贵州铜仁坝黄磷矿中铀赋存状态的逐级化学提取研究

贵州铜仁坝黄磷块岩矿床富集放射性元素铀,利用逐级化学提取分析方法对该地区黄磷矿中铀的赋存状态进行探究,有助于进一步探讨磷块岩型铀矿的分布规律、成矿机理及铀资源的综合开发。本文采用经修改的Tessier法流程,提取了水溶态、可交换离子态、碳酸盐结合态、铁锰氧化物结合态、有机质黄铁矿态、强酸提取态和残渣态等七种不同形态的铀。研究发现:黄磷矿中的铀主要以独立铀矿物和类质同象置换的形式存在,分别占37.83%、37.21%,少量铀(占24.96%)以分散吸附形式存在。分析表明:独立铀矿物在富磷、黄铁矿脉和镜面擦痕发育的岩层中含量较高,说明热液活动有利于独立矿物形式铀的富集;类质同象铀与黄磷矿中的磷含量呈正相关关系,铀元素可能是以离子置换的方式赋存于胶磷矿的晶格缺陷中;吸附形态铀的含量受到岩石中黏土矿物含量和黄铁矿脉的影响,有机质黄铁矿态是吸附形态铀存在的主要方式,少量铀通过扩散作用吸附于黏土矿物表面。除类质同象铀因其存在形式不易被提取利用外,独立铀矿物及吸附形态铀对于未来优化资源配置具有现实意义。

Stepwise Extraction Study on the Occurrence of Uranium in Tongren Bahuang Phosphorite, Guizhou

BACKGROUND: Previous studies have found that phosphorite deposits in Tongren Bahuang of Guizhou Province is rich in the radioactive element uranium.BAOBJECTIVES:To investigate the distribution regularity of phosphorite type uranium deposits, the metallogenic mechanism, and comprehensive development of uranium resources, by using the stepwise chemical extraction method to analyze the occurrence of uranium.METHODS:The modified Tessier process was used to extract seven different forms of uranium, including water-soluble, exchangeable ion, carbonate-bound, iron-manganese combined, organic-pyrite combined, strong acid and residual.RESULTS:The uranium in the phosphorite deposits occurs mainly in the form of independent uranium minerals and metamorphosed isomorphisms, accounting for 37.83% and 37.21%, respectively, and a small amount of uranium (24.96%) exists in the form of dispersed adsorption. The results show that the content of independent uranium minerals in the P-rich rocks, pyrite veins and specular surface is higher, which indicates that the hydrothermal activity is beneficial to the enrichment of uranium in the form of independent minerals. The isomorphism uranium is positively correlated with the content of phosphorus, and the uranium element may be deposited in the lattice defects of colloidal phosphate in the way of ion-substitution. The content of the adsorbed uranium is affected by the clay mineral content and pyrite vein in the rock. The organic matter pyrite state is the main state of the adsorbed uranium. A small amount of uranium adsorbed on the surface of clay minerals by diffusion.CONCLUSIONS:In addition to the fact that the isomorphous uranium is not easy to extract and utilize due to its existing form, independent uranium minerals and adsorbed uranium have practical significance for optimizing the resource allocation in the future.