Hydrogen Plasma Refining Coupled with Solid-State Reduction for Sustainable Ironmaking: Hydrogen Plasma Refining Coupled with Solid-State Reduction for Sustainable Ironmaking

The growing demand for sustainable ironmaking and steel refining technologies has intensified the need for efficient utilization of industrial fines and low-grade resources. In the present study, waste iron ore fines and lime fines were utilized to produce highly fluxed iron ore pellets and their potential application in molten pig iron refining was systematically investigated. Pellets with varying basicity were prepared and hardened at elevated temperatures to evaluate their phase evolution, mechanical properties, reducibility, and refining performance.Mineralogical characterization revealed hematite as the dominant phase in the iron ore, while increasing pellet basicity promoted the formation of calcium ferrite and dicalcium ferrite phases. The development of calcium ferrite significantly enhanced pellet strength, with pellets fired at 1200°C exhibiting strengths exceeding 500 kg/pellet. Reduction studies carried out under both carbonaceous and hydrogen atmospheres demonstrated that pellet basicity strongly influenced reduction kinetics and metallization behavior. Hydrogen reduction resulted in superior reducibility, achieving up to 90% reduction, and produced characteristic iron whisker morphologies that facilitated rapid oxygen removal.The performance of partially and highly reduced fluxed pellets was further evaluated for impurity removal from molten pig iron during electric arc, induction, and plasma-assisted melting operations. Thermodynamic and kinetic analyses revealed that the removal efficiencies of silicon, manganese, phosphorus, sulfur, and carbon were strongly dependent on the reduction degree of the fluxed pellets. Highly reduced pellets exhibited enhanced desulfurization capability, while partially reduced pellets were found to be more effective for phosphorus removal. Plasma-assisted refining under hydrogen atmosphere demonstrated remarkable impurity removal efficiencies, particularly for carbon, silicon, and sulfur.The study establishes a sustainable pathway for the valorization of iron ore and lime fines through the production of highly fluxed direct reduction pellets. The findings demonstrate that appropriately engineered fluxed pellets can serve not only as iron-bearing feedstock but also as multifunctional refining agents for efficient impurity removal during secondary steelmaking operations, contributing to resource conservation and low-carbon ironmaking. Speaker: Dr Raj Kumar Dishwar

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