The exploration of U(VI) concentration improvement in carbonate medium for alkaline reprocessing process

Abstract

The purpose of this study is to improve the concentration of U(VI) in carbonate solution reasonably, which to improve the application potential of the alkaline reprocessing processes. The dissolution behavior of U3O8 in carbonate peroxide solutions was investigated under different conditions, including pH, carbonate concentration, and solid-liquid ratio. The results showed that the dissolution rate of U3O8 increased with the increase of pH from 8 to 11 in the mixed carbonate solution containing 0.5 mol/L H2O2. The role of carbonate ions in the dissolution of U3O8 was further elucidated by observing the dissolution of UO4·4H2O in carbonate solutions. Furthermore, the concentration of U(VI) in 3 mol/L Na2CO3 solution was successfully increased to 350 g/L under ultrasonic-assisted conditions at 60 °C and a solid-liquid ratio at 1/2 g/mL. Meanwhile, it is suggested that increasing the concentration of carbonate ions can improve the stability of the dissolved solution containing uranyl peroxycarbonate complex.