XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3013
included pulp filtrate as well as 5% copper sulfate solution
and 5% calcium polysulfide (CaSn, n=2–8) solution. The
Raman spectrum results are shown in Figure 5.
In the spectra of the pulp filtrate without lime, three
obvious peaks at about 180, 980 and 1640 cm−1 were dis-
tinguished in the 100–2000 cm−1 region among which,
the peaks at around 1640 and 980 cm−1 are attributed to
the symmetrical bending vibration of the water molecule
and symmetrical telescopic vibration of SO
4
2- ,respec-
tively (Pye and Rudolph, 2001 Walrafen, 1964 Zhu et al.,
2015). The peak at about 180 cm–1 was also observed in
the Raman spectrum of anion such as SO
3
2- or S O
2 3
2-
(Nicol et al., 2014 Sun et al., 2015), so it cannot be simply
attributed to one specific constituent. In the Raman spec-
trum of the pulp filtrate with lime, besides wavenumbers of
180, 980 and 1640 cm−1, pronounced peaks were found at
155, 220 and 472 cm−1, which perfectly matched the three
characteristic peak positions for polysulfides (S
n
2- ,n=2–8)
and could be attributed to the S-S vibration of S
n
2- .Similar
conclusions are reported in literature (Hagen et al., 2013
Mycroft et al., 1990 Song et al., 2020). Thus, the major
dissolved components in the pulp filtrate before and after
pyrite/pyrrhotite depression with lime included SO
4
2- ,
SO
3
2- and S O
2 3
2- ,which were produced from the dissolu-
tion of surface oxidation products of sulfide minerals such
as pyrite and pyrrhotite more notably, S
n
2- was generated
in a strongly alkaline pulp system with lime, and this phe-
nomenon was not found in the pulp filtrate without lime.
The dominant role of Eh regulation in Zn-S selective
flotation was demonstrated. To understand the influence
of Eh on the dissolved components in the pulp, the pulp
filtrate with adding lime and then regulating Eh by aera-
tion or not was performed by Raman spectrum (Figure 6).
As illustrated in Figure 6A-C, for the sample without Eh
0 min 1min 2min 3min 4min 8min
0
5
10
15
20
25
30
Grade
Recovery
Aeration time (min)
0
10
20
30
40
50
60
70
80
90
100
A
0 min 1min 2min 3min 4min 8min
0
10
20
30
40
50
60
Aeration time (min)
Grade
Recovery
B
0
10
20
30
40
50
60
70
80
90
100
0 min 1min 2min 3min 4min 8min
-350
-300
-250
-200
-150
-100
-50
0
50
100
C
Aeration time (min)
Figure 4. The change of Eh with aeration time in the process of pyrite/pyrrhotite depression with lime and the corresponding
flotation results. Permission from Li et al. (2023a)
Zn
grade
(%)
Zn
recovery
(%)
S
grade
(%)
S
recovery
(%)
Pulp
potential
(mv
vs.
SHE)
included pulp filtrate as well as 5% copper sulfate solution
and 5% calcium polysulfide (CaSn, n=2–8) solution. The
Raman spectrum results are shown in Figure 5.
In the spectra of the pulp filtrate without lime, three
obvious peaks at about 180, 980 and 1640 cm−1 were dis-
tinguished in the 100–2000 cm−1 region among which,
the peaks at around 1640 and 980 cm−1 are attributed to
the symmetrical bending vibration of the water molecule
and symmetrical telescopic vibration of SO
4
2- ,respec-
tively (Pye and Rudolph, 2001 Walrafen, 1964 Zhu et al.,
2015). The peak at about 180 cm–1 was also observed in
the Raman spectrum of anion such as SO
3
2- or S O
2 3
2-
(Nicol et al., 2014 Sun et al., 2015), so it cannot be simply
attributed to one specific constituent. In the Raman spec-
trum of the pulp filtrate with lime, besides wavenumbers of
180, 980 and 1640 cm−1, pronounced peaks were found at
155, 220 and 472 cm−1, which perfectly matched the three
characteristic peak positions for polysulfides (S
n
2- ,n=2–8)
and could be attributed to the S-S vibration of S
n
2- .Similar
conclusions are reported in literature (Hagen et al., 2013
Mycroft et al., 1990 Song et al., 2020). Thus, the major
dissolved components in the pulp filtrate before and after
pyrite/pyrrhotite depression with lime included SO
4
2- ,
SO
3
2- and S O
2 3
2- ,which were produced from the dissolu-
tion of surface oxidation products of sulfide minerals such
as pyrite and pyrrhotite more notably, S
n
2- was generated
in a strongly alkaline pulp system with lime, and this phe-
nomenon was not found in the pulp filtrate without lime.
The dominant role of Eh regulation in Zn-S selective
flotation was demonstrated. To understand the influence
of Eh on the dissolved components in the pulp, the pulp
filtrate with adding lime and then regulating Eh by aera-
tion or not was performed by Raman spectrum (Figure 6).
As illustrated in Figure 6A-C, for the sample without Eh
0 min 1min 2min 3min 4min 8min
0
5
10
15
20
25
30
Grade
Recovery
Aeration time (min)
0
10
20
30
40
50
60
70
80
90
100
A
0 min 1min 2min 3min 4min 8min
0
10
20
30
40
50
60
Aeration time (min)
Grade
Recovery
B
0
10
20
30
40
50
60
70
80
90
100
0 min 1min 2min 3min 4min 8min
-350
-300
-250
-200
-150
-100
-50
0
50
100
C
Aeration time (min)
Figure 4. The change of Eh with aeration time in the process of pyrite/pyrrhotite depression with lime and the corresponding
flotation results. Permission from Li et al. (2023a)
Zn
grade
(%)
Zn
recovery
(%)
S
grade
(%)
S
recovery
(%)
Pulp
potential
(mv
vs.
SHE)