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Preliminary Investigation of Using Deep Eutectic Solvents for
REE Dissolution from Primary Ores and Mine Tailings
Yamini K, Laurence Dyer
Western Australian School of Mines: Minerals, Energy, and Chemical Engineering, Faculty of Science and Engineering,
Curtin University, Kalgoorlie.
ABSTRACT: The increasing emphasis on green chemistry has led numerous researchers to focus on
environmentally friendly solvents for mineral extraction. One such class of green solvents are Deep Eutectic
Solvents (DES). DESs comprise a hydrogen bond donor and a hydrogen bond acceptor and are characterised
by significant depressions in melting points compared to their constituent components. They have garnered
attention due to their eco-friendly, non-toxic, and bio-degradable properties. These solvents possess comparable
physicochemical properties to conventional ionic liquids but are more cost-effective and environmentally
friendly. Extensive research has been dedicated to using DES to extract valuable metals from synthetic materials
and minerals. However, limited attention has been given to exploring their potential with primary ores and
primary waste materials. To address this knowledge gap, the present study investigated the applicability of DES
to extract rare earth elements from primary sources and wastes to understand how different materials respond
to them.
The feedstocks targeted for this study include sub-economic ores with varying grades and mineralogy, mona-
zite flotation tailings, and acid crack and leach residues. This study will serve as a scoping analysis to assess the
response of each feed material and its associated mineralogy to the prepared solvents. Furthermore, a compari-
son has been drawn between the leach performance of DES systems and other leach systems.
Keywords: Deep eutectic solvents, reline, ethaline, green chemistry.
INTRODUCTION
Rare earth elements (REEs) are 17 elements that include
the lanthanide series, scandium, and yttrium. These ele-
ments are classified into light rare earths and heavy rare
earths. They are widely used in high-tech applications due
to their unique magnetic, optical, and electronic properties
produced by the orbital electrons in the 4f subshell (Gupta
and Krishnamurthy 1992). These elements are commonly
processed from monazite, bastnasite, and xenotime (Gupta
and Krishnamurthy 1992). Owing to their increasing
applications in the automobile, electronic, and medical sec-
tors, these elements have been listed as critical minerals in
the list published by the USGS, European Commission,
and the Australian Government.
The demand for critical and strategic metals increases
as the world moves towards clean technologies. With the
increasing demand for these metals, it is necessary that we
process them from low-grade ores and secondary sources like
mine tailings, by-products generated from the conventional
processing route, and discarded electronic wastes (Yamini
Preliminary Investigation of Using Deep Eutectic Solvents for
REE Dissolution from Primary Ores and Mine Tailings
Yamini K, Laurence Dyer
Western Australian School of Mines: Minerals, Energy, and Chemical Engineering, Faculty of Science and Engineering,
Curtin University, Kalgoorlie.
ABSTRACT: The increasing emphasis on green chemistry has led numerous researchers to focus on
environmentally friendly solvents for mineral extraction. One such class of green solvents are Deep Eutectic
Solvents (DES). DESs comprise a hydrogen bond donor and a hydrogen bond acceptor and are characterised
by significant depressions in melting points compared to their constituent components. They have garnered
attention due to their eco-friendly, non-toxic, and bio-degradable properties. These solvents possess comparable
physicochemical properties to conventional ionic liquids but are more cost-effective and environmentally
friendly. Extensive research has been dedicated to using DES to extract valuable metals from synthetic materials
and minerals. However, limited attention has been given to exploring their potential with primary ores and
primary waste materials. To address this knowledge gap, the present study investigated the applicability of DES
to extract rare earth elements from primary sources and wastes to understand how different materials respond
to them.
The feedstocks targeted for this study include sub-economic ores with varying grades and mineralogy, mona-
zite flotation tailings, and acid crack and leach residues. This study will serve as a scoping analysis to assess the
response of each feed material and its associated mineralogy to the prepared solvents. Furthermore, a compari-
son has been drawn between the leach performance of DES systems and other leach systems.
Keywords: Deep eutectic solvents, reline, ethaline, green chemistry.
INTRODUCTION
Rare earth elements (REEs) are 17 elements that include
the lanthanide series, scandium, and yttrium. These ele-
ments are classified into light rare earths and heavy rare
earths. They are widely used in high-tech applications due
to their unique magnetic, optical, and electronic properties
produced by the orbital electrons in the 4f subshell (Gupta
and Krishnamurthy 1992). These elements are commonly
processed from monazite, bastnasite, and xenotime (Gupta
and Krishnamurthy 1992). Owing to their increasing
applications in the automobile, electronic, and medical sec-
tors, these elements have been listed as critical minerals in
the list published by the USGS, European Commission,
and the Australian Government.
The demand for critical and strategic metals increases
as the world moves towards clean technologies. With the
increasing demand for these metals, it is necessary that we
process them from low-grade ores and secondary sources like
mine tailings, by-products generated from the conventional
processing route, and discarded electronic wastes (Yamini