Work

Sustainable pathway towards red mud valorization through biomass thermochemical conversion and metals recovery

Year: 2025

Type: article

Abstract: Red mud is a hazardous waste from the alumina refining process. Processing 1 tonne of alumina yields 1-1.5 tonnes of red mud. A first-of-its-kind understanding of biomass-based pathway for recovering iron in red mud is presented. Simultaneous red mud reduction and biomass gasification (SRG) is proposed to produce zero-valent iron, which could be isolated by weak magnetic separation and re-integrated into the iron-making industry, while the other valuable metals (rare earth elements, Sc, V) are potentially concentrated in the paramagnetic fraction. The stages of the synergetic red mud-biomass phenomena were investigated through thermogravimetric analyses followed by XRD characterizations. SRG achieved a complete reduction from Fe3+ to Fe0 at temperatures close to 900 °C under an inert atmosphere. Bench-scale SRG experiments were also performed to study compositions of gaseous and tar products. Increased production of syngas (CO and H2) was verified, and red mud was found to have tar-cracking catalytical activity.

Source: Bioresource Technology

DOI: 10.1016/j.biortech.2025.132847

Authors: Pedro Henrique Cabral de Souza, Klas Engvall, Frederico Marques Penha, Efthymios Kantarelis, Shareq Mohd Nazir

Institution: KTH Royal Institute of Technology

Language: English

Topic: Bauxite Residue and Utilization

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Responsible consumption and production, Affordable and clean energy

Open Access status: hybrid

Estimated APC paid: $4,880