based on the experience of hydraulic fracture techniques ... · pdf filecablebolting chainlink...

Copyrights© 2015 CODELCO-CHILE. Todos los Derechos Reservados. | Copyrights© 2015 by CODELCO-CHILE. All Rights Reserved.

Selection of Exploitation Method Based on the Experience of Hydraulic Fracture Techniques at the El Teniente Mine

May 2016

Authors: Cesar Pardo Eduardo Rojas

Copyrights© 2015 CODELCO-CHILE. Todos los Derechos Reservados. | Copyrights© 2015 by CODELCO-CHILE. All Rights Reserved. Copyrights© 2015 CODELCO-CHILE. Todos los Derechos Reservados. | Copyrights© 2015 by CODELCO-CHILE. All Rights Reserved. 2

• El Teniente Overview

• Lessons Learned from Exploitation of Primary Ore

• Evolution of Panel Caving in Primary Ore

• Reflections

Content

Copyrights© 2015 CODELCO-CHILE. Todos los Derechos Reservados. | Copyrights© 2015 by CODELCO-CHILE. All Rights Reserved. Copyrights© 2015 CODELCO-CHILE. Todos los Derechos Reservados. | Copyrights© 2015 by CODELCO-CHILE. All Rights Reserved.

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.


Overview El Teniente Mine Isometric view

Abrupt topography (more than 1km difference between the lowest and highest part of the mountain).

Influence of tectonic

Copyrights© 2015 CODELCO-CHILE. Todos los Derechos Reservados. | Copyrights© 2015 by CODELCO-CHILE. All Rights Reserved. 5

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

Copyrights© 2015 CODELCO-CHILE. Todos los Derechos Reservados. | Copyrights© 2015 by CODELCO-CHILE. All Rights Reserved. Copyrights© 2015 CODELCO-CHILE. Todos los Derechos Reservados. | Copyrights© 2015 by CODELCO-CHILE. All Rights Reserved. 6 Stockwork Andesita Hw (Esmeralda Mine)

Brecha Braden

Overview El Teniente Mine - Geology

RQD= 90-100

GSI= 80-100

UCS= 120-150


Overview El Teniente Mine – Premining Stress

1

3


Lessons Learned from Exploitation of Primary Ore


Lessons Learned from Exploitation of Primary Ore Hidrofracturing concept


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


Lessons Learned from Exploitation of Primary Ore Results of Implementation Hidrofracturing


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


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


Stiffener plates

Lessons Learned from Exploitation of Primary Ore Evolution of Drawpoint support


15

Evolution of Panel Caving in Primary Ore


• 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)


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)


• 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)


Undercut cantilever beam

Cantilever beam length (m)

Ab

utm

ent

stre

ss in

ten

sity

fac

tor


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


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)


• 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)


100m bajo UCL y 170m Sobre UCL

Case example: Esmeralda


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 > 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 > 2.6

Section view: (a) Pre & advance undercut , (b) post undercut with HF.

Case example: Esmeralda - Seismic response


25

Case example: Esmeralda - Undercut drift damage

Advance undercut Post undercut with HF


Post Undecut (T 4 Sur) Post Undercut with FH (Esmeralda)

26

Case example: T4 Sur - Esmeralda / drawpoint damage


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


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


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


Thank you

Questions?

30

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