scholarly journals Hydrometallurgical Recovery and Process Optimization of Rare Earth Fluorides from Recycled Magnets

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 340 ◽  
Author(s):  
Prince Sarfo ◽  
Thomas Frasz ◽  
Avimanyu Das ◽  
Courtney Young
Keyword(s):  
Rare Earth ◽  
Sulfuric Acid ◽  
Process Optimization ◽  
Ammonium Hydroxide ◽  
Environmental Issues ◽  
Recovery Process ◽  
Response Model ◽  
Unique Approach ◽  
Ammonium Jarosite ◽  
Rare Earth Fluorides

Magnets containing substantial quantities of rare earth elements are currently one of the most sought-after commodities because of their strategic importance. Recycling these rare earth magnets after their life span has been identified to be a unique approach for mitigating environmental issues that originate from mining and also for sustaining natural resources. The approach is hydrometallurgical, with leaching and precipitation followed by separation and recovery of neodymium (Nd), praseodymium (Pr) and dysprosium (Dy) in the form of rare earth fluorides (REF) as the final product. The methodology is specifically comprised of sulfuric acid (H2SO4) leaching and ammonium hydroxide (NH4OH) precipitation followed by reacting the filtrate with ammonium bifluoride (NH4F·HF) to yield the REF. Additional filtering also produces ammonium sulfate ((NH4)2SO4) as a byproduct fertilizer. Quantitative and qualitative evaluations by means of XRD, ICP and TGA-DSC to determine decomposition of ammonium jarosite, which is an impurity in the recovery process were performed. Additionally, conditional and response variables were used in a surface-response model to optimize REF production from end-of-life magnets. A REF recovery of 56.2% with a REF purity of 62.4% was found to be optimal.

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

scholarly journals Effective Recovery Process of Copper from Waste Printed Circuit Boards Utilizing Recycling of Leachate

JOM ◽  
2020 ◽  
Author(s):  
Joona Rajahalme ◽  
Siiri Perämäki ◽  
Roshan Budhathoki ◽  
Ari Väisänen
Keyword(s):  
Hydrogen Peroxide ◽  
Sulfuric Acid ◽  
Printed Circuit Boards ◽  
Sulfuric Acid Concentration ◽  
Recovery Process ◽  
Copper Recovery ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Acid Consumption

AbstractThis study presents an optimized leaching and electrowinning process for the recovery of copper from waste printed circuit boards including studies of chemical consumption and recirculation of leachate. Optimization of leaching was performed using response surface methodology in diluted sulfuric acid and hydrogen peroxide media. Optimum leaching conditions for copper were found by using 3.6 mol L−1 sulfuric acid, 6 vol.% hydrogen peroxide, pulp density of 75 g L−1 with 186 min leaching time at 20°C resulting in complete leaching of copper followed by over 92% recovery and purity of 99.9% in the electrowinning. Study of chemical consumption showed total decomposition of hydrogen peroxide during leaching, while changes in sulfuric acid concentration were minor. During recirculation of the leachate with up to 5 cycles, copper recovery and product purity remained at high levels while acid consumption was reduced by 60%.

High-pressure Syntheses and Characterization of the Rare-earth Fluoride Borates RE2(BO3)F3 (RE=Tb, Dy, Ho)

2013 ◽  
Vol 68 (11) ◽  
pp. 1198-1206 ◽  
Author(s):  
Ernst Hinteregger ◽  
Michael Enders ◽  
Almut Pitscheider ◽  
Klaus Wurst ◽  
Gunter Heymann ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Rare Earth ◽  
Monoclinic Space Group ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Structure Determinations ◽  
New Compounds ◽  
Rare Earth Fluorides

