Process for the direct reduction of materials containing iron oxides

摘要

The present invention describes a process for the direct reduction of materials containing iron oxides in fluidised beds with circulation of reduction gas, wherein a) the materials containing iron oxides are charged into a circulating fluidised bed, hot reduction gas is passed in as fluidising gas, the suspension discharged from the fluidised-bed reactor is substantially freed of solid in a recirculation cyclone and the solid separated off is returned to the fluidised-bed reactor, b) solid is introduced into a classical fluidised bed, hot reduction gas is passed in as fluidising gas, the residual oxygen is reacted and the iron content is converted to the extent of < 50% into Fe3C and the product is taken off, c) a substream of the off-gas is conducted away according to (a), and, after enrichment by addition of reducing gas and heating as circulation gas, the remaining substream of the off-gas is passed according to (a) partly as fluidising gas into the fluidised bed according to (a) and partly into the fluidised bed according to (b).