thesis in-pit crushing as an alternative ubc_1988_a7 r32.pdf

8/11/2019 Thesis In-Pit Crushing as an alternative UBC_1988_A7 R32.pdf

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IN-PIT CRUSHING AND CONVEYING AS AN ALTERNATIVETO AN ALL TRUCK SYSTEM IN OPEN PI T MINES

by

JACEK K. RADLOWSKI

M . S c , The U n i v e r s i t y o f M i n i n g a nd M e t a l l u r g y , 1965Cracow, Po land

A THESIS SUBMITTED IN PARTI AL FU LFILLMENT

OF THE REQUIREMENTS FOR THE DEGREE

OF MASTER OF APPLIED SCIENCE

i n

THE FACULTY OF GRADUATE STUDIES

Depar tmen t o f M i n i n g and M i n e r a l P r o c e s s E n g i n e e r i n g

We a c c e p t t h i s t h e s i s a s c o n f o r m i n gt o t h e r e q u i r e d s t a n d a r d

THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1988

J a c e k K. R a d l o w s k i , 1988


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In presenting this thesis in partial fulfilment of the requirements for an advanced

degree at the University of British Columbia, I agree that the Library shall make it

freely available for reference and study. I further agree that permission for extensive

copying of this thesis for scholarly purposes may be granted by the head of my

department or by his or her representatives. It is understood that copying or

publication of this thesis for financial gain shall not be allowed without my written

permission.

Department of MlNMJ Cr * W\ KJ\ PfeOCSSS ^MG-KJcS

The University of British Columbia1956 Main MallVancouver, CanadaV6T 1Y3


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A B S T R A C T

The m a t e r i a l t r a n s p o r t s y s t e m i n a n open p i t

mine s i g n i f i c a n t l y a f f e c t s t h e c a p i t a l a n d o p e r a t i n g c o s t s .

A l l t r u c k h a u l a g e i s t h e most common a n d i s a r e l i a b l e and

f l e x i b l e t r a n s p o r t s y s t e m . On t h e o t h e r hand, t h i s s y s t em

i s v e r y e x p e n s i v e and ca n c o s t up t o 50% o f t o t a l m i n i n g

c o s t s . I t s c o s t i s c o n t i n u o u s l y i n c r e a s i n g due t o t h e

i n f l a t i o n o f t h e f u e l , t i r e , a n d l a b o u r e x p e n d i t u r e s .

I n - p i t c r u s h i n g a n d c o n v e y i n g i s a n a l t e r n a t i v e t r a n s p o r t

s y s t e m w h i c h r e g u i r e s a h i g h e r i n i t i a l i n v e s t m e n t b u t g i v e s

s u b s t a n t i a l s a v i n g s i n o p e r a t i n g c o s t s .

An e v a l u a t i o n o f t h e a l l t r u c k s y s t e m v e r s u s

t h e i n - p i t c r u s h i n g a nd c o n v e y i n g s y s t e m h a s been p e r f o r m e d

by means o f a s i m u l a t i o n o f b o th t r a n s p o r t s y s t e m s i n t h e same

mine mode l . R e s u l t s o f t h e s i m u l a t i o n a n d t h e d a t a o b t a i n e d

f r o m t h e f e a s i b i l i t y s t u d i e s p r o v i d e d i n p u t f o r an e conomic

c o m p a r i s o n o f t h e a l t e r n a t i v e t r a n s p o r t s y s t e m s .


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i i i

A cash f low a n a l y s i s showed tha t the i n - p i t

crushing and conveying system was co mp et it iv e wi th the

a l l t r u c k system, g i v i n g a payback w i t hi n fou r yea rs and

r e s u l t i n g i n t o t a l c o s t s over 30% lower than tho se o f an

a l l t r u c k system.

Three computer programs, wr i t te n by the

au thor, have been used to analyse the mine model:

(1) Open P i t S i m u l at i o n Program - t o model a h y p o t h e t i c a l

mine and s imula te i t s haulage o p e r a t i o n over the

mine l i f e ,

(2) Off-Highway Truck S i m u l a t i o n Program - to si mu la te the

t r u c k haulage on average annual rou tes in terms of the

o p e r a t i n g t ime and f u e l consumption f o r t he e s t ima t i on

of the t ruck f l e e t s i z e and the f u e l co s t ,

(3) Cash Flow A n a l y s i s C a l c u l a t i o n Program - t o compare

costs of the a l t e r n a t i v e t r a n s p o r t systems over the

whole pe r iod of a mine l i f e .


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i v

TABLE OF CONTENTS

Page

1. INTRODUCTION , 1

2. LITERATURE REVIEW 3

3. A L L TRUCK TRANSPORT SYSTEM 11

3.1 R e a r Dump O f f - H i g h w a y Tr u c k s 12

3.2 New D e v e l o p m e n t s i n O f f - H i gh w a y T r u c k s 12

3.3 D i r e c t i o n s o f Improvement o f T r u c k E f f i c i e n c y . 14

3.3.1 Improvements i n We i g h t t o Power R a t i o 14

3.3.2 A l t e r n a t i v e F u e l 15

3.3.3 I n c r e a s e i n T r u c k S i z e 16

3.3.4 T r o l l e y Power A s s i s t 17

3.3.5 A u t o m a t i c T r u c k C o n t r o l 2 0

3.3.6 We a t h e r C o n d i t i o n s 21

3.3.7 Ramp G r a d e . . . . ; 214. I N - P I T CRUSHING AND CONVEYING SYSTEM 22

4.1 A d v a n t a g e s o f t h e C o n v e y o r S y s t e m 24

4.2 D i s a d v a n t a g e s o f t h e C o n v e y o r S y s t e m 2 5

4.3. I n f l u e n c e o f Wea the r C o n d i t i o n s 2 6


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TABLE OF CONTENTS

(cont)

Page

8. HIGH ANGLE CONVEYORS 4 7

8.1 Pocket B e l t Conveyor 47

8.2 Sandwich B e l t Conveyor 4 8

9. COMPARISON OF CONVEYORS 51

10. IN-PIT CRUSHING PLANT 56

10.1 Crusher I n s t a l l a t i o n s 56

10.2 Hopper/Feeder Conf igura t ions 61

10.3 A u x i l i a r y Equipment 64

11. HYPOTHETICAL OPEN PIT MINE 66

11.1 General D e s c r i p t i o n : 66

11.2 Ex ca va ti on Procedur e 68

11.3 A l l Truck System 70

11.4 I n - P i t Crushing and Conveying System 72

11.4.1 Conveying across Benches 7711.4.2 Conveying with I n c l i n e 8 0

12. OPEN PIT SIMULATION PROGRAM 8 3

12.1 Model Algor i thm 84

12.2 Pro du ct io n Alg or it hm 89

12.3 Truc k Schedul e Al go ri th m 92


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TABLE OF CONTENTS

(cont)

Page

13. SIMULATION OF THE MINE OPERATION 96

13.1 R e s u l t s and I n t e r p r e t a t i o n 98

13.2 Truck Demands 105

14. EQUIPMENT COST ESTIMATION 114

14.1 A l l Truck System 122

14.2 I n - P i t Crush ing and Convey ing System 124

14.2.1 Conveying across Benches 128

14.2.2 Conveying with I n c l i n e 130

15. CASH FLOW CALCULATION PROGRAM 133

15.1 Main Al go ri th ms 13 3

15.2 Formulae 137

16. DISCOUNTED CASH FLOW ANALYSIS 14 0

17 CONCLUSIONS 162

18. BIBLIOGRAPHY 166


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TABLE OF CONTENTS

(cont)

