Influence of the Alkali-promoted phase transformation in monazite for selective recovery of rare-oxides using deep eutectic solvents

Sergio Sanchez-Segado; Shannon Stodd; Vitalis Chipakwe; Edward Loye; Martin Smith; Frances Wall; Andrew Abbott; Animesh Jha

doi:10.1016/j.mineng.2022.107564

Influence of the Alkali-promoted phase transformation in monazite for selective recovery of rare-oxides using deep eutectic solvents

Sergio Sanchez-Segado, Shannon Stodd, Vitalis Chipakwe, Edward Loye, Martin Smith, Frances Wall, Andrew Abbott, Animesh Jha

School of Applied Sciences

Research output: Contribution to journal › Article › peer-review

Abstract

The physico-chemical changes occurring during the high-temperature phase transformation of monazite in the presence of Na2CO3 at 1000 °C for 2 h duration at monazite: Na2CO3 ratios between 1.0 and 5.0, were investigated. The formation of sodium lanthanide phosphates was prevalent above a monazite:alkali ratio of 2, however, below this ratio, the dephosphorization of monazite as Na3PO4 and Ce1-xLnxO2-x/2 solid solutions occur offering unique selectivity for rare-earth oxide separation from the mineral matrix. Cyclic voltammetry of pure CeO2, La2O3, Nd2O3, and PrO2/Pr2O3 was carried out in the deep eutectic solvent Ethaline (1:2 mixture of choline chloride and ethylene glycol) proving the electrochemical activity of these oxides. Electrodissolution of pure oxides and water-leached monazite after high-temperature reaction with a ratio of 1:1 was carried out in a 0.1 mol/L glucose solution in Ethaline showing a preferential solubility of 23.85% for pure Nd2O3. In contrast, pure oxides of CeO2, La2O3 and PrO2/Pr2O3 were found to be insoluble. We also observed that electrodissolution of the water leached monazite was not possible because of the inert behaviour of Ce1-xLnxO2-x/2 solid solutions. Avoiding cerium oxidation during the high-temperature process will lead to a method for further selectivity for rare-earth oxide processing using staged electro-chemical winning of oxides.

Original language	English
Article number	107564
Number of pages	11
Journal	Minerals Engineering
Volume	182
DOIs	https://doi.org/10.1016/j.mineng.2022.107564
Publication status	Published - 26 Apr 2022

Bibliographical note

Funding Information:
The authors acknowledge the financial support from the NERC Minerals Security of Supply, SoS RARE grants (NE/M011429/1), (NE/M011267/1), (NE/M01147X/1), Tellurium and Selenium Cycling and Supply (TeaSe) grant NE/M010848/1 and from the NERC's Catalyst Grant reference NE/L002280/1. Dr Sanchez-Segado acknowledges the support from The Ministry of Science, Innovation and University of Spain (“Beatriz Galindo” Fellowship BEAGAL18/00079).

Publisher Copyright:
© 2022 The Authors

Keywords

mineral processing
rare earth element
alkali roasting
deep eutectic solvent
monazite
electrodissolution

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title = "Influence of the Alkali-promoted phase transformation in monazite for selective recovery of rare-oxides using deep eutectic solvents",

abstract = "The physico-chemical changes occurring during the high-temperature phase transformation of monazite in the presence of Na2CO3 at 1000 °C for 2 h duration at monazite: Na2CO3 ratios between 1.0 and 5.0, were investigated. The formation of sodium lanthanide phosphates was prevalent above a monazite:alkali ratio of 2, however, below this ratio, the dephosphorization of monazite as Na3PO4 and Ce1-xLnxO2-x/2 solid solutions occur offering unique selectivity for rare-earth oxide separation from the mineral matrix. Cyclic voltammetry of pure CeO2, La2O3, Nd2O3, and PrO2/Pr2O3 was carried out in the deep eutectic solvent Ethaline (1:2 mixture of choline chloride and ethylene glycol) proving the electrochemical activity of these oxides. Electrodissolution of pure oxides and water-leached monazite after high-temperature reaction with a ratio of 1:1 was carried out in a 0.1 mol/L glucose solution in Ethaline showing a preferential solubility of 23.85% for pure Nd2O3. In contrast, pure oxides of CeO2, La2O3 and PrO2/Pr2O3 were found to be insoluble. We also observed that electrodissolution of the water leached monazite was not possible because of the inert behaviour of Ce1-xLnxO2-x/2 solid solutions. Avoiding cerium oxidation during the high-temperature process will lead to a method for further selectivity for rare-earth oxide processing using staged electro-chemical winning of oxides.",

keywords = "mineral processing, rare earth element, alkali roasting, deep eutectic solvent, monazite, electrodissolution",

author = "Sergio Sanchez-Segado and Shannon Stodd and Vitalis Chipakwe and Edward Loye and Martin Smith and Frances Wall and Andrew Abbott and Animesh Jha",

note = "Funding Information: The authors acknowledge the financial support from the NERC Minerals Security of Supply, SoS RARE grants (NE/M011429/1), (NE/M011267/1), (NE/M01147X/1), Tellurium and Selenium Cycling and Supply (TeaSe) grant NE/M010848/1 and from the NERC's Catalyst Grant reference NE/L002280/1. Dr Sanchez-Segado acknowledges the support from The Ministry of Science, Innovation and University of Spain (“Beatriz Galindo” Fellowship BEAGAL18/00079). Publisher Copyright: {\textcopyright} 2022 The Authors",

