Systematics of the thermodynamic properties of trivalent f-elements in a pyrometallurgical bi-phase extraction system

摘要

In order to strengthen the comprehensive understanding on the mechanism of the extraction of f-elements in a pyrometallurgical bi-phase extraction system, which is usable for dry-reprocessing of spent nuclear fuels, some thermodynamic quantities related to their affinity to the solvent materials were studied. A reductive extraction system consisting of molten alkaline chloride and liquid Pi and Zn was selected for this purpose, and the excess free energy of tri-chlorides of lanthanides associated with their solution into alkaline chloride molten salt was estimated. The standard Gibbs energy change of formation of diluted liquid alloy of lanthanides with Pi and Zn was discussed with the aid of a semi-empirical model for alloy formation. Their systematic variations along the f-series were studied to elucidate the distribution behaviors. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 12]