Extraction of Alumina and Alumina-Based Cermets from Iron-Lean Red Muds Using Carbothermic Reduction of Silica and Iron Oxides
Khanna R. Zinoveev D. Konyukhov Y. Li K. Maslennikov N. Burmistrov I. Kargin J. Kravchenko M. Mukherjee P.S.
August 2025Multidisciplinary Digital Publishing Institute (MDPI)
Sustainability (Switzerland)
2025#17Issue 15
A novel strategy has been developed for extracting value-added resources from iron-lean, high-alumina- and -silica-containing red muds (RMs). With little or no recycling, such RMs are generally destined for waste dumps. Detailed results are presented on the carbothermic reduction of 100% RM (29.3 wt.% Fe2O3, 22.2 wt.% Al2O3, 20.0 wt.% SiO2, 1.2 wt.% CaO, 12.2 wt.% Na2O) and its 2:1 blends with Fe2O3 and red mill scale (MS). Synthetic graphite was used as the reductant. Carbothermic reduction of RM and blends was carried out in a Tamman resistance furnace at 1650 °C for 20 min in an Ar atmosphere. Reduction residues were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), elemental mapping and X-ray diffraction (XRD). Small amounts of Fe3Si alloys, alumina, SiC and other oxide-based residuals were detected in the carbothermic residue of 100% RM. A number of large metallic droplets of Fe–Si alloys were observed for RM/Fe2O3 blends; no aluminium was detected in these metallic droplets. A clear segregation of alumina was observed as a separate phase. For the RM/red MS blends, a number of metallic Fe–Si droplets were seen embedded in an alumina matrix in the form of a cermet. This study has shown the regeneration of alumina and the formation of alumina-based cermets, Fe–Si alloys and SiC during carbothermic reduction of RM and its blends. This innovative recycling strategy could be used for extracting value-added resources from iron-lean RMs, thereby enhancing process productivity, cost-effectiveness of alumina regeneration, waste utilization and sustainable developments in the field.
alumina regeneration , cermets , ferro-silicon alloys , industrial waste , recycling , red mud
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School of Materials Science and Engineering (Ret.), The University of New South Wales, Sydney, 2052, NSW, Australia
Department of Mineral Processing and Industrial Wastes Recycling, National University of Science and Technology “MISIS”, Moscow, 119049, Russian Federation
School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, 100083, China
Engineering Centre, Plekhanov Russian University of Economics, Moscow, 117997, Russian Federation
Technical Physics Department, L.N. Gumilyov Eurasian National University, Astana, 010008, Kazakhstan
Moscow Power Engineering Institute, National Research University, Moscow, 111250, Russian Federation
Independent Researcher, Orissa, Bhubaneshwar, 751013, India
School of Materials Science and Engineering (Ret.)
Department of Mineral Processing and Industrial Wastes Recycling
School of Metallurgical and Ecological Engineering
Engineering Centre
Technical Physics Department
Moscow Power Engineering Institute
Independent Researcher
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