Experimental research and mathematical modelling of the melting and dissolution behaviour of scrap in liquid hot metal

Florian Penz

Research output: ThesisDoctoral Thesis

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Abstract

The production of crude steel, the basis for high quality steels, is mainly carried out with a Linz-Donawitz (LD) converter. During the process, the charged solid scrap is dissolved in the liquid hot metal. In recent years, the dynamic simulation of the entire LD process has become a challenging task. In previous works, a thermodynamic and kinetic model for the LD converter was established. For the description of the dynamic behaviour of the converter process sub routines are core elements of this model. During validation of the model with industrial data the needs for improvement of the sub routine for the scrap melting and dissolution behaviour, were detected. The focal point of this dissertation is the systematic investigation of the scrap melting and dissolution behaviour with the aim of developing a realistic scrap melting approach. The research of the fundamental phenomenological understanding on the dissolution and melting behaviour is part of the present thesis. Based on the theoretical considerations and a comprehensive experimental investigation, a new numerical approach describing the melting and dissolution of scrap was developed. Experiments were carried out under stagnant and turbulent flow conditions. The determination of the heat and mass transfer coefficients was realized through a standardized method of investigating the scrap melting. The findings of the electron microprobe analyses and the metallographic determinations led to a new diffusive scrap melting approach, which is based on the fundamental laws of physical chemistry and thermodynamics. This approach was successfully applied in the global process model. Analytical descriptions of the heat and mass transfer of cylindrical specimens supported the development of a new numerical scrap melting approach. The new numerical model considers a coupled heat and mass transfer and was validated with the experimental investigations. The new approach is valid for the whole operation temperature range of the LD process. A rigid differentiation between diffusive and forced scrap melting as used in the previous sub routine can be avoided with the new model. Also the shell freezing and its melting in the initial stages of the dissolution process is included.
Translated title of the contributionExperimentelle Untersuchung und mathematische Modellierung des Aufschmelz- und Auflösungsverhaltens von Schrott in Roheisen
Original languageEnglish
QualificationDr.mont.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Weiß, Christian, Assessor B (internal)
  • Schenk, Johannes, Assessor A (internal)
Publication statusPublished - 2019

Bibliographical note

embargoed until null

Keywords

  • LD converter
  • heat transfer
  • mass transfer
  • scrap dissolution

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