| 摘要 |
PURPOSE:To desulfurize and to dephosphorize cast iron with the same refining agent, by desulfurizing the desiliconized cast iron with a refining agent composed of CaO, CaCl2, KCl, etc., then by increasing the oxidizing power of the molten slag. CONSTITUTION:Molten cast iron is primarily desiliconized to 0.03-0.25% Si. Then 2-10kg refining agent composed of 1pts. wt. CaO, 0.2-0.5pts. wt. chloride, e.g., CaCl2 or KCl is added to 1 ton cast iron to form basic slag. The mixt. is agitated sufficiently by gas-bubbling to remove 70% of S contained in the molten cast iron into the above-described molten slag. Subsequently, an oxygen source such as oxygen gas, mill scale etc. is added so as to increase FeO content of the molten slag, and to oxidize P in the cast iron to P2O5. Hereby, S contained in the molten slag is oxidized and removed by the oxidation heat of Si contained in the molten cast iron, i.e., the cast iron is subjected to evaporation dusulfurization, preventing resulfurization which otherwise would be caused by the increase in acidity of the molten slag. P2O5 is fixed to the slag with CaO contained in the basic slag, thus the cast iron is dephosphorized. |
