XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1753
under which arsenopyrite is completely coated with FePO4
precipitates.
Effect of FePO4 Coating on the Leachability of
Arsenopyrite
After extracting gold from arsenopyritic ores, leach residue
containing high content of arsenopyrite will be disposed
of at a landfill site. When this leach residue is exposed to
atmospheric conditions, arsenopyrite is oxidized, resulting
in the formation of acid mine drainage (AMD) as well as
the release of toxic arsenic into the environment (Park et
al., 2019). The previous study of the authors investigated
the effect of FePO4 coating on the leachability of arseno-
pyrite (Park et al., 2021). Figure 6 shows the dissolved As
concentrations released from uncoated and FePO4-coated
arsenopyrite after leaching with DI water for 24 h. As can
be seen, ~0.36 mM of As was leached out from uncoated
arsenopyrite, while arsenic release was limited to ~0.09
mM in the case of FePO4-coated arsenopyrite (Figure 6).
This result implies that the application of ME treatment
can not only improve the efficiency of thiosulfate leaching
in extracting gold from arsenopyritic ores but also reduce
arsenic release from leach residues.
CONCLUSIONS
This study investigated the applicability of ME treatment
to improve the efficiency of gold extraction from a simu-
lated gold-bearing arsenopyrite ores by thiosulfate leaching.
The findings of this study are summarized as follows:
1. Arsenopyrite enhanced the decomposition of thio-
sulfate, and as a result, gold extraction decreased
from 99% to ~10%.
2. Microencapsulation using ferrous and phosphate
ions could create FePO4 coating on the surface of
arsenopyrite.
3. The application of ME treatment prior to thio-
sulfate leaching improved the efficiency of gold
extraction from ~10% to 52%, and moreover, arse-
nopyrite oxidation releasing toxic arsenic into the
environment was suppressed after ME treatment.
4. After ME treatment under the studied condition,
the surface of arsenopyrite was not completely
passivated, and thus gold extraction was limited
to ~52%. Therefore, further study is necessary to
improve the efficiency of gold extraction by opti-
mizing ME treatment conditions.
REFERENCES
Aylmore, M.G., 2005. Alternative lixiviants to cyanide for
leaching gold ores. Developments in Mineral Processing
15: 501–539.
Energy Industry Review, 2018. Gold’s role in improving
energy efficiency and developing low carbon technolo-
gies. https://energyindustryreview.com/metals-mining
/golds-role-in-improving-energy-efficiency-and
-developing-low-carbon-technologies. Accessed 15th
Jan 2024.
Figure 5. The effect of microencapsulation treatment on the
extraction of gold by thiosulfate leaching in the presence of
arsenopyrite
Figure 6. Dissolved As concentration released from untreated
and ME-treated arsenopyrite (Park et al., 2021)
under which arsenopyrite is completely coated with FePO4
precipitates.
Effect of FePO4 Coating on the Leachability of
Arsenopyrite
After extracting gold from arsenopyritic ores, leach residue
containing high content of arsenopyrite will be disposed
of at a landfill site. When this leach residue is exposed to
atmospheric conditions, arsenopyrite is oxidized, resulting
in the formation of acid mine drainage (AMD) as well as
the release of toxic arsenic into the environment (Park et
al., 2019). The previous study of the authors investigated
the effect of FePO4 coating on the leachability of arseno-
pyrite (Park et al., 2021). Figure 6 shows the dissolved As
concentrations released from uncoated and FePO4-coated
arsenopyrite after leaching with DI water for 24 h. As can
be seen, ~0.36 mM of As was leached out from uncoated
arsenopyrite, while arsenic release was limited to ~0.09
mM in the case of FePO4-coated arsenopyrite (Figure 6).
This result implies that the application of ME treatment
can not only improve the efficiency of thiosulfate leaching
in extracting gold from arsenopyritic ores but also reduce
arsenic release from leach residues.
CONCLUSIONS
This study investigated the applicability of ME treatment
to improve the efficiency of gold extraction from a simu-
lated gold-bearing arsenopyrite ores by thiosulfate leaching.
The findings of this study are summarized as follows:
1. Arsenopyrite enhanced the decomposition of thio-
sulfate, and as a result, gold extraction decreased
from 99% to ~10%.
2. Microencapsulation using ferrous and phosphate
ions could create FePO4 coating on the surface of
arsenopyrite.
3. The application of ME treatment prior to thio-
sulfate leaching improved the efficiency of gold
extraction from ~10% to 52%, and moreover, arse-
nopyrite oxidation releasing toxic arsenic into the
environment was suppressed after ME treatment.
4. After ME treatment under the studied condition,
the surface of arsenopyrite was not completely
passivated, and thus gold extraction was limited
to ~52%. Therefore, further study is necessary to
improve the efficiency of gold extraction by opti-
mizing ME treatment conditions.
REFERENCES
Aylmore, M.G., 2005. Alternative lixiviants to cyanide for
leaching gold ores. Developments in Mineral Processing
15: 501–539.
Energy Industry Review, 2018. Gold’s role in improving
energy efficiency and developing low carbon technolo-
gies. https://energyindustryreview.com/metals-mining
/golds-role-in-improving-energy-efficiency-and
-developing-low-carbon-technologies. Accessed 15th
Jan 2024.
Figure 5. The effect of microencapsulation treatment on the
extraction of gold by thiosulfate leaching in the presence of
arsenopyrite
Figure 6. Dissolved As concentration released from untreated
and ME-treated arsenopyrite (Park et al., 2021)