铅试金重量法测定铜精矿中金和银

Determination of gold and silver in copper concentrate by lead fire assaying gravimetric method

采用铅试金重量法测定铜精矿中的金和银时,因铜精矿中的铜含量较高,在高温熔融时,部分铜会与金和银一起保留在铅扣中,造成灰吹时铜会形成氧化铜渣从而使铅扣产生冻结现象进而影响测定。通过优化实验条件消除了试样中铜对测定的影响,最终实现了铅试金重量法对铜精矿中金和银的测定。探讨了铅试金时铅扣中铜量对灰吹效果的影响,结果表明,当铅扣中铜质量小于1g时,铜对金和银的测定结果无影响。对铅试金重量法测定铜精矿中金和银的条件进行了优化,结果表明,通过选择试样量为15g,配料中氧化铅量为135g、硅酸度为0.5,可有效的将铅扣中的铜量控制在1g以下,据此消除了试样中铜对测定的影响。考察了灰吹温度对金和银测定结果的影响,确定灰吹温度为860℃。方法应用于铜精矿实际样品分析,分析结果与国家标准方法 GB/T 3884.1—2012吻合。按实验方法分别对2个铜精矿样品平行测定7次,金测定结果的相对标准偏差(RSD)小于5%,银测定结果的相对标准偏差小于2%。

During the determination of gold and silver in copper concentrate by lead fire assaying gravimetric method,partial copper would be retained in lead button together with gold and silver in high temperature melting process due to the high content of copper.As a result,copper could be converted to copper oxide slag in cupellation,leading to congelation phenomenon of lead button which influenced the determination.The influence of copper in sample on determination was eliminated by optimizing the experimental conditions,then the determination of gold and silver in copper concentrate by lead fire assaying gravimetric method was realized.The effect of copper content in lead button on cupellation in lead fire assaying was discussed.The results showed that copper had no influence on the determination of gold and silver when the content of copper in lead button was less than 1 g.The determination conditions of gold and silver in copper concentrate by lead fire assaying gravimetric method were optimized.The results showed that the content of copper in lead button could be effectively controlled below 1 g under the following conditions：the sampling amount was 15 g,the lead oxide content was 135 g and the silicate degree was 0.5,thus the influence of copper in sample on determination could be eliminated.The effect of cupellation temperature on the determination results of gold and silver was explored.The cupellation temperature at 860℃ was finally selected.The proposed method was applied for the analysis of actual sample of copper concentrate,and the results were consistent with those obtained by national standard method GB/T 3884.1—2012.Two copper concentrate samples were determined according to the experimental method.The relative standard deviation（RSD,n=7）for gold and silver was less than 5% and 2%,respectively.