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：
1649656
负责人：
Alexander Gysi
金额：
$ 32.84万
依托单位：
Colorado School of Mines
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-01-01 至 2020-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1649656&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使用的最关键元素之一。矿物质异种 - （Y）和独居石 - （Ce）是常见的矿物质，在地壳中包含这些稀土元素（REE）。除了它们的社会相关性外，REE轴承矿物（磷酸盐）已被证明是限制地壳过程的时机和温度的重要地质示踪剂。在不同地质环境中从REE磷酸盐中检索信息的全部潜力刚刚开始探索，REE矿物质的特性在寻找关键金属的经济兴趣中增加了经济利益，这些金属在新兴的高科技和绿色工业中都起着重要作用。拟议的研究将实验室实验与数值建模相结合，用于构建一种新的热力学流体矿物质固体溶液模型，该模型可以应用于地质环境中的矿石沉积物和变质/变质过程。这项研究将通过在开放式矿山热力学数据库（http://tdb.mines.edu/）中实施所得数据来传播，并且将在专用网页上提供一组教育建模项目。 REE矿藏和数值建模的简短课程将在科罗拉多州矿业学院（CSM）组织，以介绍该数据库的应用。该项目还将通过支持调查员的新地壳液体摇滚实验室来促进一名早期职业科学家，在那里他将培训2名研究生，并参与CSM和/或巴西科学流动性计划的夏季本科生。使用数值模拟，团队将预测地壳中矿物和流体的稳定性，这是压力和温度的函数，并根据实验和新的理论模型扩展这些功能。我们目前对REE在水性流体和矿物质中的行为的理解受到REE矿物质固体溶液的可用热力学数据的限制。提出的工作将结合实验室矿物质溶解度和量热实验，以确定二元磷酸盐固体溶液混合的焓，最终成员的溶解度及其热能。这将允许构建一个内部一致的热力学数据集，该数据集将在Gibbs Energy最小化程序中实现，并应用于研究水热REE矿物质沉积物的起源。该项目将尝试在变质岩石学和地球化学之间跨越边界，并有望对地壳液中REE的行为产生影响。可以扩展这些知识以确定主要配体对地壳中金属迁移率的影响，并且可以将辅助矿物固体溶液组成的组成在变质过程中跟踪转移阶段。