Investigation of inclusion re-entrainment from the steel-slag interface

Abstract

The mechanism of inclusion elimination from continuous steel casting is investigated at the steelslag interface. Inclusion impact at the interface is considered under the concept of energy balance, with buoyancy forces, fluid dynamic forces, interfacial adhesion, and rebound forces determining whether the particle will pass through the interface or be retained by it. The effects of the inclusion, slag, and steel properties, as well as the effect of inclusion impact velocity, are considered at the interface. The interfacial tension between the slag and the inclusion should be smaller than that between the steel and the inclusion (negative wettability), so that the inclusions can pass into the slag layer and avoid re-entrainment. The inclusion particles that reach an equilibrium state at the steel-slag interface are subject to re-entrainment back into the steel, due to lift forces applied to them by the turbulent boundary layer at the interface. A removal criterion dependent upon the shear stress is introduced, and then the removal rates are calculated from the turbulent burst theory. It is found that the smaller diameter inclusions are trapped at the interface. Of the particles that remain at the interface, it is the larger ones that are more easily removed by the lift forces due to the turbulent shear stress. High slag viscosity is desirable, since it makes inclusion re-entrainment into the casting product more difficult.

Effect of Operating Conditions on Inclusion of Die Steel during Electroslag Remelting

“…It indicates that the bigger inclusions are more easily to be removed than smaller ones. Similar to the current findings, Bouris et al 23) reported that the larger inclusion can be more easily removed than smaller one.…”

Mathematical Modeling of Iron and Steel Making Processes. Mathematical Modeling of Fluid Flow in Continuous Casting.

“…Phenomena such as these are difficult to measure or to accurately quantify with a physical model, so are worthy of mathematical modeling. For example, a model of inclusion entrainment from the slag layer was developed by Bouris et al 132) …”

Modelling of Inclusion Motion and Flow Patterns in Swirling Flow Tundishes with Symmetrical and Asymmetrical Structures

“…Considering water modeling conditions, the walls are set as reflection boundary in this work for comparison of separation ratios of inclusion in SFT and a tundish with TI. Although most reports assume that the free surface is a trap boundary, there is a possibility of re-entrainment 18) to be considered. Given that the fluid is incompressible (i.e.…”