| 摘要 |
PURPOSE:To simply and efficiently pretreat molten iron by executing suitable bottom blowing at the time of injecting desulfurizing flux after dephosphorized- treating the molten iron by top-blowing oxygen and bottom-blowing inert gas in a pretreating furnace. CONSTITUTION:To the molten iron 5 accomodated in the pretreating furnace 1 having the bottom-blowing tuyeres 2, while blowing the inert gas of gaseous N2, etc., from the bottom-blowing tuyere 2, dephosphorizing treatment is execut ed by blowing the gaseous oxygen for refining from the top-blowing lance 3. After that, immediately, the oxygen blowing for refining is stopped and by blowing the inert gas from the above furnace bottom tuyere 2 at 0.01-0.07Nm<3>/ min.t, the molten iron 5 is stirred. Together with this, desulfurizing flux of Na2CO3 series, etc., is injected into the molten iron 5 from the injection lance 4 submerged in the molten iron 5, to execute the desulfurizing treatment. By increasing this stirring force, the desulfurizing efficiency is improved. In this way, the pretreatment for dephosphorizing and desulfurizing can be treated in the one vessel in a short time.
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