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Selection of Exploitation Method Based on the Experience of Hydraulic Fracture Techniques at the El Teniente Mine
May 2016
Authors: Cesar Pardo Eduardo Rojas
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• El Teniente Overview
• Lessons Learned from Exploitation of Primary Ore
• Evolution of Panel Caving in Primary Ore
• Reflections
Content
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3
Overview Codelco Chile - El Teniente Division
The biggest underground copper mine in the world, in operation since 1905.
More than 110 million tonnes of copper in geological resources, and 36 million tonnes of copper in ore reserves.
Current Production Rate: 140 ktpd
An integrated complex: Mine - Plant - Smelter facilities.
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Overview El Teniente Mine Isometric view
Abrupt topography (more than 1km difference between the lowest and highest part of the mountain).
Influence of tectonic
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Tonalita
Dacita
Quebrada Teniente Crater
NBraden Pipe
1° - 2° contacto
Level 1200m
Level 1500m
Level 1983 (Ten-8)
3700 msl
Overview El Teniente Mine - Geology
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Brecha Braden
Overview El Teniente Mine - Geology
RQD= 90-100
GSI= 80-100
UCS= 120-150
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Overview El Teniente Mine – Premining Stress
1
3
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Lessons Learned from Exploitation of Primary Ore
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Lessons Learned from Exploitation of Primary Ore Hidrofracturing concept
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The HF is formed in the major and intermediate principal stress plane.
Circular shape assumed for design purpose (20m radius after a 30 min)
Tensile Failure mode
HF spacing 1.5m.
Lessons Learned from Explotation of Primary Ore Hydraulic fracture features and its conceptualisation
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Lessons Learned from Exploitation of Primary Ore Results of Implementation Hidrofracturing
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0.00
0.80
1.60
2.40
3.20
0
5
10
15
20
25
30
35
40
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
E
v
e
n
t
M
a
g
n
i
t
u
d
e
K
T
P
D
Year
Maximum Events Magnitude vs. Extraction Rates
Extraction Rates Max Magnitude 60<UCL<100 Max Magnitude HF above UCL (up to 100m)
UCL 2120 msnm.
NP 2102 msnm.
PA RENOColumna
PA RENOFalla G
100 m
ACARREO 2064 msnm.
Sobre PA
ColumnaPA
Bajo PA
PA Bajo NPFalla G
15 m
60 m
Polígono de control RENO
100 m
Elevation 2120
Elevation 2102
Elevation 2064
UCL 2120 msnm.
NP 2102 msnm.
PA RENOColumna
PA RENOFalla G
100 m
ACARREO 2064 msnm.
Sobre PA
ColumnaPA
Bajo PA
PA Bajo NPFalla G
15 m
60 m
Polígono de control RENO
100 m
60 m
Elevation 2120
Elevation 2102
Elevation 2064
60 m
Lessons Learned from Exploitation of Primary Ore Results of Implementation Hidrofracturing
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13
0
10
20
30
40
50
60
70
0
25
50
75
100
125
150
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
# E
stal
lidos
de
Roc
as
KT
PD
Estallidos de Rocas v/s Producción años 1982 a 2015
Producción Primario Pilar Norte Ten-3 Isla Martillo Isla LHD Esmeralda Ten Sub-6 Ten-4 Sur
Bolts L Plate Welded Mesh Shotcrete2 Kj/m2
Cablebolting
Chainlink mesh 5 Kj/m2
Face support
Reduction shotcrete thickner over the mesh
Second pass mesh
Bolt 25 mm
Rhomboid mesh >12 Kj/m2
Mesh to the face
AMJ
Lessons Learned from Exploitation of Primary Ore Evolution of ground support system
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Stiffener plates
Lessons Learned from Exploitation of Primary Ore Evolution of Drawpoint support
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15
Evolution of Panel Caving in Primary Ore
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• One or two drawbell ahead of the undercut front. Blast undercut on top of the drawbell.
