An alternative approach for pig iron production from mineral siderite.

The iron and steel industry is one of most relevant industrial sectors worldwide. The blast furnace process makes mainly use of hematite (Fe₂O₃) as primary iron source, covering about two-thirds of the global steel production. The reducing agent and primary energy source for the blast furnace process is coke. Austria and China have major mineral iron carbonate (= siderite, FeCO₃) reserves, which are used as ores for iron and steel production. Siderite beneficiation is challenging, because of the low iron content of the ore compared to magnetite and hematite ores. The industrial practice is to blend siderite with other high-grade ores in the sinter plant. During the sintering process, siderite is converted to hematite through roasting in air. The sinter product is fed to the blast furnace where it is preferably reduced with coke via CO, producing at least 1.5 mole CO₂ per mole of iron due to the stoichiometry of reaction. Consequently, at least 2.5 mole CO₂ are emitted during the production of 1 mole of iron from iron carbonate.

Aim of this project is to develop an alternative process for pig iron production by direct reduction of siderite with hydrogen. The reduction process is followed by separation of the unconverted ore matrix (gangue) for direct use of the pig iron in the steel converter. In the ideal case of complete carbonate conversion, elemental iron is formed together with CO₂, carbon monoxide (CO), methane (CH₄) or higher hydrocarbons (C_xH_y), resulting in significant CO₂ emission reduction. Technology development is based on mineral ore from the Styrian Erzberg. The process shows high potential for significant reduction of CO₂ emissions and less specific energy demand.

• Montanuniversität Leoben, Institut für Aufbereitung und Veredlung

• VA Erzberg GmbH