Ammonium diuranate filtrate

Cellulose acetate membrane, HMIL Ammonium diuranate filtrate effluents (ADUF) n/a n/a Prahhakar et al. (1996)... 

Carnotite may be fused Avith potassium hydrogen sulphate and the residue extracted with Avater. From the solution the double sulphates of potassium AAuth uranium and vanadium may be obtained by crystallisation. These are reduced by means of zinc and sulphuric acid, and the vanadium precipitated from the solution by means of ammonia and ammonium carbonate. Ammonium diuranate separates from the filtrate on boiling. ... 

The precipitate is largely freed of fluoride ions after filtration by extraction or recrystallization. After drying at 200°C, the ammonium diuranate is reductively decomposed by a H2/H2O mixture at ca 500°C to UyOg, which is then reduced with hydrogen at 500 to 800°C to uranium(IV) oxide. The reductive decomposition to U Og and its reduction can be carried out in a single step e.g. in a rotary kiln. Since the uranium(IV) oxide formed can be pyrophoric, it is weakly reoxidized. 

After filtration, in the second stage, ammonia is added to bring the pH to 7.0, which precipitates the uranium as ammonium diuranate. The precipitate is filtered, washed with water, and dried at 160°C. Filtrate is added to eluant makeup, to conserve nitrate. 

The diuranate precipitate is separated from the mixed NaG and Na SO4 salt solution by a system of thickeners and filters. Filter cake from the first filter is washed with water, reslurtied with water, filtered a second time, and washed again to reduce its content of NaG and Na2S04. When it is necessary to reduce the amount of sodium diuranate, a third stage of filtration is used, and the filter cake is reslurried with ammonium sulfate instead of water to replace most of the sodium with ammonium ion. Washed filter cake is dried by heating to 160 to 180°C. 

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