Transcript Slide 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
K factor
• Empirical friction factor expressing friction losses
• Includes shock losses
• Very important in simulations of ventilation networks
• It can be computed from Atkinson’s formula :
• K friction factor K (Kg/m³)
HA
K
LPV ²
• 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)
Previous work
Author
Country
Date
No. of K
Conditions
Murgue
France
1893-94 (4)
Small openings
McElroy
USA
1930
(144)
Timbered small openings (26 m2), mostly rough walls
Frost
USA
1946
(3)
Small openings
Romensky
Soviet Union 1969
(6)
Large openings
Gangal et
Notley
Canada
1985
(12)
Large openings, igneous
rocks
U.Laval
(Billette, Fytas,
Garant)
Canada \
Québec
1984
1988
(42)
Small & large openings
McPherson
USA
1993
(18)
Large openings
Prosser et
Wallace
USA
1999
(12)
Large openings
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
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
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)
 K factor measurement
HA
K 
LPV ²
•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)
 Calculation of head losses (H)
H is calculated from Bernouilli’s equation (energy conservation):

1
2
 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

 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
Pressure survey (H)
 Two modern SETRA 370 altimeters were used
 Resolution of 1 foot or 3,59 Pascal
 Precision of 0,02%.
 Area (A) and perimeter (P) of section
Photography
 Precision of 1% to 2%
Digitization
Distance between 2 points (L) :
Resolution of 1 cm and precision of 0,1%.
Air velocity (V)
• Anemometer Extech instrument
• Resolution of 1 m/sec
• Precision of 1%.
• Continuous traversing of section
Minimal measuring conditions
1 - V > 2 m/s
2 - L > 40 m
3 – No air loss
361 K factors were measured
→ 139 were retained
 Variables
• Support type
• Wall roughness, drilling pattern
• Curvature
• Obstacles
 The database is an empirical tool to estimate K factors
according to specifique conditions
 The database can be used to do :
1. Ventilation planning of a new mine
2. Ventilation planning of an existing mine
RESULTS
 Statistics
 Search engine
 Regular airways
Mean value
Max value
Min value
Standard
deviation
No of values
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
#
97
239
16
51,8
45
Histogram of K factors in regular airways
14
No of K factors
12
10
8
6
4
2
0
[0-25[
[25-50[
[50-75[
[75-100[ [100-125[ [125-150[ [150-175[ [175-200[ [200-225[ [225-250[
Intervals (Kg/m³)
 Small airways
Mean value
Max value
Min value
Standard
deviation
No of values
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
#
95
223
20
50
28
• Small vein deposits
• openings of 2-2,5m x 2-2,5m
No. of K factors
Histogram of K factors in small airways
8
7
6
5
4
3
2
1
0
[0-25[
[25-50[
[50-75[
[75-100[ [100-125[ [125-150[ [150-175[ [175-200[ [200-225[
Intervals (Kg/m³)
 Inclined haulage drifts
Mean value
Max value
Min value
Standard
deviation
No of values
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
#
112
257
30
59
34
Histogram of K factors in inclined haulage drifts
7
No of K factors
6
5
4
3
2
1
0
[0-25[
[25-50[ [50-75[ [75-100[
[100125[
[125150[
[150175[
Intervals (Kg/m³)
[175200[
[200225[
[225250[
[250275[
 Spiral ramps
Mean value
Max value
Min value
Standard
deviation
No of values
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
#
187
279
40
72
16
Histogram of K factors in spiral ramps
No of K factors
5
4
3
2
1
0
[0-25[ [25-50[ [50-75[
[75100[
[100125[
[125150[
[150175[
[175200[
Intervals (Kg/m³)
[200225[
[225250[
[250275[
[275300[
 Ventilation raises
Mean value
Max value
Min value
Standard
deviation
No of values
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
#
132
359
15
99
14
1 - Conventional
2 - Alimak
3 – Raise boring
Histogram of K factors in ventilation raises
No of K factors
3
2
1
0
[0-25[ [2550[
[5075[
[75- [100- [125- [150- [175- [200- [225- [250- [275- [300- 325+
100[ 125[ 150[ 175[ 200[ 225[ 250[ 275[ 300[ 325[
Intervals (Kg/m³)
Typical K factors
Regular airway
Mean value
Max value
Min value
Standard deviation
No of values
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(#)
107
151
59
32
13
Mean value
Max value
Min value
Standard deviation
No of values
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(#)
97
144
46
34
10
Mean value
Max value
Min value
Standard deviation
No of values
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(#)
96
146
59
29
6
Mean value
Max value
Min value
Standard deviation
No of values
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(Kg/m3) X 10-4
(#)
221
278
150
42
9
Small airway
Inclined
haulage drifts
Spiral ramp
Example of photos
Example of photos
Example of photos
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
Acknowledgements
 The following mines that participated in the project :
 Beaufor (Val-Senneville), Bell-Allard (Matagami),
Bouchard-Hébert (Rouyn-Noranda), Doyon, (RouynNoranda), Laronde (Cadillac), Louvicourt (Louvicourt),
Géant-Dormant (Amos), Mouska (Rouyn-Noranda),
Niobec (St-Honoré), Raglan (Katinniq).
 IRSST
 Quebec Mining Association (AMQ)