Morphology and crystal structure characterization on UO₂ powder from yellow cake with variation precipitation ADU temperature

The conversion process of uranium on yellow cake from phospate fertilizer waste has been done by dissolve it with HNO₃. The purification done by extraction to result uranyl nitrate hydrate (UNH). UNH was settling into ammonium diuranate (ADU) with three variations temperature at 65, 70 and 75°C. ADU was calcined into triuranium octoxide (U₃O₈) through uranium trioxide (UO₃) and it reduced to UO₂ powder. O/U ratio calculation of uranium, crystal structure analysis from XRD diffraction pattern and morphology observation by SEM had been done. The expected result is obtained the optimum temperature to produced sinterable UO₂ powder accordance to ASTM C753-99. The result of O/U ratio for uranium oxide powder is ±2 with fraction of the phase UO₂ for uranium oxide powder is 95 wt%, it structure crystal is cubic with space group F m -3 m and the lattice parameter for UO₂ is 5.467 Å. Morphology of the UO₂ powders formed with fine grain with size around 500 nm to 1000 nm, and tend to agglomeration. According the result, precipitated ADU temperature at 70°C shows an optimum temperature to obtained the sinterable UO₂ powder. (author)