GB1160052A - Method for the Direct Reduction of Iron Oxides - Google Patents

Abstract

1,160,052. Gaseous reduction of iron ores. INSTITUT DE RECHERCHES DE LA SIDERURGIE FRANCAISE. Jan. 18, 1968 [Feb. 2, 1967], No. 2778/68. Heading C7D. In a multi-stage fluidized bed process for reducing pulverulent iron oxides by a gaseous mixture containing reducing gases e. g. H 2 and/or CO which maintains the oxides in suspension, (1) the oxide is introduced into a first reator maintained between 700 and 900‹ C. to reduce higher oxides to ferrous oxide by a gaseous mixture whose degree of oxidation (volume ratio of oxidized gases e. g CO 2 and/or H 2 O to total gases) is between OÀ1 and 0À5, (2) the ferrous oxide formed is introduced into a second reactor maintained between 400 and 600‹ C. and between 1 and 1À5 atmosphere pressure to at least partially reduce ferrous oxide to metallic iron by a gaseous mixture whose degree of oxidation is from 0 to 0‹1, (3) the product from the second reactor is passivated and cooled e.g. with cold N 2 containing 2-3% O 2 and the metallic iron magnetically separated e.g. by a magnetic drum from the ferrous oxide and gangue, and (4) either steps (2) and (3) are repeated on the separated ferrous oxide and gangue using a third reactor and further magnetic separator, or the ferrous oxide containing traces of magnetite is magnetically separated e. g. in a further drum from the gangue and recycled to the second reactor. The separated metallic iron may be treated in a further (fourth) reactor maintained between 700 and 900‹ C. and between 1 and 1‹5 atmosphere pressure to complete reduction of remaining ferrous oxide by a gaseous mixture whose degree of oxidation is from 0 to 0‹1, the product being further passivated and cooled. The gaseous mixture may be prepared by catalytic oxidation of CH 4 .