mdp.39015006050176-31
Click here to load reader
-
Upload
muhammad-tariq -
Category
Documents
-
view
212 -
download
0
Transcript of mdp.39015006050176-31
URANIUM OKE PROCESSING
9
in equilibrium with the radium-group metals (those in the decay series
from Ra226 to Pb206), about 40% of the beta-ray intensity originates from
the uranium-group metals, but only about 2% of the gamma-ray in-
tensity. If one-half of the quantity of each isotope of the radium group
were removed, the total relative gamma intensity would be 51% of what
it woidd be in the case of equilibrium. This includes 2% from the ura-
nium group and 49% from the part of the radium group that remains.
Accordingly, the disequilibrium-correction factor based on gamma-ray
intensity measurements would be 100 4- 51, or 1.96; but the disequi-
librium-correction factor based on beta-ray measurements would be 1.43.
It is therefore generally simpler not to use beta-gamma sensitive radio-
metric equipment for assaying, but to use equipment for measuring
only one type of activity both in the mine and in the laboratory. Usually
gamma-only radiometers are the most convenient.
One difficulty in radiometric assaying is due to the changes in activity
occurring as the result of the loss of radon-222, a radioactive gas, during
ore grinding. One solution is to seal a sample after pulverizing and then
to wait 20 or 30 days for the radon to build up to an approximate equi-
librium amount. The waiting time can be shortened to approximately
one-tenth of the 20 or 30 days if two apparent assay values are taken with
an intervening period of only a few days. The first assay should be at
least four hours after sealing. The correct assay can be estimated by
use of the following formula:
True %e UA = Ai + f(M) (At - Ax)
where %e U308 = the % of U308 that would be present if the uranium
were all present in hat form; Ai = the first apparent assay, in terms of
%e U808; A2 = the second apparent assay, also as %e U308;
= 1/(1 — e~XAt); X = decay constant of radon (0.1812/day); and A/
= the lapsed time interval in days.
The upper limit of error associated with the use of this radon-loss
correction formula is
%t =— -(1 + e-2XA')1/2/(l - e-™)-100
n
where n is t he number of random pulses counted over a period of time
Dry Physical Processing of Uranium Ores and Compounds
Various uranium ore processing mills, particularly the small ones, are
ordinarily set up to handle one particular type of ore, and cannot take
Genera
ted o
n 2
01
3-0
8-2
9 1
5:5
7 G
MT /
htt
p:/
/hd
l.hand
le.n
et/
20
27
/mdp.3
90
15
00
60
50
17
6Public
Dom
ain
, G
oog
le-d
igit
ized
/
htt
p:/
/ww
w.h
ath
itru
st.o
rg/a
ccess
_use
#pd-g
oogle