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A molecular dynamics study of Li speciation in hydrothermal fluids and silicate melts
Chemical Geology ( IF 3.6 ) Pub Date : 2021-09-17 , DOI: 10.1016/j.chemgeo.2021.120528
Tianhua Wang 1 , Xiaoyu Zhang 1 , Xiandong Liu 1 , Xiancai Lu 1 , Rucheng Wang 1
Affiliation  

Magmatic-hydrothermal ore-forming processes play an important role in the transport, enrichment and mineralization of Li. In this study, first principles molecular dynamics (FPMD) and classical molecular dynamics (CMD) techniques were employed to investigate the speciation of Li in silicate melts and hydrothermal fluids. FPMD results show that Li does not form stable ion pair with F or Cl in silicate melts, but forms four-fold Lisingle bondO coordination. Association constants of Li—F/Cl ion pairs in hydrothermal fluids under a wide range of T-P conditions (i.e., temperatures up to 1273 K and fluid densities ranging from 0.1 g/cm3 to 1.0 g/cm3) derived with constrained CMD show increasing stability with temperature increasing or fluid density decreasing. Together with previous studies on Na/K—F/Cl ion pairs, an association constant database is provided for alkali halides ion pairs. It is found that Lisingle bondF ion pair is dominant in geological vapors.



中文翻译:

热液和硅酸盐熔体中锂物种形成的分子动力学研究

岩浆-热液成矿过程在锂的输运、富集和成矿过程中起着重要作用。在这项研究中,第一性原理分子动力学 (FPMD) 和经典分子动力学 (CMD) 技术被用来研究锂在硅酸盐熔体和热液流体中的形态。FPMD 结果表明,Li 不与硅酸盐熔体中的 F 或 Cl 形成稳定的离子对,而是形成四重 Li 单键O 配位。Li-F/Cl 离子对在各种 TP 条件下(即温度高达 1273 K 和流体密度范围从 0.1 g/cm 3到 1.0 g/cm 3 )在热液中的缔合常数) 得到的约束 CMD 显示出随着温度升高或流体密度降低而增加的稳定性。结合先前对 Na/K-F/Cl 离子对的研究,提供了碱卤化物离子对的缔合常数数据库。发现Li 单键F离子对在地质蒸气中占主导地位。

更新日期:2021-09-28
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