Computational and analytical chemistry: Methodology to study chemical reactions between sodium, calcium, and aluminum fluorides in molten cryolite
✍ Scribed by Frédéric Bouyer; Gérard Picard; Jean-Jacques Legendre
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 253 KB
- Volume
- 61
- Category
- Article
- ISSN
- 0020-7608
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✦ Synopsis
Reaction constants and composition profiles in molten cryolite have been theoretically investigated. Hartree᎐Fock and density functional calculations were applied to determine Ž . the exact nature structure and energetic of complexes existing in molten cryolite. The aim of this work was thus the understanding of chemical processes occurring in the electrowinning of aluminum and was a demonstration of how computational chemistry Ž . based on density functional theory can help us to determine structures and reaction energies in particularly complex medium such as cryolite. An analytical study, based on mass balance and equilibrium constants has been undertaken. This was performed on molecular liquid entities taking into account the four-, five-and sixfold coordinated aluminum complexes of the AlF ᎐3NaF melt system. Moreover, the effect of calcium has 3 been studied by substituting two sodium atoms with one calcium atom, thus leading to Ž . the CaNaAlF system. Two conformers instead of three for Na were obtained for this 6 system. They can be described as representing the four-and fivefold coordinated aluminum complexes in molten cryolite. The structurizing effect of calcium was clearly *To whom correspondence should be addressed.