CONTRIBUTION OF ELECTROCHEMICAL REACTIONS TO SULFUR TRANSFER FROM ELECTRODE TO SLAG IN ELECTROSLAG REMELTING

In order to assess the contribution of electrochemical reactions to refining reactions, such as sulfur removal, in electroslag remelting, electrochemical experiments which simulate conditions at the electrode/slag, and liquid metal pool/slag interfaces have been carried out. Liquid copper electrodes and a CaO-Al2O3-CaF2 electrolyte were used. The experimental technique involved chronopotentiometry at constant current. Sulfur reversion from slag to metal is shown to be a diffusion controlled, reversible electrochemical process involving two electrons. On the other hand sulfur transfer from metal to slag occurs both by the diffusion controlled electrochemical reaction and the direct exchange reaction. A hanging drop electrode system was used to simulate conditions at the electrode/slag interface. Further experiments on the hanging drop electrode with and without applied current showed that direct reaction was a minor contribution to sulfur removal. The results are compared to findings from industrial practice. © 1979 American Society for Metals and the Metallurgical Society of AIME.