石墨炉消解–EDTA滴定法测定铅矿石及铅精矿中的铅

Determination of lead in lead ores and lead concentrates by graphite furnace digestion–EDTA complex metric titration

建立石墨炉消解-EDTA滴定法测定铅矿石及铅精矿中铅。样品经硝酸-硫酸混酸分解生成硫酸铅沉淀,经过滤与其它元素分离,硫酸铅经乙酸-乙酸铵缓冲溶液溶解,以二甲酚橙为指示剂,用EDTA标准溶液进行滴定,利用消耗EDTA标准溶液的体积来计算样品中铅的含量。样品中铅的检出限为2%。采用该方法对3个铅矿石及4个铅精矿实际样品进行测定,测定结果的相对标准偏差分别为0.32%~0.71%,0.18%~0.30%(n=8),加标回收率分别为97%~101%,97%~103%;对国家标准物质进行测定,测定值与标准值基本一致,相对误差不大于0.052%。该方法操作简单、快速,准确度高,精密度好,可满足铅矿石和铅精矿样品快速检测的需求。

A method for determining lead in lead ores and concentrates by graphite furnace digestion-EDTA complex metric titration was established.The samples were decomposed by nitric acid and sulfuric acid,and lead sulphate was formed.Lead sulphate was separated from other elements,and dissolved in acetic acid-ammonium acetate buffer solution. Lead was titrated by EDTA with xylenol orange as indicator,and the lead content in sample was calculated according to EDTA consumption volume.The detection limit of lead in samples was 2%.Three lead ores and four lead concentrates were determined by this method.The relative standard deviations of determination results were 0.32%-0.71% and 0.18%- 0.30%(n=8),respectively,and the recoveries were 97%-101% and 97%-103%,respectively.The method was applied to the determination of lead in national standard substances for lead ore and lead concentrate,the results were basically consistent with the national standard method,and the relative errors were not more than 0.052%.The method is simple,rapid,accurate and precise,and it can meet the needs of rapid detection of lead ore and lead concentrate samples.