| 摘要 |
The invention is to implement an efficient dephosphorization treatment without adding a large amount of CaF2 and with a small addition amount of a refining agent. The invention is made based on the finding that a very efficient dephosphorization refinement utilizing an inhomogeneous molten state of slag can be implemented by feeding a gaseous oxygen and a refining agent onto a bath surface of a molten iron in a specific mode under conditions wherein a post-treatment slag is reduced appreciably in comparison to a conventional case. The dephosphorization treatment is performed by blowing the gaseous oxygen and at least a part of the refining agent onto the bath surface of the molten iron through a top blowing lance. Concurrently, the post-treatment slag rate is controlled to 30 kg/ton of molten iron or less, preferably to 20 kg/ton of molten iron or less, and more preferably 10 kg/ton of molten iron or less. In addition, the dephosphorization treatment be performed for an molten iron having a Si content of 0.15 mass% or less, more preferably 0.07 mass% or less, and particularly preferably 0.03 mass% or less. <IMAGE> |
