Abstract Rare earth elements (REEs) are critical materials having a wide variety of applications such as generating and storing renewable energy. Extracting rare earth metals from geothermal brines is a very challenging problem due to the low concentrations of these elements and engineering challenges with traditional chemical separations methods involving packed sorbent beds or membranes that would impede large volumetric flow rates of geothermal fluids passing through a geothermal power plant. We demonstrate a simple and highly cost-effective nanofluid-based method for extracting rare earth metals from geothermal brines. Core-shell composite nanoparticles that contain a magnetic iron oxide core surrounded by a shell made of metal-organic framework (MOF) sorbent functionalized with chelating ligands were produced to selectively extract rare earth elements. A flowsheet model is used to estimate the capital and operating cost of a potential process to extract Eu from geothermal brines in the Salton Sea area using the magnetic nanofluid technology. The techno-economic analysis (TEA) results show that the annual productivity of Eu from the outlet brine stream of a typical 20 MW geothermal power plant is about 2151 kg. The capital cost to apply the PNNL magnetic nanofluid technology is about $6.8 M and the internal return rate (IRR) for this investment is about 18.1% based on the information collected for the year 2018. Sensitivity analysis has been carried out for some key parameters such as the REE concentration and price and adsorbent cost to reveal their impacts on the IRR.

中文翻译：

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利用磁性核壳纳米粒子从地热卤水中提取稀土元素-技术经济分析

摘要 稀土元素 (REE) 是重要的材料，具有广泛的应用，例如产生和储存可再生能源。从地热卤水中提取稀土金属是一个非常具有挑战性的问题，因为这些元素的浓度低，而且传统化学分离方法涉及填充吸附剂床或膜的工程挑战会阻碍地热流体通过地热发电厂的大体积流量. 我们展示了一种简单且极具成本效益的基于纳米流体的方法，用于从地热卤水中提取稀土金属。核壳复合纳米粒子包含一个磁性氧化铁核，被一个壳包围，壳由金属有机骨架 (MOF) 吸附剂制成，用螯合配体官能化，以选择性地提取稀土元素。流程模型用于估计使用磁性纳米流体技术从索尔顿海地区的地热卤水中提取 Eu 的潜在过程的资本和运营成本。技术经济分析 (TEA) 结果表明，典型 20 MW 地热发电厂出口盐水流中 Eu 的年生产率约为 2151 kg。根据 2018 年收集的信息，应用 PNNL 磁性纳米流体技术的资本成本约为 680 万美元，该投资的内部回报率 (IRR) 约为 18.1%。