USGS Publications Warehouse
USGS Publications Warehouse
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- منطقة بودونغ الجديدة ، شنغهاي ، الصين .
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About four billion years ago, Earth's outer layer is thought to have been composed mostly of a 25- to 50-km-thick basaltic crust that differentiated to form the …
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DR.J.R. PERUMAREDDI, in Modern Aspects of Rare Earths and Their Complexes, 2003. 3 Formation of lanthanide ores. Nature concentrates rare earth ores into useful ores by three processes. Minerals like monazite occur in small concentrations in common rocks that resist weathering and have high densities. They remain intact when their host rocks ...
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An elemental issue. By Russell Parman, U.S. Army Aviation and Missile Command September 26, 2019. 1 / 3 Show Caption + Technological applications of rare-earth elements have exploded over the past ...
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The only operating rare earths mine in the United States, for example, has been shipping its concentrate to China for refining. The DoD is investing $120m in a new plant for heavy rare earths ...
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Surfactant-based enrichment of rare earth elements from NdFeB magnet e-waste: Optimisation of cloud formation and rare earths extraction. Author links open overlay panel Ajay B. Patil a b 1 2, Nicole Thalmann a c 3, Laura Torrent a, Mohamed Tarik a 4, ... Cloud point extraction has been demonstrated for the rare earths enrichment. ...
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The estimated average concentration of the rare earth elements in the Earth's crust, which ranges from around 150 to 220 parts per million (table 1), exceeds that of many other metals that are mined on an industrial scale, such as copper (55 parts per million) and zinc (70 …
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Studying the speciation and mineral-fluid partitioning of the rare earth elements (REE) allows us to delineate the key processes responsible for the formation of economic REE mineral deposits in natural systems. Hydrothermal REE-bearing calcite is typically hosted in carbonatites and alkaline rocks, such as the giant Bayan Obo REE …
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Project objectives are: 1) to fully establish a comprehensive and robust geologic and geochemical framework for the occurrence of volcanic-related beryllium …
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Monazite is a rare phosphate mineral with a chemical composition of (Ce,La,Nd,Th) (PO 4,SiO 4 ). It usually occurs in small isolated grains, as an accessory mineral in igneous and metamorphic rocks such as granite, pegmatite, schist, and gneiss. These grains are resistant to weathering and become concentrated in soils and sediments downslope ...
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Rare Earth Elements in Australian Heavy Mineral Sands Deposits. Rare earths-bearing minerals monazite and xenotime occur in many of Australia's heavy mineral sand deposits and, up until the mid …
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New light has been shed on the formation of increasingly precious rare earth elements (REEs) by researchers from Trinity College Dublin. They accomplished …
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Carbonatites and related rocks are the premier source for light rare earth element (LREE) deposits. Here, we outline an ore formation model for LREE-mineralised carbonatites, reconciling field and petrological observations with recent experimental and isotopic advances. The LREEs can strongly partition to carbonatite melts, which are …
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With the development of the rare earths separation industry, there have been multifarious methods including chemical separation (fractional crystallization, fractional ... The compound extracts efficiently Er by formation of ErL 2 Cl, the extraction efficiency dissolved in CCl 4 was higher than in CH 2 Cl 2. Safarbali et al. [151] (2016) CR 4 ...
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The rare earths, often included as a group because they are chemically similar and commonly occur together, are often the first example used when discussing critical minerals. - Critical Minerals Below North Dakota's …
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Formation cause, formation volume, composition analysis and comprehensive utilization of the solid wastes of rare earth hydrometallurgy slag, electrolysis slag, Fe-based rare earth permanent magnetic materials, Co-based rare earth permanent magnetic materials, rare earth hydrogen storage materials, rare earth polishing powders …
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In association with researchers from the Department of Energy's National Energy Technology Laboratory (NETL) and analysts at mining consultancy International, metallurgical coal producer …
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When China began selling rare earths at very low prices in the late 1980s and early 1990s, mines in the United States were forced to close because they could no longer make a profit. [1] When China cut exports in 2010, rare earth prices skyrocketed. That motivated new production in the United States, Australia, Russia, Thailand, Malaysia, and ...
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Igneous ores at Mountain Pass and other major mines are mostly enriched in the "light" rare earths, resulting in overproduction and low prices for some elements and ongoing global supply ...