APPENDIX A Open P i t O p e r a t i o n S i m u l a t i o n Program

Program L i s t i n g and O u t p u t Ta b l e s

APPENDIX B O f f - H i g h w a y T r u c k S i m u l a t i o n Program

Program L i s t i n g and Out put Examples

APPENDIX C Cash Flow C a l c u l a t i o n Program

Program L i s t i n g


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LIST OF TABLES

Page

Table 1 Off-Highw ay Trucks - B a s i c Features 13

Table 2 C a p i t a l Costs of the Conveying System

I s l a n d Copper Mines 3 2

Tab le 3 Sandwich B e l t Conveyor - Te c h n i c a l Data

Majdanpek , Yugos lav ia 5 0

Table 4 I d l e r B e l t Conveyor vs. Cable B e l t Conveyor 52

Table 5 Sandwich B e l t Conveyor

vs . Pocket B e l t Conveyor 54

Table 6 Crusher P l a n t Requirements 57

Table 7 F i x e d Operating Delays 69

Table 8 C h a r a c t e r i s t i c s of Convey ors 76

Table 9 Computer Model - P i t C h a r a c t e r i s t i c s

Input Data Required 88Table 10 Computer Model - Product ion C h a r a c t e r i s t i c s

Input Data Required 94


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X

LIST OF TABLES

(cont)

Page

Table 11 Open P i t S imula t ion Program

Input Parameters 9 6

Tab le 12 Open P i t S imula t ion Program

Reserves Table 99

Table 13 Open P i t S imula t ion Program - A l l Truck System

Ore Truck Haulage Schedule 102

Table 14 Open P i t S imula t ion Program - Con veyi ng System

Ore Truck Haulage Schedule 103

Table 15 Open P i t S imula t ion Program -

Waste Truck Haulage Schedule 104

Table 16 Off-Highway Truc k S imula t ion Program

Input - Truck C h a r a c t e r i s t i c s 107Table 17 Off-Highway Truck S imula t ion Program

A l l Truck System - Ore Truck Demands 108


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L I S T OF TABLES

(cont)

Page

Ta b l e 18 O f f - H i g h w a y Tr u c k S i m u l a t i o n Program

C o n v e y i n g Sys t em - Or e T r u c k Demands 110

Ta b l e 19 O f f - H i g h w a y Tr u c k S i m u l a t i o n Program

Was te T r u c k Demands I l l

Ta b l e 2 0 C o m p a r i s o n o f T r u c k F l e e t R e q u i r e m e n t s

A l l Tr u c k S y s t em v s . C o n v e y i n g S y s t e m 113

Ta b l e 21 E q u i p m en t R e q u i r e m e n t s f o r A l l T r u c k S ys te m 115

Ta b l e 22 E q u i p m en t R e q u i r e m e n t s f o r C o n v e y i n g S y s t e m 116

Ta b l e 23 Cash F low Program - I n p u t R e q u i r e m e n t s .. 134

Ta b l e 24 A l l T r u c k S ys te m - Cash F low A n a l y s i s

T r u c k s , 154 t o n n e c a p a c i t y 141

Ta b l e 25 A l l T r u c k S ys te m - Cash F low A n a l y s i s C r u s h e r ,

S t a t i o n a r y G y r a t o r y 14 2


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L I S T OF TABLES

(cont)

Page

Ta b l e 26 A l l T r u c k Sy st em

C u m u l a t i v e Cash F low A n a l y s i s 14 3

Ta b l e 27 C o n v e y i n g a c r o s s Benches - Cash F low A n a l y s i s

Tr u c k s , 154 t o n n e c a p a c i t y 14 4


C r u sh e r , S t a t i o n a r y G y r a t o r y 145

Ta b l e ' 2 9 C o n v e y i n g a c r o s s Benches - Cash F low A n a l y s i s

C r u s h e r , P o r t a b l e

G y r a t o r y 146

Ta b l e 3 0 C o n v e y i n g a c r o s s Benches - Cash F low A n a l y s i s

M a i n Co n v ey o r , 700 m 14 7


S u r f a c e C o n v e y o r, 2200 m 14 8


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LIST OF TABLES

(cont)

Page

Ta b l e 32 C o n v e y i n g a c r o s s Benche s - Cash F low A n a l y s i s

E x t e n s i o n Co nv ey or , 300 m 149

Ta bl e 3 3 C o n v e y i n g a c r o s s Bench es - Cas h F lo w A n a l y s i s

C u m u l a t i v e Cash F low A n a l y s i s 150

Ta b l e 34 C o n v e y i n g i n I n c l i n e - Cash F low A n a l y s i s

T r u c k s , 154 tonne c a p a c i t y 151

Ta b l e 35 C o n v e y i n g i n I n c l i n e - Cas h F low A n a l y s i s

C r u s h er , S t a t i o n a r y G y r a t o r y 152

Ta b l e 36 C o n v e y i n g i n I n c l i n e - Cash Flow A n a l y s i s

C r u s h e r , P o r t a b l e

G y r a t o r y 153

Ta b l e 3 7 C o n v e y i n g i n I n c l i n e - Cas h Flow A n a l y s i s

M a i n C o n v e y o r , 700 m 154


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LIST OF TABLES

(con t )

Page


S u r f a c e Co nv ey or , 1800 m 155


E x t e n s i o n o f Ma in Co nv ey or , 240 m 156


D r i f t Co nv ey or , 80 m 157


C u m u l a t i v e Cash F low A n a l y s i s 158


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X V

LIST OF FIGURES

Page

F i g . 1 Convent ional Conveyors 53

F i g . 2 High Angle Conveyors 55

F i g . 3 A l l Truck System - S i t e P lan 71

F i g . 4 I n - P i t Crushing & Conveying - S i t e P lan .... 73

F i g . 5 I n - P i t Crushing and Conveying a cro ss Benches

Plan View 78

F i g . 6 I n - P i t Crushing and Conveying a cro ss Benches

Side View 79

F i g . 7 I n - P i t Crushing and Conveying with I n c l i n e

Plan View 81

F i g . 8 I n - P i t Crushing and Conveying with I n c l i n e

Side View 8 2

F i g . 9 Computer Model - P i t Geometry 85

F i g . 10 Computer Model - Mining Sequence 9 3

F i g . 11 Cumulative Costs v s. Time i n Years 161


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ACKNOWLEDGEMENT

I w i s h t o acknowledge P r o f e s s o r A .E . H a l l f o r h i s

v a l u a b l e a d v i c e and t i m e t h a t he c o n t r i b u t e d .

I w i s h a l s o t o acknowledge Dr . H.D.S. M i l l e r who

i n s p i r e d t h i s t h e s i s and P r o f e s s o r s A .L . M u l a r,

G.W. P o l i n g and A . J . R ee d f o r p r o v i d i n g me w i t h

i n f o r m a t i o n I needed.

My s p e c i a l t h a n k s t o my w i f e Z o f i a f o r h e r p a t i e n c e ,

encouragement and s u b s t a n t i a l h e l p i n e d i t i n g t h i s

t h e s i s


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1. INTRODUCTION

The c a p i t a l an d o p e r a t i n g c o s t s o f a n open p i t

mine a r e s i g n i f i c a n t l y i n f l u e n c e d b y t h e c o s t o f m a t e r i a l

h a u l a g e . T he u s u a l means o f m a t e r i a l h a u l a g e a t p r e s e n t i s

o f f - h i g h w a y t r u c k s , a l t h o u g h i t i s o f t e n t h e most e x p e n s i v e

s y s t e m due t o h i gh f u e l c o n s u m p t i o n , wear, a nd l a b o u r c o s t s .

C o s t s o f t h e t r u c k h a u l a g e ca n be as much a s a h a l f o f t he

t o t a l m i n i n g c o s t s , w i t h t h e m a j o r e x p e n d i t u r e s a t t r i b u t e d

t o f u e l , l u b r i c a t i o n , t i r e s and m a i n t e n a n c e .

