1482 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
obtain a 2 gram sub-split of the material. Each sample was
then mixed with carbon, mounted in epoxy resin, polished,
and carbon-coated for analysis.
Pyrite was the dominant sulfide in the head samples,
with concentrations ranging from 3–13%, with trace to
minor amounts (≤ 2%) of sphalerite and galena detected.
Sulfide quantities are greater in samples 1 through 4, how-
ever, the analysis indicates similar sulfur deportment results
throughout the suite, with pyrite accounting for an average
of 87% of the sulfur in the samples.
The eight head samples sized at –2 mm were subse-
quently analyzed by TIMA and laser ablation inductively
coupled plasma mass spectrometry (LA-ICP-MS) for gold
deportment. TIMA results represent visible gold occur-
rences (≥0.3 µm) followed by LA-ICP-MS for solid solution
gold 0.3 µm). TIMA’s Bright Phase Search (BPS) method
was used for gold characterization. The BPS method will
scan particles with grains that lie in a selected grey level
range. The grey levels selected for the scans were near-white
to white, to detect high atomic number minerals, such as
gold. LA-ICP-MS analyses were made using an Applied
Spectra RESOlution-SE 193 nm excimer laser ablation
instrument coupled with an Agilent 8900 ICP-MS. Samples
were ablated in a helium atmosphere using 12–30 µm laser
spots or 12 µm line scans. Table 3 shows the distribution of
gold in pyrite as visible or solid solution gold, along with
carbon and gold robbing characteristics. Carbon content
and gold robbing capacity are based on chemical analyses
completed on the samples. LA-ICP-MS analyzed sulfides
in the sample for submicron gold. Sulfides analyzed include
pyrite, galena, sphalerite, and arsenopyrite. Distinct mor-
phologies were analyzed for the dominant sulfide (pyrite)
which included coarse, porous, microcrystalline, and dis-
seminated. No discernible trends were evident in the gold
content among the different pyrite morphologies. The gold
content within all the sulfides analyzed in the sample was
summed up and used to determine solid solution gold.
The samples were subsequently characterized by man-
ual scanning electron microscopy (SEM) and Raman spec-
troscopy to characterize the physical properties of the CM
in the polymetallic ore deposit. The head samples were
received at –2 mm and stage crushed to –600 µm to maxi-
mize carbon liberation from gangue minerals while preserv-
ing the carbon grain size. Due to the fine-grained nature
of the CM, samples were screened to –150 µm and run
through a rotary micro-riffler to obtain a 20 g split.
The concentration of CM in the eight samples varies
from very low (0.01%) to higher (0.53%). Sample splits
were run through a heavy liquid density separation to
increase the concentration of CM by removing the sulfides
Table 2. Modal Mineralogy of the eight selected head samples
Mineral Mass, %1 2 3 4 5 6 7 8
Gold Phases 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001
Silver Phases 0.01 0.001 0.001 0.001 0.001 0.01 0.001 0.001
Galena 1.08 0.12 0.04 0.03 0.83 1.14 0.49 0.60
Sphalerite 2.08 1.10 0.14 1.84 0.57 1.66 0.59 1.12
Pyrite 6.37 11.84 13.42 10.05 4.21 5.96 6.20 3.43
Arsenopyrite 0.001 0.04 0.07 0.05 0.34
Copper Sulfosalts 0.04 0.2 0.14 0.41 0.01 0.06 0.01 0.001
Other Sulfide and Sulfosalts 0.03 0.01 0.01 0.00 0.05 0.03 0.02 0.01
Non-Sulfide Gangue 90.40 86.74 86.26 87.67 94.29 91.08 92.65 94.49
Total 99.99 100.00 100.00 100.00 99.99 100.00 99.99 100.00
Table 3. Gold distribution, relative carbon content and gold robbing classification of the eight selected head samples
Sample ID Visible Gold, %Solid Solution Gold, %Carbon Content
Gold Robbing
Classification
1 79.5 20.5 Low Non
2 87.8 12.2 Low Non
3 63.6 36.4 Low Non
4 95.1 4.9 Low Non
5 37.5 62.5 High Highly
6 64.1 35.9 High Highly
7 16.2 83.8 High Highly
8 33.3 66.7 High Highly
obtain a 2 gram sub-split of the material. Each sample was
then mixed with carbon, mounted in epoxy resin, polished,
and carbon-coated for analysis.
