RESEARCH· ·1970·

sample was placed in a glass sample cup, which has a
medimn-fritted glass bottom, and capped with a glass
wool plug. A water-cooled Allihn condenser completed
the extraction assembly.
A bunsen burner was used as a heat source. For solvents
with a high boiling point, such as DMSO, it was
necessary to wrap the outside of the extraction flask
with asbestos tape in order to maintain reflux of the
solvent.
The solvent was then heated to boiling at atmospheric
pressure (approximately 640 millimeters of
mercury) and a moderate reflux from the Allihn condenser
was maintained. The extracted organic material,
which was filtered nearly free of gross inorganic contamination
by the fritted glass bottom of the extractor
cup, was concentrated in the bottom of the extracting
flask.
After an initial extraction during a 10-hour period
the solvent containing the .product was collected and
replaced with fresh solvent. This procedure was repeated
twice more with the same sample so that each
sam pie of ore was extracted three times with a total
of about 90 ml of solvent.
After 200-300 g of ore was treated, the extract was
refiltered through No. 50 Whatman paper to remove any
remaining traces of inorganic contaminants, and all
but about 30 ml of the solvent was removed in a simple
·distillation apparatus. The distillation was carried out
under an inert atmosphere of N2 which swept through
the liquid residue and had the effect of sweeping vapor
from the distilling mixture so that lower residue temperatures
could be maintained. The 20-30 ml of solvent
residue was then diluted with an equal volume of distilled
water. When DMSO was the solvent, the addition
of water caused a dark-brown precipitate to form.
The precipitate was collected by centrifuging, then it
was water washed three or four times or until a clear
supernatant wash was obtained. It was then again
washed in the same fashion using absolute ethanol.
This washing extracted some color from the precipitate,
but most of the precipitate was insoluble in the ethanol.
The washed precipitate was then dried in a vacuum
oven for 10-12 hours at 80°0 and 1 mm Hg.
RESULTS
Some of the solvents were tested because they had
previously been used successfully to extract asphalt,
coallike materials, and humic acids (Degens, 1965).
Others were tested because of their general effectiveness
in dissolving various organic and inorganic materials.
The solvents that were tested were dimethyl
sulfoxide, acetone, n-heptane, benzene, acetic anhydride,
N,N-dimethyl formamide, 1, 2-propandiol
JACOBS, WARREN, AND GRANGER
B185
cyclic carbonate; acetonitrile, 1-methyl naphthalene,
carbon disulfide, toluene, pyridine, piperidine, dietJhy'l
ethyl phosphonate, aqueous sodium hydroxide, and
aqueous hydrochloric acid. The solvent properties of
these rang~ from strongly basic to strongly acidic, and
the boiling points range from about 50°0 to 240°0.
Only two of the solvents-dimethyl sulfoxide
(DMSO) and N,N-dimethyl formamide-had any
measurable effect on the original organic material. The
N,N-dimethyl formamide extracted only a trace of the
original material, but DMSO extracted a fairly large ·
amount of it. Extracted organic material from which
the metals had previously _been removed with hY-drochloric
acid was found to be slightly soluble in 10-
percent aqueous sodium hydroxide.
Extraction of 300 g of ore from the Marquez mine
with DMSO yielded about 2 g of an organic product
which contained both uranium and molybdenum.· The
original ore contained about 1 percent organic carbon,
estimated to indicate about 2 percent organic material.
Therefore, about 30 percent of the organic material
was extracted. A similar extract of ore from the Section
17 mine contained uranium but no molybdenum.
Semiquantitative spectrographic analyses of the DMSO
extracts ·are given in table 1. ·
Most of the metals were removed from the DMSO
extract by leaching with 12M hydrochloric acid for 24
hours. The leached residue, which was dried at 80°0
at 1 mm pressure, was then analyzed (by the Huffman
Laboratories, Wheatridge, Colo.), and it accounted for
98.68 percent of the total weight: 55.31 percent carbon,
TABLE !.-Semiquantitative spectrographic analyses, in parts per
million, of DM so:.extracted organic material
[Analyst: G. W. Sears, Jr.
Element
Si _________________________________ _
Fe----------~-----------------------
~g ________________________________ _
Ca ________________________________ _
Al _________________________________ _
~n----~----------------------------
Ag ________________________________ _
B-------------------------------~--
Ba ________________________________ _
Cr------------~---------------------
Pb gy~~:-~~~===========================
________________________________ _
l] v __________________________________ _
Zn _________________________________ _
B1------------------~---------------
~1o _________ ~-----------------------
Sn _________________________________ _
n.d., below limit of detection]
Section 17
mine ore
extract
1,000
500
50
1,500
n.d.
15
5
5
10
50
300
15
200
20, 000
10
30
n.d.
n.d.
n.d.
Marquez
mine ore
extract
3,000
7,000
300
300
7,000
20
n.d.
n.d.
7
15
15
n.d.
20
1 1, 000
200
n.d.
720
1 10, 000
70
t Oxidation or the DMSO extn).ct at 900°C yielded 16.3 percent ash. X-ray fluorescence
analysis (analyst: J. S. Wahlberg) or the extracted material from the Marquez
mine indicated contents or 11 percent Mo and 1.2 percent U. These results seem more
compatible with the ash content than do the spectrographic analyses.