XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2523
As can be seen from the zeta potential results presented
in Figure 3, repulsive forces become stronger at high pH,
however, the presence of more metallic adsorption sites is
more relevant because of the presence of iron and copper
hydroxides on the copper sulfide surfaces, which explains
the stronger adsorption and depressing effect of PAM at
higher pH values (Figures 2 and 4). At was previously indi-
cated, the pulp Eh values at which the flotation tests were
carried out varied between –50 and +20 mV/SHE, so for-
mation of metallic sites on the metal sulfide surfaces is pos-
sible (Hu et al., 2009). The experimental results indicate
that at high pH values, the electrostatic repulsion between
the polymer and mineral surfaces is surpassed which
induces more adsorption (Attia, 1992 Bahmani-Ghaedi
et al., 2022 Hocking et al., 1999). PAM adsorption on
mineral surfaces also depends on molecules conformation
which strongly depends on the ionization of the carboxylic
groups of PAMs. At high pH, carboxylic groups get strongly
ionized (Echeverry et al. 2021/2022) which strengthen the
interaction of the PAM molecules with the iron and copper
hydroxides formed on metal sulfide surfaces, both inducing
flotation depression. The experimental data show that the
depressing effect of the PAM on copper sulfide flotation
(Figure 2) and the specific adsorption (Figure 4) increase
as pH increases which support the proposed mechanism.
The zeta potential results presented in Figure 3 also indicate
-4.0 0.0 4.0 8.0 12.0 16.0 20.0 24.0 28.0
PAM concentration, m/L
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
Bornite
pH 8
pH 9
pH 10
0.0 4.0 8.0 12.0 16.0 20.0 24.0 28.0
PAM concentration, m/L
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
Enargite
pH 8
pH 9
pH 10
0.0 4.0 8.0 12.0 16.0 20.0 24.0 28.0
PAM concentration, m/L
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
Chalcopyrite
pH 8
pH 9
pH 10
Figure 4. Adsorption isotherms of PAM on chalcopyrite, enargite and bornite at pH values of 8, 9, and 10
Adsorption,
mg/g
Adsorption,
mg/g
Adsorption,
mg/g
As can be seen from the zeta potential results presented
in Figure 3, repulsive forces become stronger at high pH,
however, the presence of more metallic adsorption sites is
more relevant because of the presence of iron and copper
hydroxides on the copper sulfide surfaces, which explains
the stronger adsorption and depressing effect of PAM at
higher pH values (Figures 2 and 4). At was previously indi-
cated, the pulp Eh values at which the flotation tests were
carried out varied between –50 and +20 mV/SHE, so for-
mation of metallic sites on the metal sulfide surfaces is pos-
sible (Hu et al., 2009). The experimental results indicate
that at high pH values, the electrostatic repulsion between
the polymer and mineral surfaces is surpassed which
induces more adsorption (Attia, 1992 Bahmani-Ghaedi
et al., 2022 Hocking et al., 1999). PAM adsorption on
mineral surfaces also depends on molecules conformation
which strongly depends on the ionization of the carboxylic
groups of PAMs. At high pH, carboxylic groups get strongly
ionized (Echeverry et al. 2021/2022) which strengthen the
interaction of the PAM molecules with the iron and copper
hydroxides formed on metal sulfide surfaces, both inducing
flotation depression. The experimental data show that the
depressing effect of the PAM on copper sulfide flotation
(Figure 2) and the specific adsorption (Figure 4) increase
as pH increases which support the proposed mechanism.
The zeta potential results presented in Figure 3 also indicate
-4.0 0.0 4.0 8.0 12.0 16.0 20.0 24.0 28.0
PAM concentration, m/L
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
Bornite
pH 8
pH 9
pH 10
0.0 4.0 8.0 12.0 16.0 20.0 24.0 28.0
PAM concentration, m/L
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
Enargite
pH 8
pH 9
pH 10
0.0 4.0 8.0 12.0 16.0 20.0 24.0 28.0
PAM concentration, m/L
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
Chalcopyrite
pH 8
pH 9
pH 10
Figure 4. Adsorption isotherms of PAM on chalcopyrite, enargite and bornite at pH values of 8, 9, and 10
Adsorption,
mg/g
Adsorption,
mg/g
Adsorption,
mg/g