XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3007
activation of ZnS could be evaluated using the measured
values of Pb2+ and Zn2+ (El-Shall 2000). The changes in
free energy (ΔG) were calculated using measured values of
Pb2+ and Zn2+ concentrations and the equilibrium con-
stant (K=1000, El-Shall 2000).
ln ln^Zn G K /Pb 2 2+ =-RT ++h
K
K
K
sp
PbS
sp
ZnS
=
The calculated results of the changes in free energy with-
out the pretreatment was negative while those with pre-
treatments using CH3COONH4 or NaCl-HCl were
positive. When the change in free energy is positive, the
reverse reaction of lead activation would occur spontane-
ously, indicating that lead activation would be limited by
the pretreatment. These results support the finding that the
effective depression of ZnS floatability was achieved by the
pretreatments which decreased Pb2+ concentration during
flotation by extracting PbSO4 in advance (Table 1).
CONCLUSIONS
In this study, pretreatments of flotation feed materials using
CH3COONH4 or NaCl to extract PbSO4 for prevention
of lead pollution the surrounding environment of tailings
dam and depression of ZnS floatability combined with
recovery of extracted Pb2+ by cementation or CEC was
investigated, and the findings of this study are summarized
as follows:
• Almost of all PbSO4 (99%) was extracted using
CH3COONH4, and 99% of extracted Pb2+ could
be recovered as Pb0 by cementation using ZVI.
• Almost of all PbSO4 (97%) was extracted and
recovered on ZVI as Pb0 by the coupled extraction-
cementation method using NaCl-HCl as an extract-
ant of PbSO4 and ZVI as a reductant.
• Pretreatments of flotation extracting PbSO4
using CH3COONH4 or NaCl-HCl were effec-
tive in depressing ZnS floatability, indicating that
CH3COONH4 and NaCl-HCl could be used
instead of EDTA for the extraction of PbSO4 to
depress the floatability of ZnS.
ACKNOWLEDGMENT
This work was financially supported by JSPS KAKENHI
Grant Number JP21J20552 and 22KJ0015.
REFERENCES
Aikawa, K., Ito, M., Kusano, A. et al. 2022. Development
of a Sustainable Process for Complex Sulfide Ores
Containing Anglesite: Effect of Anglesite on Sphalerite
Floatability, Enhanced Depression of Sphalerite by
Extracting Anglesite, and Recovery of Extracted Pb2+
as Zero-Valent Pb by Cementation Using Zero-Valent
Fe. Minerals, 12(6): 723.
Aikawa, K., Ito, M., Kusano, A. et al. 2021. Flotation
of Seafloor Massive Sulfide Ores: Combination of
Surface Cleaning and Deactivation of Lead-Activated
Sphalerite to Improve the Separation Efficiency of
Chalcopyrite and Sphalerite. Metals, 11(2): 253.
Aikawa, K., Ito, M., Segawa, T. et al. 2020. Depression of
lead-activated sphalerite by pyrite via galvanic interac-
tions: Implications to the selective flotation of complex
sulfide ores. Minerals Engineering, 152: 106367.
Figure 4. Effects of pretreatments using CH3COONH4
or NaCl on the floatability of ZnS in the presence of
PbSO4: (a) W/o pretreatments, (b) w/ a pretreatment using
CH3COONH4, and (c) w/ a pretreatment using NaCl-HCl
Table 1. Calculated results of the change in free energy (ΔG)
without pretreatments or with CH3COONH4 or NaCl-HCl
pretreatment
ΔG (kJ/mol)
without
pretreatments
ΔG (kJ/mol)
with CH3COONH4
pretreatment
ΔG (kJ/mol)
with NaCl
pretreatment
–5.9 3.1 1.2
activation of ZnS could be evaluated using the measured
values of Pb2+ and Zn2+ (El-Shall 2000). The changes in
free energy (ΔG) were calculated using measured values of
Pb2+ and Zn2+ concentrations and the equilibrium con-
stant (K=1000, El-Shall 2000).
ln ln^Zn G K /Pb 2 2+ =-RT ++h
K
K
K
sp
PbS
sp
ZnS
=
The calculated results of the changes in free energy with-
out the pretreatment was negative while those with pre-
treatments using CH3COONH4 or NaCl-HCl were
positive. When the change in free energy is positive, the
reverse reaction of lead activation would occur spontane-
ously, indicating that lead activation would be limited by
the pretreatment. These results support the finding that the
effective depression of ZnS floatability was achieved by the
pretreatments which decreased Pb2+ concentration during
flotation by extracting PbSO4 in advance (Table 1).
CONCLUSIONS
In this study, pretreatments of flotation feed materials using
CH3COONH4 or NaCl to extract PbSO4 for prevention
of lead pollution the surrounding environment of tailings
dam and depression of ZnS floatability combined with
recovery of extracted Pb2+ by cementation or CEC was
investigated, and the findings of this study are summarized
as follows:
• Almost of all PbSO4 (99%) was extracted using
CH3COONH4, and 99% of extracted Pb2+ could
be recovered as Pb0 by cementation using ZVI.
• Almost of all PbSO4 (97%) was extracted and
recovered on ZVI as Pb0 by the coupled extraction-
cementation method using NaCl-HCl as an extract-
ant of PbSO4 and ZVI as a reductant.
• Pretreatments of flotation extracting PbSO4
using CH3COONH4 or NaCl-HCl were effec-
tive in depressing ZnS floatability, indicating that
CH3COONH4 and NaCl-HCl could be used
instead of EDTA for the extraction of PbSO4 to
depress the floatability of ZnS.
ACKNOWLEDGMENT
This work was financially supported by JSPS KAKENHI
Grant Number JP21J20552 and 22KJ0015.
REFERENCES
Aikawa, K., Ito, M., Kusano, A. et al. 2022. Development
of a Sustainable Process for Complex Sulfide Ores
Containing Anglesite: Effect of Anglesite on Sphalerite
Floatability, Enhanced Depression of Sphalerite by
Extracting Anglesite, and Recovery of Extracted Pb2+
as Zero-Valent Pb by Cementation Using Zero-Valent
Fe. Minerals, 12(6): 723.
Aikawa, K., Ito, M., Kusano, A. et al. 2021. Flotation
of Seafloor Massive Sulfide Ores: Combination of
Surface Cleaning and Deactivation of Lead-Activated
Sphalerite to Improve the Separation Efficiency of
Chalcopyrite and Sphalerite. Metals, 11(2): 253.
Aikawa, K., Ito, M., Segawa, T. et al. 2020. Depression of
lead-activated sphalerite by pyrite via galvanic interac-
tions: Implications to the selective flotation of complex
sulfide ores. Minerals Engineering, 152: 106367.
Figure 4. Effects of pretreatments using CH3COONH4
or NaCl on the floatability of ZnS in the presence of
PbSO4: (a) W/o pretreatments, (b) w/ a pretreatment using
CH3COONH4, and (c) w/ a pretreatment using NaCl-HCl
Table 1. Calculated results of the change in free energy (ΔG)
without pretreatments or with CH3COONH4 or NaCl-HCl
pretreatment
ΔG (kJ/mol)
without
pretreatments
ΔG (kJ/mol)
with CH3COONH4
pretreatment
ΔG (kJ/mol)
with NaCl
pretreatment
–5.9 3.1 1.2