| 摘要 |
PURPOSE:To obtain low phosphorus and high carbon steel of improved dephosphorization efficiency by forming the slag of low basicity in the initial period of blowing of low phosphorus iron after a dephosphorization treatment then adding CaO to increase the basicity of slag thereby reducing the forming time for slag and improving a P2O5 setting function in the final. CONSTITUTION:In the initial period of blowing in the stage of producing high carbon steel by blowing the low phosphorus iron obtained beforehand by a dephosphorization treatment, CaO and Si sources are added so as to form slag of low m.p. and low basicity, that is, CaO/SiO2=1.0-2.0 for the purpose of accelerating slag formation. If a small amt. of a fluxing agent such as CaF2 is used in combination, a slag forming property is accelerated further. When the slag formation progresses and the improvement in dephosphorization rate ceases, amt. of CaO that makes the basicity of the formed slag 3.0-4.0 is added to obtain the low phosphorus and high carbon steel. If the CaO is added when the molten steel temp. is >=1,800 deg.C, the formation of the high basicity slag is easy, and the reduction in the dephosphorization time is made possible. |
