XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3153
–275 mV, chalcopyrite exhibited the lowest rest potential,
regardless of the type of pyrrhotite superstructure in con-
tact. Accordingly, Abraitis et al. (2004), Tadie et al. (2015),
and Babedi et al. (2023) suggested that the magnitude of
rest potential exhibited by a mineral in the absence of a col-
lector denotes its noble character, with minerals being more
noble at higher rest potentials. Our results suggest that the
noble character of chalcopyrite depended on galvanic inter-
action and pulp chemistry. For example, at pH 9, chalco-
pyrite was least noble, as shown by the low rest potential,
while at pH 9.5, chalcopyrite was more noble. The order
of the noble character of chalcopyrite followed the trend:
chalcopyrite chalcopyrite +hexagonal pyrrhotite chal-
copyrite +monoclinic pyrrhotite. The rest potential results
were further corroborated by the polarization curve results,
which showed changes in the corrosion potential (Ecorr) as
a function of both galvanic interactions and pulp chemis-
try. Figure 6 shows the polarization curves of chalcopyrite
and its interactions with pyrrhotite at varying pH and
redox potential. Like the rest potential, the results shown in
Figure 6a-b and Table 3 demonstrated a decrease in Ecorr
as a function of pulp chemistry and galvanic interactions,
with the highest Ecorr exhibited by the more noble chalco-
pyrite without pyrrhotite at pH 9.5 and a redox potential
of –165 mV.
The results further illustrated that only chalcopyrite
without any interaction pyrrhotite at pH 9.5 and –165 mV
exhibited rest potential above the xanthate-dixanthogen
oxidation potential (0,15V) after the addition of collector
(Figure 7a and Table 2). The addition of collector across all
the other samples (chalcopyrite +hexagonal and chalcopy-
rite +monoclinic) resulted in rest potential values that were
below the xanthate-dixanthogen oxidation line (Table 2).
Babedi et al. (2023) and Tadie et al. (2015) illustrated that
the extend of the rest potential drop can be used to extrap-
olate the strength of mineral collector interaction. The
Table 2. The rest potential data of chalcopyrite in the presence and absence of collector
as a function of its interaction with pyrrhotite and variation in pulp chemistry variables
Sample pH
ORP
(mV) Before After Drop
Chalcopyrite 9 –275 0.1200 0.0940 0.0260
Chalcopyrite 9.5 –165 0.1980 0.1640 0.0340
Chalcopyrite 10 –193 0.1850 0.1110 0.0740
Chalcopyrite+Hex 9 –275 0.1700 0.1070 0.0630
Chalcopyrite+Hex 9.5 –165 0.1720 0.1480 0.0240
Chalcopyrite+Hex 10 –193 0.1790 0.0397 0.1393
Chalcopyrite+Mono 9 –275 0.0575 –0.0184 0.0391
Chalcopyrite+Mono 9.5 –165 0.1570 0.1360 0.0210
Chalcopyrite+Mono 10 –193 0.1690 0.0909 0.0781
Figure 6. Polarization curve profiles (6a) and the change in corrosion potential (6b) for chalcopyrite at different pulp
chemistry variables
–275 mV, chalcopyrite exhibited the lowest rest potential,
regardless of the type of pyrrhotite superstructure in con-
tact. Accordingly, Abraitis et al. (2004), Tadie et al. (2015),
and Babedi et al. (2023) suggested that the magnitude of
rest potential exhibited by a mineral in the absence of a col-
lector denotes its noble character, with minerals being more
noble at higher rest potentials. Our results suggest that the
noble character of chalcopyrite depended on galvanic inter-
action and pulp chemistry. For example, at pH 9, chalco-
pyrite was least noble, as shown by the low rest potential,
while at pH 9.5, chalcopyrite was more noble. The order
of the noble character of chalcopyrite followed the trend:
chalcopyrite chalcopyrite +hexagonal pyrrhotite chal-
copyrite +monoclinic pyrrhotite. The rest potential results
were further corroborated by the polarization curve results,
which showed changes in the corrosion potential (Ecorr) as
a function of both galvanic interactions and pulp chemis-
try. Figure 6 shows the polarization curves of chalcopyrite
and its interactions with pyrrhotite at varying pH and
redox potential. Like the rest potential, the results shown in
Figure 6a-b and Table 3 demonstrated a decrease in Ecorr
as a function of pulp chemistry and galvanic interactions,
with the highest Ecorr exhibited by the more noble chalco-
pyrite without pyrrhotite at pH 9.5 and a redox potential
of –165 mV.
The results further illustrated that only chalcopyrite
without any interaction pyrrhotite at pH 9.5 and –165 mV
exhibited rest potential above the xanthate-dixanthogen
oxidation potential (0,15V) after the addition of collector
(Figure 7a and Table 2). The addition of collector across all
the other samples (chalcopyrite +hexagonal and chalcopy-
rite +monoclinic) resulted in rest potential values that were
below the xanthate-dixanthogen oxidation line (Table 2).
Babedi et al. (2023) and Tadie et al. (2015) illustrated that
the extend of the rest potential drop can be used to extrap-
olate the strength of mineral collector interaction. The
Table 2. The rest potential data of chalcopyrite in the presence and absence of collector
as a function of its interaction with pyrrhotite and variation in pulp chemistry variables
Sample pH
ORP
(mV) Before After Drop
Chalcopyrite 9 –275 0.1200 0.0940 0.0260
Chalcopyrite 9.5 –165 0.1980 0.1640 0.0340
Chalcopyrite 10 –193 0.1850 0.1110 0.0740
Chalcopyrite+Hex 9 –275 0.1700 0.1070 0.0630
Chalcopyrite+Hex 9.5 –165 0.1720 0.1480 0.0240
Chalcopyrite+Hex 10 –193 0.1790 0.0397 0.1393
Chalcopyrite+Mono 9 –275 0.0575 –0.0184 0.0391
Chalcopyrite+Mono 9.5 –165 0.1570 0.1360 0.0210
Chalcopyrite+Mono 10 –193 0.1690 0.0909 0.0781
Figure 6. Polarization curve profiles (6a) and the change in corrosion potential (6b) for chalcopyrite at different pulp
chemistry variables