The Thermodynamic Properties of Rare Earth Element (REE) Minerals: A Solid Solution Model for Xenotime-(Y) and Monazite-(Ce)

稀土元素 (REE) 矿物的热力学性质：磷钇矿 (Y) 和独居石 (Ce) 的固溶体模型

基本信息

批准号：
2032761
负责人：
Alexander Gysi
金额：
$ 5.25万
依托单位：
New Mexico Institute of Mining and Technology
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-06-01 至 2022-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2032761&HistoricalAwards=false
关键词：
Thermodynamic Properties Rare Earth Element

项目摘要

The Rare-Earth Elements (REE) are among the most critical elements used in a variety of new technological applications. The minerals xenotime-(Y) and monazite-(Ce) are common minerals that contain these rare earth elements (REE) in the Earth's crust. In addition to their societal relevance, REE bearing minerals (phosphates) have proven to be important geological tracers for constraining timing and temperatures of crustal processes. The full potential for retrieving information from REE phosphates in different geological settings has just begun to be explored, and the properties of REE minerals have gained an increased economic interest in the search for critical metals, which play this major role in emerging high technology and green industries. The proposed study combines laboratory experiments with numerical modeling for building a new thermodynamic fluid-mineral solid solution model that can be applied to the study of ore deposits and metamorphic/metasomatic processes in geological settings. This research will be disseminated by implementing the resulting data in the open access MINES thermodynamic database (http://tdb.mines.edu/), and a set of educational modeling projects will be provided on a dedicated webpage. A short course on REE mineral deposits and numerical modeling will be organized at the Colorado School of Mines (CSM) to introduce the application of this database. This project will also promote an early career scientist by supporting the investigator's new crustal fluid-rock laboratory, where he will train 2 graduate students and involve summer undergraduate students from CSM and/or the Brazil Scientific Mobility program. Using numerical simulations, the team will predict the stability of minerals and fluids in the Earth's crust as a function of pressure and temperature, and expand these capabilities based on experiments and new theoretical models. Our current understanding of the behavior of REE in aqueous fluids and minerals is limited by the paucity of available thermodynamic data for REE mineral solid solutions. The proposed work will combine laboratory mineral solubility and calorimetric experiments to determine the enthalpy of mixing of binary REE phosphate solid solutions, the solubility of end members and their heat capacities. This will permit building an internally consistent thermodynamic dataset that will be implemented in the Gibbs energy minimization program GEMS, and applied to study the genesis of hydrothermal REE mineral deposits. The project will attempt to cross boundaries between metamorphic petrology and geochemistry, and is expected to have an impact for the interpretation of the behavior of REE in crustal fluids. This knowledge can be extended to determine the effects of major ligands on the mobility of metals in the crust, and may be applied to systems were the composition of accessory mineral solid solutions could be used to track metasomatic stages during metamorphism.

稀土元素 (REE) 是各种新技术应用中最关键的元素之一。磷钇矿 (Y) 和独居石 (Ce) 矿物是地壳中含有这些稀土元素 (REE) 的常见矿物。除了其社会相关性之外，含稀土矿物（磷酸盐）已被证明是限制地壳过程的时间和温度的重要地质示踪剂。从不同地质环境中的稀土磷酸盐中检索信息的全部潜力刚刚开始被探索，稀土矿物的特性在寻找关键金属方面引起了越来越多的经济兴趣，这些金属在新兴高科技和绿色环保中发挥着重要作用行业。拟议的研究将实验室实验与数值建模相结合，建立一种新的热力学流体-矿物固溶体模型，该模型可应用于地质环境中矿床和变质/交代过程的研究。这项研究将通过在开放获取的 MINES 热力学数据库 (http://tdb.mines.edu/) 中实施所得数据来传播，并将在专用网页上提供一组教育建模项目。科罗拉多矿业学院（CSM）将举办有关稀土矿床和数值模拟的短期课程，介绍该数据库的应用。该项目还将通过支持研究人员的新地壳流体岩石实验室来促进一名早期职业科学家的发展，他将在那里培训 2 名研究生，并让来自 CSM 和/或巴西科学流动项目的暑期本科生参与进来。通过数值模拟，该团队将预测地壳中矿物质和流体的稳定性随压力和温度的变化，并根据实验和新的理论模型扩展这些能力。我们目前对稀土元素在水性流体和矿物中行为的理解受到稀土元素矿物固溶体可用热力学数据缺乏的限制。拟议的工作将结合实验室矿物溶解度和量热实验，以确定二元稀土磷酸盐固溶体的混合焓、端元的溶解度及其热容。这将允许建立一个内部一致的热力学数据集，该数据集将在吉布斯能量最小化计划 GEMS 中实施，并应用于研究热液稀土矿床的成因。该项目将尝试跨越变质岩石学和地球化学之间的界限，预计将对地壳流体中稀土元素行为的解释产生影响。这些知识可以扩展到确定主要配体对地壳中金属迁移率的影响，并且可以应用于辅助矿物固溶体的组成可用于跟踪变质过程中的交代阶段的系统。