On the Simultaneous Dephosphorization and Desulfurization of CarbonSaturated Iron by Sodium Carbonate and Sodium Sulfate Flux

Abstract

The effect of the temperature, silicon and manganese in carbon-saturated iron (0.1% P, 0.05% S) on the dephosphorization and the desulfurization was studied by the use of the 2Na₂CO₃-Na₂SO₄ flux. The degree of the dephosphorization and the desulfurization considerably decreased and the evaporation of sodium increased with increasing temperature. As a result of the flux consumption for the oxidation of silicon, their degree was found to remarkably decrease, but manganese in metal was found to gradually decrease. The reversion of phosphorus and sulfur was observed after the end of the flux addition, but the extent of their reversion decreased when silica was present in the flux.
The behavior of the dephosphorization and the desulfurization obtained by the 2Na₂CO₃·Na₂SO₄ flux was compared with those by the Na₂CO₃ flux and the 2Na₂CO₃·Fe₂O₃ flux. The degree of the dephosphorization was almost same, but the remarkable evaporation of phosphorus was observed according to the acceleration of CO formation by the reduction of iron oxide with carbon in metal. This evaporation was also observed in the 2Na₂CO₃·Na₂SO₄ flux, but its extent decreased with increasing the P₂O₅ and the SiO₂ concentration in slag.