氯化亚锡-次甲基蓝-重铬酸钾无汞滴定法测定铁矿石中全铁

Determination of total iron in iron ore by stannous chloride-methylene blue-potassium dichromate mercury-free titration

以次甲基蓝作为预还原指示剂,建立了氯化亚锡还原,重铬酸钾无汞滴定铁矿石中全铁的分析方法。探讨了方法的基本原理和测定条件,并试验了预还原反应指示剂用量对分析结果的影响。结果表明:以SnCl2为预还原剂,次甲基蓝为预还原指示剂时,滴加2～3滴浓度为2.94g/L的次甲基蓝,预还原终点和滴定终点颜色变化敏锐。干扰试验表明铁矿石中大多数元素均不干扰测定。对两种铁矿石进行分析,测定结果的相对标准偏差(RSD)分别为0.34%和0.16%。利用标准方法进行对照试验,发现在95%的置信度下,两种方法所得到的测定值其精密度无显著性差异,两组数据的平均值之间也无显著性差异。

A method for determining total iron in iron ore by potassium dichromate mercury-free titra- tion was established by using methylene blue as pre-reduction indicator and stannous chloride as reduc- tion agent. The fundamental principle and testing condition of the testing method was discussed and the effect of the dosage of pre-reduction reaction indicator on testing result was tested. The result in- dicated the color change of pre-reduction terminal and titration end point was acute by using SnCl2 as pre-reduction agent, methylene blue as pre-reduction indicator and adding 2-3 drops of 2.94 g/L meth- ylene blue. The interference test indicated most elements in iron ore did not interfere with the test. A- nalysis was conducted on two types of iron ore, with RSD of 0.34% and 0.16% respectively. Control test was conducted by standard method. It was found under the confidence level of 95%, no signifi- cant difference was found on the precision of the test results of both methods. No significant differ- ences were found between the average values of both data as well.