Determination of rare earth elements in uranium compounds

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Material Information

Title:
Determination of rare earth elements in uranium compounds
Series Title:
United States. Atomic Energy Commission. MDDC ;
Physical Description:
4 p. : ill. ; 27 cm.
Language:
English
Creator:
Hirt, R. C
Nachtrieb, N. H
Los Alamos Scientific Laboratory
U.S. Atomic Energy Commission
Publisher:
Technical Information Division, Oak Ridge Operations
Place of Publication:
Oak Ridge, Tenn
Publication Date:

Subjects

Subjects / Keywords:
Uranium compounds   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliography references.
Statement of Responsibility:
by R.C. Hirt and N.H. Nachtrieb.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 005023686
oclc - 277230291
System ID:
AA00009407:00001


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MDDC 903
(LADC 274)


UNITED STATES ATOMIC ENERGY COMMISSION







DETERMINATION OF RARE EARTH ELEMENTS IN URANIUM COMPOUNDS



by
R. C. Hirt
N. H. Nachtrieb


Los Alamos Scientific Laboratory


Date of Manuscript:
Date Declassified:


June 24, 1944
January 31, 1947


This document is for official use.
Its issuance does not constitute authority
for declassification of classified copies
of the same or similar content and title
and by the same authors.




Technical Information Branch, Oak Ridge, Tennessee
AEC, Oak Ridge, Tenn., 4-11-49--750-A4418


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DETERMINATION OF RARE EARTH ELEMENTS IN URANIUM COMPOUNDS


By R. C. Hirt and N. H. Nachtrieb


ABSTRACT

The separation of the "rare earth" elements from uranium and its compounds may be obtained
by means of an ether extraction, precipitation as fluorides, and purification by way of the hydroxides.
The final determination is carried out spectrographically, using a Jarrell-Ash Wadsworth Spectro-
graph and an A.R.L.-Dietert Multisource. Dysprosium, gadolinium, samarium, neodymium, praseo-
dymium, lanthanum, and cerium were investigated, and their limits of sensitivity and their recoveries
from U3Odetermined. The method may be applied to other "rare earth" elements as well.

The procedure used for the separation of the rare earth elements from uranium compounds was
that given by H. G. Short and W. L. Dutton in BM -325, with certain modifications to obtain more thor-
ough separations. Greater sensitivities were obtained by use of a condensed discharge from an A.R.L.-
Dietert Multisource instead of a DC arc, and by use of a Dietert Projection-Comparator Densitometer
for measuring the relative transmissions of the lines from samples and those of a standard plate.


SPECTROGRAPHIC DETERMINATION OF RARE EARTH ELEMENTS

The spectrographic determinations were carried out with a Jarrel-Ash Wadsworth Automatic
Spectrograph having a dispersion of 5.27 A/mm. The electrodes were placed 45 cm from the slit,
with a 90 mm spherical quartz lens 37 cm from the slit. The slit opening was 35 microns wide and
2 mm high. Eastman Spectrum-Analysis No. 1 plates were used for photographing the region from
2100 A to 4800 A.

Standard solutions of Dy, Gd, Sm, Nd, Pr, La, and Ce of a concentration of 100 micrograms/ml
were prepared. These solutions were diluted to make standard solutions of concentrations of 10y /ml
and y /ml. Suitable amounts of these solutions were evaporated on 6 mm diameter copper electrodes,
on a flat surface freshly cut by a lathe. These were made the bottom electrodes in the spark.
An A.R.L.-Dietert Multisource operating off a 230-volt AC line at 19 amperes (primary) was
used. 60 microfarads of capacity, 25 microhenries of inductance, and 25 ohms of resistance were in-
troduced in the spark circuit. The spark operated at 920 volts, with a 10,000 volt initiator. Expo-
sures were for 40 seconds. The resulting spark was found to be quite stable, and the exposure repro-
ducible.
The S.A. No. 1 plates were developed in Eastman D-19 developer for 3 minutes, placed in an
acetic acid short-stop bath for 10 seconds, and fixed in an Agfa acid hypo bath for 3 minutes. The
plates were dried in a stream of warm air.
A standard plate was made up using 5, 2, 1, .5, .2, .1, .05, .02, .01, and .005 micrograms of each
element. The selected lines were photometered on an A.R.L.-Dietert Projection-Comparator Densi-
tometer, and the percentage-transmission vs quantity curves plotted. The plates from samples were
treated in the same way, and the measured transmissions compared with the graph from the standard
plate to determine the amount of the element in question that was present in the sample.


MDDC 903






MDDC 903


SENSITIVITIES

The limit of detectibility for each rare earth element tested is given in Table 1.

