Vacuum Carbothermic Production of Aluminum and Al-Si Alloys From Kaolin Clay: A Thermodynamic Study |
| |
Authors: | Martin Halmann |
| |
Affiliation: | 1. Department of Environmental Sciences and Energy Research , Weizmann Institute of Science , Rehovot , Israel m.halmann@weizmann.ac.il |
| |
Abstract: | Examination of the thermodynamic constraints for the carbothermic reduction of iron-free kaolinite, Al2Si2O5(OH)4, or of its calcination product mullite, Al6Si2O13, either at atmospheric pressure or under vacuum of 10?3 to 10?5 bar, indicates the conditions required at equilibrium to produce either elementary Al or Al-Si alloys. At atmospheric pressure, a very high temperature of 3200 K would be required to obtain from Al2Si2O5(OH)4 + 9C an Al-Si alloy with 39 wt.% Si. At 10?4 bar and 1800 K, the predicted Al-Si alloy would contain 2.4 wt.% Si. From mullite, the reaction of Al6Si2O13 + 13C at 10?4 bar and either 1800 K or 2200 K should produce an Al-Si alloy with 0.65 or 24 wt.% Si. The CO produced by the carbothermic reactions may be by water-gas shift converted to syngas, and further either to methanol or by a Fischer–Tropsch reaction to liquid fuels or chemical intermediates. Concentrated solar energy may be used to supply the required process heat of these high-temperature reactions. |
| |
Keywords: | alumina aluminum carbothermic reduction clay kaolin kaolinite mullite thermodynamics vacuum reaction |
|
|