2502 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Furthermore, the S 2p XPS spectrum of galena after
the adsorption of MSA displays peaks at around 160.79eV,
161.99eV, 163.64eV, and 164.95eV. The peaks at 163.64eV
and 164.95eV are attributed to the -SH group in MSA.
Moreover, a shift of approximately 1eV in the two peaks,
compared with MSA alone, suggests a preliminary indica-
tion that metal ion Pb2+ on the galena surface may have
formed complexes with sulfur-containing groups in the
reagent. This shift implies changes in the bond energy of
the sulfur-containing atom functional group in the reagent.
Consequently, it can be inferred that the -SH group in MSA
likely reacts with Pb sites on the galena surface, leading to
the formation of complexes. These findings substantiate
that the inhibitor MSA is adsorbed on the galena surface
through the -SH group, establishing Pb-S bonds with the
Pb sites on the surface.
Figure 10(b) displays the results of O1s XPS spectra for
galena with and without MSA. The original galena exhib-
its a single peak at 531.17eV, possibly due to slight sur-
face oxidation. MSA displays two O1s peaks at 531.27eV
and 532.45eV, corresponding to C-O and C=O struc-
tures, respectively. Adsorption of MSA on the galena sur-
face results in two characteristic peaks at approximately
531.25eV and 532.21eV, representing C-O and C=O in
MSA, with minimal change in binding energy compared to
MSA. This suggests a relatively weak interaction between
oxygen atoms and Pb sites on the galena surface, indicating
that oxygen-containing groups play a limited role in the
adsorption process.
As shown in the Figure 10(c), the C 1s spectra of the
original galena only has a peak at 284.80eV, which may
be caused by the organic carbon pollution of the galena
exposed to the air. The two characteristic peaks of MSA
appear at 288.49eV and 284.80eV, among which the char-
acteristic peak at 288.49eV is caused by the O-C=O in the
molecular structure. Compared with the original galena,
two peaks are observed in the C 1s spectra of the galena
surface treated with MSA. The main peak at 284.80eV
belongs to the C 1s peak of the reference galena, and the
peak at 288.10eV is caused by the O-C=O group in the
structure of the inhibitor MSA. But compared with the
O-C=O characteristic peak in MSA, its position has not
changed significantly.
The XPS spectra of Pb 4f of galena before and after
treatment with MSA are presented in Figure 10(d). The
untreated galena surface exhibits characteristic peaks at
137.52 and 142.47eV, corresponding to Pb 4f7/2 and
Pb 4f5/2. After MSA treatment, four peaks appear on the
galena surface, with peaks at 138.72 and 143.41eV indi-
cating Pb Oxide 4f7/2 and Pb Oxide 4f5/2 due to slight
oxidation during the treatment. The original galena peaks
shift by about 0.3eV, influenced by the change in electron
density resulting from the combination of S atoms in MSA
with lead on the galena surface. The combined XPS spectra
of Pb 4f and S 2p confirm the involvement of S atoms in
MSA in the reaction with Pb sites on the galena surface,
demonstrating an inhibitory effect on galena.
Combining the molecular structure of MSA with the
analyses of XPS and UV-Vis, it can be inferred that the func-
tional group in MSA reacting with Pb sites on the galena
surface is the -C(=S)-S- group. The adsorption model is
illustrated as shown in Figure 11. As mentioned above, the
MSA structure contains a two hydrophilic groups, result-
ing in hydrophilic characteristics on the galena surface. This
arrangement serves the purpose of inhibiting galena, effec-
tively achieving the suppression of galena flotation.
CONCLUSION
This study’s pivotal contribution lies in the discovery and
application of MSA as a distinctive depressant for galena in
the flotation separation of molybdenite from galena. The
experimental analyses, encompassing both single mineral
and artificially mixed mineral flotation tests, established
MSA’s superior capability in selectively inhibiting galena.
Specifically, MSA’s application resulted in an impressive
diminution of lead recovery to 5.78%, while ensuring
that the recovery rate of molybdenum in the concentrate
remained above 90%, even at a relatively low dosage of
4.5 mg/L. This marked efficiency in Mo-Pb separation not
only outperforms Phosphorknox but also signifies a signifi-
cant advancement in the field of mineral processing.
Further empirical evidence through contact angle mea-
surements substantiates MSA’s role in selectively modifying
the floatability characteristics of galena. These measure-
ments revealed MSA’s effectiveness in engendering a selec-
tive depression of lead, while simultaneously preserving the
Figure 11. The recommended adsorption mode of MSA on
galena surface
Furthermore, the S 2p XPS spectrum of galena after
the adsorption of MSA displays peaks at around 160.79eV,
161.99eV, 163.64eV, and 164.95eV. The peaks at 163.64eV
and 164.95eV are attributed to the -SH group in MSA.
