Numerical analysis of effect of current on desulfurization in electroslag remelting process

Abstract

A transient three-dimensional (3D) mathematical model has been established to study the effect of the current on the desulfurization in the electroslag remelting process using direct current (DC). The solutions of the mass, momentum, energy, and species conservation equations were simultaneously calculated by the finite volume method. The movement of the metal droplet was described by the volume of fluid (VOF) approach. In order to include the influences of the slag composition and the current on the desulfurization, a dynamic module of was introduced. Three experiments have been carried out to validate the model. The volume-average temperature of the slag increases from 1 940 K to 2 019 K, while the current ranges from 1 200 A to 2 400 A. The sulfur transfer caused by the slag treatment is promoted by the stronger current because of the higher temperature. The value of the negative transfer rate induced by DC also becomes larger with the increasing of the current. The overall transfer rate at the metal droplet-slag interface is decided by the competition of these two transfer rates. The removal ratio of sulfur increases from 82% to 88% when the current changes from 1 200 A to 1 500 A, and then drops to 65% if the current continuously increases to 2 400 A.