3154 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
weaker collector-mineral interaction is reflected by the high
rest potential drop, while stronger collector-mineral inter-
actions are denoted by low rest potential drop (Babedi et al.,
2023 Tadie et al., 2015). Figure 8b shows that a stronger
collector-chalcopyrite interaction was observed with a drop
in pH. The electrochemical results were consistent with the
microflotion test and collector adsorption results, reflecting
that monoclinic pyrrhotite was more detrimental to chalco-
pyrite flotation and the optimum flotation was achieved at
pH 9.5 and redox potential of –165 mV.
The electrochemical results establish a crucial funda-
mental link between the noble character of chalcopyrite and
its oxidation under flotation pulp conditions. The estab-
lished order of noble character aligned with the observed
flotation performance reported in the previous section.
This behaviour reflects that chalcopyrite flotation perfor-
mance is associated with its noble character (which controls
its oxidation rate). Lotter et al. (2016) established the rela-
tionship between noble character of sulphide minerals and
flotation performance, suggesting that more noble charac-
ter is associated with superior floatability. Such observations
were further highlighted by Babedi et al. (2023): Changes
in the noble character of sulphide minerals alters the rate
of oxidation and consequently the flotation performance.
Our results also showed that the oxidation of xanthate
to dixanthogen is dependent on both the pulp chemistry
and galvanic interaction. Lotter et al. (2016) and Bowden
and Young (2016) suggested that the flotation of chalco-
pyrite is attributed to the presence of dixanthogen. Such
observations are consistent with the results of this study
which showed optimum chalcopyrite flotation perfor-
mance was achieved only for chalcopyrite samples in the
presence of dixanthogen at pH 9.5 and –165 mV redox
potential. Conversely, the chalcopyrite that exhibited rest
potential below the xanthogen-dixanthogen line (indicat-
ing the absence of dixanthogen) and had poor flotation
performance. Our findings highlight the intricate interplay
between electrochemical behavior, noble character, and
Table 3. The change in corrosion potential of chalcopyrite as a function of its interaction
of with pyrrhotite at different pulp chemistry conditions
Sample ID pH ORP (mV) Ecorr (V)
Chalcopyrite 9 –275 –0.2069
Chalcopyrite 9.5 –165 –0.0221
Chalcopyrite 10 –193 –0.0266
Chalcopyrite +Hex Po 9 –275 –0.2204
Chalcopyrite +Hex Po 9.5 –165 –0.0320
Chalcopyrite +Hex Po 10 –193 –0.0363
Chalcopyrite +Mono Po 9 –275 –0.4338
Chalcopyrite +Mono Po 9.5 –165 –0.0781
Chalcopyrite +Mono Po 10 –193 –0.0557
Figure 7. Change in rest potential of chalcopyrite at different pH levels in the presence and absence of collector. Figure 7b
shows the change in the magnitude of the potential drop after the addition of collector at different pH levels
weaker collector-mineral interaction is reflected by the high
rest potential drop, while stronger collector-mineral inter-
actions are denoted by low rest potential drop (Babedi et al.,
2023 Tadie et al., 2015). Figure 8b shows that a stronger
collector-chalcopyrite interaction was observed with a drop
in pH. The electrochemical results were consistent with the
microflotion test and collector adsorption results, reflecting
that monoclinic pyrrhotite was more detrimental to chalco-
pyrite flotation and the optimum flotation was achieved at
pH 9.5 and redox potential of –165 mV.
The electrochemical results establish a crucial funda-
mental link between the noble character of chalcopyrite and
its oxidation under flotation pulp conditions. The estab-
lished order of noble character aligned with the observed
flotation performance reported in the previous section.
This behaviour reflects that chalcopyrite flotation perfor-
mance is associated with its noble character (which controls
its oxidation rate). Lotter et al. (2016) established the rela-
tionship between noble character of sulphide minerals and
flotation performance, suggesting that more noble charac-
ter is associated with superior floatability. Such observations
were further highlighted by Babedi et al. (2023): Changes
in the noble character of sulphide minerals alters the rate
of oxidation and consequently the flotation performance.
Our results also showed that the oxidation of xanthate
to dixanthogen is dependent on both the pulp chemistry
and galvanic interaction. Lotter et al. (2016) and Bowden
and Young (2016) suggested that the flotation of chalco-
pyrite is attributed to the presence of dixanthogen. Such
observations are consistent with the results of this study
which showed optimum chalcopyrite flotation perfor-
mance was achieved only for chalcopyrite samples in the
presence of dixanthogen at pH 9.5 and –165 mV redox
potential. Conversely, the chalcopyrite that exhibited rest
potential below the xanthogen-dixanthogen line (indicat-
ing the absence of dixanthogen) and had poor flotation
performance. Our findings highlight the intricate interplay
between electrochemical behavior, noble character, and
Table 3. The change in corrosion potential of chalcopyrite as a function of its interaction
of with pyrrhotite at different pulp chemistry conditions
Sample ID pH ORP (mV) Ecorr (V)
Chalcopyrite 9 –275 –0.2069
Chalcopyrite 9.5 –165 –0.0221
Chalcopyrite 10 –193 –0.0266
Chalcopyrite +Hex Po 9 –275 –0.2204
Chalcopyrite +Hex Po 9.5 –165 –0.0320
Chalcopyrite +Hex Po 10 –193 –0.0363
Chalcopyrite +Mono Po 9 –275 –0.4338
Chalcopyrite +Mono Po 9.5 –165 –0.0781
Chalcopyrite +Mono Po 10 –193 –0.0557
Figure 7. Change in rest potential of chalcopyrite at different pH levels in the presence and absence of collector. Figure 7b
shows the change in the magnitude of the potential drop after the addition of collector at different pH levels