Interaction Coefficients of Cu and Sn with Mn in Molten Iron at 1873 K

Abstract

Regarding the depletion of high-grade iron ore and an increase in steel scrap, a new ironmaking process that can utilize both low-grade iron ores and steel scraps is expected. When steel scrap is used as an iron source, tramp elements, such as Cu and Sn, are dissolved in hot metal. The tramp elements can affect the hot metal composition due to the thermodynamic interaction between tramp elements and other alloying elements. However, the thermodynamic interaction between Cu and Sn with Mn has not been known enough. In this work, the interaction coefficients between Cu and Sn with Mn were measured at 1873 K by a chemical equilibration technique using the liquid immiscibility of Fe and Ag as follows:

ε^Cu_{Mn(in Fe)} = −4.30 ± 0.78,

e^Cu_{Mn(in Fe)} = −0.016 ± 0.003,

ε^Sn_{Mn(in Fe)} = −5.21± 0.55,

e^Sn_{Mn(in Fe)} = −0.008 ± 0.001

Moreover, the effects of scrap ratio (iron mass ratio of scrap to scrap and sinter) on hot metal and molten slag composition were thermodynamically analyzed considering the interaction coefficients measured in this work. When the scrap ratio was increased, the copper and tin contents of hot metal were increased, leading to the increase in the Mn content of the hot metal. However, the Mn content of hot metal was decreased by increasing the scrap ratio because the input amount of MnO was reduced.