Curium distilled metal

Starting from prepurified oxides and using lanthanum metal as reductant, volatile Am, Cf or Es have been isolated and purified by repeated distillation or sublimation. Thorium was used successfully as reductant for actinium and curium oxides (2) ... 

Curium has also been made on a gram scale by extraction from a melt of MgCl2, MgF2 and Cm02 with molten Zn—Mg alloy, the excess of which is then distilled off 4 uranium can also be obtained as an amalgam, from which it can be recovered, by action of Na/Hg on uranyl acetate.5 The melting points of the metals are given in Table 28-1. 

Americium and curium can be obtained from the aqueous waste of the Purex process. This americium is a mixture of Am and " Am. Isotopically pure Am, the decay product of " Pu, can be obtained from aged plutonium. Solvent extraction and ion-exchange procedures are used to recover americium from waste streams. Americium metal is produced by lanthanum reduction of the oxide, followed by vacuum distillation of the americium at 1400°C. 

Curium metal has an entropy of vaporization remarkably similar to that of gadolinium, although its vapor pressure is about double that of gadolinium over the measured range [33]. The metal vapor pressure of triply distilled Cm metal has been measured between 1300 and 2000 K and obeys the following relations [33] ... 

A fused salt-molten metal process has also been examined for separating californium [36, 37]. In principle, it may also be possible to reduce actinide oxides with thorium metal and distill away the more volatile californium metal (see Section 11.6.1). The separation of californium oxide from curium oxide using a vacuum sublimation procedure has also been reported [38]. 

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