ORNL-1771 - Oak Ridge National Laboratory

ANP QUARTERLY PROGRESS REPORT
seems that in both systems considerable UF, is
present along with the UF, in a manner such that
it can escape detection by petrographic examination.
UF, in 5inary Alkali-Metal Fluoride Systemno
A number of thermal analyses followed by pefro-
graphic examination of the solid products have
been performed with UF, in each of the NaF-LiF,
NaF-KF, and LiF-KF eutectic mixtures. These
specimens were prepared, in each case, by reducing
the desired UF4-alkali-metal fluoride mixture with
10% excess metallic uranium in nickel crucibles
blanketed with inert gas and fitted with stirrers of
nickel.
In the NaF-LiF system the lowest liquidus tem-
perature observed was at about 630°C at 10 mole %
UF, and 36 mole 96 NaF. In all cases studied (up
to 30 mole 75 UF,) only the free alkali-metal fluo-
rides and the NaF-UF, complex compound (Na,U,F,)
were observed,
In the NaF-KF-IJF, system the red compound
K,IJF, appears a5 the only colored species in
mixtures containing up to 10 mole 96 UF,; the
optical properties are: slightly different from those
of the compound crystallized fromNaF-free mixtures
and may indicate slight solid solution of NaF in
the crystals. Mixtures containing 20 to 40 male %
IJF, show increasing quantities of a blue phase
with optical properties which suggest that it is a
solid solution of Na,lJ,F, and K,U,F,. l-iquidus
temperatures in this system seem io be higher than
700°C in all cases.
Solutions of LIF, in the LiF-KF binary system
show liquidus temperatures in the range 485 to
60Q"C, Petrographic examination of thesenaterials
shows free LiF in 011 specimens, K,LJF, in those
containing less than 10 mole 96 UF,, and K,U,F,
in those containing much above 10 mole % UF,.
Chemical analyses were not performed on any of
these materials, but it is likely that considerable
UF, was present in these specimens, especially tit
the higher temperatures, Additionnl studies of
these potentially valuable systems will be made.
PURIFICAT%ON OF RUBlDllJM FLUORIDE
C. J. Barton, Materials Chemistry Division
D, L. Stockton, QRSQKT
All the rubidium fluoride obtained from commercial
suppliers to date has contained considerably more
than the specified quantity of cesium compounds,
and therefore almost all of it has been returned to
60
the vendors for further processing. However, the
immediate need for small amounts of pure material
for phase equilibrium studies and for rubidium metal
production has necessitated purification of some
material at QRNL.
Experiments16 have shorn the feasibility of
separating rubidium froni cesium with the ion ex-
change medium Amberlite IR-105. This resin was,
accordingly, used in all the experiments conducted.
The resin column consisted of a 3-in.-dia glass
pipe containing a 6-ft bed of the resin. The column
was loaded for each run with about 350 g of crude
RbF known to contain about 20% CsF. Elution of
the rubidium was accomplished in about 35 liters of
0.5 M (NH,),CO, solution; the purity of the product
was not appreciably affected by elution rates in
the range 30 to 60 ml/min.
Elution sf cesium from the column, which was
observed by use of Cs137, required 65 to 70 liters
of the (NH4),C03 solution; elution \NOS not greatly
improved by use of a 1.5 hi solutiori. From a total
of 1775 g of crude RbF charged in five different
runs, somewhat more than 1 kg of RbF containing
less than 1% CsF was obtained. The KF content
(0.6% KF) was not appreciably affected by this
treatment. It is apparent that this purification can
be conducted on a large scale at reasonable cost if
inaterial sufficiently free from cesium cannot be
obtained froni commercial sources.
CHEMlCAL REACTIONS IN MOLTEN SALTS
F. F. Blonkenship L. G. Overholser
W. R. Grimes
Materials Chemistry Division
Cheinicol Equilibria in Fused Salts
J. D. Redrnan C. F. Weaver
Materials Chemi stry Division
'The apparatus and techniques for experimental
determination of equilibrium constants for the
reactions
and
CrO + 2UF,eCrF, + 2UF,
Feo + 2UF4 -+ FeF, + 2UF,
in molten NaZrF, were descri bed previously, l7 and
',I. R. Hiygins, Chemical Technology Division, QRNL,
work lo be published.
17L. G. Overholser, J. D. Kedmoo, and C. F. Weaver,
ANP Quar. Prog. Rep. ,Mm. 10, 1954,ORNL-1692, p 56.