Two-thirds of the world's crude steel output of 1.95 billion mt in 2021 came from traditional blast furnace-based steel production, despite the inevitable shift to "green" steel to make it commercially viable and lessen the steel industry's carbon footprint. Conventional blast furnaces, on the other hand, are intricate multi-phase and multi-physics processes that only very slightly permit experimental access. The extended discrete element method (XDEM) is the primary representative of advanced multi-physics simulation technology (AMST), which is the recommended tool for gaining a deeper understanding of the complexity of these processes. The particulate phase - whether it be iron or coke particle - is handled as a discrete entity in this simulation framework, complete with motion and thermodynamic state. The latter in particular includes a multitude of chemical reactions that can be linked to particles, including phase changes like melting or combustion, drying, and reduction by the reducing agents hydrogen and carbon monoxide. The aforementioned processes involve a significant exchange of mass, momentum, and energy between the discrete and continuum phases. The latter is based on conventional computational fluid dynamics (CFD) and describes the flow of gases or liquids in the void space between the particles. The temperature and species distribution within a particle are determined by heat and mass transfer between the particle surfaces and the embedding gas phase, while an exchange of momentum, such as drag forces, creates a corresponding pressure drop over the reactor's height.
Results from using the XDEM technique to resolve the particulate and continuum phases are extremely detailed. The underlying physics of steel production, in particular the formation and shape of the cohesive zone as depicted in fig. 1, are revealed through an analysis of the results, which is crucial for design, operation, and addressing environmental challenges. Decision-makers are assisted by these findings in making well-informed choices.