Determination of Micro-amount of Uranium in Ore by Microtitration with Reduction of Ammonium Vanadate by Titanous Chloride

Based on the titrimetry with reduction of ammonium vanadate by titanous chloride for the determination of micro-amount of uranium, some operation procedures in sample digestion, filtration and washing, reduction-oxidation and titration were improved. Samples were digested with H₃PO₄-HCl-H₂O₂ at low temperature. After centrifugation, filtering, reduction of UO²⁺₂ with Ti³⁺, oxidization of excessive Ti³⁺ by NaBrO₃ and further oxidization of trace impurities with low valence by urea-NaNO₃, uranium in the sample solution in a small volume (10 mL) was titrated with ammonium vanadate. The end point of the titration was very clear. Detection limit of the method for uranium was 0.001% and precision was 0.05%~ 0.07%RSD. The method provides the advantages of simple operation, high efficiency and is suitable for the determination of 0.001%~0.01% uranium in ore and slag samples.