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    电位滴定法测定铝土矿中铝、铁、钛含量

    Potentiotitrimetric Determination of Aluminum, Iron and Titanium in Bauxite

    • 摘要: 用氢氧化钠与过氧化钠作为混合熔剂,在镍坩埚中于720 ℃熔融铝土矿样品,再用水和盐酸溶液提取,所得溶液中所含铝、铁、钛3种金属元素的合量以返滴定法用乙二胺四乙酸二钠(EDTA)标准溶液作为滴定剂通过络合反应测定;再以重铬酸钾标准溶液为滴定剂,通过氧化还原反应分别测定铁和钛的含量;从而计算出铝的含量。铝、铁、钛3种元素的检出限分别为1.00%,0.50%,0.50%。三氧化二铝、三氧化二铁、二氧化钛测定值的相对标准偏差(n=10)依次为0.25%~0.32%,0.69%~4.0%,1.1%~2.2%;相对偏差依次为0.24%~0.35%,0.62%~3.41%,0.89%~1.81%。方法减少了样品因人为判定终点所带来的误差,分析程序得以简化的同时提高了工作效率。

       

      Abstract: The fusion of bauxite sample was prepared in nickel crucibles at 720℃ with sodium hydroxide and sodium peroxide as mixed flux, and extracted with water-HCl (by volume ratio of 1 to 1). The total content of aluminum, iron and titanium in the above solution obtained was determined by back potentiometric titration using EDTA standard solution as titrant based on the complexation reaction. Then the contents of iron and titanium were determined by potentiometric titration using potassium bichromate standard solution as titrant based on the redox reaction. Based on the above results, the content of aluminum was figured out. Values of detection limit were found 1.00%, 0.50%, 0.50%. Values of RSDs (n=10) of determination for Al2O3, Fe2O3 and TiO2 were kept in ranges of 0.25%-0.32%, 0.69%-4.0%, 1.1%-2.2%, and relative deviation were kept in ranges of 0.24%-0.35%, 0.62%-3.41%, 0.89%-1.81%, respectively. The error caused by artificial endpoint determination in the proposed method was reduced, and the analysis procedure was simplified and the working efficiency was improved.

       

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