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Alumina Production from Calcium Aluminate Slags with a Novel HCl-Based Metallurgical Process
Maria Bagani1, Amalia Bempelou1, Michail Vafeias1
1School of Mining and Metallurgical Engineering, National Technical University of Athens, 15780 Athens, Greece.
Journal of Sustainable Metallurgy
|September 2, 2025
Summary
This study presents a novel HCl-based process to produce high-purity alpha-aluminum oxide (α-Al2O3) from calcium aluminate slags. The method efficiently extracts aluminum and purifies it for calcination into α-Al2O3.
Area of Science:
- Metallurgical Engineering
- Inorganic Chemistry
- Materials Science
Background:
- Calcium aluminate slags are industrial byproducts with potential for valuable material recovery.
- Efficiently extracting aluminum from these slags is crucial for resource valorization.
Purpose of the Study:
- To develop and optimize an HCl-based process for producing high-purity alpha-aluminum oxide (α-Al2O3) from calcium aluminate slags.
- To investigate the key stages of aluminum extraction, purification, and conversion to α-Al2O3.
Main Methods:
- Leaching calcium aluminate slag with aqueous HCl to dissolve aluminum and precipitate silica.
- Purifying dissolved aluminum chloride hexahydrate (ACH) via HCl gas purging and acetone washing.
- Calcining purified ACH to produce α-Al2O3.
Main Results:
- Optimized leaching achieved approximately 90% aluminum extraction.
- ACH purity reached 97.5% after purification.
- Final α-Al2O3 product achieved 98.5% purity.
Conclusions:
- The developed HCl-based process is effective for producing high-purity α-Al2O3 from calcium aluminate slags.
- The multi-stage approach, including leaching, purification, and calcination, yields a valuable end product.
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