Abstract

Lepinski, J.A. (Midrex Direct Reduction Corp.). Direct reduction is the process of converting iron ore into metallic iron without melting. Direct reduced iron (DRI) is used as a high quality feed material in electric arc furnace steelmaking, oxygen steelmaking, ladle metallurgy, blast furnace ironmaking, and foundries. Normally 90 to 95% of the iron in DRI is in the metallic form. Carbon is normally present in the DRI to balance any remaining iron oxide, and the level of residual elements is very low. The reduction of iron oxide proceeds from hematite to magnetite to wustite to iron. Some of the iron may combine with carbon to form cementite; DRI having high percentages of cementite is sometimes called iron carbide. The most common reductants are reformed natural gas and coal. The main commercially proven direct reduction processes are discussed. Hot briquetted iron (HBI), a densified form of DRI, is more resistant to reoxidation and corrosion. Vol. 14, pp. 855–872, 7 refs. to April 1994.