Sodium uranyl vanadate

From 600°C to 8S0°C sodium vanadates are formed, and these then react with uranium compounds to form sodium uranyl vanadates which are readily soluble. 

Above 8S0°C sodium vanadates and sodium uranyl vanadates decompose, or react with silica to produce insoluble silicates. 

For the treatment of camotite several methods are available. The method recommended by the United States Bureau of Mines2 is as follows The ore is leached with concentrated nitric acid at 100° C., neutralised with caustic soda, and barium chloride and sulphuric acid added to the solution to precipitate the radium as barium-radium sulphate. The precipitate settles in three or four days, after which time the clear liquid is decanted into tanks and is treated with excess of boiling sodium carbonate solution in order to precipitate any iron, aluminium and chromium present. The solution now contains sodium uranyl carbonate and sodium vanadate. It is nearly neutralised with nitric acid, and caustic soda is added in sufficient quantity to precipitate the uranium as sodium uranate. After filtering, the remaining solution is neutralised with nitric acid and ferrous sulphate added, whereupon iron vanadate is thrown down. By this method it is claimed that 90 per cent, of the radium, all the uranium, and 50 per cent, of the vanadium in the camotite are recovered. 

Uranyl-vanadates.—By adding uranic anhydride to fused potassium or sodium metavanadate, microscopic, rectangular, fluorescent plates of the compositions K(U02)V04 and Na(U02)V04 are obtained. These are probably derivatives of a relatively stable uranyl-... 

Camotite is a potassium uranyl vanadate, K2O.2UO3.V2O5.11H2O. Since the uranium is in the fully oxidized condition, leaching can usually be carried out without an oxidant, at a particle size of about 100 mesh. The vanadium dissolves on leaching, to sodium vanadate, and the uranium forms a soluble double carbonate. The reaction may be represented approximately as ... 

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