| 摘要 |
PURPOSE:To control the generated amount or the splash height above the surface of steel bath at a low level, by a method wherein the mixture of O2 and inert gas is blown into from the lower surface of molten bath and further O2 is blown into by controlling the height or/and the O2 amount of top-blown lance depending on the transition of C amount in molten bath. CONSTITUTION:In decarburizing the carbon in molten steel 4 containing chromium with a refining vessel 10, the mixed gas of inert gas and O2 are bottom-blown from a tuyere 11 and O2 14 is top-blown from a top-blown lance 12 together therewith. In that case, the molten steel is refined by controlling both on either of the lance height from the molten steel surface of lance 12 and the top-blown O2 amount depending upon the transition of the C amount in molten steel containing chromium, that is, the proceeding degree of decarburization reaction in molten steel containing chromium. That is, the splash generated from the surface of molten bath in refining above-mentioned, the splash due to bottom-blow is effectively controlled by adjusting the height of lance 12 or/and the top-blown amount. Thus, by raising the O2 blow amount without enlarging the vessel volume compared with the molten steel amount, the decarburization speed is accelerated and simultaneously the heat of formation in decarburizing reaction according to the blow-in of O2 can be effectively utilized. |
