NEWIRON  

Production d’acier durable par réduction de minerais de fer à partir d’hydrogène renouvelable

Steel is the backbone material of modern civilization. While it enables sustainability via its high recyclability rates, its primary production has strong negative impacts on the environment. On average, each ton of produced crude steel is accompanied by a staggering amount of ~2.1 tons of CO2. This enormous number currently represents ~8% of all CO2 emissions on the planet and qualifies the ironmaking sector as the heaviest individual industrial CO2 emitter. This is because, currently, iron is extracted from its ores by means of redox chemical reactions that employ carbon-carrier substances as reducing agents, thus leading to CO2 as the major by-product. To fight global warming, a drastic reduction of 80% in all emissions by 2050 is needed and the most polluting sources must be tackled.

Therefore, it is imperative that novel and sustainable ironmaking routes must be explored and urgently implemented in the coming decades. Through the project NEWIRON, we aim to investigate the replacement of C by hydrogen-containing gases, produced via renewable sources, to serve as reducing agents for iron ores. In this case, water is the direct by-product rather than CO2. NEWIRON will particularly focus on three alternative routes, each of them with currently very different technology readiness levels (TRL): hydrogen-based direct reduction (DR), hydrogen plasma smelting reduction (HPSR), and hydrogen solar-driven reduction (SDR) via concentrated solar heating. Here, we aim to tackle the emerging challenges in these routes. In DR, the growing scarcity of high-grade iron ore concentrates poses difficulties in the production of high-quality pellets to feed shaft furnaces.

Therefore, low-grade iron ores will need to serve as an alternative source for iron. NEWIRON proposes to investigate the direct reduction of iron ores containing high content of impurities (SiO2, Al2O3) with the aim of shedding light on the competing side chemical transformations and their impact on the overall reduction kinetics. Second, it is possible that, for economic and technical reasons, a part of the future green hydrogen would be transported under the form of ammonia (NH3), a high-density hydrogen carrier. Using ammonia could also be advantageous in terms of activation temperature and protection from oxidation.

We will study the direct reduction of iron ore by ammonia (NH3). HPSR has only been investigated in reactors possessing one single DC electrode. Here, we propose the realization of lab scale HPSR experiments using an AC 3-electrode reactor. The need for such investigation is clear PEPR SPLEEN – AMI 6 / 12 when one considers retrofitting existing and already operational electric arc furnaces for hydrogen plasma purposes. Since HPSR requires only diluted H2 (max. 10% H2), we aim to identify and test alternative and cheap dilution gases, such as the ones stemming from the autothermal pyrolysis of biomass (CO, CO2, H2, CH4, N2). The direct use of solar energy is probably the pathway among the three where the lowest CO2 emissions could be achieved, although it is found in its infancy. NEWIRON proposes to build a pilot reactor to maximize the reduction yield under concentrated solar irradiation using both H2 and NH3 as reducing agents. Since the main objective in studying these three different routes is to mitigate climate change and other environmental impacts, life cycle assessment (LCA) and optimization of each alternative process will be performed (including reagents production, supply and storage, infrastructure and equipment construction). NEWIRON aims at providing scientific-based findings to further develop the TRL of these three alternative and C-lean hydrogen-based reduction routes, thus helping to abate the CO2 emissions from the iron- and steelmaking sector.

Le consortium

Ecole Centrale de Nantes, Institut National des Sciences Appliquées de Toulouse, Université de Lorraine, Institut Jean Lamour, Laboratoire Réactions et Génie des Procédés, PROcédés, Matériaux et Energie Solaire

Coordination