Metallurgical Ladle Research Articles

Model Investigation of Argon Injection into Liquid Steel at Ladle Furnace Station with Using of Innovative Module.

High-quality steels are defined primarily by a small quantity of non-metallic inclusions and a high degree of chemical homogenisation. The ladle furnace (LF) is the most important metallurgical unit in which the quantity of non-metallic inclusions can be significantly reduced while ensuring metal chemical homogenisation. It is achieved largely due to appropriate controlling and the use of increasingly developed inert gas purging techniques. Various types of porous plugs (channel or radial type) are used in the metallurgical ladles. In aggregate units of intermediate-ladle type, various types of channel plugs and/or gas curtains are successfully used. In the research presented herein, a new and innovative module for inert gas injection into liquid steel for deep refining was tested. The presented research relates to the innovative module using to replace the standard porous plug in the steelmaking ladle on the outside-furnace (LF) processing station. Hybrid modelling methods (numerical and physical modelling) were used to carry out research. Module using causes significantly faster alloy additive dispersion in ladle volume compared with the standard solution (the standard porous plug). Furthermore, the obtained flowing structure positively affects liquid steel refining and mixing processes after alloy additive addition. A new technological solution, i.e., gas-injection module-differs from the traditional porous plugs currently used in the steel mills in terms of geometric parameters, external and internal structure, and what is most importantly, terms of the active surface area-shall be understood in as the surface area wherein slots occur.

Selenium as a new decopperization approach for steel scrap

• Copper selenide was formed and located on the oxides after the addition of selenium into the liquid Fe-Cu alloy. • Copper selenide was massively detected in the slag along with the alumina or (Mg, Fe)Al 2 O 4 -spinel. • The detected copper selenide indicate that selenium may be considered as a sufficient approach for the decopperization. Selenium was added into the molten Fe-Cu alloy at 1600 °C to test its decopperization possibility. After the addition of selenium into the liquid Fe-Cu alloy, copper selenide was found to deposit on the particle with a complex composition that located on the solidified alloy sample. Furthermore, a secondary metallurgical ladle slag with a high content of alumina was added into the liquid Fe-Cu alloy after the addition of selenium. Thereby the decopperization efficiency was found to be enhanced by the addition of slag. The copper selenide was massively observed in the slag along with the oxides (alumina or (Mg, Fe)Al 2 O 4 -spinel). The formation of the spinel was predicted by the FactSage software.

Toward a Strong-Sense Validation Benchmark Database for Numerical Ladle Flow Models

In numerical computation of ladle metallurgy, multiphase models are essential. Still, these models are afflicted with great uncertainty, making a validation with experimental data mandatory. Validation experiments fundamentally differ from physical modeling experiments because emphasis is on a complete documentation of all boundary conditions and a detailed uncertainty assessment. For this work, the experimental design for a comprehensive accuracy assessment of numerical models and reported quantities were jointly determined with international numerical experts. The framework comprises a plume analysis and flow measurements in the single- and multiphase regions of a water model with defined conditions. All influencing factors are documented extensively and their contribution to the overall data uncertainty is quantified. Detailed data are made publicly available within a validation benchmark database for isothermal multiphase flow in metallurgical ladles. A first draft of a standardized validation procedure, including a single number validation score, is proposed. Using the available data, the accuracy of numerical models can be quantified more accurately and comparably, which helps in advancing the model’s further development. It also lays the foundation for a standardization of the validation process, which can lead to greater acceptance of the numerical results.

Physical and Mathematical Modelling of Mass Transfer in Ladles due to Bottom Gas Stirring: A Review

Steelmaking involves high-temperature processing. At high temperatures mass transport is usually the rate limiting step. In steelmaking there are several mass transport phenomena occurring simultaneously such as melting and dissolution of additions, decarburization, refining (De-P and De-S), etc. In ladle metallurgy, refining is one of the most important operations. To improve the rate of mass transfer bottom gas injection is applied. In the past, most relationships between the mass transfer coefficient (mtc) and gas injection have been associated with stirring energy as the dominant variable. The current review analyzes a broad range of physical and mathematical modeling investigations to expose that a large number of variables contribute to define the final value of the mtc. Since bottom gas injection attempts to improve mixing phenomena in the whole slag/steel system, our current knowledge shows limitations to improve mixing conditions in both phases simultaneously. Nevertheless, some variables can be optimized to reach a better performance in metallurgical ladles. In addition to this, the review also provides a state of the art on liquid–liquid mass transfer and suggests the current challenges in this field.

