Rare earth elements in three fluorites: graphical comparison of data and model Comment to "Mathematical analysis of rare earth element patterns of fluorites from the Ehrenfriedersdorf tin deposit, Germany: evidence for a hydrothermal mixing process of lanthanides from two different sources" by T. Monecke et al.

2002 ◽  
Vol 75 (3-4) ◽  
pp. 243-244
Author(s):  
T. P. Hutchinson
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Mathematical Analysis ◽  
Earth Element ◽  
Mixing Process ◽  
Graphical Comparison ◽  
Tin Deposit ◽  
Different Sources

scholarly journals Rare earth element mobility in and around carbonatites controlled by sodium, potassium, and silica

2020 ◽  
Vol 6 (41) ◽  
pp. eabb6570 ◽  
Author(s):  
Michael Anenburg ◽  
John A. Mavrogenes ◽  
Corinne Frigo ◽  
Frances Wall
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Element Mobility ◽  
Sodium Potassium ◽  
Ree Mineralization ◽  
Anionic Species ◽  
Ree Mobility ◽  
Modern Technologies

Carbonatites and associated rocks are the main source of rare earth elements (REEs), metals essential to modern technologies. REE mineralization occurs in hydrothermal assemblages within or near carbonatites, suggesting aqueous transport of REE. We conducted experiments from 1200°C and 1.5 GPa to 200°C and 0.2 GPa using light (La) and heavy (Dy) REE, crystallizing fluorapatite intergrown with calcite through dolomite to ankerite. All experiments contained solutions with anions previously thought to mobilize REE (chloride, fluoride, and carbonate), but REEs were extensively soluble only when alkalis were present. Dysprosium was more soluble than lanthanum when alkali complexed. Addition of silica either traps REE in early crystallizing apatite or negates solubility increases by immobilizing alkalis in silicates. Anionic species such as halogens and carbonates are not sufficient for REE mobility. Additional complexing with alkalis is required for substantial REE transport in and around carbonatites as a precursor for economic grade-mineralization.

scholarly journals The Occurrence States of Rare Earth Elements Bearing Phosphorite Ores and Rare Earth Enrichment Through the Selective Reverse Flotation

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 698
Author(s):  
Wenxiang Chen ◽  
Feng Zhou ◽  
Hongquan Wang ◽  
Sen Zhou ◽  
Chunjie Yan
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Ion Beam ◽  
Western China ◽  
Reverse Flotation ◽  
Flotation Process ◽  
Element Bearing ◽  
Element Contents

The reserve of rare-earth element-bearing phosphorite ores in Guizhou province in western China is huge. Increased demand for the different products manufactured from rare-earth elements has resulted in an extreme need for reasonable and comprehensive extraction of rare-earth elements. An improved understanding of rare-earth element occurrence states in single minerals of ores is important for their further processing. In this paper, rare-earth element contents were analyzed by inductively coupled plasma (ICP), and the occurrence states in single minerals were further investigated through SEM-EDS and focused ion beam-scanning electron microscope (FIB-SEM) methods. The results indicate that rare-earth element contents of apatite are far more than that of dolomite. No independent mineral of rare-earth elements exists for the studied sample. Rare-earth elements are present in the form of ions in the lattices of apatite. Based on the analysis of occurrence states and properties in single minerals, the distribution of rare-earth elements in the flotation process was investigated by reverse flotation technology. It shows that rare-earth elements are mainly concentrated in apatite concentrate. Under the optimized conditions, the P2O5 grade increases from 11.36% in the raw ore to 26.04% in the concentrate, and the recovery is 81.92%, while the total rare-earth oxide grade increases from 0.09% to 0.21% with the recovery of 80.01%, which is similar to P2O5 recovery. This study presents the feasibility of extracting rare-earth elements from rare-earth element-bearing phosphorite ores through the flotation of apatite.

