METHOD FOR REFINING MOLTEN IRON

• Main Authors: MOMOSAKI KAZUHITO, MAEDA TAKAHIKO, OGASAWARA YASUSHI, MORI MIKIHIRO, ITO TOMOHIKO, OKUYAMA GORO, MIKI YUJI
• Format: Patent
• Language: English; Japanese
• Published: 03.08.2017
• Subjects: CHEMISTRY; METALLURGY; METALLURGY OF IRON; PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OFWROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS

PROBLEM TO BE SOLVED: To suppress slag forming in a slag pod and discharge the targeted predetermined amount of in-furnace slag in short time quickly in an intermediate slag removing process between a plurality of refining processes which are conducted on molten iron accommodated in one converter type refining furnace with oxygen supplied.SOLUTION: In a method for refining molten iron 5 discharging a part of a slag 6 in an intermediate slag removing process between refining processes divided into plural ones, refining conducted before the intermediate slag removing process is completed when a slag height ratio is 0.3 or more and less than 0.6, where the slag height ratio is a ratio of slag height measured from a molten iron bath surface in a furnace before the intermediate slag removing process to height of a free board in the furnace from the molten iron bath surface in the furnace to a throat of the furnace, the molten iron is maintained for 1.0 minute or more to 5.0 minutes or less blowing a bottom blow gas and discharge of the slag is initiated when the slag height ratio is 0.3 or more and less than 0.6.SELECTED DRAWING: Figure 2 【課題】 酸素を供給して行う複数の精錬工程を、１つの転炉型精錬炉に収容された溶銑に施すにあたり、上記複数の精錬工程の間の中間排滓工程において、スラグポット内でのスラグのフォーミングを抑制しつつ、目標とする所定量の炉内スラグを速やかに短時間で炉外に排出する。【解決手段】 複数に分割された精錬工程の間の中間排滓工程で、スラグ６の一部を排出する溶銑５の精錬方法において、中間排滓工程よりも以前に、炉内の溶銑浴面からのスラグ高さを測定し、炉内の溶銑浴面から炉口までの炉内フリーボードの高さに対する測定されたスラグ高さの比率をスラグ高さ比率と定義したとき、スラグ高さ比率が０．３以上０．６未満のときに中間排滓工程の前に行う精錬を終了し、その後、底吹きガスを吹き込みながら１．０分間以上５．０分間以下保持し、次いで、スラグ高さ比率が０．３以上０．６未満のときにスラグの排出を開始する。【選択図】 図２