METHOD FOR RAISING TEMPERATURE OF MOLTEN IRON

PURPOSE:To prevent the lowering of temp. of molten iron in a pretreatment by blowing oxygen into the molten iron from a top-blowing lance, adding aluminum ash and simultaneously blowing pretreating agent into the molten iron at the time of pretreating the molten iron. CONSTITUTION:At the time of producing molten steel by transporting the molten iron tapped from a blast furnace to a converter to execute decarburization-refining, the pre-refining such as desiliconizing, dephosphorizing, desulfurizing are executed to the molten iron, thereafter the only decarburization-refining is executed in the converter to improve the steelmaking refining efficiency. Since the molten iron temp. is lowered by adding the pretreating agent in the pre-refining treatment to cause the lowering of the yield of the molten steel and the lowering of the productivity at the time of decarburization-refining in the converter, in order to keep the molten iron temp. at the high temp. at the time of charging it into the converter, the molten iron is charged into a vessel of a torpedo car, etc., and the oxygen is blown onto the surface of the molten iron from the top-blowing lance and also, the aluminum ash is added at the time of pre-refining the molten iron. Simultaneously, the pretreating agent such as desiliconizing agent, dephosphorizing agent is blown from the other injection lance. The temp. of the molten iron lowered by adding the pretreating agent, is supplemented with the oxidizing heat of the aluminum in the aluminum ash to raise the temp. to the temp. being suitable to the decarburizationrefining.