Chemical Processing Department Monthly Report: July 1957 Page: 83 of 107
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Research and Engineering HW-51802
PROCESS CHEMISTRY OPERATION.
PROCESS ASSISTANCE
Purex Process Studies
The recovery problem which arose when approximately 64 liters of organic con-
taining 10 kg of plutonium were accumulated following inadvertent concentra-
tion of solvent in the plutonium concentrator has received laboratory attention
directed toward the development of a process for recovering the plutonium in
Recuplex. Since the bulk of the organic was assumed to be dibutyl phosphate
(DBP), which strongly complexes plutonium(IV) and (VI) but does not complex
plutonium(III), it was tentatively planned to blend the organic with solvent
and strip the plutonium out as plutonium(III) with a reducing agent.
laboratory experiments with this organic (diluted 10 to 100-fold with 15%
TBP in CC14) indicated that exhaustively stripping it with a reducing agent
alone will recover only 80 to 90 per cent of the plutonium. The recovery was
limited by plutonium extraction coefficients (E$) of greater than 10 after the
first few stripping stages, and varied only slightly with different reducing
agents. Apparently, the large excess of DBP over the plutonium prevented
further reduction to plutonium(III). In a variation of this procedure, it was
found that addition of zirconium(IV) to the reducing agent in an amount
slightly in excess of that required to complex the DBP permitted the remainder
of the plutonium to be reduced. - In this instance, the measured plutonium Ea,
with 3 M HN03, 0.05 M Fe.3, and 0.3 M Zr44 in the stripping solution was less
than 0.1 and remained constant through several successive contacts of the
organic with fresh stripping solution. Greater than 99.9 per cent plutonium
recovery was demonstrated by this procedure. Though direct analyses were not
made, it was inferred from the results of the tists that the DBP concentra-
tion in the organic was 3 to 5 M and the oxidizing normality was 1.5 to 2.
This procedure for recovering plutonium complexed with DBP by reducing the
plutonium in the presence of zirconium ion may be applicable to the Purex HC
or 1BX Columns when processing backcycled 2WW, which frequently contains DBP.
Additional work was done to characterize the effect, on plutonium loss to
the BCW, of H2S04 addition to the HCX. By means of the plutonium retention
test, whereby a tixed amount of plutonium is extracted into the solvent and
then removed by three successive stripping contacts, it was shown that the
plutonium retained in 100 with 0.005 M H2S04 as the strip was 20 to 30 per cent
of that retained using 0.01 M HNO3, with or without uranium present. With 30%
TBP spiked with 0.05 g/l DBP, the plutonium retention with the H2S04 strip was
0.5% of that with 0.01 M ENO ; with a chemically-degraded diluent spike, the
plutonium retention with H2S was 30% of that with ENO3.
Mzrcuric ion has been reported to catalyze t e degradation of Amsco 125-82 in
contact with 10 M HN3 (ORNL-1610). 5 x 10' molar mercuric ion is currently
added to Purex dissolver solution to inhibit iodine evolution. In a laboratory
check of the effect of mercury under Purex conditions, no degradation of 30%
TBP in Shell E-2342 diluent could be attributed to mercuric ion concentra-
tions as high as 0.1 M in 95 hour contacts of the solvent with 2 M HN03 at 40 C
J-1 0 LA f
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Hanford Atomic Products Operation. Chemical Processing Department. Chemical Processing Department Monthly Report: July 1957, report, August 22, 1957; Richland, Washington. (https://digital.library.unt.edu/ark:/67531/metadc1312193/m1/83/: accessed April 18, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.