粉类磁性金属物测定方法的研究

DETERMINATION OF MAGNETIC POWDERY METALS IN GRAIN

将通过磁性金属测定仪收集到的磁性金属物与残余试样的混合物,分别采用分离板分离法和四氯化碳漂洗法进行比较试验。试验结果证明:采用分离板分离法的回收率平均值为99.01%,标准差为1.99;四氯化碳漂洗法的回收率平均值为99.42%,标准差为11.38;二者的回收率平均值差为0.41%,按国家标准限量为0.003g/kg计算,0.41%的差值相当于0.00001g/kg,对测定结果没有影响。分离板分离法具备回收率高、结果准确可靠,操作方法简单、快速,降低检验成本和劳动强度等优点,又避免了四氯化碳对人体的毒害和因废弃物处理不当污染环境等缺点。为此,在方法中用分离板分离法替代了四氯化碳漂洗法;同时建议取消了检出率偏低,回收率平均值仅为49%的马蹄形磁铁检出法。

A mixture of magnetic metals and residual samples was collected by magnetic metal tester, and comparing tests were conducted by isolation method with separating plates and carbon tetrachloride fulling respectively. The results showed that the average recovery rate was 99. 01% and the standard deviation was 1.99 by isolation method with separating plates, the average recovery rate was 99.42 % and the standard deviation was 11.38 by carbon tetrachloride fulling, and the mean difference of recovery rate between them was 0. 41%, equalizing 0. 00001 g/kg. However, according to 0. 003 g/kg of the national standard limit, it had no influence on the real value. There were many advantages for isolation method with separating plates, such as high recovery rate, precise value, easy and rapid operation, low cost and labor intensity etc., and avoiding body from carbon tetrachloride poison and preventing environmental pollution. So carbon tetraehloride fulling was replaced with isolation method with separating plates in this experiment. It also suggested that detection method with horseshoe magnet could be abolished, which the average recovery rate was only 49 %.