Journal article
Vacuum Carbothermic Reduction of Alumina
- Halmann, Martin Department of Environmental Sciences and Energy Research, Weizmann Institute of Science, Rehovot, Israel
- Steinfeld, Aldo Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland; Solar Technology Laboratory, Paul Scherrer Institute, Villigen, Switzerland
- Epstein, Michael Solar Technology Laboratory, Paul Scherrer Institute, Villigen, Switzerland
- Vishnevetsky, Irina Solar Research Facilities Unit, Weizmann Institute of Science, Rehovot, Israel
Published in:
- Encyclopedia of Aluminum and Its Alloys. - CRC Press. - 2019
English
The current industrial production of aluminum from alumina is based on the electrochemical Hall-Héroult process, which has the drawbacks of high-greenhouse gas emissions, reaching up to 0.70 kg CO2-equiv /kg Al, and large energy consumption, about 0.055 GJ/kg Al. An alternative process is the carbothermic reduction of alumina. Thermodynamic equilibrium calculations and experiments by induction furnace heating indicated that this reaction could be achieved under atmospheric pressure only above 2200° C. Lower required reaction temperatures can be achieved by alumina reduction under vacuum. This was experimentally demonstrated under simulated concentrated solar illumination and by induction furnace heating. By decreasing the CO partial pressure from 3.5 mbar to 0.2 mbar, the temperature required for almost complete reactant consumption could be decreased from 1800°C to 1550°C. Deposits condensed on the relatively cold reactor walls contained up to 71 wt% of Al. Almost pure aluminum was observed as Al drops, while a gray powder contained 60–80% Al and a yellow-orange powder contained only Al4 C3 , Al-oxycarbides and Al2 O3 .
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- English
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- https://sonar.ch/global/documents/173707
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