Dust Recycling System by the Rotary Hearth Furnace

Dust recycling technology by the rotary hearth furnace has been applied at Nippon Steel’s Kimitsu Works since 2000. The dust and sludge with iron oxide and carbon are agglomerated into shaped articles and the iron oxide is reduced in a high temperature atmosphere. Zinc and other impurities in the dust and sludge are expelled and exhausted into off gas. The DRI pellets made from the dust and sludge have 70% metallization and are strong enough for being recycled to the blast furnaces. No. 1 plant, which was constructed in May 2000 and has an agglomeration method of pelletizing, recycles mainly dry dusts. No. 2 plant, which was constructed in December 2002 and has an agglomeration method of extrusion, does mainly sludge. The combination of the two plants is a solution for recycling variety kinds of dusts and sludge emitted in an large scale steel works as Kimitsu Works.