XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2193
is the highest. Based on the experimental results and data
analysis, for pentlandite flotation, the CaCl2 concentration
has to be controlled to be around 0.1 mol/L to maintain
a high pentlandite recovery. More experiments with more
specific CaCl2 concentrations might need to be tested to
provide a precise molar concentration of CaCl2 to get the
highest selectivity index. However, in real operations on the
mine site, the main source of calcium is from the gangue
materials, and the molar concentration of Ca2+ is normally
very low, which can be treated as to have negligible influ-
ence on the pentlandite flotation.
The influence of MgCl2 with different molar concen-
trations on the microflotation of mineral samples are dis-
played in Figure 7. As can be seen from Figure 7 (a), the
highest pentlandite recovery is generated when the MgCl2
concentration is 0.1 mol/L among all molar concentrations
tested, further increasing the MgCl2 molar concentration
to 1 mol/L, the cumulative recovery of microflotation of
pentlandite samples decreases, ranking the lowest among
all molar concentrations tested. In Figure 7 (b), the highest
selectivity index is obtained under the experimental con-
dition when the MgCl2 molar concentration is 0.1 mol/L
among all molar concentrations tested. Further increasing
the MgCl2 concentration to 1.0 mol/L, the selectivity of
microflotation of pentlandite to lizardite decreases among
all concentrations tested. According to the microflotation
performance, to obtain a good flotation recovery of pent-
landite sample and high selectivity index of flotation of
pentlandite to lizardite, the MgCl2 concentration needs to
be controlled to be around 0.1 mol/L. More experiments
with more specific MgCl2 concentrations might need to be
tested to provide a precise molar concentration of MgCl2 to
get good flotation performance and selectivity index.
The influence of FeCl2 with different molar con-
centrations on the microflotation of mineral samples are
displayed in Figure 8. It is known to all that, in basic solu-
tions, Fe2+ hydrolyses, combines OH– and eventually
become Fe(OH)3 sediments, as shown in Equation 7 and
Equation 8, thus, Fe2+ only appears in pH neutral or acidic
solutions (Guimarães et al., 2007). Therefore, the effects of
FeCl2 on the microflotation of mineral samples are coop-
erative effects of FeCl2 and acidic experimental conditions.
The higher the FeCl2 concentration, due to the hydrolysis,
the lower the pH. This agrees with the experimental results
shown in Figure 5.
Fe2+ +H2O ⇌ Fe(OH)2 +2H+ (7)
4Fe(OH)2 +2H2O +O2 → Fe(OH)3↓ (8)
Based on trial experimental results, FeCl2 solutions are
unstable, within 24 hours, Fe2+ becomes Fe3+, the solution
colour changes from light green to dark brown. Besides,
the microflotation of pentlandite is only carried out suc-
cessfully in the presence of FeCl3 solution with a molar
concentration of 0.001 mol/L among all molar concen-
trations tested while the microflotation of lizardite is only
operated successfully in the presence of FeCl3 solution with
a molar concentration of 0.001 and 0.01 mol/L among all
concentrations tested. Combining the experimental results,
0 2 4 6 8 10
0
10
20
30
40
50
60
70
80
90
Time (min)
Influence of MgCl2 (mol/L)
Pentlandite Lizardite
0.001
0.01
0.1
1
(a)
0 2 4 6 8 10
0
10
20
30
40
50
Time (min)
MgCl2 molar concentration (mol/L)
0.001
0.01
0.1
1
(b)
Figure 7. (a) The influence of MgCl
2 with different molar concentrations on the microflotation of mineral samples (b) The
selectivity indexes generated under the same experimental conditions. The error bar stands for a standard error of the mean of
two independent runs
Cumul
ve
Recovery(%)
Selectivity
I
is the highest. Based on the experimental results and data
analysis, for pentlandite flotation, the CaCl2 concentration
has to be controlled to be around 0.1 mol/L to maintain
a high pentlandite recovery. More experiments with more
specific CaCl2 concentrations might need to be tested to
provide a precise molar concentration of CaCl2 to get the
highest selectivity index. However, in real operations on the
mine site, the main source of calcium is from the gangue
materials, and the molar concentration of Ca2+ is normally
very low, which can be treated as to have negligible influ-
ence on the pentlandite flotation.
The influence of MgCl2 with different molar concen-
trations on the microflotation of mineral samples are dis-
played in Figure 7. As can be seen from Figure 7 (a), the
highest pentlandite recovery is generated when the MgCl2
concentration is 0.1 mol/L among all molar concentrations
tested, further increasing the MgCl2 molar concentration
to 1 mol/L, the cumulative recovery of microflotation of
pentlandite samples decreases, ranking the lowest among
all molar concentrations tested. In Figure 7 (b), the highest
selectivity index is obtained under the experimental con-
dition when the MgCl2 molar concentration is 0.1 mol/L
among all molar concentrations tested. Further increasing
the MgCl2 concentration to 1.0 mol/L, the selectivity of
microflotation of pentlandite to lizardite decreases among
all concentrations tested. According to the microflotation
performance, to obtain a good flotation recovery of pent-
landite sample and high selectivity index of flotation of
pentlandite to lizardite, the MgCl2 concentration needs to
be controlled to be around 0.1 mol/L. More experiments
with more specific MgCl2 concentrations might need to be
tested to provide a precise molar concentration of MgCl2 to
get good flotation performance and selectivity index.
The influence of FeCl2 with different molar con-
centrations on the microflotation of mineral samples are
displayed in Figure 8. It is known to all that, in basic solu-
tions, Fe2+ hydrolyses, combines OH– and eventually
become Fe(OH)3 sediments, as shown in Equation 7 and
Equation 8, thus, Fe2+ only appears in pH neutral or acidic
solutions (Guimarães et al., 2007). Therefore, the effects of
FeCl2 on the microflotation of mineral samples are coop-
erative effects of FeCl2 and acidic experimental conditions.
The higher the FeCl2 concentration, due to the hydrolysis,
the lower the pH. This agrees with the experimental results
shown in Figure 5.
Fe2+ +H2O ⇌ Fe(OH)2 +2H+ (7)
4Fe(OH)2 +2H2O +O2 → Fe(OH)3↓ (8)
Based on trial experimental results, FeCl2 solutions are
unstable, within 24 hours, Fe2+ becomes Fe3+, the solution
colour changes from light green to dark brown. Besides,
the microflotation of pentlandite is only carried out suc-
cessfully in the presence of FeCl3 solution with a molar
concentration of 0.001 mol/L among all molar concen-
trations tested while the microflotation of lizardite is only
operated successfully in the presence of FeCl3 solution with
a molar concentration of 0.001 and 0.01 mol/L among all
concentrations tested. Combining the experimental results,
0 2 4 6 8 10
0
10
20
30
40
50
60
70
80
90
Time (min)
Influence of MgCl2 (mol/L)
Pentlandite Lizardite
0.001
0.01
0.1
1
(a)
0 2 4 6 8 10
0
10
20
30
40
50
Time (min)
MgCl2 molar concentration (mol/L)
0.001
0.01
0.1
1
(b)
Figure 7. (a) The influence of MgCl
2 with different molar concentrations on the microflotation of mineral samples (b) The
selectivity indexes generated under the same experimental conditions. The error bar stands for a standard error of the mean of
two independent runs
Cumul
ve
Recovery(%)
Selectivity
I