The Erlian Basin is an important production area of paleovalley-type sandstone uranium deposits in China, and its complete recharge-runoff-discharge system provides favorable hydrogeological conditions for the formation of uranium mineralization. Groundwater is a key medium for the migration and enrichment of elements in sandstone-type uranium deposits, and the chemical speciation of uranium in water is of great significance for studying the migration and enrichment processes of uranium as well as for in-situ leaching mining and metallurgy. Taking hydrogeological borehole data from the exploration of the Luhai Mining Area as the foundation, the study adopts aqueous speciation and equilibrium thermodynamic data of common major sandstone-type uranium minerals and relevant dissolved components. On this basis, the chemical speciation and concentration of uranium in local groundwater were calculated. It also simulated the variation rules of uranium chemical speciation under different conditions such as pH value, temperature and CO32− concentration, and constructed the Eh–pH phase diagram of the stable existing forms of uranium. The simulation results indicate that the uranium speciation in groundwater of Luhai Mining Area mainly exists in the forms of uranyl carbonate complexes such as UO2(CO3)22−, UO2(CO3)34− and UO2CO3(aq). pH exerts a significant influence on both the types and contents of uranium chemical speciation. Variations in temperature and CO32− concentration have a minor effect on the types of uranium chemical speciation but a considerable impact on their contents. The phase diagram of the U–C–O–H system shows that Uranium mainly exists in the form of U(Ⅵ) in oxidizing media, and its speciation changes with the variations in Eh, pH, ∑U and <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$P_{{{\text{CO}}_{{2}} }}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>P</mi> <msub> <mtext>CO</mtext> <mn>2</mn> </msub> </msub> </math></EquationSource> </InlineEquation> values. The results of this study will help clarify the migration and enrichment mechanisms of uranium in sandstone-type uranium deposits in Luhai area of Erlian Basin and provide a reference for identifying favorable metallogenic areas in the field.

Speciation distribution and thermodynamic simulation of uranium in groundwater of sandstone-type uranium deposits in Erlian Basin

期刊论文
发表日期：

2026年7月29日

查看全文

Tang Chao,
Meng Lishan,
Xu Zenglian,
Duan Ming,
Liu Huajian,
Wei Jialin

摘要

The Erlian Basin is an important production area of paleovalley-type sandstone uranium deposits in China, and its complete recharge-runoff-discharge system provides favorable hydrogeological conditions for the formation of uranium mineralization. Groundwater is a key medium for the migration and enrichment of elements in sandstone-type uranium deposits, and the chemical speciation of uranium in water is of great significance for studying the migration and enrichment processes of uranium as well as for in-situ leaching mining and metallurgy. Taking hydrogeological borehole data from the exploration of the Luhai Mining Area as the foundation, the study adopts aqueous speciation and equilibrium thermodynamic data of common major sandstone-type uranium minerals and relevant dissolved components. On this basis, the chemical speciation and concentration of uranium in local groundwater were calculated. It also simulated the variation rules of uranium chemical speciation under different conditions such as pH value, temperature and CO₃²⁻ concentration, and constructed the Eh–pH phase diagram of the stable existing forms of uranium. The simulation results indicate that the uranium speciation in groundwater of Luhai Mining Area mainly exists in the forms of uranyl carbonate complexes such as UO₂(CO₃)₂²⁻, UO₂(CO₃)₃⁴⁻ and UO₂CO₃(aq). pH exerts a significant influence on both the types and contents of uranium chemical speciation. Variations in temperature and CO₃²⁻ concentration have a minor effect on the types of uranium chemical speciation but a considerable impact on their contents. The phase diagram of the U–C–O–H system shows that Uranium mainly exists in the form of U(Ⅵ) in oxidizing media, and its speciation changes with the variations in Eh, pH, ∑U and $P_{{{\text{CO}}_{{2}} }}$ $P_{{CO}_{2}}$ values. The results of this study will help clarify the migration and enrichment mechanisms of uranium in sandstone-type uranium deposits in Luhai area of Erlian Basin and provide a reference for identifying favorable metallogenic areas in the field.