XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 677
These findings suggest that the use of FS milling media,
and pH conditions, may play a key role in the flotation of
ores due to the role which Fe species dissolved in solution
may play. These may be a result of the interaction between
Fe ions and the xanthate ions or due to the Fe ions promot-
ing galvanic interactions which reduce the floatability of
the Py mineral.
Pb Grade vs Recovery
This section analyses the Pb grade-recovery data obtained
from the mixed ore used in this study. Galena is often a
desired mineral in flotation concentrators hence the recov-
ery of Pb is of significant interest. Figure 4 shows that the
Pb grade ranged from 15–24 wt.% across all pHs. This is
probably due to the relatively strong adsorption of the xan-
thate collector onto Gn resulting in higher recoveries which
are not unduly influenced by the solids-water recoveries
shown in Figure 2.
Similar to the Fe grade-recovery trends for Py, Pb recov-
ery also increased when comparing pHs 4 and 10 for both
FS and Cer conditions. However, the low-recovery region is
primarily observed for FS-DI conditions at pH 6–8, with a
Pb recovery of 22.5% compared to 78.5 and 91.1% at pHs
4 and 10, respectively. The Pb recovery at pH 6–8 increased
to 81.1% at FS-SPW conditions but was still significantly
less than for Cer-DI and Cer-5SPW conditions, whose
recoveries were above 90% for the same pH level.
It is unclear why Pb recovery was significantly lower in
the FS-DI instance at pH 6–8 compared to other condi-
tions. However, a combination of effects may give a plau-
sible explanation for this phenomenon. Firstly, the same
poorly hydrophobic Fe(OH)X2 or the Fe(OH)X species
are also formed which negatively affects the adsorption of
more hydrophobic xanthate species on the surface of the
Gn. Furthermore, dissolved Pb can adsorbed onto the sur-
face of Gn as Pb(OH)+ or Pb2+, which also form poorly
hydrophobic complexes with xanthate [20], thus reducing
the effectiveness of the collector in floating Gn.
Figure 4 shows Pb recovery at FS-SPW conditions to
behave contrary to the expectation that it would be com-
parable to the data for FS-DI conditions. From an elec-
trochemical perspective, based on Figure 1, the higher
recovery for FS-5SPW can be attributed to a lower Eh of 59
mV vs 303 mV for the FS-DI condition. Dissolved SPW
ions therefore are responsible for creating a less oxidising
environment which facilitates better recoveries.
These findings show that dissolved Fe ions from the
media, and dissolved Pb from Gn can significantly affect
process recoveries. Furthermore, Gn flotation exhibits
more sensitivity to water type, particularly in cases where
the milling media contributes to Fe dissolution. However,
pH 4
pH
6-8
pH
10
pH 4
pH
6-8
pH
10
pH 4
pH
6-8
pH
10
pH 4
pH
6-8
pH
10
FS-DI FS-5SPW Cer-DI Cer-5SPW
Pb Grade 22,5 24,0 21,1 15,8 23,9 21,3 20,7 22,3 21,4 22,0 21,2 21,6
Pb Recovery 78,5 22,5 91,1 78,2 81,1 91,3 90,2 92,2 93,5 82,1 91,2 91,0
0
10
20
30
40
50
60
70
80
90
100
Figure 4. Effect of pH, milling media, and water composition on Pb grade and recovery
Pb
Grade
/
Recovery(%)
These findings suggest that the use of FS milling media,
and pH conditions, may play a key role in the flotation of
ores due to the role which Fe species dissolved in solution
may play. These may be a result of the interaction between
Fe ions and the xanthate ions or due to the Fe ions promot-
ing galvanic interactions which reduce the floatability of
the Py mineral.
Pb Grade vs Recovery
This section analyses the Pb grade-recovery data obtained
from the mixed ore used in this study. Galena is often a
desired mineral in flotation concentrators hence the recov-
ery of Pb is of significant interest. Figure 4 shows that the
Pb grade ranged from 15–24 wt.% across all pHs. This is
probably due to the relatively strong adsorption of the xan-
thate collector onto Gn resulting in higher recoveries which
are not unduly influenced by the solids-water recoveries
shown in Figure 2.
Similar to the Fe grade-recovery trends for Py, Pb recov-
ery also increased when comparing pHs 4 and 10 for both
FS and Cer conditions. However, the low-recovery region is
primarily observed for FS-DI conditions at pH 6–8, with a
Pb recovery of 22.5% compared to 78.5 and 91.1% at pHs
4 and 10, respectively. The Pb recovery at pH 6–8 increased
to 81.1% at FS-SPW conditions but was still significantly
less than for Cer-DI and Cer-5SPW conditions, whose
recoveries were above 90% for the same pH level.
It is unclear why Pb recovery was significantly lower in
the FS-DI instance at pH 6–8 compared to other condi-
tions. However, a combination of effects may give a plau-
sible explanation for this phenomenon. Firstly, the same
poorly hydrophobic Fe(OH)X2 or the Fe(OH)X species
are also formed which negatively affects the adsorption of
more hydrophobic xanthate species on the surface of the
Gn. Furthermore, dissolved Pb can adsorbed onto the sur-
face of Gn as Pb(OH)+ or Pb2+, which also form poorly
hydrophobic complexes with xanthate [20], thus reducing
the effectiveness of the collector in floating Gn.
Figure 4 shows Pb recovery at FS-SPW conditions to
behave contrary to the expectation that it would be com-
parable to the data for FS-DI conditions. From an elec-
trochemical perspective, based on Figure 1, the higher
recovery for FS-5SPW can be attributed to a lower Eh of 59
mV vs 303 mV for the FS-DI condition. Dissolved SPW
ions therefore are responsible for creating a less oxidising
environment which facilitates better recoveries.
These findings show that dissolved Fe ions from the
media, and dissolved Pb from Gn can significantly affect
process recoveries. Furthermore, Gn flotation exhibits
more sensitivity to water type, particularly in cases where
the milling media contributes to Fe dissolution. However,
pH 4
pH
6-8
pH
10
pH 4
pH
6-8
pH
10
pH 4
pH
6-8
pH
10
pH 4
pH
6-8
pH
10
FS-DI FS-5SPW Cer-DI Cer-5SPW
Pb Grade 22,5 24,0 21,1 15,8 23,9 21,3 20,7 22,3 21,4 22,0 21,2 21,6
Pb Recovery 78,5 22,5 91,1 78,2 81,1 91,3 90,2 92,2 93,5 82,1 91,2 91,0
0
10
20
30
40
50
60
70
80
90
100
Figure 4. Effect of pH, milling media, and water composition on Pb grade and recovery
Pb
Grade
/
Recovery(%)