Dissolution of Scrap in Hot Metal under Linz–Donawitz (LD) Steelmaking Conditions

Abstract

One of the main charging materials of the Linz–Donawitz oxygen steelmaking process (LD) is scrap. Scrap acts as a coolant for the exothermic reactions inside the LD vessel and as an iron source in addition to hot metal. The optimization of the LD process is focused, amongst other factors, on thermodynamic and kinetic modelling. The results of simulations have to be validated in close to reality laboratory-scale experiments. A study was made on the dissolution behavior of common steel scrap in carbon-saturated hot metal which is charged into LD converters. In order to examine the effect of several parameters on diffusive scrap melting, the difference between stagnant and dynamic dissolution as well as the influence of the hot metal temperature were investigated. Using a literature-based equation the mass transfer coefficient of carbon between the solid scrap and the liquid hot metal was evaluated. The ranges of values of the ablation rate and the mass transfer coefficient for the appropriate systems are pointed out, resulting in a significant dependence of the investigated parameters.

A Review of Steel Scrap Melting in Molten Iron‐Carbon Melts

“…They based their assumption concerning turbulent conditions on geometric and physical parameters of the experiment using the theory of Taylor‐Couette flows. Based on the published system, a turbulent mixing regime was established . The mass transfer coefficients are listed in Table and are comparable in the range of previous investigations using a similar experimental setup …”

“…Penz et al carried out dissolution tests using S235JR construction steel samples in hot metal in ref. They reported that after 20 s of immersion time, the core of the specimen has the same temperature as the liquid hot metal; thus, only mass transfer is in action. Similar results were also reported by Penz et al .…”

“…In ref. the mass transfer was estimated through the relation based on Equation of Lommel and Chalmers, deduced by Oeters and Zhang . Their published ranges of mass transfer for experimental temperatures of 1230, 1300, and 1385 °C under natural convection are comparable to the range put forth by previously mentioned researchers in ref.…”

“…Penz et al in addition to their investigations under natural convection, also reported forced convection measurements in ref. . In order to realize turbulent conditions in the hot metal, they rotated the sample at 100 rpm.…”

“…An overview to the phenomenological understanding as well as theoretical considerations will lead into the research topic in the first two chapters. Further, this review classifies the past research work into the following categories: Single mass transfer experiments Heat transfer experiments Simultaneous heat and mass transfer in small‐scale experiments Simultaneous heat and mass transfer in converter experiments Modeling of scrap melting …”