| 摘要 |
<p>PURPOSE:To increase the temp. of molten iron by decarbonization and to increase the blending ratio of scrap iron by using molten iron which is previously desiliconized, dephosphorized, and desulfurized as an iron source, using essentially bottom blowing of oxygen, and forming a dent in an appropriate depth on the surface of molten iron by top blowing of oxygen in steel making. CONSTITUTION:A bottom blowing oxygen tuyere 3 is provided to a vessel obtained by lining an iron shell 1 with a refractory material 2, and a top blowing oxygen lance 4 is provided to a top and bottom-blown oxygen steel making furnace. Molten pig 5 which is previously desiliconized, dephosphorized, and desulfurized is used as an essential iron source, and the decarbonization is carried out essentially by bottom blowing of oxygen in the top and bottom-blown steel making process. In said steel making process, the flow rate of the top-blown oxygen is regulated to <=60% of the flow rate of the bottom-blown oxygen, and the depth of a dent 6 formed on the surface of a molten iron bath by top blowing of oxygen is regulated to 20-200mm.. Secondary combustion of carbon is promoted, and the temp. of the molten iron is increased by the decarbonization in this way. Accordingly, the blending ratio of scrap iron as the principal material for steel making can be increased, and the mixing ratio of molten iron can be decreased.</p> |
