Page 431 - Advanced Mine Ventilation

400 Advanced Mine Ventilation

surrounded and manpower and materials gathered to prevent its propagation. Mine
sealing is misconstrued to mean an “end of mining.” On the contrary, it can be,
sometimes, the quickest way to extinguish the fire and recover the mine, especially
if the mine is gassy. The subject of mine sealing and recovery will be discussed under
the following three headings:

• Mine sealing
• Sampling the sealed mine atmosphere and interpretations of data
• Mine recovery

24.1 Mine Sealing

The work of mine sealing can be broadly divided into two teams: (1) surface sealing
team and (2) in-mine sealing team. Such teams are generally a part of normal mine
planning.

24.1.1 Surface Sealing
All openings that can feed air to the underground mine must be closed. These include:

1. Shafts, drifts, and slopes.
2. All boreholes for rock dust, power cable, water, degasification, and diesel fuels. Some of
these boreholes and shafts can be used to monitor the mine atmosphere.
3. Locations for new boreholes to surround the fire area should be selected and materials to
extinguish fire should be gathered. This may be just plain water, nitrogen foam, silica gel so-
lutions, or nitrogen generating equipment, such as a PSA (pressure swing adsorption) unit
that can extract nitrogen from atmosphere. Most seals on these mine openings are made of
steel plates that are covered with rigid urethane foam to make an airtight seal.

24.1.2 In-Mine Seals

All seals/stoppings (a term more popular in mining parlance) used in underground
mines can be divided into three categories:

1. Temporary/ventilation stoppings,
2. Permanent stoppings, and
3. Explosion-proof stoppings.

24.1.2.1 Temporary Stoppings
Such stoppings are routinely made to separate intake airways from return airways.
These need to be sealed and made airtight. Most commonly, they are made of concrete
blocks, but brattice cloth and metal stoppings are also used. The latter can be recovered
and reused. All such stoppings are made airtight by urethane foam sprays.