TBP process

Degraded TBP process solvent is typically cleaned by washing with sodium carbonate or sodium hydroxide solutions, or both. Such washes eliminate retained uranium and plutonium as well as HDBP and H2MBP. Part of the low-molecular-weight neutral molecules such as butanol and nitrobutane, entrained in the aqueous phase, and 90-95% of the fission products ruthenium and zirconium are also removed by the alkaline washes. Alkaline washing is not sufficient, however, to completely restore the interfacial properties of the TBP solvent, because some surfactants still remain in the organic phase. 

In the TBP process, which was developed in the USA283 and in England,286 zirconium(IV) hydroxide (produced, for example, by the hydrolysis of the material obtained from the caustic fusion of zircon sand) is dissolved in nitric acid to give a solution containing 30-100 g of zirconium (plus hafnium) per litre and 5-8 M free nitric acid. The zirconium is extracted into a 50-60% solution of TBP in a suitable hydrocarbon diluent, the loaded organic phase is washed in 5 M nitric... 

Modolo, G., Asp, H., Vijgen, H. et al. 2007. Demonstration of a TODGA/TBP process for recovery of trivalent actinides and lanthanides from a PUREX raffinate. GLOBAL 2007, Boise, ID, September 9-13, pp. 1111-1116. 

The Talspeak process and the CEN-FAR TBP process were transposed to extraction chromatography. European researchers (6) have adapted the Talspeak process for the final purification of 2l+1Am and 2l+,+ Cm at the scale of a few grams. Hence our intention is to use this experiment to treat hot targets. 

CEN-FAR TBP process a chromatographic separation process includes three successive stages for which the chemicals conditions are to be determined fixation, scrubbing and elution. 

The good performance levels obtained with this TBP process let us to select it to develop a process applicable to the treatment of industrial targets. 

The treatment of irradiated plutonium targets by extraction chromatography allowed the purification of the isotopes 2l 3Am and 2I+I+Cm on the scale of few tens of grams. This process proved to be extremely simple and flexible, and yielded results which are reproducible in time. The chief advantage of the TBP process over the HDEHP process in high and medium activity conditions lies in the... 

The concentration of HAW raffinates and the addition of suitable amounts of nitrate salts are therefore the key steps on which the applicability of the TBP process for partitioning purposes is based. 

Results obtained from denitration tests performed on a concentrated synthetic HAW solution (500 l/ton U) as proposed in the TBP process scheme (option 2), were comparable to those discussed above. The experiments were so far done on simulated HAW solutions. Active runs are scheduled for the second half of 1979. 

Also in the case of the TBP process, only simulated HAW solutions have been until now used to study the process feasibility. Results have already been reported (9), which indicated that separation yields of about 99.9% can be obtained for Am after three successive extraction stages operating with a concentrated HAW solution adjusted to 0.1 — 0.2 M HN03, 0.65 M AI(N03)3 and 1.3 M NaN03. The back-extraction of all the actinides and RE from loaded TBP (30% in n-dodecane) was carried out by means of Na5 DTPA-glycolic acid solution which can be then used directly to separate Am and Cm from RE according to the Talspeak process (15). 

The HDEHP process. Conceptually this process is very similar to the TBP process as Fig. 2 shows. Therefore only the main differences are pointed out here. They concern ... 

Richardson, G. L. The Effect of High Solvent Irradiation Exposure on TBP Processing of Spent LMFBR Fuels , HEDL-TME 73-51, 1973 Appendix A. 

New TBP process. The introduction of a more elegant multi-stage counter-current TBP extraction process at Springfields was delayed because of the successful operation of the ether process. Although ether is a potentially hazardous solvent, precautions were always adequate to prevent com-... 

A similar 40 per TBP process is also used at Bouchet in France. Two packed columns are used with Raschig ring packing, each 5 m in height, one for extraction into the solvent and the other for backwashing. Further purification is necessary, e.g. by peroxide precipitation, presumably because a stripping section is not employed in the primary extraction column. 

In general, satisfactory separation is obtained from iron, manganese, titanium and tin impurities in the TBP processes. Mixer-settler plant can be used, but is best constructed of, or lined with, polythene, because of the high concentrations of hydrofluoric acid which are necessary. 

The most important TBP process is the PUREX process, in which 20—40 vol/% TBP in the hydrocarbon diluent is used. The flowsheet commonly used in the United States specifies 30 vol/% TBP (Long, 1978). A typical American flowsheet is shown in Figure 14.14. Uranium is extracted from the feed and decontaminated in the first contactor, separated from plutonium in the second contactor, and stripped back into an aqueous phase in the third contactor. A high aqueous phase to organic phase flow ratio... 

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