Transcript KAINANTU UNDERGROUND MINE STOPE VENTILATION MEASUREMENT

KAINANTU UNDERGROUND
MINE STOPE VENTILATION
MEASUREMENT USING TRACER
GAS AND NUMERICAL
SIMULATION
Gabriel ARPA, Kyuro SASAKI and Yuichi SUGAI
Department of Earth Resources Engineering,
Faculty of Engineering, Kyushu University, Fukuoka 812-8581,
Japan
BACKGROUND
Continuous research into improving airflow quality and quantity
is an on going activity. Tracer gas can be an effective method to
assess mine ventilation system.
Tracer gas can be used to:
Determine complex airflow patterns and flow volume, where
velocity is too low, openings too large, or cross section
geometry too complex.
Accurate determination of ventilation assessment parameters;
Re-circulations, - Leakages, -residence time
Simulate and model the spread of contaminants.
Tracer gas can give effective information of airflow in
highly irregular airflow paths and can be an effective
method to assess mine ventilation system and airflow
dynamics.
REVIEW
1.Check for air
Leakage. (Hardcastle
2. Check for
there is little research on
possible shortHowever,
cutset al. 1993)
3./leakages
Flow dynamics
(Widodo
shorter mine airways and mine face,
along
et al. airway
2006) and the effect of dead ends and open
routes. (Taylor et
spaces along airway routes.
al. 1953, Sasaki
et al. 2002,
Widodo et al.
2006)
OBJECTIVE
To Study:
Airflow through narrow vein shrinkage stope by using
tracer gas technique and numerical simulation.
The effect of dead end drives, openings and empty spaces
along the airway route on airflow quantity and quality.
METHOD
By pulse injection of SF6 from upstream positions
and measure the concentration with elapsed time at a
downstream position.
RESEARCH APPROACH
Ventilation Survey
Tracer Gas Measurement
Numerical Simulation
FIELD MEASUREMENT
The Kainantu Mine
Madang
Lae
KAINANTU MINE OVERVIEW
Mining Method: Narrow Vein Shrinkage stope
Production:
300 ton ore/day
Semi-mechanized operation
MINE VENTILATION
Ascension – Through flow system
Fan 1
4th Outlet
P (Pa)
Q (m3/s)
Fan 2
4th Outlet
Fan3
4th Outlet
500
400
400
３５
２５
２５
Schematic of ventilation system
Fan 3
Fan 2
Fan 1
4th Outlet
Main intake (1300 Portal)
MEASUREMENT SYSTEM
Gas Monitor system
Lap top
Stop watch
Portable scale
Balloons
Sulfur hexafluoride (SF6)
Lap top
Monitor
Sampling
Photoacoustic gas monitor
(Brual & Kjear 1302)
Upper level
Resolution = 10 ppb
Raise
Absolute accuracy = +/- 50 ppb
Sampling rate = 40 sec
Pulse release of SF6
Lower level
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MEASUREMENT PROCEDURE
SF6 monitoring point
Level 19
Drives
Raise 2
Raise 1
(No break through)
3m
4m
30 m
SF6 Release point.
Broken ore
25 m
Level 20
Raises
1m
４0 m
1m
30 m
SF6 release and measurement stope 20L20R ( Shrinkage stope)
SF6 measurement point
Level 19
Raise 1
Raise 2
SF6 Release
point.
30 m
Broken ore
15 m
Level 20
70 m
30 m
SF6 release and measurement stope 20L24R ( Shrinkage stope)
NUMERICAL SIMULATION
(Sasaki & Dindiwe, 2002)

