Process for the direct reduction of iron oxide-containing materials with solid carbonaceous reducing agents

摘要

Materials containing iron oxide are reduced in a first expanded fluidised bed using solid carbon-containing reducing agents (reductants) under weakly reducing conditions at most to the FeO state. The gas/solid suspension discharged is treated in a second expanded fluidised bed with strongly reducing fluidising gas, with the material being partially reduced to metallic iron. The carbonised carbon-containing material is separated from the gas/solid suspension discharged and is recirculated to the first fluidised bed. A part of the strongly reducing gas is, after purification and removal of CO2, recirculated to the second fluidised bed as fluidising gas. A reduced material having a degree of metallisation of from 50 to 80% together with the remaining part of the carbonised carbon-containing material is discharged from the lower part of the second fluidised bed and is completely reduced and melted in a fusion reactor. The gas evolved from the melt is partially further burnt directly above the melt by blowing-on of oxygen-containing gases and the heat thus generated is largely transferred to the melt. A complete further combustion of the gas is carried out in a subsequent second further combustion (afterburning) process. The material discharged from the lower part of the second fluidised bed can be further reduced in a third fluidised bed to a degree of metallisation of up to 95%.