XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2251
resin preparation, mixing with sample, curing and polish-
ing. The resin media used is a mix of epoxy resin and car-
bon black.
The copper deportment results obtained by the
Automated Mineralogy System revealed that copper is
available as two principal phases: native/metallic (composi-
tion Cu 100%), and “mixed sulfides” with the following
average composition, (wt. %):Cu 62.3, S 21.5, Fe 15.9,
and Zn 0.28. The modal mineralogy of the input slag as
given by the SEM-EDS indicated fayalite as principal min-
eral phase (gangue)—44.25%, while mixed sulfides were
present at 2% and native copper accounted to 0.87%.
Eh, pH, dissolved oxygen (DO) and temperature
monitoring
A TPS device-90-FLMV Field Lab analyzer equipped with
probes for oxidation reduction potential (ORP or Eh),
pH, Dissolved Oxygen (DO) and temperature was used
for monitoring pulp physicochemical properties. The ORP
probe measurements were referred against Ag/AgCl elec-
trode. Calibration was done for the pH and DO probes,
and drift correction for the ORP probe every 2–3 days.
When reporting redox potential readings, it is common
practice to refer them to the standard hydrogen electrode
(SHE), also known as the normal hydrogen electrode
(NHE). To accomplish this, a Eref value from Table 3 was
chosen, which corresponds to temperature of the solution.
By substituting the Eref value in the equation and solving
for Eh, the redox potential is determined.
Eh E Eref =+(1)
where, Eh: oxidation-reduction potential of the sample rel-
ative to the SHE, E: potential developed by the ORP elec-
trode, Eref: potential developed by the reference electrode
portion relative to SHE.
RESULTS &DISCUSSION
In total, 23 flotation experiments were conducted, with
all parameters, except temperature, maintained constant.
The registered values of Eh, pH and DO show a strong
correlation with temperature variations. It is generally
expected that since oxygen solubility in water increases as
temperature drops, the lower temperature ranges will bring
increased dissolved oxygen (DO) in the pulp compared to
higher temperatures. When interpretating the temperature
effects on Eh, pH, and DO in flotation, the results were
grouped into two temperature clusters, namely 15 and 20
°C and 30 and 35 °C. Figure 4 provides the mean values
for redox potential, DO and pH recorded within these two
temperature ranges.
With increase in temperature, redox potential is increas-
ing, while DO is decreasing. pH values do not witness mar-
ginal fluctuations with temperature variation. DO shows a
clear temperature dependent trend, with the solubility of
Figure 3. XRD pattern of the input slag
Table 3. Relation between temperature (°C) and Eh (mV)
Temperature (°C)
Redox Potential, mV
(Eref)
70 172.1
65 176.4
60 180.3
55 184.4
50 188.4
45 192.3
40 196.1
35 199.8
30 203.4
25 207.0
20 210.5
15 214.0
10 217.4
5 220.9
0 224.2
resin preparation, mixing with sample, curing and polish-
ing. The resin media used is a mix of epoxy resin and car-
bon black.
The copper deportment results obtained by the
Automated Mineralogy System revealed that copper is
available as two principal phases: native/metallic (composi-
tion Cu 100%), and “mixed sulfides” with the following
average composition, (wt. %):Cu 62.3, S 21.5, Fe 15.9,
and Zn 0.28. The modal mineralogy of the input slag as
given by the SEM-EDS indicated fayalite as principal min-
eral phase (gangue)—44.25%, while mixed sulfides were
present at 2% and native copper accounted to 0.87%.
Eh, pH, dissolved oxygen (DO) and temperature
monitoring
A TPS device-90-FLMV Field Lab analyzer equipped with
probes for oxidation reduction potential (ORP or Eh),
pH, Dissolved Oxygen (DO) and temperature was used
for monitoring pulp physicochemical properties. The ORP
probe measurements were referred against Ag/AgCl elec-
trode. Calibration was done for the pH and DO probes,
and drift correction for the ORP probe every 2–3 days.
When reporting redox potential readings, it is common
practice to refer them to the standard hydrogen electrode
(SHE), also known as the normal hydrogen electrode
(NHE). To accomplish this, a Eref value from Table 3 was
chosen, which corresponds to temperature of the solution.
By substituting the Eref value in the equation and solving
for Eh, the redox potential is determined.
Eh E Eref =+(1)
where, Eh: oxidation-reduction potential of the sample rel-
ative to the SHE, E: potential developed by the ORP elec-
trode, Eref: potential developed by the reference electrode
portion relative to SHE.
RESULTS &DISCUSSION
In total, 23 flotation experiments were conducted, with
all parameters, except temperature, maintained constant.
The registered values of Eh, pH and DO show a strong
correlation with temperature variations. It is generally
expected that since oxygen solubility in water increases as
temperature drops, the lower temperature ranges will bring
increased dissolved oxygen (DO) in the pulp compared to
higher temperatures. When interpretating the temperature
effects on Eh, pH, and DO in flotation, the results were
grouped into two temperature clusters, namely 15 and 20
°C and 30 and 35 °C. Figure 4 provides the mean values
for redox potential, DO and pH recorded within these two
temperature ranges.
With increase in temperature, redox potential is increas-
ing, while DO is decreasing. pH values do not witness mar-
ginal fluctuations with temperature variation. DO shows a
clear temperature dependent trend, with the solubility of
Figure 3. XRD pattern of the input slag
Table 3. Relation between temperature (°C) and Eh (mV)
Temperature (°C)
Redox Potential, mV
(Eref)
70 172.1
65 176.4
60 180.3
55 184.4
50 188.4
45 192.3
40 196.1
35 199.8
30 203.4
25 207.0
20 210.5
15 214.0
10 217.4
5 220.9
0 224.2