T he uranium ore sample is dissolve with H2SO4, HF and H2O2. Uranium (VI) is reduced to uranium (IV) by titanous. The excess titanous is oxidized with sodium nitrite and excess sodium nitrite is destroyed with urea. Uranium can be determined by ammonium vanadate volumetry in the medium of 6 mol/L sulfuric acid taking o-phenanthroline ferrous sulfate as indicators. The determination limit is 0.03%, the RSD is better than 3%, the recovery is 95 similar to 105%. The error is le...