Wet Process for Uranium VI Fluoride Manufacture

In the production of uranium(lV) oxide in the wet process, the uranium concentrate is first converted into a uranyl nitrate solution with nitric acid. After the purification of the uranyl nitrate by solvent extraction, it can be converted into uranium(IV) oxide by two different routes either by thermal denitration to uranium(VI) oxide which is then reduced to uranium(IV) oxide or by conversion of uranyl nitrate into ammonium diuranate which is reduced to uranium(IV) oxide. Purification proceeds by extraction of the uranyl nitrate hydrate from the acidic solution with tri-n-butylphosphate in kerosene and stripping this organic phase with water, whereupon uranium goes into the aqueous phase. 

This diluted aqueous uranyl nitrate solution is evaporated to uranyl nitrate hexahydrate, U02(N03)2 6H2O, which is then calcined to uranium(VI) oxide in a fluidized bed furnace  

Conversion of UO2 to UF4 proceeds with anhydrous hydrogen fluoride (dry process) in fluidized bed, screw-reactor or moving bed reactor 

Manufacture of UFs from UF4 -1- F2 in flame-reactors or fluidized bed reactors 

The temperature must not exceed 400°C, to prevent the formation of U3O8. The nitrous gases produced are processed to nitrie aeid, whieh is recycled. The subsequent reduction of uranium(VI) oxide to uranium(IV) oxide with hydrogen at 500°C also proceeds in the fluidized bed furnace. 

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The wet process for uranium(VI) fluoride manufacture is utilized in the Kerr-McGee process, in which the reduction proceeds with a H2/N2-mixture from ammonia cracking and hydrofluorination is carried out in a two stage fluidized bed. British Nuclear Fuel Ltd and Eldorado Nuclear Ltd/Canada also use wet processes. 

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