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A database of ventilation friction factors for Canadian underground mines

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Title: A database of ventilation friction factors for Canadian underground mines


1
A 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
2
K factor
  • Empirical friction factor expressing friction
    losses
  • Includes shock 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)

3
Previous work
4
Problem
  • 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

5
Objectives 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

6
Ventilation 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 factor measurement
  • 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
  • Pressure survey (H)
  • 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
  • Precision of 1 to 2

12
Distance between 2 points (L)
Resolution of 1 cm and precision of 0,1.
13
  • Air velocity (V)
  • 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
15
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16
RESULTS
  • Statistics
  • Search engine

17
  • Regular airways

18
  • Small airways
  • Small vein deposits
  • openings of 2-2,5m x 2-2,5m

19
  • Inclined haulage drifts

20
  • Spiral ramps

21
  • Ventilation raises

1 - Conventional
2 - Alimak
3 Raise boring
22
Typical K factors
23
Comparison of our K factors with those of Prosser
Wallace

24
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25
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26
Example of photos
27
Example of photos
28
Example of photos
29
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30
CONCLUSIONS
  • 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

31
Acknowledgements
  • 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)
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