An advanced analytical assessment of rare earth element concentration, distribution, speciation, crystallography and solid-state chemistry in fly ash

Ilemona C Okeme; Peter George  Martin; Christopher P Jones; Richard A. Crane; Theophilus Ile Ojonimi; Konstantin Ignatyev; Thomas Bligh Scott

doi:10.1016/j.sab.2020.105950

An advanced analytical assessment of rare earth element concentration, distribution, speciation, crystallography and solid-state chemistry in fly ash

Ilemona C Okeme^*, Peter George Martin, Christopher P Jones, Richard A. Crane, Theophilus Ile Ojonimi, Konstantin Ignatyev, Thomas Bligh Scott

^*Corresponding author for this work

Research output: Contribution to journal › Article (Academic Journal) › peer-review

16 Citations (Scopus)

163 Downloads (Pure)

Abstract

Fly ash represents a promising alternative source of rare earth elements (REE). However, information on REE containing mineral phases and their association with other fly ash components, vital for REE recovery from fly ash, is currently lacking. Herein, the mass fraction, distribution, crystallography and solid-state chemistry of REE, U and Th in Nigerian simulated fly ash samples were characterised using a range of laboratory and synchrotron x-ray based analytical techniques to underpin future extraction methodologies. Inductively coupled plasma mass spectrometry following full-acid digest of forty-five samples revealed recoverable average total REE content which ranged between 442 mgkg-1and 625 mgkg-1, comprising over 30wt% of the critical REE Nd, Eu, Tb, Dy, Y and Er. These REE within the fly ash samples were found to be most frequently associated with discrete monazite, xenotime and Y-bearing zircon mineral particles, with the former the most detected, which could be beneficiated through gravity separation. Analysis of monazite particles isolated from the composite samples through a complimentary suite of analytical synchrotron radiation techniques revealed a core-shell pattern, with the shell rich in colocalised Ce, Nd and La, and the core enrich in both U and Th. Ce in monazite was found to exist in a mixed trivalent and tetravalent oxidation state, with the monazite structure amorphized due to the high temperature combustion process. Such results demonstrate the strong co-association and physical distribution of REE, U and Th within monazite in fly ash; knowledge of which can subsequently be used to optimise or develop a more selective, cost-effective and environmentally friendly solvent extraction methodology, by targeting the strongly colocalised and surface bound REE in fly ash monazite particles.

Original language	English
Article number	105950
Number of pages	11
Journal	Spectrochimica Acta Part B: Atomic Spectroscopy
Volume	177
Early online date	12 Aug 2020
DOIs	https://doi.org/10.1016/j.sab.2020.105950
Publication status	Published - 1 Mar 2021

Bibliographical note

Funding Information:
The authors wish to thank Diamond Light Source for rapid access to beamline I18 (SP22876) that contributed to the results presented here. We would like to thank Sharon Uren (Senior Analytical Technician, Camborne School of Mines, University of Exeter) for performing the total acid digestion followed by ICP-MS analysis. We also wish to thank the Commonwealth Scholarship Commission for funding the PhD studentship. The SEM used in this work to conduct imaging and EDS analysis was purchased following funding by the Engineering and Physical Sciences Research Council (EPSRC), (Reference: EP/K040340/1).

Funding Information:
The authors wish to thank Diamond Light Source for rapid access to beamline I18 (SP22876) that contributed to the results presented here. We would like to thank Sharon Uren (Senior Analytical Technician, Camborne School of Mines, University of Exeter) for performing the total acid digestion followed by ICP-MS analysis. We also wish to thank the Commonwealth Scholarship Commission for funding the PhD studentship.

Funding Information:
The SEM used in this work to conduct imaging and EDS analysis was purchased following funding by the Engineering and Physical Sciences Research Council (EPSRC) , (Reference: EP/K040340/1 ).

Publisher Copyright:
© 2020 Elsevier B.V.

Keywords

Nigeria
fly ash
rare earth elements
monazite
synchrotron radiation

Access to Document

10.1016/j.sab.2020.105950

Full-text PDF (author’s accepted manuscript)
This is the author accepted manuscript (AAM). The final published version (version of record) is available online via Elsevier at https://www.sciencedirect.com/science/article/pii/S058485472030389X . Please refer to any applicable terms of use of the publisher.
Accepted author manuscript, 1.34 MBLicence: CC BY-NC-ND
Supplementary information PDFAccepted author manuscript, 557 KBLicence: CC BY-NC-ND

Handle.net

Persistent link

Cite this

Okeme, I. C., Martin, P. G., Jones, C. P., Crane, R. A., Ojonimi, T. I., Ignatyev, K., & Scott , T. B. (2021). An advanced analytical assessment of rare earth element concentration, distribution, speciation, crystallography and solid-state chemistry in fly ash. Spectrochimica Acta Part B: Atomic Spectroscopy, 177, Article 105950. https://doi.org/10.1016/j.sab.2020.105950

