FIELD: ferrous metallurgy. SUBSTANCE: assembly comprises in-series connected furnace for drying and preheating with first cyclone coupled with it; primary furnace for preliminary reduction with second cyclone coupled with it; secondary reduction furnace with high-velocity gas stream for finally reducing only part of preliminarily reduced iron ore with coarse particles in fluidized state while simultaneously withdrawing part of iron ore with middle and fine particles; secondary reduction furnace with low-velocity gas stream for finally reducing iron ore with middle and fine particles to form fluidized bed; internal cyclone located in secondary reduction furnace with low-velocity gas stream; and third cyclone to catch dustlike iron ore not caught by internal cyclone. Furnace for drying and preheating and furnaces for preliminary and final reduction with low-velocity gas stream are executed with variable diameters along their heights. Height of each bottom part of these furnaces is 7-12 times larger than their internal diameter, and height of their top parts 2-4-fold exceeds corresponding internal diameter. Height of furnaces with high- velocity gas stream 20-30 times larger than their internal diameter. EFFECT: increased utilization of gas and extent of hydrogenation due to shortened iron ore residence time and increased degree of preliminary iron ore hydrogenation. 18 cl
