EDTA容量法测定金精矿中锌方法的改进

Improved determination of zinc in gold concentrates by EDTA volumetric method

金精矿成分越来越复杂,采用国家标准方法测定锌量时,铅、铁等共存元素干扰严重。实验考察了铅的干扰、过滤次数、指示剂等影响因素,确定通过硫酸铅沉淀分离消除滴定过程中铅的干扰,二次过滤避免氢氧化铁沉淀对锌的吸附和包裹,二甲酚橙指示剂代替甲基橙指示剂调节p H使滴定终点更易分辨。该方法测定结果的相对标准偏差小于0. 80%,加入标准物质回收率为99. 40%～100. 25%,精密度好,准确度高,适用于金精矿中锌量的测定。

The composition of gold concentrate becomes more and more complicated.When zinc content is determined,the coexisting lead and iron elements severely interfere.Experiments are conducted to investigate the influence factors of lead interference,filter times and indicators and it is decided that lead sulfate precipitation is used to eliminate lead interference in titration,twice filtering to avoid zinc adsorption and inclusion by iron hydroxide precipitation,and xylenol orange in place of methyl orange as indicator to adjust pH in order to make titration endpoint more distinguishable.The RSD of determination results of the method is<0.80%.The recovery rate of the reference material is 99.40%-100.25%.The method is precise and accurate,applicable to zinc determination in gold concentrate.