@article{443dabf450c6449f94c08be29617f3c2,

title = "An advanced analytical assessment of rare earth element concentration, distribution, speciation, crystallography and solid-state chemistry in fly ash",

abstract = "Fly ash represents a promising alternative source of rare earth elements (REE). However, information on REE containing mineral phases and their association with other fly ash components, vital for REE recovery from fly ash, is currently lacking. Herein, the mass fraction, distribution, crystallography and solid-state chemistry of REE, U and Th in Nigerian simulated fly ash samples were characterised using a range of laboratory and synchrotron x-ray based analytical techniques to underpin future extraction methodologies. Inductively coupled plasma mass spectrometry following full-acid digest of forty-five samples revealed recoverable average total REE content which ranged between 442 mgkg-1and 625 mgkg-1, comprising over 30wt% of the critical REE Nd, Eu, Tb, Dy, Y and Er. These REE within the fly ash samples were found to be most frequently associated with discrete monazite, xenotime and Y-bearing zircon mineral particles, with the former the most detected, which could be beneficiated through gravity separation. Analysis of monazite particles isolated from the composite samples through a complimentary suite of analytical synchrotron radiation techniques revealed a core-shell pattern, with the shell rich in colocalised Ce, Nd and La, and the core enrich in both U and Th. Ce in monazite was found to exist in a mixed trivalent and tetravalent oxidation state, with the monazite structure amorphized due to the high temperature combustion process. Such results demonstrate the strong co-association and physical distribution of REE, U and Th within monazite in fly ash; knowledge of which can subsequently be used to optimise or develop a more selective, cost-effective and environmentally friendly solvent extraction methodology, by targeting the strongly colocalised and surface bound REE in fly ash monazite particles. ",

keywords = "Nigeria, fly ash, rare earth elements, monazite, synchrotron radiation",

author = "Okeme, {Ilemona C} and Martin, {Peter George} and Jones, {Christopher P} and Crane, {Richard A.} and Ojonimi, {Theophilus Ile} and Konstantin Ignatyev and Scott, {Thomas Bligh}",

note = "Funding Information: The authors wish to thank Diamond Light Source for rapid access to beamline I18 (SP22876) that contributed to the results presented here. We would like to thank Sharon Uren (Senior Analytical Technician, Camborne School of Mines, University of Exeter) for performing the total acid digestion followed by ICP-MS analysis. We also wish to thank the Commonwealth Scholarship Commission for funding the PhD studentship. The SEM used in this work to conduct imaging and EDS analysis was purchased following funding by the Engineering and Physical Sciences Research Council (EPSRC), (Reference: EP/K040340/1). Funding Information: The authors wish to thank Diamond Light Source for rapid access to beamline I18 (SP22876) that contributed to the results presented here. We would like to thank Sharon Uren (Senior Analytical Technician, Camborne School of Mines, University of Exeter) for performing the total acid digestion followed by ICP-MS analysis. We also wish to thank the Commonwealth Scholarship Commission for funding the PhD studentship. Funding Information: The SEM used in this work to conduct imaging and EDS analysis was purchased following funding by the Engineering and Physical Sciences Research Council (EPSRC) , (Reference: EP/K040340/1 ). Publisher Copyright: {\textcopyright} 2020 Elsevier B.V.",

year = "2021",

month = mar,

day = "1",

doi = "10.1016/j.sab.2020.105950",

language = "English",

volume = "177",

journal = "Spectrochimica Acta Part B: Atomic Spectroscopy",

issn = "0584-8547",

publisher = "Amsterdam:Elsevier",

}

An advanced analytical assessment of rare earth element concentration, distribution, speciation, crystallography and solid-state chemistry in fly ash. / Okeme, Ilemona C; Martin, Peter George ; Jones, Christopher P et al.
In: Spectrochimica Acta Part B: Atomic Spectroscopy, Vol. 177, 105950, 01.03.2021.

Research output: Contribution to journal › Article (Academic Journal) › peer-review

TY - JOUR

T1 - An advanced analytical assessment of rare earth element concentration, distribution, speciation, crystallography and solid-state chemistry in fly ash

AU - Okeme, Ilemona C

AU - Martin, Peter George

AU - Jones, Christopher P

AU - Crane, Richard A.

