无汞法测定铁矿石中铁含量实验的改进

Improvement of Determination of Total Iron Content in Iron Ore by None-mercury Method

对经典的无汞定铁法进行改进。采用硫-磷混酸溶解铁矿石,在一定温度下用氯化亚锡充分还原Fe(Ⅲ),迅速滴加甲基橙指示并除去过量氯化亚锡,还原得到的亚铁立即用重铬酸钾标准溶液滴定,稍过量的甲基橙不影响测定结果。实验得出溶解铁矿石的最佳温度为160℃,硫-磷混酸的最佳比例为3∶2,最佳用量为15 m L,最佳还原温度为70℃。改进后的实验方法操作更简便,现象更明显,同时成本降低,准确度高,精密度好,且消除了用盐酸溶解矿样时存在的酸液挥发污染环境的问题。

The determination of total iron content in iron ore by none-mercury method was improved. Sulfur-phosphorus mixed acid was used to dissolve the iron ore and enough stannous chloride was added to reduce Fe( Ⅲ) at certain temperature. Methyl orange,which was dropt as an indicator to remove the excess of stannous chloride,was put into the solution drop instantly. The amount of Fe( Ⅱ) obtained in the system was titrated by potassium dichromate standard solution immediately. The optimum experimental conditions were as follows: the optimum temperature of dissolved iron ore was 160 ℃,the optimum reduction temperature was 70 ℃,the optimum ratio of sulfur-phosphorus mixed acid was 3∶2 and the optimum dosage was 15 m L. There were some advantages about the improved experiment such as easier operation,obvious phenomenon,lower cost,higher accuracy and precision. What's more,there will be no problem of affecting the environment by acid evaporation.