MnO₂ を含む石灰系フラックスによる溶銑の脱りん及び脱硫

抄録

Experiments have been performed to study dephosphorization and desulphurization of desiliconized hot metal (Si=0.12%) by CaO-based flux containing MnO₂ (CaO-CaF₂-MnO₂-Fe₂O₃ system) in a magnesia crucible at 1 350°C
It is found that the flux is more effective for dephosphorization and desulphurization that the CaO-CaF₂-Fe₂O₃ system and that manganese content in hot metal can also be increased. In the slag, as the activity of lime is unity, further addition of CaO content is ineffective for dephosphorization and desulphurization. The increase in MnO content, however, may be effective for them by behaving as a basic oxide. Namely, the addition of manganese oxide increases phosphate capacity by increasing a_o^2- (N_MnO<0.12) and increases sulphide capacity by decreasing fs^2-. The slag, however, becomes partially solidified by excessive addition of manganese oxide (N_MnO>0.12) and dephosphorization reaction rate becomes slow. The optimum flux composition has been found as follows: CaO(30%)-CaF₂(15%)-MnO₂(1020%)-Fe₂O₃(3545%)