T h e r e i s a n eed t o examine a l t e r n a t i v e

t r a n s p o r t s y s t e m s . The b e s t s o l u t i o n seems to be c o n v e y o r

t r a n s p o r t , a s i t i s e f f i c i e n t and e c o n o m i c a l i n power

c o n s u m p t i o n . The c o n v e y o r s y s t e m r e s u l t s i n a s i g n i f i c a n t

r e d u c t i o n i n t h e number o f t r u c k s , bu t i t r e q u i r e s t h e r o c k

to be c r u s h e d b e f o r e t r a n s p o r t a t i o n . T h i s i s a c h i e v e d by

t h e p r o v i s i o n o f an i n - p i t c r u s h i n g p l a n t , w h i c h can be more

e x p e n s i v e p e r t o n n e t h a n t h e s t a t i o n a r y o u t o f p i t c r u s h e r

n o r m a l l y u s e d w i t h a l l t r u c k h a u l a g e . The d i f f e r e n c e i n

c r u s h i n g c o s t s i s a t t r i b u t a b l e t o t h e c o s t s o f u s i n g a

c o n v e y o r t r a n s p o r t sy s t em .


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A c o m p a r i s o n o f o p e r a t i n g c o s t s f o r t h e s e

t w o s y s t e m s f a v o u r s t h e c o n v e y o r t r a n s p o r t i n most c a s e s ,

a l t h o u g h t h e mine c o n f i g u r a t i o n i n some c a s e s may make

a c o n v e y o r t r a n s p o r t s y s t e m u n a t t r a c t i v e e c o n o m i c a l l y .

The i n i t i a l i n v e s t m e n t i s l o w e r f o r t h e a l l - t r u c k sys tem,

b e c a u s e o f t h e l o w e r c a p i t a l c o s t o f i t s s t a t i o n a r y c r u s h e r

compared t o t h e m o b i l e one u s e d w i t h c o n v e y o r s . Th e h i g h e r

i n v e s t m e n t w i l l be a m o r t i z e d q u i c k l y however b y s a v i n g s i n

t h e l o w e r o p e r a t i n g e x p e n s e s o f t h e con vey o r sy s t em .

I n a d d i t i o n , t h e c o s t s o f t r u c k t r a n s p o r t i n c r e a s e r a p i d l y

e a c h y e a r , a s a r e s u l t o f i n f l a t i o n o f w o r k i n g c o s t s and

t h e i n c r e a s e d h a u l a g e d i s t a n c e s f r om t h e d ee p er p i t .

The e v a l u a t i o n o f an a l l - t r u c k t r a n s p o r t

s y s t e m v e r s u s a c o n v e y o r t r a n s p o r t s y s t e m i s a v e r y complex

p r o b l e m . To p e r f o r m t h i s t a s k , a d e t a i l e d c o s t a n a l y s i s i s

r e q u i r e d , o v e r t h e whole p e r i o d o f a mine l i f e . T h i s t h e s i s

p r e s e n t s t h e r e s u l t s o f s u c h a c o s t a n a l y s i s a nd compares

t h e r e l a t i v e c o s t s , a d v a n t a g e s an d d i s a d v a n t a g e s o f t h e

two sys tems .


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2. LITERATURE REVIEW

I n t h e p e r i o d 1980 - 1987 many t e c h n i c a l

p u b l i c a t i o n s r a i s e d t h e c o n c e r n s o f t h e h i g h o p e r a t i n g

c o s t s o f t r u c k h a u l a g e i n open p i t m i n e s , o f low m i n e r a l

p r i c e s , and r a p i d e s c a l a t i o n o f f u e l c o s t s .

E f f o r t s t o improve t r u c k e f f i c i e n c y a r e

l o g i c a l l y d i r e c t e d t o improvements i n t h e e n g i n e i t s e l f ,

improvements i n t h e power t o w e i g h t r a t i o and v a r i o u s

schemes a imed a t o p t i m i z i n g t r u c k u t i l i z a t i o n and m i n i m i z i n g

c o s t s . T h i s a c t i v i t y r e s u l t s i n m a r g i n a l improvements an d

n o s e r i o u s b r e a k t h r o u g h ca n be e x p e c t e d (A.K. B u r t o n , 1980) .

I n c r e a s i n g t h e t r u c k s i z e r e s u l t s i n o n l y

a s m a l l r e d u c t i o n o f o p e r a t i n g c o s t s p e r t o n n e a t a much

h i g h e r c a p i t a l c o s t f o r t h e l a r g e r u n i t . F o r exampl e,

t h e c o s t o f a 2 00 t o n n e t r u c k i s o v e r 50% h i g h e r t h a n t h a t

o f a 154 t o n n e model ( L . S . Lyon , 19 80) . L a rg e r t r u c k s a l s o

u s e tandem r e a r a x l e s w h i c h i n c r e a s e t i r e c o s t s .

V e r t i c a l t r u c k h a u l a g e i n e x c e s s o f 150 m

c r e a t e s t r a f f i c and m a i n t e n a n c e p r o b l e m s , t h e s e r e d u c e

e f f i c i e n c y and c o s t s r i s e ( C E . Huss e t a l . , 1983 ) .


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There i s a t r end towards the use of hi gh speed,

l a rg e c a p a c i t y conveyor systems, and these i n s t a l l a t i o n s have

been h i g h l y p r o duc t i ve . C u r r en t l i m i t s o f technology are

a b e l t width maximum of 3.05 m and b e l t speeds o f 6.2 m/s f o r

coarse crushed ma te r i a l (T.W. Mar t in e t a l . , 1981). Higher

speeds are l i m i t e d t o f i n e m a t e r i a l s .

Seve ra l s t ud i e s performed on e x i s t i n g i n p i t

c r u s h i n g i n s t a l l a t i o n s (R.W. U tl e y , 1983) and on h y p o t h e t i c a l

models (T.W. Ma rt in et a l . , 1981) showed co st saving s ranging

from 2 6 to 50%.

Run of mine ma te ri al has t o be crushed to

a conveyable s i z e be fore loa d ing onto a conveyor.

Crushing has to be done i n t he p i t . There a re i n p i t

c r u s h e r c o n f i g u r a t i o n s , such as mobile, semi-mobile,

movable, modular, semi -f ix ed, and f i x e d (E.M. F r i z z e l l ,

1983) . Design of mobi le c rus hers has advanced to the point

where they are as rugged and r e l i a b l e a s s t a t i ona rycrushers . In Europe, owners who have operated both mobile

and s ta t i on ar y c rushers p re fe r the mobi le un i t s a s they are

more economical (H.G. Kok, 1982).

Crusher e l ev a t io n should be conv enie n t ly

c lose to the cen t ro id o f the mate r ia l s be ing mined.

Pr ef er ab ly , the i n p i t crush er should be loc at ed on a s i t e


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t h a t w i l l not r e q u i r e mi ning f o r one or more years to avoid

f requent r e l o c a t i o n s . I n - p i t cru she r throughput i s up t o 2 0%

h igher than the throughput achie ved through the same c ru sher

l o c a t e d at the p i t r im and s u p p l i e d by haul t r u c k s ( C E . Huss

e t a l . , 1983). T h i s r e s u l t s from b e t t e r u t i l i z a t i o n of the

c rushe r by t r u c k s operat ing only w i t h i n the p i t and cont ino us

feed to the cr us he r by apron feeder.

Conventional l a r g e - c a p a c i t y conveyors are

widely used around th e wo rl d. One o f the l a r g e s t opera t ions

i s a t For tuna, West Germany, where over 14,000 tonnes of

l i g n i t e per hour are handled by conveyor b e l t s .

