XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1687
ionic liquids in that they are mixtures rather than isolated
salt compounds, their anhydrous nature, and shared char-
acteristics make them suitable for metal recovery. Choline
Chloride [ChCl, HOC2H4N+(CH3)3Cl) is widely used as
a halide salt. There are types of DES systems. Table 1 shows
the classification of DESs formed based on the nature of
the complexing agent used.
The Type III DESs namely Reline (Choline Chloride
1: 2 Urea), Ethaline (Choline Chloride 1: 2 Ethylene
Glycol), Oxaline (Choline Chloride 1: 1 Oxalic Acid) and
EG: TBAC (Ethylene Glycol 2: 1 Tetrabutylammonium
Chloride) were used for this research due to their advan-
tages over the other types of DESs that make them useful
for large-scale industrial processes. Some of their advan-
tages include the ability to solvate a wide range of transition
metal species including chlorides [25], oxides [26], and
rare earth elements, simple to prepare, relatively unreactive
with water, relatively low cost, and biodegradable nature of
many [27], [28], [29].
Typically, one of the major drawbacks of leaching is
slow kinetics [30]. DESs have higher viscosity than aque-
ous solvents [16], [31] and since chemical reactions have
slow kinetics in viscous liquids [31], the leaching kinetics
may be greatly affected. Water can be added to DESs to
reduce their viscosity but the addition of water or too much
water, can change its physicochemical properties [31], [32].
Increasing the temperature is another way to reduce the
viscosity [21], [31] but this may increase the cost of opera-
tion on an industrial scale. For this reason, RAM will be
used to intensify the leaching process. RAM uses resonant
vibration to speed up homogeneity and motion [33]. RAM
mixers work by creating and regulating vertical motion by
consuming minimal power, which moves and vibrates the
resonator plate, affecting the contents of the mixing ves-
sel being utilized. RAM systems are particularly effective
because they balance frequency and displacement, unlike
other mixing technologies like ultrasonics which func-
tion at very high frequencies but only generate displace-
ment within a small area immediately surrounding the
frequency-generating probe [34]. The intensification will
shorten leaching time by increasing leaching kinetics and
overall leaching efficiency or recovery thereby cutting down
operational cost. The intensification process accelerates the
diffusion process by causing a change in the hydrodynamic
situation in the interfacial layer and the adjacent layers
of liquids due to the supply of additional energy and the
updating of the phase contact surface [35].
MATERIALS AND METHODS
The specifications of the chemicals: Choline Chloride
(C5H14NO·Cl), Tetra Butyl Ammonium Chloride
(C16H36ClN), Oxalic Acid (C2H2O4), Ethylene Glycol
(CH2OH)2), Urea (CO(NH2)2) were sourced from
ThermoScientific with purity of 98.99%. They were used
as received for research purposes. Sm-Co magnets were pro-
vided by Integrated Magnets Inc, Culver City, California,
USA. Ball Mill (TITAN Model) and mortar and pestle
were utilized for size reduction of Sm-Co magnets. To
achieve a representative sample from the bulk of Sm-Co
magnets, ASTM standard D6323-98 was followed. Coning
and quartering and a riffle splitter were used for homog-
enization and sampling. For sieving, sieves (W.S. Tyler) of
mesh numbers of 40, 60 and 200 were used. The magnetic
stirrer hot plate (IKA RET control VISC S000) and reso-
nant vibratory mixer (Resodyn LabRAM II) were used to
perform the leaching and mixing experiments.
Characterization
In this research study, Scanning Electron Microscopy (SEM)
was used to visualize the microstructure and morphology
of ground Sm-Co. X-ray diffraction (XRD) analysis was
incorporated to understand the presence of different crystal
structures in the Sm-Co sample. For the initial grade (%)
and after leaching concentration analysis in terms of recov-
ery (%),Inductively Coupled Plasma–Optical Spectroscopy
(ICP-OES) was extensively utilized, and results were drawn
from the data. Energy Dispersive Spectroscopy (EDS) was
also used along with SEM to quantify the presence of ele-
ments in Sm-Co sample.
Table 1. General formula for classification of deep eutectic solvents. These are classified based on the nature of the complexing
agent used. Type I is an analogous combination between the metal chloride and quaternary ammonium salts, type II is based
on the combination of hydrated metal chloride and salt, type III is based on the combination of transition metal and salt, and
type IV is based on a wide range of transition metals combined with inorganic cations to form a eutectic [25]
Type General Formula Terms
Type I Cat+X–ZMClx M =Zn, Sn, Fe, Al, Ga
Type II Cat+X–ZMClx.yH2O M =Cr, Co, Cu, Ni, Fe
Type III Cat+X–
Z RZ Z= CONH
2 ,COOH, OH
Type IV MCl
x +RZ =MCl
x-1 *RZ +MCl
x-1 M =Al, Zn and Z =CONH
2 ,OH
ionic liquids in that they are mixtures rather than isolated
salt compounds, their anhydrous nature, and shared char-
acteristics make them suitable for metal recovery. Choline
Chloride [ChCl, HOC2H4N+(CH3)3Cl) is widely used as
a halide salt. There are types of DES systems. Table 1 shows
the classification of DESs formed based on the nature of
the complexing agent used.
