Caustic-Side Solvent-Extraction Modeling for Hanford Interim Pretreatment System

Moyer, Bruce A.; Jr, Joseph F Birdwell; Delmau, Lætitia H.; McFarlane, Joanna

doi:10.2172/951061

Cited by 1 publication

(16 citation statements)

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“…[12] The data upon which the present work is based have been tabulated fully in the report literature. [7] The present emphasis builds upon that report in developing a better quantitative understanding of the potassium loading effect on the cesium extraction behavior and gaining a greater level of predictability useful in future extensions of the CSSX process to different feed types not yet assessed experimentally.…”

Section: Introductionmentioning

confidence: 98%

“…[5,6] In this connection, it has been noted that the feed concentration of the chief competing cation, potassium, can have considerable impact when potassium begins to load the calixarenecrown extractant BOBCalixC6 in the currently formulated CSSX solvent, whereupon the cesium distribution ratio D Cs can decrease from the design values of 8-15 to values as low as 3. [7][8][9] This concern has raised questions regarding the applicability of CSSX for the treatment of Hanford tank wastes, known to possess potassium concentrations up to 1 M, [10] much higher than the average concentration of 0.015 M [11] for the Savannah River Site (SRS) waste application for which CSSX was designed. In the present work, it was the goal to explore this question of CSSX performance on the Hanford waste types.…”

Section: Introductionmentioning

confidence: 99%

“…A major function of the IPS will be cesium removal from the waste, for which the CSSX process has recently been considered a candidate technology in contention with resin ion-exchange and fractional-crystallization methods. [33,34] The detailed compositions of the IPS feeds tested here, involving 28 ionic constituents, have been described previously [7] and may be found in an IPS report also. [33] These feeds correspond to the contents of eight doubleshell tanks targeted for the IPS five-year mission.…”

mentioning

confidence: 99%

“…Based on the given detailed feed compositions, we present here the corresponding cesium distribution ratios (D Cs 5 [Cs] org / [Cs] aq ) for the CSSX solvent as calculated using the SXFIT thermodynamic model and as determined experimentally for four of the feeds. [7] A fairly sophisticated computer program, SXFIT, [35] had been successfully used to model the extraction of cesium from the very complicated mixtures present in the SRS tank wastes. [5,6,8] Given that the previous studies had indicated that just four species strongly impact the calculation of the cesium distribution ratios, we also tested the possibility that a simple analog equation might be developed for D Cs prediction.…”

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confidence: 99%

“…The first consisted of 0.020 M BEHBCalixC6 (ChemoDynamics), 0.75 M Cs-7SB modifier, and Hanford compositions from ref. [7] ; Savannah River compositions from ref. [5] .…”

mentioning

confidence: 99%

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Robustness of the CSSX Process to Feed Variation: Efficient Cesium Removal from the High Potassium Wastes at Hanford

Delmau

McFarlane

et al. 2010

Solvent Extraction and Ion Exchange

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This contribution finds the Caustic-Side Solvent Extraction (CSSX) process to be effective for the removal of cesium from the Hanford tank-waste supernatant solutions. The Hanford waste types are more challenging than those at the Savannah River Site (SRS) in that they contain significantly higher levels of potassium, the chief competing ion in the extraction of cesium. By use of a computerized CSSX thermodynamic model, it was calculated that the higher levels of potassium depress the cesium distribution ratio (D Cs ), as validated to within ¡11% by the measurement of D Cs values on various Hanford wastesimulant compositions. A simple analog model equation that can be readily applied in a spreadsheet for estimating the D Cs values for the varying waste compositions was developed and shown to yield nearly identical estimates as the computerized CSSX model. It is concluded from the batch distribution experiments, the physical-property measurements, the equilibrium modeling, the flowsheet calculations, and the contactor sizing that the CSSX process as currently formulated for cesium removal from alkaline salt waste at the SRS is capable of treating similar Hanford tank feeds, albeit with more stages. For the most challenging Hanford waste composition tested, 31 stages would be required to provide a cesium decontamination factor (DF) of 5000 and a concentration factor (CF) of 2. Commercial contacting equipment with rotor diameters of 10 in. for extraction and 5 in. for stripping should have the capacity to meet throughput requirements, but testing will be required to confirm that the needed efficiency and hydraulic performance are actually obtainable. Markedly improved flowsheet performance was calculated based on experimental distribution ratios determined for an improved solvent formulation employing the more soluble cesium extractant BEHBCalixC6 used with alternative scrub and strip solutions, respectively 0.1 M NaOH and 0.010 M boric acid. The improved solvent and flowsheet can meet minimum requirements (DF 5 5000 and CF 5 2) with 15 stages or more ambitious goals (DF 5 40,000 and CF 5 15) with 19 stages. Thus, a modular CSSX application for the Hanford waste seems readily obtainable with further short-term development.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…The first consisted of 0.020 M BEHBCalixC6 (ChemoDynamics), 0.75 M Cs-7SB modifier, and Hanford compositions from ref. [7] ; Savannah River compositions from ref. [5] .…”

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confidence: 99%

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