Pitchblende partial oxidation

Most natural uraninites or pitchblendes (and probably coffinites) are partially oxidized, with compositions between UO200 and UO267 (tl30g) (cf. Giblin 1987 Ahonen et al. 1993 Sunder et al. 1994). The stabilities of oxide phases of mixed oxidation state (between IV and VI) are shown in... 

Direct alkali leaching of uranium alone is used in the Eldorado plant at Beaverlodge, in Canada, where the minerals are pitchblende and uraninite. Since the uranium is partially in the tetravalent state, it is not readUy leached by sodium carbonate solutions unless in the presence of an oxidant. Potassium permanganate is very efiective for this purpose< but air or oxygen under pressure are preferred on economic grounds. The reaction is essentially as follows ... 

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