Effect of slag composition on desulfurization during recycling rejected electrolytic manganese metal by electroslag remelting

Abstract

To reduce the Mn vaporization during recycling rejected electrolytic manganese metal by electroslag remelting, it is proposed to reduce the temperature of molten slag pool, but which leads to the degradation of slag desulfurization. The desulfurization by interaction between CaF2 –CaO–Al2 O3 –Na2 O slag and rejected electrolytic manganese metal scrap was studied from the view of thermodynamics in this study. The results show that sulfur distribution ratio decreases with increase of CaF2 content, and increases with the increase of Na2 O content and temperature. Na2 O increases sulfur distribution ratio of slag by increasing CaO activity. Na2 O addition in CaF2 –CaO–Al2 O3 –Na2 O slag can enhance desulfurization ability of slag due to the larger sulfur distribution ratio and lower viscosity. Thus, sulfur content in test of slag T3 bearing 45.8 wt% CaF2 -23.2 wt% CaO-22.7 wt% Al2 O3 -8.3 wt% Na2 O is much lower than that of slag without Na2 O, implying that 45.8 wt% CaF2 -23.2 wt% CaO-22.7 wt% Al2 O3 -8.3 wt%Na2 O slag is the promising slag for recycling rejected electrolytic manganese metal by ESR.