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At least 793 records · Page 44Linked to original sources
USGS2015

Size distribution of rare earth elements in coal ash

Rare earth elements (REEs) are utilized in various applications that are vital to the automotive, petrochemical, medical, and information technology industries. As world demand for REEs increases, critical shortages are expected. Due to the retention of REEs during coal combustion, coal fly ash is increasingly considered a potential resource. Previous studies have demonstrated that coal fly ash is variably enriched in REEs relative to feed coal (e.g, Seredin and Dai, 2012) and that enrichment increases with decreasing size fractions (Blissett et al., 2014). In order to further explore the REE resource potential of coal ash, and determine the partitioning behavior of REE as a function of grain size, we studied whole coal and fly ash size-fractions collected from three U.S commercial-scale coal-fired generating stations burning Appalachian or Powder River Basin coal. Whole fly ash was separated into , 5 um, to 5 to 10 um and 10 to 100 um particle size fractions by mechanical shaking using trace-metal clean procedures. In these samples REE enrichments in whole fly ash ranges 5.6 to 18.5 times that of feedcoals. Partitioning results for size separates relative to whole coal and whole fly ash will also be reported.

Conference Paper↗
USGS1977

A Galerkin, finite-element analysis of steady-state flow and heat transport in the shallow hydrothermal system in the East Mesa area, Imperial Valley, California

A steady-state simulation model was applied to the shallow hydrothermal system in the East Mesa area of Imperial Valley, Calif. The steady-state equations of flow and heat transport were solved by use of a Galerkin, finite-element method. A solution was obtained by iterating between the temperature and pressure equations, using updated densities and viscosities. Temperature and pressure were obtained for each node, and corresponding head values were calculated. The simulated temperature and pressure patterns correlated well with the observed patterns. Additional data, mainly from test drilling, would be required for construction of a similar model of the deep hydrothermal system.

California↗
USGS2012

Annual fluxes of sediment-associated trace/major elements, carbon, nutrients, and sulfur from US coastal rivers

About 260–270 Mt of suspended sediment are discharged annually from the conterminous USA; approximately 69% derives from Gulf rivers (n = 36), 24% from Pacific rivers (n = 42), and 7% from Atlantic rivers (n = 54). Elevated sediment-associated chemical concentrations relative to baseline levels occur in the reverse order of sediment discharges: Atlantic rivers (49%) > Pacific rivers (40%) > Gulf rivers (23%). Elevated trace element concentrations (e.g. Cu, Zn) tend to occur in association with present/former industrial areas and/or urban centres, particularly along the northeast Atlantic coast. Elevated nutrient concentrations occur along both the Atlantic and Gulf coasts, but are dominated by rivers in the urban northeast and by southeastern and Gulf coast “blackwater” streams. Elevated Ca, Mg, K and Na levels appear to reflect local petrology whereas elevated Ti, S, Fe, and Al concentrations are ubiquitous, possibly because they have both natural and anthropogenic sources. Almost all the elevated sediment-associated chemical concentrations/fluxes are lower than worldwide averages.

United States coastal rivers↗
USGS2014

Lateritic, supergene rare earth element (REE) deposits

Intensive lateritic weathering of bedrock under tropical or sub-tropical climatic conditions can form a variety of secondary, supergene-type deposits. These secondary deposits may range in composition from aluminous bauxites to iron and niobium, and include rare earth elements (REE). Over 250 lateritic deposits of REE are currently known and many have been important sources of REE. In southeastern China, lateritic REE deposits, known as ion-adsorption type deposits, have been the world’s largest source of heavy REE (HREE). The lateritized upper parts of carbonatite intrusions are being investigated for REE in South America, Africa, Asia and Australia, with the Mt. Weld deposit in Australia being brought into production in late 2012. Lateritic REE deposits may be derived from a wide range of primary host rocks, but all have similar laterite and enrichment profiles, and are probably formed under similar climatic conditions. The weathering profile commonly consists of a depleted zone, an enriched zone, and a partially weathered zone which overlie the protolith. Lateritic weathering may commonly extend to depths of 30 to 60 m. REE are mobilized from the breakdown of primary REE-bearing minerals and redeposited in the enriched zone deeper in the weathering horizon as secondary minerals, as colloids, or adsorbed on other secondary minerals. Enrichment of REE may range from 3 to 10 times that of the source lithology; in some instances, enrichment may range up to 100 times.