• The abutment stresses affected the crown pillar with a medium to high intensity factor. Impacting on the drawbell incorporation.
Factor Intensidad Abutment Stress
FI = abutment / in-situ
> 4
3 - 4
< 3
Frente
Hundimiento
NH
NP
Evolution of Panel Caving in Primary Ore Panel Caving, Post Undercutting sequence (1982 -2010)
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The productive area availability was about 50% (mainly due to orepass damage and rorkburst and collapses afecting the extraction level). Drawpoints rehabilitation reached up to 25%.
Damage at Ore pass (production: 350.000 ton)
Collapses T4 SUR Damage at Drawpoint
Evolution of Panel Caving in Primary Ore Panel Caving, Post Undercutting sequence (1982 -2010)
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• Undercut a beam (Low and flat) of 60m long to provide stress shadow to the extraction level.
• Development of the extraction level drives and drill and blast of the drawbells under the stress shadow.
• Abutment stress zone ahead of the caving front produced a very high intensity factor (over 4 ) on the undercut level.
18
Frente
ExtracciónFrente
Hundimiento
Evolution of Panel Caving in Primary Ore Panel Caving, Pre Undercutting sequence (1997 -2005)
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Undercut cantilever beam
Cantilever beam length (m)
Ab
utm
ent
stre
ss in
ten
sity
fac
tor
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Remnant pillars caused by loss of changing holes- These remnant pillars transferred load to extraction level resulting in collapses. Lack of operational flexibility, i.e Development is highly dependent on undercut rate.
Remnant pillar Drawpoint damage
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NP
• Undercut a beam (Low and flat) of 60m long to provide stress shadow to the extraction level.
• Development of the extraction level drives independent of the undercut front.
• Drawpoint connection and drawbells construction under the stress shadow.
• Abutment stress zone ahead of the caving front produced a very high intensity factor (over 4 ) on the undercut level.
• Similar issues experienced in the pre undercut variant
Evolution of Panel Caving in Primary Ore Panel Caving, Advanced Undercutting sequence (2004 -2014)
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• Rock mass preconditioning by hydraulic fracturing ahead of the undercut front (>=100).
• One or two drawbell ahead of the undercut front. Blast undercut on top of the drawbell.
• The abutment stresses affected the crown pillar with a medium to high intensity factor. Impacting on the drawbell incorporation.
Post Undercut with FH
22
Fracturas FH
Pozo FH
Fracturas FH
Pozo FH
Evolution of Panel Caving in Primary Ore Panel Caving, Post Undercutting with HF (2010 -2015)
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100m bajo UCL y 170m Sobre UCL
Case example: Esmeralda
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2120
2140
2160
2180
2200
2220
2240
2260
2280
2300
2320
2340
2360
2380
09-0
8-19
95
08-1
0-19
95
07-1
2-19
95
05
-02
-19
96
05
-04
-19
96
04
-06
-19
96
03
-08
-19
96
02-1
0-19
96
01-1
2-19
96
30-0
1-19
97
31
-03
-19
97
30
-05
-19
97
29
-07
-19
97
27
-09
-19
97
26-1
1-19
97
25-0
1-19
98
26-0
3-19
98
25
-05
-19
98
24
-07
-19
98
22
-09
-19
98
21
-11
-19
98
20-0
1-19
99
21-0
3-19
99
20-0
5-19
