XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 193
propane-powered or heated components within the process
plant facility to reduce the carbon footprint of the Project.
This paper outlines the circuits commonly utilising natu-
ral gas or diesel which have been designed with electric
heating. Technical challenges to ensure the design operates
safely in the case of electrical outages, along with solutions
selected are discussed.
ENGINEERING DESIGN
The design included electric elution heating, electric kiln
and electric smelting, in lieu of the typical use of Natural
Gas or Diesel as a heat source. The SO2 system also used
electric heat and recycled steam rather than fossil fuels for
both sulphur melting and pre-heat stages, as well as tempo-
rary no-load heat scenarios. This allowed for the entire pro-
cess facility to have no fossil fuel power used in the entire
process. Figure 1 shows a simple block diagram identify-
ing the units typically utilizing fossil fuels that were transi-
tioned to fully electric for this processing facility.
Power Requirements
There were four units that were changed from conventional
fossil fuel to electric power, namely the smelting furnace,
carbon reactivation kiln, elution heater and the sulphur
burner start up and standby heater units. In total, over
6000kW of installed power was put in to replace typical
fossil fuel units.
The heat up for the elution takes 4200kW to meet the
cycle time required for processing at high throughput and
gold grade, and once it reaches steady state, this circuit uses
a lot less power. The heat up period is approximately 2 × 2
hrs per day, and then approximately 1/3rd of peak power
is used to keep the circuit going for the next 7 hrs, fol-
lowed by and then 3 hrs of cooldown/carbon transfer. The
kiln operates 24/7 at around 600kW of consistent demand
load. The smelting furnace operates for approximately 4 hrs
per day at 250kW demand. The average demand power of
the additional electric heating is approximately 3400 kW.
Technical Challenges
A number of technical challenges were considered during
the design to ensure safe and effective responses to electrical
outages. These included, Electrical design, equipment size
and layout, and start-up /shut-down philosophy.
A key consideration for the electrical design is that
low voltage power was typically required due to the heat-
ing requirement. These low voltage but high amp cables
were quite large, and numerous particularly for the elution
heater which required 4.2MW of electrical power at 600V.
This required 18 individual large cables, which all had to fit
into the same electrical termination boxes.
On top of the electrical termination challenges, much
of this cable had to be run in conduits to maintain path-
ways for maintenance of equipment, vehicles and person-
nel. Due to the cable type and size, each conduit could only
fit 3 cables per conduit, which meant there was significant
planning prior to the first concrete pours to ensure that this
type of equipment could be installed and maintained.
Beyond the electrical requirements, the equipment
itself required some other challenges, with a standard fossil
Figure 1. Circuits involving electric heating (elution heating, electric kiln and electric smelting, sulphur melting and pre-heat
stages)
propane-powered or heated components within the process
plant facility to reduce the carbon footprint of the Project.
This paper outlines the circuits commonly utilising natu-
ral gas or diesel which have been designed with electric
heating. Technical challenges to ensure the design operates
safely in the case of electrical outages, along with solutions
selected are discussed.
ENGINEERING DESIGN
The design included electric elution heating, electric kiln
and electric smelting, in lieu of the typical use of Natural
Gas or Diesel as a heat source. The SO2 system also used
electric heat and recycled steam rather than fossil fuels for
both sulphur melting and pre-heat stages, as well as tempo-
rary no-load heat scenarios. This allowed for the entire pro-
cess facility to have no fossil fuel power used in the entire
process. Figure 1 shows a simple block diagram identify-
ing the units typically utilizing fossil fuels that were transi-
tioned to fully electric for this processing facility.
Power Requirements
There were four units that were changed from conventional
fossil fuel to electric power, namely the smelting furnace,
carbon reactivation kiln, elution heater and the sulphur
burner start up and standby heater units. In total, over
6000kW of installed power was put in to replace typical
fossil fuel units.
The heat up for the elution takes 4200kW to meet the
cycle time required for processing at high throughput and
gold grade, and once it reaches steady state, this circuit uses
a lot less power. The heat up period is approximately 2 × 2
hrs per day, and then approximately 1/3rd of peak power
is used to keep the circuit going for the next 7 hrs, fol-
lowed by and then 3 hrs of cooldown/carbon transfer. The
kiln operates 24/7 at around 600kW of consistent demand
load. The smelting furnace operates for approximately 4 hrs
per day at 250kW demand. The average demand power of
the additional electric heating is approximately 3400 kW.
Technical Challenges
A number of technical challenges were considered during
the design to ensure safe and effective responses to electrical
outages. These included, Electrical design, equipment size
and layout, and start-up /shut-down philosophy.
A key consideration for the electrical design is that
low voltage power was typically required due to the heat-
ing requirement. These low voltage but high amp cables
were quite large, and numerous particularly for the elution
heater which required 4.2MW of electrical power at 600V.
This required 18 individual large cables, which all had to fit
into the same electrical termination boxes.
On top of the electrical termination challenges, much
of this cable had to be run in conduits to maintain path-
ways for maintenance of equipment, vehicles and person-
nel. Due to the cable type and size, each conduit could only
fit 3 cables per conduit, which meant there was significant
planning prior to the first concrete pours to ensure that this
type of equipment could be installed and maintained.
Beyond the electrical requirements, the equipment
itself required some other challenges, with a standard fossil
Figure 1. Circuits involving electric heating (elution heating, electric kiln and electric smelting, sulphur melting and pre-heat
stages)