Study on Mechanisms of Rare Earth Elements on Improving Thermoelectric Properties of RExCo4Sb12

2011 ◽  
Vol 71-78 ◽  
pp. 3737-3740
Author(s):  
Ke Gao Liu ◽  
Jing Li
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Mechanical Alloy ◽  
Spark Plasma Sintering ◽  
Thermoelectric Properties ◽  
Rare Earth Element ◽  
Figure Of Merit ◽  
Earth Element ◽  
Plasma Sintering ◽  
Spark Plasma

It is the important way to improve thermoelectric properties of skutterudite materials by doping with rare earth elements. The mechanisms of improving properties of bulk RExCo4Sb12materials prepared by mechanical alloy and spark plasma sintering (MA-SPS) at 650°C were investigated by analyzing the composition, microstructure and atomic occupying locations. According the results it can be considered that the mechanism to improve the thermoelectric properties of rare earth elements is that rare earth element Ce in the samples mainly plays the doping role in reducing the resistivity of the sample and improving the conductivity, so that it makes the figure of merit ZT of samples increase significantly.

Fractionation of rare-earth elements during magmatic differentiation and weathering of calc-alkaline granites in southern Myanmar

2016 ◽  
Vol 80 (1) ◽  
pp. 77-102 ◽  
Author(s):  
Kenzo Sanematsu ◽  
Terumi Ejima ◽  
Yoshiaki Kon ◽  
Takayuki Manaka ◽  
Khin Zaw ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Geochemical Characteristics ◽  
Magmatic Differentiation ◽  
Calc Alkaline ◽  
Mineral Assemblages ◽  
Weathering Resistance

AbstractGeochemical characteristics and rare-earth element (REE)-bearing minerals of calc-alkaline granites in southern Myanmar were investigated to identify the minerals controlling fractionation between light and heavyREE(LREE and HREE) during magmatic differentiation and weathering. The granites were classified on the basis of the mineral assemblages into two contrasting groups: allanite-(Ce)- and/or titanite-bearing granites; and more HREE-enriched granites characterized by hydrothermal minerals including synchysite(Y), parisite-(Ce), bastnäsite-(Ce), xenotime-(Y), monazite-(Ce), Y-Ca silicate, waimirite-(Y) and fluorite. This suggests that allanite-(Ce) and titanite are not stable in differentiated magma and HREE are eventually preferentially incorporated into the hydrothermal minerals. The occurrence of theREE-bearing minerals is constrained by the degree of magmatic differentiation and the boundary of two contrasting granite groups is indicated by SiO2contents of ∼74 wt.% or Rb/Sr ratios of ∼3–8. Fractionation between LREE and HREE during weathering of the granites is influenced by weathering resistance of theREE-bearing minerals, i.e. allanite-(Ce), titanite, theREEfluorocarbonates and waimirite-(Y) are probably more susceptible to weathering, whereas zircon, monazite-(Ce) and xenotime-(Y) are resistant to weathering. Ion-exchangeableREEin weathered granites tend to be depleted in HREE relative to the whole-rock compositions, suggesting that HREE are more strongly adsorbed on weathering products or that HREE remain in residual minerals.

Study on Recovery of Rare Earth Elements from NdFeB Magnet Scrap by Using Selective Leaching

2020 ◽  
Vol 1009 ◽  
pp. 149-154
Author(s):  
Tanongsak Yingnakorn ◽  
Piamsak Laokhen ◽  
Loeslakkhana Sriklang ◽  
Tapany Patcharawit ◽  
Sakhob Khumkoa
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Rare Earth Metals ◽  
Hard Disk Drives ◽  
Selective Leaching ◽  
High Concentration ◽  
Neodymium Magnets ◽  
The Rare Earth

High power neodymium magnets have been used extensively, such as components of hard disk drives, electric vehicles, and maglev trains. This type of magnet contains of high concentration of rare earth elements. After the device is out of service, the magnet will be removed and the rare earth element contained in the magnet will be extracted in order to reuse for any purposes. Recently, the study on extraction of rare earth elements (REE) from neodymium magnets is increased. However, there was only few research regarding to the extraction of rare earth metals by using a water leaching method. In this study, rare-earth elements were extracted from neodymium magnet scrap by using selective leaching technique. Initially, magnets were leached with 2 M of sulfuric acid for 24 hrs. Then, the leached solution was heated at 110°C in order to remove water and the green powder was remained. The green powder was further roasted in a muffle furnace at various temperatures from 750°C to 900°C for 2 hrs. and subsequently leached by water. Finally, the iron oxide residue was separated from rare earth element solution by filtration. Based on this experiment, it was found that the purity of the rare earth metals can be achieved up to 99.4%.

