多金属共生锡矿石中铅的 EDTA 滴定法测定

摘要

The sample is dissolved with nitric acid and hydrochloric acid and heating up to fuming with sulfuric acid ,then removing arsenic ,antimony and tin from the solution with hydrobromic acid ,most of bismuth is separated with tartaric acid .The solution is filtered for separating coexisted elements .The filter residue is dissolves in acetic acid‐ammonium acetate buffer solution( pH is 5 .5 - 6 .0) ,then lead in the filtrate is determined by titrated with EDTA standard solution .The method can eliminate interferences when Bi ,W ,As ,Sb ,Sn in tin ore respectively is no greater than 20 mg .the lead recovery method is between 99 .9% and 100 .2% and the result is satisfaction .%研究了用 Na2 EDTA 标准溶液滴定测定多金属共生锡矿石中的铅。矿样用盐酸、硝酸溶解，用硫酸冒烟，用氢溴酸去除砷、锑、锡，以酒石酸络合大部分铋，过滤将硫酸铅与大部分共存元素分离，硫酸铅沉淀溶于pH 为5．5～6．0的乙酸‐乙酸铵缓冲溶液中，之后用二甲酚橙为指示剂进行滴定测定。共存干扰元素有 Bi 、W 、As 、Sb 、Sn ，对于50 mg 铅，这些元素质量均不大于20 mg 时，均不干扰测定，铅测定回收率达99．9％～100．2％，测定结果满意。