Abstract
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 ao2- (NMnO<0.12) and increases sulphide capacity by decreasing fs2-. The slag, however, becomes partially solidified by excessive addition of manganese oxide (NMnO>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%)