Pyrite was the dominant sulfide in the head samples,
with concentrations ranging from 3–13%, with trace to
minor amounts (≤ 2%) of sphalerite and galena detected.
Sulfide quantities are greater in samples 1 through 4, how-
ever, the analysis indicates similar sulfur deportment results
throughout the suite, with pyrite accounting for an average
of 87% of the sulfur in the samples.
The eight head samples sized at –2 mm were subse-
quently analyzed by TIMA and laser ablation inductively
coupled plasma mass spectrometry (LA-ICP-MS) for gold
deportment. TIMA results represent visible gold occur-
rences (≥0.3 µm) followed by LA-ICP-MS for solid solution
gold 0.3 µm). TIMA’s Bright Phase Search (BPS) method
was used for gold characterization. The BPS method will
scan particles with grains that lie in a selected grey level
range. The grey levels selected for the scans were near-white
to white, to detect high atomic number minerals, such as
gold. LA-ICP-MS analyses were made using an Applied
Spectra RESOlution-SE 193 nm excimer laser ablation
instrument coupled with an Agilent 8900 ICP-MS. Samples
were ablated in a helium atmosphere using 12–30 µm laser
spots or 12 µm line scans. Table 3 shows the distribution of
gold in pyrite as visible or solid solution gold, along with
carbon and gold robbing characteristics. Carbon content
and gold robbing capacity are based on chemical analyses
completed on the samples. LA-ICP-MS analyzed sulfides
in the sample for submicron gold. Sulfides analyzed include
pyrite, galena, sphalerite, and arsenopyrite. Distinct mor-
phologies were analyzed for the dominant sulfide (pyrite)
which included coarse, porous, microcrystalline, and dis-
seminated. No discernible trends were evident in the gold
content among the different pyrite morphologies. The gold
content within all the sulfides analyzed in the sample was
summed up and used to determine solid solution gold.
The samples were subsequently characterized by man-
ual scanning electron microscopy (SEM) and Raman spec-
troscopy to characterize the physical properties of the CM
in the polymetallic ore deposit. The head samples were
received at –2 mm and stage crushed to –600 µm to maxi-
mize carbon liberation from gangue minerals while preserv-
ing the carbon grain size. Due to the fine-grained nature
of the CM, samples were screened to –150 µm and run
through a rotary micro-riffler to obtain a 20 g split.
The concentration of CM in the eight samples varies
from very low (0.01%) to higher (0.53%). Sample splits
were run through a heavy liquid density separation to
increase the concentration of CM by removing the sulfides
Table 2. Modal Mineralogy of the eight selected head samples
Mineral Mass, %1 2 3 4 5 6 7 8
Gold Phases 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001
Silver Phases 0.01 0.001 0.001 0.001 0.001 0.01 0.001 0.001
Galena 1.08 0.12 0.04 0.03 0.83 1.14 0.49 0.60
Sphalerite 2.08 1.10 0.14 1.84 0.57 1.66 0.59 1.12
Pyrite 6.37 11.84 13.42 10.05 4.21 5.96 6.20 3.43
Arsenopyrite 0.001 0.04 0.07 0.05 0.34
Copper Sulfosalts 0.04 0.2 0.14 0.41 0.01 0.06 0.01 0.001
Other Sulfide and Sulfosalts 0.03 0.01 0.01 0.00 0.05 0.03 0.02 0.01
Non-Sulfide Gangue 90.40 86.74 86.26 87.67 94.29 91.08 92.65 94.49
Total 99.99 100.00 100.00 100.00 99.99 100.00 99.99 100.00
Table 3. Gold distribution, relative carbon content and gold robbing classification of the eight selected head samples
Sample ID Visible Gold, %Solid Solution Gold, %Carbon Content
Gold Robbing
Classification
1 79.5 20.5 Low Non
2 87.8 12.2 Low Non
3 63.6 36.4 Low Non
4 95.1 4.9 Low Non
5 37.5 62.5 High Highly
6 64.1 35.9 High Highly
7 16.2 83.8 High Highly
8 33.3 66.7 High Highly