1904 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
CONCLUSION
This study investigated the sulfide oxidation and gold disso-
lution of a refractory gold-molybdenum concentrate using
hypochlorite solution. The two-stage hypochlorite leaching
involves sulfide oxidation by hypochlorite ions in the first
stage and gold dissolution by hypochlorous acid in the sec-
ond stage as indicated by the solution Eh and pH. After
the 1st stage, gold dissolution of 55% is attained possibly
from the free, exposed and associated gold that is dissolved.
Molybdenum dissolution of 88.54% is also achieved indi-
cating that molybdenite oxidation by hypochlorite also
occurs and hypochlorite solution can be used to dissolve
molybdenum from the concentrate. Gold dissolution of
93.51% is achieved at the end of leaching. Remaining
gold that is not dissolved could have been gold locked in
silicates that are not dissolved by hypochlorite. Based on
the shrinking-core model, rate determining step for sulfide
oxidation is diffusion control with an amorphous oxide
formed as outer layer. The promising gold and molybde-
num dissolution show that the use of hypochlorite solution
can be a potential eco-friendly and more simplified alter-
native for gold extraction of refractory gold-molybdenum
concentrates.
REFERENCES
Ahtiainen, R., Liipo, J., &Lundström, M. (2021).
Simultaneous sulfide oxidation and gold dissolution
by cyanide-free leaching from refractory and double
refractory gold concentrates. Minerals Engineering,
170. doi: 10.1016/j.mineng.2021.107042.
Azizitorghabeh, A., Mahandra, H., Ramsay, J., &
Ghahreman, A. (2022). A sustainable approach for gold
recovery from refractory source using novel BIOX-TC
system. Journal of Industrial and Engineering
Chemistry. doi: 10.1016/j.jiec.2022.08.002.
Cao, Z. fang, Zhong, H., Qiu, Z. hui, Liu, G. yi, &
Zhang, W. xuan. (2009). A novel technology for
molybdenum extraction from molybdenite concen-
trate. Hydrometallurgy, 99(1–2), 2–6. doi: 10.1016
/j.hydromet.2009.05.001.
Chandra, A. P., &Gerson, A. R. (2010). The mechanisms
of pyrite oxidation and leaching: A fundamental per-
spective. In Surface Science Reports (Vol. 65, Issue 9,
pp. 293–315). doi: 10.1016/j.surfrep.2010.08.003.
Chung, K. W., Yoon, H. S., Kim, C. J., &Jeon, H. S.
(2021). Selective leaching of molybdenum from bulk
concentrate by electro-oxidation. Metals, 11(12). doi:
10.3390/met11121904.
Dos Santos, E. C., De Mendonça Silva, J. C., &Duarte, H.
A. (2016). Pyrite Oxidation Mechanism by Oxygen in
Aqueous Medium. Journal of Physical Chemistry C,
120(5), 2760–2768. doi: 10.1021/acs.jpcc.5b10949.
Hasab, M. G., Rashchi, F., &Raygan, S. (2013).
Simultaneous sulfide oxidation and gold leaching of a
refractory gold concentrate by chloride–hypochlorite
solution. Minerals Engineering, 50–51, 140–142. doi:
10.1016/j.mineng.2012.08.011.
Hasab, M. G., Raygan, S., &Rashchi, F. (2013). Chloride-
hypochlorite leaching of gold from a mechanically acti-
vated refractory sulfide concentrate. Hydrometallurgy,
138, 59–64. doi: 10.1016/j.hydromet.2013.06.013.
Hesami, R., Ahmadi, A., Raouf Hosseini, M., &Manafi, Z.
(2022). Electroleaching kinetics of molybdenite con-
centrate of Sarcheshmeh copper complex in chlo-
ride media. Minerals Engineering, 186. doi: 10.1016
/j.mineng.2022.107721.
Li, J., Kou, J., Sun, C., Zhang, N., &Zhang, H. (2023).
A review of environmentally friendly gold lixiviants:
Fundamentals, applications, and commonalities. In
Minerals Engineering (Vol. 197). Elsevier Ltd. doi:
10.1016/j.mineng.2023.108074.
