DEPHOSPHORIZING AGENT AND DEPHOSPHORIZING METHOD EXCELLENT IN MOLTEN IRON DEPHOSPHORIZING PERFORMANCE

摘要

PROBLEM TO BE SOLVED: To efficiently dephosphrize a molten iron without using fluorite by maintaining the weight ratio of quick lime to iron oxide and/or gaseous oxygen in terms of oxygen to be a specified value for higher slag property of quick lime. ;SOLUTION: The weight ratio of quick lime in a dephosphorizing agent containing no fluorite to iron oxide and/or gaseous oxygen in terms of oxygen, i.e., CaO/O is 0.2 to 0.7. Mixture of quick lime powder with iron oxide powder and gaseous oxygen are uniformly mixed and injected in a molten iron. For example, the temperature of the molten iron is 1350°C, and the composition of the molten iron is 4.1-4.5% C, 0.05-0.40% Si, 0.21-0.43% Mn, 0.07-0.150% P and 0.020-0.030% S. When dephosphrization is promoted by blending fluorite and SiO2 in the dephosphorizing agent, ≤3% fluorite is preferably added, and ≤10% SiO2 is preferably added. The dephosphirizing agent can be injected by either a nozzle of an immersion lance, a bottom-blow nozzle or a side-blown nozzle.;COPYRIGHT: (C)2000,JPO