MINE2103 Mine Planing 1
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Transcript MINE2103 Mine Planing 1
Effect of intrinsic coal properties on selfheating rates
Dr Basil Beamish1 and Prof Ahmet Arisoy2
1Director
– Spontaneous Combustion Testing Laboratory,
The University of Queensland, Brisbane, Australia
2Faculty
of Mechanical Engineering, Istanbul Technical University, Istanbul, Turkey
Presentation Outline
Spontaneous combustion assessment strategy
Coal samples, equipment and testing
Self-heating curves for different coal ranks
Self-heating relationships
R70 vs RIT
Conclusions and future work
Strategy for assessing sponcom
propensity
Four stages of assessment
Stage I – Coal quality indexing
Stage II – Small-scale coal behaviour/nature
testing (UQ adiabatic oven)
Stage III – Bulk-scale coal response testing
(UQ 2-metre column)
Stage IV – Coal environment modelling
Indexing parameters
Assessment of coal spontaneous combustion
propensity has been limited to a variety of smallscale self-heating index tests
R70, CPT, SHTmin, IRH, TTR, RIT
Type of sample
core, face or stockpile
Age of sample
storage method (under water, under
nitrogen, frozen)
Suggate rank plot of coals studied
80
70
0
1
2
3
Volatile Matter (%, dmmsf)
NZ Coal
Band
4
60
10
9
5
6
7
8
11
50
12
13
40
14
0
30
5
15
20
10
16
14
17
18
10
19
20
25
0
16500
16000
15500
15000
14500
14000
13500
13000
12500
Calorific Value (Btu/lb, dmmsf)
12000
11500
11000
10500
10000
R70 Test procedure
150 g coal crushed to <212 micron
Dried under nitrogen at 110oC for at least 16h,
then cooled to 40oC
Transferred to thermos and stabilised under
nitrogen in adiabatic oven at 40oC ± 0.2oC
Flow switched to oxygen at 50 mL/min
Temperature change recorded by computer
R70 values determined as the average selfheating rate from 40oC to 70oC, expressed in
oC/h
Adiabatic oven exterior
Adiabatic oven interior
Reaction vessel housing
Adiabatic coal self-heating curves
for low to medium rank coals
140
o
Coal Temperature ( C)
160
120
100
80
60
40
0
1
2
3
4
5
6
7
8
9
10
Time (h)
Coal A (subC)
Coal B (subB)
Coal C (subA)
Coal D (hvCb)
Coal E (hvBb)
Coal F (hvBb)
Adiabatic coal self-heating curves
for high rank coals
140
o
Coal Temperature ( C)
160
120
100
80
60
40
0
20
40
60
80
100
120
140
160
180
Time (h)
Coal G (hvAb)
Coal H (hvAb)
Coal I (mvb)
Coal J (lvb)
200
220
240
R70 value determination
160
Temperature (oC)
140
120
100
80
R70 = 2.18 oC/h
60
40
0
2
4
6
8
10
12
14
Time (hours)
16
18
20
22
24
140
40
120
35
100
30
80
25
60
20
40
15
20
3
10
2
y = -0.0063x + 0.4255x - 9.1937x + 64.103
R2 = 0.9918
0
5
-20
0
2
4
6
8
10
12
Suggate rank
SHT
R70
14
16
18
R70 (oC/h, dmmf)
SHT (oC)
SHT values using original Smith
and Lazzara equation
Previous rating of R70 values
<0.5 oC/h low propensity
0.5-0.8 oC/h medium propensity
>0.8 oC/h high propensity
ratings set over 25 years ago based on
Queensland coals
currently mining a far greater range of
coals, particularly from the lower end of
the high volatile bituminous rank
Current rating of R70 values for
NSW coals
R70 < 1.0 oC/h low (Class I)
1.0 ≤ R70 < 2 oC/h low - medium (Class II)
2 ≤ R70 < 4 oC/h medium (Class III)
4 ≤ R70 < 8 oC/h high (Class IV)
8 ≤ R70 < 16 oC/h very high (Class V)
16 ≤ R70 < 32 oC/h ultra high (Class VI)
≥ 32 oC/h extremely high (Class VII)
Current rating of R70 values for
QLD coals
R70 < 0.5 oC/h low (Class I)
0.5 ≤ R70 < 1 oC/h low - medium (Class II)
1 ≤ R70 < 2 oC/h medium (Class III)
2 ≤ R70 < 4 oC/h high (Class IV)
4 ≤ R70 < 8 oC/h very high (Class V)
8 ≤ R70 < 16 oC/h ultra high (Class VI)
≥ 16 oC/h extremely high (Class VII)
Relationship between R70 and ash
content for hvb coals
8.00
7.00
H
R70 (oC/h, db)
6.00
5.00
4.00
M
3.00
2.00
LM
1.00
L
0.00
0
5
10
15
20
25
30
35
40
45
50
Ash content (%, db)
Seam A (hvCb)
Seam B (hvBb)
Seam C (hvBb)
Seam F (hvAb)
Seam G (hvAb)
Seam H (hvAb)
Seam D (hvBb)
Seam E (hvAb)
Recent mine-site review for a NSW
longwall operation
8.00
7.00
R70 (oC/h, db)
6.00
High
5.00
4.00
Medium
3.00
2.00
Low - Medium
1.00
Low
0.00
0
5
10
15
20
25
30
35
40
45
Ash content (%, db)
Coal A (hvCb)
Coal E (hvAb)
Coal I (hvAb)
MG6 2HDG 5-6C/T
Coal B (hvBb)
Coal F (hvAb)
Coal J (mvb)
MG6 1-2HDG 24C/T
Coal C (hvBb)
Coal G (hvAb)
MG1 2HDG 12-13C/T
Coal D (hvBb)
Coal H (hvAb)
LW6 #4 Chock 18-19C/T
50
Relationship between R70 and RIT
for Sydney Basin coals
180
Decreasing
propensity
170
RIT (oC)
160
150
140
Increasing
propensity
130
120
110
100
0
1
2
3
4
5
6
7
8
9
10
11
R70 (oC/h)
Coal A (hvCb)
Coal E (hvAb)
Coal I (hvAb)
MG6 2HDG 5-6C/T
Coal B (hvBb)
Coal F (hvAb)
Coal J (mvb)
MG6 2HDG 24-25C/T
Coal C (hvBb)
Coal G (hvAb)
MG1 2HDG 12-13C/T
Coal D (hvBb)
Coal H (hvAb)
LW6 #4 Chock 18-19C/T
12
Two coals with the same R70 selfheating rate
160
Temperature ( oC)
140
120
100
80
60
40
0
5
10
15
20
25
Time (hours)
high volatile bituminous (18.0% ash, db)
subbituminous (54.3% ash, db)
30
Conclusions and future work
Defining site specific relationships for coal self-heating
rates helps to identify and explain possible propensity
variations between mines and within the same mine
Using a combined low temperature and high temperature
index system (R70 vs RIT) can provide a more accurate
assessment of spontaneous combustion propensity that
enables mining analogues to be clearly identified
The UQ database now covers a wide range of Australian,
New Zealand, Indonesian and US coals
New mining areas from the Surat, Galilee and Gunnedah
Basins in Australia will be added to the UQ database over
the next six months