3792 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
increased recovery. During the project’s metallurgical test
work, it was demonstrated that ore samples were readily
amenable to both gravity concentration and cyanide leach-
ing. It should be noted that due to the inclusion of grav-
ity concentration, the liberated gold is removed before
leaching which is therefore already improving process sta-
bility. The improved output consistency of HPGR-based
circuits is therefore more influential in flotation circuits.
Additionally, in this circuit the HPGR is separated from
the ball mill and recovery circuit with a fine ore bin which
will help feed stability. However, with the HPGR provid-
ing higher levels of product size consistency there is still the
potential for increased recovery, and this could be a topic
for future examination.
Leaching kinetics and therefore recoveries are influ-
enced by the particle permeability. Literature has demon-
strated that HPGRs do introduce microfractures in the
gangue matrix, particularly in the coarser size fractions
(Baum et al., 1997) with up to 60% higher rock matrix
fracturing compared to traditional crushing (Baum and
Ausburn, 2011).
In addition to particle permeability benefits, Sherman
and Collins challenged that steel grinding media consump-
tion can impact downstream metallurgical factors and
therefor cyanide consumption. The oxidation of the grind-
ing media does influence the gold extraction in cyanide-
based leaching (Rabieh, Eksteen and Albijanic, 2017). A
relationship between ball make-up size and media con-
sumption can be considered based on Bond’s theory which
suggest that whilst improving the ball mill feed, the make-
up ball size can be changed, leading to potential increased
recovery and reduced contamination of gold cyanidation
circuits. A possible reduction of cyanide consumption
through incorporation of HPGR circuit design was not
considered as part of this project but could be evaluated in
future work.
TEST WORK AND SCALE-UP
HPGR base line and scale up testing for the project was
done at COREM in Quebec, Canada using an Enduron ®
pilot HPGR RPP 80/25. This HPGR unit is shown in
Figure 3 with technical specifications shown in Table 2.
Since HPGR began being incorporated into hard rock min-
ing circuits most global installations have been sized using a
pilot HPGR and the method of scale up has been accepted
as industry standard. Additionally, there are many papers
Figure 2. Comparison of Côté and Gosselin abrasion indices
(refer to NI 43-101 TECHNICAL REPORT -FINAL)
Table 2. HPGR specification
Parameter Specification
Capacity Approximately 6 t/h to 8 t/h, depending on
the opening of the rolls, pressure, and ore
density, based on COREM’s current facilities
Roll Diameter 800 mm
Roll Width 250 mm
Motor Force 250 kw each
Studs Diameter: 16 mm
Depth: 5 mm
Control
Parameters
• Ore Types: All
• Feed Type: Choke feed
• %humidity: 14%, depending on ore
type (10% for standard tertiary)
• Operating Pressure (N2): Max 115 bars
• Roll Opening (zero gap): 2, 5, 10, or
15 mm
• Roll Speed: 11–24RPM
Figure 3. Enduron® RPP 80/25 Industrial Pilot HPGR
increased recovery. During the project’s metallurgical test
work, it was demonstrated that ore samples were readily
amenable to both gravity concentration and cyanide leach-
ing. It should be noted that due to the inclusion of grav-
ity concentration, the liberated gold is removed before
leaching which is therefore already improving process sta-
bility. The improved output consistency of HPGR-based
circuits is therefore more influential in flotation circuits.
Additionally, in this circuit the HPGR is separated from
the ball mill and recovery circuit with a fine ore bin which
will help feed stability. However, with the HPGR provid-
ing higher levels of product size consistency there is still the
potential for increased recovery, and this could be a topic
for future examination.
Leaching kinetics and therefore recoveries are influ-
enced by the particle permeability. Literature has demon-
strated that HPGRs do introduce microfractures in the
gangue matrix, particularly in the coarser size fractions
(Baum et al., 1997) with up to 60% higher rock matrix
fracturing compared to traditional crushing (Baum and
Ausburn, 2011).
In addition to particle permeability benefits, Sherman
and Collins challenged that steel grinding media consump-
tion can impact downstream metallurgical factors and
therefor cyanide consumption. The oxidation of the grind-
ing media does influence the gold extraction in cyanide-
based leaching (Rabieh, Eksteen and Albijanic, 2017). A
relationship between ball make-up size and media con-
sumption can be considered based on Bond’s theory which
suggest that whilst improving the ball mill feed, the make-
up ball size can be changed, leading to potential increased
recovery and reduced contamination of gold cyanidation
circuits. A possible reduction of cyanide consumption
through incorporation of HPGR circuit design was not
considered as part of this project but could be evaluated in
future work.
TEST WORK AND SCALE-UP
HPGR base line and scale up testing for the project was
done at COREM in Quebec, Canada using an Enduron ®
pilot HPGR RPP 80/25. This HPGR unit is shown in
Figure 3 with technical specifications shown in Table 2.
Since HPGR began being incorporated into hard rock min-
ing circuits most global installations have been sized using a
pilot HPGR and the method of scale up has been accepted
as industry standard. Additionally, there are many papers
Figure 2. Comparison of Côté and Gosselin abrasion indices
(refer to NI 43-101 TECHNICAL REPORT -FINAL)
Table 2. HPGR specification
Parameter Specification
Capacity Approximately 6 t/h to 8 t/h, depending on
the opening of the rolls, pressure, and ore
density, based on COREM’s current facilities
Roll Diameter 800 mm
Roll Width 250 mm
Motor Force 250 kw each
Studs Diameter: 16 mm
Depth: 5 mm
Control
Parameters
• Ore Types: All
• Feed Type: Choke feed
• %humidity: 14%, depending on ore
type (10% for standard tertiary)
• Operating Pressure (N2): Max 115 bars
• Roll Opening (zero gap): 2, 5, 10, or
15 mm
• Roll Speed: 11–24RPM
Figure 3. Enduron® RPP 80/25 Industrial Pilot HPGR