Rare earths: A review of the landscape

Ganguli, Rajive; Cook, Douglas R.

doi:10.1557/mre.2018.7

Cited by 105 publications

(82 citation statements)

References 48 publications

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“…Dichos colores son el resultado de la transición de un electrón entre diferentes orbitales f existentes (transición f-f). Esa diferencia es tan pequeña que basta la energía UV para excitarlos y generar luminiscencia por su efecto, lo que se aprovecha en el billete de 50 euros, al cual se añade una sal de europio que le da su florescencia característica cuando se observa bajo este tipo de luz (Ganguli & Cook, 2018).…”

Section: ¿Por Qué Son Magnéticos Y Luminiscentes Los Elementos De Lasunclassified

Los lantánidos: ni tierras ni raras

Parra

2019

Rev. Acad. Colomb. Cienc. Ex. Fis. Nat.

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ResumenLa tabla periódica de los elementos contiene la base fundamental del conocimiento pasado, presente y futuro de la Química. Sin embargo, aún se proponen modelos adicionales y complementarios para tratar de satisfacer todas y cada una de las propiedades físicas y químicas, en especial de aquellos elementos que actualmente no se ajustan a ella. Algunas de esas desviaciones seguramente tendrán explicaciones por aproximaciones cuánticas, obviamente desconocidas en el tiempo de la propuesta original. Específicamente, existen dos situaciones relevantes clásicas, relacionadas con las tierras raras y los actínidos, que involucran unos 30 elementos. Estos se muestran como anexos por fuera del orden previsto y, por sus características de grupos, se organizan como períodos. A pesar de los debates en torno a la reubicación de dichos elementos, que realmente no es un mero ejercicio académico, las tierras raras son valiosos materiales con múltiples aplicaciones en la vida diaria y, además, tienen un papel fundamental en el equilibrio económico y político mundial. En este artículo se presentan varios aspectos relacionados con su posición en la tabla periódica, así como las propiedades estructurales y electrónicas de sus favorables y anómalos comportamientos, sus aplicaciones y el contexto internacional por la hegemonía mundial basada en el uso de sus elementos. AbstractThe periodic table of elements contains the fundamental basis of past, present, and future knowledge of Chemistry. However, additional and complementary models are still proposed to try to satisfy the unique physical and chemical properties of those that do not conform to it. Some of these questions will surely have explanations based on quantum approaches, obviously unknown in the time of the original proposal. In the periodic table, there are two typical relevant situations related to rare lands and actinides, involving about 30 elements. These are displayed as annexes outside the intended order and having group characteristics, they are organized as periods. Despite discussions regarding the relocation of these elements, which is not an irrelevant academic exercise, rare earths are now valuable materials with multiple applications and they have a fundamental role in economic balance and global politics. This article presents several aspects related to their position in the periodic table, as well as the structural and electronic properties of their favorable and unusual behaviors, their applications, and the international context for global hegemony founded on this type of elements.

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Section: ¿Por Qué Son Magnéticos Y Luminiscentes Los Elementos De Lasunclassified

Los lantánidos: ni tierras ni raras

Parra

2019

Rev. Acad. Colomb. Cienc. Ex. Fis. Nat.

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“…Despite the many disadvantages, these wastes contain important amounts of different elements with high commercial value [5,6]. Among these, the rare earth elements (REE) [7] are considered critical raw materials [8], due to the di culty of their separation, acquisition and the uncertainty of their disposition [9]. Recent studies have shown the quantities of REE in LCD screens are economically attractive for recovery, however, the proposed methods have focused mainly on the backlight or light-emitting diodes of the LCD screens [10,11].…”

Section: Introductionmentioning

confidence: 99%

Facile method for the selective recovery of Gd and Pr from LCD screen wastes using ultrasound-assisted leaching

