XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1385
inclusions (average grain size 2µm –4µm) mostly within
arsenopyrite and pyrite in the concentrate and within sili-
cates and pyrite in the tailings (Plate 6). No visible gold
grains were noted in the CIL Leach stream samples for the
double refractory ores.
Invisible Gold (Sub-Microscopic Gold) Mineralogy
Concentration of invisible gold in sulfides, Fe-Oxides and
TCM was carried out using a Cameca IMS 3F SIMS instru-
ment. Different morphological types of pyrites (coarse,
fine, porous, aggregates of microcrystalline/ disseminated
pyrite) and TCM (coarse/medium grained TCM and fine
disseminated and composite TCM) were identified by opti-
cal microscopic study and dynamic SIMS analysis was car-
ried out for each of the varieties to quantify the invisible
gold concentration.
Dynamic SIMS analysis data indicated 11% invisible
gold in Cu-Au refractory ore (Table 4a) which was con-
tributed from Fe-Oxides (6%), pyrite (2.5%) and copper
sulfides (2.5%). In double refractory and triple refractory
ore, pyrite was the dominant gold carrier accounting for
94% and 88% of total gold respectively (Table 4b and
4c). In process stream samples from the Cu-Au refractory
ore, chalcopyrite was the main invisible gold carrier and
accounted for 4.5% of total Au in the Final Concentrate.
In the cleaner scavenger tail, Fe-Oxides and pyrite were
the main invisible gold carriers accounting for 12% and
9% of total Au respectively. In the rougher tail, Fe-Oxides
accounted for 22% of total Au (Table 4a). In process stream
samples from the double refractory ore, pyrite was a mod-
erate gold carrier accounting for 23% of total gold in the
POX/CIL residue and 28% in the CIL residue (Table 4b).
In process stream samples from the triple refractory ore,
pyrite was the dominant gold carrier accounting for 85% of
total gold in the pyrite scavenger rougher concentrate and
76% in the TCM rougher concentrate (Table 4c).
Preg-Robbed Surface Gold Mineralogy in TCM
In double refractory gold ore samples, high variability in
gold-robbed surface gold largely due to the amount of
Table 3a. Modal data used for gold deportment from copper-
gold ore samples
Mineral Mass,
wt%
Sample ID
Rougher
Feed
Rougher
Tails
Cleaner
Tails
Rougher
Conc.
Chalcopyrite 1.8 0.1 0.1 85.4
Other Cu-Sulfides 0.2 0.0 0.0 7.1
Pyrite 4.3 0.6 22.6 6.3
Other Sulphides 0.2 0.0 2.5 0.2
Quartz 38.9 41.8 20.8 0.1
Plagioclase 14.5 16.6 8.8 0.0
K-Feldspar 3.4 3.8 0.9 0.0
Micas 23.7 25.0 25.6 0.3
Chlorite 5.0 5.1 4.6 0.1
Clay Minerals 3.3 2.9 5.3 0.1
Anhydrite/Gypsum 1.9 1.4 5.7 0.0
Fe- Oxides 1.6 1.7 0.4 0.0
Other* 1.0 1.0 3.0 0.0
Total 100 100 100 100
*including amphibole, apatite, carbonates and ilmenite/rutile
Table 3b. Modal data used for gold deportment from double
refractory ore
Mineral Mass, wt%
Sample ID
Feed
POX/CIL
Residue
CIL
Residue
Quartz 51.1 52.0 49.7
Dolomite 26.0 27.2 27.5
Micas 6.3 5.7 6.6
Clay Minerals 9.0 8.6 10.1
Calcite 3.0 3.7 4.1
Pyrite 2.2 0.2 0.2
Anhydrite/Gypsum 0.4 0.8 0.9
Fe- Oxides 0.2 0.4 0.3
TCM 1.5 0.9 0.2
Other* 0.3 0.5 0.4
Total 100 100 100
*including amphibole, ilmenite and rutile
Table 3c. Modal data used for gold deportment from triple
refractory ore samples
Mineral Mass,
wt%
Sample ID
Rougher
Feed
Rougher
Tails
Cleaner
Tails
Rougher
Conc.
Chalcopyrite 1.8 0.1 0.1 85.4
Other Cu-Sulfides 0.2 0.0 0.0 7.1
Pyrite 4.3 0.6 22.6 6.3
Other Sulphides 0.2 0.0 2.5 0.2
Quartz 38.9 41.8 20.8 0.1
Plagioclase 14.5 16.6 8.8 0.0
K-F eld spar 3.4 3.8 0.9 0.0
Micas 23.7 25.0 25.6 0.3
Chlorite 5.0 5.1 4.6 0.1
Clay Minerals 3.3 2.9 5.3 0.1
Anhydrite/Gypsum 1.9 1.4 5.7 0.0
Fe- Oxides 1.6 1.7 0.4 0.0
Other* 1.0 1.0 3.0 0.0
Total 100 100 100 100
*including amphibole, apatite, carbonates and ilmenite/rutile
inclusions (average grain size 2µm –4µm) mostly within
arsenopyrite and pyrite in the concentrate and within sili-
cates and pyrite in the tailings (Plate 6). No visible gold
grains were noted in the CIL Leach stream samples for the
double refractory ores.
