±1% well-mixed bulk value. The configurations of porous plugs and conductivity probes in the mixing experiment are shown in Figure 5.…”

“…The solid and dashed lines represent the tracer concentration within ±5% and ±1% of the homogenization degrees' value, respectively. For the ±5% homogenization degree case, the mixing time was determined as the concentration of the tracer, which was continuously within ±5% of a well-mixed bulk value [2]. The procedure was the same for the case of a ±1% homogenization degree case, but the mixing time corresponded to a ±1% well-mixed bulk value.…”

“…In ladle metallurgy, the mixing pattern has a large influence on the alloying time. Moreover, the inclusion removal and chemical reactions are also closely related to the flow distribution [1,2]. In order to optimize the process, argon bubbling is widely used to enhance the stirring conditions.…”

A Novel Multiphase Methodology Simulating Three Phase Flows in a Steel Ladle

“…They stated that this limitation is however compensated by a low dependency of heat and mass transfer rates on turbulence inside the ladle. Detailed reviews of modeling-based simulation studies in ladles can be found in [2][3][4].…”