含炭塊成鉱を用いた高炉の還元材比低減技術

摘要

Increasing coke gasification rate can lowers the temperature of the thermal reserve zone, resulting in a decrease of carbon consumption and a reduction of the reducing agent rate of blast furnaces. To achieve this increase, the enhancement of coke reactivity itself or the close arrangement of iron ore and carbonaceous materials has been investigated in Japan. Against this, RCA, "Reactive Coke Agglomerate," having a high carbon content, has been developed, and it was found that the agglomerate mixed-in sinter layer had two functions: one having high reducibil-ity itself and the other enhancing the reduction of the surrounding sinter. As a result of the two functions, a significant decrease of the temperature of the thermal reserve zone and an increase of gas utilization by using the agglomerate mixed-in sinter layer in a BIS test was achieved. As for the strength after reaction, disintegration was fairly small in comparison with that of the sinter both in the laboratory scale test and in a basket test using a plant's vertical probe. Long-term plant trials have been conducted at the Oita Works No.2 Blast Furnace with a maximum use of 54 kg/tHM. It was found that RCA could lower the temperature of the thermal reserve zone and carbon consumption in a commercial blast furnace. Carbon consumption was decreased along the relationship of 0.36 kgC/tHM per 1 kgC/tHM of input carbon from RCA.%近年の鉄鉱石と石炭の価格高騰，良質資源の枯渴化により，天然資源に乏しい我が国の鉄鋼業は銑鉄製造コストの更なる上昇に加え，使用難易度の高い劣質原料利用を余儀なくされている。このような背景の下，我が国の鉄鋼メーカーが国際的競争力を維持し，トップランナーとして世界の鉄鋼業を牽引していくためには，現状の原料事情を踏まえた資源戦略強化に加え，高度で先進的な銑鉄製造技術を開発していく必要がある。