Toache-Pérez

Bolarín-Miró

Jesús

et al. 2020

Preprint

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Rare earth elements (REE) are essential for the production of technological devices. However, their high demand and low availability, together with an increase in electronic waste generation, compel the development of efficient, economic and green methods for recovering these elements from electronic waste. In this work, a facile method for selective recovering of REE from Liquid Crystal Display (LCD) screen wastes, employing ultrasound assisted leaching is presented. The screen wastes were milled and sieved to pass through a -325 mesh sieve (44 µm). The milled powder was subjected to ultrasound-assisted leaching in an aqueous medium, at room temperature (25 °C) and pH 6 for 60 min. Subsequently, a magnetic separation was applied to the leach residue. Inductively coupled plasma was employed to quantitatively analyze the composition of the LCD powders and determine the effectiveness of the extraction process. Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy allowed qualitative chemical analysis of the solid materials. The results show that the LCD screen wastes are formed, mainly, by amorphous oxides of Si, Fe, In, Sn and REE. The amount of Gadolinium (Gd) and Praseodymium (Pr) in the wastes were 93 and 24 mg kg-1, respectively, which justifies their recovery. X-ray diffraction analysis of the magnetic portion of the leached residue, confirmed the presence of an amorphous phase together with crystalline metallic iron alloy. The magnetic behavior, obtained by Vibration Sample Magnetometry, helped to understand the nature of the residues. The formation of this metallic alloy is attributed to the effect of high power ultrasonic during the leach. It was confirmed that the magnetic residue concentrates and recovers 87 wt% of Gd and 85 wt% of Pr contained in the original material. Therefore, ultrasound-assisted leaching is a selective and facile method for recovering Gd and Pr from waste LCD.

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“…Among these, the REE [7] are considered critical raw materials [8], due to the difficulty of their separation, acquisition and the uncertainty of their disposition [9]. Recent studies have shown the quantities of REE (yttrium, europium, cerium, principally) in LCD screens are economically attractive for recovery it, however, the proposed methods have focused mainly on the backlight or LED´s of the LCD screens [10,11].…”

Section: Introductionmentioning

confidence: 99%

Facile method for the selective recover of Gd and Pr from LCD screen wastes using ultrasound-assisted leaching

Toache-Pérez

Bolarín-Miró

Jesús

et al. 2020

Preprint

View full text Add to dashboard Cite

Rare earth elements (REE) are essential for the production of technological devices. However, their high demand and low availability, together with an increase in electronic waste generation, compel the development of efficient, economic and green methods for recovering these elements from electronic waste. In this work, a facile method for selective recovering of REE from Liquid Crystal Display (LCD) screen wastes, employing ultrasound assisted leaching is presented. The screen wastes were milled and sieved to pass through − 325 mesh sieve. The milled powder was summited to ultrasound-assisted leaching in aqueous medium, at room temperature (25 °C) and pH 6 for 60 minutes. Subsequently, a magnetic separation was applied into the leach residue. ICP was employed to quantitatively analyze the composition of the LCD powders and the effectiveness of the extraction process. SEM-EDS allowed qualitatively analyzing the chemical composition of the solid materials. The results shown that the LCD screen wastes are formed, mainly, by amorphous oxides of Si, Fe, In, Sn and REE. The amount of Gd and Pr in the wastes were 93 mg/kg and 24 mg/kg, respectively; It represents enough reason to recover it. X-ray diffraction analysis of the magnetic portion of the leaching residue, confirmed the presence of an amorphous phase together with crystalline metallic iron alloy. The magnetic behavior, obtained by Vibration Sample Magnetometry, helped to understand the nature of the residues. The formation of this metallic alloy is attributed to the effect of high power ultrasonic during the leaching. It was confirmed that the magnetic residues concentrates and recovers 87 wt. % of Gd and 85 wt. % of Pr of the total content of these REE in the magnetic residue. Therefore, ultrasound-assisted leaching is a selective and facile method for recovering Gd and Pr from a screen wastes.

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Rare earths: A review of the landscape

Abstract: ABSTRACT

Cited by 105 publications

References 48 publications

Los lantánidos: ni tierras ni raras

Los lantánidos: ni tierras ni raras

Facile method for the selective recovery of Gd and Pr from LCD screen wastes using ultrasound-assisted leaching

Facile method for the selective recover of Gd and Pr from LCD screen wastes using ultrasound-assisted leaching

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