Title: A database of ventilation friction factors for Canadian underground mines
1A database of ventilation friction factors for
Canadian underground mines
Kostas Fytas, professor Charles Gagnon,
graduate student Department of Mining,
Metallurgical and Materials Engineering Laval
University, Quebec City
June, 2008
2K factor
- Empirical friction factor expressing friction
losses
- Very important in simulations of ventilation
networks
- It can be computed from Atkinsons formula
- K friction factor K (Kg/m³)
- H pressure drop measured underground (Pa)
- A area of airway (m²)
- L length of airway (between two measuring
points) (m) - P perimeter of airway (m)
- V air velocity (m /s)
3Previous work
4Problem
- Many ventilation engineers still use the K
factors by McElroy (1935) - McElroy measured them in the following
conditions - small openings (2-6 m2), extremely rough rock
surfaces - obstacles (rail transport), timber supported
- not representative of modern conditions
- Modern conditions
- much larger openings (10-15m2), better drilling
blasting methods, smoother walls, supported by
rockbolts or shotcrete - Measuring K factors is tedious requires
expensive equipment
5Objectives of database of K factors
- To help ventilation planners to better estimate K
factors according to specific conditions - Create a database of K factors a search engine
that is - user friendly
- rapid
- integrated images (to characterize wall
roughness) - drilling patterns
- detailed description of local conditions
6Ventilation survey
- The following mines participated in the project
- Beaufor (Val-Senneville),
- Bell-Allard (Matagami),
- Bouchard-Hébert (Rouyn-Noranda),
- Doyon, (Rouyn-Noranda),
- Géant-Dormant (Amos),
- Laronde (Cadillac),
- Louvicourt (Louvicourt),
- Mouska (Rouyn-Noranda),
- Niobec (St-Honoré),
- Raglan (Katinniq)
7- K friction factor (Kg/m³)
- H pressure drop (Pa)
- A area of airway (m²)
- L length of airway (m)
- P perimeter of airway (m)
- V air velocity (m /s)
8- Calculation of head losses (H)
- H is calculated from Bernouillis equation
(energy conservation) - ? Heads at point 1 ? Heads at point 2 losses
- HS1 HZ1 HV1 HS2 HZ2 HV2 Losses
- HS1 et HS2 statique heads
- HZ1 et HZ2 potential heads
- HV1 et HV2 velocity heads
1
2
9- Dry and wet bulb temperatures (ts , th)
Psychrometric properties of mine air
Sling psychrometer
Air density (?) and Relative humidity (?)
- K factor standardization
- Specific K factor (Ks)
- Standardised K factor (KN)
KN KS ?air Nm/?air in-situ
10- Two modern SETRA 370 altimeters were used
- Resolution of 1 foot or 3,59 Pascal
- Precision of 0,02.
11- Area (A) and perimeter (P) of section
Photography
Digitization
12Distance between 2 points (L)
Resolution of 1 cm and precision of 0,1.
13- Anemometer Extech instrument
- Resolution of 1 m/sec
- Precision of 1.
- Continuous traversing of section
14- Minimal measuring conditions
361 K factors were measured ? 139 were retained
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16RESULTS
17 18- Small vein deposits
- openings of 2-2,5m x 2-2,5m
19 20 211 - Conventional
2 - Alimak
3 Raise boring
22Typical K factors
23Comparison of our K factors with those of Prosser
Wallace
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26Example of photos
27Example of photos
28Example of photos
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30CONCLUSIONS
- K factors are very important in ventilation
network simulations - K factors are difficult to measure
- A user friendly database with built in
photographs - The database allows the rapid estimation of K
factors with a good precision - The use of photographs allows the user to
estimate K factors according to his specific
conditions - The database can be used to do
- Ventilation planning of a new mine
- Ventilation planning of an existing mine
31Acknowledgements
- The following mines that participated in the
project - Beaufor (Val-Senneville), Bell-Allard
(Matagami), Bouchard-Hébert (Rouyn-Noranda),
Doyon, (Rouyn-Noranda), Laronde (Cadillac),
Louvicourt (Louvicourt), Géant-Dormant (Amos),
Mouska (Rouyn-Noranda), Niobec (St-Honoré),
Raglan (Katinniq). - IRSST
- Quebec Mining Association (AMQ)