以抗坏血酸作还原滴定剂电位滴定法测定铁矿石中全铁

摘要

提出了以抗坏血酸作为还原滴定剂、全自动电位滴定仪判定滴定终点的测定铁矿石中全铁的方法.对滴定酸介质和酸度、温度、电位滴定仪参数进行了优化,对干扰元素的影响等进行了试验.结果表明,全铁可在铁矿石溶样的酸介质及酸度下滴定,无需进行酸度调节,滴定的温度范围为50～80℃.采用过氧化氢或过硫酸铵作预氧化剂,过量的预氧化剂煮沸数分钟即可除去,操作简便.铁矿石中大多数元素均不干扰测定,尤其是铜、钼、钒的允许量可达到5%(质量分数).测定结果相对标准偏差(RSD)小于0.2%.对两个铁矿石标准样品进行加标回收试验,得到加标回收率分别为99.6%和100.4%.%The determination method of total iron in iron ore using ascorbic acid as reducing titrant was development. The end point of titration was determined by full-automatic potential titrimeter. The titration acid medium and acidity, temperature, and potential titrimeter parameters were optimized.The influence of interference elements was tested. The results showed that titration of total iron could be carred out in the medium and acidity of dissolving iron ore samples without pH adjustment. The titration temperature range was 50 -80 ℃ . The hydrogen peroxide or ammonium persulfate was used as pre-oxidant. Since the excessive pre-oxidant could be removed by boiling for a few minutes, the operation was easy. The majority elements in iron ores did not intcrfcrc in the determination, especially the tolerant amount of copper, molybdenum and vanadium could be up to 5 ％ (mass fraction). The relative standard deviation (RSD) of determination results was less than 0. 2 ％ , and the recoveries for two samples were 99. 6％ and 100. 4 ％ ,respectively.