Materials selection of furnace linings with multi-component refractory ceramics based on an evolutionary screening procedure

Materials selection of multi-component systems is a challenging task, which is usually not properly tackled in furnace linings (FL) design. In an attempt to generate a systematic approach to select FL ceramic materials, an evolutionary screening procedure (ESP) is proposed in this paper, where a multi-objective genetic algorithm coupled with a finite element model aims to transform a list of potentially feasible ceramic candidate materials into an optimized set of multi-component systems simultaneously computing external lining temperatures and costs. An ESP-based selection methodology is proposed and studied in light of a case-study concerning an electric resistance furnace. A customized initial screening was carried out to select potential single candidate materials to be used. Next, the ESP was used to select optimized lining configurations while discarding infeasible combinations, such as those in which one of the materials maximum allowed temperature had been breached. Afterwards, TOPSIS (a multi-criteria decision-making approach) was applied to rank the optimized results according to some furnace preference scenarios. The ESP-based selection diminished a universe of 1.9×105 lining configurations into a few units to be investigated in more details by simulating only 3.8% of them, thus requiring reduced amount of time for completing this task. The adopted quantitative strategy uses commonly used computational techniques and could be applied to metallurgical ladle linings, be adapted to select raw materials or resolve other complex decision-making problems in the ceramic community.

A novel dual plugs gas blowing mode for efficient ladle metallurgy

ABSTRACTA novel gas blowing mode with different flowrates for two plugs of metallurgical ladle is explored and studied through a sophisticated water model. The results show that this mode can efficiently decrease the mixing time and the total area of the slag eye for most cases, as compared with the conventional mode with same flowrates for two plugs. Generally, a relatively close angle between the porous plugs and a small radial position are beneficial to a decrease in the mixing time of bath, while a relatively far plug radial position leads to a smaller slag eye. In addition, tracers fed from the middle of the dual plugs are proven to be very beneficial to the mixing of the ladle. The slag layer will prolong the mixing time due to its consumption on the stirring energy compared with the situation without slag.

A Theoretical Scaling Equation for Designing Physical Modeling of Gas-Liquid Flow in Metallurgical Ladles

A Theoretical Scaling Equation for Designing Physical Modeling of Gas-Liquid Flow in Metallurgical Ladles

Effect of Nozzle Diameter on Mixing Time During Bottom-Gas Injection in Metallurgical Ladles

The improvement of mixing conditions in metallurgical vessels is of fundamental importance to increase furnace productivity, steel cleanliness, removal of impurities, and so on. Water modeling has been used to investigate mixing phenomena; however, there is still a need to clarify the role played on mixing time by process variables such as the nozzle diameter to properly represent the real process conditions. In water modeling design, this parameter is usually ignored. The current investigation has found that changes in nozzle diameter affect mixing time; however, the extent of this effect is influenced by nozzle radial position and gas flow rate. The conditions to minimize mixing time with one nozzle and a top layer of 2 pct have also been identified.

Thermochemical Calculation of the Quaternary CaO–SiO2–Al2O3–MgO System at 1600°C for Predicting the MgO‐Saturation and MgO–MgO · Al2O3 Equilibrium of Secondary Metallurgical Slag

Different quaternary CaO–SiO2–Al2O3–MgO systems were calculated with thermochemical‐calculations at various temperatures by using FactSage6.2. The calculated systems provide enhanced knowledge of secondary metallurgical ladle slag conditions at process temperatures. These systems can also be used for predicting the MgO‐saturation and the MgO–MgO · Al2O3 equilibrium at various temperatures for commonly used ladle slag compositions.

