| The behaviors of physico-chemical and metallurgical properties of CaO-MgO-Fe_tO-SiO₂-∑M_xO_y slags which are saturated with MgO and in equilibrium with molten iron were investigated according to the change of MnO content from 2 to 30wt% in the temperature range of 1550 to 1700℃, and discussed in terms of the concept of the optical basicity. The results obtained were summarized as follows; 1) The activity of iron oxide was found to be maximized when the basicity B"=(CaO+MgO+MnO)/(SiO₂+P₂O_5) is 2. And, the activity coefficient of iron oxide approached to unity above 7 of B". 2) The activity of iron oxide was hardly affected by the temperature and the molar ratio of manganese oxide to the sum of basic oxides (MnO)/(CaO+MgO+MnO). 3) The empirical optical basicities of pure FeO, Fe₂O₃ and MnO were derived from the magnesia capacity and the ratio of Fe^(3+)/Fe^(2+) in these stags. The values of those were 0.65, 0.58 and 0.75, respectively. 4) The magnesia capacity, the value of Fe^(3+)/Fe^(2+), the activity coefficient of iron oxide in these stags were expressed by the following equations. log C_(Mg)^(2+)=4.039/Δ(2)-954/T-4.083 log Fe^(3+)/Fe^(2+)=5.085Δ(2)+1367/T-5.194 log γ_(Fe10)=-1.959Δ(5)-2124/T+2.955 |
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