火试金留铅灰吹法测定银精矿中的银

采用火试金法测定银精矿中的银时,由于银在灰吹过程中损失,造成银回收率在98.9%左右。实验在临近灰吹终点时,留下少量的铅珠,水冷法取出,硝酸溶解后利用硫氰酸钾滴定。通过条件优化实验获得最佳灰吹温度为880℃,留铅量为2.0~3.0 g,且样品中银量越低,银损失率越高。火试金留铅灰吹法测定结果相对标准偏差小于1.50%,银回收率高于非留铅灰吹法,为99.83%。该方法减少了银在灰吹中的损失,测定结果更加准确。

Determination of silver in silver concentrates by fire assay lead-retaining cupellation method

In the fire assay test of silver in silver concentrates,the general recovery of silver is about 98.9%due to the loss of silver in the cupellation process.In the experiment,a small amount of lead was left near the end of the cupellation process.The lead beads were extracted by water-cooling method and were dissolved by nitric acid before titrated with potassium thiocyanate.The results of conditional test show that the optimal cupellation temperature is 880℃,the amount of lead retained is 2.0-3.0 g and that less silver content in samples lead to higher silver loss rate.The RSD of the determination results is less than 1.50%.The recovery rate of silver 99.83%is higher than that of non-lead-retaining cupellation method.The method reduces silver loss in cupellation and the determination results are more accurate.