Coke breeze-less sintering of BOF dust and its capability of dezincing

Abstract

In order to promote recycling of basic oxygen furnace (BOF) dust, sintering of the dust without coke breeze (fuel) has been researched by pot test method and the possibility of dezincing during the sintering has been evaluated. Typical BOF dust, containing about 20% of metallic iron (M.Fe), is agglomerated without fuel and dezinced by about 50% during sintering. The agglomeration is caused by heat generation due to oxidation of the metallic iron. The dezincing takes place by the reaction: ZnO+M.Fe→Zn(gas)+FeO at elevated temperature. Secondary dust emitted during sintering mainly consisted of ZnO containing 40 to 50% of zinc. The ratio of dezincing is improved by blast furnace (BF) dust addition and up-draft sintering method. The carbon in BF dust produces metallic iron and CO gas from `FeO' melt, then they accelerate ZnO reduction. The up-drafting makes a melt pool in the lower layer, where the melt remains longer at high temperature, resulting in increase in the ratio of dezincing.