Uranium—Production and Enrichment

Uranium is a widely distributed element in the oxide form, but there are relatively few areas where it occurs in economically recoverable concentrations. Among the major potential sources are Australia, Canada, South Africa, and the Western United States. Recent estimates of the main 

Extent of Australian resources uncertain owing to rapid rate of discovery. 

The higher-grade ore may contain up to 4% of uranium, although mining is carried out down to a concentration of about 0.1 %. In addition to large amounts of uranium in the earth s crust, some 4 x 10 tonnes are estimated to be present in seawater. The concentration of the latter, however, is very low, of the order of 3 parts per billion (ppb), so that recovery will not be economic until a large proportion of the ore reserves has been exhausted. 

To extract the uranium from the ore, the latter is first concentrated by standard metallurgical techniques and then leached in strong acid or alkali. The dissolved uranium is then recovered from the leach solution by solvent extraction or ion exchange. The product, known as yellow cake , contains in the range of 70%-90% uranium oxide, as a mixture of UO2 and UaOg. 

The production of natural or enriched uranium fuel elements, in either metallic or oxide form, requires as an intermediate stage the production of pure uranium dioxide, UO2. By reacting the mixed-oxide concentrate given 

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