The new rare-earth fluoride borates RE2(BO3)F3 (RE=Tb, Dy, Ho) were synthesized under highpressure/ high-temperature conditions of 1:5 GPa=1200 °C for Tb2(BO3)F3 and 3:0 GPa=900 °C for Dy2(BO3)F3 and Ho2(BO3)F3 in a Walker-type multianvil apparatus from the corresponding rareearth sesquioxides, rare-earth fluorides, and boron oxide. The single-crystal structure determinations revealed that the new compounds are isotypic to the known rare-earth fluoride borate Gd2(BO3)F3. The new rare-earth fluoride borates crystallize in the monoclinic space group P21/c (Z = 8) with the lattice parameters a=16:296(3), b=6:197(2), c=8:338(2) Å , b =93:58(3)° for Tb2(BO3)F3, a= 16:225(3), b = 6:160(2), c = 8:307(2) Å , b = 93:64(3)° for Dy2(BO3)F3, and a = 16:189(3), b = 6:124(2), c = 8:282(2) Å , β= 93:69(3)° for Ho2(BO3)F3. The four crystallographically different rare-earth cations (CN=9) are surrounded by oxygen and fluoride anions. All boron atoms form isolated trigonal-planar [BO3]3- groups. The six crystallographically different fluoride anions are in a nearly planar coordination by three rare-earth cations.

ChemInform Abstract: The Versatility of Solid-State Metathesis Reactions: From Rare Earth Fluorides to Carbodiimides.

ChemInform ◽  
2009 ◽  
Vol 40 (20) ◽  
Author(s):  
Leonid Unverfehrt ◽  
Jochen Glaser ◽  
Markus Stroebele ◽  
Sonja Tragl ◽  
Katharina Gibson ◽  
...  
Keyword(s):  
Rare Earth ◽  
Solid State ◽  
Metathesis Reactions ◽  
Rare Earth Fluorides

Nanocrystalline rare earth fluorides doped with Pr3+ ions

2016 ◽  
Vol 34 (8) ◽  
pp. 802-807 ◽  
Author(s):  
Marcin Runowski ◽  
Stefan Lis
Keyword(s):  
Rare Earth ◽  
Rare Earth Fluorides

Process optimization for acidic leaching of rare earth elements (REE) from waste electrical and electronic equipment (WEEE)

2021 ◽  
Author(s):  
Ayse Yuksekdag ◽  
Borte Kose-Mutlu ◽  
Bihter Zeytuncu-Gokoglu ◽  
Mustafa Kumral ◽  
Mark R. Wiesner ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Process Optimization ◽  
Electronic Equipment

A Unique Approach to Characterization of Sol-Gel-Derived Rare-Earth-Doped Oxyfluoride Glass-Ceramics

2012 ◽  
Vol 96 (2) ◽  
pp. 476-480 ◽  
Author(s):  
Go Kawamura ◽  
Ryota Yoshimura ◽  
Kazunari Ota ◽  
Song-Yul Oh ◽  
Norio Hakiri ◽  
...  
Keyword(s):  
Rare Earth ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Oxyfluoride Glass ◽  
Unique Approach ◽  
Rare Earth Doped

Epitaxial Growth of Rare Earths on Rare Earth Fluorides and Rare Earth Fluorides on Rare Earths: Two New Epitaxial Systems Accessed by MBE

1987 ◽  
Vol 103 ◽  
Author(s):  
R. F. C. Farrow ◽  
S. S. P. Parkin ◽  
M. Lang ◽  
K. P. Roche
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Rare Earth Metal ◽  
Basal Plane ◽  
Earth Metal ◽  
Magnetic Ordering ◽  
Metal Films ◽  
Squid Magnetometry ◽  
New Family ◽  
Rare Earth Fluorides

ABSTRACTWe report two new epitaxial systems, prepared by MBE: basal plane epitaxy of the rare earth metal Dy onto LaF3 films and vice versa. SQUID magnetometry studies indicate that buried epitaxial Dy films, of ∼300Å thick, order ferromagnetically at similar temperatures to bulk Dy crystals.These epitaxial systems are one member of a new family of epitaxial systems of basal plane epitaxy of rare earth metals on rare earth fluorides and vice versa. Such systems may be used to probe the effects of strain and dimensionality on magnetic ordering in rare earth metal films and multilayers.

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