| 摘要 |
PURPOSE:To improve desulfurization efficiency and to prevent the decrease of the carbon content in a molten iron by using Ca(OH)2 as a desulfurizing agent, CaO and CaF2 as a slag formation accelerator in the stage of subjecting the molten iron to preliminary desulfurizing and refining. CONSTITUTION:The molten iron is subjected to desiliconization, desulfurization and dephosphorization refining prior to refining by a converter as preliminary refining on the outside of the converter in the stage of producing a molten steel by oxygen blowing of the molten iron in the converter. 5-80% Ca(OH)2 which forms CaO having excellent activity by thermal decomposition as the desulfurizing agent to be used for the desulfurization refining, 10-90% CaO and flux mixed with CaF2 at a 1-10% ratio as the slag formation accelerator are used. A reduction reactive material such as C or Al is otherwise added thereto in order to improve the desulfurization effect. The oxygen potential in the molten iron is decreased by said material, by which the reducing characteristic necessary for the desulfurization reaction is enhanced and the desulfurization effect is improved. The decrease of the carbon content in the molten steel as in the case of using CaCO3 is obviated and the need for replenishing C as a heat source in the stage of blowing in the converter or the like is eliminated.
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