2190 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
ions can have one bond only with one atom on a mineral
surface. Certainly, Cl– and SO42– are present in solutions
but anions cannot activate mineral surfaces. Bond lengths
between two atoms are listed in Table 2.
To better understand the adsorption of different ions
on mineral surfaces, a theory based on theoretical calcula-
tions of bond lengths has been proposed. A bond length
between two atoms, provides an estimate of the binding
energy between two atoms. A longer bond length between
two atoms indicates weaker binding between atoms and
makes it easier to break or form, while a shorter bond length
between two atoms indicates stronger binding between
atoms and makes it more challenging to break or form. For
serpentine, talc, and pentlandite, the bond lengths follow a
pattern, with Ca2+ ions resulting in the longest bond length,
followed by Mg2+, Fe2+, and then Ni2+ (e.g., in the case
of serpentine, the bond lengths decrease in the following
order: serpentine-Ca (237 nm) serpentine-Mg (202 nm)
serpentine-Fe (179 nm) serpentine-Ni (173 nm) in
the case of talc, the bond lengths follow this order: talc-Ca
(237 nm) talc-Mg (202 nm) talc-Fe (179 nm) talc-Ni
(173 nm) for pentlandite, the bond lengths decrease in the
following order: pentlandite-Ca (274 nm) pentlandite-
Mg (242 nm) pentlandite-Fe (219 nm) pentlandite-Ni
(213 nm)). The order suggests that Ca2+ ions are particu-
larly effective at activating minerals compared to Ni2+ ions.
However, it is important to note that these findings are
based on theoretical calculations and need experimental
validation.
Microflotation Tests
2 g of minerals (pentlandite and/or lizardite) particles from
the fraction with a particle size range of +38–75 µm is used
for each microflotation experiment. MIBC with a concen-
tration of 30 ppm is used as frother, SEX with a concentra-
tion of 2×10–4 mol/L is used as a collector, CuSO4 solution
with a concentration of 1 wt.% is used as an activator, and
an air flowrate of 350 mL/min is selected. 250 µL SEX
solution, 2.5 mL MIBC solution, and the prepared acidic,
basic or electrolyte solutions are mixed to prepare 250 mL
solution to be used for microflotation of pentlandite and
lizardite, respectively.
During the microflotation process, firstly the com-
pressed air is turned on and the air flowrate is adjusted to
350 mL/mol. To minimize the particle blockage at the glass
frit, 30 mL of the mixture solution is added to the micro-
flotation column from the top, bubbling. 2 g of mineral
samples was weighted and stored in the small beaker, and
another 30 mL of the mixture solution was added to the
small beaker. The suspension is stirred manually with a
speed of 150 – 180 rpm/min and conditioned for 3 min.
The conditioned suspension is added to the microflota-
tion column from the top. Once the floated concentrate
starts to come out, the concentrate collection process starts.
The mineral concentrates were collected after 1, 4, 7 and
9 min. After collecting the second concentrate, 10 mL of
the mixture solution is added before collecting the third
and fourth concentrate. All the concentrates and tailing are
then filtered, air dried, and weighted for mass balance, and
cumulative recovery calculation.
After each microflotation experiment, the glass porous
frit was back blowed for 5 min with compressed air at a
pressure of 700 kPa (7 bar). After that, the glass porous frit
was immersed in the HCl solution with a molar concentra-
tion of 1 mol/L in a beaker and located in ultrasonic bath
and cleaned for around 10 min.
The selectivity index is defined as the recovery of pent-
landite divided by the recovery of lizardite at a specific con-
centrate collection time as shown in Equation 4.
SI R
RP
L
=(4)
RESULTS &DISCUSSIONS
Characterizations of Mineral Particles
XRD patterns of mineral samples are displayed in Figure 3,
(a) pentlandite, and (b) lizardite mineral sample. The XRD
peaks of different compositions in the mineral samples are
denoted in the figure based on the powder diffraction file
(PDF) numbers provided by the International Centre for
Table 2. Bond lengths between two atoms if the experiments are conducted in saline water
Bond Lengths Between Two Atoms
Pentlandite (nm)
(binding with 8 sulphur atoms
in one pentlandite molecule)
Serpentine (nm)
(binding with 10 oxygen atoms
in one serpentine molecule)
Ca2+ 274 237
Mg2+ 242 202
Fe2+ 219 213
Ni2+ 179 173
ions can have one bond only with one atom on a mineral
surface. Certainly, Cl– and SO42– are present in solutions
but anions cannot activate mineral surfaces. Bond lengths
between two atoms are listed in Table 2.
