Carnotite uranium content

A secondary source of supply lies in the carnotite deposits of Colorado and Utah. The vanadium content in these is very low, being only about 1 per cent, or even less, and the ore is really worked for its radium and uranium content, the vanadium forming a by-product. The deposits of carnotite are considerable. 

Dominant ore minerals in the reduced zone are pitchblende and coffinite and, in some deposits, associated primary vanadium oxides—for example, montroseite. In oxidized zones the important uranium minerals are the uranyl vanadates (carnotite, tyuyamunite or francevillite). Accessory elements include Mo, Se and Cu. Average uranium content ranges from 0.01 to 0.40 7o U3O8. 

It has recently been discovered that the roasting of carnotite ore at 850°C in the presence of a few per cent of calcium sulphate, prior to carbonate leaching, enhances both the vanadium and uranium extraction efficiencies. A convenient way of achieving the desired conditions is to blend the ore with another carnotite ore with a high natural calcium sulphate content, when available, rather than waste the beneficial effect of the latter by treating it alone. 

Vanadium is widespread in the earth s crust, twice as abundant as copper and ten times more than lead. Titanium minerals such as ihnenite often have a V-content of 0.1-0.3%. Vanadium is usually obtained as by-product from the extraction of iron from V-containing iron ores, uranium from V-containing carnotite and phosphorus from V-containing phosphate rocks. 

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