2026 Botinha Chromium Low Carbon Steelmaking Review

The steel industry is transitioning toward decarbonization and increased circularity, driving a growing dependence on scrap. However, limited availability of high-quality scrap forces producers to use more mixed or lower grade scrap streams, increasing variability in tramp element content—especially chromium. As a result, maintaining controlled chromium levels in liquid steel has become challenging. Chromium behavior during steelmaking is governed by a complex interplay of thermodynamics and mass transfer processes. Yet much of the mechanistic understanding of chromium distribution derives from high alloy and stainless steelmaking systems, where slag chemistries and oxygen potentials differ markedly from low carbon steel production, making direct transfer of knowledge challenging and often nontrivial. In parallel with controlling chromium in steel, the oxidation of chromium into the slag introduces additional sustainability concerns, since Cr-bearing slags may limit future slag applications unless chromium is effectively immobilized, increasing resistance to form environmentally harmful Cr6+ species. This critical literature review synthesizes current knowledge on chromium distribution in the blast-furnace–basic-oxygen-furnace (BF–BOF) route, examining the thermodynamics of chromium oxidation, the influence of Cr2+/Cr3+ on slag-network formation and oxide activities, the stability of Cr-containing phases, and the kinetics of chromium transfer at the metal–slag interface and within the slag phase. By integrating these thermodynamic, structural, and kinetic perspectives, the review identifies the mechanisms controlling chromium behavior and highlights key research needs, defining a chromium retention capacity concept for slags to support improved impurity management and more sustainable process operation.