Page 27 - Advanced Mine Ventilation

10 Advanced Mine Ventilation

An example:

Calculate the density of air, W 2 on top of Mt. Everest at 29,000 ft where

3
W 1 ¼ 0:075 lb ft at the sea level.

4:526
288 0:00198 29; 000 3

W 2 ¼ 0:075 ¼ 0.060 lb=ft
288
1.3.1.6 Pressure Versus Fluid Head
In coal mining practices, ventilation pressures are small in magnitude and hence they
are measured by inches of water or mercury. Water and other liquid pressures are
measured in pounds per square inch.
The equation for conversion is shown in Eq. (1.8).

p ¼ W 1 H 1 ¼ W 2 H 2 (1.8)

2 3
where p is the pressure in lbs/ft ;W 1 ,W 2 are the density of the fluid in lb/ft ;H 1 ,H 2
are height of the fluid column in feet.
An example:
Atmospheric pressure of air is measured in inches of mercury. Typically it is 30 inches Hg.
Convert it into inches of water.
Density of mercury is 13.6; water is 1.00.
Using Eq. (1.8), atmospheric pressure ¼ 30 13.6 ¼ H 2 • 1.
Hence, H 2 ¼ 408 inches or 34 feet of water.
Example 1:
2
A mine fan is running at 10 inches of water. Convert it into lb/ft .
3 10 2
p ¼ W 2 H 2 ¼ 62.4 lb/ft ¼ 52 lb/ft
12
It is important to remember that:
1 inch of water ¼ 5.2 lb/ft 2
1 inch of Hg ¼ 13.6 inches of water
1 psi ¼ 2.036 inches of Hg ¼ 27.7 inches of water.

1.4 Pollutant Control Strategy

In modern, highly mechanized and productive coal mines, it is not possible to dilute
the respirable dust and gases generated by the mining process to safe levels by venti-
lation alone. Engineering control of a pollutant requires the following strategy:

1. Minimize the generation of dust or gas at the source.
2. Suppress the dust/gas at the source.
3. Collect or contain the pollutant at the source.
4. Dilute the remaining pollutant by ventilation to safe levels.