Über die Roheisenraffination der schäumenden Emulsion im LD-Tiegel

Translated title of the contribution: The refining contribution of the foamy emulsion during the LD-Process

Bernhard Mitas

Research output: ThesisDoctoral Thesis

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Abstract

The predominant steelmaking route is the Linz-Donawitz (LD) converter route. Since about 70 years the LD-converter (basic oxygen furnace, BOF) is used successfully to refine the hot metal originating from the blast furnace. Despite the economic importance of the process and the processes maturity, various aspects of the process are not fully understood. There is still disagreement among research groups regarding the relative contribution to decarburization of the hotspot and the emulsion. Consensus has been only reached for the beginning and the end of the blowing process, where emulsion decarburization is assumed to contribute subordinate refining performance compared to the hot spot. A well-studied phenomena is the liquid ejection close to a gas-liquid impingement area. The assessment of the hot metal ejection rates due to the oxygen jets impingement on the surface of the hot metal is performed in this work due to the lack of condense of published empirical ejection correlations when applied to industrial sized converter vessels. Physical boundaries are formulated to evaluate the mass ejection correlations presented in the literature. The refining of the slag-metal emulsion during BOF steelmaking is evaluated. Having established models for the prerequired emulsion creation phenomena, refining predictions can be determined. The models were systematically positioned at various locations downstream from the oxygen jets. Using a mathematical model, the geometry of the hotspot cavity can be predicted and an additional model analyzing the shear induced droplet generation is presented in this research. Based on presented publications, regarding ejected droplet size distribution and the residence time of droplets in the slag vital refining parameters of the BOF process are analyzed and discussed. The droplet size distribution model predicts significant larger droplets compared to droplet sizes used by various researchers in the literature when modeling dynamic BOF behaviors. The coupled micro- and macro kinetic model depicts that the large droplets that have previously not been included in modeling contributes a significant fraction of the refining of the hot metal phase. Calculations using the developed foamy-slag model depicted a limit for the emulsion decarburization fraction. It is estimated that slopping will occur if the actual emulsion decarburization fraction exceeds 25%.
Translated title of the contributionThe refining contribution of the foamy emulsion during the LD-Process
Original languageGerman
QualificationDr.mont.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Lehner, Markus, Co-Supervisor (internal)
  • Odenthal, Hans-Jürgen, Assessor A (external), External person
  • Schenk, Johannes, Supervisor (internal)
  • Visuri, Ville-Valtteri, Assessor B (external), External person
DOIs
Publication statusPublished - 2024

Bibliographical note

no embargo

Keywords

  • LD
  • BOF
  • basic oxygen furnance
  • foamy emulsion
  • modeling
  • modelling
  • steelmaking

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