Using Water Hydrogen Instead of Reducing Gas in the Production of Direct Reduced Iron (DRI)

Abstract

Oil rich countries are using natural gas as a source for reducing gas (H₂ ≈75%, and CO ≈ 14%) for the production of DRI from iron oxide ore. In this research we are proposing a new source that is pure hydrogen (>99%) obtained from the electrolysis of water. The size of the hydrogen molecule is much smaller than that of carbon monoxide molecule, thus hydrogen molecule could penetrate much deeper into the crystal structure of the iron oxide resulting in greater degree of metallization. Since huge quantity of hydrogen is needed to reduce the iron oxide (e.g. to produce one million ton/year DRI), so prolonged electrolysis of alkaline aqueous solution is required; this will be accompanied by large quantity of oxygen gas liberated at the anode electrode (430000 tons/year) which is useful for industry and health purposes, as well as the production of about 108 tons/year heavy water residue, the last could have wide uses in the nuclear and other industries and also in research. In the standard processes using reducing gas the final step (3 hours) is cooling and carburizing step, during which carbon is deposited from carbon monoxide simultaneously with cooling. In case of pure hydrogen the step is different thus we call it “cooling and extra reduction step” in which hydrogen raises the degree of metallization instead of carbon deposition which inhibits extra reduction due to the sealing of the porosity of product sponge iron.