In North America, t he re a re s ix s i g n i f i c a n t

rock moving opera t ions which use conveyors f o r haulag e

i n open p i t mines. At the Twin Butt es i n Ar izona where

conveyors have been used s i n c e 1965. At the S e r r i t a open

p i t copper mine, a l s o i n Ar izona, conveyors moved over

58 m i l l i o n t onnes of or e and waste i n 1979 (T.M. Brady et

a l . , 1982). The Bingham Canyon Copper Mine produces 70,000

tonnes of ore a day us ing a semi-mobile 1.5x2.7m (60-109 in.)

gyra to ry cr us he r and s i x conveyor f l i g h t s of a t o t a l length

of abo ut 8.5 km. The c a p a c i t y of t h i s system i s 9,000 tonnes


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p e r h o u r (D. K a e r s t , 1987) . I n Canada s o f a r t h r e e open p i t

mines u s e i n - p i t c r u s h i n g a nd c o n v e y i n g s y s t e m . T h e s e a r e

G i b r a l t a r M i n e s , I s l a n d C o p p e r M i n e s , a n d H i g h l a n d Va l l e y

C op pe r, a l l l o c a t e d i n B r i t i s h Columbia .

B a s i c c o n v e y o r d e s i g n p r o c e d u r e i s g i v e n i n

t h e CEMA book (1979 ) . Fo r a b e l t c a r r y i n g c o a r s e c r u s h e d

m a t e r i a l i t i s d e s i r a b l e t o keep t h e c r o s s s e c t i o n a l l o a d

t o l e s s t ha n 80% of t he CEMA s t a n d a r d s , when c a r r y i n g the

d e s i g n e d t o n n a g e t o a v o i d s p i l l a g e . F o r c o a r s e o r e

c o n v e y o r s , t h e recommended sp ee d i s 4 t o 5 m/s whereas f o r

ov er bu rd en c on ve yo rs i t i s 5 t o 8 m/s (A.D. F e r n i e , 1985).

The a l t e r n a t i v e C a b l e B e l t co nve yo r has

a maximum c a p a c i t y o f 4,600 ton nes pe r hour, wh ich l i m i t s

i t s a p p l i c a t i o n t o medium s i z e open p i t m i n e s . T h i s type

o f c o n v e y o r h a s f o u n d a p p l i c a t i o n i n s e v e r a l h a r d r o c k

o p e r a t i o n s a r o u n d t h e w o r l d , m o s t l y as o v e r l a n d i n s t a l l a t i o n s

(D.E. Brown, 1983 & 198 6) .

C o n v e n t i o n a l b e l t c o n v e y o r s c a n t r a n s p o r t m a t e r i a l s

a t a n g l e s a p p r o a c h i n g 1 8 . H i g h a n g l e b e l t c o n v e y o r s ,

l i k e th e sandwic h co nve yor and po ck e t con vey or, can t r a n s p o r t

m a t e r i a l a t h i g h a n g l e s u p t o 9 0 , w h i l e m a i n t a i n i n g

t h e most p o s i t i v e f e a t u r e s o f c o n v e n t i o n a l c o n v e y o r s


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- 7 -

( J .A . do s S a nt os & E.M. F r i z z e l l , 1983) . Sandwich

b e l t c o n v e y o r s o f f e r : h i g h c a p a c i t y up to 9,000 t o n n e s / h ,

l i f t s t o 300 m, and a ng l es i n ex ce ss o f 45 . The co nv ey or

can be i n s t a l l e d a c r o s s t h e b e n c h e s w i t h r e l a t i v e l y s m a l l

p r e p a r a t i o n . I t c a n a l s o be e a s i l y r e l o c a t e d t o a n o t h e r

a r e a o f t h e mine. The a p p l i c a t i o n o f th e sandw ich b e l t

c o n v e y o r does n o t r e q u i r e a change i n mine p l a n n i n g

( J .A . Dos San to s , 1983) whi ch i s an im po rt an t c o n s i d e r a t i o n .

A n o t h e r h i g h a n g l e c o n v e y i n g method i s

t h e F l e x o w a l l p o c k e t c o n v e yo r. T h i s typ e o f con vey or can

be o f v a r i o u s c o n f i g u r a t i o n s : s t r a i g h t , i n c l i n e d , "L", "S",

and 1 1 C" sha pe s (J.W. P a e l k e , 1982) . B a s i c f e a t u r e s o f

t h e F l e x o w a l l c o n v e y o r a n d c u r r e n t i n s t a l l a t i o n s have

been d e s c r i b e d by U. Kunstmann & J.W. P a e l k e (19 84) , an d

J.W. P a e l k e e t a l . , ( 1 9 8 6) . C a p a c i t y o f t h e p o c k e t b e l t

c o n v e y o r i s l i m i t e d by the lump s i z e o f th e conv eyed

m a t e r i a l . The maximum o p e r a t i n g a n g l e , t h e r e f o r e , i s

d e t e r m i n e d b y a m a t e r i a l s i z e and t h i s must a lw ays be

c o n s i d e r e d i n t h e d e s i g n o f s u c h i n s t a l l a t i o n s .

S e l e c t i o n o f t h e most e c o n o m i c a l o p e r a t i o n

r e q u i r e s e v a l u a t i o n o f s e v e r a l m i n i n g schemes s i n c e a l l

open p i t mines a r e d i f f e r e n t , a nd p l a n n i n g a m u l t i - s y s t e m

method of ore and was te e x t r a c t i o n i s g e n e r a l l y more


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complex than fo ll ow in g the t r a d i t i o n a l shove l / t ruck method

with i t s f l e x i b i l i t y . An ope rat ing mine, that is planning

to use i n - p i t crushing and conveying as a replacement for

the shovel / t ruck system, must deve lop c once pts t h a t can be

worked i n t o the e x i s t i n g p i t wi thout i n t e r f e r i n g wi th d a i l y

produc t ion .

Such pla nnin g may re qu ir e deve lopi ng se ve ra l

d i f f e r e n t schemes to f i n d the most p r a c t i c a l and cost

e f f e c t i v e method of t r an sp or t i ng the ore from p i t to p lan t .

For example:

I t may be de si r ab le to s t r i p overburden to the f i n a l

p i t perimeter before i n s t a l l i n g the a l t e r n a t i v e

system. Pushing back p i t wa l l s r equ i res r e l o c a t i o n

of the main conveying system and would be very

d i f f i c u l t during the p i t oper at io n.

When s e l e c t i v e mining i s r equ i red , mul t ip le working

fa ces may be needed, usi ng smal ler loa di ng and haul

equipment.

Operating layout can change with inc reas ed i n - p i t

h o r i z o n t a l haulage.


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T he c r u s h i n g p l a n t b e n c h a r e a must be a d e q u a t e f o r

t h e c r u s h i n g p l a n t , a u x i l i a r i e s , t r a n s p o r t an d

s e r v i c e e q u i p m e n t , t r u c k dump h o p p e r and c r u s h e r

f e e d e r , d i s c h a r g e c o n v e y o r and ma in c o n v e y o r t a i l

s e c t i o n .

The dumping a r e a o f t h e c r u s h e r must h a v e a d e q u a t e

s p a c e f o r t r u c k manoeuvers.

When t h e c r u s h e r o r c o n v e y o r a r e t e m p o r a r i l y down,

t h e r e must be a d e q u a t e s p a c e t o a c c u m u l a t e a s u rg e

p i l e . P r e f e r a b l y t r u c k s s h o u ld be s w i t c h e d t o wast e

h a u l a g e t o p r e v e n t r e h a n d l e .

The s t a b i l i t y o f t h e dumping b e n c h may r e q u i r e

a s p e c i a l r e i n f o r c e m e n t o r e l s e a dumping h o p p e r

may b e n e c e s s a r y.

Ad equ a t e d i s t a n c e s h o u l d be p r o v i d e d t o p r e v e n t

f l y r o c k damaging t h e i n - p i t c r u s h i n g p l a n t an d

c o n v e y o r s d u r i n g b l a s t i n g . I n h a r d r o c k m i n i n g

t h i s d i s t a n c e u s u a l l y v a r i e s f r om 150 t o 300 m,

a l t h o u g h 120 m i s c o n s i d e r e d s a f e .


