氢还原重量法测定铼酸铵制备铼粉产品中铼

通过先测定铼粉产品中杂质元素总含量,再用差减法计算铼含量的方法较为繁琐。根据低温氢还原时,除了铼氧化物Re_2O_7、ReO_2,共存金属杂质元素和他们的氧化物均被还原为金属单质而不挥发外,其余非金属元素和他们的氧化物,以及水分、铵盐均会被挥发除去这一基本原理,实验提出了采用低温氢还原样品,以氢还原前后样品质量之比计算铼的含量,最终实现了氢还原重量法测定铼酸铵制备铼粉中铼的方法。确定的实验条件如下:样品量约1.0g;采用分段升温方式进行氢还原,其程序为先室温升温至200℃,恒温30min后升温至400℃,接着恒温30min后升温至600℃,最后再恒温30min;将盛有氢还原后铼粉的石英舟置于干燥器中冷却30min,恒重1次。实验方法适用于铼粉中不挥发杂质元素总质量分数不大于0.010%时铼的测定。将实验方法用于3个铼粉管理样品、4个铼粉实际样品中99.824%~99.995%铼的测定,测定值与参考值基本一致,相对标准偏差(n=9~22)为0.001 2%~0.003 3%,加标回收率99.99%~100.01%。

Determination of rhenium in rhenium powder products prepared with ammonium rhenate by hydrogen reduction gravimetry

The total content of impurity elements in rhenium powder products is measured. Then the content of rhenium can be obtained by subtraction method. However, this method was complicated. During low temperature hydrogen reduction, besides of rhenium oxides (Re₂O₇ and ReO₂), the coexisting metal impurities and their oxides will be also reduced to non-volatile metal elements, while nonmetal elements and their oxides as well as water and ammonium salt will be volatilized and removed. Based on this principle, the sample was treated by low temperature hydrogen reduction. The percentage of rhenium was calculated according to the mass ratio of sample before and after reduction. The determination method of rhenium in rhenium powder prepared with ammonium rhenate by hydrogen reduction gravimetry was established. The following experimental conditions were obtained: the sample mass was about 1.0 g; the hydrogen reduction was conducted in temperature-gradient mode (increased from room temperature to 200 ℃ and kept for 30 min, then increased to 400 ℃ and kept for 30 min, finally increased to 600 ℃ and kept for 30 min); the quartz boat containing rhenium powder after hydrogen reduction was cooled in dryer for 30 min (constant weight for one time). The experimental method was applicable for the determination of rhenium in rhenium powder (total mass fraction of non-volatile impurities was not more than 0.010%). The content of rhenium (99.824%-99.995%) in three management samples and four actual samples of rhenium powder was determined. The found results were consistent with the reference values. The relative standard deviations (RSD, n=9-22) were between 0.0012% and 0.003 3%, and the recoveries were between 99.99% and 100.01%.