| 摘要 |
<p>PURPOSE:To obtain a molten steel having high quality suitable for production of a cold rolled steel sheet by carburizing and melting scrap, mixing the same with a blast furnace molten iron at the compounding ratio adjusted according to the components of the scrap and subjecting the mixture to oxygen blowing in the stage of decreasing impurity elements which are difficult to be removed by blowing. CONSTITUTION:The scrap preheated in a preheating furnace 1 is carburized and melted in a carburization melting furnace 2 and is made to the pseudo molten iron 3 having about 1,300 deg.C temp. and >=3% carbon concn. The molten iron 3 is subjected to component analysis 4 and the compounding ratio with the blast furnace molten iron 5 is determined according to the analyzed values thereof, then both molten irons 3, 5 are mixed to form a molten iron mixture 6. The molten iron mixture 6 contains >=3.0% C and contains elements such as Ni, Cu and Cr which cannot be reduced by the oxygen blowing in a converter 7 at a low value as these elements are diluted. The molten iron mixture 6 is then subjected to the oxygen blowing in the converter 7 by a conventional practice, by which the C, Si, S, P, N, etc. are reduced to the prescribed value and the molten iron is held at the prescribed temp. The molten steel is tapped in such a state and the molten steel 8 having the high quality suitable for production of the cold rolled steel sheet is obtd.</p> |
