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