2

Ci 1 ( ) Qi
X  vt   
Ci (t )  
exp 
1/ 2
4 Ex t   
0 2 AE x t   

t
 d

Where:
Ci
gas concentration at a downstream node
Ci-1
gas concentration at an upstream node
t
elapsed time from gas injection
Qi
air flow rate on an airway
τ
time interval
A
cross sectional area of an airway
Ex
effective turbulent diffusion coefficient in flow direction
X
distance between two nodes and
ν
average gas convection velocity in an airway
Downstream
Ci
Upstream
Ci-1
Airflow
EFFECT OF DEAD SPACES & OPENING ON AIRLOW
Airways with dead spaces
Airways without
dead spaces
Additional Route
Route 1
Time
Time
RESULTS
10.0
Measurement, 40 sec. interval
Simulated, route 1
Simulated, route 2
Sum. total flow (Route 1 & 2)
Simulated, route 3 (Open spaces)
Sum. total flow (Route 1, 2 & 3)
54 m3/min
8.0
SF6 conc. (ppm)
31 m3/min
6.0
6.3 m3/min
4.0
2.0
0.0
0
5
10
15
20
Time (mins)
25
30
SF6 monitoring
point
Level
Av. Velo.(m/s)
0.2-0.4
Raise
1-1.3
Level
19
Raise
2
Raise 1
(No break through)
30 m
SF6 Release
point.
Broken
ore
25 m
Level
20
Level
20
４0
m
30 m
SF6 release and measurement stope 20L20R ( Shrinkage stope)
35
RESULTS
8.0
SF6 conc. (ppm)
40.5 m3/min
Measurement 40 sec. interval
Simulated, route 1
Simulated ,route 2
Sum. total flow (Route 1 & 2)
Simulated, route 3 (Open spaces)
Sum. total flow (Route 1, 2 & 3)
6.0
4.0
27 m3/min
3.5 m3/min
2.0
0.0
0
5
10
15
Time (min.)
20
25
30
SF6 measurement
point
Level
19
Raise 1
Level
Av. Velo.(m/s)
0.2-0.4
Raise
1-1.3
SF6
Release
point.
Raise 2
Broken
ore
30 m
15 m
Level
20
70 m
70 m
30 m
30 m
SF6 release and measurement stope 20L24R ( Shrinkage stope)
35
RESULTS
20.0
Measurement, 40 sec. interval
Simulated, route 1
Simulated, route 2
Sum. total flow(Route 1 & 2)
Simulated, route 3(Open spaces)
Sum. total flow(Route 1, 2 & 3)
SF6 conc. (ppm)
16.0
34.5 m3/min
12.0
26 m3/min
8.0
2.5 m3/min
4.0
0.0
0
5
Time (min)
10
15
SF6 measurement
point
Level
19
Raise 1
Level
Av. Velo.(m/s)
0.2-0.4
Raise
1-1.3
SF6
Release
point.
Raise 2
Broken
ore
30 m
15 m
Level
20
30 m
30 m
SF6 release and measurement stope 19L16R ( Shrinkage stope)
RESULTS
10.0
Measurement, 40 sec. interval
Simulated, route 1
Simulated, route 2
Sum. total flow (Route 1 & 2)
Simulated, route 3 (Open spaces)
Sum. total flow (Route 1, 2 & 3)
SF6 conc. (ppm)
8.0
One Raise
Open
6.0
4.0
2.0
0.0
0
5
10
15
20
Time (mins)
25
30
35
SF6 conc. (ppm)
8.0
Measurement 40 sec. interval
Simulated, route 1
Simulated ,route 2
Sum. total flow (Route 1 & 2)
Simulated, route 3 (Open spaces)
Sum. total flow (Route 1, 2 & 3)
6.0
4.0
2.0
0.0
0
5
10
15
Time (min.)
20
25
30
35
20.0
Measurement, 40 sec. interval
Simulated, route 1
Simulated, route 2
Sum. total flow(Route 1 & 2)
Simulated, route 3(Open spaces)
Sum. total flow(Route 1, 2 & 3)
SF6 conc. (ppm)
16.0
12.0
8.0
4.0
0.0
0
5
Time (min)
10
15
Both Raise
Open
Better air flow in
the stope with
one raised, then
the stopes with
both raises open.
DISCUSSION and CONCLUSION
Better understanding of airflow routes can be achieved by studying
