The Dephosphorization Steelmaking Furnace* of Hot Metal outside the By Takami IKEDA* * and Tohru MATSUO** Synopsis

The preliminary dephosphorization method of hot metal outside the steelmaking furnace was investigated to obtain extra low phosphorus steels and to utilize the LD slag. Hot metal with the phosphorus content of 0.09- 0.16 % was treated in a ladle with the dephosphorization agent consisting of LD slag and iron oxide or lime and iron oxide, and the phosphorus content of hot metal was reduced to 0.020 (9.060 % or 0.003 0.020 %, respectively. By refining the dephosphorized hot metal in LD converter, extra low phosphorus killed steels having the phosphorus content oflower than 0.005 % were obtained. By applying this dephosphorization method for the production of normal phosphorus steels, the amount of generated LD slag is decreased, and the LD slag can be utilized mainly as a dephosphorizing agent of hot metal again. I