PROCESS FOR THE REDUCTION OF FINELY DIVIDED METAL OXIDE-CONTAINING MATERIAL

摘要

1521499 Direct reduction of ores STORA KOPPARBERGS BERGSLAGS AB 11 Dec 1975 [12 Dec 1974] 50795/75 Heading C7D In the reduction of finely-divided metallic oxide material (e.g. Fe or Ni oxides) with carbonaceous material in a reactor supplied with a gas containing 02 (e.g. air), at least part the off-gas mixture containing CO, CO 2 , H 2 , H 2 O is treated with water (preferably as super-heated steam) to react with CO to form CO 2 and H 2 , whereupon the CO 2 is removed and the gas recycled to the reactor for reduction purposes. The oxide may be iron ore concentrate or calcined pyrites, and the carbonaceous material coke, coal, or anthracite, at least part of which may be replaced by oil. The reactor is preferably a fluidized bed, but may be a rotary furnace. In reaction chamber 1, solids are charged at 6, air at 7, and fluidizing gas at 8, and the metallized product is removed at 11. Gas is separated from the particles in cyclones 2, 3 and exits through pipes 9, 10. The gas in pipe 9 is returned directly to the reactor. Gas from pipe 10 is treated with steam at 12 and iron oxide and/or carbonaceous material and/or Fe-containing material at 13 and passed to cyclone 16 where the solids pass to the reactor 1 and the gas to heat exchanger 19, the gas flow 18 then passing to C02 scrubber 20 (using K 2 CO 3 ) and cooler 27 (for H 2 O removal) prior to returning through exchanger 19 and combining with flow 9 to form the fluidizing gas 8. In another embodiment, Fig. 2 (not shown) there is only one cyclone 2 and one gas conduit 9, the offgas being divided into a portion (33) which is returned directly to the reactor and the remainder (34) passes to a bed (36) of catalyst material (e.g. Cr-Fe) where the H 2 O/CO reaction occurs with steam, the gas flow (37) then treated as flow 18. Typically, 30-70% of the off-gas may be so treated. If desired, all of the off-gas may be treated by combining conduits 9 and 10 in Fig. 1 or by removing conduit (33) in (Fig. 2). The carbonaceous material may be coke breeze, coal breeze or anthracite breeze.