the arrival times and the peak of the concentration time curve for
the various routes simulated.
Airflow rates of the stopes were evaluated with matching measured
concentration-time curves with numerical ones by a numerical
diffusion model in considering diffusion in open and empty spaces
Most importantly, an additional airway branch was constructed. The
additional branch in the numerical model has a much longer airway
length and an increased cross-sectional area with low air flow velocity.
The new method has greatly improved the tailing effect .
Therefore it can be concluded that openings, dead end drives and other
open spaces have no relation on flow rates, but affect the airflow quality
provided from the inlet portal
END OF PRESENTATION!!!
THANK YOU VERY MUCH FOR YOUR
KIND ATTENTION!!!!!!!!!!
RESULTS
Additional airflow route to simulate for open spaces, dead end drive, voids etc..
Plan view, level 20
Raise 1
A
Raise 2
Level 20 drive
Airflow route 1
B
Airflow route 2
Airflow route 3.
Raise 1
Raise 2
(Dead end drives, voids and open spaces)
Raise
Raise
1
2
Level 20 drive
Schematic of airflow. A) Plan of 20 level, B) Arrangement of additional branch (Route 3)
SF6 monitoring
point
Level
19
Raise
2
Raise 1
(No break through)
30 m
SF6 Release
point.
Broken
ore
25 m
Level
20
４0
m
30 m
SF6 release and measurement stope 20L20R ( Shrinkage stope)
RESULTS
Additional airflow route to simulate for open spaces, dead end drive, voids etc..
Plan view, level 20
Raise 1
A
Raise 2
Level 20 drive
Airflow route 1
B
Airflow route 3.
Raise 1
(Dead end drives, voids and open spaces)
Raise
Airflow route 2
Raise 2
Raise
1
Level 20 drive
2
Schematic of airflow. A) Plan of 20 level, B) Arrangement of additional branch (Route 3)
SF6 measurement
point
Level
19
Raise 1
SF6
Release
point.
Raise 2
Broken
ore
30 m
15 m
Level
20
70
70 m
m
3030
mm
SF6 release and measurement stope 20L24R ( Shrinkage stope)
RESULTS
Additional airflow route to simulate for open spaces, dead end drive, voids etc..
Plan view, level 20
Raise 1
A
Raise 2
Level 20 drive
Airflow route 1
B
Airflow route 3.
Raise 1
(Dead end drives, voids and open spaces)
Raise
Airflow route 2
Raise 2
Raise
1
Level 20 drive
2
Schematic of airflow. A) Plan of 20 level, B) Arrangement of additional branch (Route 3)
SF6 measurement
point
Level
18
Raise 1
SF6
Release
point.
Raise 2
Broken
ore
30 m
15 m
Level
19
70
30 m
m
3030
mm
SF6 release and measurement stope 19L16R ( Shrinkage stope)
Airway
Route 1
Route 2
Route 3
1 -> 2
2 -> 3
3 -> 4
4 -> 5
1 -> 2
2 -> 6
6 -> 4
4 -> 5
1 -> 2
2 -> 13
13 -> 4
4 -> 5
Length
m
30
20
27
8
30
30
22
8
30
40
22
8
Tracer Gas Simulation
X-Area
Q
2
3
m
m /min
12
200
1
30
1
30
1
85
12
200
12
170
1
55
1
85
12
200
16
55
1
55
1
85
Velocity
m/s
0.28
0.5
0.5
1.42
0.28
0.24
0.92
1.42
0.28
0.06
0.92
1.42
Diff. Coef.
m 2 /s
0.75
0.75
0.75
0.75
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
Measured
Velocity
m/s
0.32
0.6
0.45
0.98
0.32
0.3
0.87
1.2
x
x
x
x
MIVENA
Velocity
m/s
0.33
0.58
0.5
1.5
0.33
0.32
0.91
1.24
x
x
x
x
Stope 20L20R
Airway
Rout 1
