Apparatus for reducing finely divided iron oxide material

Apparatus for reducing finely divided iron oxide material in a circulating fluidized bed, comprising a reactor (1) containing a vertical upper reaction chamber (2), downwardly connected to a lower, narrower, vertical reaction chamber (3), a cyclone separator (8) connected to the upper reaction chamber for separating the solid material from the circulating fluidized bed, a recycling conduit (9) from the cyclone separator to the reactor, nozzles (6) for supplying combustion air to the reactor, means (7) for supplying a reduction agent and an iron oxide material (18), means (11) for tapping off reduced material, and means (10) for supplying fluidizing gas to the lower reaction chamber, said recycling conduit (9) for the solid material opening into the bottom of the lower reaction chamber, said nozzles (6) for combustion air extending interiorly of an interior wall of the reactor at a distance which is at least equal to an inner diameter of the nozzles, and said means for tapping-off comprising a shaft (11) connected to the bottom of the lower reaction chamber (3), and of a lesser cross-sectional area than the lower reaction chamber and about less than 1/4 of the cross-sectional area thereof, said tapping-off means including a sluice (13) connected to said shaft for tapping-off the reduced material.