Melt purification strategies for high-performance recycled steel

Electric arc furnace (EAF) steelmaking is pivotal for low-carbon steel, yet scrap-borne residual (tramp) elements increasingly constrain the upcycling of scrap into high-performance sustainable steel production. Conventional scrap pretreatment is often limited by the physical/chemical state of impurities, whereas melt purification can remove or immobilize residuals regardless of their occurrence form. Here we provide a critical, mechanism-oriented review of melt purification for key tramp elements in scrap-based EAF steelmaking (N, Cu, Sn, Zn, As, Sb, Pb, Bi). We unify disparate studies through a comprehensive research framework that couples thermodynamics (activity, volatility, stability of compounds), interfacial chemistry (surface-active poisoning, slag/metal oxygen potential gradients), and rate control (gas/liquid-phase mass transfer and reaction-site availability. We benchmark major routes gas metal reactions, engineered slags/fluxes, evaporation-assisted refining (vacuum/plasma/chemical volatilization), and electrochemical approaches against scale-up metrics including achievable removal depth, kinetics, additive consumption, refractory compatibility, secondary emissions/dust handling, and technology readiness. In addition, two case studies for the industrial-scale removal of nitrogen and copper illustrate how EAF-operational constraints dictate feasible process integration. Finally, we map research priorities for scalable deep purification, emphasizing multi-element co-control, byproduct valorization, and techno-economic optimization toward sustainable and high quality recycling of steel.