Thermodynamics of Rare Earth Minerals

稀土矿物的热力学

• 批准号: 1321410
• 负责人: Alexandra Navrotsky
• 金额: $ 30万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-01 至 2016-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1321410&HistoricalAwards=false
• 关键词: Thermodynamics; Rare; Earth; Minerals

Rare earth elements are critical to materials used in technologies ranging from magnets to batteries to LED lighting. They are considered 'critical' materials in the sense that such technologies cannot work without them and, at the same time, their supply is limited and/or subject to geopolitical manipulation. The source of rare earths, as of all elements, is the Earth, and a variety of rock types are mined for these elements, which must then be concentrated, separated, and purified. These rocks (ores) contain a variety of host minerals, which typically contain rare earths in low concentrations in complex minral structures together with other elements such as uranium, thorium and niobium. Though the thermodynamic properties of these multicomponent mineral solid solutions define their formation and occurrence in the Earth and constrain processes for the mining, processing, and purification of the rare earth elements, these properties are poorly known at present. This project entails a systematic study of the thermodynamics of formation of a selected set of synthetic rare earth materials in order to understand the effects of different rare earths and other elements, as well as of the structures, on stability. The results will provide fundamental data for more complete, efficient, and economical extraction and separation of rare earths from mineral sources, thus fulfilling the Sustainable Chemistry, Engineering, and Materials (SusChEM) objectives. At the same time the data will be useful in modeling the transport of rare earths in the geologic environment, the origin of rare earth deposits, and the use of rare earths as geochemical indicators in petrologic processes. High temperature oxide melt solution calorimetry, a specialized technique tailored to determing heats of formation of refractory oxide systems, will be used to measure heats of formation of selected systems. The samples will be synthesized and characterized extensively prior to calorimetry. The overall goal is to quantify the thermochemistry of charge-balanced ionic substitutions of rare earths in minerals. Phases in the RE2O3- H2O- CO2- HF system, including the major rare earth ore bastnasite, will be studied. The enthalpies of formation and mixing of RE solid solutions in perovskite and pyrochlore systems will be characterized.

稀土元素对于从磁铁到电池再到LED照明的技术中使用的材料至关重要。它们被认为是“关键”材料，从某种意义上说，这些技术无法没有它们，同时它们的供应受到限制和/或受地缘政治操纵的约束。 在所有元素中，稀土的来源是地球，为这些元素开采了多种岩石类型，然后必须将其集中，分离和纯化。这些岩石（矿石）含有各种寄主矿物质，通常在复杂的微小结构中以低浓度的稀土以及其他元素（例如铀，thor和niobium）中的稀有土。 尽管这些多组分矿物固体溶液的热力学特性定义了它们在地球中的形成和发生，并限制了稀土元素的采矿，加工和纯化的过程，但这些特性目前是鲜为人知的。该项目需要进行一项系统的研究，对一组合成稀土材料的形成热力学，以了解不同的稀土和其他元素以及结构对稳定性的影响。结果将提供基本数据，以更完整，有效，经济的提取，并将稀土与矿物质源分离，从而实现可持续的化学，工程和材料（SUSCHEM）目标。同时，数据将在地质环境中建模稀土的运输，稀土沉积物的起源以及将稀土作为岩石学过程中的地球化学指标的使用。高温氧化物熔体溶液量热法是一种专门的技术，该技术量身定制，用于确定难治氧化物系统形成热的热量，用于测量所选系统形成的热量。样品将在量热法之前进行广泛合成和表征。总体目标是量化矿物质中稀土电荷平衡离子取代的热化学。将研究RE2O3-H2O-CO2-HF系统中的相位，包括主要的稀土矿石bastnasite。将表征钙钛矿和pyrochlore系统中固体溶液的形成和混合的焓。