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Metallurgical and Materials Transactions B

, Volume 42, Issue 1, pp 254–260 | Cite as

Solar Aluminum Production by Vacuum Carbothermal Reduction of Alumina—Thermodynamic and Experimental Analyses

  • M. Kruesi
  • M. E. Galvez
  • M. Halmann
  • A. SteinfeldEmail author
Article

Abstract

Thermochemical equilibrium calculations indicate the possibility of significantly lowering the onset temperature of aluminum vapor formation via carbothermal reduction of Al2O3 by decreasing the total pressure, enabling its vacuum distillation while bypassing the formation of undesired by-products Al2O, Al4C3, and Al-oxycarbides. Furthermore, the use of concentrated solar energy as the source of high-temperature process heat offers considerable energy savings and reduced concomitant CO2 emissions. When the reducing agent is derived from a biomass source, the solar-driven carbothermal reduction is CO2 neutral. Exploratory experimental runs using a solar reactor were carried out at temperatures in the range 1300 K to 2000 K (1027 °C to 1727 °C) and with total pressures in the range 3.5 to 12 millibar, with reactants Al2O3 and biocharcoal directly exposed to simulated high-flux solar irradiation, yielding up to 19 pct Al by the condensation of product gases, accompanied by the formation of Al4C3 and Al4O4C within the crucible. Based on the measured CO generation, integrated over the duration of the experimental run, the reaction extent reached 55 pct at 2000 K (1727 °C).

Keywords

Carbothermal Reduction Exergy Efficiency Reaction Extent Solar Reactor Sample Surface Temperature 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Nomenclature

α

absorptivity

ε

emissivity

σ

Stefan–Boltzmann constant (5.6705 × 10−8 W/m2K4)

cp

heat capacity (J/kg K)

d

thickness (mm)

k

thermal conductivity (W/m K)

m

mass (kg)

\( \dot{q}_{\text{solar}} \)

solar radiative flux (W/m2)

t

time (s)

T

temperature (K)

TC

thermocouple

WGS

water–gas shift

ΔH

enthalpy change (kJ/mol)

ΔG

Gibbs free energy change (kJ/mol)

Notes

Acknowledgments

The authors thank V. Gianini, P. Haueter, L. Schlumpf, and A. Frei for technical support with the reactor design and during the solar experimental campaign.

