Styrian mining and Austrian iron and steel production look back on a long tradition. This is based, among other things, on siderite ore, a carbonatic iron ore, from the Erzberg deposit in Styria. Due to its carbonatic nature, smelting siderite ore is more costly and contributes to additional CO2 emissions compared with iron oxide-based ores; and this in one of the already highest-emission sectors of industry. Siderite ore smelting requires calcination by heating in air to hematite; with the purpose of releasing CO2 from the ore and minimizing the CO2 content in the reduction stage and thus grain breakdown in the blast furnace.
The direct reduction of siderite ore with hydrogen presented in the SteirerEiSen project makes it possible to form iron from the iron carbonate in one process step and thus bypasses the conventional two-stage route. Direct CO2 emissions are reduced by more than 60%. Carbon monoxide and methane are formed in the process gas for further use. Comparing the direct hydrogen reduction of siderite with the hydrogen reduction of hematite, the reducing agent requirement is 33% lower for the reduction of siderite. It is also advantageous that direct reduction can be carried out at significantly lower process temperatures compared to the calcining and reducing process steps in the blast furnace.
The cooperation of Graz University of Technology (Institute of Chemical Engineering and Environmental Technology), MU Leoben (Chair of Mineral Processing) and VA Erzberg GmbH enables a holistic view of this promising technology concept - from the ore grain to the finished feedstock for the smelter.