3
Chemicals
The chemicals employed in this study were of analytical
grade. Table 2 summarizes the chemicals used and their
purity.
Table 2. List of chemicals used in this study, including source
and purity
Chemicals Source Purity %
Choline Chloride Sigma-Aldrich 98%
Urea Sigma-Aldrich 99%
Ethylene Glycol Sigma-Aldrich 99%
Glycerol Sigma-Aldrich 99%
Lactic Acid Sigma-Aldrich 99%
Oxalic Acid Sigma-Aldrich 99%
Instruments and Equipment
A Ball Mill (TITAN Model) was used to crush the feed
sample. All the leach solutions were characterized by the
inductively coupled plasma mass spectrometry (ICP-MS)
Machine ThermoScientific (ICAP 6000 Series) at the
Bureau of Mines, Montana, and the Solid feed and resi-
due by the X-ray diffraction (Rigoku Ultima IV, available
at CAMP laboratory) machine (Bruker D8 discover) and
SEM equipped with an EDX-detector (TESCAN TIMA,
available at CAMP laboratory, Montana Technological
University, Butte, Montana, USA).
Preparation of Deep Eutectic Solvents
Ethaline and Reline were prepared by mixing a 1:2 mole
ratio for Choline Chloride: Ethylene Glycol and Choline
Chloride: Urea. Lactic Acid -Choline Chloride and
Glycerol-Choline Chloride combinations were ready at
a 2:1 ratio. The mixture was heated to 343 K and stirred
until clear homogenous solutions were formed. Oxaline
was based on a 1:1 composition ratio prepared for Choline
Chloride: Oxalic Acid and heated to 343 K until it formed a
clear homogeneous solution. The water content of the DES
was determined by the Mettler Toledo C20S Colorimetric
titrator, as shown in Figure 2, and the results shown in
Table 3.
Table 3. Percentage of Water in DES before Leaching
DES %Water
Within Range
(10%)
Oxaline 5 Yes
Reline 0.9 Yes
Ethaline 1.3 Yes
Choline Chloride – Lactic Acid 2.2 Yes
Choline Chloride – Glycerol 1.2 Yes
Feed Sample Preparation
The REE ore sample used for this study was obtained from
the Bear Lodge Mine, Wyoming. The ore sample was pul-
verized by Ball Mill (TITAN Model). The crushed product
was dry-sized using 280 μm and 250 μm screens and sieved
into three fractions: +280, –280+250, and –250 μm. All
experiments were performed with –280+250 μm fraction
except otherwise stated.
Characterization of the Feed Sample
Mineralogical characterization of the sample was carried
out using X-ray diffraction (XRD), and the result is shown
in Figures 3 and 4. The results showed that the feed sample
is mainly Micocline, Bastnasite, and Biotite, which form
the main minerals in the ore composition. SEM/EDX was
used for the surface morphology and elemental analysis of
the feed sample, and the result is shown in Figure 5 and
Table 4.
The results, shown in Table 4, indicate that cerium (Ce),
Lanthanum (La), Praesodymium (Pr), and Neodymium
Figure 2. Checking water content of DES before leaching
using Mettler Toledo C20S Coulometric Titrator
Chemicals
The chemicals employed in this study were of analytical
grade. Table 2 summarizes the chemicals used and their
purity.
Table 2. List of chemicals used in this study, including source
and purity
Chemicals Source Purity %
Choline Chloride Sigma-Aldrich 98%
Urea Sigma-Aldrich 99%
Ethylene Glycol Sigma-Aldrich 99%
Glycerol Sigma-Aldrich 99%
Lactic Acid Sigma-Aldrich 99%
Oxalic Acid Sigma-Aldrich 99%
Instruments and Equipment
A Ball Mill (TITAN Model) was used to crush the feed
sample. All the leach solutions were characterized by the
inductively coupled plasma mass spectrometry (ICP-MS)
Machine ThermoScientific (ICAP 6000 Series) at the
Bureau of Mines, Montana, and the Solid feed and resi-
due by the X-ray diffraction (Rigoku Ultima IV, available
at CAMP laboratory) machine (Bruker D8 discover) and
SEM equipped with an EDX-detector (TESCAN TIMA,
available at CAMP laboratory, Montana Technological
University, Butte, Montana, USA).
Preparation of Deep Eutectic Solvents
Ethaline and Reline were prepared by mixing a 1:2 mole
ratio for Choline Chloride: Ethylene Glycol and Choline
Chloride: Urea. Lactic Acid -Choline Chloride and
Glycerol-Choline Chloride combinations were ready at
a 2:1 ratio. The mixture was heated to 343 K and stirred
until clear homogenous solutions were formed. Oxaline
was based on a 1:1 composition ratio prepared for Choline
Chloride: Oxalic Acid and heated to 343 K until it formed a
clear homogeneous solution. The water content of the DES
was determined by the Mettler Toledo C20S Colorimetric
titrator, as shown in Figure 2, and the results shown in
Table 3.
Table 3. Percentage of Water in DES before Leaching
DES %Water
Within Range
(10%)
Oxaline 5 Yes
Reline 0.9 Yes
Ethaline 1.3 Yes
Choline Chloride – Lactic Acid 2.2 Yes
Choline Chloride – Glycerol 1.2 Yes
Feed Sample Preparation
The REE ore sample used for this study was obtained from
the Bear Lodge Mine, Wyoming. The ore sample was pul-
verized by Ball Mill (TITAN Model). The crushed product
was dry-sized using 280 μm and 250 μm screens and sieved
into three fractions: +280, –280+250, and –250 μm. All
experiments were performed with –280+250 μm fraction
except otherwise stated.
Characterization of the Feed Sample
Mineralogical characterization of the sample was carried
out using X-ray diffraction (XRD), and the result is shown
in Figures 3 and 4. The results showed that the feed sample
is mainly Micocline, Bastnasite, and Biotite, which form
the main minerals in the ore composition. SEM/EDX was
used for the surface morphology and elemental analysis of
the feed sample, and the result is shown in Figure 5 and
Table 4.
The results, shown in Table 4, indicate that cerium (Ce),
Lanthanum (La), Praesodymium (Pr), and Neodymium
Figure 2. Checking water content of DES before leaching
using Mettler Toledo C20S Coulometric Titrator