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The o p e r a t i o n a l l a y o u t must p r o v i d e f o r moving

t h e c r u s h e r p l a n t , r e l a t e d equ ipment a nd e x t e n d i n g

t h e c o n v e y o r, t h u s t h e l a y o u t must p r o v i d e ramps

o f 7 t o 10% gra de, h au l ro ad s ap pr ox im at el y 30 m

w i d e , and the new s i t e f o r r e l o c a t i o n on a d e e p e r

b e n c h must be p re pa re d .

For a b e l t c o n v e y i n g s y s t e m a more d e t a i l e d d e s i g n

i s r e q u i r e d t h a n f o r c o n v e n t i o n a l t r u c k h a u l a g e .

I t i s t h e o r e t i c a l l y p o s s i b l e t o u se j u s t one b e l t

o r add a d d i t i o n a l s ec t ions (R .M. Hays , 1983)

T h e c r u s h e r s i t e s must b e p r e - p l a n n e d t o m i n i m i z e

t h e l o c k - u p o f t o n n a g e b y t h e c r u s h e r . T h i s a f f e c t s

t h e c r u s h e r moving s c h e d u l e a n d r e l o c a t i o n c o s t s .

C o n v e y o r t r a n s p o r t s y s t e m s r e d u c e t h e t r u c k

m a i n t e n a n c e p e r s o n n e l a nd i n f r a s t r u c t u r e

s i g n i f i c a n t l y .


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3 . ALL TRUCK TRANSPORT SYSTEM

The a l l t r u c k t r a n s p o r t s y s t e m i s t h e mos t

common t r a n s p o r t a t i o n method and i s w e l l e s t a b l i s h e d i n

open p i t m i n i n g . I t p r o v i d e s h i g h r e l i a b i l i t y , e x c e l l e n t

f l e x i b i l i t y and f u l l y s a t i s f i e s needs f o r m a t e r i a l s

b l e n d i n g . I t s d i s a d v a n t a g e i s t h a t i t i s a l s o v e r y

e x p e n s i v e i n t e r m s o f o p e r a t i n g c o s t s and t r u c k s e r v i c e

f a c i l i t i e s . I n remote a r ea s d r i v e r s a nd m e c h a n i c s may

r e q u i r e h o u s i n g and t r a n s p o r t .

I n t h e a l l t r u c k s y s t e m , t h e m a t e r i a l i s

e n t i r e l y h a u l e d out o f th e p i t t o t h e s u r f a c e f a c i l i t i e s .

W i t h i n c r e a s e d p i t d e p t h , l o n g u p h i l l h a u l s c a u s e e x c e s s i v e

m a i n t e n a n c e p r o b l e m s and d e c r e a s e t r u c k a v a i l a b i l i t y .

I n t h i s c h a p t e r t h e t r u c k h a u l a g e s y s t e m i s

b r i e f l y d e s c r i b e d , and th e d i r e c t i o n o f p o s s i b l e improvements

i s d i s c u s s e d f u r t h e r .


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3 .1 R e a r Dump O f f - H i g h w a y Tr u c k s

T h e r e a r dump t r u c k i s t h e most p o p u l a r t y p e

o f r u b b e r - t i r e d h a u l a g e v e h i c l e u s e d i n open p i t s and ca n

h a u l a l m o s t any t y p e o f m a t e r i a l . I t s body i s mounted ont h e t r u c k c h a s s i s and ca n be r a i s e d b y a h y d r a u l i c h o i s t

sy s t em.

The dump t r u c k i s e q u i p p e d w i t h an e l e c t r i c

whee l o r m e c h a n i c a l d r i v e , and ca n be d r i v e n by two a x l e s

o r r e a r a x l e o n l y . B a s i c f e a t u r e s o f t h i s t y p e o f t r u c k

a r e g i v e n i n Ta b l e 1.

3.2 New Deve lopments i n O f f - H i g h w a y Tr u c k s

I n t h e p a s t 25 y e a r s many c h a n g e s have been

made t o h a u l a g e t r u c k s and t h e y have had s i g n i f i c a n t impac t

i n t h e m i n i n g i n d u s t r y . I n th e 1960's p a y lo a d c a p a c i t i e s

i n c r e a s e d f r o m 60 t o 90 t o n n e s . The most i m p o r t a n t

t e c h n o l o g i c a l a c h i e v e m e n t was the e l e c t r i c d r i v e s y s t em

i n t r o d u c e d by G e n e r a l E l e c t r i c and U n i t R i g Equipme nt

Company. The b i g g e s t improvement i n t h e 1970's was t h e

d e v e l o p m e n t o f a 154- tonne d i e s e l e l e c t r i c t r u c k .


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TABLE 1

OFF-HIGHWAY TRUCKS - BASIC FEATURES

C a p a c i t y 45 t o 320 t onnes

Pow er 300 t o 2,250 kW

V e h i c l e w e i g h t 26,000 t o 236,000 k g

D r i v e M e c h a n i c a l d r i v e sys tem,up t o 118 t o n n e s c a p a c i t y

E l e c t r i c a l wheel sys tem,77 t o 180 t onnes

E l e c t r i c a l a x l e d r i v e sys tem,210 t o 320 t onnes

Top speed 48 t o 72 km/h

A v e r a g e a v a i l a b i l i t y 75%

Payload/EVW a p p r o x . 1.5

P o w e r / P a y l o a d a p p r o x . 8.2 kW h/t onn e


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Over 1400 o f t h e s e u n i t s have been b u i l t and t h e y a r e

i n o p e r a t i o n i n e v e r y a r e a o f t h e w o r l d . T h i s t r u c k i s

c o n s i d e r e d t o be t h e most p r o d u c t i v e , e f f i c i e n t and

e c o n o m i c a l , and i t s r e l i a b i l i t y and e a s e o f m a i n t e n a n c e

have been p r o v e n o v e r many y e a r s .

3.3 D i r e c t i o n s o f Improvement o f T r u c k E f f i c i e n c y

E f f o r t s t o improve t r u c k e f f i c i e n c y a r e

d i r e c t e d t o i m p r o v i n g t h e w e i g h t t o power r a t i o , t h e

e n g i n e i t s e l f , and v a r i o u s schemes a imed a t o p t i m i z i n g

t r u c k u t i l i z a t i o n and m i n i m i z i n g c o s t s .

3.3.1 Improvements i n Weigh t t o Power R a t i o

The w e i g h t t o power r a t i o i s b e i n g improved

by b o o s t i n g t h e power o f e x i s t i n g e n g i n e s . T h e r e a r e

p o t e n t i a l a p p l i c a t i o n s o f t w i n h i g h s p e e d d i e s e l s i n h i g h e r

power r a n g e s , t o compete w i t h t h e h e a v i e r l ow-speed

l o c o m o t i v e t y p e d i e s e l e n gi n es , c u r r e n t l y i n u s e . F u r t h e r

improvements a r e a l s o b e i n g made i n t u r b o c h a r g in g and h i g h

p r e s s u r e f u e l i n j e c t i o n .


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3.3.2 A l t e r n a t i v e F u e l

T h e c o n v e r s i o n o f d i e s e l e n g i n e s t o a n a t u r a l

g a s / d i e s e l d u a l f u e l mode i s an a t t e m p t t o r e d u c e t r u c k

o p e r a t i n g c o s t s . I t i s e x p e c t e d , t h a t d u a l - f u e l o p e r a t i o n

w o u l d r e p l a c e up t o 80% o f d i e s e l f u e l c o n s u m p t i o n w i t h

n a t u r a l g a s w h i c h c o s t s h a l f as much as t h e d i e s e l .

N a t u r a l g a s w o u l d n o r m a l l y o n l y be u s e d f o r h a u l a g e up

t h e ramp t o m i n i m i z e c o n v e r s i o n p r o b l e m s o f low l o a d

o p e r a t i o n s .

