Conditions Extrêmes et Matériaux : Haute Température et Irradiation
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2008

ACL
doi

D.Hudry, I.Bardez, A.Rakhmatullin, C.Bessada, F.Bart, S.Jobic, P.Deniard, 'Synthesis of rare earth phosphates in molten LiCl-KCl eutectic: Application to preliminary treatment of chlorinated waste streams containing fission products', J. Nucl. Mater. 381 284-289 (2008) doi:10.1016/j.jnucmat.2008.09.005

The precipitation of rare earth phosphates (RE = La, Ce, Pr, Nd, Lu), from RECl3 was investigated in molten LiCl-KCl eutectic at 500°C in air. Ammonium dihydrogenphosphate (NH4H2PO4) was used as the phosphorus precursor. XRD analysis indicated the formation of compounds with monazite (La, Ce, Pr, Nd) or xenotime (Lu) structures. 31P NMR spectroscopy measurements confirmed that lanthanum formed pure monazite, which indicates a LaCl3  LaPO4 conversion factor near 100 %. These results demonstrate that the stoichiometric addition of NH4H2PO4 is sufficient to obtain quantitative precipitation at 500°C of anhydrous rare earth phosphates in molten LiCl-KCl. The use of this type of precursor, which has the advantage of not modifying the chemical composition of the medium after recovery of the rare earth phosphates, could be considered during the first step of purification of chlorinated baths containing fission products arising from spent fuel reprocessing by a pyrochemical process.