The steel industry faces significant challenges in its quest for decarbonization, driven by the urgent need to meet EU climate targets reducing CO2 emissions by 80-95%. Currently, steel production contributes approximately 7% of global CO2 emissions, with the predominant BF-BOF route accounting for 72% of production. [1, 2] Low-carbon alternatives such as the Scrap-EAF and DR-EAF routes require different resources and energy inputs, presenting a significant challenge when integrating them into already highly optimized steel plants. Sinter and coking plants - designed for continuous production, with limited ability to scale down - which supply essential resources and energy, must reduce their output if blast furnaces (BF) are replaced. This shift disrupts the energy balance and operational efficiency of these plants. Process simulation is invaluable for balancing complex, integrated processes and assessing lower-carbon technologies in steel production. Different model fidelities (black box, grey box, rigorous models) enable quick calculations of integrated flowsheets and detailed investigations of process steps, such as the sinter strand, under varying conditions. This highlights the importance of tailored simulations and achieve sustainable iron and steel manufacturing. [1] S. Budinis, P. Levi, H. Mandová and T. Vass, "Iron and Steel Technology Roadmap," International Energy Agency, 2020. [2] W. S. Association, Sustainability Indicators 2023 Report, World Steel Association, 2023.