To make the n a t u r a l ga s o p e r a t i o n f e a s i b l e ,

t h e f o l l o w i n g p r o b l e m s n e e d t o be s o l v e d :

A c o n v e r s i o n k i t needs t o be d e v e l o p e d t o o p e r a t e

t h e e n g i n e i n n a t u r a l g a s / d i e s e l d u a l f u e l mode

- S t o r a g e o f n a t u r a l ga s on b o a r d t h e t r u c k .


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3.3.3 In c r ea se i n T r u c k S i z e

Man y m i n i n g companies a r e l o o k i n g f o r l a r g e r

t r u c k s t o r e d u c e t h e i r h a u l a g e c o s t s . An i n c r e a s e i n t h e

t r u c k s i z e l o w e r s t h e o p e r a t i n g c o s t p e r t o n n e , b e c a u s e :

T r u c k d r i v e r c o s t pe r t o n n e d e c r e a s e s ,

- R e p a i r c o s t s g r a d u a l l y d e c r e a s e , w i t h a f a i r l y l a r g e

d r o p between a 68- tonne t r u c k a nd a 109- tonne t r u c k ,

T i r e , f u e l and l u b r i c a t i o n c o s t s d e c r e a s e p e r t onne

h a u l e d .

The i n t r o d u c t i o n o f h e a v y t r u c k s e x c e e d i n g

180 t o n n e c a p a c i t y s i g n i f i c a n t l y i n c r e a s e s c a p i t a l c o s t s ,

b e c a u s e o f t h e p r o v i s i o n o f t w i n a x l e s y s t e m s .

T h e i n c r e a s e d t i r e wear a l s o e x p e r i e n c e d w i t h t h e s e models

h a s l i m i t e d t h e i r use by mine o p e r a t o r s .


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3.3.4 T r o l l e y Power A s s i s t

The t r o l l e y a s s i s t s y s t e m c o n s i s t s of an

o v e r h e a d power l i n e , c u r r e n t c o l l e c t o r ( p a n t o g r a p h ) mounted

on the t r u c k , and add-on c o n t r o l equ ipme nt . The e x t e r n a l

e l e c t r i c power i s r o u t e d t h r o u g h t h e c o n t r o l equ ipment t o

t h e m o t o r i z e d w h e e l s . T he d i e s e l e n g i n e i s u s e d t o p r o p e l

t h e t r u c k on l e v e l s e c t i o n s o f the road . On i n c l i n e s , the

whee l moto rs o f th e t r u c k a r e c o u p l e d b y t h e c u r r e n t

c o l l e c t o r t o t h e o v e r h e a d power l i n e .

The c o n v e n t i o n a l d i e s e l e l e c t r i c t r u c k i s

e q u i p p e d w i t h t wo d . c . m o t o r s mounted on the r e a r a x l e .

They d r i v e t h e r e a r w h e e l s t h r o u g h p l a n e t a r y g e a r b o x e s .

N o r m a l l y t h e d i e s e l eng ine and an a l t e r n a t o r i s u s e d t o

power t h e whee l mot ors . The d i e s e l e n g i n e h a s l o w e r o u t p u t

t h a n t h e whee l m o t o r s w h i c h l i m i t s t h e t r u c k p e r f o r m a n c e .

When t h e t r o l l e y power a s s i s t i s a p p l i e d , t h e t r u c k

p e r f o r m a n c e i s s i g n i f i c a n t l y enhanced : t r u c k speed can

be i n c r e a s e d b y a p p r o x i m a t e l y 4 5% , a nd f u e l c o n s u m p t i o n

re du ce d by 75%.

I n t h e 1960's, t h e t r o l l e y power a s s i s t

was u t i l i z e d by Quebec C a r t i e r M i n i n g C o . u n t i l t h e mine


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- 18 -

was c l o s e d . P r e s e n t l y , t h i s s y s t e m i s u s e d i n t h r e e Sou th

A f r i c a n m i n e s , P h a l a b o r w a Mi n i ng Co. , ISCOR S i sh en and

R o s s i n g Uran ium. T he S i s h e n i r o n o r e mine, of 60 m i l l i o n

t o n n e s a n n u a l p r o d u c t i o n , c l a i m s s a v i n g s on d i e s e l f u e l o f

20%, i n c r e a s e i n d i e s e l e n g i n e l i f e by 45%, and e x t en s io n

o f wheel motor l i f e by 88%. The t r u c k s p e e d on 8% g r ade

was i n c r e a s e d by 4 6% when u s i n g t r o l l e y a s s i s t . Siemens

a r e c u r r e n t l y e x t e n d i n g t h e R o s s i n g s y s t e m a t a cos t

o f $750,000 by i n s t a l l i n g a 3 MW r e c t i f i e r t o c o n v e r t t h e

11 kV a. c. s u p p l y t o 1200 V d. c. and i n s t a l l i n g a f u r t h e r

1 km o v e r h e a d e l e c t r i c l i n e s y s t e m c o m p r i s i n g d o u b l e c o n t a c t

w i r e s u p p o r t e d by f r e e s t a n d i n g s t e e l m a s t / c a n t i l e v e r

s t r u c t u r e s . A r e d u c t i o n o f f u e l c o n s u m p t i o n f r o m 24 1/km

t o l e s s tha n 4 1/km i s c l a i me d when t h e t r u c k s o p e r a t e o n

a 1200 V d. c. s u p p l y on a g r a d i e n t o f 8% and 1050 V d. c.

f o r 10% gra de. Speeds a r e a l m o s t d o u b l e d r e s u l t i n g i n b e t t e r

f l e e t u t i l i z a t i o n and i n c r e a s e d p r o d u c t i v i t y

(S .A. Min ing Wo r l d , Nov. 1987).

The t r o l l e y a s s i s t i s a v e r y p r o m i s i n g a p p r o a c h

t o l o w e r mine o p e r a t i n g c o s t s , and i n c r e a s e p r o d u c t i v i t y .

U n f o r t u n a t e l y , t h e c a p i t a l c o s t o f t h i s s y s t e m i s v e r y h i g h ,

and i t s a p p l i c a t i o n i s o n l y p r o f i t a b l e where f u e l i s v e r y

e x p e n s i v e compared t o e l e c t r i c e n e r g y. M o r e o v e r, i t r e d u c e s

t h e f l e x i b i l i t y o f t h e t r u c k f l e e t and imposes t r a f f i c


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p r o b l e m s and l i m i t a t i o n s . Th e c l e a r a n c e between t h e t r u c k

and the t r o l l e y w i r e i s c r i t i c a l and t he p a n t o g r a p h can

u s u a l l y o n l y c a t e r f o r 0.3 m change. The p a n t o g r a p h t h e n

l o s e s c o n t a c t a nd t h e t r u c k l o s e s power. T h i s s l o w s t he

t r u c k a nd d e l a y s a l l o t h e r t r u c k s b e h i n d i t on t h e h a u l

r o a d . T h e h e a v y r a i n f a l l and f r o s t heave e x p e r i e n c e d i n

W e s t e r n C a n a d i a n M i n e s make t h e c o n t r o l o f c l e a r a n c e t o

t h i s t o l e r a n c e i m p o s s i b l e u n l e s s t h e h a u l r o a d i s paved .

T h e s e f a c t o r s have r e s u l t e d i n t h e t r o l l e y a s s i s t s y s t e m no t

b e i n g a d o p t e d by any We s t e r n C a n a d i a n open p i t o p e r a t i o n s .


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- 20 -

3.3.5 Au to ma t i c Tr u c k C o n t r o l

T h e c o n c e p t o f A u t o m a t i c T r u c k C o n t r o l (ATC)

i s t h e r emo te c o n t r o l a nd d i s p a t c h o f t h e t r u c k . A d r i v e r ' s

a s s i s t a n c e i s o n l y neede d t o e n t e r o r e x i t t h e s y s t e m .

The b a s i c s y s t e m c o n s i s t s o f t h e o n - b o a r d

c o n t r o l e q u i p m e n t a n d t h e w a y s i d e c o n t r o l equ ipmen t .

