JPS5747807A - Simultaneous dephosphorization and desulfurization method for molten iron - Google Patents

Abstract

PURPOSE:To cause dephosphorization and desulfurization reaction efficiently and simultaneously by controlling the ratios of the total amount of oxygen and the amounts of dephosphorizing and desulfurizing agents and gaseous oxygen within a specific range in subjecting molten iron to simultaneous dephosphorization and desulfurization by blowing dephosphorizing and desulfurizing agents, a slag forming agent, an oxidizing agent, etc. together with gaseous oxygen into said molten iron. CONSTITUTION:With gaseous oxygen or air or the like contg. oxygen as a carrier gas, powder of desulfurizing and dephosphorizing agents such as CaO, Na2CO3 or the like, a slag forming agent such as CaF2 or CaCl2, and powder of a solid oxidizing agent such as scale or iron oxide are blown into the molten iron in a vessel by using an immersion lance. In this case, the total amount of oxygen to be blown (kg/min) is defined as A, the amount of the desulfurizing and dephosphorizing agents (kg/min) as B, and the amount of oxygen as a gas (kg/min) as C, and these are so controlled as contain A/B=0.2-0.7, C/A=0.03-0.30. The CaO-FeO type Na2O-FeO type low m.p. slag for dephosphorization reaction and the CaO single substance component for desulfurization are formed simultaneously, and the dephosphorization and desulfurization reaction progress simultaneously.