Abstract: Apparatus for reducing finely divided iron oxide material, comprising a reactor containing a vertical upper reaction chamber connected downwardly to a narrower, vertical reaction chamber. A cyclone separator is connected to the upper reaction chamber for separating solid material and recycling it to the reactor so that a circulating fluidized bed can be maintained in the apparatus. In accordance with the invention, a recycling conduit is connected to the bottom of the lower reaction chamber. A tapping-off shaft for reduced material is also connected to the bottom of the lower reaction chamber. A reducing agent is supplied to the upper reaction chamber, and combustion air is supplied to the bottom of the upper reaction chamber. The apparatus also comprises means for preheating the iron oxide material with the exhaust gas from the reactor and for passing said preheated iron oxide into the lower reaction chamber. The apparatus also comprises means for stripping the exhaust gas from CO.sub.2 and H.sub.

Abstract: Carbonaceous material, preferably coal or like finely divided solids with a mean particle diameter of 30 to 250 microns, is burned to produce steam in a fluid-bed furnace having a lower free space without internal fixtures and provided above this free space with internal cooling surfaces. A secondary-gas inlet introduces the secondary gas so that the volume ratio of fluidizing gas to secondary gas ranges from 1:20 to 2:1 at a location above the fluidizing-gas and fuel inlets but below the internal cooling surfaces, the gas velocity of the several gases being adjusted so that the mean suspension density of the solids above the secondary-gas inlet is 15 to 100 kg/m.sup.3. Approximately stoidiometric conditions are maintained with respect to the oxygen in the gases introduced and the carbonaceous material and solids are recycled to the bed after being separated from the gases emanating therefrom.

Abstract: A method of reducing a pulverized material containing iron oxides mixed with carbonaceous material wherein: (a) a circulating fluidized bed is maintained in a vertically elongated reaction zone by supplying it with suitable quantities of pulverized material containing iron oxides, pulverized solid carbonaceous material and optionally liquid carbonaceous material, and gas containing molecular oxygen and that gas and solid material leaving the reaction zone are separated, the solid material being returned to the reaction zone; (b) the pulverized material containing iron oxides, the carbonaceous material and the gas containing molecular oxygen are supplied to an intermediate section of the reaction zone; (c) the flow of carbonaceous material fed to the bed is controlled so that there is always sufficient coke in the bed to prevent interference of the fluidization caused by sticking or agglomeration; (d) gas and solid material leaving the reaction zone are extracted from the upper part of the reaction zone, the s