硫代硫酸钠滴定法连续测定铜磁铁矿中铜和铁

Continuous Determination of Copper and Iron in Copper Magnetite by Sodium Thiosulfate Titration

建立硫代硫酸钠滴定法连续测定铜磁铁矿中铜和铁含量的方法。样品经盐酸和硝酸分解,氢氟酸挥硅后,加入乙酸铵、氟化氢铵掩蔽铁离子,调节溶液的p H值在3.0~4.0之间,采用碘量法先滴定铜。在滴定铜后的溶液中,加入过量的三氯化铝溶液,释放被掩蔽的铁离子,用盐酸调节溶液的p H值在1.2~2.2之间,再用碘量法滴定铁。铜含量在0.10%~2.5%之间时,方法的相对标准偏差为2.54%~8.57%(n=11),与YS/T 1047.1法的相对误差小于10.7%,重复性限为r=0.038 3x+0.033 5,再现性限R=0.035 9x+0.056 4。铁含量在38.0%~62.0%之间时,方法的相对标准偏差为0.245%~0.355%(n=11),与YS/T 1047.2法的相对误差小于0.68%,重复性限为r=0.000 75x+0.724 2,再现性限为R=0.004 0x+0.712 6。该方法精密度高,操作简单、快速,分析成本低。

A mothod for determination of copper and iron in copper magnetite by thiosulfate titration was established. The sample was dissolved in hydrochloric acid and nitric acid,silicon was removed by hydrofl uoric acid. After iron ion was masked by ammonium acetate and ammonium hydrogen fl uoride,p H value of the solution was adjusted between 3.0–4.0 and copper was titrated by iodimetry. Excess aluminium chloride was added in tritrated solution to release iron ion. After p H value of the solution was adjusted between 1.2–2.2 by hydrochloric acid,iron was titrated by iodimetry. Compared with YS/T 1047.1,the relative error was less than 10.7%,repeatability limit was r=0.038 3x+0.033 5 and reproducibility was R=0.035 9x+0.056 4,the relative standard deviation of this method was 2.54%–8.57%(n=11) when copper content was 0.10%–2.5%. Compared with YS/T 1047.2,the relative error was less than 0.68%,repeatability limit was r =0.000 75x+0.724 2 and reproducibility limit was R=0.004 0x+0.712 6,the relative standard deviation of this method was 0.245%–0.355%(n=11) when iron content was 38.0%–62.0%. This method has advantages of high precision,simple,fast and lower cost.