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本文介绍了矿石、精矿、锍和硅酸盐与铁系岩石中10~(-6)与10~(-9)含量的贵金属(除锇外)的两种测定方法。用氢氟酸和王水分解试样后,随即把任何不溶渣与过氧化钠一起熔化,用阳离子交换法或与碲共沉淀法,使贵金属与脉石元素分离。把所得洗脱液或碲沉淀物溶解后获得的溶液蒸发至干,最后,在1M盐酸介质中,用石墨炉原子吸收光谱法测定贵金属。推荐用离子交换法测定10~(-6)含量的金、银与铂族金属,同时,推荐碲共沉淀法测定10~(-9)含量的铂族金属。不推荐后一种方法测定岩矿中10~(-9)级的银与金,因为在石墨炉内雾化时,碲会发生干扰。用这些方法获得的15种国际参考样品(包括4种加拿大铁系岩矿)的结果与其它发表的数据作了比较。
This paper presents two methods for the determination of noble metals (except osmium) of 10 ~ (-6) and 10 ~ (-9) in ores, concentrates, sulfonium and silicates and iron rocks. After the sample is decomposed with hydrofluoric acid and aqua regia, any insoluble slag is immediately melted with sodium peroxide, and the noble metal is separated from the gangue elements by cation exchange or coprecipitation with tellurium. The solution obtained after dissolving the resulting eluate or tellurium precipitate is evaporated to dryness and finally the noble metal is determined by graphite furnace atomic absorption spectrometry in 1M hydrochloric acid medium. It is recommended to measure the content of 10 ~ (-6) gold, silver and platinum group metals by ion exchange method. Meanwhile, tellurium coprecipitation method for the determination of platinum group metal with 10 ~ (-9) content is recommended. The latter method is not recommended for the determination of 10-9 grade silver and gold in rock and mine because tellurium interferes with the atomization in graphite furnaces. The results of 15 international reference samples obtained using these methods, including four Canadian iron-type rocks and mines, were compared with other published data.