1
25-079
Selective Leaching of Rare Earth Elements from Complex Rare
Earth Ore Using Deep Eutectic Solvents
Mehran Sadat
Dept. of Metallurgical and Materials Engineering,
Montana Technological University, Butte, Montana
Richard LaDouceur
Dept. of Metallurgical and Materials Engineering,
Montana Technological University, Butte, Montana
Frank Agyemang
Dept. of Metallurgical and Materials Engineering,
Montana Technological University, Butte, Montana
Zainab Nasrullah
Dept. of Metallurgical and Materials Engineering,
Montana Technological University, Butte, Montana
ABSTRACT
Rare earth elements (REEs) are valuable for various modern
technological applications, including metallurgy, machine
building, radio electronics, instrument engineering, nuclear
engineering, and manufacturing. The extraction and separa-
tion of rare earth elements (REEs) from their complex ores
is challenging due to their distinct physical and chemical
properties, contributing to their market scarcity. At present,
REE recovery utilizes traditional pyro- or hydrometallurgi-
cal processes. The overall process in the recovery and sepa-
ration of individual elements from complex REE systems
suffers from high energy demands and the use of many haz-
ardous chemicals that negatively impact the environment.
With the growing trend toward a circular economy aim-
ing to balance sustainability, efficiency, and environmental
impacts, this research is focused on using deep eutectic sol-
vents (DESs): a combination of a quaternary salt: Choline
Chloride and five organic acids: Oxalic Acid, Urea, and
Ethylene Glycol, Lactic acid and Glycerol for the selective
leaching of REEs from their complex ore which is proven
to be green, selective, non-toxic, biodegradable, and cheap.
The effects of different DESs and leaching time on the REE
leaching efficiency we re determined, and the optimum
DES media were found to be Oxaline and Lactic Acid at
which a leaching efficiency of 25% and 15% was achieved
at 80°C respectively for cerium.
INTRODUCTION
Rare earth elements (REEs), due to their distinctive physi-
cal and chemical characteristics, are a vital component of
the green economy and cutting-edge technology [1], [2],
[3], as they are essential to the manufacturing of batteries,
permanent magnets, fluorescent lights, special alloys, ceram-
ics, and catalysts [4], [5], [6]. Together with yttrium (Y),
scandium (Sc), and lanthanides, rare earth elements consist
of 17 unique chemical elements [1]. Rare earth elements
are not equally distributed throughout the world 70%
of global production comes from China, followed by the
United States (14.33%), Australia (6%), Myanmar (4%),
Thailand (2.37%), Vietnam (1.43%), India (0.97%),
Russia (0.87%), Madagascar (0.32%), and the rest of the
world (0.03%) [7]. Many nations’ economic growth and
national security depend on REEs’ reliable supply and dura-
bility [8]. Still, the supply of rare earth elements currently
needs to be higher on the market since their availability is
currently less than demand [9], [10], with imports from
China frequently accounting for a large portion of the sup-
ply [11]. It is difficult to mine REEs since they are found in
minimal concentrations [5], and their extraction and sepa-
ration from their complex ore are complicated because of
their distinct physical and chemical qualities.
Traditional pyro- or hydrometallurgical processes are
currently employed in REE separation [12]. The pyromet-
allurgical method (roasting) has environmental concerns,
such as gaseous emissions, while the traditional hydromet-
allurgical process (leaching) involves the use of dilute and
robust acids (sulfuric acid, NaOH) [13], [14].
The recovery and separation of individual elements from
complex REE systems suffer from high energy demands as
they require complex energy-consuming solutions using
many hazardous chemicals that negatively impact the envi-
ronment [9]. In response to these REEs’ scarcity and poten-
tial supply risk and the current global worries regarding the
environmental effects of the mineral and metal industries,
25-079
Selective Leaching of Rare Earth Elements from Complex Rare
Earth Ore Using Deep Eutectic Solvents
Mehran Sadat
Dept. of Metallurgical and Materials Engineering,
Montana Technological University, Butte, Montana
Richard LaDouceur
Dept. of Metallurgical and Materials Engineering,
Montana Technological University, Butte, Montana
Frank Agyemang
Dept. of Metallurgical and Materials Engineering,
Montana Technological University, Butte, Montana
Zainab Nasrullah
Dept. of Metallurgical and Materials Engineering,
Montana Technological University, Butte, Montana
ABSTRACT
Rare earth elements (REEs) are valuable for various modern
technological applications, including metallurgy, machine
building, radio electronics, instrument engineering, nuclear
engineering, and manufacturing. The extraction and separa-
tion of rare earth elements (REEs) from their complex ores
is challenging due to their distinct physical and chemical
properties, contributing to their market scarcity. At present,
REE recovery utilizes traditional pyro- or hydrometallurgi-
cal processes. The overall process in the recovery and sepa-
ration of individual elements from complex REE systems
suffers from high energy demands and the use of many haz-
ardous chemicals that negatively impact the environment.
With the growing trend toward a circular economy aim-
ing to balance sustainability, efficiency, and environmental
impacts, this research is focused on using deep eutectic sol-
vents (DESs): a combination of a quaternary salt: Choline
Chloride and five organic acids: Oxalic Acid, Urea, and
Ethylene Glycol, Lactic acid and Glycerol for the selective
leaching of REEs from their complex ore which is proven
to be green, selective, non-toxic, biodegradable, and cheap.
The effects of different DESs and leaching time on the REE
leaching efficiency we re determined, and the optimum
DES media were found to be Oxaline and Lactic Acid at
which a leaching efficiency of 25% and 15% was achieved
at 80°C respectively for cerium.
INTRODUCTION
Rare earth elements (REEs), due to their distinctive physi-
cal and chemical characteristics, are a vital component of
the green economy and cutting-edge technology [1], [2],
[3], as they are essential to the manufacturing of batteries,
permanent magnets, fluorescent lights, special alloys, ceram-
ics, and catalysts [4], [5], [6]. Together with yttrium (Y),
scandium (Sc), and lanthanides, rare earth elements consist
of 17 unique chemical elements [1]. Rare earth elements
are not equally distributed throughout the world 70%
of global production comes from China, followed by the
United States (14.33%), Australia (6%), Myanmar (4%),
Thailand (2.37%), Vietnam (1.43%), India (0.97%),
Russia (0.87%), Madagascar (0.32%), and the rest of the
world (0.03%) [7]. Many nations’ economic growth and
national security depend on REEs’ reliable supply and dura-
bility [8]. Still, the supply of rare earth elements currently
needs to be higher on the market since their availability is
currently less than demand [9], [10], with imports from
China frequently accounting for a large portion of the sup-
ply [11]. It is difficult to mine REEs since they are found in
minimal concentrations [5], and their extraction and sepa-
ration from their complex ore are complicated because of
their distinct physical and chemical qualities.
Traditional pyro- or hydrometallurgical processes are
currently employed in REE separation [12]. The pyromet-
allurgical method (roasting) has environmental concerns,
such as gaseous emissions, while the traditional hydromet-
allurgical process (leaching) involves the use of dilute and
robust acids (sulfuric acid, NaOH) [13], [14].
The recovery and separation of individual elements from
complex REE systems suffer from high energy demands as
they require complex energy-consuming solutions using
many hazardous chemicals that negatively impact the envi-
ronment [9]. In response to these REEs’ scarcity and poten-
tial supply risk and the current global worries regarding the
environmental effects of the mineral and metal industries,