Upcycling Anodic Sludge from Aluminum Anodizing: Leaching Efficiency and Thermal Conversion into Refractory Materials

Fausto Acosta, Cristhian Feijoo, Alfredo S. Sangurima-Cedillo, Alicia Guevara and Carlos F. Aragón-Tobar ()
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Fausto Acosta: Department of Extractive Metallurgy, Escuela Politécnica Nacional, Ladrón de Guevara E11-253, Quito 170525, Ecuador
Cristhian Feijoo: Instituto de Investigación Geológico y Energético (IIGE), Quito 170518, Ecuador
Alfredo S. Sangurima-Cedillo: Department of Extractive Metallurgy, Escuela Politécnica Nacional, Ladrón de Guevara E11-253, Quito 170525, Ecuador
Alicia Guevara: Department of Extractive Metallurgy, Escuela Politécnica Nacional, Ladrón de Guevara E11-253, Quito 170525, Ecuador
Carlos F. Aragón-Tobar: Department of Extractive Metallurgy, Escuela Politécnica Nacional, Ladrón de Guevara E11-253, Quito 170525, Ecuador

Sustainability, 2025, vol. 17, issue 18, 1-16

Abstract: Anodic sludges generated in the production of aluminum profiles pose both an environmental and economic problem due to their accumulation in municipal landfills. This study investigates their valorization as a raw material for industry through leaching and calcination processes. The solid residue was characterized both physically and chemically. In the leaching process, concentrations of NaOH (1–2.5 M) and solid percentages (10–30%) were evaluated, achieving a 93.7% recovery of aluminum as sodium aluminate with 2 M NaOH and 10% solids. In the calcination process, the sludges were treated at temperatures ranging from 200 to 1600 °C, and different particle sizes (−3 + 1 mm, −1000 + 400 μm, −400 + 200 μm). The best result from calcination was obtained at 1600 °C, producing a refractory material composed of corundum (α-Al 2 O 3 ) and diaoyudaoite (NaAl 11 O 17 ).

Keywords: aluminum; anodic sludge; refractory materials (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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