Proprietà fisico-chimiche e reattività delle fusioni silicatiche mediante modellazione termodinamica: applicazione per la valorizzazione e l’ingegnerizzazione delle scorie siderurgiche

This work investigates the thermodynamic behavior, phase stability, and energy content of steelmaking slags, integrating advanced equilibrium modeling with experimental characterization techniques. Steelmaking slags, generated across Basic Oxygen Furnace (BOF), Electric Arc Furnace (EAF), and Ladle Furnace (LF) operations, represent one of the largest by-product streams in the metallurgical industry, yet their potential as secondary raw materials remains underutilized. The research employs FactSage thermodynamic simulations to predict slag-metal interactions, identify stable and metastable phases, and support selective reduction strategies for recovering valuable elements and producing functional materials. Multiple valorization pathways are explored: the transformation of white steel slag into synthetic hydraulic binder precursors, the deferrization of EAF black slag through aluminothermic and silicothermic processes, and the recovery of strategic ferroalloys from ladle slag through an integrated thermodynamic and experimental approach. Experimental validation through XRD, XRF, and SEM-EDS confirms the simulated phase assemblages, while providing crucial insights into the microstructural evolution and chemical reactivity of processed slags. The STILLMETAL project, which forms part of this research, demonstrates the feasibility of producing ferrosilicon alloys from white ladle slag through aluminothermic reduction, generating both metallic products and residual oxide phases suitable for industrial reuse. The research extends beyond traditional thermodynamic analysis to include exergy evaluation and life cycle assessment. These complementary approaches quantify the untapped thermal energy contained in molten slags and assess the environmental benefits of the proposed valorization routes, highlighting significant reductions in carbon footprint compared to conventional production processes. The results demonstrate that thermodynamic modeling, when integrated with empirical validation, can serve as a powerful decision-making tool to optimize slag reuse, enhance process efficiency, and minimize environmental risks. This work contributes to redefining steelmaking slags from waste residues to strategic resources, supporting the transition toward more sustainable and circular metallurgical practices.