砂岩铀矿成矿过程中有机质作用的实验研究——以吐鲁番—哈密盆地十红滩铀矿床为例

An Experiment Study on the Role of Organic Materials in Ore-forming of Sandstone-type Uranium Deposit-A Case Study of the Shihongtan Deposit, Turpan-Hami Basin

本文利用采自吐鲁番—哈密盆地西南部的样品,有针对性地做了一系列有机质抽提及分离实验,即 ① 利用氯仿抽提岩石中有机质实验;② 利用CS_2—NmP(二硫化碳—N-甲基-2吡咯烷酮)抽提岩石中有机质实验;③ 腐殖质提取及分离实验。以上有机质抽提物及分离物分别做铀含量测试。通过实验发现,按以上实验顺序,岩石有机质提取物或分离物中铀含量依次有不同程度的提高,其中以腐殖质中分离出的黄腐酸(Fulvic acids)中铀含量最高,说明在吐哈盆地西南部砂岩铀矿的形成过程中有机质(主要是腐殖质和沥青质)的吸附作用起到部分作用,起最主要作用的是黄腐酸,而且与铀酰离子是以络合(或螯合)形式进行迁移。通过实验和分析,作者认为腐殖质(Humic substances)的络合作用和吸附作用在铀的迁移过程中是紧密相联的,而不是互相孤立的两种作用。在铀的迁移和沉淀富集过程中,黄腐酸(Fulvic acids)和腐殖酸(Humic acids)分别起到不同作用。

A series of experiments have been made on samples collected from the Shihongtan deposit, southwestern part of the Turpan-Hami Basin in northwestern China, i. e. (1) Extracting organic matter from rocks with CHC13; (2) Extracting organic matter from rocks with CS2-NmP; and (3) Humic substance extracting and separation. Uranium content was analyzed in the extracted organic matters. It was found that the uranium content level in these matters increased to some extent in accordance with the above experimental sequence, with the fulvic acids having the highest uranium content. It illustrates that in the course of uranium deposit formation, the organic (humic substance and bentum ) adsorption plays a partial role. The major player is fulvic acid (FA), which migrates in the form of complexing with uranyl. From the experiment and analysis, the authors believe that the complexing and adsorption of humic substance (humus) are closely linked in the course of uranium migration.