194 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
fuel fired direct heating unit being very compact, the elec-
tric indirect heating was larger and required significantly
different maintenance windows. Due to the mine being
built in Canada, this needed to all fit within a pre-engi-
neered process plant building, which required engineers to
really plan the access corridors and equipment placement
to maximise building floor space utilization.
The regeneration kiln has no burner control unit, but
this space is taken up with the electrical boxes for the elec-
trical components plus the backup battery (located near the
feed end of the kiln). The electrical boxes were advanta-
geous to be as close to the unit as possible, while also taking
up the minimum footprint and allowing access.
Back-up battery was essential for the kiln as the induc-
tion heating does not shut-off immediately (source is still
hot) when a power outage occurs, thus the rotation drive
will remain on to keep the kiln tube from heating /cooling
unevenly and warping.
Startup and shutdown philosophy was a key consid-
eration in the design. An electrically heated circuit has the
additional risk, unlike conventional designs, of unplanned
electrical outages. In order to mitigate the impact of
unplanned electrical outages from a processing, personnel
safety, and equipment protection perspective, and number
of design features were incorporated. Table 1 outlines the
key risks identified, and mitigations incorporated in the
design.
For the SO2 burner unit, going to electric had signifi-
cant challenges as a lot of the circuits are all intertwined with
the burner management unit, which is typically started up
on fossil fuels and then swapped to molten sulphur, which
allows for startup heat, and standby heat to be managed
through the burner control unit.
In the electric SO2 burner unit, we have an electric air
heat-up unit, which pre-heats air until we can start burning
sulphur. This heated air is pushed through the burner unit
so that the ancillary units can start operating, such as the
steam generation for steam-jacketed pipes, the air pre-heat
air recycle and ensuring the post-burner cooling circuit is
controlling properly before sulphur burning to ensure we
limit the amount of sulphurous acid created.
Operational Considerations
The electric elution system is expected to be improved from
an operational perspective compared to a fossil fuel-pow-
ered system, because even the best of those systems have
some leakage in their ducting, causing odour and particu-
late impacts. This all-electric installation, is expected to be
much cleaner to operate.
Operators will need to ensure they are aware of the heat-
up and cool-down periods for induction heating sources, as
this can be significantly longer than fossil fuel. All of the
machinery is well insulated and guarded so this should not
cause any significant operational challenges, however for
tight shut-down windows this should be considered for safe
maintenance planning.
COST IMPACT
The capital cost of this change was in the low 7 figures order
of magnitude CAD additional direct costs, with additional
costs for installation or managing associated technical chal-
lenges. The cost of power in BC is around 6.5 c/kwh, so
the operating cost was lower, and had a payback period of
around 12 months in total based on standard efficiencies
and unit consumption details.
ESTIMATION OF REDUCED CARBON
DIOXIDE EQUIVALENT IMPACT
With an average demand power of the additional electric
heating of 3400 kW, and design operating hours of 8060 a
year, the following table illustrates the difference in scope 1
and 2 emissions for conventional vs electrical heating
design.
With an annual reduction of in the order of 2000
tCO2e/annum, equivalent to carbon equivalent emis-
sions of ~440 conventional vehicles, this is an appreciable
impact on the operating CO2 equivalent emissions of the
Blackwater Mine. For processing facilities connected to
grids with high emissions factors, electrification of fuel-
based heating circuits may not provide a benefit. A compar-
ison in the table for grids with different emissions factors
Table 1. Startup and shutdown risks and mitigations
Material Risk Identified Mitigation
Power Outage causes rotation
drive of kiln to stop while
induction heaters still hot
Backup battery on kiln
rotation drive
Plant experiences unplanned
downtime—SO2 burner
cannot stop quickly or
refractory will crack
Standby electric air heater
will keep refractory at high
temperature to minimize
damage and start up timing
Power outage causes liquid
pumps to stop while
induction coils still at high
temperature
Backup power generation
study completed to ensure
power is back online within
short window and additional
pressure reliefs added
Power outage causes steam
jackets to not function around
molten sulphur piping
Standby heat generation and
startup heat generation (both
electric) on backup power
for when SO
2 burner unit is
down
fuel fired direct heating unit being very compact, the elec-
tric indirect heating was larger and required significantly
different maintenance windows. Due to the mine being
built in Canada, this needed to all fit within a pre-engi-
neered process plant building, which required engineers to
really plan the access corridors and equipment placement
to maximise building floor space utilization.
