Plant start-up operation of treatment of liquid radioactive waste containing uranium in sulfuric acid by means of ion exchange

The hydrometallurgy of uranium developed by CCHEN in the '80s generated different types of liquid radioactive waste: organic and aqueous, which have to be treated to extract the uranium, obtaining uranium concentrate less than 3 [ppm], in order to comply with the current regulations and to be able to be discharged as industrial waste over to specialized companies. The radioactive wastes were treated using strongly basic ion exchange resins to obtain a lower volume of concentrated uranium in solid phase. Batch processes were carried out with different pH values (1.4-1.6-1.7-1-8 and 2.0) and different residence times (5-10-15-240 [min]), to define the optimum processing conditions. Three resins were used: IONAC, AFP-329, IONAC A-641, DOWEX 11. The load capacities for each one were: 2[g/l], 1.85 [g/l] and 2.1 [g/l], respectively. Dowex 11 obtained the best uranium load results. Because of the nature of the treated solutions, the pH variation with sodium hydroxide generated precipitation and then crystallization of the existing pieces. Ninety-five percent of the resin's maximum load was attained after about 20 [min] of residence time. Continuous tests were carried out at the solution's original pH to verify the results obtained in the batch stage. This ion exchange process was compared with the chemical precipitation, with lime and sodium hydroxide as well as evaporation and in both processes the volumes of solid that were generated were significantly greater. The ion exchange plant worked with two serially connected columns, using 10 [l] of Dowex 11 resin in each one, with a residence time of 20 [min] per column. A total of 8 [m3] of solution, obtaining an effluent with a uranium concentrate of less than 3 [ppm], using 140 [l] of resin, which generated an average load of 3 [g/l] of uranium (au)