(173ad) Hydrogen-Based Processing of Mineral Iron Carbonate; Iron Production Combined with Catalytic CO/CO2 Hydrogenation

Direct reduction of mineral iron carbonate (siderite ore) with hydrogen provides an alternative route for future sustainable, pig iron production. It offers high potential for carbon dioxide emission mitigation, especially when combined with valorization of the process gas. When processing siderite ore in hydrogen atmosphere at ambient pressure within a temperature window of 600 to 800 °C, it is possible to alter the carbon monoxide/carbon dioxide ratio of the exiting process gas. Suitable valorization strategies to upgrade the CO/CO₂-rich process gas containing excess hydrogen from the direct reduction process are catalytic CO/CO₂ hydrogenation to methane and methanol. The efficiency of the hydrogenation process highly depends on the choice of the catalyst. Ni-based catalysts have proven successful for methane synthesis, whereas Cu-based catalysts are applied for methanol synthesis. To close the raw material cycle and provide a complete technology concept for iron production based on the direct reduction of siderite ore, MgO stands out as a carrier material for the catalytically active components Ni and Cu. As MgO acts as a suitable slag former, the spent Ni/MgO and Cu/MgO catalysts from methane and methanol synthesis can be recycled in the blast-oxygen furnaces in the steel and copper industry after their lifetime. Based on the experimental findings a complete technology concept is provided that considers the origin and quality of the reducing agent hydrogen in addition to the further use of the process gas.