Application of eh-ph diagrams on acid leaching systems for the recovery of rees from bastnaesite, monazite and xenotime

Peijia Lin; Xinbo Yang; Joshua M. Werner; Rick Q. Honaker

doi:10.3390/met11050734

Application of eh-ph diagrams on acid leaching systems for the recovery of rees from bastnaesite, monazite and xenotime

Peijia Lin, Xinbo Yang, Joshua M. Werner, Rick Q. Honaker

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

13 Scopus citations

Abstract

Bastnaesite, monazite and xenotime are rare earth minerals (REMs) that are typical sources for rare earth elements (REEs). To advance the understanding of their leaching and precipitation behavior in different hydrometallurgical processes, Eh-pH diagrams were constructed and modified using the HSC 9.9 software. The aqueous stability of rare earth elements in H₂ O and acid leaching systems, i.e., the REE-Ligands-H₂ O systems, were depicted and studied based on the Eh-pH diagrams. This study considers the most relevant lixiviants, their resulting equilibrium states and the importance in the hydrometallurgical recovery of rare earth elements (REMs). A literature review was performed summarizing relevant Eh-pH diagrams and associated thermodynamic data. Shifting stability regions for REEs were discovered with additions of acid ligands and a narrow stability region for soluble REE-(SO₄ /Cl/NO₃ ) complexes under highly acidic conditions. As such, the recovery of REEs can be enhanced by adjusting pH and Eh values. In addition, the Eh-pH diagrams of the major contaminants (i.e., Fe, Ca and Al) in leaching systems were studied. The resulting Eh-pH diagrams provide possible insights into potential passivation on the particle surfaces due to the formation of an insoluble product layer.

Original language	English
Article number	734
Journal	Metals
Volume	11
Issue number	5
DOIs	https://doi.org/10.3390/met11050734
State	Published - May 2021

Bibliographical note

Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Funding

This research was funded by the Department of Energy of United States (DOE-FE0029900), project titled ?Recovery of Rare Earth Elements from Coal Byproducts: Characterization and Laboratory-Scale Separation Tests?. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process or service by trade name, trademark, manufacturer or otherwise does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

Funders	Funder number
United States Government

Keywords

Eh-pH diagrams
Leaching
Rare earth elements
Rare earth minerals
Solution stability

ASJC Scopus subject areas

General Materials Science
Metals and Alloys

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10.3390/met11050734

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title = "Application of eh-ph diagrams on acid leaching systems for the recovery of rees from bastnaesite, monazite and xenotime",

abstract = "Bastnaesite, monazite and xenotime are rare earth minerals (REMs) that are typical sources for rare earth elements (REEs). To advance the understanding of their leaching and precipitation behavior in different hydrometallurgical processes, Eh-pH diagrams were constructed and modified using the HSC 9.9 software. The aqueous stability of rare earth elements in H2 O and acid leaching systems, i.e., the REE-Ligands-H2 O systems, were depicted and studied based on the Eh-pH diagrams. This study considers the most relevant lixiviants, their resulting equilibrium states and the importance in the hydrometallurgical recovery of rare earth elements (REMs). A literature review was performed summarizing relevant Eh-pH diagrams and associated thermodynamic data. Shifting stability regions for REEs were discovered with additions of acid ligands and a narrow stability region for soluble REE-(SO4 /Cl/NO3 ) complexes under highly acidic conditions. As such, the recovery of REEs can be enhanced by adjusting pH and Eh values. In addition, the Eh-pH diagrams of the major contaminants (i.e., Fe, Ca and Al) in leaching systems were studied. The resulting Eh-pH diagrams provide possible insights into potential passivation on the particle surfaces due to the formation of an insoluble product layer.",

keywords = "Eh-pH diagrams, Leaching, Rare earth elements, Rare earth minerals, Solution stability",

author = "Peijia Lin and Xinbo Yang and Werner, {Joshua M.} and Honaker, {Rick Q.}",

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language = "English",

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AU - Yang, Xinbo

AU - Werner, Joshua M.

AU - Honaker, Rick Q.

PY - 2021/5

Y1 - 2021/5

N2 - Bastnaesite, monazite and xenotime are rare earth minerals (REMs) that are typical sources for rare earth elements (REEs). To advance the understanding of their leaching and precipitation behavior in different hydrometallurgical processes, Eh-pH diagrams were constructed and modified using the HSC 9.9 software. The aqueous stability of rare earth elements in H2 O and acid leaching systems, i.e., the REE-Ligands-H2 O systems, were depicted and studied based on the Eh-pH diagrams. This study considers the most relevant lixiviants, their resulting equilibrium states and the importance in the hydrometallurgical recovery of rare earth elements (REMs). A literature review was performed summarizing relevant Eh-pH diagrams and associated thermodynamic data. Shifting stability regions for REEs were discovered with additions of acid ligands and a narrow stability region for soluble REE-(SO4 /Cl/NO3 ) complexes under highly acidic conditions. As such, the recovery of REEs can be enhanced by adjusting pH and Eh values. In addition, the Eh-pH diagrams of the major contaminants (i.e., Fe, Ca and Al) in leaching systems were studied. The resulting Eh-pH diagrams provide possible insights into potential passivation on the particle surfaces due to the formation of an insoluble product layer.

AB - Bastnaesite, monazite and xenotime are rare earth minerals (REMs) that are typical sources for rare earth elements (REEs). To advance the understanding of their leaching and precipitation behavior in different hydrometallurgical processes, Eh-pH diagrams were constructed and modified using the HSC 9.9 software. The aqueous stability of rare earth elements in H2 O and acid leaching systems, i.e., the REE-Ligands-H2 O systems, were depicted and studied based on the Eh-pH diagrams. This study considers the most relevant lixiviants, their resulting equilibrium states and the importance in the hydrometallurgical recovery of rare earth elements (REMs). A literature review was performed summarizing relevant Eh-pH diagrams and associated thermodynamic data. Shifting stability regions for REEs were discovered with additions of acid ligands and a narrow stability region for soluble REE-(SO4 /Cl/NO3 ) complexes under highly acidic conditions. As such, the recovery of REEs can be enhanced by adjusting pH and Eh values. In addition, the Eh-pH diagrams of the major contaminants (i.e., Fe, Ca and Al) in leaching systems were studied. The resulting Eh-pH diagrams provide possible insights into potential passivation on the particle surfaces due to the formation of an insoluble product layer.

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KW - Solution stability

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Application of eh-ph diagrams on acid leaching systems for the recovery of rees from bastnaesite, monazite and xenotime

Abstract

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