Page 441 - Advanced Mine Ventilation

410 Advanced Mine Ventilation

Regular mine people follow the rescue teams and do all that is necessary to resume
normal mining.

24.4.2 Air Locking
This technique is used when one is not absolutely sure that the fire is actually dead. It
was permitted in the past but may not be approved today by government agencies, such
as Mine Safety and Health Administration of the United States.
The logic here is to recover the mine or a mine entry in steps. An air lock is built
against the sealed area and the outbye area is fully recovered. The fresh air base is
moved inbye and another air lock is built to recover the next section of the mine/
airway. In repeated steps, thus, the whole area that was on fire is inspected and recov-
ered. Step by step procedures are listed by Mitchell [1]. Reference can be made for
details.

Problem

The following air analysis is received from a sealed area in a mine that was on fire.
Calculate CO Index, Litton Ratio, and Hydrocarbon Ratio to conclude if the fire is
dead.

Gas Concentration
O 2 6% (60,000 ppm)
CH 4 6.5% (65,000 ppm)
CO 700 ppm
C 2 H 6 500 ppm
C 3 H 8 100 ppm
CO 2 8.5%
N 2 ¼ (100 e all above gases)

References

[1] Mitchell DW. Mine fires: prevention, detection, fighting. Maclean Hunter Publishing
Company; 1990. p. 167.
[2] Code of federal regulations, title 30, mineral resources 75.335 and 75.336. 2007. p. 752
[published annually].
[3] Kissell FN, Thimons ED. New stopping designs e an update. Mining Congress Journal July
1981.
[4] Mitchell DW. Personal communications.