Study on the Rate of Scrap Melting in the Steelmaking Process

Abstract

A mathematical model has been developed for scrap melting in the steelmaking process based on the concept of simultaneous heat and mass transfer. Steady state equations are established for heat and mass transfer in the boundary layer between solid and liquid. Heat conduction in the solid is expressed by an unsteady state equation. The thickness of diffusion layer and the thickness of scrap are chosen as the required parameters for the calculation. Numerical solutions are obtained by the finite difference method.
The calculation using the values of diffusion layer thickness (5×10^-3-10^-2cm) found by the authors indicates that the present model gives a general agreement with practical data in the case of simple form of scrap.
It is predicted that scrap form and size have an effect on the rate-determining mechanism of scrap melting and on the duration of transient heat conduction in the solid scrap. This is considered to be important in the performance of dynamic control.
It is thought that at the beginning of the process when the temperature of the bath is low and the bath turbulence is weak, iron would solidify on the cold scrap.
A limit of size of scrap for the rapid refining are also discussed.