DESILICONIZING, DEPHOSPHORIZING AND DESULFURIZING METHOD FOR MOLTEN IRON

摘要

PURPOSE:To simultaneously progress desulfurization and dephosphorization after desiliconization by coating a flux compounded with CaO and slag formability improving material on the surface of a molten iron from the initial period of a preliminary treatment for the molten iron and successively blowing a ferrous flux and alkaline flux thereto. CONSTITUTION:The flux essentially consisting of CaO and compounded with the slag formability improving material such as Mn ore is coated and imposed on the surface of the molten iron from the initial period of the preliminary treatment for the molten iron. The flux powder essentially consisting of iron oxide is blown by using a carrier gas simultaneously with top blowing of oxygen or addition of a solid oxygen source to execute the desiliconization treatment. The iron oxide flux is changed to the alkaline flux powder such as Na2CO3 for desulfurization and the supply of the oxygen is continued upon lapse of the desiliconization period to execute the desulfurization and dephosphorization reaction at the same instant. The entire stage of the desiliconization, desulfurization and dephosphorization is completed in a short period and the respective target values are attained with high accuracy by the above- mentioned method.