Abstract: Iron ore is efficiently reduced by entraining particles of the ore in a flow of heated reducing gas and passing the mixture through a constriction-expansion nozzle. Metallic iron is collected from the nozzle exhaust and conveyed to a suitable storage area. Passage of the iron ore and reducing gas composition through the nozzle results in the entrained ore being brought into intimate contact with the reducing gas, which contact promotes rapid reaction rates within the nozzle. The nozzle may comprise a Venturi constriction for producing up to sonic exhausts or, when enhanced reaction rates are desired, a converging-diverging nozzle for producing supersonic exhausts accompanied by associated shock wave patterns.