Systems and methods for direct reduction of iron ore

A method for producing direct reduced iron (DRI) using a shaft furnace comprising a heating zone, a reduction zone, and a cooling zone, the method comprising:

• loading iron ore into a furnace at the heating zone, wherein the iron ore is heated to a target temperature;
• flowing a bustle gas comprising hydrogen into the shaft furnace at a downstream end of the reduction zone, wherein the bustle gas is preheated without combustion of the hydrogen to a temperature of about 650° C. to about 1100° C. before being flowed into the shaft furnace, and flows within the shaft furnace through the reduction zone and into the heating zone;
• optionally flowing a heat carrier gas into the shaft furnace at the downstream end of the reduction zone, wherein the heat carrier gas comprises an inert gas and is preheated to a temperature of about 650° C. to about 1100° C. before being flowed into the shaft furnace;
• flowing the iron ore from the heating zone into the reduction zone, wherein the iron ore is reduced to iron through reaction of the iron ore with the preheated bustle gas, thereby producing direct reduced iron (DRI);
• flowing a cooling hydrogen gas into the cooling zone;
• and
• flowing the direct reduced iron (DRI) from the reduction zone into the cooling zone to cool the direct reduced iron by heat exchange with the cooling hydrogen gas, wherein the cooling hydrogen gas, after heat exchange with the direct reduced iron (DRI) flows into the reduction zone,
• wherein:
• a molar ratio of H2:Fe2O3 of about 6 mol/mol is a minimum hydrogen demand for a target 95% metallization of iron from the iron ore,
• when the heat carrier gas is not present, the preheated bustle gas is flowed into the shaft furnace such that an amount of hydrogen within the reduction zone is greater than the minimum hydrogen demand,
• when the heat carrier gas is present, the bustle gas is flowed into the shaft furnace such that an amount of hydrogen within the reduction zone is equal to or greater than the minimum hydrogen demand,
• and
• wherein hydrogen present in the shaft furnace flows from the cooling and/or reduction zones upstream into the heating zone to heat the iron ore through heat exchange before exiting as a top gas, and optionally, when present, the heat carrier gas flows from the reduction zone upstream into the heating zone to heat the iron ore through heat exchange before exiting with the top gas.

A system for producing direct reduced iron, comprising:

• a shaft furnace a heating zone, a reduction zone, and a cooling zone;
• an iron ore source in fluid communication with the heating zone to load iron ore into the heating zone;
• a bustle gas source for flowing bustle gas comprising hydrogen into the shaft furnace through a bustle gas inlet disposed at a downstream end of the reduction zone;
• optionally a heat carrier gas source for flowing a heat carrier gas comprising an inert gas into the shaft furnace through a heat carrier gas inlet loaded at a downstream end of the reduction zone or through the bustle gas inlet;
• a bustle gas preheating unit arranged between the bustle gas source and the bustle gas inlet, wherein the bustle gas preheating unit is adapted to preheat the bustle gas without combustion of the hydrogen to a temperature of about 650° C. to about 1100° C.;
• optionally a heat carrier gas inlet arranged between the heat carrier gas source and the heat carrier gas inlet or bustle gas inlet through which the heat carrier gas is flowed into the shaft furnace, wherein the heat carrier gas preheating unit preheats the heat carrier gas to a temperature of about 650° C. to about 1100° C.;
• a cooling hydrogen gas source for flowing cooling hydrogen gas into the shaft furnace through cooling hydrogen gas inlet disposed in the cooling zone, wherein:
• the iron ore is adapted to be flowed downstream from the heating zone to the reduction zone, wherein upon interaction with hydrogen in the reduction zone the iron ore is reduced to iron by reaction with the hydrogen and to thereby produce direct reduced iron,
• the direct reduced iron produced in the reduction zone is adapted to be flowed downstream to the cooling zone wherein it is cooled by heat exchange with the cooling hydrogen gas, and
• a molar ratio of H2:Fe2O3 of about 6 mol/mol is a minimum hydrogen demand for a target 95% metallization of iron from the iron ore,
• when the heat carrier gas is not present, the preheated bustle gas is adapted to be flowed into the shaft furnace such that an amount of hydrogen in the reduction zone is greater than the minimum hydrogen demand,
• when the heat carrier gas is present, the bustle gas is flowed into the shaft furnace such that an amount of hydrogen in the reduction zone is equal to or greater than the minimum hydrogen demand, and
• hydrogen present in the shaft furnace from the bustle gas and/or cooling hydrogen gas is adapted to flow from the cooling and/or reduction zones upstream into the heating zone to heat the iron ore through heat exchange before exiting as a top gas, and optionally when present, the heat carrier gas is adapted to flow from the reduction zone upstream into the heating zone to heat the iron ore through heat exchange before exiting with the top gas.