Page 52 - Advanced Mine Ventilation

Turbulent Dispersion of 3

Pollutants in Mine Airways

Chapter Outline

3.1 Mine Ventilation Systems 35
3.2 Generalized Mass Transfer Model 36
3.3 Instantaneous Stationary Point Source 37
3.4 Continuous Stationary Point Source 38
3.5 Dispersion of Respirable Dust From a Heading 39
3.6 Dispersion in a Leaky Roadway 40
3.7 Concentration Growth in a Roadway With Uniformly Distributed Source 41
Problems 41
References 42

3.1 Mine Ventilation Systems

Mine ventilation systems consist essentially of three components, namely, the mine
geometry, fluids circulating through the mine (mainly air contaminated with pollutant
masses), and mine fans. Because of the velocity of the air and the size of airways, the
flow is generally turbulent. Efficient design of mine ventilation systems depends heavi-
ly on a thorough knowledge of how pollutant masses originate, disperse, and flow in
the mine airways. Mathematical analysis of such turbulent mass transfer processes is,
therefore, an important area of study.
Depending on the geometry of the mine sections, these transfer processes can be
classified into three parts, namely:

1. Flow through conduits: A fully developed laminar or turbulent transfer of air, gas, etc. occurs
in conduits with well-defined geometry and surface properties, for example, flow of air and
toxic gases in mine airways.
2. Flow through broken workings: Flow through broken workings can be laminar or turbulent
depending on the degree of consolidation of the broken strata and the pressure difference
across the area. In general, it is regarded as being laminar, for example, flow of methane
and air through gobs (mined out areas).
3. Flow through porous media: An example of this kind of flow is the seepage of methane from
coal beds and adjacent strata in situ. This subject is discussed in detail by the author in a
recent publication [1].
Most of these flow problems can be solved for varying initial and boundary condi-
tions, which provide a very fertile and important area of research. Precedents for their

Advanced Mine Ventilation. https://doi.org/10.1016/B978-0-08-100457-9.00003-1
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