Oxidation-Reduction Equilibrium of Manganese in CaO-MntO-SiO2 Slags

The oxidation-reduction equilibrium of manganese in the CaO-Mn 1 O-SiO 2 (-MgO-Al 2 O 3 ) slag system has been investigated as functions of slag composition, oxygen partial pressure and temperature. In the range of oxygen partial pressure of 3.04 to 21.28 kPa and temperature of 1 573 to 1 673 K, the (%Mn 3+ )/(%Mn 2+ ) ratio was determined and expressed by the following equation: log(%Mn 3+ )/(%Mn 2+ ) = 0.86{(%CaO) + (%MgO) + 0.436(%Mn t O) + 0.126 (%Al 2 O 3 )}/ (%SiO 2 ) + 0.22 log P O2 (Pa) + 2 860/T- 4.44 The value of standard enthalpy change for the oxidation of Mn 2+ to Mn 3+ was determined to be -55kJ/mol. The manganite capacity, C MnOx , has also been arranged as a function of slag composition and temperature. Furthermore, on the basis of the present experimental data, the values of optical basicity of component oxides were estimated and compared with those reported by the other investigators.