2524 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
that the interactions between PAM molecules and the sur-
faces of copper sulfides become stronger at higher pH val-
ues. Figure 3 shows that the zeta potential changes caused
by the presence of PAM are relevant at higher pH values,
however, there are no changes on the isoelectric points. This
trend aligns with the concept that at higher pH levels, the
surfaces of copper sulfides and PAM become more reac-
tive, leading to increased adsorption. Conversely, at lower
pH levels, the reactivity of both materials is reduced, which
explains the lack of changes in the IEP.
The effects of PAM molecules on chalcopyrite, enar-
gite and bornite flotation, zeta potentials, and adsorption
trends presented in Figures 2 to 4 are similarly significant
in scale. Chalcopyrite is a copper sulfide that exhibits natu-
ral hydrophobicity at low pH and under a range of redox
potential of 100–500 mV/NHE (Heyes, 1997 Leja, 1981).
The natural floatability of chalcopyrite decreases with pH
causing the potential range to narrow due to the forma-
tion of iron and copper hydroxides on the surface sites on
which anionic PAM molecules tend to adsorb causing low
recoveries. The enargite surface properties in flotation were
previously investigated (Kantar, 2002 Plackowski et al.,
2012 Guo and Yen, 2002 Yepsen et al., 2019 Yepsen and
Gutierrez, 2020). It was reported that enargite flotation is
affected by pH and pulp redox potential, i.e., collectorless
flotation is good at low pH and high Eh which is explained
0,0 0,1 0,2 0,3
1/Ce, L/mg
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
4,5
5,0
Chalcopyrite
pH 8
pH 9
pH 10
1/qe =16.8 (1/Ce) +0.15 R 2 =0.98
1/qe =9.59 (1/Ce) +0.48 R 2 =0.98
1/qe =8.67 (1/Ce) +0.43 R 2 =0.99
0,0 0,1 0,2 0,3 0,4 0,5
1/Ce, L/mg
0,0
0,5
1,0
1,5
2,0
2,5
3,0
Enargite
pH 8
pH 9
pH 10
1/qe =5.34 (1/Ce) +0.53 R 2 =0.99
1/qe =5.49 (1/Ce) +0.41 R 2 =0.98
1/qe =5.17 (1/Ce) +0.38 R 2 =0.97
0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9
1/Ce, L/mg
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
4,5
5,0
Bornite
pH 8
pH 9
pH 10
1/qe =4.82 (1/Ce) +0.61 R 2 =0.996
1/qe =2.15 (1/Ce) +0.80 R 2 =0.98
1/qe =2.03 (1/Ce) +0.68 R 2 =0.99
Figure 5. Linear fit to Langmuir isotherms for PAM adsorption at pH 8, 9 and 10 on chalcopyrite, bornite and enargite
1/qe,
g/mg
1/q, e
g/mg
1/qe,
g/mg
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Extracted Text (may have errors)

2524 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
that the interactions between PAM molecules and the sur-
faces of copper sulfides become stronger at higher pH val-
ues. Figure 3 shows that the zeta potential changes caused
by the presence of PAM are relevant at higher pH values,
however, there are no changes on the isoelectric points. This
trend aligns with the concept that at higher pH levels, the
surfaces of copper sulfides and PAM become more reac-
tive, leading to increased adsorption. Conversely, at lower
pH levels, the reactivity of both materials is reduced, which
explains the lack of changes in the IEP.
The effects of PAM molecules on chalcopyrite, enar-
gite and bornite flotation, zeta potentials, and adsorption
trends presented in Figures 2 to 4 are similarly significant
in scale. Chalcopyrite is a copper sulfide that exhibits natu-
ral hydrophobicity at low pH and under a range of redox
potential of 100–500 mV/NHE (Heyes, 1997 Leja, 1981).
The natural floatability of chalcopyrite decreases with pH
causing the potential range to narrow due to the forma-
tion of iron and copper hydroxides on the surface sites on
which anionic PAM molecules tend to adsorb causing low
recoveries. The enargite surface properties in flotation were
previously investigated (Kantar, 2002 Plackowski et al.,
2012 Guo and Yen, 2002 Yepsen et al., 2019 Yepsen and
Gutierrez, 2020). It was reported that enargite flotation is
affected by pH and pulp redox potential, i.e., collectorless
flotation is good at low pH and high Eh which is explained
0,0 0,1 0,2 0,3
1/Ce, L/mg
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
4,5
5,0
Chalcopyrite
pH 8
pH 9
pH 10
1/qe =16.8 (1/Ce) +0.15 R 2 =0.98
1/qe =9.59 (1/Ce) +0.48 R 2 =0.98
1/qe =8.67 (1/Ce) +0.43 R 2 =0.99
0,0 0,1 0,2 0,3 0,4 0,5
1/Ce, L/mg
0,0
0,5
1,0
1,5
2,0
2,5
3,0
Enargite
pH 8
pH 9
pH 10
1/qe =5.34 (1/Ce) +0.53 R 2 =0.99
1/qe =5.49 (1/Ce) +0.41 R 2 =0.98
1/qe =5.17 (1/Ce) +0.38 R 2 =0.97
0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9
1/Ce, L/mg
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
4,5
5,0
Bornite
pH 8
pH 9
pH 10
1/qe =4.82 (1/Ce) +0.61 R 2 =0.996
1/qe =2.15 (1/Ce) +0.80 R 2 =0.98
1/qe =2.03 (1/Ce) +0.68 R 2 =0.99
Figure 5. Linear fit to Langmuir isotherms for PAM adsorption at pH 8, 9 and 10 on chalcopyrite, bornite and enargite
1/qe,
g/mg
1/q, e
g/mg
1/qe,
g/mg

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