Th e wa ys ide equ ipmen t c o n s i s t s o f a b u r i e d g u i d e w i r e ,

b l o c k c o n t r o l u n i t s , an d a c e n t r a l c o n t r o l l e r w h i c h p r o v i d e s

p r e d e t e r m i n e d s i g n a l s t o t h e o n - b o a r d e q u i p m e n t f o r spee d

c o n t r o l , s t e e r i n g , a nd f o r a u x i l i a r y f u n c t i o n s t h r o u g h t h e

g u i d e w i r e l o c a t e d i n t h e t r u c k p a t h .

T h e A u t o m a t i c Tr u c k C o n t r o l s y s t e m i s s t i l l

u n d e r d e v e l o p m e n t , b u t a n e c o n o m i c a n a l y s i s showed t h a t

t h e u s e o f ATC c o u l d r e d u c e d r i v e r s ' l a bo u r by 50% .

A d d i t i o n a l l y , t h e s h o v e l u t i l i z a t i o n wou ld improve a s t h e

s h o v e l w o u l d c o n t i n u e t o work a t s h i f t c h a n g e s , l u n c h t i m e

an d o t h e r b r e a k s p r e s e n t l y r e q u i r e d by d r i v e r s .

The a p p l i c a t i o n o f ATC may a l s o r e s u l t i n a s a f e r m i n i n g

o p e r a t i o n , b y r e d u c i n g human e r r o r s an d human e x p o s u r e

t o l a r g e e qu ip men t .


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- .21 -

3 . 3 . 6 Weather C o n d i t i o n s

T r u c k o p e r a t i o n s a r e a d v e r s e l y a f f e c t e d by

wet c o n d i t i o n s , low t e m p e r a t u r e s and p a r t i c u l a r l y by fo gs .

A l l t h e s e c o n d i t i o n s o c c u r i n We s t e r n C a n a d i a n open p i t

o p e r a t i o n s .

3 . 3 . 7 . Ramp Grade

W h i l s t g r a d e s o f 10 t o 12% a r e more e c o n o m i c

f o r t r u c k o p e r a t i o n i n s h a l l o w p i t s , o v e r h e a t i n g o f wheel

m ot o r s o n l o n g ramps o f t h i s g r a d e l i m i t s deep p i t o p e r a t o r s

t o u s i n g 8 % maximum g r a d e s .


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4. IN-PIT CRUSHING AND CONVEYING SYSTEM

I n - p i t c r u s h i n g and c o n v e y i n g i s a n a l t e r n a t i v e

s y s t e m f o r t r a n s p o r t i n open p i t m i n e s . The b i g g e s t

a d v a n t a g e o f t h i s s y s t e m i s a s i g n i f i c a n t r e d u c t i o n o f t he

t r u c k h a u l a g e by i n t r o d u c i n g t h e i n - p i t c o n v e y o r . I f a mine

p r o v i d e s two c o n v e y o r s , b o t h o r e and was te a r e c o n v e y e d ou t

o f t h e p i t . T h i s way, the t r u c k t r a n s p o r t on l o n g u p h i l l

d i s t a n c e s i s e l i m i n a t e d . When t h e mine s u p p l i e s o n l y one

c o n v e y o r , i t c o n v e y s o r e and was te on d i f f e r e n t s h i f t s , o r

a l l t h e w a s t e i s t r a n s p o r t e d by t r u c k s t o t h e s u r f a c e .

The i n - p i t c r u s h e r i s moved down e v e r y one

o r two y e a r s , t o keep t h e t r u c k h a u l a g e t o a minimum.

The r e l o c a t i o n t a k e s 2-3 d a y s . F o r s h o r t moving t i m e s t h e

p r o c e s s i n g p l a n t c a n b e f e d f r om a s t o c k p i l e . I n l o n g e r

s t o p p a g e s , u s u a l l y i n E u r o p e a n o p e r a t i o n s , t h e move c o i n c i d e s

w i t h a g e n e r a l mine h o l i d a y p e r i o d .

T h e c r u s h e r i s l o c a t e d n e x t t o an embankment,

s o t h a t t r u c k s a r e a b l e t o dump t h e m a t e r i a l d i r e c t l y f rom

t h e embankment i n t o t h e h o p p e r / f e e d e r above t h e c r u s h e r .

Under an a l t e r n a t i v e a r r a n g e m e n t , t h e c r u s h e r i s l o c a t e d

c l o s e r t o t h e p i t c e n t r e and ha s a s e p a r a t e f e e d e r w i t h


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t h e f e e d e r t a i l - e n d l o c a t e d i n t h e r e c e s s i n t h e p i t f l o o r .

T h e t r u c k s dump t h e m a t e r i a l f ro m t h e p i t f l o o r i n t o t he

h o p p e r on t h e f e e d e r .

B e l t co nv ey or s ca n be one of th e most

e f f i c i e n t means o f t r a n s p o r t i n g m a t e r i a l o u t o f t h e p i t .

They have been s u c c e s s f u l l y p r o v e n i n c o a l m i n i n g , b u t

t h e y a r e n o t s o p o p u l a r i n m e t a l m i n i n g .

T h e r e a r e t h r e e t y p e s o f b e l t c o n v e y o r s

t h a t ca n be use d i n ha rd roc k mi n i ng : i d l e r s u p p o r t e d

c o n v e y o r, c a b l e s u p p o r t e d c o n v e y o r an d h i g h a n g l e c o n v e y o r.

T h e s e a r e d e s c r i b e d i n d e t a i l i n c h a p t e r s 5, 6 and 7.


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4.1 A d v a n t a g e s o f t he Conveyor Sys t em

The i n - p i t t r a n s p o r t s y s t e m i s more

e c o n o m i c a l t h a n a l l t r u c k t r a n s p o r t , a nd c an s i g n i f i c a n t l y

l o w e r m i n i n g c o s t s . The f o l l o w i n g a s p e c t s o f t he sy s t em

c o n t r i b u t e t o t h e s a v i n g s :

R e d u c t i o n o f t h e t r u c k f l e e t , and c o n s e q u e n t r e d u c t i o n

o f t h e d r i v i n g a nd m a i n t e n a n c e p e r s o n n e l , m a i n t e n a n c e

f a c i l i t i e s and f u e l s t o r a g e ,

- R e d u c t i o n o f t h e t r a n s p o r t d i s t a n c e f rom t h e p i t s i n c e

c o n v e y o r s c a n o p e r a t e s a f e l y u p t o a 2 5% g r a d e c a r r y i n g

lumps o f 2 50 mm i n s i z e v e r s u s 12% maximum e c o n o m i c

g r a d e f o r t r u c k s ,

T h r o u g h p u t c a p a c i t y o f t h e i n - p i t m o b i l e c r u s h e r i s

a p p r o x i m a t e l y 2 0% h i g h e r t h a n t h a t o f a s t a t i o n a r y

c r u s h e r , b e c a u s e o f i m p r o v e d u t i l i z a t i o n ,

L e s s f u e l and l u b r i c a n t c o n s u m p t i o n , l e s s t i r e wear,

C o s t o f e l e c t r i c e n e r g y i s more s t a b l e t h a n t h a t o f

d i e s e l f u e l ,

Dependence on w o r l d a v a i l a b i l i t y o f f u e l i s g r e a t l y

r e d u c e d .