The regeneration kiln has no burner control unit, but
this space is taken up with the electrical boxes for the elec-
trical components plus the backup battery (located near the
feed end of the kiln). The electrical boxes were advanta-
geous to be as close to the unit as possible, while also taking
up the minimum footprint and allowing access.
Back-up battery was essential for the kiln as the induc-
tion heating does not shut-off immediately (source is still
hot) when a power outage occurs, thus the rotation drive
will remain on to keep the kiln tube from heating /cooling
unevenly and warping.
Startup and shutdown philosophy was a key consid-
eration in the design. An electrically heated circuit has the
additional risk, unlike conventional designs, of unplanned
electrical outages. In order to mitigate the impact of
unplanned electrical outages from a processing, personnel
safety, and equipment protection perspective, and number
of design features were incorporated. Table 1 outlines the
key risks identified, and mitigations incorporated in the
design.
For the SO2 burner unit, going to electric had signifi-
cant challenges as a lot of the circuits are all intertwined with
the burner management unit, which is typically started up
on fossil fuels and then swapped to molten sulphur, which
allows for startup heat, and standby heat to be managed
through the burner control unit.
In the electric SO2 burner unit, we have an electric air
heat-up unit, which pre-heats air until we can start burning
sulphur. This heated air is pushed through the burner unit
so that the ancillary units can start operating, such as the
steam generation for steam-jacketed pipes, the air pre-heat
air recycle and ensuring the post-burner cooling circuit is
controlling properly before sulphur burning to ensure we
limit the amount of sulphurous acid created.
Operational Considerations
The electric elution system is expected to be improved from
an operational perspective compared to a fossil fuel-pow-
ered system, because even the best of those systems have
some leakage in their ducting, causing odour and particu-
late impacts. This all-electric installation, is expected to be
much cleaner to operate.
Operators will need to ensure they are aware of the heat-
up and cool-down periods for induction heating sources, as
this can be significantly longer than fossil fuel. All of the
machinery is well insulated and guarded so this should not
cause any significant operational challenges, however for
tight shut-down windows this should be considered for safe
maintenance planning.
COST IMPACT
The capital cost of this change was in the low 7 figures order
of magnitude CAD additional direct costs, with additional
costs for installation or managing associated technical chal-
lenges. The cost of power in BC is around 6.5 c/kwh, so
the operating cost was lower, and had a payback period of
around 12 months in total based on standard efficiencies
and unit consumption details.
ESTIMATION OF REDUCED CARBON
DIOXIDE EQUIVALENT IMPACT
With an average demand power of the additional electric
heating of 3400 kW, and design operating hours of 8060 a
year, the following table illustrates the difference in scope 1
and 2 emissions for conventional vs electrical heating
design.
With an annual reduction of in the order of 2000
tCO2e/annum, equivalent to carbon equivalent emis-
sions of ~440 conventional vehicles, this is an appreciable
impact on the operating CO2 equivalent emissions of the
Blackwater Mine. For processing facilities connected to
grids with high emissions factors, electrification of fuel-
based heating circuits may not provide a benefit. A compar-
ison in the table for grids with different emissions factors
Table 1. Startup and shutdown risks and mitigations
Material Risk Identified Mitigation
Power Outage causes rotation
drive of kiln to stop while
induction heaters still hot
Backup battery on kiln
rotation drive
Plant experiences unplanned
downtime—SO2 burner
cannot stop quickly or
refractory will crack
Standby electric air heater
will keep refractory at high
temperature to minimize
damage and start up timing
Power outage causes liquid
pumps to stop while
induction coils still at high
temperature
Backup power generation
study completed to ensure
power is back online within
short window and additional
pressure reliefs added
Power outage causes steam
jackets to not function around
molten sulphur piping
Standby heat generation and
startup heat generation (both
electric) on backup power
for when SO
2 burner unit is
down