Method for direct reduction of iron bearing pellets or lump iron ore

A method for effecting direct reduction of iron oxides in the form of lumps or pellets, comprising passing an ore burden downwardly successively through prereduction and metallization zones of a shaft furnace while passing a flow of rich fuel gas produced by external partial combustion upwardly in counter current through the prereduction zone, and passing a flow of reducing gas in cocurrent though the metallization zone;

• wherein the flow of reducing gas is an independent flow that has not been subject to external combustion, wherein an intermediate zone is provided forming a narrowed throat between the prereduction and metallization zones, and wherein the reducing gas is at a boundary between the intermediate and metallization zones, whereby passage of rich fuel gas from the prereduction zone to the metallization zone is inhibited;
• wherein the reducing gas is a mixture of abut 20-25% natural gas, about 40% to 50% hydrogen, and about 20% to 30% carbon monoxide, balance being water vapour, carbon dioxide and nitrogen, preheated to about 700° C. to 950° C.;
• and
• wherein the carbon content of the reduced iron provided by the process is controlled by adjusting the natural gas content and temperature of the reducing gas, the natural gas content and the temperature being adjusted upwardly to increase carbon content, and the natural gas content and the temperature being decreased to decrease carbon content.