Page 425 - Advanced Mine Ventilation
P. 425
394 Advanced Mine Ventilation
Figure 23.8 Incombustibles required to prevent propagation of coal dust explosions.
23.3.4.2 Effect of Moisture
Moisture acts as an inert material, but it is neither regulated nor is any credit given to its
concentration in the coal mine dust. However, rock dusting can be dispensed if the coal
is so wet that water comes out when the coal is squeezed in hand [10].
23.3.4.3 Effect of Methane in Air
Cashdollar [8] shows the impact of methane on the MEC of two coals in Fig. 23.9.
Increasing methane concentrations decreases the MEC for both coals. Hence, the inert
concentration is usually increased if there is methane present in mine airways. US laws
require 1% increase in inert dust content for each 0.1% of increase in methane
concentration.
