992 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
INTRODUCTION
The precious metal deposit, Pueblo Viejo, is located in
the Dominican Republic on the Caribbean Island of
Hispaniola. The Pueblo Viejo gold mining operation
achieved commercial production in January 2013 and is in
the process of expanding its production capacity from 9.5
Mtpa to 14 Mtpa
The Pueblo Viejo mineral processing plant is com-
prised of the following circuits: crushing, grinding,
thickening, and pressure oxidation (POX), followed by
counter-current-decantation (CCD), lime boil, Carbon-
in-Leach (CIL), and cyanide destruction (Figure 1). Four
autoclaves and an oxygen plant form part of the pressure
oxidation circuit. The design basis for the oxygen plant is
to provide the oxygen required to oxidize approximately 80
tph of sulfide sulfur. This is equivalent to 1,200 tph of feed
containing 6.79% sulfide sulfur, assuming a design factor
of 2.2 tons of oxygen per ton of sulfide sulfur. In pressure
oxidation, the ore is oxidized for 60 minutes at a tempera-
ture of 225°C and a pressure of 3,100 kPag (500 PSIG).
Autoclaves are complicated by design and need to be
controlled within design parameters to ensure a safe and
effective operation. The risk of downtime or insufficient
oxidation is extremely high if the autoclave is not managed
according to a predefined strategy. Consequently, Pueblo
Viejo realized the opportunity to improve its autoclave per-
formance by integrating a tailored control system that acts
consistently.
As part of their ongoing improvement efforts, Pueblo
Viejo contracted Woodgrove Technologies to integrate the
AwaRE ® Advanced Process Control (APC) system to man-
age their four autoclaves, which are the core of the com-
plex POX circuit. An APC system serves as a platform to
automate the best operating practices, leveraging knowl-
edge accumulated through years of operation. It aims to
formalize and implement a comprehensive control strategy
based on proven practices, ensuring consistent adherence
to a pre-defined and agreed-upon approach. The effect of
an APC system can be seen in the round-the-clock stability
it creates as it is not subject to human error or an indi-
vidual’s opinion. Since the AwaRE ® APC system is ideal
for applications in autoclaves, its control strategy has been
specifically developed and tailored for effective autoclave
control of this magnitude. It simultaneously controls criti-
cal parameters such as autoclave feed flow, oxygen distribu-
tion in each compartment, overall oxygen addition, and the
High-Pressure Cooling Water (HPCW) addition for each
compartment.
This comprehensive control was able to significantly
optimize the POX process, aligning with the plant’s
Figure 1. Simplified Pueblo Viejo flow diagram with expansion upgrades
INTRODUCTION
The precious metal deposit, Pueblo Viejo, is located in
the Dominican Republic on the Caribbean Island of
Hispaniola. The Pueblo Viejo gold mining operation
achieved commercial production in January 2013 and is in
the process of expanding its production capacity from 9.5
Mtpa to 14 Mtpa
The Pueblo Viejo mineral processing plant is com-
prised of the following circuits: crushing, grinding,
thickening, and pressure oxidation (POX), followed by
counter-current-decantation (CCD), lime boil, Carbon-
in-Leach (CIL), and cyanide destruction (Figure 1). Four
autoclaves and an oxygen plant form part of the pressure
oxidation circuit. The design basis for the oxygen plant is
to provide the oxygen required to oxidize approximately 80
tph of sulfide sulfur. This is equivalent to 1,200 tph of feed
containing 6.79% sulfide sulfur, assuming a design factor
of 2.2 tons of oxygen per ton of sulfide sulfur. In pressure
oxidation, the ore is oxidized for 60 minutes at a tempera-
ture of 225°C and a pressure of 3,100 kPag (500 PSIG).
Autoclaves are complicated by design and need to be
controlled within design parameters to ensure a safe and
effective operation. The risk of downtime or insufficient
oxidation is extremely high if the autoclave is not managed
according to a predefined strategy. Consequently, Pueblo
Viejo realized the opportunity to improve its autoclave per-
formance by integrating a tailored control system that acts
consistently.
As part of their ongoing improvement efforts, Pueblo
Viejo contracted Woodgrove Technologies to integrate the
AwaRE ® Advanced Process Control (APC) system to man-
age their four autoclaves, which are the core of the com-
plex POX circuit. An APC system serves as a platform to
automate the best operating practices, leveraging knowl-
edge accumulated through years of operation. It aims to
formalize and implement a comprehensive control strategy
based on proven practices, ensuring consistent adherence
to a pre-defined and agreed-upon approach. The effect of
an APC system can be seen in the round-the-clock stability
it creates as it is not subject to human error or an indi-
vidual’s opinion. Since the AwaRE ® APC system is ideal
for applications in autoclaves, its control strategy has been
specifically developed and tailored for effective autoclave
control of this magnitude. It simultaneously controls criti-
cal parameters such as autoclave feed flow, oxygen distribu-
tion in each compartment, overall oxygen addition, and the
High-Pressure Cooling Water (HPCW) addition for each
compartment.
This comprehensive control was able to significantly
optimize the POX process, aligning with the plant’s
Figure 1. Simplified Pueblo Viejo flow diagram with expansion upgrades