Combined Decarbonizing Technologies for Treatment of Bauxite Residues

Srecko Stopic (), Richard Schneider, Duško Kostić, Isnaldi R. Souza Filho, Mitar Perušić, Elif Emil-Kaya and Bernd Friedrich
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Srecko Stopic: IME Process Metallurgy and Metal Recycling, RWTH Aachen University, 52056 Aachen, Germany
Richard Schneider: IME Process Metallurgy and Metal Recycling, RWTH Aachen University, 52056 Aachen, Germany
Duško Kostić: IME Process Metallurgy and Metal Recycling, RWTH Aachen University, 52056 Aachen, Germany
Isnaldi R. Souza Filho: Max-Planck-Institut for Sustainable Materials, Max-Planck-Strasse 1, 40237 Duesseldorf, Germany
Mitar Perušić: Faculty of Technology Zvornik, University of East Sarajevo, 75400 Zvornik, Republic of Srpska, Bosnia and Herzegovina
Elif Emil-Kaya: Department of Materials Science and Engineering, Norwegian University of Science and Technology, Høgskoleringen 1, 7034 Trondheim, Norway
Bernd Friedrich: IME Process Metallurgy and Metal Recycling, RWTH Aachen University, 52056 Aachen, Germany

Waste, 2025, vol. 3, issue 2, 1-26

Abstract: This study explores both pyrometallurgical and hydrometallurgical methods for decarbonizing and recovering valuable metals from bauxite residue, with hydrogen plasma reduction and direct acid leaching as the primary approaches. The goal is to offer innovative techniques for extracting metals from bauxite residue, a by-product of the Bayer process, which cannot be disposed of in an environmentally sustainable manner. Additionally, reducing the volume of bauxite residue through combined treatments is a key objective. In contrast to traditional carbon-based reductive melting, which generated significant CO 2 emissions, hydrogen is now being investigated as a cleaner alternative. Through hydrogen plasma reduction, approximately 99.9% of iron is recovered as crude metallic iron, which can be easily separated from the slag containing other valuable metals. Thermochemical analysis was used to predict slag formation and chemical analysis of slag during hydrogen reduction. To further recover metals like aluminum and titanium, the slag is subjected to sulfuric acid leaching under high-pressure of oxygen in an autoclave avoiding silica gel formation. The results demonstrated a leaching efficiency of 93.21% for aluminum and 84.56% for titanium, using 5 mol/L sulfuric acid at 150 °C, with almost complete iron recovery. Assisted ultrasound leaching of slag with sulphuric acid under atmospheric pressure leads to 54% leaching efficiency of titanium.

Keywords: hydrometallurgy; pyrometallurgy; hydrogen; bauxite residue; plasma (search for similar items in EconPapers)
JEL-codes: Q1 Q16 Q18 Q2 Q20 Q23 Q24 Q25 Q28 Q3 Q31 Q38 Q5 (search for similar items in EconPapers)
Date: 2025
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