Green steel production: from potential analysis to implementation at the Salzgitter steel works

At around 28 %, the production of crude steel via the blast furnace route accounts for a large proportion of industrial CO₂ emissions in Germany. This is why steel producers are working intensively on converting steel production to the direct reduction process. As one of the pioneers in this field, Salzgitter AG has already been working for six years in a consortium with the Fraunhofer Institutes IKTS, ISI and UMSICHT on how low-CO₂ crude steel production can be realized using green hydrogen. In the two successive research projects “MACOR” and “BeWiSe”, funded by the German Federal Ministry of Education and Research (BMBF), it has already been demonstrated that this approach can reduce CO₂ emissions by at least 95 %. Supplemented by further measures, CO₂-free steel production is thus possible. The technical conditions for a changeover and questions of acceptance were also investigated. As part of its SALCOS^® project, Salzgitter AG plans to convert conventional steel production via blast furnaces to the direct reduction process using hydrogen by 2033. Construction work for the gradual conversion has already begun and one third of the steel production capacity will already have been transformed to the low-CO₂ process by 2026.

Supporting research project “BeWiSer” focuses on resource efficiency

To further optimize the planned SALCOS^® process route, the consortium launched the BMBF project “BeWiSer” in July 2023 which had its kickoff on September 26 in Salzgitter. This project examines the entire process chain in terms of resource and energy efficiency. The structural transformation of steel production already initiated on the part of Salzgitter AG will thus receive further scientific support. For example, the project will be investigating how biogenic materials can be used as a substitute for coal and natural gas in order to adjust the required carbon content in steel. The efficient use of water is also a priority in the project, as large quantities of water are needed in the production of green steel for electrolysis, among other things. For this reason, the water formed during iron ore reduction with hydrogen is to be processed as far as possible for reuse. The plant builder TS ELINO is a new member of the project consortium for the in-process recycling of the iron-bearing dusts produced during processing. This will lead to a further increase in resource efficiency of green steel production. A pilot plant has been set up at Salzgitter AG for the application-oriented investigation of direct reduction. Here, among other things, numerical models of the direct reduction process can be validated and further developed.

Applied research provides important contributions for the transformation of steel production

“As part of the joint research work, it was possible to build up unique competencies in the consortium and achieve important scientific results. These make a significant contribution to reducing industrial CO₂ emissions,” explains Dr. Matthias Jahn, head of the Energy and Process Engineering department at Fraunhofer IKTS in Dresden. Fraunhofer IKTS has managed the research efforts ever since the feasibility study was carried out as part of the “MACOR” project and contributes to the research results with the simulation of the process chain as well as the studies on the kinetics of direct reduction. Dr. Alexander Redenius, Head of Resource Efficiency and Technology Development at Salzgitter Mannesmann Forschung, adds: “The conversion of crude steel production to the direct reduction process during ongoing operation of the steel mill represents a major challenge. Through close cooperation with the research institutes, important foundations are being laid for optimized plant operation of the associated process steps in order to successfully implement the transformation process of steel production in Salzgitter.”