FIELD: metallurgy. SUBSTANCE: double-stage furnace with fluidized bed for preliminarily reducing finely divided iron ore includes first stage furnace for receiving finely divided iron ore from hopper, discharging ore with mean/small size particles to upper portion of furnace and reducing large particle ore at providing bubbling fluidized bed; second-stage furnace for receiving mean/small particles discharged from upper portion of first-stage furnace for reducing them at forming turbulent fluidized bed; first high temperature cyclone for trapping small particles containing in gas leaving second-stage furnace. First stage-furnace has narrow upper portion, wide lower portion and intermediate inclined portion. Second stage furnace has wide upper portion, inclined portion and narrow lower portion. In first stage furnace iron ore is separated by fractions with large particle more than 0.5 mm and mean/small particle less than 0.5 mm. Effective rate of fluidizing in lower portion of first-stage furnace is equal to 2.0-2.5 m/s, in lower portion of second-stage furnace 0.2-0.5 m/s. EFFECT: improved design of furnace allowing to reduce iron ore with wide range of particle size and large quantity of small size particles. 10 cl, 3 dwg, 1 ex
