METHOD AND DEVICE FOR PRODUCING CLEAN STEEL

摘要

PURPOSE:To produce a clean steel contg. O2, N2 and S at a low ratio by subjecting a raw metallic material to melting and primary refining by an induction furnace in a vacuum tank then subjecting the molten metal cast into a casting mold via a tundish to secondary refining again in the vacuum tank. CONSTITUTION:The raw material is melted in the induction furnace 4 in the vacuum tank 1. An inert gas is blown into the molten metal 25 by a lance 17 to stir the molten metal by which the O2 and N2 contained therein is removed. A desulfurizing agent is added to the molten metal to desulfurize the same. The slag in the furnace is heated by a heating coil 16 embedded in the upper part of the induction furnace by which the slag is made always fluid and is prevented from sticking to the lining. The molten metal 25 is poured into the tundish 8 when the furnace 4 is tilted. The molten metal is filtered with solid slag by the porous filter 23 of a nozzle 22 and is cast into the casting mold 9. The ingot stuck with the extremely little slag is again melted in the freshly lined induction furnace in the vacuum tank by which the dispersing and remaining pulverous slag is flocculated and removed. The clean steel contg. the impurities and slag at the low ratio is thus produced.