Auflösungsverhalten von Schrott in Roheisen unter Schutzgasatmosphäre

Translated title of the contribution: Dissolution behavior of scrap in pig iron under a protective gas atmosphere

Alexander Halwax

Research output: ThesisMaster's Thesis

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Abstract

Within this master thesis, the dissolution behavior of three different scrap types in liquid hot metal was investigated at an equilibrium temperature of 1300 ° C under inert gas. The aim was to investigate the influence of the carbon concentration difference between scrap and liquid hot metal on the dissolution behavior of the scrap. The results were compared with previous tests, which were carried out under oxidizing conditions. From the comparison, the influence on the dissolution behavior of the scrap by the oxidation of the samples was evaluated. By means of a heat balance the self-adjusting equilibrium temperature was calculated and from this the necessary initial temperature of the liquid hot metal was determined. The required values for the enthalpy and specific heat capacity were determined using FactSage® 7.2 and the databases FSstel and FactPS. In addition to the equilibrium temperature, the density of the scrap at equilibrium temperature was determined by an equation published by Miettinen in [1]. The dissolution experiments under inert gas atmosphere were carried out in a high temperature vertical tube furnace at the chair of ferrous metallurgy. As a protective gas nitrogen was used in all experiments. After the experiments, the resulting radii were determined about the mass loss of the samples using a goal seek application with Microsoft® Excel. The resulting radii were calculated using a second-order Lagrange-polynomial to calculate the ablation rate and the mass transfer coefficient according to the approach published by Zhang and Oeters in [2]. Since the dissolution process of scrap is a coupled heat and mass transport, a metallographic examination of the samples was performed to determine the thickness of the boundary layer. The comparison of the ablation rates, mass transfer coefficients and boundary layer thicknesses with literature values gave different results. The comparison showed that the removal rate and the mass transfer coefficient are apparently not affected by oxidizing conditions in earlier experiments. The determined diffusion depths of the carbon in the solid scrap differ from previous results. This is a result of the slow cooling rate of the samples in the vertical tube furnace. In previous works the sample surface is affected by the oxidation.
Translated title of the contributionDissolution behavior of scrap in pig iron under a protective gas atmosphere
Original languageGerman
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Schenk, Johannes, Supervisor (internal)
  • Penz, Florian, Co-Supervisor (internal)
Publication statusPublished - 2020

Bibliographical note

embargoed until null

Keywords

  • Scrap dissolution
  • Protective gas atmosphere
  • Mass transfer coefficient

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