Innovative Development of Refining Processes in Steelmaking by Using Multi-phase Fluxes 'Mechanism of Dephosphorization by Using Multi-phase Flux'

摘要

The microscopic reaction mechanisms between solid CaO and liquid FeOx-CaO-SiO2-P2O5 slag should be clarified to understand the dephosphorization behavior by using the multi-phase flux that means the solid and liquid coexisting flux at hot metal dephosphorization temperature. In the present study, solid CaO or 2CaO.SiO2 and liquid FeOx-CaO-SiO2-P2O5 slag were reacted at 1573 and 1673 K, and the interface between solid piece and molten slag was observed and analyzed by SEM with EDS. In the case of CaO dipping experiment, the CaO-FeOx phase was observed adjacent to solid CaO, and 2CaO.SiO2 phase surrounded by liquid FeOx-CaO-SiO2 with high FeOx content was formed next to the CaO-FeOx layer. The reaction mechanisms between solid CaO and molten slag are discussed based on the estimated activities of FeO and CaO in each phase. On the contrary, P2O5 in slag was condensed in the 2CaO.SiO2 at the interface between dipped 2CaO.SiO2 and slag. However, P2O5 content in the condensed phase was not large compared to that observed after CaO dipping, neither was the amount of condensed phase.