2184 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
(slight decrease in adsorption with increasing pH), in the
case of SS-PAM, an increase in pH increases the adsorp-
tion of the reagent. In this way, it could be established that
this greater adsorption is a product of greater interaction
between both, however, this phenomenon generates an
excessive coating of the surface of the particles, causing a
significant decrease in their hydrophobicity. This hypoth-
esis will be verified in subsequent stages of the experimental
program of this research.
On the other hand, it is important to compare the effect
of flocculant degradation. First, it is reasonable to expect a
decrease in the size of PAM molecules as their degradation
increases. Based on the above, it can be established that less
adsorption of MS and SS-PAM is needed to generate sig-
nificant impacts on the recovery of chalcopyrite, compared
to what occurs with SS-PAM. In this case, since its mol-
ecules are smaller, greater adsorption is required to cover
the surface of the particles. This trend is corroborated both
with flotation tests and with induction time measurements.
CONCLUSIONS
From the experimental tests developed up to this stage of
the research, it is possible to conclude that both the pH
and the degradation of the flocculant are very important
variables to consider when evaluating the recovery by flo-
tation of chalcopyrite in the presence of PAM as residual
flocculant in recirculated process water. In general, between
pH values of 7 and 9, no major differences were seen in
the results obtained, however, at pH 11 the trends changed
completely, especially for the highest degradation condi-
tion (SS-PAM). Microflotation tests showed that chalco-
pyrite recovery is strongly affected in the presence of PAM.
At low pH values the most significant depressant effect is
induced by NS-PAM, while at pH 11 it is the presence
of SS-PAM that most decreased the recovery of chalcopy-
rite, for any evaluated dosage of flocculant. Induction time
measurements indicated that when the recovery of chal-
copyrite decreased, the hydrophobicity of these particles
also decreased. This suggests that PAM, independent of its
degree of degradation, generates a hydrophilic coating on
the surface of the chalcopyrite. Regarding the results for the
adsorption of PAM, it is possible to establish that for NS
and MS-PAM there is a relationship inversely proportional
to pH, although the variations are negligible. On the other
hand, for SS-PAM there is a directly proportional relation-
ship between its adsorption on chalcopyrite and the pH.
The condition in which there is greater adsorption and a
greater impact on both chalcopyrite recovery and induc-
tion time is at pH 11. A possible explanation for this phe-
nomenon is that due to the greater ionic strength of the
solution at this pH value, the different compounds pres-
ent in the PAM molecules, mostly anionic, interact more
actively with the metal cations present on the surface of
the chalcopyrite. In this way, a hydrophilic coating would
be generated that almost completely prevents the flotation
of the copper mineral. The interactions that occur under
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 10 20 30 40 50
PAM equilibrium concentration, mg/L
NS-PAM
MS-PAM
SS-PAM
Figure 9. PAM adsorption on chalcopyrite particles as a function of PAM concentration for the
different levels of mechanical degradation evaluated (NS, MS and SS-PAM) at pH 11 using a 0.01
M NaCl solution
PAM
adsorption,
mg/g
(slight decrease in adsorption with increasing pH), in the
case of SS-PAM, an increase in pH increases the adsorp-
tion of the reagent. In this way, it could be established that
this greater adsorption is a product of greater interaction
between both, however, this phenomenon generates an
excessive coating of the surface of the particles, causing a
significant decrease in their hydrophobicity. This hypoth-
esis will be verified in subsequent stages of the experimental
program of this research.
On the other hand, it is important to compare the effect
of flocculant degradation. First, it is reasonable to expect a
decrease in the size of PAM molecules as their degradation
increases. Based on the above, it can be established that less
adsorption of MS and SS-PAM is needed to generate sig-
nificant impacts on the recovery of chalcopyrite, compared
to what occurs with SS-PAM. In this case, since its mol-
ecules are smaller, greater adsorption is required to cover
the surface of the particles. This trend is corroborated both
with flotation tests and with induction time measurements.
CONCLUSIONS
From the experimental tests developed up to this stage of
the research, it is possible to conclude that both the pH
and the degradation of the flocculant are very important
variables to consider when evaluating the recovery by flo-
tation of chalcopyrite in the presence of PAM as residual
flocculant in recirculated process water. In general, between
pH values of 7 and 9, no major differences were seen in
the results obtained, however, at pH 11 the trends changed
completely, especially for the highest degradation condi-
tion (SS-PAM). Microflotation tests showed that chalco-
pyrite recovery is strongly affected in the presence of PAM.
At low pH values the most significant depressant effect is
induced by NS-PAM, while at pH 11 it is the presence
of SS-PAM that most decreased the recovery of chalcopy-
rite, for any evaluated dosage of flocculant. Induction time
measurements indicated that when the recovery of chal-
copyrite decreased, the hydrophobicity of these particles
also decreased. This suggests that PAM, independent of its
degree of degradation, generates a hydrophilic coating on
the surface of the chalcopyrite. Regarding the results for the
adsorption of PAM, it is possible to establish that for NS
and MS-PAM there is a relationship inversely proportional
to pH, although the variations are negligible. On the other
hand, for SS-PAM there is a directly proportional relation-
ship between its adsorption on chalcopyrite and the pH.
The condition in which there is greater adsorption and a
greater impact on both chalcopyrite recovery and induc-
tion time is at pH 11. A possible explanation for this phe-
nomenon is that due to the greater ionic strength of the
solution at this pH value, the different compounds pres-
ent in the PAM molecules, mostly anionic, interact more
actively with the metal cations present on the surface of
the chalcopyrite. In this way, a hydrophilic coating would
be generated that almost completely prevents the flotation
of the copper mineral. The interactions that occur under
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 10 20 30 40 50
PAM equilibrium concentration, mg/L
NS-PAM
MS-PAM
SS-PAM
Figure 9. PAM adsorption on chalcopyrite particles as a function of PAM concentration for the
different levels of mechanical degradation evaluated (NS, MS and SS-PAM) at pH 11 using a 0.01
M NaCl solution
PAM
adsorption,
mg/g