重铬酸钾滴定法快速测定钛铁矿中钛铁含量

Rapid determination of titanium and iron in ilmenite by potassium dichromate titrimetry

利用磷酸脱水后的缩合物具有较强的酸性和配位性,试样经磷酸在高温下加热5min溶解后,在酸性条件下,被铝片,氯化亚锡还原,然后以中性红和二苯胺磺酸钠作指示剂,采用重铬酸钾滴定法分别测定了钛铁矿中钛、铁含量。研究了溶样条件、样品细度、溶解时间和还原酸度对测定的影响,确定了最佳实验条件。采用本方法对实际样品中钛、铁进行测定,测定值与经典的硫酸高铁铵-汞盐法测得结果一致,相对标准偏差(n=5)均小于0.2%和0.5%。采用本方法对钛铁矿标准样品(YSBC19704-76)中钛、铁进行5次测定,测定结果与认定值相符,相对标准偏差分别为0.12%和0.62%,。

The condensation compound after phosphoric acid dehydration had strong acidity and coordi- nation properties. After the samples were dissolved in phosphoric acid by heating at high temperature for 5 min, the titanium and iron was reduced by aluminum sheet and stannous chloride under acid con- ditions. Then, the content of titanium and iron in ilmenite was respectively determined by potassium dichromate standard solution with neutral red and sodium diphenylamine sulfonate as indicator. The effect of sample dissolution condition, sample size, dissolution time and reducing acidity on determina- tion was investigated to obtain the optimal experimental conditions. The determination results of tita- nium and iron in actual sample by this method were consistent with those obtained by classical ammo- nium ferric sulfate-mercury salt method, and relative standard deviations （n=5） was smaller than 0.2 and 0.5 %. This method has been applied into the determination of titanium and iron in ilmenite certified reference materials YSBC19704-76 for five times. The results were consistent with the certi- fied values, and relative standard deviations were 0.12 % and 0.62 %, respectively.