XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2265
in the flotation machine was adjusted to the required value
after dispersing the mineral particles in water for 2 min,
followed by adding the surfactant solution at the same pH.
pH was readjusted after 4 min followed by the flotation in
1 minute. The reported pH values were measured under
flotation conditions.
Hematite, malachite, and quartz were crushed and
milled in a planetary mill with a stainless-steel jar and stain-
less steel 30 mm balls, followed by wet sieving to obtain
a –20 µm fraction. The coarse (+38–90 µm) fraction was
prepared by dry sieving. To remove contaminations, hema-
tite and quartz particles were cleaned in a 0.01 M HCl
solution followed by washing in MilliQ water until neutral
pH is reached. The cleaning procedure for malachite was
eliminated due to its dissolution at acidic pH. Oxidized
cerium oxide particles, which we call CeO2(°x) hereafter,
were synthesized by sintering commercial 10-nm (99.9%)
CeO2 nanoparticles provided by Meliorum Technology. To
synthesize CeO2(°x), a 60:50 (w/w) mixture of the CeO2
nanoparticles with water was placed in a corundum jar and
dried overnight at 80 °C, followed by the calcination at
1000 °C in air for 3 h with a heating rate of 250 °C/h. The
final porous sample was crushed in a hand mill to obtain a
visually homogeneous powder which was used for the fur-
ther study.
The mineral particles were characterized using XRD,
SEM, and zeta-potential. The adsorption of the collectors
was studied using their adsorption density and the solubil-
ity of the minerals in the collector solutions measured after
2h of equilibration using total organic carbon (TOC) and
inductively coupled plasma mass spectrometry (ICP-MS),
respectively. Molecular-level insights were gained using
XPS. The spectra were measured after 2h of equilibration
and was aligned by setting the C 1s peak of adventitious
carbon at 285 eV. More technical details can be found else-
where [10, 13].
RESULTS
Flotation of Ultrafine Hematite and Malachite with
ASL, LSL, NaOl, and DDM
In this part, we compare ASL, LSL, NaOl, and DDM as
collectors in the two-mineral flotation of hematite and
malachite against quartz for ultrafine (–20 µm) and con-
ventional (+38 − 90 µm) particle size at pH 5–6 and 10.
For brevity, the conventional size fraction is called ‘coarse’
hereafter. The surfactant concentration is 50 µM, which is
lower than their CMC.
In the flotation of coarse hematite against ultrafine
quartz at pH 5 and 10, NaOl, LSL, and ASL produce hema-
tite grades of 65–70% (Figure 3a,b). The coarse malachite
grade is somewhat higher, being 75–80% and 65–75% at
Figure 2. Flotation flowsheet
c d a b
Figure 3. Recovery and grade in the flotation of a 1:1 (wt) mixture of ultrafine (–20 mm) and coarse (+38 − 90 µm) (a,b)
hematite and (c,d) malachite with ultrafine quartz with 50 µM () ASL, () LSL, () DDM, and () NaOl as
collectors at (a) pH 5 ± 0.3 and (b) pH 10 ± 0.3. The filled and empty symbols correspond to ultrafine and coarse hematite
particles, respectively. The error of the grade and recovery data points without the error bars is less than 5%. Copyright ©
2023, Slabov, Jain, Larsen, Rao Kota, and Chernyshova
in the flotation machine was adjusted to the required value
after dispersing the mineral particles in water for 2 min,
followed by adding the surfactant solution at the same pH.
pH was readjusted after 4 min followed by the flotation in
1 minute. The reported pH values were measured under
flotation conditions.
Hematite, malachite, and quartz were crushed and
milled in a planetary mill with a stainless-steel jar and stain-
less steel 30 mm balls, followed by wet sieving to obtain
a –20 µm fraction. The coarse (+38–90 µm) fraction was
prepared by dry sieving. To remove contaminations, hema-
tite and quartz particles were cleaned in a 0.01 M HCl
solution followed by washing in MilliQ water until neutral
pH is reached. The cleaning procedure for malachite was
eliminated due to its dissolution at acidic pH. Oxidized
cerium oxide particles, which we call CeO2(°x) hereafter,
were synthesized by sintering commercial 10-nm (99.9%)
CeO2 nanoparticles provided by Meliorum Technology. To
synthesize CeO2(°x), a 60:50 (w/w) mixture of the CeO2
nanoparticles with water was placed in a corundum jar and
dried overnight at 80 °C, followed by the calcination at
1000 °C in air for 3 h with a heating rate of 250 °C/h. The
final porous sample was crushed in a hand mill to obtain a
visually homogeneous powder which was used for the fur-
ther study.
The mineral particles were characterized using XRD,
SEM, and zeta-potential. The adsorption of the collectors
was studied using their adsorption density and the solubil-
ity of the minerals in the collector solutions measured after
2h of equilibration using total organic carbon (TOC) and
inductively coupled plasma mass spectrometry (ICP-MS),
respectively. Molecular-level insights were gained using
XPS. The spectra were measured after 2h of equilibration
and was aligned by setting the C 1s peak of adventitious
carbon at 285 eV. More technical details can be found else-
where [10, 13].
RESULTS
Flotation of Ultrafine Hematite and Malachite with
ASL, LSL, NaOl, and DDM
In this part, we compare ASL, LSL, NaOl, and DDM as
collectors in the two-mineral flotation of hematite and
malachite against quartz for ultrafine (–20 µm) and con-
ventional (+38 − 90 µm) particle size at pH 5–6 and 10.
For brevity, the conventional size fraction is called ‘coarse’
hereafter. The surfactant concentration is 50 µM, which is
lower than their CMC.
In the flotation of coarse hematite against ultrafine
quartz at pH 5 and 10, NaOl, LSL, and ASL produce hema-
tite grades of 65–70% (Figure 3a,b). The coarse malachite
grade is somewhat higher, being 75–80% and 65–75% at
Figure 2. Flotation flowsheet
c d a b
Figure 3. Recovery and grade in the flotation of a 1:1 (wt) mixture of ultrafine (–20 mm) and coarse (+38 − 90 µm) (a,b)
hematite and (c,d) malachite with ultrafine quartz with 50 µM () ASL, () LSL, () DDM, and () NaOl as
collectors at (a) pH 5 ± 0.3 and (b) pH 10 ± 0.3. The filled and empty symbols correspond to ultrafine and coarse hematite
particles, respectively. The error of the grade and recovery data points without the error bars is less than 5%. Copyright ©
2023, Slabov, Jain, Larsen, Rao Kota, and Chernyshova