Recovery of uranium from conversion production sludge by leaching with nitric acid and subsequent ion-exchange concentration

Physicochemical studies of the sludge of uranium conversion production were carried out to determine the possibility of its processing and return of uranium to the nuclear fuel cycle. It has been established that the sludge was mainly represented by calcium compounds: CaSO₄·2H₂O (60.1 wt%), CaCO₃ (25.1 wt%), CaF₂ (13.7 wt%), and silicon dioxide (1.2 wt%). The content of uranium in the sludge was 0.15 wt%. It was shown that it was possible to achieve high degrees of uranium extraction from the sludge using nitric acid as a leaching agent. The use of phosphorus-containing ion-exchanger Tulsion CH93 ensured the effective concentration of uranium from highly acidic pregnant leach solutions. The full dynamic exchange capacity achieved 15.7 kg m⁻³. The degree of uranium desorption by ACBM (ammonium carbonate/bicarbonate mixture) solutions was 83%. The final product was ammonium uranyl phosphate hydrate NH₄UO₂PO₄∙3H₂O with a uranium content of 52.5 wt%.