黄铁矿
含水层
碳酸盐
浸出(土壤学)
溶解
地下水
铀
尾矿
环境化学
地球化学模拟
碳酸盐矿物
地质学
矿物学
地球化学
化学
土壤科学
冶金
土壤水分
材料科学
岩土工程
有机化学
物理化学
作者
Chongsheng Lu,Wei Xiu,Huaming Guo,Guoxi Lian,Bing Yang,Tianjing Zhang,Erping Bi,Zheming Shi
摘要
Abstract Although neutral in situ leaching through CO 2 + O 2 is employed to extract uranium (U) in sandstone by in situ leaching (ISL), mechanisms of U mobilization and O 2 consumption remained unclear. To address this gap, 18 groundwater samples were taken from the Qianjiadian sandstone U ore field, including seven samples from production wells in mining area M1 (mining for 5 years), six samples from production wells in mining area M2 (mining for 4 years), and five samples from monitoring wells (GC), to quantify U‐mobilizing processes in the mining aquifer by employing hydrogeochemical compositions and multi‐isotopes. The introduction of O 2 and CO 2 efficiently stimulated U mobilization in the mining aquifer. The injected CO 2 critically promoted the dissolution of carbonate minerals, which enhanced the formation of uranyl carbonate (predominantly CaUO 2 (CO 3 ) 2 2− and Ca 2 UO 2 (CO 3 ) 3 (aq)) and thus facilitated U mobility. Generally, δ 34 S SO4 and δ 18 O SO4 in M2 and M1 were significantly lower than those in GC ( p < 0.01). A Bayesian isotope mixing model of δ 34 S SO4 and δ 18 O SO4 showed that the contribution of pyrite oxidation to SO 4 2− concentration increased from 1.7% in GC to 13.6% in M2 and to 15.0% in M1. During ISL, pyrite, ammonium, and dissolved organic carbon were major compounds competing with U(IV) for introduced O 2 in the ore‐bearing aquifer. Most of the consumed O 2 was used for pyrite oxidation (56.2%) and U(IV) oxidation (39.3%), following the thermodynamic sequence of those redox reactions. The current results highlighted the significance of increasing O 2 utilization efficiency in improving the performance of ISL operations.
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