Table 1.

Limit of Detectibility
Element Micrograms Parts per million
(10 gm sample)

Dy .05 .005
Gd .05 .005
Sm .50 .050
Nd .20 .020
Pr .10 .010

La .01 .001
Ce .10 .010



CHEMICAL SEPARATIONS

a. The procedure given below is essentially that developed by Short and Dutton in BM-325.
Advantage is taken of the solubility of uranyl nitrate in ether to separate the bulk of the uranium from
the rare earth elements. The rare earths are precipitated as fluorides, and purified again by a pre-
cipitation as hydroxides to remove Al, Mg, and the last traces of uranium. Details of procedure are
not given here; see BM-325.
b. Modifications of method of BM-325
1) Three ether-water extractions in place of two.
2) Fluoride precipitate after ignition twice treated with hot concentrated BSO,.

3) Several rinsings (as many as 5 or 6) of the precipitated hydroxides with 5% NIlOH, found
necessary to remove last traces of uranium to prevent the uranium lines ("background") from ob-
scuring rare earth lines. Rinsings carried out until no yellow color could be detected on filter paper.
4) If multiple rinsings failed to remove yellow color, the precipitate was redissolved in HC1,
and another precipitation of hydroxides carried out.


WAVELENGTHS USED FOR ANALYSIS

Table 2 gives the various lines used in the spectrographic analysis, together with their limits of
detectibility and coincident lines. The lines listed which do not have as low a limit of detectibility as
the most sensitive lines are used as confirming lines and are also useful when larger amounts of the
element are present.

RECOVERIES

Various known amounts of the rare earth elements were added to 10-gram samples of UOa
These samples were subjected to the separation procedure, and the rare earths analyzed spectro-
graphically. Table 3 shows typical recoveries. All samples were 10-grams unless otherwise marked.







MDDC 903


Sample (U, U3O, etc.)
+ HNO,
Uranyl nitrate
Sevap. to dryness
+ ether
| (three extractions with 1 ml water)


Water layer
(contains rare earths,
some U, etc.)
4 dissolved in HNO,
pp't by HF
*'


Filtrate
(contains U)
rejected


Ether layer
(contains bulk of uranium)
rejected


precipitate
(rare earths+Ca+AI+ some U)
evaporated with HSO4 to remove F
redissolved in HCI,
ppt with NH, OH + salicylic acid
I (wash ppt several times)


ppt rare earth hydroxides
dissolved in HC1
evaporated on electrode


filtrate
Ca, Al, and i


Table 3.

Element Micrograms Micrograms Remarks
added recovered


not accurate above 5 micrograms




not accurate above 5 micrograms




not accurate above 5 micrograms


limit of detectibility .5
not accurate above 5 micrograms


in 10 milligram sample

in 10 milligram sample


5 to 10
3 to 5
1
.3 to .5
5 to 10
4.5 to 5
1
.4 to .5
5 tolO
4.5to 5
.8
less than .6
5 to 10
4 to 5
.7to 1
.3 to .5
1.2to 2
1.5to 2
.8 to 1
2
.7 to 1







MDDC 903


Table 2.

Element Wavelength Detectibility Coincident Lines
(micrograms)


3531.71
3577.99
3407.80

3538.52
3393.58


3422.47
3100.51
3362.24
3350.10
3481.82

3592.59
3745.62
3634.27
4256.40
3568.26

4012.25

3851.75
4303.57
3863.41
4156.08

4100.75

4008.71
4179.42
4118.48
4189.52
3949.11

3988.52
3871.63
3794.77
3790.82
4151.97
4012.39

3801.53
4137.65
4186.60


3531.85
3577.87
3407.60

3538.75
3392.98


3531.71
3577.88
3407.46
3408.13
3538.24
3392.66
3393.84

3422.66
3100.30
3361.92
3350.21
3482.19
3592.59
3745.56
3634.70
4256.48
3567.84
4011.68
4011.97
3851.62
4302.89
3863.40
4155.58
4099.54
4101.77
4009.71
4179.26
4118.55
4191.08
3948.78
3949.59
3987.99
3871.75
3795.00
3790.51
4151.96
4012.25
4013.82
3801.00
4136.45
4186.81
4184.25


3863.39
4156.24
4100.92
4102.38
4008.93
4179.51
4118.54
4191.44
3949.44
3949.96
3989.72
3872.12
3796.39
3790.84
4152.58
4012.47


4137.10
4187.04
4184.90


END OF DOCUMENT


Cr 3422.74
Fe 3100.67


Zr 3481.15
Gd 3592.70
V 3745.80
Mo 3635.14



Ce 4012.39

Fe 3852.57








































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