Dealing with hazardous waste is a complex undertaking with unexplored potential. Now scientists at the Ural Federal University in Russia have discovered a new way to extract uranium from radioactive sludge.
Much of the today’s radioactive waste is low in uranium content; estimated at below 1%. The researchers targeted this uranium-containing sludge, seeing it as a waste stream in dire need of greater recycling.
‘We managed to extract uranium suitable for return to nuclear fuel production,’ says Ksenia Nalivaiko, lead researcher on the project. ‘Our proposed method allows us to solve several important problems simultaneously when applied on an industrial scale: processing radioactive waste and obtaining valuable uranium as well as associated useful materials.’
At the first stage of research, samples of sludge were subjected to the traditional method of leaching with sulphuric acid while varying the acid concentration, temperature and duration. The researchers found that the most effective leaching from waste occurs when the acid concentration is 200 grams per litre and the solution is maintained at 80C for four hours. In doing so, uranium extraction is maximised at 99.98%.
At the second stage, samples of the uranium-containing sulphuric acid solution were passed through ion-exchange resins of various industrial grades. The resins were then washed with distilled water while the uranium was desorbed from the saturated ion-exchange resin by a solution of sulphuric acid and ammonium nitrate. As a result, the uranium concentration increased up to eight times.
Further neutralisation yields concentrated the uranium precipitate. The uranium content was 68.5% and the isotopic composition of uranium in the precipitate and the content of impurities both meet international quality standards.
The research has been published in the Journal of Environmental Chemical Engineering.
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