太平洋海山富钴结壳中铂族元素赋存状态与富集机理

摘要

Selective chemical extraction method was utilized to fractionally extract platinum group elements (PGE) in cobalt-rich crusts from Caiwei Seamount in the Pacific, and PGE contents were determined by inductively coupled plasma mass spectrometry (ICP-MS). Occurrence phase analysis results in cobalt-rich crusts show that the PGE enrichments in different phases conform to the following order: iron oxide phase, residual phase, manganese oxide phase, carbonate phase, adsorbed phase. PGE in the new non-phosphate layers and the old phosphate layers are mainly enriched in the iron oxide phase, with the enrichment ratio from 59.26% to 82.19%, and the phosphate in residual phase has certain enrichment ability for PGE, with the enrichment ratio from 17.23% to 35.37%. Mean-while, occurrence phase analysis results in different geological bodies show that the PGE enrichment in cobalt-rich crusts and seamount nodules is mainly affected by iron oxide phase and residual phase. In addition, the enrichment mechanism of PGE in cobalt-rich crusts is presumed to the iron oxide/iron hydroxides colloid particles adsorption, and the solublePtCl2?4in seawater is adsorbed into the iron oxide phase, so PGE are enriched in cobalt-rich crusts.%通过选择性化学提取法,对太平洋采薇海山富钴结壳样品中铂族元素进行分级提取实验,利用电感耦合等离子体质谱仪(ICP-MS)测定了铂族元素含量.赋存状态结果显示,富钴结壳中铂族元素在各个化学相态中富集比例从大到小依次为:铁氧化物相、残渣态、锰氧化物相、碳酸盐相、吸附态,未磷酸盐化新壳层和磷酸盐化老壳层中铂族元素都主要赋存于铁氧化物相中,其富集比例为59.26%～82.19%,残渣态中磷酸盐对铂族元素具有一定的富集能力,其富集比例为17.23%～35.37%.不同类型地质体中铂族元素的赋存状态结果,也证实了富钴结壳和海山结核中铂族元素富集主要受到铁氧化物相和残渣态的影响.太平洋海山富钴结壳中铂族元素的富集机理推测为铁氧/氢氧化物胶体粒子的吸附作用,使海水中PtCl2?4离子被吸附到铁氧化物相中,从而使富钴结壳中铂族元素富集.