Flowsheet scrub solutions

The second flowsheet was therefore implemented in 24 stages (Figure 3.13) (177). This time, the An(III) + Ln(III) product solution contained only 0.66% Sr and 1.31% Mo. However, the large amounts of oxalic acid (up to 0.4 M) introduced in the feed and scrubbing solutions to avoid Zr extraction led to partial precipitation of An(III) and Ln(III) oxalates in the low acidity conditions of the stripping section. 

Figure 6. Conceptual flowsheet for the recovery of actinides from TBP-Na2COs scrub solutions basis one MTHM.

The solution involves the use of two water substreams for scrubbing at 293 and 298 K. The first coolant is employed to undertake the cooling duty. Several conceptual flowsheets can be developed to implement this solution. Figures 9.18a and b illustrate such configurations. The developed mass exchanger is composed two sections. The top section employs Si,3 to reduce the ammonia composition in the gas from 0.13% to 0.10% and operates at an average water temperature of 293 K. In Fig. 9.18a, temperature is reduced by indirect contact cooling of the... 

Although solvent samples have been observed for approximately one year without any solids formation, work was completed to define a new solvent composition that was thermodynamically stable with respect to solids formation and to expand the operating temperature with respect to third-phase formation.109 Chemical and physical data as a function of solvent component concentrations were collected. The data included BC6 solubility cesium distribution ratio under extraction, scrub, and strip conditions flowsheet robustness temperature range of third-phase formation dispersion numbers for the solvent against waste simulant, scrub and strip acids, and sodium hydroxide wash solutions solvent density viscosity and surface and interfacial tension. These data were mapped against a set of predefined performance criteria. The composition of 0.007 M BC6, 0.75 M l-(2,2,3,3-tetrafluoropropoxy)-3-(4-.sw-butylphenoxy)-2-propanol, and 0.003 M TOA in the diluent Isopar L provided the best match between the measured properties and the performance criteria. 

Fig. 9.1. Single contact H2SO4 making flowsheet. SO3 rich gas from catalytic SO2 oxidation is reacted with strong sulfuric acid, Reaction (1.2). The reaction consumes H20(f) and makes H2S04(f), strengthening the acid. Double contact H2SO4 making is described in Fig. 9.6. A few plants lower the SO2 content of their tail gas by scrubbing the gas with basic solution (Hay et al., 2003).

Flowsheet Testing. Na2C03 scrub waste solutions were prepared by extracting measured amounts of U(VI) and Pu(IV) into dodecane solutions containing 0.02 M - 0.04 M HDBP and 0.0067 M -0.0134 M H2MBP. The resultant organic phase plus precipitates were then slurried with the required amount of Na2C03 until all the precipitate dissolved. 

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