Kinetics of scrap melting in liquid steel
- PDF / 1,045,232 Bytes
- 10 Pages / 612 x 792 pts (letter) Page_size
- 83 Downloads / 193 Views
I. INTRODUCTION
MELTING is an important process in the steel industry. The melting rate is directly related to energy consumption and furnace productivity. In electric-arc furnace steelmaking, around 60 pct of the total energy requirement is consumed in heating and melting scrap, and more than 50 pct of the time requirement for one heat is used for melting.[1] Several studies have been carried out to investigate the scrap melting in a liquid steel bath.[2–8] In these studies, the melting processes of individual scrap pieces with simple geometries, such as steel cylinders or spheres, were observed, and semiempirical dimensionless correlations were developed to calculate heat- or mass-transfer coefficients between the liquid steel and the solid steel under the conditions of natural or forced convection. While useful, these models have all been limited to one dimension and can only be used to simulate the melting process of an individual scrap piece with simple geometry. In reality, scrap has irregular and complex shapes, and the melting of scrap pieces cannot be simply characterized by melting of a single piece. Moreover, Gaye et al.[7] found that solidified shells form around scrap pieces in the early stages of the melting, possibly causing the agglomeration of scrap pieces, which can have a significant effect on the melting process. The present work undertakes to investigate the kinetics of steel scrap melting, experimentally investigating the effects of size, shape, initial temperature, and oxidation layer of the scrap on its melting behavior in a liquid bath. The study emphasizes the formation and remelting of a solidified shell. A new approach is introduced to model melting, which is based on using the phase-field technique.[10–17] The model is used to elucidate the interplay between the physical mechanisms controlling the kinetics of steel scrap melting. The results of this study will be presented in two articles. The first concentrates on developing an approach for modeling melting of simple shapes in two spatial dimensions. Our model will be validated against melting of cylindrical and square bars. A subsequent article will extend the JIANGHUA LI, Graduate Student, and NIKOLAS PROVATAS, Associate Professor, are with the Department of Materials Science and Engineering, McMaster University, Hamilton, ON, Canada L85 4L7. GEOFF BROOKS, Research Scientist, is with CSIRO Mineral, Victoria 3169, Australia. Contact e-mail: [email protected] Manuscript submitted March 3, 2004. METALLURGICAL AND MATERIALS TRANSACTIONS B
approach taken in this article to include multiple scrap pieces with complex geometries.
II. THEORETICAL CONSIDERATIONS Melting is a dissolution phenomenon in which heat and mass transfer between liquid and solid phases take place. The melting rate can be controlled by heat transfer, mass transfer, or coupled heat and mass transfer, depending on the chemical composition of the solid and liquid phases. For steel scrap melting, the most important solute is carbon, so that the global phenomenon can be com
Data Loading...
