MINE VENTILATION
Controlling the flow
Howden was previously awarded a contract for
the installation of the main ventilation fans at
Codelco’s Chuquicamata underground project
in Chile, one of the world’s largest
underground mines (Credit: Howden)
There is more to underground mine ventilation than volume,
Dan Gleeson reveals
The topic of mine ventilation is set to
become a lot more complex with the
incorporation of new technology,
equipment and regulations.
Operations will have mixed fleets of diesel and
electric equipment alongside a blend of manual,
teleremote, semi-autonomous and autonomous
equipment.
These operations will be mining at different
depths depending on the orebody in question
and be governed by various regulations that
dictate the amount of fresh air needed to be
blown in.
This is before factoring in the different mining
methods, sizes of operation, financial capabilities
and average number of blasts per week.
Against this evolving backdrop, an optimal,
efficient, and cost-effective ventilation system
will have to be much more sophisticated than
those that preceded them.
Take back control
“Shortly, I think mine ventilation control will be
even more important,” Jan Nyqvist, ABB Product
Manager, Automation Underground Mining, told
IM. “If you look into ventilation systems of today,
we are using them for several things.”
Pushing air into working areas to improve the
operating environment is the most important use,
Nyqvist suggests. This includes ventilating for
good air quality, the right working temperature,
dust reduction, etc.
This application is closely followed by
ventilating blasting gases, a process that allows
workers to return to the face quickly and safely
after a blast. Here, a combination of ventilation
fans and environmental monitoring stations
distribute air and analyse the environment to
ensure workers come back to production areas
only when it is safe to do so.
“Then, the third one is to ventilate the air from
diesel particulate matter,” Nyqvist said.
It is this latter application coming into focus
today as miners plan for, trial or buy new batteryelectric
or tethered-electric equipment to reduce
their emissions and, in many cases, cut
ventilation costs at their operations.
“That ventilation demand from diesel
particulates will be removed a little bit with the
use of electric vehicles,” Nyqvist explained.
In Canada, for example, operating companies
have to ensure that for every one brake
horsepower of diesel emitted, 100 cubic feet per
minute of air (1 kw/0.06 m 3 /s) is pushed into the
operating area.
“From a battery-electric vehicle perspective, if
the whole mine is electric, you are taking out the
100 cfm/bhp rule of thumb,” Randy Ouimet,
Sales Executive at SHYFTinc, part of the Inovinta
Group, told IM.
Without the need to ventilate diesel tail pipe
emissions from mining equipment, the amount of
air needed to be blown in at mine sites in Canada
will fall, meaning the fans installed underground
could get smaller in size.
Former Senior Project Engineer at Goldcorp
(now Newmont), Maarten van Koppen, illustrated
this in a 2018 blog post reviewing the
construction and initial operation of the Ontariobased
Borden mine – billed as the world’s first
all-electric mine.
He said the absence of diesel equipment at the
mine had not only significantly reduced
ventilation requirements and costs, it had also
impacted the design of the mine itself.
“Drifts are now designed to be smaller since
the ventilation ducting is smaller, and the number
of auxiliary fans was cut by half or more,” he
said. “In addition, we avoided the need to
develop a return air raise in the mine, which
probably would have been very visible from the
lake in winter due to the condensation plume.”
A transition away from diesel-powered
vehicles to electric-powered vehicles is likely to
reduce ventilation requirements all over the
world, as Hugo Dello Sbarba, Howden’s Ventsim™
– Director, explained.
“Conventional systems with diesel require you
to push a lot of air into the stope/area during
operations,” he said. “With electrification, you
will be able to reduce that volume of air to a
much lower level.”
Javier Fernández, Managing Director of Zitron
Australia, added to this.
“The minimum amount of fresh air required for
mines with 100% electric vehicle/equipment
fleets, will not be calculated by reference to a
certain ratio of air flow per kW of diesel engine,
as is done today with the use of diesel-powered
machinery,” he said.
Yet, as everyone in the industry is pointing out,
that does not mean mines will require no
ventilation. Far from it.
“Mines will still have to clear blast fumes,”
Dello Sbarba told IM.
Just as diesel particulate matter is dangerous
for those working underground, so too are the
fumes that come from blasting operations. This is
why mines have numerous environmental
monitoring stations in place to ensure miners
return to the face when these fumes have
dissipated.
The speed of return is dictated by the blasting
practice itself, the accuracy of the environmental
monitoring station and just how quickly and
effectively the mine can clear the fumes with the
ventilation system in place.
The ventilation applications of electric mines
will not end with blast fumes.
David Ballantyne, Vice President of Product
Development and Co-founder for Maestro Digital
Mine, explained: “The focus in electric mines will
shift from monitoring diesel emissions to monitor
strata gas emissions, dust and heat.”
Michael Gribbons, VP and Co-founder for
Maestro, added to this: “Mines are getting
deeper and are having to deal with higher strata
temperatures and relative humidity.
“Worker heat stress is becoming a constraint
to production and large, expensive chilling plants
are required to bring the working zones into
compliance.”
Fernández thinks this focus on worker heat
stress and the deepening of mines across the
industry could in fact lead to larger volumes of
fresh, ventilated air being required in all-electric
mines
“When operating at deeper levels, the worker
heat stress will be one of the key parameters for
determining the amount of time that a miner can
stay at the workplace, and ever larger volumes of
fresh air and mine refrigeration systems will be
required.”
He added: “The increased use of new electric
equipment provides us with a good opportunity
for maximisation of productivity and, at the same
time, lowering of energy costs.
“Electric motors are significantly more efficient
JULY/AUGUST 2020 | International Mining 85