99
19
-07
-19
99
17
-09
-19
99
16
-11
-19
99
15
-01
-20
00
15-0
3-20
00
14-0
5-20
00
13-0
7-20
00
11
-09
-20
00
10
-11
-20
00
09
-01
-20
01
10
-03
-20
01
09-0
5-20
01
08-0
7-20
01
06-0
9-20
01
05
-11
-20
01
04
-01
-20
02
Magnitud 0,6 a 0,9 Magnitud 1,0 a 1,5 Magnitud 1,6 a 1,9 Magnitud 2,0 a 2,5 Magnitud 2,6 a 2,9
UCL
NP
Acarreo
Socavación Incorporación de bateas y socavación
Caving en RégimenInicio de Caving2120
2140
2160
2180
2200
2220
2240
2260
2280
2300
2320
2340
2360
2380
17
-04
-20
11
17
-05
-20
11
16
-06
-20
11
16
-07
-20
11
15
-08
-20
11
14
-09
-20
11
14
-10
-20
11
13
-11
-20
11
13
-12
-20
11
12
-01
-20
12
11
-02
-20
12
12
-03
-20
12
11
-04
-20
12
11
-05
-20
12
10
-06
-20
12
10
-07
-20
12
09
-08
-20
12
08
-09
-20
12
08
-10
-20
12
07
-11
-20
12
07
-12
-20
12
06
-01
-20
13
05
-02
-20
13
07
-03
-20
13
06
-04
-20
13
06
-05
-20
13
05
-06
-20
13
05
-07
-20
13
04
-08
-20
13
03
-09
-20
13
03
-10
-20
13
02
-11
-20
13
02
-12
-20
13
01
-01
-20
14
31
-01
-20
14
02
-03
-20
14
01
-04
-20
14
01
-05
-20
14
31
-05
-20
14
30
-06
-20
14
30
-07
-20
14
Magnitud 0,6 - 0,9 Magnitud 1 a 1,5 Magnitud 1,6 a 1,9 Magnitud 2,0 a 2,5
UCL
NP
Acarreo
Caving en RégimenInicio de Caving
Magnitud < 0.9
Magnitud 1.0 – 1.5
Magnitud 1.6 – 1.9
Magnitud 2.0 – 2.5
Magnitud > 2.6
(a) Esmeralda Tradicional: Hundimiento Previo sin FH (b)Esmeralda Bloque 1: Hundimiento Convencional con FH
Proceso de conexiónProceso de
conexión
Magnitud < 0.9
Magnitud 1.0 – 1.5
Magnitud 1.6 – 1.9
Magnitud 2.0 – 2.5
Magnitud > 2.6
Section view: (a) Pre & advance undercut , (b) post undercut with HF.
Case example: Esmeralda - Seismic response
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25
Case example: Esmeralda - Undercut drift damage
Advance undercut Post undercut with HF
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Post Undecut (T 4 Sur) Post Undercut with FH (Esmeralda)
26
Case example: T4 Sur - Esmeralda / drawpoint damage
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Global Results Rock burst
27
0
10
20
30
40
50
60
70
0
25
50
75
100
125
150
198
2
198
3
198
4
1985
198
6
198
7
198
8
198
9
199
0
199
1
199
2
199
3
199
4
199
5
199
6
199
7
199
8
199
9
200
0
200
1
200
2
200
3
200
4
200
5
200
6
2007
2008
200
9
201
0
201
1
201
2
201
3
201
4
201
5
N°
Esta
llid
os d
e R
ocas
KT
PD
AÑO
Estallidos de Rocas v/s Producción años 1982 a Diciembre de 2015
Producción Primario
Pilar Norte
Ten-3 Isla Martillo
Isla LHD
Esmeralda
Ten Sub-6
Ten-4 Sur
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0
5
10
15
20
25
0
25
50
75
100
125
150
19
82
19
83
19
84
19
85
19
86
19
87
19
88
19
89
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
20
09
20
10
20
11
20
12
20
13
20
14
20
15
Are
a C
ola
psad
a (
m2/1
000)
KT
PD
AÑO
Area Colapsada v/s Producción años 1982 a Diciembre de 2015
Producción Primario
Ten-4 Sur
Ten Sub-6
Esmeralda
Regimiento
Global Results Collapses
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The success of a mining method relies on a
robust design accompanied of a implementation and operation stages that follows the desing.
The mining method should be easily
implemented by the operators. The engenineering stage should provide
clear rules to be followed during the operation.
The mining method need to allow for
flexibility should change in geotechnical conditions, technology and safety practices occurs.
Reflexions