分光光度法测定铁矿石中钍含量

Determination of Thorium Content in Iron Ore with Spectrophotometry

采用盐酸、氢氟酸分解铁矿石试样,高氯酸冒烟飞硅后,再经过1-苯基-3-甲基-4-苯甲酞墓咄哇酮-5(PMBP)的乙酸丁酯溶液萃取,盐酸反萃取消除钍的干扰元素,利用偶氮胂Ⅲ为显色剂,与钍离子形成紫红色螯合物,通过分光光度计测定铁矿石中钍的含量。文章探讨了萃取及反萃取反应的酸度选择、显色反应的酸度、显色剂用量、显色时间等因素对测定的影响,并优化了试验参数。在最大吸收波长660 nm处,确定了钍的线性范围为0~1.0μg/mL,相关系数不低于0.999,检出限为0.00044μg/mL。该方法操作简便,偶氮胂Ⅲ与钍形成的络合物的摩尔吸光系数高达0.8×10^(5)L/(mol·cm),具有较高的灵敏度,样品中钍分析结果的加标回收率在96.8%~105.8%,方法具有良好的精密度和准确度。

The iron ore samples are decomposed with the hydrochloric acid and hydrofluoric acid.After the perchloric acid smokes and silicon is eliminated,it is then extracted by butyl acetate solution of 1-phenyl-3-methyl-4-benzophthalide-5(PMBP).The interference elements of thorium are eliminated by the reextraction with hydrochloric acid,arsenazo Ⅲ is as color developing agent and forms purple-red chelate with thorium ion as well as the thorium content in iron ore is determined with spectrophotometer.In the paper,the selection of acidity for extraction and reextraction,effects of such factors as acidity of chromogenic reaction,amount of color developing agent and color developing time on determination are discussed as well as experimental parameters are optimized.At the maximum absorption wavelength of 660 nm,the linearity range of thorium is determined to be 0~1.0μg/mL,correlation coefficient is not less than 0.999 and detection limit is 0.00044μg/mL.This method is easy and simple to operate,molar absorption coefficient of the complex formed by arsenazo Ⅲ and thorium is up to 0.8×10^(5)L/(mol·cm),which is with higher sensitivity.The adding standard recovery of thorium in the analysis results of samples is 96.8%~105.8%,so the method is with good precision and accuracy.