References

  1. 1.
    International Aluminum Institute: Aluminum for Future Generations Sustainability Update, http://www.world-aluminium.org, 2007.
  2. 2.
    W.T. Choate and J.A.S. Green: U.S. Energy Requirements for Aluminum Production, Historical Perspective, Theoretical Limits and New Opportunities, http://www1.eere.energy.gov/industry/aluminum/pdfs/al_theoretical.pdf, 2003.
  3. 3.
    W. Choate and J. Green: Light Metals 2006 Volume 2: Aluminum Reduction Technology , Ed. J. Galloway, Wiley, New York, NY, 2006, pp. 445-50.Google Scholar
  4. 4.
    J.H. Cox and L.M. Pidgeon: Can. J. Chem., 1963, vol. 41, pp. 671-83.CrossRefGoogle Scholar
  5. 5.
    M. Halmann, A. Frei, and A. Steinfeld: Energy, 2007, vol. 32, pp. 2420-27.CrossRefGoogle Scholar
  6. 6.
    T.J. Fruehan, Y. Li, and G. Cargin: Metall. Mater. Trans. B, 2004, vol. 35B, pp. 617–23.Google Scholar
  7. 7.
    R. Winand, M. Van Gysel, A. Fontana, L. Segers, and J.C. Carlier: Min. Process. Extractive Metall., 1990, vol. 99, pp. C105–C112.Google Scholar
  8. 8.
    J.M. Toguri and L.M. Pidgeon: Can. J. Chem., 1962, vol. 39, pp. 540-47.CrossRefGoogle Scholar
  9. 9.
    J.M. Toguri and L.M. Pidgeon: Can. J. Chem., 1962, vol. 40, pp. 1769-76.CrossRefGoogle Scholar
  10. 10.
    S. Ramakrishnan and P. Koltun: Resour. Conservat. Recycl., 2004, vol. 42, pp. 49-64.CrossRefGoogle Scholar
  11. 11.
    P. Loutzenhiser, O. Tuerk, and A. Steinfeld: J. Metals, 2010, vol. 62, pp. 49-54.Google Scholar
  12. 12.
    A. Steinfeld: Energy, 1997, vol. 22, pp. 311-16.CrossRefGoogle Scholar
  13. 13.
    J.P. Murray: Sol. Energy, 1999, vol. 66, pp. 133-42.CrossRefGoogle Scholar
  14. 14.
    A. Steinfeld, P. Kuhn, and J. Karni: Energy, 1993, vol. 18, pp. 239-49.CrossRefGoogle Scholar
  15. 15.
    A. Steinfeld, M. Brack, A. Meier, A. Weidenkaff, and D. Wuillemin: Energy, 1998, vol. 23, pp. 803-14.CrossRefGoogle Scholar
  16. 16.
    T. Osinga, U. Frommherz, A. Steinfeld, and C. Wieckert: J. Sol. Energ. Eng., 2004, vol. 126, pp. 633-37.CrossRefGoogle Scholar
  17. 17.
    J.P. Murray: A. Steinfeld, and E.A. Fletcher: Energy, 1995, vol. 20, pp. 695-704.CrossRefGoogle Scholar
  18. 18.
    J.P. Murray: J. Sol. Energ. Eng., 2001, vol. 123, pp. 125-32.CrossRefGoogle Scholar
  19. 19.
    M.E. Gálvez, A. Frei, F. Meier, and A. Steinfeld: Ind. Eng. Chem. Res., 2009, vol. 48, pp. 528-33.CrossRefGoogle Scholar
  20. 20.
    FactSage: Thermochemical Software & Database Package, Centre for Research in Computational Thermochemistry, Ecole Polytechnique de Montreal, Canada, www.crct.polymtl.ca, 2002.
  21. 21.
    National Institute of Standards and Technology: Standard Reference Data Program, Chemistry Webbook, http://webbook.nist.gov/chemistry.
  22. 22.
    A. Roine: HSC Chemistry 5, Outokumpu Research, Oy, Finland, 1997.Google Scholar
  23. 23.
    J. Petrasch, P. Coray, A. Meier, M. Brack, P. Haeberling, D. Wuillemin, and A. Steinfeld: J. Sol. Energ. Eng., 2007, vol. 129, pp. 405-11.CrossRefGoogle Scholar
  24. 24.
    L.O. Schunk, W. Lipiński, and A. Steinfeld: AIChE J., 2009, vol. 55, pp. 1659-66.CrossRefGoogle Scholar
  25. 25.
    F.H. Chung: J. Appl. Cryst., 1975, vol. 8, pp. 17-19.CrossRefGoogle Scholar
  26. 26.
    R. Müller and A. Steinfeld: Chem. Eng. Sci., 2008, vol. 63, pp. 217-27.CrossRefGoogle Scholar

Copyright information

© THE MINERALS, METALS & MATERIALS SOCIETY and ASM INTERNATIONAL 2010

Authors and Affiliations

  • M. Kruesi
    • 1
  • M. E. Galvez
    • 2
  • M. Halmann
    • 3
  • A. Steinfeld
    • 1
    • 4
    Email author
  1. 1.Department of Mechanical and Process EngineeringETH ZurichZurichSwitzerland
  2. 2.Instituto de CarboquimicaMiguel Luesma CastanZaragozaSpain
  3. 3.Department of Environmental Sciences and Energy ResearchWeizmann Institute of ScienceRehovotIsrael
  4. 4.Solar Technology LaboratoryPaul Scherrer InstituteVilligenSwitzerland

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