太平洋富钴结壳中稀土元素的赋存状态

OCCURRENCE MODES OF REE IN THE PACIFIC COBALT-RICH CRUSTS

采用化学提取方法对采自太平洋国际海域的板状和结核状富钴结壳的稀土元素进行了分级提取 ,并利用等离子质谱仪 (ICP MS)测定了稀土元素的质量分数。结果表明 ,结壳中稀土元素在不同结合态中的富集顺序为 :残渣态 >有机结合态 >锰氧化物结合态 >碳酸盐结合态 >吸附态。稀土总质量分数的 5 6 %以上集中在残渣态中 ,并主要赋存于非晶态FeOOH物相中 ,说明FeOOH的形成对稀土元素的富集具有重要作用。水羟锰矿占结壳中X衍射结晶矿物的 95 %以上 ,但其稀土质量分数仅占稀土总质量分数的 1 6 %左右。呈有机结合态的稀土元素含量约占结壳稀土总质量分数的 2 0 % 。

Chemical extraction has been utilized to fractionally extract rare earth elements in plate and nodular cobalt-rich crusts in the international sea-bed area of the Pacific Ocean, and an Inductively Coupled Plasma-Mass Spectrograph(ICP-MS) has been used to determine the content of rare earth elements in the different phases. The results show that the enrichment of rare earth elements in different phases conforms to the following order: residual phases>organic phases>manganese oxide phases>carbonate phases>adsorbate. More than 56% of total rare earth content is concentrated in the residual phases, and most of these elements occur in amorphous FeOOH, which indicates the significance of FeOOH formation on rare earth elements enrichment. According to the X-ray diffraction analysis, more than 95% of crystalline minerals in the crusts are vernadite, whereas the rare earth content of the phase is just about 16% of the total rare earth content. The rare earth element contents in organic phase is about 20% of the total content. These results indicate that the organic matters are of significant impacts on the formation of the crust and the enrichment of the rare earth elements in these crusts.