migrating to other parts of the mine.
The results show that, in some cases,
the benefits of segregation to a person
evacuating a mine in the event of a fire
range from beneficial to detrimental.
This is influenced by many factors,
including the location of that
individual in that particular mine.
Mine scenarios
For the purpose of analysis of belt
segregation, four different mine
layouts were used to model the
effectiveness of the segregation. The
first scenario (Case 0) is a conceptual
model and does not represent the
workings of an actual mine. This was
used so that any ventilation layouts
and analysis results could be
published without concern for
confidentiality. The other three
scenarios (Cases 1 – 3) are based on the
ventilation models from actual
longwall coal mines in Queensland,
Australia. For the purposes of
confidentiality, only the analysis
results are published.
Methodology
Pressures
Pressure gradient plots were generated
for each scenario. These display the
relative static pressure in the mine
roadway from the surface intake to the
longwall and along the return back to
the main fans. The belt road pressure
gradient was also plotted, as were the
pressure gradients of any additional
separated intake roadways.
Contaminant test
A 100 ppm contamination was placed
into the model inside the belt portal
and then modelled to see where the
contaminant would migrate
throughout the mine. This test was
applied to each of the scenarios and
the results recorded. The models were
then modified with all the segregation
stoppings in the mine removed and
the same 100 ppm contamination test
reapplied. This allowed the two
results for the same mine to be
compared. This was used so the
effectiveness of the segregation
stoppings of the scenario could be
measured.
It is important to note that the
numerical value of the contamination
concentration in the results table is
only relevant in respect to the
100 ppm contaminant that was used
for the test. It is primarily for
comparison between models and
between segregation and no
segregation. For example, a 20 ppm
contamination in a primary
escapeway may appear to be
acceptable until one considers that, if
the contamination at the belt portal
was 1000 ppm, then the concentration
in the escapeway would be 200 ppm.
Table 1 displays the model results for
each scenario with the segregation
stoppings in place and also with the
segregation stoppings removed.
The purpose of this test is to
measure the effectiveness of
segregation stoppings in reducing the
spread of contaminants to other parts
of the mine. No consideration has
been given to the dynamic nature of a
fire, the buoyancy and pressure
differentials that are possible from an
active fire.
Case 0
The ventilation layout for Case 0 is
shown in Figure 1. This fictitious
Table 1. Contamination test: modelled segregation stopping effectiveness
Modelled number of
segregation stoppings
Modelled contaminant concentration (ppm)
Belt Portal
LW face
Mains
Dev1
Dev2
Primary escapeway
(maximum)
Case 0 157
100
14
76
16
14
18 or 4*
0
100
31
28
30
27
33 or 27*
Case 1
203
100
7
30
25
0
31
0
100
17
22
21
1
22
Case 2 106
100
53
15
1
1
6
0
100
53
1
7
0
31
Case 3 64
100
21
77
29
44
26
0
100
22
26
24
25
29
* Depending on which heading is classified as the primary escapeway.
48
|
World Coal
|
September 2014
Figure 1.
Case 0: ventilation layout.
