Mathematical Expression of Manganese Distribution in Steelmaking Process by Quadratic Formalism Based on Regular Solution Model

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In the present work, an approximate validity of the regular solution model for slag was studied to formulate the equilibrium relation of manganese distribution for all the experimental results including the present work and the other previous studies, in succession to the successful application of the model for oxygen and phosphorous distribution between slag and metal in steelmaking process.In the first step, measurements of the iron oxide activity in MnO-bearing slags have been made to evaluate the effects of slag components on the manganese distribution between slag and metal in steelmaking process. For this purpose, the chemical equilibria were determined among solid iron, H_2/H_2O gas mixture and ternary Fe_tO-SiO_2-MnO or quaternary Fe_tO-SiO_2-MnO-M_xO_y (M_xO_y = CaO, MgO, Na_2O, P_2O_5) slags to determine the values of the interaction energies between cations, where Fe_tO-Sio_2-MnO is a fundermental system when we consider the manganese distribution, and CaO and MgO are basic … More slag components in steelmaking process, and Na_2O is used as simultaneous agent for dephosphorization and desulphurization not only in hot metal treatment but also in secondary refining of steel, and P_2O_5 is product in dephosphorization process.In the second step, the manganese distribution between slag and liquid iron has been studied under Ar atmosphere at the temperatures from 1550 to 1650 ゜C. The slag systems studied at present work were of Fe_tO-SiO_2-MnO sturated with (Mn,Fe)O, Fe_tO-SiO_2-MnO-MgO saturated with (Mg,Fe,Mn)O or 2(Mg,Fe,Mn)O・SiO_2 and Fe_tO-SiO_2-MnO-CaO saturated with (Ca,Mn,Fe)O, in order to make sure the validity of the model. The previous data employed to check the applicability of the model to manganese distribution were the experimental results by Krings et al., Maurer et al., Korber et al. Chipman et al., Bell et al., Fischer et al. and Suito et al..From the results obtained, it was confirmed that the regular solution model was satisfied for all the experimental results including the present work and the previous studies by other investigators except for extremely iron oxide rich region.From the equilibrium relation obtained, the manganese distribution ratio, L_<Mn> = (%MnO)/[%Mn], the activities and activity coefficients of slag constituents can be calculated as a function of slag composition and temperature. The manganese and oxygen contents in iron in equilibrium with the slag can be evaluated within the accuracy of <plus-minus> 10 % from the model. Less