Valorization of iron and high value metals from dust generated during grinding of electroslag remelted ingots.

Electroslag remelting (ESR) is a secondary refining technique employed to produce ultra-clean specialty steel grades with minimal inclusions and controlled composition. ESR ingots require surface grinding to eliminate defects such as surface cracks, generating fine metallic dust rich in valuable alloying elements. Proper valorization of this dust is important both to mitigate occupational and environmental hazards and to recover commercially significant metals, thereby supporting circular economy objectives within specialty steelmaking. In the present study, dust collected from the surface grinding of SS321 grade ESR ingots was characterised using X-ray fluorescence, X-ray diffraction and wet chemical analysis, confirming a predominantly metallic composition with 74.83 wt% Fe, 10.87 wt% Cr, 7.05 wt% Ni, and 0.65 wt% Mo with no oxide phases detected. An induction furnace-based single-step recovery route was proposed and validated through a pilot-scale trial with a 65 kg charge comprising 30 kg of SS321 electrode material and 35 kg of grinding dust. Elemental mass balance calculations yielded recovery efficiencies of 88.4% for Fe, 85.0% for Cr, 93.1% for Ni, and 73.1% for Mo. The observed recovery hierarchy is consistent with thermodynamic predictions from Ellingham diagram analysis and is corroborated by a CALPHAD-based simulation in FactSage 8.4 that reproduced the experimental ingot composition to within 2% for all four elements of interest. Total electrical energy consumption was 74 kWh, corresponding to approximately 1.29 kWh per kilogram of recovered material, substantially lower than the approximately 22 kWh/kg required for virgin stainless steel production and the approximately 5 kWh/kg associated with conventional scrap remelting. Economic analysis yielded a net value generation of INR 407.6 (GBP 3.33) per kilogram of grinding dust processed. The output ingot composition closely resembles the input electrode grade, enabling direct reuse as an ESR electrode. A generalised thermodynamically grounded process selection framework is additionally proposed to extend this methodology to other steel grades and specialty alloys.