Methods and systems for increasing the carbon content of sponge iron in a reduction furnace

A system for producing direct reduced iron having increased carbon content, comprising:

• a direct reduction furnace for partially or completely reducing iron oxide to form partially or completely reduced iron oxide;
• a reformer for providing a reformed gas stream;
• a conduit for delivering the reformed gas stream to a carbon monoxide recovery unit to form a carbon monoxide-rich gas stream and a hydrogen-rich gas stream;
• a conduit for delivering a hydrocarbon-rich gas stream to a mixer, where it mixes with the carbon-monoxide-rich gas stream;
• a preheater disposed between the mixer and the direct reduction furnace for preheating the mixture of the carbon monoxide-rich gas stream and the hydrocarbon-rich gas;
• and
• a conduit for delivering the mixture of the carbon monoxide-rich gas stream and the hydrocarbon-rich gas stream to the direct reduction furnace and exposing the partially or completely reduced iron oxide to the mixture of the carbon monoxide-rich gas stream and the hydrocarbon-rich gas stream to increase the carbon content of resulting direct reduced iron, wherein the conduit for delivering the mixture of the carbon monoxide-rich gas stream and the hydrocarbon-rich gas stream to the direct reduction furnace is coupled to the direct reduction furnace corresponding to one or more of a transition zone and a cooling zone of the direct reduction furnace below a primary reduction zone of the direct reduction furnace, wherein the conduit for delivering the mixture of the carbon monoxide-rich gas stream and the hydrocarbon-rich gas stream to the direct reduction furnace is coupled to the direct reduction furnace at a point where the partially or completely reduced iron oxide in the one or more of the transition zone and the cooling zone of the direct reduction furnace contains 0.5-2.5% combined carbon before exposure to the mixture of the carbon monoxide-rich gas stream and the hydrocarbon-rich gas stream and up to 4.0% after.