1480 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
mill. The concentrate samples were re-ground with a labo-
ratory Vertimill containing ceramic media to a target grind
size P80 of 25 µm prior to leaching.
It is important to note that the leach tests were con-
ducted on the pyrite concentrate while other analysis such
as the gold-rob #and mineralogical analyses presented in
the following sections were conducted on head samples. A
carbon depressant was utilize for CM grades above 0.05%
during the flotation stages, with about 20% of the CM
reporting to the pyrite concentrate. Given the mass pull and
recovery of the flotation stages, no enrichment of the CM
was observed, therefore it was assumed that the CM pres-
ent in the pyrite concentrate samples is representative of the
CM present in the head samples, as seen in Figure 3. The
degree of particle size reduction from the original sample
to the pyrite concentrate, represents one of the limitations
for a comprehensive mineral characterization of the leach
feed samples. Particularly, sample preparation for spectros-
copy based methods can be difficult due to the fine-grained
nature of the pyrite concentrate.
Two rounds of cyanidation leach testwork were com-
pleted on 83 pyrite concentrate samples to determine the
leachable gold content that remained in concentrate gen-
erated from the sequential rougher flotation tests. Leach
testwork for all samples was completed with and without
the presence of activated carbon to assess the impact of the
carbon-in-leach (CIL) process on the gold extractions and
its ability to overcome the gold robbing produced by the
presence of CM in the samples.
Analysis of the results of the tests on both leach con-
figurations, did not show a strong correlation between the
gold recoveries and the CM content or the gold-rob #,indi-
cating that other factors are influencing the metallurgical
response. Gold robbing by various sulfides minerals as well
as clays has been reported in the literature (Miller, Wan and
Diaz 2016), given that the leach feed samples considered in
this study have variable concentration of sulfides, this could
be a factor affecting the extent of gold extraction.
To reduce the impact of other factors on the analysis of
the leach response and how it depends on the CM content,
the difference between CIL tests and leach without carbon
was examined. The delta gold extractions were calculated
using both leach tests for each sample. Figure 4 shows the
delta gold extractions plotted against the CM concentra-
tion of the pyrite concentrate samples with a dotted vertical
Figure 2. High level flowsheet of sequential rougher flotation
Figure 3. Percent of CM in the head samples vs the pyrite concentrate
mill. The concentrate samples were re-ground with a labo-
ratory Vertimill containing ceramic media to a target grind
size P80 of 25 µm prior to leaching.
It is important to note that the leach tests were con-
ducted on the pyrite concentrate while other analysis such
as the gold-rob #and mineralogical analyses presented in
the following sections were conducted on head samples. A
carbon depressant was utilize for CM grades above 0.05%
during the flotation stages, with about 20% of the CM
reporting to the pyrite concentrate. Given the mass pull and
recovery of the flotation stages, no enrichment of the CM
was observed, therefore it was assumed that the CM pres-
ent in the pyrite concentrate samples is representative of the
CM present in the head samples, as seen in Figure 3. The
degree of particle size reduction from the original sample
to the pyrite concentrate, represents one of the limitations
for a comprehensive mineral characterization of the leach
feed samples. Particularly, sample preparation for spectros-
copy based methods can be difficult due to the fine-grained
nature of the pyrite concentrate.
Two rounds of cyanidation leach testwork were com-
pleted on 83 pyrite concentrate samples to determine the
leachable gold content that remained in concentrate gen-
erated from the sequential rougher flotation tests. Leach
testwork for all samples was completed with and without
the presence of activated carbon to assess the impact of the
carbon-in-leach (CIL) process on the gold extractions and
its ability to overcome the gold robbing produced by the
presence of CM in the samples.
Analysis of the results of the tests on both leach con-
figurations, did not show a strong correlation between the
gold recoveries and the CM content or the gold-rob #,indi-
cating that other factors are influencing the metallurgical
response. Gold robbing by various sulfides minerals as well
as clays has been reported in the literature (Miller, Wan and
Diaz 2016), given that the leach feed samples considered in
this study have variable concentration of sulfides, this could
be a factor affecting the extent of gold extraction.
To reduce the impact of other factors on the analysis of
the leach response and how it depends on the CM content,
the difference between CIL tests and leach without carbon
was examined. The delta gold extractions were calculated
using both leach tests for each sample. Figure 4 shows the
delta gold extractions plotted against the CM concentra-
tion of the pyrite concentrate samples with a dotted vertical
Figure 2. High level flowsheet of sequential rougher flotation
Figure 3. Percent of CM in the head samples vs the pyrite concentrate