REFINING METHOD

To stably discharge a large amount of slag in intermediate deslagging in refining of molten metal in a converter type vessel.SOLUTION: The inventive refining method includes a first step for subjecting molten iron to at least an Si removal treatment, a second step for storing the molten metal having undergone the first step and slag in a converter type vessel and adjusting an amount of slag to be in a predetermined range, a third step for spraying acid into the converter type vessel to subject the molten metal to a P removal treatment, foaming the slag, a fourth step for performing intermediate deslagging to discharge slag out of the throat of the converter type vessel, and a fifth step for adding flux into the converter type vessel after intermediate deslagging, to subject the molten metal to a C removal treatment. At the finish of the first step, an Si content of the molten metal is 0.28 mass% or less. At the time when acid spraying is stopped in the third step, the slag has a basicity of 0.8-1.5. In the third step, a height of foaming is measured. At the time when acid spraying is stopped before intermediate deslagging, the height of foaming satisfies a formula (1).SELECTED DRAWING: Figure 3 【課題】転炉型容器における溶湯の精錬処理により生成したスラグを中間排滓する際に、安定して多量のスラグを排出すること。【解決手段】本発明に係る精錬方法は、溶銑に少なくとも脱Ｓｉ処理を施す第１工程と、第１工程を経た溶湯とスラグを転炉型容器に貯蔵し、スラグの量を所定範囲に調整する第２工程と、転炉型容器内に吹酸することで、溶湯に対して脱Ｐ処理を施し、スラグをフォーミングさせる第３工程と、スラグを炉口から排滓する中間排滓を実施する第４工程と、中間排滓後の転炉型容器内にフラックスを添加して、溶湯に対して脱Ｃ処理を施す第５工程を含む。第１工程の終了時における溶湯のＳｉ濃度は、０．２８質量％以下であり、第３工程の吹酸停止時におけるスラグについて、塩基度を０．８～１．５とし、第３工程では、フォーミングの高さを測定しておき、中間排滓前の吹酸の停止時におけるフォーミングの高さが、式（１）を満足する。【選択図】図３