significant reduction in the number of
main headings, which causes the static
pressure of primary escapeway to peak
in this area. It is possible to see that the
general pressure gradient trend of the
segregated belt road is flatter than that
of the primary escapeway, causing the
belt road to be at a higher static
pressure than the primary escapeway.
This results in the leakage of
contaminant into the primary
escapeway in the event of a belt fire.
This scenario had 17 vehicle doors
positioned along the trunk belt system.
This highlights the need for vehicle
and personnel access to the belt road
and subsequent issues with quality of
stoppings and leakage.
Case 2
Case 2 is based on a longwall mine in
the Bowen Basin in Queensland,
Australia. The trunk conveyor of the
mine is generally segregated on both
sides from the surrounding intakes
with 106 segregation stoppings. The
primary escapeway of the mine is
the main travel road.
This scenario involved the most
elaborate layout for segregation of
the belt road of all the scenarios
analysed. Table 1 shows that the
contaminant result for the longwall
face is 53 ppm regardless of whether
the segregation stoppings are in
place or not. The mains development
panel showed a reduction of 15 ppm
to 1 ppm with the removal of the
segregation stoppings and another
development panel showed a rise
from 1 ppm to 7 ppm. The primary
escapeway, however, showed a
significant increase from 6 ppm to
31 ppm with the removal of the
segregation stoppings. The pressure
gradient plot for Case 2 shown in
Figure 4 shows the extent that this
particular operation has gone to get
the pressure in the belt road to below
the pressure in the primary
escapeway (travel road).
The step in the pressure gradient
for the belt road at the 2000 m mark
is due to the placement of a
regulator and an air dump in the belt
road. This does a good job reducing
the pressure of the belt road and
largely prevents leakage of the
contaminant into the primary
escapeway. The infrequent instances
when the belt road has a higher
static pressure than the adjacent
primary escapeway results in the
low result of 6 ppm. The air dump
directs air out of the belt road into
adjacent intake roadways. It is this
air that is directed to the longwall
– and this is the reason for the
53 ppm result for the longwall face.
Case 3
Case 3 is based on a longwall mine
in the Bowen Basin in Queensland,
Australia. The trunk conveyor of the
mine is generally segregated on both
sides from the surrounding intakes
with 64 segregation stoppings. The
primary escapeway of the mine is a
roadway separate from the main
travel road and on the other side of
the trunk conveyor.
This scenario initially showed the
most promise for having a simple
design and maintaining a primary
escapeway at a pressure above the
adjacent belt road. However, the
pressure gradient plot in Figure 5
shows that this is not the case. The
belt road is generally at a greater
static pressure than the adjacent
primary escapeway. This is reflected
in the results in Table 1, with
arguably better results achieved with
the segregation stoppings
removed from the model. The
primary escapeway showed an
increase in contaminant
concentration from 26 ppm to
29 ppm with the segregation
stoppings removed.
There are two ways this scenario
could be dramatically improved. The
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World Coal
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September 2014
Figure 4.
Case 2: pressure plot.
Figure 5.
Case 3: pressure plot.
