ISIJ International vol:48 issue:10 pages:1331-1338
The Mn and Cr equilibria between a Mn rich stainless steelmaking slag (CaO-SiO2-MgOsat.-MnO-CrO1.5) and Fe-Cr-Mn stainless steel were investigated in a temperature range from 1 823 to 1 873 K under Ar atmosphere. The partition ratios L-Mn and L-Cr between liquid slag and steel were determined as a function of slag composition and temperature, By combining the experimental results with thermodynamic calculations, it was found that, as basicity increases, L-Mn decreases, while L-Cr increases. The elevated basicity leads to a high MnO activity coefficient. On the other hand, the CrO1.5 activity coefficient decreases with higher slag basicities. The influence of MnO and CrO1.5 contents on the activity coefficients was also considered. It is concluded that in order to maximize Mn recovery during high Mn stainless steel production, a basic slag with a high MnO activity coefficient must be employed whereas high temperatures should be avoided.