重铬酸钾滴定法测定废杂铜中的铁含量

研究了废杂铜中铁含量的测定方法。试料采用盐酸、硝酸、高氯酸溶解,加入过量氨水生成氢氧化铁沉淀与铜、铬等干扰元素分离,沉淀用热盐酸溶解后,用氯化亚锡还原至溶液呈浅黄色,重铬酸钾滴定法测定铁含量。探讨了溶样方式、氯化铵用量、氨水过量的体积、硫磷混酸用量对测定结果的影响。对4个废杂铜样品中的铁含量进行测定,测定结果的相对标准偏差RSD(n=11)为0.38%～0.95%,加标回收率为99.4%～100%,方法准确可靠,能够满足测定要求。

Determination of Iron in Scrap Copper by Dichromate Titration Method

The determination method of iron content in scrap copper was studied. The samples are dissolved by hydrochloric acid, nitric acid and perchloric acid, and added with excessive ammonia to form ferric hydroxide precipitation and separated from interfering elements such as copper, chromium and other interfering elementsc. The precipitate is dissolved with hot hydrochloric acid, and the stannous chloride is used for reduction until the solution is reduced to pale yellow, then titrate with potassium dichromate to determine the content of iron. The influence on the determination was discussed including the method of sample dissolution, the amount of ammonium chloride, the excess volume of ammonia and the amount of sulfur-phosphorus mixed acid. According to the method, the content of iron in four scrap copper samples was determined. The relative standard deviation (RSD) of the method was 0.38 %~ 0.95%, and the recovery rate of the sample was between 99.35 %~ 100.17 %. The method is accurate and reliable, which is suitable for the determination of iron content in scrap copper.