黑色岩型铂族矿物中铂钯金相态ICP-MS分析方法研究

Phase Analysis of Pt,Pd and Au in Black Rock-type Platinum Group Element Minerals by ICP-MS

黑色岩是近年发现的铂族元素重要载体,由于其金属来源的多样性及成矿作用的复杂性,对于铂族元素在该类矿物中的分布及富集形式目前并不十分清楚,这也是造成黑色岩中铂族元素测定不稳定的主要原因。本文根据黑色岩的矿物性质及组成,将黑色岩中Pt、Pd、Au的赋存状态划分为:可交换相、有机结合相、硫化物结合相、残渣相。通过应用硫氰酸钾+氰化钠作为解吸剂,有效抑制了黑色岩中有机碳对各相态中Pt、Pd、Au的吸附,采用分离富集ICP-MS法测定了Pt、Pd、Au在各相态中的分布。结果表明:(1)各元素各相态的提取总量与该元素在样品中的总量之比分别为Pt 94.4%~101.0%,Pd 95.8%~101.0%,Au 96.7%~102.0%,说明本方法具有较好的准确性和重现性;(2)黑色岩矿物中Pt、Pd、Au的富集不仅具备亲硫性,而且与有机碳形成的地质条件、地质背景有明显的相关性,此结果为研究黑色岩中铂族元素所处的地球化学环境及其成矿规律提供了重要信息。

Black rock as an important carrier of platinum group elements was discovered in recent years. Due to the multiple origins and complex mineralization, the distribution and occurrence of platinum group elements in black rock are not clear, which is also the major reason why the analytical results of platinum group elements are unstable.According to the mineral properties and composition of black rock, the occurrences of Pt, Pd and Au in black rock could be divided into exchangeable phase, organic, bindingphase, sulfide bounding phase, and residue phase. The adsorption of Pt, Pd and Au from the organic carbon in black rocks was inhibited by adding potassium thiocyanate and sodium cyanide as desorbents. The distribution of Pt, Pd and Au in each phase was identified by Inductively Coupled Plasma-Mass Spectrometry （ICP-MS）. The results show that ： （1） The ratios of the total extraction of each phase to the total amount of the element are 94.4% -101.0% for Pt, 95. 8% - 101. 0% for Pd, and 96. 7% - 102. 0% for Au, indicating good accuracy and reproducibility. （2） The enrichment of Pt, Pd and Au in black rock minerals not only shows the chalcophile affinity, but also shows obvious correlation with the geological conditions and geological setting of organic carbon formation. The results provide important information for studying the geochemical environment and the metallogenic regularity of the platinum group elements in black rocks.