Page 391 - Advanced Mine Ventilation

360 Advanced Mine Ventilation

Figure 21.7 Typical series of longwall panels.

3. Bleeder ventilation should not be used.
4. The active gob must be progressively sealed.
5. Inerting gases should be injected into the active gob.
6. Gob wells, if needed, must operate naturally or with very low negative pressure (no more
than 10 inches of water gauge).

Fig. 21.7 shows a typical series of longwall panels that are progressively sealed and
isolated from each other. When all the panels are mined out, the district is sealed with
barrier seals and isolated from active mine workings.

21.3.4 Inertization

The surest way to prevent spontaneous combustion of fallen coal in longwall gobs is to
seal the area and maintain a low oxygen content of 4% or lower. The inertization can
be as follows:
• Self-inertization or
• Induced inertization.

21.3.4.1 Self-Inertization

In room and pillar mining, pillar extraction can be so designed that mined out area is
submerged in water. This provides excellent inertization but is possible only in highly
inclined coal seams.
Most commonly, self-inertization is provided by the methane gas released from coal
seams in the gas emission space. Again, this is possible only in rare cases (such as
mines in Buchanan County, Virginia) where the gob produced 15 to 30 million cubic