Feature
MINE VENTILATION
– A MATTER OF LIFE AND DEATH
By Russell Hattingh, regional manager, AHI-Carrier
A well-functioning heating, ventilation and air conditioning (HVAC) system in a mine
is non-negotiable when it comes to creating a safe working environment for mine
workers.
A
s with any HVAC system, it is imperative to do your
homework when you design an HVAC system for a mine.
WHY DOES A MINE NEED COOLING
IN THE FIRST PLACE?
A mine gets hot as the temperature of the rock increases as you
go deeper. Considering that the crust is floating on the mantle – a
molten layer of magma – and the thickness of the crust is about
60km, it stands to reason that rock temperature will increase
with depth. This increase in temperature means that the rock
adds heat to the shafts and tunnels in a mine. A well-established
deep level mine can have virgin rock temperatures of between
50 0 C and 60 0 C.
Clearly, people and equipment cannot work in conditions
like this, so the air in the tunnels and shafts needs to be cooled.
Heating is rarely, if ever, used in deep level mines. There are
several factors to consider when it comes to maintaining
air quality in a mining context. These include factors like
temperature, humidity, dust, fumes and other harmful gases
(like methane).
When considering air conditioning in a mine, let’s only talk
about temperature and humidity to keep the discussion focused
on cooling. Although there are many parallels, air conditioning
in a mining context is not the same as air conditioning a building.
For starters, the delivery method is vastly different given the
sheer magnitude of cooling required. Open sprays would be
employed instead of cooling coils. A building HVAC designer
would consider the comfort of the occupants. A mine-ventilation
specialist would consider the maximum allowable temperature
(Wet bulb and Dry bulb) to enable people to work. The reason for
this caveat is that providing cooling for a mine is an expensive
business due to the rather large energy requirements of these
systems. When designing for a mine, ventilation specialists will
often try to maximise uncooled air from surface. When this is
Proper and
thorough
research is
imperative when
designing HVAC
for a mine.
42
RACA Journal I January 2020
www.hvacronline.co.za