基于过筛预处理提高重砂中金量的测定准确性探讨  

Discussion on the improvement of determination accuracy of gold content in heavy sand based on screening pretreatment

作　　者：郝明阳 芦新根 陈永红 赵凯 HAO Mingyang;LU Xin′gen;CHEN Yonghong;ZHAO Kai(Changchun Gold Research Institute Co.,Ltd.,Changchun 136000,China)

机构地区：[1]长春黄金研究院有限公司,吉林长春136000

出　　处：《冶金分析》2024年第3期77-83,共7页Metallurgical Analysis

摘　　要：重砂中存在少量大颗粒金,造成金品位极不均匀,为其金含量的测定增加了一定的难度。试验基于过筛预处理方法改进常规取样方式,使筛下样品金量均匀性大幅提高,进而增加取样代表性。并通过探究样品磨制过程颗粒金粒径及形态变化规律,优化样品磨制条件,提高过筛处理效果,进而提高重砂样品测定准确性。试验表明:将重砂进行过筛预处理,筛下样品经多次火试金重量法(以下简称火试金法)测定金量,相对标准偏差(RSD)最小可达1.10%,明显低于未经过筛样品相对标准偏差9.66%。通过筛下样品取2~3份、筛上样品取全量测定再计算样品中平均金量的方法,可有效提高重砂中金含量测定准确性,避免多次测定取平均值方法造成的成本浪费;综合考虑过筛难度、筛上样品质量、筛下样品均匀性等因素,选择200目(74μm)为最优过筛目数;在500 g样品棒磨7 h后,巨粒金及粗粒金发生断裂进入到筛下,造成筛下样品均匀性变差,为使筛下样品金量均匀性达到最高,样品研磨程度不宜过高;过筛处理过程样品质量及金量损失较少,对检测结果准确性影响可忽略不计。方法可适用于火试金检测实验室。There is a small amount of large grain gold in the heavy sand,leading to the nonuniformity of gold grade,which increases the difficulty for determination of gold content.In this paper,the conventional sampling mode was improved based on the screening pretreatment method.The uniformity of gold content in sieved sample was greatly improved,thus enhancing the sampling representativeness.Through exploring the change rule of grain size and shape of gold particles in the sample grinding process,the grinding conditions were optimized,the screening treatment effect was improved,thereby improving the determination accuracy of heavy sand sample.The experiments showed that the gold content of in sieved sample was determined by multiple fire assay-gravimetric method(hereinafter referred to as fire assay)after screening pretreatment of heavy sand,and the minimum relative standard deviation(RSD)was 1.10%,which was obviously lower than that without screening pretreatment(i.e.,9.66%).2-3 sieved samples and total samples on sieve were used for determination,then the average gold content in sample was calculated.It could effectively improve the determination accuracy of gold content in heavy sand,and also avoid the cost waste caused by multiple determination to obtain the average value.The factors of screening difficulty,sample mass on sieve and the uniformity of sieved sample were considered comprehensively.The optimal sieving parameter was 200 mesh(74μm).When 500 g of sample was ground for 7 h in rod mill,giant grain gold and coarse grain gold would be ruptured and passed the sieve,deteriorating the uniformity of sieved sample.The grinding extent of sample could not be too high in order to guarantee the uniformity of sieved sample.The loss of sample and gold was little in screening pretreatment process,and it had little influence on the accuracy of determination results.The proposed method was applicable for the fire assay testing laboratories.

关 键 词：重砂 筛分 磨制样 火试金 均匀性 颗粒金 

分 类 号：O655.1[理学—分析化学] TF831[理学—化学]