Method and apparatus for continuous conversion of uranium hexafluoride in ammonium diuranate

摘要

Process and apparatus for producing ammonium diuranate (ADU) from uranium hexafluoride (UF.sub.6) wherein gaseous UF.sub.6 is first hydrolyzed, then partially neutralized with aqueous ammonium hydroxide to a pH of from 5 to 6, the resultant solution is conveyed to a precipitation vessel wherein it is admixed with additional aqueous ammonium hydroxide to a pH of from 9.8 to 10.2 whereby ADU solids precipitate, the resultant suspension is substantially continually withdrawn from the precipitation vessel and a stream of the suspension is forcefully injected back into the side of the vessel at the liquid surface at an angle to the horizontal liquid surface in the precipitation vessel to cause intense agitation and circulation or tumbling of the suspension in said vessel, the volume of the suspension being so withdrawn and circulated constituting a turnover of the total suspension volume in the vessel in the order of about a minute or less, whereby fine ADU crystals with closely consistent properties are produced, so that digestion tanks and storage vessels previously necessary in the ADU process are eliminated. A small portion of the slurry suspension from the precipitation vessel in continually withdrawn and centrifuged to provide an ADU solids stream of consistently and controllably uniform properties such that when fed to a calcining kiln it produces UO.sub.2 powder of highly uniform characteristics rendering it suitable for producing UO.sub. 2 fuel pellets of about 95% of theoretical density, without milling the UO.sub.2 to a finer particle size.