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Fig. 11.3 Uranium resources and inferred potential reserves as estimated by the program
MI M IC (Brinck 1974 ). Numbers along diagonal refer to largest possible deposits for given values
of x and d . Dollar values refer to estimated average exploitation costs
Figure 11.3 (modified from Brinck 1974 ) is a worldwide synthetic diagram for
uranium with average crustal abundance value set equal to 3 ppm and dispersion
index d
0.2003. This diagram is equivalent to a cumulative frequency distribution
plot with two logarithmic scales. Value (ppm U) is plotted in the vertical direction
and weight (tonnes U) is plotted in the horizontal direction. All weight values are
based on cumulative frequencies calculated for the logbinomial distribution and are
fully determined by the mean and coefficient of dispersion. The diagram shows
curved lines of equal metal content. In 1971 it was, on the whole, profitable to mine
uranium if the cost of exploitation was less than $6.00 US per pound U 3 O 8 .
Individual orebodies can be plotted as points in Fig. 11.3 . In 1971 such deposits
would be mineable if their point would fall within the elliptical contour labeled
$6.00. The other elliptical contours are for uranium deposits that would have been
more expensive to mine.
Later applications of Brinck's geochemical crustal abundance approach include
Ruzicka ( 1976 )andGarrett( 1986 ). These authors used other methods for estimating
the maximum number of subdivisions of the environment ( N ). In his study of
sedimentary uranium deposits, Ruzicka ( 1976 ) based the estimate of N on
sedimentological considerations assuming that the environment had been sorted
naturally into small homogeneous domains. Garrett ( 1986 ) estimated N from
maximum “barrier” concentration values chosen for chemical elements in particular
deposit types or regions. Both authors acknowledged that estimating the number of
subdivisions ( N ) constitutes a major problem in applications of Brinck's approach
(also see Harris 1984 , Chap. 8, pp. 184-222).
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