Chemical activities of the solute elements Cu and Sn in scrap-based iron melts

Cu and Sn are harmful elements in steel. Numerous methods for the removal o f these impurity elements from iron-based scrap melts have been proposed an d their feasibility has been confirmed on a laboratory scale. The vacuum di stillation of scrap melts is a promising method of refining with respect to Cu Sn which can find a commercial application in the future. Since the par tial vapour pressure of the evaporating solute elements determines to a gre at extent the efficiency of a vacuum distillation process, knowledge of the chemical activities of Cu and Sn is essential. In this study, the activiti es of Cu and Sn in iron-based melts containing the alloying elements C and Si were calculated with the help of a thermodynamic formalism. The possibil ity to increase the activities of Cu and Sn by alloying the scrap melts wit h C and Si has been discussed on the basis of the calculated results. It wa s proposed to make use of the optimum for the evaporation of Cu and Sn the thermodynamic conditions which exist in ferrosilicon melts.