Lanthanides extraction processes in molten fluoride media. Application to nuclear spent fuel reprocessing

Pierre Taxil (1) , Laurent Massot (1) , Christophe Nourry (1) , Mathieu Gibilaro (1) , Pierre Chamelot (1) , Laurent Cassayre (1)

1 LGC - Laboratoire de Génie Chimique

This paper describes four techniques of extraction of lanthanides elements (Ln) from molten salts in the general frame of reprocessing nuclear wastes; One of them is chemical: the precipitation of Ln ions in insoluble compounds (oxides or oxifluorides); the others use electrochemical methodology in molten fluorides for extraction and measurement of the progress of the processes: first electrodeposition of pure Ln metals on an inert cathode material was proved to be incomplete and cause problems for recovering the metal; electrodeposition of Ln in the form of alloys seems to be far more promising because on one hand the low activity of Ln shifts the electrodeposition potential in a more anodic range avoiding any overlapping with the solvent reduction and furthermore exhibit rapid process kinetics; two ways were examined: (i) obtention of alloys by reaction of the electroreducing Ln and the cathode in Ni or preferably in Cu, because in this case we obtain easily liquid compounds, that enhances sensibly the process kinetics; (ii) codeposition of Ln ions with aluminium ions on an inert cathode giving a well defined composition of the alloy. Each way was proved to give extraction efficiency close to unity in a moderate time.

Mots clés: Nuclear wastes; Fission products; Lanthanides; Molten fluorides; Electrodeposition; Oxide precipitation; Alloys electrodeposition

Domaines: Génie des procédés; Génie chimique

Pierre Taxil, Laurent Massot, Christophe Nourry, Mathieu Gibilaro, Pierre Chamelot, et al.. Lanthanides extraction processes in molten fluoride media. Application to nuclear spent fuel reprocessing. Journal of Fluorine Chemistry, 2009, 130 (1), pp.94-101. ⟨10.1016/j.jfluchem.2008.07.004⟩. ⟨hal-03572948⟩