Moreover, a shift of approximately 1eV in the two peaks,
compared with MSA alone, suggests a preliminary indica-
tion that metal ion Pb2+ on the galena surface may have
formed complexes with sulfur-containing groups in the
reagent. This shift implies changes in the bond energy of
the sulfur-containing atom functional group in the reagent.
Consequently, it can be inferred that the -SH group in MSA
likely reacts with Pb sites on the galena surface, leading to
the formation of complexes. These findings substantiate
that the inhibitor MSA is adsorbed on the galena surface
through the -SH group, establishing Pb-S bonds with the
Pb sites on the surface.
Figure 10(b) displays the results of O1s XPS spectra for
galena with and without MSA. The original galena exhib-
its a single peak at 531.17eV, possibly due to slight sur-
face oxidation. MSA displays two O1s peaks at 531.27eV
and 532.45eV, corresponding to C-O and C=O struc-
tures, respectively. Adsorption of MSA on the galena sur-
face results in two characteristic peaks at approximately
531.25eV and 532.21eV, representing C-O and C=O in
MSA, with minimal change in binding energy compared to
MSA. This suggests a relatively weak interaction between
oxygen atoms and Pb sites on the galena surface, indicating
that oxygen-containing groups play a limited role in the
adsorption process.
As shown in the Figure 10(c), the C 1s spectra of the
original galena only has a peak at 284.80eV, which may
be caused by the organic carbon pollution of the galena
exposed to the air. The two characteristic peaks of MSA
appear at 288.49eV and 284.80eV, among which the char-
acteristic peak at 288.49eV is caused by the O-C=O in the
molecular structure. Compared with the original galena,
two peaks are observed in the C 1s spectra of the galena
surface treated with MSA. The main peak at 284.80eV
belongs to the C 1s peak of the reference galena, and the
peak at 288.10eV is caused by the O-C=O group in the
structure of the inhibitor MSA. But compared with the
O-C=O characteristic peak in MSA, its position has not
changed significantly.
The XPS spectra of Pb 4f of galena before and after
treatment with MSA are presented in Figure 10(d). The
untreated galena surface exhibits characteristic peaks at
137.52 and 142.47eV, corresponding to Pb 4f7/2 and
Pb 4f5/2. After MSA treatment, four peaks appear on the
galena surface, with peaks at 138.72 and 143.41eV indi-
cating Pb Oxide 4f7/2 and Pb Oxide 4f5/2 due to slight
oxidation during the treatment. The original galena peaks
shift by about 0.3eV, influenced by the change in electron
density resulting from the combination of S atoms in MSA
with lead on the galena surface. The combined XPS spectra
of Pb 4f and S 2p confirm the involvement of S atoms in
MSA in the reaction with Pb sites on the galena surface,
demonstrating an inhibitory effect on galena.
Combining the molecular structure of MSA with the
analyses of XPS and UV-Vis, it can be inferred that the func-
tional group in MSA reacting with Pb sites on the galena
surface is the -C(=S)-S- group. The adsorption model is
illustrated as shown in Figure 11. As mentioned above, the
MSA structure contains a two hydrophilic groups, result-
ing in hydrophilic characteristics on the galena surface. This
arrangement serves the purpose of inhibiting galena, effec-
tively achieving the suppression of galena flotation.
CONCLUSION
This study’s pivotal contribution lies in the discovery and
application of MSA as a distinctive depressant for galena in
the flotation separation of molybdenite from galena. The
experimental analyses, encompassing both single mineral
and artificially mixed mineral flotation tests, established
MSA’s superior capability in selectively inhibiting galena.
Specifically, MSA’s application resulted in an impressive
diminution of lead recovery to 5.78%, while ensuring
that the recovery rate of molybdenum in the concentrate
remained above 90%, even at a relatively low dosage of
4.5 mg/L. This marked efficiency in Mo-Pb separation not
only outperforms Phosphorknox but also signifies a signifi-
cant advancement in the field of mineral processing.
Further empirical evidence through contact angle mea-
surements substantiates MSA’s role in selectively modifying
the floatability characteristics of galena. These measure-
ments revealed MSA’s effectiveness in engendering a selec-
tive depression of lead, while simultaneously preserving the
Figure 11. The recommended adsorption mode of MSA on
galena surface