Uranium
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About Uranium
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In its pure form, Uranium is a silvery white metal of very high density. Uranium
can take many chemical forms, but it is generally found as an oxide - Triuranium octoxide (U3O8).
Uranium is one of the most abundant elements found in the earth's crust. It can
be found almost everywhere, however, concentrated Uranium ores are found in just
a few places, usually in hard rock or sandstone.
URANIUM ORE
URANIUM ATOM
The concentrations of Uranium vary according to the substances it is mixed with
and according to the places where it is found. For example, when Uranium is
mixed with granite that covers 60% of the earth's crust, there are approximately
four parts of Uranium per million, i.e. 999,996 parts of granite and four parts
of Uranium.
The largest deposits of Uranium are found in Canada, Australia and Kazakhstan,
however, high-grade deposits are only found in Canada. The following
illustration shows known conventional resources of Uranium.
YELLOWCAKE
Yellowcake is milled Uranium oxide, known to chemists as U3O8. When Uranium ore
comes out of the mine, it actually contains fairly little of the precious
radioactive element. Though some mines in Canada, the world's leading Uranium
producer, are now yielding ore that contains 20 percent Uranium, lower purity
levels are more typical. Ore that contains less than 1 percent Uranium is not
unusual.
The milling process gets rid of the useless minerals that dominate the ore.
First, raw ore is passed through a series of industrial-sized crushers and
grinders. The resulting "pulped" ore is then bathed in sulphuric acid to leach
out the Uranium. After some drying and filtering, the end product is yellowcake:
a coarse, oxidized powder.
The energy contained in one pound of yellowcake, or U3O8, is equivalent to 31
barrels of fuel oil or 10 tons of coal. A typical pellet of Uranium weighs 7
grams (0.24 ounces). It can generate as much energy as 3.5 barrels of oil,
17,000 cubic feet of natural gas or 1,780 pounds of coal.
Yellowcake is a first step toward enriched Uranium. The powder must still be
converted into Uranium hexafluoride before it can be enriched for ultimate use
by nuclear power plants and weapons manufacturers.
YELLOWCAKE PELLET
URANIUM ENRICHMENT
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