Extraction DIAMEX

FIGURE 7.3 Osmolality/molarity versus molarity plots for the DMDBTDMA, ra-dodecane system contacted with water at 60°C. (From L. Martinet, Organisation Supramoleculaire des Phases Organiques de Malonamides du Precede d Extraction DIAMEX. PhD thesis. Rapport CEA-R-6105, 2005. With permission.)... 

Table 12.11 Decontamination Factors for Extraction (Mass in the Feed to Mass in Raffinate) and for the Stripping [(Mass in the Feed Minus Mass in the Raffinate)/Mass in the Organic Out] in DIAMEX Hot Test with Flow Sheet in Fig. 12.13...

Berthon, L., Martinet, L., Testard, F., Madic, C., Zemb, T. 2007. Solvent penetration and sterical stabilization of reverse aggregates based on the DIAMEX process extracting molecules Consequences for the third phase formation. Solvent Extr. Ion Exch. 25 (5) 545-576. 

Charbonnel, M.C., Berthon, L. 1997. Optimization of the extractant molecule for the DIAMEX process. In Rapport Scientifique de la Direction du Cycle de Combustible (DCC). Report CEA-R-5801, pp. 114-119. 

Modolo, G., Vijgen, H., Serrano-Purroy, D. et al. 2007. DIAMEX counter-current extraction process for recovery of trivalent actinides from simulated high active concentrate. Sep. Sci. Technol. 42 (3) 439-452. 

Berthon, L., Morel, J.M., Zorz, N. et al. 2001. DIAMEX process for minor actinide partitioning Hydrolytic and radiolytic degradations of malonamide extractants. Sep. Sci. Technol. 36 (5 6) 709-728. 

Erlinger, C.V. 1998. Towards a physical interpretation of third phase formation in liquid-liquid extraction. Application to the DIAMEX process for the treatment of high radioactive nuclear wastes. Thesis. University Paris XI, Paris. 

Heres, X., Ameil, E., Martiniz, I., Baron, P, Hill, C. 2007. Extractant separation in DIAMEX-SANEX process. GLOBAL 2007, Boise, ID, September 9-13. 

Bidentate oxygen-donor extractants include the neutral diamide compounds, such as the malonamides used in the French DIAMEX and DIAMEX-SANEX processes, RR N(C=0)-CHR"-(C=0)NRR the bisphosphine oxides, RR (P=0)- CIIR"-(P=0) RR the carbamoyl-(methyl)-phosphinates, R0R 0(P=0)-(CI I On o 0rr(C=0)NRR or the more efficient carbamoyl-methyl-phosphine oxides, RR (P=0)-CHR"-(C=0)... 

There are various types of organic proton exchangers (34, 35, 38). Diesters of phosphoric acid, (RO)2P = 0(0H), phosphonic acids, R(RO)P = 0(0H), and phos-phinic acids, R2P = 0(0H), where R represents linear or branched alkyl or phenyl substituents, are the most common cation exchangers developed in liquid-liquid extraction for the extraction of trivalent 4/and 5/elements. They were initially developed for the American TALSPEAK and the Japanese DIDPA processes and have recently been introduced in the French DIAMEX-SANEX process. As for previously described NOPCs, these organophosphorus acids present oxygen-donor atoms (hard bases) in their structures and therefore will easily coordinate trivalent lanthanide and actinide cations, but they will not allow complete discrimination of the two families of elements. However, contrary to previously described neutral organophosphorus... 

Second, as a solvent recycle process, which ran for 54 hours without solvent clean-up to treat 3.85 L of a DIAMEX An(III) + Ln(III) product. This second hot test, which generated 6.5 L of Am(III) + Cm(III) product, revealed partial degradation of t Pr-BTP, probably because of alpha/gamma radiolysis reflected by a 40% decrease in the solvent-extraction performance observed after two cycles (207). 

The DIAMEX-SANEX/HDEHP process is probably the only single-step process that enables a complete selective An(III)/Ln(III) partitioning from non-pretreated PUREX raffinates (245). It combines two organic molecules possessing opposite but complementary extracting mechanisms ... 

V,. V -l )imethyl-/V,/V -dioctyl hcxylcthoxymalonamidc, used in the DIAMEX process, which extracts trivalent metallic cations from highly acidic feeds by solvation, thus avoiding any adjustment of the acidity of PUREX raffinates. 

As in the SETFICS and TALSPEAK processes, the DIAMEX-SANEX/HDEHP process involves selectively back-extracting the trivalent actinides by a hydrophilic polyamino-carboxylate complexing agent, HEDTA, in a citric acid buffered solution (pH 3). However, the combination of HDEHP and DMDOHEMA at high acidity promotes the coextraction of some block transition metals, such as Pd(II), Fe(III), Zr(IV), and Mo(VI), which must be dealt with by specific stripping steps (as described on Figure 3.26) that increase the total volume of the output streams ... 

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