CO_(2)+O_(2)浸铀体系铀的Eh-pH优势场分布特征

Pourbaix Diagram of Uranium in CO_(2)+O_(2) Leaching System of Sandstone Type Uranium Ore

铀的存在形式是决定铀的水迁移能力的重要条件。基于不同CO_(2)和O_(2)压力条件下的浸铀试验和地球化学模式软件PHREEQC计算,研究各浸铀体系中铀的Eh-pH优势场图特征及其影响因素。在CO_(2)+O_(2)浸铀体系中,碳酸铀酰络合物是铀在水中的主要存在形式,水的pH影响碳酸铀酰络合物优势域临界pH,HCO_(3)^(-)浓度则是铀的氧化还原临界电位变化的主控条件,而CO_(2)是这些影响产生的根本因素。

The state of uranium is an important condition that determines its migration ability in water.A data set from lab leaching experiments under different CO_(2)and O_(2)pressures were synthetically studied in geochemical model software PHREEQC,aiming to decipher influencing factors of Eh-pH field in uranium leaching system.The results show that,in CO_(2)+O_(2)leaching uranium system,uranyl carbonate complex is the main form of uranium in water,pH value of water affects the critical pH value of dominant domain of uranyl carbonate complex,and HCO_(3)^(-) concentration is the main controlling factor for change of uranium redox critical potential.It indicates that CO_(2)is the fundamental factor for these changes.