Environmental Engineering Reference
In-Depth Information
Table 11.6
Gamma ray lines
a
in the spectra of the important naturally occurring radionuclides
Number of photons per disintegration
in equilibrium mixture
Bi
214
(Rac)
0.609 0.47
0.769 0.05
1.120 0.17
1.238 0.06
1.379 0.05
1.764 0.16
2.204 0.05
T4
208
(ThC′)
0.511 0.11
0.533 0.28
2.614 0.35
K
40
1.46 0.11
a
With intensities greater than 0.05 photons per disintegration and energies greater than 100 kev
Gamma ray energy (MeV)
Nuclide
Table 11.7
Thorium-
bearing minerals
Name
Composition
ThO
2
content %
Thorium minerals
Cheralite
(Th, Ca, Ce)(PO
4
SiO
4
)
30, variable
Huttonite
ThSiO
4
81.5 (ideal)
Pilbarite
ThO
2
· UO
3
· PbO · 2SiO
2
· 4H
2
O
31, variable
Thorianite
ThO
2
Isomorphous series to UO
2
Thorite
a
ThSiO
4
25 to 63-81.5 (ideal)
Thorogummite
a
Th(SiO
4
)
1-
x
(OH)
4-
x
;
x
< 0.25
24-58 or more
Thorium-bearing min
erals
Allanite
(Ca, Ce, Th)
2
(Al, Fe, Mg)
3
Si
3
O
12
(OH)
0 to about 3
Bastnaesite
(Ce, La)Co
3
F
Less than 1
Betafite
About (U, Ca)(Nb, Ta, Ti)
3
0
9
· nH
2
0
0 to about 1
Brannerite
About (U, Ca, Fe, Th, Y)
3
Ti
5
O
16
0-12
Euxenite
(Y, Ca, Ce, U, Th)(Nb, Ta, Ti)
2
O
5
0 to about 5
Eschynite
(Ce, Ca, Fe, Th)(Ti, Nb)
2
O
6
0-17
Fergusonite
(Y, Er, Ce, U, Th)(Nb, Ta, Ti)O
4
0 to about 5
Monazite
b
(Ce, Y, La, Th)PO
4
0 to about 30; usually 4-12
Samarskite
(Y, Er, Ce, U, Fe, Th)(Nb, Ta)
2
O
6
0 to about 4
Thucholite Hydrocarbon mixture containing U,
Th, rare earth elements
Uraninite UO
2
(ideally) with Ce, Y, Pb, Th, etc. 0-14
Yttrocrasite About (Y, Th, U, Ca)2(Ti,
2
(Ti, Fe, W)
4
O
11
7-9
Zircon ZrSiO
4
Usually less than 1
Source
: After Frondel, C., 1956, in Page, L. R., Stocking, H. E., and Smith, H. D., Jr., U.S. Geol.
Survey Prof. Papers no. 300
a
Potential thorium ore minerals
b
Most important commercial ore of thorium. Deposits are found in Brazil, India, USSR,
Scandinavia, South Africa, and the USA
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