Patent GB-833622-A (GB)
Title: Processes of reclaiming uranium from solutions
IPC: C22B60/02
Filed: 1945-04-11
Abstract: <PICT:0833622/III/1> In the separation of isotopes of uranium by means of a calutron, such as is described in Specification 816,772, by vaporizing a charge of uranium tetrachloride, in a manner described in more detail below, the uranium containing residues deposited in the source region of the calutron are removed by washing, preferably with hot water, and the uranium dissolved is reduced to its lower valent state and precipitated as hydroxide by the addition of ammonia.  The slurry so formed is subjected to froth-flotation to remove impurities leaving a purified uranous hydroxide slurry. The reduction is preferably effected by the addition of scrap iron.  The calutron is a device for separating isotopes by vaporizing a compound of the element concerned and subjecting the vapour to ionization and thereafter segregating ions from the vapour and accelerating them at high velocity through an electromagnetic field which deflects them along curved paths the radii of curvature of which are proportional to the square root of the masses of the ions.  The ions are thereby concentrated in a collector member of the calutron which consists of two adjacent pockets in a stainless steel block; in the present instance, starting by vaporizing a charge of uranium tetrachloride, the pockets will contain uranium enriched with U235 and U238 respectively.  Such calutrons are preferably employed in series whereby the U235 from the first pocket of the collector of the first cauldron is converted to uranium tetrachloride and subjected to treatment in the second calutron, thereby obtaining a doubly enriched fraction of U235 in the first pocket of the second calutron.  At the same time in both calutrons a considerable amount of uranium tetrachloride charge is condensed on the various parts of the calutron, particularly near the source.  The present invention is applied to such uranium tetrachloride.  As shown in Fig. 2 the source region of the calutron are scrubbed with hot water to dissolve uranium tetrachloride together with copper, iron and carbon impurities. The washings containing dissolved and suspended materials is reduced by agitating with iron scrap and the solution decanted and adjusted to a pH of 4 to 4.8 by means of ammonia to precipitate uranous hydroxide.  The solution is filtered and the precipitate is washed with hydrochloric acid having a pH of 3.5 to 5.  The washed precipitate is re-pulped with water and the slurry is treated in a pneumatic flotation machine employing for example pine, or eucalyptus oil or cresylic acid as flotation agent, whereby the froth carries away the carbon, iron, copper and other impurities leaving finely-divided uranous hydroxide suspended in the slurry.  The slurry is filtered and the uranous hydroxide precipitate may be calcined in nitrogen or hydrogen at about 250 DEG  C. to produce uranium dioxide which may be converted to uranium tetrachloride for re-cycling to the first stage calutron. The conversion of the uranium dioxide to tetrachloride is preferably effected by means of carbon tetrachloride in the vapour phase at about 450 DEG  C. and the uranium tetrachloride so produced may be sublimed at 600 DEG  C. leaving the impurities, uranium dioxide and uranium oxychloride as residues.