Foliar application of rare earth elements to maize and mungbean

1999 ◽  
Vol 39 (2) ◽  
pp. 189 ◽  
Author(s):  
E. Diatloff ◽  
C. J. Asher ◽  
F. W. Smith
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Foliar Application ◽  
Dry Weight ◽  
Cerium Nitrate ◽  
Beneficial Effects ◽  
Shoot Dry Weight ◽  
The Rare Earth

The foliar application of rare earth elements to plants has been reported to increase yields of a range of crops particularly when soils contain low levels of rare earth elements. A rare earth element fertiliser obtained from China was chemically analysed and found to contain 45.3% nitrate plus 8.7% lanthanum and 12.4% cerium; lanthanum and cerium were the most abundant rare earth elements measured. This fertiliser was applied once, as 0, 0.025, 0.05, 0.1, 0.5 and 1.0% (w/v) aqueous solutions to the foliage of 10-day-old maize (Zea mays L. cv. Hycorn 82) and 14-day-old mungbean [Vigna radiata (L.) Wilczek cv. Berken] plants grown in a nutrient-rich potting mix of low total rare earth element status. For comparison, a duplicate set of plants was sprayed with solutions containing analytical grade lanthanum and cerium nitrate at concentrations equivalent to those measured in the rare earth element fertiliser. No beneficial effects of the rare earth element treatments were observed. The shoots of maize and mungbean sprayed with ≤0.1% rare earth element fertiliser or equivalent appeared completely healthy throughout the experiment, but plants in the 0.5 and 1.0% treatments showed symptoms of leaf burn in maize, and small necrotic spots on mungbean leaves within 1–3 days of treatment. These symptoms became more severe over the next 5–9 days. The shoot dry weight of mungbean sprayed with 0.5 and 1.0% solutions was significantly (P<0.05) reduced by 27%. Symptoms observed on plants sprayed with lanthanum and cerium nitrate solutions were similar to those observed on plants sprayed with the rare earth element fertiliser, and similar growth reductions occurred also.

The Application of Rare-Earth Element

2011 ◽  
Vol 233-235 ◽  
pp. 3005-3009
Author(s):  
Yu Cai Wu ◽  
Ming Yan
Keyword(s):  
Tensile Strength ◽  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Additive Process ◽  
Contact Wire ◽  
Specific Elongation ◽  
Ag Contact ◽  
The Rare Earth

In this paper, the process of Cu-Ag contact wire with adding rare-earth elements was presented. The additive process of the rare-earth elements and the function of the rare earth were chiefly analyzed. Adding the rare-earth elements into melt alloy, the oxide and sulfur can be removed from the liquid, so we can get the purified alloy. At the same time, adding rare-earth can reduce the external crack flaws which produced during the casting and makes the grain refined, as the result, the properties of the Cu-Ag alloy contact wire can be greatly improved and meliorated. Such as the conductivity, the specific elongation, tensile strength and so on, are improved.

Geochemistry of the rare-earth elements in hypersaline and dilute acidic natural terrestrial waters: Complexation behavior and middle rare-earth element enrichments

1996 ◽  
Vol 133 (1-4) ◽  
pp. 125-144 ◽  
Author(s):  
Kevin H. Johannesson ◽  
W.Berry Lyons ◽  
Mary A. Yelken ◽  
Henri E. Gaudette ◽  
Klaus J. Stetzenbach
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
The Rare Earth
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