Sodium diuranate or yellow uranium oxide, Na2U2O7·6H2O, is a uranium salt also known as the yellow oxide of uranium. Sodium diuranate is commonly referred to by the initials SDU. Along with ammonium diuranate it was a component in early yellowcakes. The ratio of the two species is determined by process conditions; however, yellowcake is now largely a mix of uranium oxides. It was also used in porcelain dentures to give them a fluorescence similar to that of natural teeth and once used in pottery to produce ivory to yellow shades in glazes. It was added to these products as a mix with cerium oxide. The final uranium composition was from 0.008 to 0.1% by weight uranium with an average of about 0.02%. The practice appears to have stopped in the late 1980s.
|Melting point||1,646 °C (2,995 °F; 1,919 K)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
In the classical procedure for extracting uranium, pitchblende is broken up and mixed with sulfuric and nitric acids. The uranium dissolves to form uranyl sulfate, and sodium hydroxide is added to make the uranium precipitate as sodium diuranate. This older method of extracting uranium from its uraninite ores has been replaced in current practice by such procedures as solvent extraction, ion exchange, and volatility methods.
Sodium uranate may be obtained in the amorphous form by heating together urano-uranic oxide and sodium chlorate; or by heating sodium uranyl acetate or carbonate. The crystalline form is produced by adding the green oxide in small quantities to fused sodium chloride, or by dissolving the amorphous form in fused sodium chloride, and allowing crystallization to take place. It yields reddish-yellow to greenish-yellow prisms or leaflets.
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- "Uranium Containing Dentures (ca. 1960s, 1970s)". Retrieved 2016-06-01.
- "MQes Uranium Inc". Retrieved 2016-06-01.