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doi = "10.1016/j.mineng.2022.107564",

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AU - Sanchez-Segado, Sergio

AU - Stodd, Shannon

AU - Chipakwe, Vitalis

AU - Loye, Edward

AU - Smith, Martin

AU - Wall, Frances

AU - Abbott, Andrew

AU - Jha, Animesh

N1 - Funding Information: The authors acknowledge the financial support from the NERC Minerals Security of Supply, SoS RARE grants (NE/M011429/1), (NE/M011267/1), (NE/M01147X/1), Tellurium and Selenium Cycling and Supply (TeaSe) grant NE/M010848/1 and from the NERC's Catalyst Grant reference NE/L002280/1. Dr Sanchez-Segado acknowledges the support from The Ministry of Science, Innovation and University of Spain (“Beatriz Galindo” Fellowship BEAGAL18/00079). Publisher Copyright: © 2022 The Authors

PY - 2022/4/26

Y1 - 2022/4/26

N2 - The physico-chemical changes occurring during the high-temperature phase transformation of monazite in the presence of Na2CO3 at 1000 °C for 2 h duration at monazite: Na2CO3 ratios between 1.0 and 5.0, were investigated. The formation of sodium lanthanide phosphates was prevalent above a monazite:alkali ratio of 2, however, below this ratio, the dephosphorization of monazite as Na3PO4 and Ce1-xLnxO2-x/2 solid solutions occur offering unique selectivity for rare-earth oxide separation from the mineral matrix. Cyclic voltammetry of pure CeO2, La2O3, Nd2O3, and PrO2/Pr2O3 was carried out in the deep eutectic solvent Ethaline (1:2 mixture of choline chloride and ethylene glycol) proving the electrochemical activity of these oxides. Electrodissolution of pure oxides and water-leached monazite after high-temperature reaction with a ratio of 1:1 was carried out in a 0.1 mol/L glucose solution in Ethaline showing a preferential solubility of 23.85% for pure Nd2O3. In contrast, pure oxides of CeO2, La2O3 and PrO2/Pr2O3 were found to be insoluble. We also observed that electrodissolution of the water leached monazite was not possible because of the inert behaviour of Ce1-xLnxO2-x/2 solid solutions. Avoiding cerium oxidation during the high-temperature process will lead to a method for further selectivity for rare-earth oxide processing using staged electro-chemical winning of oxides.

AB - The physico-chemical changes occurring during the high-temperature phase transformation of monazite in the presence of Na2CO3 at 1000 °C for 2 h duration at monazite: Na2CO3 ratios between 1.0 and 5.0, were investigated. The formation of sodium lanthanide phosphates was prevalent above a monazite:alkali ratio of 2, however, below this ratio, the dephosphorization of monazite as Na3PO4 and Ce1-xLnxO2-x/2 solid solutions occur offering unique selectivity for rare-earth oxide separation from the mineral matrix. Cyclic voltammetry of pure CeO2, La2O3, Nd2O3, and PrO2/Pr2O3 was carried out in the deep eutectic solvent Ethaline (1:2 mixture of choline chloride and ethylene glycol) proving the electrochemical activity of these oxides. Electrodissolution of pure oxides and water-leached monazite after high-temperature reaction with a ratio of 1:1 was carried out in a 0.1 mol/L glucose solution in Ethaline showing a preferential solubility of 23.85% for pure Nd2O3. In contrast, pure oxides of CeO2, La2O3 and PrO2/Pr2O3 were found to be insoluble. We also observed that electrodissolution of the water leached monazite was not possible because of the inert behaviour of Ce1-xLnxO2-x/2 solid solutions. Avoiding cerium oxidation during the high-temperature process will lead to a method for further selectivity for rare-earth oxide processing using staged electro-chemical winning of oxides.

KW - mineral processing

KW - rare earth element

KW - alkali roasting

KW - deep eutectic solvent

KW - monazite

KW - electrodissolution

U2 - 10.1016/j.mineng.2022.107564

DO - 10.1016/j.mineng.2022.107564

M3 - Article

VL - 182

M1 - 107564

ER -

Influence of the Alkali-promoted phase transformation in monazite for selective recovery of rare-oxides using deep eutectic solvents

Abstract

Bibliographical note

Keywords

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