Patent ID: 9493854
Filing Date: 2016-11-15
CPC Classification: C21C,Y02P

Claim Text:
1. A converter steelmaking method of producing molten steel by supplying gaseous oxygen from a top blowing lance into a converter to perform decarburization refining of molten iron while adding a CaO-containing powdery dephosphorizing agent to simultaneously decarburize and dephosphorize the molten iron, comprising: joining the dephosphorizing agent and the gaseous oxygen together in the same lance; supplying the dephosphorizing agent to a bath surface of the molten iron together with at least one gas jet from the top blowing lance; and controlling a dynamic pressure determined from formulae (1)-(4) including an increasing amount of dynamic pressure due to a kinetic energy of the dephosphorizing agent when a gas jet including the gaseous oxygen accompanied by the dephosphorizing agent blown from respective lance nozzles of the top blowing lance impinges onto the bath surface of the molten iron to be not less than 0.10 kgf/cm wherein P: dynamic pressure at a center of the jet exerted on the bath surface of the molten iron by the gas jet blown from the lance nozzle [kgf/cm ρg: density of the gas jet [kg/Nm U de: outlet diameter of the lance nozzle [mm] P Lh: lance height [m] Fj: supply rate of the gas blown from the lance nozzle [Nm dt: throat diameter of the lance nozzle [mm] ρj: density of the gas blown from the lance nozzle [kg/Nm Vp: supply rate of the powdery dephosphorizing agent [kg/min].