Thermodynamics of Mn-O Interactions in Liquid Copper Alloys and Activities of MnO in MnO-SiO₂ Slag

Abstract

As a provision for measuring the thermodynamic data of high MnO slag by equilibrating with liquid copper in the temperature range of hot metal pretreatment, thermodynamics of manganese-oxygen interactions in liquid Cu-Mn alloy were investigated. The liquid alloys containing 0.2-1.0 mass% Mn were equilibrated with solid MnO in a molybdenum crucible under an argon atmosphere. The following equations for the interaction coefficient (f_O^Mn) were obtained for the range of 0.2-1.0 mass% Mn.

logf_O^Mn=-0.8122-1.27[%Mn]+0.37[%Mn]² at 1573 K
logf_O^Mn=-0.7536-1.14[%Mn]+0.33[%Mn]² at 1623 K
logf_O^Mn=-0.6189-1.07[%Mn]+0.37[%Mn]² at 1673 K

Using the above values of logf_O^Mn, the activities and activity coefficients of MnO in MnO-SiO₂ slag were determined at 1673 K and examined in comparison with the values reported by other investigators.