Cleanex process

Bigelow, J. E. Collins, E. D. King, L. J. "The "Cleanex" Process A Versatile Solvent Extraction Process for Recovery and Purification of Lanthanides, Americium, and Curium," Actinide Separations, ACS Symp. Series, No. 117, 1980, 147-155. 

The Cleanex process was adapted from the DAPEX process described in Section 65.2.2.1 (iv) and also utilizes HDEHP to coextract the lanthanides and transplutonium elements. Subsequent separation of these two groups may then be carried out using, for example, the Tramex process. ... 

The Cleanex Process A Versatile Solvent Extraction Process for Recovery and Purification of Lanthanides, Americium, and Curium... 

The chemistry, reagents, equipment, and basic operations relating to the Cleanex process and typical results obtained with the Cleanex process are covered in the sections below. 

The equipment typically used at TRU for carrying out the Cleanex process batchwise is illustrated schematically in Figure 1. The operating technique and design considerations for some of the items in Figure 1 have been more fully described by Chattin ( 3). ... 

In the environment of the TRU Facility at ORNL, the Cleanex process has proved to be extremely valuable and is routinely relied upon to perform a variety of separations and purifications. 

Since numerous temporary piping connections are made to accommodate multipurpose use of several tanks during a campaign, leaks and/or small spills can occur. Thus, the cell cubicle floors and external portions of the equipment are flushed thoroughly after each campaign. All of the rework materials obtained between campaigns are accumulated, processed by means of one or two cycles of the Cleanex batch extraction process to remove miscellaneous impurities, and recycled to the next campaign. 

A typical composition of feed solution and the fractional distribution of the feed solution components into the various exit streams are shown in Table I. The feed solution is usually the product of a Cleanex batch solvent extraction ( T0), a process... 

The acid dependency observed in practice hal been only approximately inverse third power. Impurities in Cleanex feed solutions often cause a departure from ideality (e.g., by common-ion effect or by consumption of some of the HDEHP), and we have not been able to control the extraction of the actinide elements solely by monitoring the aqueous-phase acidity. Fortunately, when processing transplutonium elements, the high specific activity of 21+I+Cm facilitates the detection of that isotope in both phases, thus permitting a rapid determination of the degree of extraction. The extraction coefficients of the trivalent actinides and lanthanides are all quite similar, so the 21+1+Cm serves as an excellent marker for all the extracted ions. 

Table I. Typical Composition of Cleanex Feed Solutions When Processing Transplutonium Elements During a HFIR Target Campaign...

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