Recovery of uranium values from treatment effluents - by precipitation of uranium oxide complexed with ammonia and hydrogen fluoride

摘要

The uranium values are recovered from the effluents produced in the mfr. of UO2 from UF6 by a three stage process. In stage 1 the effluent at pH 9-9.5, contg. NH4F, (NH4)2CO3 and traces of uranium is neutralised to pH 7-7.5 with H2SO4 so that the carbonate ion concn. decreases to 5 g/l. The neutralised soln is treated with NH3 in stage 2 to raise the pH to 8.5-9 and an excess of H2O2 is added which pptes a new uranium cpd. UO4.2NH3.2HF which is yellow and is characterised by a monoclinic crystal structure in which the unit cell parameters a,b and c are 11.719 plus-or-minus 0.002 A. 6.648 + 0.001 A and 4.225 + 0.001 A respectively. The material is readily sepd. by filtration with a sepn factor of 99% and the uranium value converted to UO2. In stage 3 the filtrate from the sepn. of UO4.2NH3.2HF is treated with an excess of lime to approximately pH 12. and an easily filterable ppte. contg. CaF2, CaSO4 and CaOxH2O is produced. H2O and NH3 recycled to stage 2 and to the main UO2 prodn. process. The filtrate following the sepn. of the Ca cpds. and then be discharged without any environmental danger.