三氯化铁—重铬酸钾滴定法测定直接还原铁中金属铁

Determination of Metallic Iron in Direct Reduced Iron by Ferric Chloride-Potassium Dichromate Titrimetric Method

研究了用三氯化铁溶解重铬酸钾滴定法测定直接还原铁中金属铁的方法,试样用三氯化铁溶液选择性的使金属铁溶解,金属铁被氧化为二氯化铁,过滤分离不溶物,定容、移取部分滤液,以硫磷混酸酸化后,二苯胺磺酸钠为指示剂,用重铬酸钾标准溶液滴定金属铁的含量.通过试验,总结出用三氯化铁溶解浸取MFe时三氯化铁溶液的浓度和用量及振荡时间的最佳试验条件.方法操作简便、快速准确,用于直接还原铁中金属铁日常检测,相对标准偏差小于0.134%.

In the paper, the method to determine the metallic iron in direct reduced iron by dissolving po- tassium dichromate titrimetric with ferric chloride was studied. The metallic iron in sample was selectively dissolved by ferric chloride solution, the metallic iron was oxidized to ferrous chloride, then through filte- ring to separate the insoluble matters, and after fixing to a constant volume, a part of solution was re- moved and acidized by mixture of sulfui＇ic phosphoric acid, the content of metallic iron was determined by potassium dichromate standard solution, taking sodium diphenylamine sulfonate as an indicator. By the tests, the optimism test conditions including the density, amount and oscillating time of ferric chloride when MFe was leached by ferric chloride were summarized. This method is simple, rapid and accurate, and its relative standard deviation is less than 0. 134%, when the method was used to the daily inspection of metallic iron in direct reduced iron.