Invisible Gold (Sub-Microscopic Gold) Mineralogy
Concentration of invisible gold in sulfides, Fe-Oxides and
TCM was carried out using a Cameca IMS 3F SIMS instru-
ment. Different morphological types of pyrites (coarse,
fine, porous, aggregates of microcrystalline/ disseminated
pyrite) and TCM (coarse/medium grained TCM and fine
disseminated and composite TCM) were identified by opti-
cal microscopic study and dynamic SIMS analysis was car-
ried out for each of the varieties to quantify the invisible
gold concentration.
Dynamic SIMS analysis data indicated 11% invisible
gold in Cu-Au refractory ore (Table 4a) which was con-
tributed from Fe-Oxides (6%), pyrite (2.5%) and copper
sulfides (2.5%). In double refractory and triple refractory
ore, pyrite was the dominant gold carrier accounting for
94% and 88% of total gold respectively (Table 4b and
4c). In process stream samples from the Cu-Au refractory
ore, chalcopyrite was the main invisible gold carrier and
accounted for 4.5% of total Au in the Final Concentrate.
In the cleaner scavenger tail, Fe-Oxides and pyrite were
the main invisible gold carriers accounting for 12% and
9% of total Au respectively. In the rougher tail, Fe-Oxides
accounted for 22% of total Au (Table 4a). In process stream
samples from the double refractory ore, pyrite was a mod-
erate gold carrier accounting for 23% of total gold in the
POX/CIL residue and 28% in the CIL residue (Table 4b).
In process stream samples from the triple refractory ore,
pyrite was the dominant gold carrier accounting for 85% of
total gold in the pyrite scavenger rougher concentrate and
76% in the TCM rougher concentrate (Table 4c).
Preg-Robbed Surface Gold Mineralogy in TCM
In double refractory gold ore samples, high variability in
gold-robbed surface gold largely due to the amount of
Table 3a. Modal data used for gold deportment from copper-
gold ore samples
Mineral Mass,
wt%
Sample ID
Rougher
Feed
Rougher
Tails
Cleaner
Tails
Rougher
Conc.
Chalcopyrite 1.8 0.1 0.1 85.4
Other Cu-Sulfides 0.2 0.0 0.0 7.1
Pyrite 4.3 0.6 22.6 6.3
Other Sulphides 0.2 0.0 2.5 0.2
Quartz 38.9 41.8 20.8 0.1
Plagioclase 14.5 16.6 8.8 0.0
K-Feldspar 3.4 3.8 0.9 0.0
Micas 23.7 25.0 25.6 0.3
Chlorite 5.0 5.1 4.6 0.1
Clay Minerals 3.3 2.9 5.3 0.1
Anhydrite/Gypsum 1.9 1.4 5.7 0.0
Fe- Oxides 1.6 1.7 0.4 0.0
Other* 1.0 1.0 3.0 0.0
Total 100 100 100 100
*including amphibole, apatite, carbonates and ilmenite/rutile
Table 3b. Modal data used for gold deportment from double
refractory ore
Mineral Mass, wt%
Sample ID
Feed
POX/CIL
Residue
CIL
Residue
Quartz 51.1 52.0 49.7
Dolomite 26.0 27.2 27.5
Micas 6.3 5.7 6.6
Clay Minerals 9.0 8.6 10.1
Calcite 3.0 3.7 4.1
Pyrite 2.2 0.2 0.2
Anhydrite/Gypsum 0.4 0.8 0.9
Fe- Oxides 0.2 0.4 0.3
TCM 1.5 0.9 0.2
Other* 0.3 0.5 0.4
Total 100 100 100
*including amphibole, ilmenite and rutile
Table 3c. Modal data used for gold deportment from triple
refractory ore samples
Mineral Mass,
wt%
Sample ID
Rougher
Feed
Rougher
Tails
Cleaner
Tails
Rougher
Conc.
Chalcopyrite 1.8 0.1 0.1 85.4
Other Cu-Sulfides 0.2 0.0 0.0 7.1
Pyrite 4.3 0.6 22.6 6.3
Other Sulphides 0.2 0.0 2.5 0.2
Quartz 38.9 41.8 20.8 0.1
Plagioclase 14.5 16.6 8.8 0.0
K-F eld spar 3.4 3.8 0.9 0.0
Micas 23.7 25.0 25.6 0.3
Chlorite 5.0 5.1 4.6 0.1
Clay Minerals 3.3 2.9 5.3 0.1
Anhydrite/Gypsum 1.9 1.4 5.7 0.0
Fe- Oxides 1.6 1.7 0.4 0.0
Other* 1.0 1.0 3.0 0.0
Total 100 100 100 100
*including amphibole, apatite, carbonates and ilmenite/rutile