电感耦合等离子体质谱法测定铀铌铅矿重选流程样品中铀

采用HCl、HNO_3、HF和HClO_4溶解铀铌铅矿,以电感耦合等离子体质谱法(ICPMS)测定了铀铌铅矿重选流程样品(原矿、精矿、中矿和尾矿)中铀(U)。通过选择合适的同位素238 U避免了质谱干扰,通过稀释基体质量浓度不大于0.30mg/mL和选择45ng/mL185 Re为内标相结合的方法消除了非质谱干扰。实验表明,在选定的实验条件下,U质谱强度与ρ(U)在5~60ng/mL范围内呈良好的线性关系,校准曲线相关系数r为0.999 2,方法检出限为0.000 4ng/mL。将实验方法应用于铀铌铅矿重选流程中的原矿、精矿、中矿和尾矿实际样品中U的测定,所得结果的相对标准偏差(RSD,n=6)为0.80%~3.9%,加标回收率为102%~106%。采用实验方法对铀铌铅矿重选流程样品(原矿、精矿、中矿和尾矿)中任意3个流程样品中的U含量进行测定,将其测定值代入质量守恒定律计算得到第4个流程样品中U含量的计算值,由实验方法对第4个流程样品中U含量的测定值与其计算值相比可计算得到第4个流程样品中U的回算率,实验表明,U的回算率为98%~106%。

Determination of uranium in gravity concentration process sample of uranium-niobium-lead ore by inductively coupled plasma mass spectrometry

The determination method of uranium in gravity concentration process samples of uranium-niobium-lead ore (raw ore, concentrate, middling and tailing) by inductively coupled plasma mass spectrometry(ICP-MS) was established after dissolving the samples with HCl, HNO₃, HF and HClO₄. The mass spectrometry interference was eliminated by selecting proper isotope (²³⁸U). The non-mass spectrometry interference was eliminated by diluting the matrix (the mass concentration was below 0.30 mg/mL) and using 45 ng/mL ¹⁸⁵Re as internal standard. The experimental results indicated that the mass spectrometry intensity of uranium showed good linear relationship with mass concentration in range of 5-60 ng/mL under the selected testing conditions. The correlation coefficient of calibration curve was r=0.999 2. The detection limit of method was 0.000 4 ng/mL. The proposed method was applied to the determination of uranium in actual gravity concentration process samples of uranium-niobium-lead ore (raw ore, concentrate, middling and tailing). The relative standard deviations (RSD, n=6) were between 0.80% and 3.9%, and the recoveries were between 102% and 106%. The content of uranium in three process samples of uranium-niobium-lead ore (raw ore, concentrate, middling and tailing) was determined according to the experimental method. The determination result was substituted into the law of conservation of mass to calculate the uranium content in the fourth sample. The determination result was compared with the calculation result to obtain the back-calculation rate of uranium content in the fourth sample. The results showed that the back-calculation rates were between 98% and 106%.