| 摘要 |
PROBLEM TO BE SOLVED: To satisfy both of quick discharge of slag in a slug-off step and a secondary blowing step sufficient in cost aspect and quality aspect in a refining method of molten iron where the molten iron is continuously subjected to a primary blowing step and a secondary blowing step with the slug-off step interposed therebetween by using one converter type refining furnace.SOLUTION: A refining method of molten iron includes: a primary blowing step of supplying a gaseous oxygen source from a top-blowing lance 2 to molten iron 5 in a converter type refining furnace 1 and applying oxidation refining to the molten iron 5; a slug-off step of discharging a part of slag produced in the primary blowing step; and, subsequently, a secondary blowing step of adding CaO-based flux thereto, supplying the gaseous oxygen source thereto and applying the oxidation refining to the molten iron 5 remaining behind. A slag height in the converter type refining furnace 1 is measured during the primary blowing step, blowing is performed until a ratio of the slag height to an in-furnace free board height is equal to 0.6 or more, inputting slag-foaming depressant into the converter type refining furnace 1 and the blowing is continued when the ratio of the slag height thereto is equal to 0.6 or more and less than 0.8, and the primary blowing step is completed in a state of the ratio of the slag height thereto being equal to 0.5 or more and equal to 0.7 or less.SELECTED DRAWING: Figure 2 |
