2520 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
of 74 micrometers at a solids content of 25% by weight.
The grinding product was split into 3 samples later con-
ditioned during 3 minutes in 150 mL of solution (0.01M
NaCl) to adjust pH to the required condition using NaOH.
Later, PAX and MIBC were added at concentrations of 25
and 60 mg/L and conditioned for 3 minutes. Finally, PAM
was added and conditioned for additional 3 minutes after
which the resulting pulp was transferred to the cell to be
floated using 80 mL/min of nitrogen. After gas valve was
opened the froth was removed at 10-second intervals for
2 minutes. Tailings and concentrates and were then oven-
dried at 105 °C during 8 hours, and mineral recoveries were
calculated by dividing the mass of the concentrate by the
total mass of the concentrate plus tailings. All tests were
performed in triplicates and average values are reported
with the error bars being one standard deviation.
Zeta Potential Measurements
The interactions between the mineral particles and PAM
molecules were assessed by doing zeta potential measure-
ments using a Zetacompact Z9000 (CAD instrument,
Paris, France). This device uses video analysis to track fine
particles that get moving as an electric field is applied. The
quantity of particles monitored ranged from a few hundred
in closely clustered samples to several thousand in evenly
spread suspensions. 10 mL of suspension at 0.02% solids
content containing particles finer than 20 µm is injected to
the instrument’s quartz cell. All the tests were done in a
0.01M NaCl solution.
Adsorption Tests
PAM adsorption on copper sulfide minerals was assessed fol-
lowing the total organic carbon (TOC) in solution as mea-
sured by a TOC-L Shimadzu equipment. In the experiments,
1 g of copper mineral was dispersed during 15 minutes in
150 mL of PAM solutions at known varying concentrations
of the polymer, different pH values, and at 20 °C which was
controlled with a thermostatic bath. The experiments were
done in a 0.01M NaCl solution. The resulting suspensions
were centrifuged, filtered, and the liquid streams were ana-
lyzed for TOC from which the concentrations of PAM in
solution were obtained from a calibration curve.
The amounts of PAM adsorbed on copper sulfides
in mg/g were calculated from the PAM concentrations dif-
ferences in the initial (Ci) and final (Cf) solutions multiplied
by the volume of solution (150 mL). All these experiments
were performed in triplicate with an average standard error
of 3%. The Langmuir (Langmuir 1918) isotherm model
was fitted to the experimental data to describe the experi-
mental results.
RESULTS
Microflotation
Figure 2 shows the recovery of chalcopyrite, enargite and
bornite as a function of pH and at different PAM concen-
trations. The results show that PAM depresses the flotation
of the three copper minerals tested in this work. Besides,
the results indicate that the depressing effect of PAM on
the copper sulfides increases with pH. The pulp Eh values
at which the flotation tests were carried out varied between
–50 and +20 mV/SHE.
Zeta Potentials
Figure 3 shows the zeta potentials of copper sulfides as a
function of pH and different concentrations of PAM. The
results show that the zeta potentials become less negative
with the addition of PAM which indicates interactions
between the PAM molecules and the surfaces of the copper
sulfides.
Adsorption Isotherms
Figure 4 shows the equilibrium adsorption isotherms of
PAM on chalcopyrite, enargite and bornite at pH values
of 8, 9, and 10. The results indicate that as the concentra-
tion of PAM rises, the extent of adsorption also increases,
eventually reaching a saturation point which indicates that
adsorption occurs predominantly in a single layer (Butt
et al., 2013). The adsorption isotherms also indicate the
adsorption level of PAM in mg/g at different pH values,
results which show that adsorption increases with pH, a
trend that has been documented in previous studies on dif-
ferent systems and which correlates with the data presented
in Figure 2 (Butt et al., 2013 Wiśniewska et al., 2015).
The Langmuir (Langmuir 1918) isotherm model was
used to describe the experimental results. The linearized
Langmuir isotherm model is presented in Equation (1).
q qm K q C
1 1 1 1
e L m e $=+(1)
where qe is the amount of PAM (mg) adsorbed per g of
mineral at equilibrium, qm is the value of qe at the satu-
ration point, Ce is the equilibrium concentration (mg/L),
and KL is a Langmuir adsorption isotherm constant (L/mg)
which relates to adsorption energy. From a plot of 1/qe vs.
1/ Ce, the constants qm and KL can be determined from
the intersection and slope of the straight line, respectively.
Table 1 shows the Langmuir model constants, and Figure 5
shows the linearization of the model at the three pH values
tested.
of 74 micrometers at a solids content of 25% by weight.
