Chapter 8
Secondary Ventilation
8.1 Introduction
Secondary, auxiliary, or ancillary ventilation conveys air to those parts of the mine
that are not directly served by the main ventilation circuit, such as development headings and certain stopes. The calculations we explore here recur in many engineering
situations, not only in mining but also in civil works, for example, tunnel construction. The ultimate aim of these calculations is to generate a value for the necessary
rate of air renewal within the mining works in order to dimension the appropriate
fan. To this end, an extensive bibliography concerning the existing methodologies is
compiled in this chapter.
8.2 Types of Secondary Ventilation
8.2.1 Forcing Ventilation
This type of ventilation pushes fresh air onto the gallery face. It has the following
main characteristics:
• It favours the removal of the gases at the active face.
• It decreases the re-entry time after blasting.
• The air carried to the face is relatively fresh.
• The exhaust gases return through the gallery with the associated disadvantages.
• Dust is forced into suspension and dispersed by turbulence.
Depending on the number of fans and their arrangement, the forcing system can
be single (Fig. 8.1a), double (Fig. 8.1b) or multiple (Fig. 8.1c).
The cone of air leaving the ventilation duct spreads out as it approaches the active
face and as it does so its velocity decreases. Referring to Fig. 8.2, this generates
a stationary zone, termed the dead zone (a) and a ventilated zone (X). In order to
© The Editor(s) (if applicable) and The Author(s), under exclusive license
to Springer Nature Switzerland AG 2020
C. Sierra, Mine Ventilation, https://doi.org/10.1007/978-3-030-49803-0_8
285
Secondary Ventilation
8.1 Introduction
Secondary, auxiliary, or ancillary ventilation conveys air to those parts of the mine
that are not directly served by the main ventilation circuit, such as development headings and certain stopes. The calculations we explore here recur in many engineering
situations, not only in mining but also in civil works, for example, tunnel construction. The ultimate aim of these calculations is to generate a value for the necessary
rate of air renewal within the mining works in order to dimension the appropriate
fan. To this end, an extensive bibliography concerning the existing methodologies is
compiled in this chapter.
8.2 Types of Secondary Ventilation
8.2.1 Forcing Ventilation
This type of ventilation pushes fresh air onto the gallery face. It has the following
main characteristics:
• It favours the removal of the gases at the active face.
• It decreases the re-entry time after blasting.
• The air carried to the face is relatively fresh.
• The exhaust gases return through the gallery with the associated disadvantages.
• Dust is forced into suspension and dispersed by turbulence.
Depending on the number of fans and their arrangement, the forcing system can
be single (Fig. 8.1a), double (Fig. 8.1b) or multiple (Fig. 8.1c).
The cone of air leaving the ventilation duct spreads out as it approaches the active
face and as it does so its velocity decreases. Referring to Fig. 8.2, this generates
a stationary zone, termed the dead zone (a) and a ventilated zone (X). In order to
© The Editor(s) (if applicable) and The Author(s), under exclusive license
to Springer Nature Switzerland AG 2020
C. Sierra, Mine Ventilation, https://doi.org/10.1007/978-3-030-49803-0_8
285