400t トーピードカーでのソーダ灰吹き込み脱りん処理中の諸現象

抄録

The new refining process which includes the desiliconization, dephosphorization and desulfurization was started at Kashima Steel Works in 1982. In this paper some phenomena during dephosphorization of hot metal by injection of soda ash in 400 t torpedo car are discussed. Followings are main results,
(1) The phosphorus partition (P₂O₅)/[P] is larger than 1 000 when the temperature is lower than 1 250°C and the basicity (Na₂O)/(SiO₂) is larger than 3.
(2) The vaporization of Na injected increases rapidly when phosphorus content becomes lower than 0.040%. But this vaporization is suppressed by increasing of (SiO₂) content in slag and injection rate of soda ash and O₂ blowing onto hot metal.
(3) It is effective for increasing of dephosphorization reaction and repressing of temperature drop of hot metal to blow oxygen onto hot metal during dephosphorization by soda ash.
(4) The loss of phosphorus and sulfer into the gas phase is less than 5% respectively.