Conference Paper↗
USGS2016

Documenting the use of the Long Term Resource Monitoring element’s fish monitoring methodologies throughout the Midwest

The Upper Mississippi River Restoration (UMRR) Program’s Long Term Resource Monitoring (LTRM) element is designed to monitor and assess long term trends in the Upper Mississippi River System (UMRS). To accomplish this, standardized methods are used that allow for comparisons across pools and rivers. In recent years, other projects and other agencies have adopted the LTRM fish methodologies for use outside the UMRR. To determine how widespread the use of the Fish Component’s methods are, a twelve question survey was delivered via SurveyMonkey.com through the states comprising the American Fisheries Society (AFS) North Central Division and the Upper Mississippi River Conservation Committee. Approximately 2,000 professionals were reached with ≈11 percent participating. Results indicate that nearly all (95 percent) respondents use standardized methods in their sampling and 48 percent are familiar with the LTRM fish methodologies. Roughly one-third (35 percent) of all respondents have used the methods in the past and most (78 percent) of those have modified the methods to suit the information needs specific to their fishery. Results indicate that the LTRM methods have indeed spread outside the UMRR and are now a well-known and potentially widely used technique to sample fish communities.

Illinois, Iowa, Minnesota, Missouri, Wisconsin↗
USGS1998

Transmission of atmospherically deposited trace elements through an undeveloped, forested Maryland watershed

Retention and transmission of atmospherically-derived major (H + , Na + , K + , Ca 2+ , Mg 2+ , HCO 3 - , NO 3 - , SO 4 -2 , Cl - , SiO 2 ) and trace (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Se, and Zn) species were evaluated in an undeveloped forested watershed underlain by a rather inert quartzite lithology (Bear Branch, Catoctin State Forest, Thrumont, Maryland). These comparisons were based on atmospheric input to stream export over a period of 16 months. Both wet (precipitation) and total (bulk, including vegetative throughfall) atmospheric loading to the catchment were determined. Stream export was gauged based on systematic sampling of the stream under varied flow regimes. Additionally, watershed export of both dissolved and particulate trace element phases was examined during three high run-off intensives associated with summer storms.

Maryland↗
USGS2013

Protocol for analysis of volcanic ash samples for assessment of hazards from leachable elements

Volcanic eruptions can produce a wide range of hazards. Although phenomena such as pyroclastic density currents and surges, sector collapses, lahars and ballistic blocks are the most destructive and dangerous, volcanic ash is by far the most widely distributed eruption product1 and the most likely to be encountered by the public. Following an eruption, the public, civil authorities and agricultural producers will often have major concerns about the effects of volcanic ash on human and animal health, drinking water supplies, crops, soils and surface runoff. Freshly‐erupted ash contains a range of potentially toxic soluble elements, which may be released either rapidly or more slowly upon contact with water or body fluids.

Report↗
USGS2016

Rare earth element deposits in China

China is the world’s leading rare earth element (REE) producer and hosts a variety of deposit types. Carbonatite- related REE deposits, the most significant deposit type, include two giant deposits presently being mined in China, Bayan Obo and Maoniuping, the first and third largest deposits of this type in the world, respectively. The carbonatite-related deposits host the majority of China’s REE resource and are the primary supplier of the world’s light REE. The REE-bearing clay deposits, or ion adsorption-type deposits, are second in importance and are the main source in China for heavy REE resources. Other REE resources include those within monazite or xenotime placers, beach placers, alkaline granites, pegmatites, and hydrothermal veins, as well as some additional deposit types in which REE are recovered as by-products. Carbonatite-related REE deposits in China occur along craton margins, both in rifts (e.g., Bayan Obo) and in reactivated transpressional margins (e.g., Maoniuping). They comprise those along the northern, eastern, and southern margins of the North China block, and along the western margin of the Yangtze block. Major structural features along the craton margins provide first-order controls for REE-related Proterozoic to Cenozoic carbonatite alkaline complexes; these are emplaced in continental margin rifts or strike-slip faults. The ion adsorption-type REE deposits, mainly situated in the South China block, are genetically linked to the weathering of granite and, less commonly, volcanic rocks and lamprophyres. Indosinian (early Mesozoic) and Yanshanian (late Mesozoic) granites are the most important parent rocks for these REE deposits, although Caledonian (early Paleozoic) granites are also of local importance. The primary REE enrichment is hosted in various mineral phases in the igneous rocks and, during the weathering process, the REE are released and adsorbed by clay minerals in the weathering profile. Currently, these REE-rich clays are primarily mined from open-pit operations in southern China. The complex geologic evolution of China’s Precambrian blocks, particularly the long-term subduction of ocean crust below the North and South China blocks, enabled recycling of REE-rich pelagic sediments into mantle lithosphere. This resulted in the REE-enriched nature of the mantle below the Precambrian cratons, which were reactivated and thus essentially decratonized during various tectonic episodes throughout the Proterozoic and Phanerozoic. Deep fault zones within and along the edges of the blocks, including continental rifts and strike-slip faults, provided pathways for upwelling of mantle material.

