Process for producing molten pig iron with melting cyclone

A process for producing molten pig iron by direct reduction of iron ore in a pre-reduction stage followed by a final reduction stage which forms a reducing process gas, comprising the steps of

• (a) conveying iron ore into a melting cyclone and pre-reducing the iron ore in the pre-reduction stage by means of the reducing process gas formed in said final reduction stage;
• said reducing gas being directly fed into the melting cyclone from the metallurgical vessel situated beneath the melting cyclone,
• (b) effecting a post-combustion in said reducing process gas in said melting cyclone by supplying substantially pure oxygen thereto so that said iron ore in said melting cyclone is at least partly melted,
• (c) permitting the pre-reduced and at least partly melted iron ore to pass downwardly from said melting cyclone into the metallurgical vessel in which said final reduction takes place, and
• (d) effecting said final reduction in said metallurgical vessel in a slag layer therein by supplying coal and oxygen to said metallurgical vessel and thereby forming the reducing process gas, and effecting a partial post-combustion in said reducing process gas in said metallurgical vessel by means of said substantially pure oxygen supplied thereto, said coal being supplied directly into said slag layer,
• (e) wherein the post-combustion ratio defined as ##EQU3## in which CO.sub.2, CO, H.sub.2 O and H.sub.2 are the concentrations in percent by volume of these gases on exiting said metallurgical vessel, is not more than 0.55, and
• (f) wherein said partial post-combustion in said metallurgical vessel at least partly occurs in said slag layer.