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PERIOD ENDPRG DECEMBER 10, 1952
low temperatures (50 to 150 'C), at PURIFICATION OF HYDROXIDES
which a liquid reaction medium was
obtained through the agency of the
low-melting-point polyhydrofluorides
of NaF, or at high temperatures
(550 to SSOOC), at which liquefaction
resulted from the melting of the
NaZrFS appeared feasible. The main
problem was to find the optimum
combination of low- and high-tempera-
ture stages. Earlier results indicated
that a1 though essen ti ally s t oichi -
ometric conversion could he obtained
at low temperatures, complete neutral-
ization and removal of water was best
ensured by high-temperature treatment
of the molten salt. Accordingly, all
trials were finished withat least 1 h r
of high- temperature treatmen t.
Difficulties associated with the
appearance of insoluble intermediates
were encountered at both low and high
temper a tu res. Cemen ts , p r e sumably
related to ZrOF2, were developed in
the partly r~acted mixtures; rapid
passage of HFor helium was ineffective
in mixing the cemented portions, and
charin el ing occur red.
Successful results were achieved
if long soaking periods (12 to 16 hr)
at low temperatures were used, followed
by high - temperature hydrofluo rinati on ;
when 25% of the charge material was
the previously prepared NaZrF,, the
high- temperature treatment alone was
sufficient. Both petrographic exami-
nation and x-ray analysis indicate
that even in those samples in which
the material balance is 100% there
occurs a trace amount of Na2ZrF6, and
as a result the refractive index or
the x-ray crystal pattern deviates
slightly from the exact standard for
NaZrF,.
E. E. Ketchen L. G. Overholser
Materials Chemistry Division
The purification of hydroxides has
continued, but at a further decreased
rate. An increased interest in
handling alkali metals, especially the
alloy NaK, made it necessary to
condition the vacuum dry box and
perform numerous loadings and un-
loadings, which cut heavily into the
time allotted for hydroxide purifi-
cation. However, sufficient NaQH has
been puri fled to maintain an inventory
large enough to fill all requirements
for this material.
'I'he method previously
which involves the removal of Na2C0,
from a 50 wt % solution of NaOH and
subsequent dehydration at 45OOC under
vacuum, was used for all NaOH purifi-
cation. Nine batches averaging
1 1/2lh Der batch were prepared during
the period. The purified product
continues to mee t the specification of
0. 1 w t 7% for both Na2C0, and H,O.
Additional pure KOH has been prepared
by the method previously desc~ 1 hed;' l3,I4)
namely, the interaction of pure
potassium with water, followed by
dehydration at 45Q'C under vacuum.
The K2C0, content has ranged from
0.04 to 0. 12 w t % and the water
content has been 0,l w t % or less,
Approximately 2 lb of KOH wab prepared
during the period, and the inventory
was thus increased to about 5 pounds.
A t present, the demand for pure KOH
is virtually nonexistent, and unless
some unforeseen demand arises it is
not planned to react more than an
additional pound of potassium.
Two batches of Sr(OH), were purified
The feasibility of making Z~F, by the method previously described
directly from ZrOz and NaF has been
(13)E. E. Ketchen and L. G. Overholser, ANP
demonstrated from a laboratory stand- Quar. Prog. Rep. June 19, 1952, OWL-1294, p. 89.
point; the practical application of
theProcess requires further engineering
(I4)D. R. Cuneo, E. E. Ketchen, D. E. Nicholson,
and L. C, Overholser, AN^ Qua.. prog. Repa March
d ev e 1 o pmen t . 10. 1952, ORNL-1227. p. 104.
125