| 摘要 |
<p>PURPOSE: To produce a high quality molten steel from molten iron and steel scrap by charging the molten iron, steel scrap and slag-making agent into a top/bottom blowing converter to execute phosphorization, decarburizing with oxygen blowing after discharging a large part of dephosphorized slag and desulfurizing under reducing condition in the furnace. CONSTITUTION: The molten iron and the steel scrap are charged into the molten slag of preceding charge remaining in the top/bottom blowing converter and N2 gas in blown from a tuyere in the furnace bottom so that stirring energy becomes 1.0kw/t to stir the molten iron, and the steel scrap is melted. Successively, basic flux of CaO, etc., and iron scrap as coolant are charged and the basicity of the molten slag is raised to 1.5-2.3 and molten iron temp. is made to the low temp. of 1300-1480 deg.C to remove P in the molten iron to 0.1-0.02%. After discharging >=75% of the dephosphorized slag by tilting the converter, the converter is straightly stood and the molten iron is decarburizingly refined by oxygen-blowing with the top-blowing lance and further, Al ash and CaO are added to dephosphorize the molten slag, and the molten iron is desulfurize-refined under the reducing slag. The molten steel dephosphorizingly, decarburizingly and desulfurizingly refined is tapped from the converter and raw material in the following heat is charged with the molten slag left behind to repeat the steelmaking refining.</p> |
