酸法地浸采铀过程中矿物组成变化对孔隙堵塞的影响

Effect of mineral composition change on pore blockage in the process of acid in-situ leaching of uranium

为了研究地浸采铀过程中矿物组成变化对孔隙堵塞的影响,以新疆某铀矿砂岩为例,借助灰色关联度理论分析了酸法浸出采铀过程中矿物组分变化对孔隙度与浸出铀浓度的影响。研究表明:(1)浸出过程中孔隙堵塞的原因主要是由于多种矿物在物理化学作用下的结果,它会影响铀矿砂岩中其他矿物的溶质运移过程,从而对矿物组成与铀浸出产生影响;(2)通过灰色关联分析发现孔隙堵塞对铀浸出的影响较大,硫酸钙与硅酸镁是对孔隙堵塞的主要原因,黏土矿物的物理吸附作用多表现在微孔方面,对大孔隙通道堵塞的影响要小于硅酸镁与硫酸钙。根据浸出过程中矿物组成变化规律与孔隙堵塞之间的关系,对地浸采铀工艺进行改进以解决孔隙堵塞问题,从而实现铀资源的高效开采。

[Background]In the process of in-situ leaching of uranium,pore blockage greatly limits the leaching efficiency of uranium,and the pore blockage is mainly due to the complex physical and chemical action of minerals and leaching agents in in-situ leaching of uranium.[Purpose]This study aims at the influence mechanism of each mineral composition on pore blockage under the action of leaching agent in the process of in-situ leaching of uranium to realize the efficient exploitation of uranium resources.[Methods]First of all,sandstones of uranium mine in Xinjiang were taken as the experimental samples,the relationship between the mineral composition and porosity in the process of acid in-situ leaching of uranium was studied through acid in-situ leaching experiment,and nuclear magnetic resonance experiment was employed every other period of time to obtain the porosity change curve in the process of uranium sandstone leaching.Then,the mineral characteristics of uranium sandstone were analyzed by X-ray diffractometer to find the changes of the mineral composition during uranium sandstone leaching.Finally,the influence of different minerals on porosity change was analyzed with the help of gray relational theory.[Results]The results show that the pore blockage in the leaching process is mainly due to the complex physical and chemical action of many kinds of minerals,which will affect the solute transport process of other minerals in uranium sandstone and not only lead to the change of mineral composition but also affect the leaching of uranium.Through grey correlation analysis,it is found that calcium sulfate and magnesium silicate as plugging materials have a correlation degree of over 0.781 for porosity and uranium leaching rate.The physical adsorption of clay minerals can block the micropores of uranium sandstone,so its correlation with porosity and uranium leaching is 0.831 and 0.842 respectively,indicating that pore plugging has an impact on uranium leaching.[Conclusions]According to the relationship between the change of mineral composition and pore blockage in the process of leaching,making appropriate adjustment can solve the problem of pore blockage,so as to realize the efficient exploitation of uranium resources.