Diagnosis of Metallurgical Ladle Refractory Lining Based on Non-Stationary On-Line Data Processing

Abstract A new method for diagnosis of the remaining thickness of metallurgical ladle refractory lining working in a batch mode is proposed, where directly measured by a thermovision camera data about the amplitude and phase delay of the maximum surface temperature is used. Regression equations are obtained to determine the remaining thickness of the ladle refractory lining depending on the parameters of steady auto oscillations of the maximum surface temperature. It is shown that the data from nonstationary auto oscillations could be used for adaptation of the regression equations, predicting the remaining thickness of the ladle refractory lining in case of a local damage.

Development and Application of Shotcreting Castable for Steel Ladle

The article mainly introduct the development and application of shotcreting castable for metallurgical steel ladle. The shotcreting castable mainly use tabular alumina, white fused corundum, fused spinel, aluminate cement, alumina micro powder, fused magnesium as raw material, After studied by the workability and physical properties of gunning machine, it is proved by application in steel ladle, the shotcreting castable has a good workability, with higher adhesive rate, faster hardening speed, better thermal shock resistance and stronger erosion resistance ability. So the shotcreting castable has a higher service life.

Identificação e avaliação dos mecanismos de ataque da escória SiO2-CaO-Al2O3-MgO em tijolos refratários de MgO-C

O presente trabalho tem como objetivo identificar e caracterizar mecanismos responsáveis pelo desgaste dos tijolos refratários de magnésia-carbono de uma panela de aciaria, devido ao ataque da escória SiO2-CaO-Al2O3-MgO. Para tanto, tijolos refratários MgO-C utilizados na linha de escória de uma panela industrial foram comparados com tijolos após o uso (post mortem). A microestrutura da região interfacial escória / refratário foi avaliada por análises mineralógicas (difração de raios X), microscopia eletrônica de varredura e microscopia óptica (lâminas petrográficas). Foi possível constatar que o tijolo post mortem apresenta, além das fases já existentes in natura, novas fases como a alumina, o silicato de cálcio e a gelenita devido à sua reação com a escória. Os resultados sugerem que o principal meio de degradação do tijolo se estabeleça pela infiltração da escória na matriz entre os grãos do tijolo refratário. Isto ocasiona o arrancamento de grãos, comprometendo a microestrutura original do material refratário, diminuindo seu tempo de vida útil.

“MAPEKO” Company in the world market of equipment for drying, heating, and thermostatic control of metallurgical ladles and blast furnace runners

Engineering and process aspects of development and position of the “MAPEKO” Company in the international market of equipment for the steel-melting industry are presented. Specialization of the company, its engineering policy, innovative activities, general types of produced equipment, performance characteristics of the latter, and methodological and organizational principles of the work with customers are described.

The possibility of repair of metallurgical ladle lining

Metallurgists have always dreamed of an “eternal ladle”, i.e., the possibility of repairing a metallurgical ladle without removing its old lining. However, the use of thick mixtures for this purpose is problematic, whereas thinner mixtures are prone to cracking under cooling. The author demonstrates that the reason for such cracking is the temperature contraction of the surface layer, which is the first to be cooled, as a consequence, a larger volume becomes enclosed in a shell of a smaller capacity, which leads to its cracking. A method is proposed for cooling the inner volume of lining to remove temperature stresses from the outer layers and prevent their cracking.

Drag and non-drag force influences in numerical simulations of metallurgical ladles

The modeling of metallurgical gas stirred ladles involves the interaction between several different phases with effects that, in many cases, have been considered in the literature. However, the way in which the different non-drag effects influence the behavior of this system is not clear. In this paper we analyze how numerical results are affected when the parameters used in modeling non-drag forces (such as virtual mass, lift, and turbulent dispersion force) are varied. Other effects such as the increment in turbulence due to the bubbles, a deformable free surface, and the influence of the bubble size were also considered. The knowledge of the way in which each physical phenomenon modifies the behavior of the main variables of the system allowed the fitting of experimental data in a variety of conditions. We conclude that a gas stirred ladle can be properly represented when the non-drag effects analyzed here are included, and give suitable values for the different parameters considered.

