8
entering the mine ventilation system at the headgate side
of the panel, air exiting the active longwall face to the tail-
gate entry, and air traveling in the adjacent tailgate entries.
Variations in gas concentrations at this location during the
test is a result of resistance in the mine entries and gob areas
as well as the variation in gas concentrations from the BEP
(GVB).
Sample location TG BLD BEP (Figure 12) measured
340 to 370 ppb SF6. This sample location receives the face
ventilation air coursed down the longwall face, any air in
the secondary flow path behind the shields, and air from
the mined panel gob area adjacent to the tailgate entry [7,
13]. These locations are on fan pressure from the bleeder
fan at the back end of the bleeder system. The TG BLD
BEP sample location is critical as it represents any gas in the
ventilation system prior to ‘fresh’ air mixing and dilution.
Figure 13 shows sample location TGCG. The SF6 at
this location ranges from 100 to 160 ppb for Test 1. In Test
1 of the series, the miner was positioned at Shield 115, close
to the tailgate entry. However, for Test 2 in this Series, to
be more consistent with the other test series, the miner was
repositioned to Shield 35 nearer to the headgate entry, and
0 ppb SF6 was measured. This is because the 22 gas inser-
tion points were located inby the tailgate pillar 1 in inside
the gob extending towards the tailgate BEP. Airflow path-
ways directed the gas directly to the tailgate entry toward
the bleeder fan. Therefore, no gas migrated to the sample
point TGCG.
Mine Methane Percentages
Given the SF6 concentration measurements and model
velocities, what does this effectively mean to the mine engi-
neer? In order to obtain meaningful results for the mine
engineer, the SF6 concentrations were converted to an
Table 7. Test Series D average SF6 concentration measurement at each sample location
Series D TG#1 TG#2 TG#3 TG BLD TGCG TG BLD BEP GVB GOB GOB MID FACE BLD #5
Test 1 0 0 2 83 128 0 0 2 0 0
Test 2 0 0 0 1 355 0 0 3 0 0
Series Average 0 0 1 83 65 355 0 0 2 0 0
Sample Location Average SF6 (ppb)
Figure 11. Individual sample SF6 concentration results for
Test 1 at the TG BLD location in Test Series D
Figure 12. Individual sample SF6 concentration results for
Test 2 at the TG BLD BEP location in Test Series D
Figure 13. Individual sample SF6 concentration results for
the TGCG location in Test Series D
entering the mine ventilation system at the headgate side
of the panel, air exiting the active longwall face to the tail-
gate entry, and air traveling in the adjacent tailgate entries.
Variations in gas concentrations at this location during the
test is a result of resistance in the mine entries and gob areas
as well as the variation in gas concentrations from the BEP
(GVB).
Sample location TG BLD BEP (Figure 12) measured
340 to 370 ppb SF6. This sample location receives the face
ventilation air coursed down the longwall face, any air in
the secondary flow path behind the shields, and air from
the mined panel gob area adjacent to the tailgate entry [7,
13]. These locations are on fan pressure from the bleeder
fan at the back end of the bleeder system. The TG BLD
BEP sample location is critical as it represents any gas in the
ventilation system prior to ‘fresh’ air mixing and dilution.
Figure 13 shows sample location TGCG. The SF6 at
this location ranges from 100 to 160 ppb for Test 1. In Test
1 of the series, the miner was positioned at Shield 115, close
to the tailgate entry. However, for Test 2 in this Series, to
be more consistent with the other test series, the miner was
repositioned to Shield 35 nearer to the headgate entry, and
0 ppb SF6 was measured. This is because the 22 gas inser-
tion points were located inby the tailgate pillar 1 in inside
the gob extending towards the tailgate BEP. Airflow path-
ways directed the gas directly to the tailgate entry toward
the bleeder fan. Therefore, no gas migrated to the sample
point TGCG.
Mine Methane Percentages
Given the SF6 concentration measurements and model
velocities, what does this effectively mean to the mine engi-
neer? In order to obtain meaningful results for the mine
engineer, the SF6 concentrations were converted to an
Table 7. Test Series D average SF6 concentration measurement at each sample location
Series D TG#1 TG#2 TG#3 TG BLD TGCG TG BLD BEP GVB GOB GOB MID FACE BLD #5
Test 1 0 0 2 83 128 0 0 2 0 0
Test 2 0 0 0 1 355 0 0 3 0 0
Series Average 0 0 1 83 65 355 0 0 2 0 0
Sample Location Average SF6 (ppb)
Figure 11. Individual sample SF6 concentration results for
Test 1 at the TG BLD location in Test Series D
Figure 12. Individual sample SF6 concentration results for
Test 2 at the TG BLD BEP location in Test Series D
Figure 13. Individual sample SF6 concentration results for
the TGCG location in Test Series D