To better understand the adsorption of different ions
on mineral surfaces, a theory based on theoretical calcula-
tions of bond lengths has been proposed. A bond length
between two atoms, provides an estimate of the binding
energy between two atoms. A longer bond length between
two atoms indicates weaker binding between atoms and
makes it easier to break or form, while a shorter bond length
between two atoms indicates stronger binding between
atoms and makes it more challenging to break or form. For
serpentine, talc, and pentlandite, the bond lengths follow a
pattern, with Ca2+ ions resulting in the longest bond length,
followed by Mg2+, Fe2+, and then Ni2+ (e.g., in the case
of serpentine, the bond lengths decrease in the following
order: serpentine-Ca (237 nm) serpentine-Mg (202 nm)
serpentine-Fe (179 nm) serpentine-Ni (173 nm) in
the case of talc, the bond lengths follow this order: talc-Ca
(237 nm) talc-Mg (202 nm) talc-Fe (179 nm) talc-Ni
(173 nm) for pentlandite, the bond lengths decrease in the
following order: pentlandite-Ca (274 nm) pentlandite-
Mg (242 nm) pentlandite-Fe (219 nm) pentlandite-Ni
(213 nm)). The order suggests that Ca2+ ions are particu-
larly effective at activating minerals compared to Ni2+ ions.
However, it is important to note that these findings are
based on theoretical calculations and need experimental
validation.
Microflotation Tests
2 g of minerals (pentlandite and/or lizardite) particles from
the fraction with a particle size range of +38–75 µm is used
for each microflotation experiment. MIBC with a concen-
tration of 30 ppm is used as frother, SEX with a concentra-
tion of 2×10–4 mol/L is used as a collector, CuSO4 solution
with a concentration of 1 wt.% is used as an activator, and
an air flowrate of 350 mL/min is selected. 250 µL SEX
solution, 2.5 mL MIBC solution, and the prepared acidic,
basic or electrolyte solutions are mixed to prepare 250 mL
solution to be used for microflotation of pentlandite and
lizardite, respectively.
During the microflotation process, firstly the com-
pressed air is turned on and the air flowrate is adjusted to
350 mL/mol. To minimize the particle blockage at the glass
frit, 30 mL of the mixture solution is added to the micro-
flotation column from the top, bubbling. 2 g of mineral
samples was weighted and stored in the small beaker, and
another 30 mL of the mixture solution was added to the
small beaker. The suspension is stirred manually with a
speed of 150 – 180 rpm/min and conditioned for 3 min.
The conditioned suspension is added to the microflota-
tion column from the top. Once the floated concentrate
starts to come out, the concentrate collection process starts.
The mineral concentrates were collected after 1, 4, 7 and
9 min. After collecting the second concentrate, 10 mL of
the mixture solution is added before collecting the third
and fourth concentrate. All the concentrates and tailing are
then filtered, air dried, and weighted for mass balance, and
cumulative recovery calculation.
After each microflotation experiment, the glass porous
frit was back blowed for 5 min with compressed air at a
pressure of 700 kPa (7 bar). After that, the glass porous frit
was immersed in the HCl solution with a molar concentra-
tion of 1 mol/L in a beaker and located in ultrasonic bath
and cleaned for around 10 min.
The selectivity index is defined as the recovery of pent-
landite divided by the recovery of lizardite at a specific con-
centrate collection time as shown in Equation 4.
SI R
RP
L
=(4)
RESULTS &DISCUSSIONS
Characterizations of Mineral Particles
XRD patterns of mineral samples are displayed in Figure 3,
(a) pentlandite, and (b) lizardite mineral sample. The XRD
peaks of different compositions in the mineral samples are
denoted in the figure based on the powder diffraction file
(PDF) numbers provided by the International Centre for
Table 2. Bond lengths between two atoms if the experiments are conducted in saline water
Bond Lengths Between Two Atoms
Pentlandite (nm)
(binding with 8 sulphur atoms
in one pentlandite molecule)
Serpentine (nm)
(binding with 10 oxygen atoms
in one serpentine molecule)
Ca2+ 274 237
Mg2+ 242 202
Fe2+ 219 213
Ni2+ 179 173