Book chapter↗
USGS2015

Late Jurassic – early Cretaceous inversion of rift structures, and linkage of petroleum system elements across post-rift unconformity, U.S. Chukchi Shelf, arctic Alaska

Basin evolution of the U.S. Chukchi shelf involved multiple phases, including Late Devonian–Permian rifting, Permian–Early Jurassic sagging, Late Jurassic–Neocomian inversion, and Cretaceous–Cenozoic foreland-basin development. The focus of ongoing exploration is a petroleum system that includes sag-phase source rocks; inversion-phase reservoir rocks; structure spanning the rift, sag, and inversion phases; and hydrocarbon generation during the foreland-basin phase. Interpretation of 2-D seismic and sparse well data documents the presence, in the south-central part of the shelf, of a series of en-echelon, north-south trending monoclonal fold limbs that display up to 1+ km (3,300 ft) of structural relief. These folds, which are located above the tips of rift-phase normal faults, are interpreted as inversion structures formed by maximum compressive stress oriented obliquely to the strike of rift-phase normal faults. Erosional relief on a Jurassic unconformity, growth strata in the overlying Upper Jurassic to Neocomian strata, and east-dipping clinoforms in a high accommodation depocenter east of the inversion structures indicate profound structural influence on sedimentation. Oil-prone source rocks, reservoir-quality sandstone, migration pathways, and structural closure are linked intimately across the Jurassic unconformity, which reflects inversion. Thus, all these key petroleum systems elements were in place when Triassic source rocks entered the oil generation window during Cretaceous–Cenozoic stratigraphic burial.

Conference Paper↗
USGS1977

Determination of 22 minor and trace elements in 8 new USGS standard rocks by instrumental activation analysis with epithermal neutrons

Epithermal neutron-activation analyses results of the 8 new USGS standard rocks are compared with results by spectrographic, X-ray fluorimetric, atomic absorption, radiochemical neutron-activation, instrumental neutron-activation (thermal neutrons), isotope-dilution mass spectrometric, spectrofluorimetric, radioisotopic dilution and delayed-neutron techniques for 22 elements. Results indicate the technique to be useful and dependable especially for Ni, Se, Rb, Sr, Mo, Ba, Tm, Ta, Th and U.

Journal of Research of the U.S. Geological Survey↗
USGS2022

PHREEQ-N-AMDTreat+REYs water-quality modeling tools to evaluate acid mine drainage treatment strategies for recovery of rare-earth elements

The PHREEQ-N-AMDTreat+REYs water-quality modeling tools have the fundamental capability to simulate aqueous chemical reactions and predict the formation of metal-rich solids during the treatment of acid mine drainage (AMD). These new user-friendly, publicly available tools were expanded from the PHREEQ-N-AMDTreat tools to include the precipitation of rare-earth elements plus yttrium (REYs) and the adsorption of REYs onto hydrous Fe, Al, and Mn oxides. The tool set consists of a caustic titration model that indicates equilibrium surface and aqueous speciation of REYs as functions of pH and caustic agent, and a kinetics+adsorption model that simulates progressive changes in pH, major ions, and REYs in water and solids during sequential steps through passive and/or active treatment. Each model has a user interface (UI) that facilitates the input of water-quality data and adjustment to geochemical or treatment system variables; for example, retention time and aeration rate are adjustable parameters in the kinetics model. On-screen graphs display results of changes in metals and associated solute concentrations as functions of pH or retention time; details are summarized in output tables. A goal of such modeling is to identify strategies that could produce a concentrated REYs extract from AMD or mine waste leachate. For example, if REYs could be concentrated after first removing substantial Fe and Al, the final REYs-bearing phase(s) could be more efficiently processed for REYs recovery and, therefore, may represent a more valuable commodity. Preliminary modeling supports the hypothesis that Fe and Al can be removed at pH < 5.5 using conventional sequential oxidation and neutralization treatment processes without removing REYs, and that further increasing pH can promote the adsorption of REYs by hydrous Mn oxides. Alternatively, chemicals such as oxalate or phosphate may be added to precipitate REYs compounds following initial steps to decrease Fe and Al concentrations. The aqueous geochemical model framework is comprehensive and permits evaluation of effects from interactive chemical and physical variables. Field studies that demonstrate REYs attenuation from AMD and corresponding solid-phase formation during specific treatment steps plus laboratory studies of aqueous/solid interactions are helpful to corroborate, refine, and constrain modelin parameters.

