Dephosphorization of Liquid Iron by Na₂O-SiO₂ Slag

抄録

As one of the fundamental researches on the refining of molten iron by soda ash (Na₂CO₃), the experiments were made of dephosphorization of liquid iron by the sodium silicatetux containing Fe₂O₃ or Na₂CO₃, with various ratios of Na₂O and SiO₂ at the temperatures of 1550, 1600, and 1650°C.
The results o f these experiments indicated clearly the effects of the addition of Fe₂O₃, the slag basicity, the temperature, and the initial phosphorus content in liquid iron on dephosphorization by the slag of Na₂O-SiO₂ system, and the investigation also showed the refining actions of Na₂CO₃ in the flux.
Furthermore, a discussion was made on the equilibrium relationship of the dephosphorization reaction by Na₂O-SiO₂ Fe_tO slaps, and the following expression was obtained.
2P+5(Fe_tO)=(P₂O₅)+5Fe
logk_P=log {(%P₂O₅)/([%P]²•(%Fe_tO)⁵)}=8.67log(%Na₂O)-14.55 (1600°C)
From the comparison of the value of k_P obtained in this work with that for the CaO-based slag reported previously, it became clear that the Na₂O-based slag is more effective on dephosphorization than the CaO-based slag.