Basic oxygen furnace

In contemporary integrated ore-based steelmaking, decarburisation of the hot metal produced in the blast furnace is conducted in a basic oxygen furnace. The most common variants of this process are based on the Linz–Donawitz (LD) converter. In this process, the oxidising gas mixture is injected through a supersonic top lance.

Highlights

• A thermodynamic–kinetic simulation tool was developed for the BOF process. The model determines reaction equilibria using the Partitioning of Gibbs Energy (PGE) routine, with the Unified Interaction Parameter (UIP) formalism describing metal-phase non-ideality and the Modified Quasichemical Model (MQM) describing slag-phase non-ideality.
• The generation of droplets by top blowing was investigated experimentally using a physical model. The direction, size and velocity of the droplets were measured directly using shadowgraphy.
• A mathematical model was developed to predict the size distribution of metal droplets ejected by gas-jet impingement. The model describes the droplet ejection sites using harmonic oscillators and determines the upper droplet size limit from a force balance. Owing to its low computational requirements, the model is suitable for incorporation into offline and online BOF simulation tools.
• A mathematical model was developed to predict the residence time of metal droplets in the slag emulsion during BOF steelmaking. The model describes the return of different droplet size fractions to the metal bath and was evaluated using experimental data from industrial converters.
• The applicability of vibration and audio measurements to BOF process monitoring was investigated using data collected from nearly 300 blows. The measured signals were analysed together with process variables to identify relationships between the signal characteristics and process behaviour.

Selected publications

• V.-V. Visuri and L. Holappa, “Converter Steelmaking", Treatise on Process Metallurgy – Volume 3: Industrial Processes (S. Seetharaman, R. Guthrie, A. McLean, S. Seetharaman, and H. Y. Sohn, eds.), pp. 183–241, Elsevier, 2nd ed., 2024
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• J. Nissilä, M. Pylvänäinen, V.-V. Visuri, P. Ruotsalainen, J. Laurila, A. Rankinen, T. Palovaara, and T. Liedes, “Vibration and Audio Measurements in the Monitoring of Basic Oxygen Furnace Steelmaking", Metallurgical and Materials Transactions B, vol. 54, no. 6, pp. 2929–2950, 2023
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• B. Mitas, V.-V. Visuri, and J. Schenk, “Modeling the Residence Time of Metal Droplets in Slag during BOF Steelmaking,” Metallurgical and Materials Transactions B, vol. 54, no. 4, pp. 1938–1953, 2023
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• B. Mitas, V.-V. Visuri, and J. Schenk, “Mathematical Modeling of the Ejected Droplet Size Distribution in the Vicinity of a Gas–Liquid Impingement Zone,” Metallurgical and Materials Transactions B, vol. 53, no. 5, pp. 3083–3094, 2022
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• T. Haas, A. Ringel, V.-V. Visuri, M. Eickhoff, and H. Pfeifer, "Direct Measurement of the Direction, Size and Velocity of Droplets Generated by Top-blowing", Steel Research International, vol. 90, no. 9, 2019. 1900177.
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• A. Kruskopf and V.-V. Visuri, "A Gibbs Energy Minimization Approach for Modeling of Chemical Reactions in a Basic Oxygen Furnace", Metallurgical and Materials Transactions B, vol. 48, no. 6, pp. 3281–3300, 2017.
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