Conference Paper↗
USGS2023

The Mount Weld rare earth element deposit, Western Australia: A carbonatite-derived laterite

Carbonatite-hosted rare earth element (REE) deposits are the primary source of the world’s light REEs and have the potential to be a source of heavy REEs. The Mount Weld REE deposit in Western Australia is hosted in a lateritic sequence that reflects supergene enrichment of the underlying carbonatite complex. Similar to other carbonatite-related ore deposits, ore from Mount Weld displays extreme light REE (LREE) enrichment (La up to 4 wt. %), but in contrast also contains substantially higher concentrations of heavy REEs (HREEs). REE enrichment in the laterite is controlled by the breakdown of primary minerals, the release and transport of REEs, and the formation of secondary minerals. Secondary REE-bearing phosphate minerals are the primary REE-host phases in the laterite ore with monazite as the dominant phase; other REE-bearing phases include rhabdophane, cerianite, churchite, florencite, and crandallite subgroup minerals. Profiles through the laterite show that in the REE-rich zone, apatite and primary calcite have broken down, and dolomite decreases by approximately 60-100%, such that the loss of Ca and Mg, as well as Si and K, leads to a relative increase in the REEs. Sequestering of REEs in secondary mineral phases formed by groundwater further enhances the REE concentration.

Mount Weld mine↗
USGS2023

Rare earth element sources, end-use demand trends, and hydrometallurgical separations

Rare earth elements are increasing in demand due to the movement towards electrification. In particular, there is a growing need for high performance rare earth permanent magnets for motors and generators used to convert electrical energy to mechanical energy, and vice versa. Current trends in rare earth demand are reviewed and discussed as the specific rare earth metal demand can influence the choice of feed material and process selection. Australia has the potential to increase the supply of these metals. Rare earth sources in Australia are briefly reviewed, with some discussion on the Mary Kathleen Uranium Tailings opportunity. Much of the cost of recovering rare earths is in the challenging chemical separations, some examples are provided using equilibrium chemical thermodynamic diagrams to explain the specific leaching and precipitation reactions.

Conference Paper↗
USGS2025

Ages and trace element fertility of porphyry-related mineralization in the Philipsburg polymetallic district, Montana, with a comparison to Butte

The Philipsburg mining district is a Mo-Cu porphyry system with associated Cordilleran polymetallic veins. Geochronology was employed to date the porphyry (~66 Ma, U/Pb in zircon) and molybdenite mineralization from the veins (~76 Ma, Re-Os). Age results suggest that the two-mineralization events model proposed by Lund et al. (2018) for the Butte district can be applied to the Philipsburg deposit. Furthermore, common fertility indicators from zircon trace elements were analyzed with variable success to characterize the existing Mo-Cu mineralization of the Philipsburg porphyry. This raises concerns about the benefits of this method and/or the importance of sampling, which could impact exploration for similar porphyry deposits.

Montana↗
USGS2025

Formation of the Mount Weld rare earth element deposit, Western Australia: A carbonatite-derived laterite

Carbonatite-hosted rare earth element (REE) deposits are the primary source of the world’s light REEs. The Mount Weld REE deposit in Western Australia is hosted in a lateritic sequence that reflects supergene enrichment of the underlying carbonatite. Water-rock interaction is a key to the formation of this world-class deposit. REE enrichment in the laterite is controlled by the breakdown of primary minerals, the release and transport of REEs, and the formation of secondary minerals. Secondary REE-bearing phosphate minerals are the primary REE-host phases in the laterite ore with monazite as the dominant phase; other REE-bearing phases include rhabdophane, cerianite, churchite, florencite, and crandallite subgroup minerals. Profiles through the laterite show that in the REE-rich zone, apatite and primary calcite and dolomite have broken down such that the loss of Ca and Mg, as well as Si and K, leads to a relative increase in the REEs. Sequestering of REEs in secondary mineral phases formed by groundwater further enhances the REE concentration.

Mount Weld Mine↗
USGS2004

Mammalian sensitivity to elemental gold (Au?)

There is increasing documentation of allergic contact dermatitis and other effects from gold jewelry, gold dental restorations, and gold implants. These effects were especially pronounced among females wearing body-piercing gold objects. One estimate of the prevalence of gold allergy worldwide is 13%, as judged by patch tests with monovalent organogold salts. Eczema of the head and neck was the most common response of individuals hypersensitive to gold, and sensitivity can last for at least several years. Ingestion of beverages containing flake gold can result in allergic-type reactions similar to those seen in gold-allergic individuals exposed to gold through dermal contact and other routes. Studies with small laboratory mammals and injected doses of colloidal gold showed increased body temperatures, accumulations in reticular cells, and dose enhancement in tumor therapy; gold implants were associated with tissue injuries. It is proposed that Au? toxicity to mammals is associated, in part, with formation of the more reactive Au+ and Au3+ species.

Biological Trace Element Research↗