核纯U_3Si_2粉末中铀的测定

Determination of Uranium in Nuclear Grade U_3Si_2 Powder

试样用HNO_3-HF分解,加入H_2SO_4后加热至H_2SO_4冒烟以除去Si、HNO_3和HF。在含有氨基磺酸的浓磷酸溶液中,用过量FeSO_4将铀(Ⅵ)还原到铀(Ⅳ)。剩余的Fe^(2+)以钼(Ⅵ)作催化剂,用HNO_3氧化。加入VOSO_4溶液后,用标准K_2Cr_2O_7溶液滴定铀(Ⅳ)至铀(Ⅵ),以电位法确定滴定终点。方法的精密度优于±0.1%,误差≤±0.1%。

The sample is dissolved in the HNO_3-HF solution. Si, HNO_3 and HF are eliminated by heating H_2SO_4 to fune after H_2SO_4 is added into the solution. U(Ⅵ)is reduced to U(Ⅳ) with the excess FeSO_4 solution and the remainder Fe^(2+)is oxidized with HNO_3 under the catalysis of Mo(Ⅵ) in the concentrated H_3PO_4 solution containing sulphamie acid. After the VOSO_4 solution is added, U (Ⅳ) is oxidized to U (Ⅵ) by dripping the standard K_2Cr_2O_7 solution. The end-point of titration is indicated with the potential in the solution. The precision is better than 4±0.1%. The error is less than ±0.1%.