| 摘要 |
<p>PURPOSE:To efficiently refine a low P, S molten steel in a short period of time by adding Al through an immersion pipe to the in-ladle molten steel of an adequate temp. tapped after converter refining is blown out at a cryogenic temp. and subjecting this molten steel to oxygen blowing and heating up, then to desulfurization. CONSTITUTION:High P and S raw materials contg. low-grade steel scrap, etc., are charged into a converter and a slag forming material such as lime is added thereto, then oxygen blowing is executed. This converter refining is blown out at the cryogenic temp. to accelerate the dephosphorization reaction. The molten steel subjected to the dephosphorization is tapped from the converter into the ladle and the temp. of the molten steel in the ladle is set higher by 10-40 deg.C than the liquid phase temp. (LL) of the molten steel. The immersion pipe is then inserted into the in-ladle molten steel. Oxygen is blown to the molten steel from a lance while metal or alloy of Al is added thereto through this immersion pipe. The reaction to form Al2O3 is thereby efficiency effected and the molten steel is heated up in a short period of time by the reaction heat thereof. A flux contg. a desulfurizing agent such as quicklime is added to this molten steel and an inert gas is blown thereto to stir the molten steel. The desulfurization reaction is efficiently accelerated by the above-mentioned Al2O3 and the smelting of the low P, S molten steel is executed.</p> |