The grinding product was split into 3 samples later con-
ditioned during 3 minutes in 150 mL of solution (0.01M
NaCl) to adjust pH to the required condition using NaOH.
Later, PAX and MIBC were added at concentrations of 25
and 60 mg/L and conditioned for 3 minutes. Finally, PAM
was added and conditioned for additional 3 minutes after
which the resulting pulp was transferred to the cell to be
floated using 80 mL/min of nitrogen. After gas valve was
opened the froth was removed at 10-second intervals for
2 minutes. Tailings and concentrates and were then oven-
dried at 105 °C during 8 hours, and mineral recoveries were
calculated by dividing the mass of the concentrate by the
total mass of the concentrate plus tailings. All tests were
performed in triplicates and average values are reported
with the error bars being one standard deviation.
Zeta Potential Measurements
The interactions between the mineral particles and PAM
molecules were assessed by doing zeta potential measure-
ments using a Zetacompact Z9000 (CAD instrument,
Paris, France). This device uses video analysis to track fine
particles that get moving as an electric field is applied. The
quantity of particles monitored ranged from a few hundred
in closely clustered samples to several thousand in evenly
spread suspensions. 10 mL of suspension at 0.02% solids
content containing particles finer than 20 µm is injected to
the instrument’s quartz cell. All the tests were done in a
0.01M NaCl solution.
Adsorption Tests
PAM adsorption on copper sulfide minerals was assessed fol-
lowing the total organic carbon (TOC) in solution as mea-
sured by a TOC-L Shimadzu equipment. In the experiments,
1 g of copper mineral was dispersed during 15 minutes in
150 mL of PAM solutions at known varying concentrations
of the polymer, different pH values, and at 20 °C which was
controlled with a thermostatic bath. The experiments were
done in a 0.01M NaCl solution. The resulting suspensions
were centrifuged, filtered, and the liquid streams were ana-
lyzed for TOC from which the concentrations of PAM in
solution were obtained from a calibration curve.
The amounts of PAM adsorbed on copper sulfides
in mg/g were calculated from the PAM concentrations dif-
ferences in the initial (Ci) and final (Cf) solutions multiplied
by the volume of solution (150 mL). All these experiments
were performed in triplicate with an average standard error
of 3%. The Langmuir (Langmuir 1918) isotherm model
was fitted to the experimental data to describe the experi-
mental results.
RESULTS
Microflotation
Figure 2 shows the recovery of chalcopyrite, enargite and
bornite as a function of pH and at different PAM concen-
trations. The results show that PAM depresses the flotation
of the three copper minerals tested in this work. Besides,
the results indicate that the depressing effect of PAM on
the copper sulfides increases with pH. The pulp Eh values
at which the flotation tests were carried out varied between
–50 and +20 mV/SHE.
Zeta Potentials
Figure 3 shows the zeta potentials of copper sulfides as a
function of pH and different concentrations of PAM. The
results show that the zeta potentials become less negative
with the addition of PAM which indicates interactions
between the PAM molecules and the surfaces of the copper
sulfides.
Adsorption Isotherms
Figure 4 shows the equilibrium adsorption isotherms of
PAM on chalcopyrite, enargite and bornite at pH values
of 8, 9, and 10. The results indicate that as the concentra-
tion of PAM rises, the extent of adsorption also increases,
eventually reaching a saturation point which indicates that
adsorption occurs predominantly in a single layer (Butt
et al., 2013). The adsorption isotherms also indicate the
adsorption level of PAM in mg/g at different pH values,
results which show that adsorption increases with pH, a
trend that has been documented in previous studies on dif-
ferent systems and which correlates with the data presented
in Figure 2 (Butt et al., 2013 Wiśniewska et al., 2015).
The Langmuir (Langmuir 1918) isotherm model was
used to describe the experimental results. The linearized
Langmuir isotherm model is presented in Equation (1).
q qm K q C
1 1 1 1
e L m e $=+(1)
where qe is the amount of PAM (mg) adsorbed per g of
mineral at equilibrium, qm is the value of qe at the satu-
ration point, Ce is the equilibrium concentration (mg/L),
and KL is a Langmuir adsorption isotherm constant (L/mg)
which relates to adsorption energy. From a plot of 1/qe vs.
1/ Ce, the constants qm and KL can be determined from
the intersection and slope of the straight line, respectively.
Table 1 shows the Langmuir model constants, and Figure 5
shows the linearization of the model at the three pH values
tested.