高温水解-离子色谱法测定有色金属矿中氟和氯

采用自动化高温水解装置处理样品,建立了高温水解离子色谱法测定有色金属矿中氟和氯含量的方法。对比了水蒸气蒸馏法和高温水解法的样品前处理效果,确定了高温水解法为样品前处理方法。考察了高温水解过程催化剂的使用情况,并采用高温灼烧的方法驱除了催化剂中的氟和氯,消除其对测定结果的影响。实验方法在测定范围内氟和氯的含量与峰面积呈良好的线性关系,相关系数R²均为0.9999;方法检出限为0.11ng/mL(氟)和0.24ng/mL(氯)。按照实验方法对有氟含量认定值的铜精矿及没有氟和氯认定值的多金属矿有证标准物质进行测定,统计测定结果的相对标准偏差(RSD)均小于5%(n=11);铜精矿中氟的测定值与认定值一致,多金属矿中氟和氯的加标回收率为97.0%~100.0%。对来自不同国家的铅精矿、铜精矿和锌精矿进行检测,氟、氯的测定结果分别与离子选择电极法和电位滴定法的测定结果基本一致。实验方法与离子选择电极法相比,检出限由g/mL降低至ng/mL;采用的高温水解法与现有的水蒸气蒸馏法相比,待测组分提取率更高,解决了水蒸气蒸馏法不能有效提取硫含量较高的铜精矿、铅精矿和锌精矿等样品中氟和氯的问题。

Determination of fluoride and chloride in nonferrous metal oreby pyrohydrolysis-ion chromatography

The sample was treated in automatic pyrohydrolysis device. The determination method of fluoride and chloride contents in nonferrous metal ore by pyrohydrolysis-ion chromatography was established. The pretreatment effect of sample by steam distillation and pyrohydrolysis was compared. The sample pretreatment method of pyrohydrolysis was selected in this study. The use condition of catalyst in pyrohydrolysis process was investigated. The fluoride and chloride in catalyst was removed by pyrohydrolysis to eliminate their influence on determination results. The content of fluoride and chloride in determination range had good linear relationship to the peak area. The correlation coefficients were both 0.9999. The detection limit of fluoride and chloride in this method was 0.11ng/mL and 0.24ng/mL, respectively. The copper concentrate with certified value of fluoride as well as certified reference materials of polymetallic ore without certified values of fluoride and chloride were determined according to the experimental method. The relative standard deviations (RSD, n=11) were all less than 5%. The found result of fluoride in copper concentrate was consistent with the certified value. The spiked recoveries of fluoride and chloride in polymetallic ore were between 97.0% and 100.0%. The lead concentrate, copper concentrate and zinc concentrate samples from different countries were determined, and the found results of fluoride and chloride were basically consistent with those obtained by ion selective electrode method and potentiometric titration method, respectively. The experimental method was compared with the ion selective electrode method, and the detection limit was reduced from g/mLto ng/mL. Compared to the existing steam distillation method, the pyrohydrolysis process improved the extraction rate of testing components. It solved the problem that the fluoride and chloride in copper concentrate, lead concentrate and zinc concentrate samples with high sulfur content could not be extracted by steam distillation method.