Solid solutions uranium-molybdenum

Uranium reacts with most nonmetallic elements to form a variety of compounds, all of which are radioactive. It reacts with hot water and dissolves in acids, but not in alkalis (bases). Uranium is unique in that it can form solid solutions with other metals, such as molybdenum, titanium, zirconium, and niobium. 

Properties Dense, silvery solid. D 19.0, mp 1132C, bp3818C, heat of fusion 4.7 kcal/mole, heat capacity 6.6 cal/mole/C. Strongly electropositive, ductile and malleable, poor conductor of electricity. Forms solid solutions (for nuclear reactors) with molybdenum, niobium, titanium, and zirconium. The metal reacts with nearly all nonmetals. It is attacked by water, acids, and peroxides, but is inert toward alkalies. Green tetravalent uranium and yellow uranyl ion (U()2") are the only species that are stable in solution. 

Impurities in a uranium sample can strongly affect the phase-transition temperatures. Both a and P phases of uranium are complex, and do not form many sohd solutions conversely, the Y phase forms extensive solid solutions. For instance, addition of molybdenum to uranium... 

Thus there is considerable incentive to find extractants that could tolerate higher quantities of solids in H2SO4 leach liquors. Stripping of uranium from the Amex process extractant and subsequent regeneration of the amine solvent also consume considerable quantities of acid and base. Recovery of uranium from H2SO4 solutions would be simplified if a convenient neutral extractant could be found. An extractant with better selectivity for vanadium and molybdenum than HDEHP and long-chain amines is also desirable. 

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