Uranium and Thorium Ores

There are over 100 minerals that contain uranium. Only a few of these are found in deposits that are economically significant. The uranium content of an ore is expressed as a percentage of U3Os and is commonly in the range of 0.1-0.5%, although ores with much higher uranium content have been found. Examples of specific ores are uraninite, which varies in composition from UO2 to UO2 • 2UO3 or U3Os (known as pitchblende), and carnotite (K2O • 2UO3 • V2O5 • xH2O), which, in the past (before 1943), was mined in the United States mainly for its vanadium content. Commercial-grade uranium ores have also been mined in Australia, Canada, China, France, Gabon, Germany, Namibia, Portugal, Russia, South Africa, and the United Kingdom.

Thorium, like uranium, is widely distributed on the earth and is commonly found associated with uranium, but the concentrations of thorium in uranium ores are generally not high enough to be commercially interesting. The principal source of thorium is monazite, (Ce, La, Y, Th) PO4, which occurs as beach and

5The density of soil is typically in the range of 1600-2600 kg/m3.

river sands produced by the weathering of rocks. Significant sources of monazite occur in Australia, Brazil, China, India, South Africa, and the United States (Colorado, Florida, Idaho, Montana, North Carolina, and South Carolina). In the past, monazite was mainly of interest as a source of rare earths and Th02, which was used in gas mantles. The thorium content of monazite is usually in the range of 1-10% Th02.

0 0

Post a comment