Development of an Electrochemical Method to Investigate the Thermodynamic Behavior of Lanthanum and Sulfur in Liquid Steel

Abstract

Since rare earth elements (REE) have great potential to improve mechanical properties of steel by refining grains and controlling the distribution and the shape of inclusions, REE may be widely used in steel industry. Currently, the method for REE separation is solvent extraction. Since this method has economic and environmental problems, more efficient process is strongly required. In this study, I look at vacuum distillation of RE sulfide. The challenge is that thermodynamic data of RE sulfide of gas phase are insufficient. Therefore, I investigated the thermodynamic properties of gaseous rare earth compounds to evaluate the feasibility of vacuum distillation of RE sulfide, here during the steelmaking process. To study the thermodynamic behavior of REE, especially La in liquid steel at high temperature, an electrochemical method (EMF) using Laβ” Al2O3 solid electrolyte has been developed and its performances are herein discussed.