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It is significant that in the oldest rocks of the gneisses formation (dominate biotite-amphibole-hypersthene plagiogneisses) of early Archean age, monazite—one of the most important minerals in geological formations of the basement from area that contains rare earths—was found only occasionally, and zircon is found in form of small isolated ...
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Rare earths have the effect of hindering the formation and development of grain boundary wedge cracks, can hinder the precipitation of nitrides along grain boundaries, improve the lasting strength of steel such as Cr18Si2, Cr18Ni8N, Cr25Ni20 and Cr24Ni7N at different temperatures, strengthen grain boundaries and disperse impurity elements in ...
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The stepwise formation constants for complexes between the trivalent metals lanthanum, yttrium, and all of the rare earths, except promethium, and the ligands isobutyrate (IBU), alpha -hydroxyisobutyrate (AHIB) and alpha, BETA, BETA '-trihydroxyisobutyrate (THIB) were measured at 25 deg C and an ionic strength of 0.5M (NaClO/sub 4/).
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Regolith-hosted ion-adsorption deposits (IADs), formed by subtropical weathering of igneous rocks, are the world's primary source for heavy rare earth elements (HREEs, Gd-Lu and Y) 1, 2. These ...
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Some of the rare earths have standard free energy formation of their oxide higher than that of CaO. Similarly, the free energy of formation of rare earth halide is lower than the respective calcium halide. Hence, such halides or oxides had the potential to be reduced by calcium metal. The reaction is endothermic and hence there is a necessity ...
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The Phosphoria Formation is a part of the Western Phosphate Field which ranges from southern Montana to northern Utah. The Phosphoria Formation is composed of black shale deposits (Zapata, 2004). ... Rare Earths - A Brief Summary and Focus Elements - Seeking Alpha. Stock Market News & Financial Analysis - Seeking Alpha. Retrieved November 25 ...
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The rare earths are 17 metallic elements, located in the middle of the periodic table (atomic numbers 21, 39, and 57–71). These metals have unusual fluorescent, conductive, and magnetic properties—which make them very useful when alloyed, or mixed, in small quantities with more common metals such as iron. Geologically speaking, the rare ...
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High-performance magnets are a vital technology for building a zero-carbon economy, and the best permanent magnets currently available contain rare earth elements. Despite their name, rare earths …
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In this communication the values of the heats of formation obtained on alloys of rare earths with V degree group elements are summarized. This study is part of a systematic investigation on the ...
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Rare Earths Statistics and Information. Statistics and information on the worldwide supply of, demand for, and flow of the mineral commodity group rare earths - scandium, yttrium, …
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1. Introduction. Recently, the demand for rare earths has increased significantly, driving the development of new processes to recover rare earths from a variety of new resources (Long et al., 2010, Krebs and Furfaro, 2013, Pawlik, 2013).Among a large number of rare earth minerals, only three are mainly used for rare earth production, …
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The rare earth elements (REE) are fifteen elements with atomic numbers 57 through 71, from lanthanum to lutetium ("lanthanides"), plus yttrium (39), which is chemically similar to the lanthanide elements and thus typically included with the rare earth elements. Although industrial demand for these elements is relatively small in tonnage ...
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World mine production of rare earth elements (REEs) by country for 2018 (data from Gambogi, 2019). The total world production for 2018 was 170,000 metric tons (t); 1 t = 2,204 pounds. Country totals may not add exactly to the world total because of rounding. U.S. Department of the Interior U.S. Geological Survey Fact Sheet 2019–3048 September ...
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In this study a two stage hydrometallurgical treatment of eudialyte concentrate is presented, aiming on recovering rare earth elements and suppressing silica gel formation, The proposed treatment incorporates a preprocessing step called "Fuming", which is the addition of an acidic solution to eudialyte concentrate heated at boiling …
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The geochemical behaviour of REE is influenced by nearly all important hydrothermal ore formation processes including fluid-rock interactions, fluid precipitations, adsorption and scavenging onto particles, and changes in fluid temperature, pressure, pH, Eh, alkalinity and ligand concentration. Destabilization of REE complexes …
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rare earth elements because of their close affiliation and frequent geological coincidence. Currently, scandium and yttrium are also counted as rare earths, although they are found elsewhere on the periodic table: atomic numbers 21 and 39, respectively. Therefore, at present, rare earths refers to a group of 17 chemically-similar
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Despite their name, rare earths are plentiful in Earth's crust. However, China has a near monopoly on global production: in 2017, 81% of rare earths worldwide were sourced from China.
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