Figure 5. XRD pattern of sulfide oxidation residue
CONCLUSION
This study investigated the sulfide oxidation and gold disso-
lution of a refractory gold-molybdenum concentrate using
hypochlorite solution. The two-stage hypochlorite leaching
involves sulfide oxidation by hypochlorite ions in the first
stage and gold dissolution by hypochlorous acid in the sec-
ond stage as indicated by the solution Eh and pH. After
the 1st stage, gold dissolution of 55% is attained possibly
from the free, exposed and associated gold that is dissolved.
Molybdenum dissolution of 88.54% is also achieved indi-
cating that molybdenite oxidation by hypochlorite also
occurs and hypochlorite solution can be used to dissolve
molybdenum from the concentrate. Gold dissolution of
93.51% is achieved at the end of leaching. Remaining
gold that is not dissolved could have been gold locked in
silicates that are not dissolved by hypochlorite. Based on
the shrinking-core model, rate determining step for sulfide
oxidation is diffusion control with an amorphous oxide
formed as outer layer. The promising gold and molybde-
num dissolution show that the use of hypochlorite solution
can be a potential eco-friendly and more simplified alter-
native for gold extraction of refractory gold-molybdenum
concentrates.
REFERENCES
Ahtiainen, R., Liipo, J., &Lundström, M. (2021).
Simultaneous sulfide oxidation and gold dissolution
by cyanide-free leaching from refractory and double
refractory gold concentrates. Minerals Engineering,
170. doi: 10.1016/j.mineng.2021.107042.
Azizitorghabeh, A., Mahandra, H., Ramsay, J., &
Ghahreman, A. (2022). A sustainable approach for gold
recovery from refractory source using novel BIOX-TC
system. Journal of Industrial and Engineering
Chemistry. doi: 10.1016/j.jiec.2022.08.002.
Cao, Z. fang, Zhong, H., Qiu, Z. hui, Liu, G. yi, &
Zhang, W. xuan. (2009). A novel technology for
molybdenum extraction from molybdenite concen-
trate. Hydrometallurgy, 99(1–2), 2–6. doi: 10.1016
/j.hydromet.2009.05.001.
Chandra, A. P., &Gerson, A. R. (2010). The mechanisms
of pyrite oxidation and leaching: A fundamental per-
spective. In Surface Science Reports (Vol. 65, Issue 9,
pp. 293–315). doi: 10.1016/j.surfrep.2010.08.003.
Chung, K. W., Yoon, H. S., Kim, C. J., &Jeon, H. S.
(2021). Selective leaching of molybdenum from bulk
concentrate by electro-oxidation. Metals, 11(12). doi:
10.3390/met11121904.
Dos Santos, E. C., De Mendonça Silva, J. C., &Duarte, H.
A. (2016). Pyrite Oxidation Mechanism by Oxygen in
Aqueous Medium. Journal of Physical Chemistry C,
120(5), 2760–2768. doi: 10.1021/acs.jpcc.5b10949.
Hasab, M. G., Rashchi, F., &Raygan, S. (2013).
Simultaneous sulfide oxidation and gold leaching of a
refractory gold concentrate by chloride–hypochlorite
solution. Minerals Engineering, 50–51, 140–142. doi:
10.1016/j.mineng.2012.08.011.
Hasab, M. G., Raygan, S., &Rashchi, F. (2013). Chloride-
hypochlorite leaching of gold from a mechanically acti-
vated refractory sulfide concentrate. Hydrometallurgy,
138, 59–64. doi: 10.1016/j.hydromet.2013.06.013.
Hesami, R., Ahmadi, A., Raouf Hosseini, M., &Manafi, Z.
(2022). Electroleaching kinetics of molybdenite con-
centrate of Sarcheshmeh copper complex in chlo-
ride media. Minerals Engineering, 186. doi: 10.1016
/j.mineng.2022.107721.
Li, J., Kou, J., Sun, C., Zhang, N., &Zhang, H. (2023).
A review of environmentally friendly gold lixiviants:
Fundamentals, applications, and commonalities. In
Minerals Engineering (Vol. 197). Elsevier Ltd. doi:
10.1016/j.mineng.2023.108074.
Figure 5. XRD pattern of sulfide oxidation residue