Uranium minerals uranyl molybdates

The frequent occurrence of vanadium in uranium minerals renders the separation of these two metals of importance. One method in use is based on the solubility of uranyl nitrate in ether, %vhilst vanadic and also molybdic and tungstic acids are insoluble. A solution containing these substances may therefore be evaporated to drjmess, and the uranyl salt extracted from the residue with ether. Another method depends upon the fact that uranyl nitrate is readily soluble, whilst vanadium compounds are insoluble, in acetic acid of 95 per cent, strength to which nitric acid has been added in the proportion 1 20. ... 

The order of presentation of the uranium minerals will follow chemical groups. The U minerals are discussed first, followed by the niobates, tantalates and titanates. These two groups include the primary reduced minerals. The uranyl minerals are considered in the order hydrated oxides, silicates, phosphates and arsenates, vanadates, molybdates, sulphates, carbonates, and selenates and tellurates. Each section includes an evaluation of the known crystal chemistry and its effect on chemical variability and occurrence of mineral species. 

The uranyl molybdate minerals are relatively poorly characterized. The first uranyl molybdate mineral was recognized by Brophy and Kerr, but since then a number of minerals that belong to this group have been described from many different deposits (Table 14). An affinity of uranium and molybdenum, especially in roll-front type deposits, has been known for some time. Initially, only minerals with U were recognized, but the occurrence of such minerals as sedovite shows that U compounds also exist. 

Uranium Molybdates.—Uranyl nioh bdate, UO2M0O4, is obtained as a white amorphous precipitate when ammonium molybdate is added to uranyl nitrate solution in the dark. It is reduced to uranous molybdate. U(Mo04)2, becoming green by the action of ethyl or methyl alcohol or acetic acid, and dissolves in mineral acids with a yellovush-... 

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See also in sourсe #XX -- [ ]

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