Route 2
Route 3
8 -> 9
9 -> 10
10 -> 11
11 -> 12
8 -> 9
9 -> 13
13 -> 11
8 -> 9
9 -> 14
14 -> 11
11 -> 12
Length
m
80
25
30
8
80
30
33
80
110
33
8
Tracer Gas Simulation
X-Area
Q
2
3
m
m /min
14
170
1.5
25
1.5
15
1.5
75
14
170
14
145
1.5
60
14
170
20
70
1.5
60
1.5
75
Stope 20L24R
Velocity
m/s
0.2
0.28
0.17
0.83
0.2
0.17
0.67
0.2
0.06
0.67
0.83
Diff Coef.
2
m /s
0.6
0.6
0.6
0.6
0.45
0.45
0.45
2
2
2
2
Measured
Velocity
m/s
0.26
0.31
0.2
0.85
0.26
0.21
0.7
x
x
x
x
MIVENA
Velocity
m/s
0.18
0.23
0.21
0.91
0.21
0.19
0.71
x
x
x
x
Most importantly, improvement has been made at the tailing effect
between the simulation and tracer gas measurement by reconstructing an
additional branch to represent the delayed arrival of air due to the open
spaces along the airways. The additional branch in the numerical model
has a much longer airway length and an increased cross-sectional area
with low air flow velocity. Therefore it can be concluded that openings,
dead end drives and other open spaces have no relation on flow rates, but
affect the airflow quality provided from the inlet portal.
10.0
Measurement, 40 sec. interval
Simulated, route 1
Simulated, route 2
Sum. total flow (Route 1 & 2)
Simulated, route 3 (Open spaces)
Sum. total flow (Route 1, 2 & 3)
SF6 conc. (ppm)
8.0
6.0
4.0
2.0
0.0
0
5
10
15
20
Time (mins)
25
30
SF6 monitoring
point
Level
19
Raise
2
Raise 1
(No break through)
30 m
SF6 Release
point.
Broken
ore
25 m
Level
20
４0
m
30 m
35
SF6 conc. (ppm)
8.0
Measurement 40 sec. interval
Simulated, route 1
Simulated ,route 2
Sum. total flow (Route 1 & 2)
Simulated, route 3 (Open spaces)
Sum. total flow (Route 1, 2 & 3)
6.0
4.0
2.0
0.0
0
5
10
15
Time (min.)
20
25
30
SF6 measurement
point
Level
19
Raise 1
SF6
Release
point.
Raise 2
Broken
ore
30 m
15 m
Level
20
70 m
30 m
35
20.0
Measurement, 40 sec. interval
Simulated, route 1
Simulated, route 2
Sum. total flow(Route 1 & 2)
Simulated, route 3(Open spaces)
Sum. total flow(Route 1, 2 & 3)
SF6 conc. (ppm)
16.0
12.0
8.0
4.0
0.0
0
5
Time (min)
10
15
SF6 measurement
point
Level
19
Raise 1
SF6
Release
point.
Raise 2
Broken
ore
30 m
15 m
Level
20
70 m
30 m
Taylor’s et al., 1953 & 1954
2

V
 ( x  ut ) 

c( x, t ) 
exp 

4
Dt
2 A Dt


Where:
C(x,t)
gas concentration at a downstream
V
Volume of gas released
t
elapsed time from gas injection
A
cross sectional area of an airway
D
Virtual diffusion coefficient in flow direction
X
distance between two nodes and
u
average uniform flow velocity of the airway
Airways with dead
spaces
Best Matching & Tailing Effect
Between Measured & Simulated
Airways without
dead spaces
Additional Route
Route 1
Measured
Simulated
Measured
Simulated
route 1
Simulated
additional route
Tailing Effect
Time
Time
VENTILATION NETWORK
20L20R
20L24R
19L16R
Construction of entire ventilation network
using Mine ventilation simulator, MIVENA
Ver.6 (Sasaki & Dindiwe, 2002)
Kainantu ventilation network (MIVENA)
Datadase window
Analysis window
Kainantu ventilation layout
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