The Type III DESs namely Reline (Choline Chloride
1: 2 Urea), Ethaline (Choline Chloride 1: 2 Ethylene
Glycol), Oxaline (Choline Chloride 1: 1 Oxalic Acid) and
EG: TBAC (Ethylene Glycol 2: 1 Tetrabutylammonium
Chloride) were used for this research due to their advan-
tages over the other types of DESs that make them useful
for large-scale industrial processes. Some of their advan-
tages include the ability to solvate a wide range of transition
metal species including chlorides [25], oxides [26], and
rare earth elements, simple to prepare, relatively unreactive
with water, relatively low cost, and biodegradable nature of
many [27], [28], [29].
Typically, one of the major drawbacks of leaching is
slow kinetics [30]. DESs have higher viscosity than aque-
ous solvents [16], [31] and since chemical reactions have
slow kinetics in viscous liquids [31], the leaching kinetics
may be greatly affected. Water can be added to DESs to
reduce their viscosity but the addition of water or too much
water, can change its physicochemical properties [31], [32].
Increasing the temperature is another way to reduce the
viscosity [21], [31] but this may increase the cost of opera-
tion on an industrial scale. For this reason, RAM will be
used to intensify the leaching process. RAM uses resonant
vibration to speed up homogeneity and motion [33]. RAM
mixers work by creating and regulating vertical motion by
consuming minimal power, which moves and vibrates the
resonator plate, affecting the contents of the mixing ves-
sel being utilized. RAM systems are particularly effective
because they balance frequency and displacement, unlike
other mixing technologies like ultrasonics which func-
tion at very high frequencies but only generate displace-
ment within a small area immediately surrounding the
frequency-generating probe [34]. The intensification will
shorten leaching time by increasing leaching kinetics and
overall leaching efficiency or recovery thereby cutting down
operational cost. The intensification process accelerates the
diffusion process by causing a change in the hydrodynamic
situation in the interfacial layer and the adjacent layers
of liquids due to the supply of additional energy and the
updating of the phase contact surface [35].
MATERIALS AND METHODS
The specifications of the chemicals: Choline Chloride
(C5H14NO·Cl), Tetra Butyl Ammonium Chloride
(C16H36ClN), Oxalic Acid (C2H2O4), Ethylene Glycol
(CH2OH)2), Urea (CO(NH2)2) were sourced from
ThermoScientific with purity of 98.99%. They were used
as received for research purposes. Sm-Co magnets were pro-
vided by Integrated Magnets Inc, Culver City, California,
USA. Ball Mill (TITAN Model) and mortar and pestle
were utilized for size reduction of Sm-Co magnets. To
achieve a representative sample from the bulk of Sm-Co
magnets, ASTM standard D6323-98 was followed. Coning
and quartering and a riffle splitter were used for homog-
enization and sampling. For sieving, sieves (W.S. Tyler) of
mesh numbers of 40, 60 and 200 were used. The magnetic
stirrer hot plate (IKA RET control VISC S000) and reso-
nant vibratory mixer (Resodyn LabRAM II) were used to
perform the leaching and mixing experiments.
Characterization
In this research study, Scanning Electron Microscopy (SEM)
was used to visualize the microstructure and morphology
of ground Sm-Co. X-ray diffraction (XRD) analysis was
incorporated to understand the presence of different crystal
structures in the Sm-Co sample. For the initial grade (%)
and after leaching concentration analysis in terms of recov-
ery (%),Inductively Coupled Plasma–Optical Spectroscopy
(ICP-OES) was extensively utilized, and results were drawn
from the data. Energy Dispersive Spectroscopy (EDS) was
also used along with SEM to quantify the presence of ele-
ments in Sm-Co sample.
Table 1. General formula for classification of deep eutectic solvents. These are classified based on the nature of the complexing
agent used. Type I is an analogous combination between the metal chloride and quaternary ammonium salts, type II is based
on the combination of hydrated metal chloride and salt, type III is based on the combination of transition metal and salt, and
type IV is based on a wide range of transition metals combined with inorganic cations to form a eutectic [25]
Type General Formula Terms
Type I Cat+X–ZMClx M =Zn, Sn, Fe, Al, Ga
Type II Cat+X–ZMClx.yH2O M =Cr, Co, Cu, Ni, Fe
Type III Cat+X–
Z RZ Z= CONH
2 ,COOH, OH
Type IV MCl
x +RZ =MCl
x-1 *RZ +MCl
x-1 M =Al, Zn and Z =CONH
2 ,OH