AU - Ojonimi, Theophilus Ile

AU - Ignatyev, Konstantin

AU - Scott , Thomas Bligh

N1 - Funding Information: The authors wish to thank Diamond Light Source for rapid access to beamline I18 (SP22876) that contributed to the results presented here. We would like to thank Sharon Uren (Senior Analytical Technician, Camborne School of Mines, University of Exeter) for performing the total acid digestion followed by ICP-MS analysis. We also wish to thank the Commonwealth Scholarship Commission for funding the PhD studentship. The SEM used in this work to conduct imaging and EDS analysis was purchased following funding by the Engineering and Physical Sciences Research Council (EPSRC), (Reference: EP/K040340/1). Funding Information: The authors wish to thank Diamond Light Source for rapid access to beamline I18 (SP22876) that contributed to the results presented here. We would like to thank Sharon Uren (Senior Analytical Technician, Camborne School of Mines, University of Exeter) for performing the total acid digestion followed by ICP-MS analysis. We also wish to thank the Commonwealth Scholarship Commission for funding the PhD studentship. Funding Information: The SEM used in this work to conduct imaging and EDS analysis was purchased following funding by the Engineering and Physical Sciences Research Council (EPSRC) , (Reference: EP/K040340/1 ). Publisher Copyright: © 2020 Elsevier B.V.

PY - 2021/3/1

Y1 - 2021/3/1

N2 - Fly ash represents a promising alternative source of rare earth elements (REE). However, information on REE containing mineral phases and their association with other fly ash components, vital for REE recovery from fly ash, is currently lacking. Herein, the mass fraction, distribution, crystallography and solid-state chemistry of REE, U and Th in Nigerian simulated fly ash samples were characterised using a range of laboratory and synchrotron x-ray based analytical techniques to underpin future extraction methodologies. Inductively coupled plasma mass spectrometry following full-acid digest of forty-five samples revealed recoverable average total REE content which ranged between 442 mgkg-1and 625 mgkg-1, comprising over 30wt% of the critical REE Nd, Eu, Tb, Dy, Y and Er. These REE within the fly ash samples were found to be most frequently associated with discrete monazite, xenotime and Y-bearing zircon mineral particles, with the former the most detected, which could be beneficiated through gravity separation. Analysis of monazite particles isolated from the composite samples through a complimentary suite of analytical synchrotron radiation techniques revealed a core-shell pattern, with the shell rich in colocalised Ce, Nd and La, and the core enrich in both U and Th. Ce in monazite was found to exist in a mixed trivalent and tetravalent oxidation state, with the monazite structure amorphized due to the high temperature combustion process. Such results demonstrate the strong co-association and physical distribution of REE, U and Th within monazite in fly ash; knowledge of which can subsequently be used to optimise or develop a more selective, cost-effective and environmentally friendly solvent extraction methodology, by targeting the strongly colocalised and surface bound REE in fly ash monazite particles.

AB - Fly ash represents a promising alternative source of rare earth elements (REE). However, information on REE containing mineral phases and their association with other fly ash components, vital for REE recovery from fly ash, is currently lacking. Herein, the mass fraction, distribution, crystallography and solid-state chemistry of REE, U and Th in Nigerian simulated fly ash samples were characterised using a range of laboratory and synchrotron x-ray based analytical techniques to underpin future extraction methodologies. Inductively coupled plasma mass spectrometry following full-acid digest of forty-five samples revealed recoverable average total REE content which ranged between 442 mgkg-1and 625 mgkg-1, comprising over 30wt% of the critical REE Nd, Eu, Tb, Dy, Y and Er. These REE within the fly ash samples were found to be most frequently associated with discrete monazite, xenotime and Y-bearing zircon mineral particles, with the former the most detected, which could be beneficiated through gravity separation. Analysis of monazite particles isolated from the composite samples through a complimentary suite of analytical synchrotron radiation techniques revealed a core-shell pattern, with the shell rich in colocalised Ce, Nd and La, and the core enrich in both U and Th. Ce in monazite was found to exist in a mixed trivalent and tetravalent oxidation state, with the monazite structure amorphized due to the high temperature combustion process. Such results demonstrate the strong co-association and physical distribution of REE, U and Th within monazite in fly ash; knowledge of which can subsequently be used to optimise or develop a more selective, cost-effective and environmentally friendly solvent extraction methodology, by targeting the strongly colocalised and surface bound REE in fly ash monazite particles.

KW - Nigeria

KW - fly ash

KW - rare earth elements

KW - monazite

KW - synchrotron radiation

U2 - 10.1016/j.sab.2020.105950

DO - 10.1016/j.sab.2020.105950

M3 - Article (Academic Journal)

SN - 0584-8547

VL - 177

JO - Spectrochimica Acta Part B: Atomic Spectroscopy

JF - Spectrochimica Acta Part B: Atomic Spectroscopy

M1 - 105950

ER -

An advanced analytical assessment of rare earth element concentration, distribution, speciation, crystallography and solid-state chemistry in fly ash

Abstract

Bibliographical note

Keywords

Access to Document

Handle.net

Fingerprint

Cite this