Carburization in Direct Reduction: Effects of Various CO-H2 Gas Mixtures

Kurzfassung

Carbon monoxide and hydrogen exhibit distinct reduction behaviors in ironmaking, impacting both the practical process operation and the resulting product. While hydrogen offers enhanced rates of reduction, its reactions with iron oxides are globally endothermic. In contrast, the reduction with carbon monoxide is not only exothermic, but is also accompanied by carburization, bringing the necessary carbon in steel. This raises questions about the optimal gas mixtures and the source of the carbon-containing gas, which should preferably from renewable sources, such as biogenic wastes or residues. The availability of well-defined and comprehensive experimental data in the literature is currently limited. Direct reduction-grade iron-ore pellets have been reduced isothermally at temperatures from 973 to 1273 K in varying hydrogen/carbon monoxide gas mixtures. Weight changes were monitored using thermogravimetric analysis completed by analytical techniques allowing the further validation of the complex carbon deposition mechanism and the optimization of the direct reduction process.