CO_(2)和O_(2)共注入下方解石溶解对黄铁矿氧化固铀的影响  

Effect of Calcite Dissolution on Uranium Fixation by Pyrite Oxidation Under CO_(2)and O_(2)Co-injection Conditions

作　　者：王晶 王赛男 彭国建 张德 雷波 吕俊文 房琦 WANG Jing;WANG Sainan;PENG Guojian;ZHANG De;LEI Bo;LÜJunwen;FANG Qi(School of Resources Environment and Safety Engineering,University of South China,Hengyang,Hunan 421001,China;Beijing Institute of Nuclear Chemical Metallurgy,Beijing 100000,China;School of Computer/School of Software,University of South China,Hengyang,Hunan 421001,China)

机构地区：[1]南华大学资源环境与安全工程学院,湖南衡阳421001 [2]北京核工业化学冶金研究院,北京100000 [3]南华大学计算机学院/软件学院,湖南衡阳421001

出　　处：《南华大学学报（自然科学版）》2023年第5期20-27,共8页Journal of University of South China：Science and Technology

基　　金：国家自然科学基金资助项目(11705082,51874180,51704169);湖南省自然科学基金资助项目(2018JJ3434);湖南省教育厅科研资助项目(22A0303)。

摘　　要：我国大型可地浸砂岩型铀矿床普遍存在黄铁矿和方解石与铀矿物密切共生现象。中性地浸采铀过程中O_(2)和CO_(2)的共注入会诱导黄铁矿氧化和方解石溶解,目前针对二者共存体系中方解石溶解对黄铁矿氧化固铀的影响尚不明确。本文通过静态批实验和数值模拟的方法对比研究了CO_(2)和O_(2)条件下方解石溶解对黄铁矿氧化固铀的影响。结果表明:无CO_(2)分压下中性Tris缓冲体系中黄铁矿氧化对U(VI)的吸附率高达90%,有CO_(2)分压下碳酸铀酰体系中铀的固定率明显降低,约有32%的铀被吸附。在方解石和黄铁矿共存体系中,单独通O_(2)条件下铀的吸附率为27%,CO_(2)和O_(2)共通时黄铁矿氧化对铀的吸附率仅为2%,结合数值模拟结果表明O_(2)+黄铁矿+方解石体系和CO_(2)+O_(2)+黄铁矿+方解石体系中Ca_(2)(UO_(2))(CO_(3))_(3)质量比分别为80%和95%。X射线衍射(X-ray diffraction,XRD)、X射线光电子能谱(X-ray photoelectron spectroscopy,XPS)和傅里叶红外光谱(Fourier transform infrared,FT-IR)结果表明黄铁矿表面发生微氧化形成针铁矿和纤铁矿会增加U(VI)的吸附,方解石溶解促进Ca-UO_(2)-CO_(3)络合物的形成影响了黄铁矿及其氧化产物对U(VI)的固定,提高了U(VI)的迁移能力。Pyrite and calcite are closely associated with uranium minerals in large in-situ leachablesandstone-type uranium deposits in China.The co-injection of O_(2)and CO_(2)in the process of neutral in-situ leaching of uranium will induce pyrite oxidation and calcite dissolution.At present,the effect of calcite dissolution on pyrite oxidation and uranium fixation in the coexistence system of the two is not clear.In this paper,the effect of calcite dissolution on uranium fixation by pyrite oxidation under CO_(2)and O_(2)conditions was comparatively studied by static batch experiments and numerical simulations.The results showed that the adsorption rate of U(VI)by pyrite oxidation in neutral Tris buffer system without CO_(2)partial pressure was as high as 90%.The fixation rate of uranium in the uranyl carbonate system was significantly reduced under CO_(2)partial pressure,and about 32%of uranium was adsorbed.In the coexistence system of calcite and pyrite,the removal rate of uranium was 27%under the condition of O_(2)alone,and the removal rate of uranium by pyrite oxidation was only 2%when CO_(2)and O_(2)are combined.The numerical simulation results showed that Ca_(2)(UO_(2))(CO_(3))_(3)accounted for 80%and 95%of the O_(2)+pyrite+calcite and CO_(2)+O_(2)+pyrite+calcite systems,respectively.X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared(FT-IR)results showed that the formation of goethite and lepidocrocite on the surface of pyrite increased the adsorption of U(VI).The dissolution of calcite promoted the formation of Ca-UO_(2)-CO_(3)complex,which affected the fixation of U(VI)by pyrite and its oxidation products and improved the migration ability of U(VI).

关 键 词：黄铁矿氧化 方解石溶解 CO_(2)+O_(2) U(VI)赋存形态 U(VI)浸出质量浓度 

分 类 号：TL212[核科学技术—核燃料循环与材料]