|Properties||naturally ocurring mineral [KIR83]|
|Melting point, C|
|Boiling point, C|
|Uranium (uranyl) carbonate, UO2(CO3), is a carbonate of uranium that forms the backbone of several uranyl mineral species such as Andersonite, McKelveyite and Wyartite and most importantly Rutherfordine. It is also found in both the mineral and organic fractions of coal and its fly ash and is the main component of uranium in mine tailing seepage water. Uranium, like other actinides, readily forms a dioxide uranyl core (UO2). In the environment, this uranyl core readily complexes with carbonate to form charged complexes. Although uranium forms insoluble solids or adsorbs to mineral surfaces at alkaline pH, it is these soluble carbonate complexes that increase its solubility, availability, and mobility with low affinities to soil. Uranium(VI) generally forms a pH-dependent suite of uranyl-carbonate complexes in ground water solutions:
A common method for concentrating uranium from a solution uses solutions of uranyl carbonates which are passed through a resin bed where the complex ions are transferred to the resin by ion exchange with a negative ion-like chloride. After buildup of the uranium complex on the resin, the uranium is eluted with a salt solution and the uranium is precipitated in another process.
The uranyl carbonate minerals
Uranyl-carbonate complexes form a large class of mineral species. Several have been described in literature. These include: