primary escapeway loses significant
pressure early in the mains due to a
segregated belt underpass. This
allows air to travel from the
primary escapeway to the travel
road. This could be easily
corrected with the installation of a
vehicle door. Additionally there is a
200 Pa pressure drop in the belt road
around the 2500 m mark. This is
caused by a high resistance
ventilation control device (VCD)
located in the belt road. This VCD
would have likely been installed to
achieve compliance with belt
segregation. The result is an increase
in the static pressure of the belt road
and the increased level of
contamination of the primary
escapeway in the event of a belt fire.
In fact, the primary escapeway
suffers less contamination if this
VCD is removed from the model.
This is a good example of where
compliance does not necessarily
result in lower risk.
Conclusion
A line of stoppings will not prevent
contaminants from a belt fire entering
a primary escapeway, if the belt road
is at a higher static pressure than the
primary escapeway. For the examples
analysed, segregation of the belt road
from all other roadways usually
resulted in the belt road being at a
higher pressure than surrounding
intake airways.
Consideration needs to be given to
the static pressure differential
between separated escapeways. The
only way to ensure that a contaminant
does not enter the primary escapeway
is to ventilate the mine such that the
primary escapeway is generally at a
higher pressure than the surrounding
roadways. Ideally, the primary
escapeway should have the highest
static pressure of any adjacent
roadways.
Consideration should also be given
to establishing primary escapeways
that are not the main travel road in
the mine. This will allow for the
following:
n
n
Provide a primary escapeway for
the full length of the main headings
free from contaminants in the event
of a fire in the belt road or travel
road.
n
n
Ease of access to the belt road and
less issues with damaged stoppings
or leaking vehicle doors.
n
n
Improve early detection of heatings
and small fires (i.e. via smell).
Consideration should be given to
putting more focus on reducing the
level of risk to personnel than just being
compliant. There are several examples
from the modelling conducted where
compliance is achieved but a more
hazardous mine is the result.
Note
This article is based on a presentation given
at the Coal Operators’ Conference 2014,
12 – 14 February 2014, Wollongong, Australia.
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