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Study of the Behavior of Uranium, Niobium, and Tantalum in the Granite Melt–Fluoride Fluid System at 800–950°C, 2300 Bar
Geology of Ore Deposits ( IF 0.7 ) Pub Date : 2021-09-28 , DOI: 10.1134/s1075701521040073
A. F. Redkin 1 , Yu. B. Shapovalov 1 , V. I. Velichkin 2
Affiliation  

Abstract

Experimental studies were carried out on the solubility of uranium, niobium, and tantalum in acidic melts of Li–F granites and predominantly fluoride fluids at 800–950°С and 2300 bar, in order to clarify the genesis of ores in the unique Mo–U Streltsovska ore field (Eastern Transbaikalia). The experiments were carried out with a model homogeneous glass with the composition (wt %): 72.18 SiO2, 12.19 Al2O3, 1.02 FeO, 0.2 MgO, 0.33 CaO, 4.78 Na2O, 3.82 K2O, 1.44 Li2O, 2.4 F (LiF, NaF, KF, CaF2, MgF2), synthetic uranium dioxide, and natural columbite. The initial solutions contained 3.85 wt % chlorides and 5–30 wt % fluorides (Na, K, Li, Al, Si). The fugacity of O2(H2) was set by Co–CoO buffers and an Ar–H2 mixture. The solubility of Nb in F–Cl solutions depended on the concentration of the fluorides in their composition and ranged from 10–4–10–3 mol kg–1 H2O at 800°C and 10–3-10–2 mol kg–1 H2O at 950°C, while Ta is practically insoluble in the investigated solutions. The solubility of U is 10–4–10–2 mol kg–1 H2O. Electron microscope analysis of the products of experiments established that columbite dissolved incongruently in a granite melt with the formation of U- and F-bearing pyrochlores. The interaction of high-fluoride solutions in the region of fluid immiscibility with a granite melt leads to enrichment of the granite with alkalis, uranium, and niobium without significant introduction of fluorine.



中文翻译:

研究铀、铌和钽在 800-950°C、2300 巴下花岗岩熔体-氟化物流体系统中的行为

摘要

对铀、铌和钽在 800-950°C 和 2300 bar 的 Li-F 花岗岩酸性熔体和主要氟化物流体中的溶解度进行了实验研究,以阐明独特的 Mo- U Streltsovska 矿场(Eastern Transbaikalia)。该实验用模型均匀的玻璃与组合物(重量%)进行:72.18的SiO 2,12.19的Al 2 ö 3,1.02的FeO,0.2的MgO,0.33的CaO,4.78的Na 2 O,3.82ķ 2 O,1.44李2 O, 2.4 F (LiF, NaF, KF, CaF 2 , MgF 2)、合成二氧化铀和天然铌铁矿。初始溶液含有 3.85 wt% 的氯化物和 5-30 wt% 的氟化物(Na、K、Li、Al、Si)。O 2 (H 2 )的逸度由Co-CoO缓冲剂和Ar-H 2混合物设定。Nb 在 F-Cl 溶液中的溶解度取决于其组成中氟化物的浓度,范围为 10 –4 –10 –3 mol kg –1 H 2 O 在 800°C 和 10 –3 -10 –2 mol kg –1 H 2 O 在 950°C,而 Ta 几乎不溶于所研究的溶液。U的溶解度为10 –4 –10 –2mol kg –1 H 2 O。实验产物的电子显微镜分析表明,铌铁矿不协调地溶解在花岗岩熔体中,形成含 U 和 F 的烧绿石。流体不混溶区域中的高氟化物溶液与花岗岩熔体的相互作用导致花岗岩富含碱金属、铀和铌,而没有大量引入氟。

更新日期:2021-09-29
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