An Analytical Solution Method for Composite Layer Diffusion Problems with an Application in Metallurgy

An analytical solution method for composite layer diffusion in cylindrical geometry is studied, relying on local analytical solutions for the single material layers combined with a numerical solution scheme for the material boundary states. The one-layer submodel was formulated for one-dimensional geometry and constant material properties. An efficient algorithm for the arising local Sturm-Liouville eigenvalue problems is developed on the basis of the calculus of variations and the JWKB-technique known from quantum mechanics. Two example heat conduction calculations of the temperature profile over a composite solid were carried out. The results of the examples were in satisfactory agreement with those of previously published calculations using alternative methods. This, together with the computational benefits of obtaining the eigenvalue spectrum for the composite medium one layer at a time, demonstrates the feasibility of the adopted technique for situations requiring an analytical solution. The method was applied to thermal state computation for the lining of a metallurgical ladle, the results showing good consistency with thermocouple measurements.

Developments in modelling of gas injection and slag foaming

Gas injection into metallurgical ladles has been an active area of CFD modelling for many years. Recent work with both Eulerian and Lagrangian frameworks is presented for bottom stirring in ladle and steelmaking electric furnace configurations. Comparison with water and liquid metal results shows that the Lagrangian models provide a better representation of the systems. Slag foaming is an important phenomenon in smelting–reduction processes and electric furnace steelmaking. The void fraction in the foam is generally greater than 0.9, a regime that has received considerably less attention than bottom stirring where the local void fraction is less than 0.1. Again, it was found, by comparison with experimental data, that Lagrangian models were generally preferable over Eulerian models.

Model for temperature profile estimation in the refractory of a metallurgical ladle

Modeling of the transient thermal state of metallurgical ladels is motivated by the need for estimating the drop in temperature of the liquid metal in the ladle. On-line estimation of the state is required, since the same ladle is used in a number of casting cycles with rapid changes in boundary conditions for the temperature field, and the conditions in the current as well as previous cycles affect the thermal state. Although a large number of methods for the numerical solution of conduction-diffusion partial differential equations have been developed, there are still advantages to keeping thermal field computations at a relatively simple level, in contrast to the situation in the design process of ladles, where two-dimensional modeling may be required. Extensive computations under nonverifiable boundary and initial parameter values are not especially suited for real-time simulation of industrial processes. This article presents a novel approach to the solution of the one-dimensional transient heat conduction problem applied to ladle linings, relying on classical analytical techniques in combination with numerical methods. The performance of the model was validated by a comparison of predictions to thermocouple measurements from the refractory of a steelmaking ladle during a campaign of 26 casting cycles. Reasonable agreement between the measured and simulated variables could be established, which demonstrates the feasibility of the approach.

A Mathematical Model of the Heat Loss of Steel in a Metallurgical Ladle

A mathematical model suitable as a tool for improving temperature control in the steel plant is presented. With this tool, a number of variables such as holding time, material choice and refractory layer thicknesses can be studied with regard to their influence on the steel temperature evolution during casting. In addition, the model can be used as a decision support and forms a basis for automation of temperature control.

Characteristics of eccentric bubble plumes in liquids

The hydrodynamics of air/water plumes in a large scale model of a metallurgical ladle was investigated. The dimensions of the cylindrical vessel were 1600 mm i.d. and 2250 mm total height. The air was injected through an eccentric nozzle positioned halfway between the center and the wall of the vessel. The gas concentration, bubble frequency, and liquid and gas velocities were measured using electrical resistivity probes and a propeller flowmeter. Particular attention was paid to the liquid velocity. Its field is complex and nonstationary. Light scattering experiments on a small scale model were carried out to supplement the velocity data measured in the large vessel. From the analysis of the data, it was found that the maximum values of the gas fraction (time average), the upward liquid velocity, and the gas velocity can be described with the same dimensionless correlations derived previously for the centered plume.