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■■■■■■■■■■■■■■■■■■■ 川崎製鉄技報 KAWASAKI STEEL GIHO Vol.4 (1970) No.1 ■■■■■■■■■■■■■■■■■■■ |
| 取鍋精錬炉の建設と操業経過 Construction of Ladle Refining Furnace (LRF) and Operational Experiences 西岡 武三郎(Takesaburo Nishioka) 江本 寛治(Kanzi Emoto) |
| 要旨 : 高級鍛錬用鋼塊および厚板向き鋼塊の製造を目的とした100t LRF（ASEA-SKFプロセス)は水島製鉄所電炉工場の第１期工事として建設され，1970年3月に稼働した。将来100ｔ電炉が建設されるまでは，母溶鋼は約３km離れた180t転炉から通常セミキルド鋼の状態で供給され，LRFで最高12％までの合金鉄が投入されて諸鋼種に転換される。1971年4月から30t電炉が稼働し，LRFを併用してEF-LRFも可能になった。標準操業は，加熱−脱ガスの２工程であるが，加熱と攪拌のみによって十分低酸素レベルが得られるので，脱水素を特に必要としない鋼種では脱ガス処理を省略できる。標準処理時間は，炭素鋼では1.5〜2hr，合金鋼では2〜3hrである。得られる製品の品質はすぐれており，安定度が高く，酸素レベルは10〜25ppm，脱ガス後の溶鋼中水素値は平均1.4ppm，脱窒率はセミキルド処理のとき10〜50％に達する。１年余の操業によって，この精錬法の優秀性が立証された。 |
| Synopsis : A ladle refining furnace (ASEA-SKF process) with a capacity of 100t/charge was completed and went into operation in March 1970 at Mizushima Works. This furnace had been under construction as part of the first construction plan of electric arc furnace shop with a purpose of producing high grade carbon steel and alloy steel for forging and heavy plates. In the LD-LRF process, mother metal is transported to LRF as semi-killed steel from the distant No.1 LD shop about 3km away, and is converted in LRF into steels of various grades by adding alloys up to 12% maximum. In April, 1971, a 30t electric arc furnace was started up and the EF-LRF process was put into practice. The standard practice consists of heating-degassing, but the degassing may be omitted in case the steel is of such grade that it is little affected by hydrogen, because a sufficiently low oxygen level can be attained only by heating and stirring. The refining of 100t takes 1.5 to 2h for carbon steel and 2 to 3h for alloy steel including 30min of degassing. All the steel product obtained by this process possess superior quality, free form variation. The oxygen level of the slab for heavy plates and forging ranges between 10 and 25ppm, and the hydrogen level in the molten steel after degassing is 1.4ppm on an average. Further, nitrogen is reduced to 40 to 50% of its initial content. The superiority of this refining process was not only confirmed by the actual experience from more than a year's operation, but has also been receiving good evaluation from users. This paper presents briefly some features of the subject plant, operational experiences, and the gas content of the steel thus obtained. |
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