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4.2 Di sa dv an ta ge s o f th e Convey or Sys tem

The i n - p i t c o n v e y o r s y s t e m a l s o h a s some

d r a w b ac k s . T h e s e d i s a d v a n t a g e s a r e a s f o l l o w s :

The i n i t i a l c o s t o f t h e s y s t e m i s n o r m a l l y h i g h e r

t h a n t h a t o f t h e t r u c k h a u l a g e s y s t e m , b e c a u s e t h e

c o m p l e t e c o n v e y o r a nd c r u s h e r a r e b o u g h t t o s t a r t

p r o d u c t i o n whereas t h e t r u c k f l e e t ca n be bou ght

i n s t a g e s t o s t e p up p r o d u c t i o n ,

T h e m i n i n g o p e r a t i o n i s c o m p l e t e l y d e p e n d en t o n

a v a i l a b i l i t y o f t h e c o n v e y o r s ; t h i s a v a i l a b i l i t y

i s over 95% but a shutdown of one b e l t c a n s t o p t h e

e n t i r e p r o d u c t i o n ,

R e l o c a t i o n o f t h e c r u s h e r a nd e x t e n s i o n o f t h e

c o n v e y o r i s e x p e n s i v e an d r e q u i r e s a shutdown o f

t h e m i n i n g o p e r a t i o n f o r a p e r i o d fro m 2-3 da ys ,

M a t e r i a l must b e c r u s h e d t o a s i z e o f minus 2 50 mm

b e f o r e l o a d i n g o n t o t h e c o n v e y o r.


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4.3 Inf lue nce of Weather Cond i t ions

In low temperatures of l e s s th an -4 5C,

some o p e r a t i o n a l problems a re cre ate d:

The conveyor system must operate without i n t e r r u p t i o n ;

otherwise , b e l t s f r e e z e t o p u l l e y s and i d l e r s , which

leads t o b e l t damage dur i ng the r e - s t a r t ,

Maintenance has to be reduced t o a minimum.

Repair welding i s har dly p o s s i b l e and c l e a n i n g work

i s imposs ib le un less automated,

The power r a t i n g in cr ea se s with decrease of temperature.

Gear r educers have to be heated by heater rods i n s i d e

gear housings, or heating p l a t e s at the bottom of the

gears of conveyors,

B e l t c r y s t a l i z a t i o n occurs at -55C.


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5. CASE STUDIES - IN-PIT CRUSHING AND CONVEYING SYSTEM

5.1 Twin B u t t e s

T h i s open p i t o p e r a t i o n i n Pima County,

A r i z o n a u s e s a n o v e r b u r d e n h a n d l i n g s y s t em, c o n s i s t i n g o f

t h r e e 1.5 m w ide b e l t c o n v e y o r s , w i t h a c a p a c i t y o f 7,2 00

t o n n e s / h e a c h . T he mine a l s o employs a few k i l o m e t r e s o f

c o n v e y o r s t o move c rushed ore f rom two i n - p i t c r u s h e r s t o

s t o c k p i l e s on the s u r f a c e (C.R. S t J o h n & J.W. Kr on ke , 19 75 ).

5.2 Duval C o r p o r a t i o n - S i e r r i t a Coppe r Mine

T h i s l a r g e open p i t i n S a h u a r i t a , A r i z o n a ,

U.S.A. p r o d u c e s 83,000 t o n n e s d a i l y o f co pp er o r e and

150,000 t o n n e s o f w a s t e . D u r i n g 1982-83, t h e mine d e v e l o p e d

an e x i s t i n g h au l age sy s t em ba s e d on s t a t i o n a r y i n - p i t o r e

c r u s h i n g a n d c o n v e y i n g i n t o movable i n - p i t c r u s h i n g w i t h

e x t e n d a b l e co n ve yi ng f o r o r e and was te . The new sys tem

c o n s i s t s o f t h r e e movable 1.5x2.2 m (60-89 in . ) g y r a t o r y


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c r u s h e r s , t r a n s p o r t e r u n i t , movable s t a c k e r , and 7.3 km o f

c o n v e y o r s w i t h i n s t a l l e d power o f 14,000 kW. The t o t a l

c a p i t a l i n v e s t m e n t was e s t i ma te d a t 32 m i l l i o n U.S. d o l l a r s .

A v e r a g e c o s t s a v i n g s a r e $.32/tonne a t a n o m i n a l m i n i n g c o s t

o f $1 .10/ tonne. T h i s new s y s t e m a l l o w e d t h e mine t o r educe

t h e t r u c k f l e e t by 25%. M o r e o v e r, a v e r a g e t r u c k r e q u i r e m e n t s

were r e d u c e d by 37%, w h i c h e l i m i n a t e s a l l t r u c k c a p i t a l

e x p e n d i t u r e s o v e r t h e n e x t t e n y e a r p e r i o d . I t i s e s t i m a t e d

t h a t a r e d u c t i o n i n a v e r t i c a l t r u c k l i f t o f o n l y 30 m e t r e s

c a n s a v e one m i l l i o n d o l l a r s o f o p e r a t i n g c o s t s p e r c r u s h e r

a n n u a l l y .


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5.3 Bingham Canyon Copp e r Mine

T h i s open p i t i n U t a h , U.S.A i s c u r r e n t l y

u n d e r m o d e r n i z a t i o n t o a c h i e v e a p r o d u c t i o n o f 70,000

to nn es o f o r e pe r d ay u s i n g i n - p i t c r u s h i n g and co nv ey o r

t r a n s p o r t . The s y s t em c o n s i s t s o f a s e m i - m o b i l e 1.5x2.7 m

(60-109 in . ) g y r a t o r y c r u s h e r a nd s i x b e l t c o n v e y o r s .

T he c r u s h e r we ighs 1,200 t on ne s and i s

i n s t a l l e d o n c o n c r e t e f o u n d a t i o n s i n a r e c e s s on a be nc h a t

t h e c o n v e y o r t u n n e l p o r t a l e l e v a t i o n . I t i s f e d by 154 ton ne

t r u c k s f rom two s i d e s . To t a l h e i g h t o f t h e i n s t a l l a t i o n i s

a p p r o x i m a t e l y 30 m. Ore i s c ru sh ed t o a s i z e o f 250 mm a t

a t h r o u g h p u t r a t e o f 9,000 t o nne s pe r hou r. The f e e d hoppe r

has a c a p a c i t y o f 600 m 3. T he d i s c h a r g e b e l t i s 3 m wide

and 26 m l o n g , w i t h i n f i n i t e l y a d j u s t a b l e s p e e d be tween z e r o

an d 0.5 m/s. Th e p l a n t i s e q u i p p e d w i t h a h y d r a u l i c c r a n e

o f 110 tonne l i f t i n g c a p a c i t y and a h y d r a u l i c r o c k b r e a k e r .

The mine u s e s s i x c o n v e y o r s o f a t o t a l l e n g t h

o f a b o u t 8.5 km. Th e l o n g e s t co nve yo r, wh i ch i s 6 km l o n g ,

r u n s t h r o u g h a t u n n e l e x c a v a t e d i n t h e p i t w a l l t o t he

s u r f a c e . A l l c on v ey o r b e l t s are 1.8 m wide. T o t a l i n s t a l l e d

d r i v e power i s 12,900 kW.


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5.4 G i b r a l t a r Mines

T h i s open p i t mine i n McLeese La ke , B.C.

p r o d u c e s 37,000 t o n n e s o f copper-molybdenum o r e d a i l y

f r o m f o u r p i t s . I n 1980, an i n - p i t c r u s h i n g a n d c o n v e y i n g

sys tem was i n s t a l l e d i n t h e E a s t P i t . Th e s y s t e m c o m p r i s e s

a 1.4x1.9 m (54-74 i n . ) g y r a t o r y c r u s h e r a nd t h r e e f l i g h t s

o f c o n v e y o r s o f a t o t a l l e n g t h o f ab ou t 10 km and l i f t o f

145 m. Cr us he d or e i s l o ad ed on to a s lo w spe ed 2.13 m wide

d i s c h a r g e c o n v e y o r , t h e n t r a n s f e r r e d onto a 1.5 m wide

t w o - f l i g h t o v e r l a n d c o n v e y o r t r a n s p o r t i n g o r e t o t h e

p r o c e s s i n g p l a n t . Av e r a g e c a p a c i t y o f t h e sys te m i s 1,8 00

to nn es p e r ho u r , and d u r i n g t h e l a s t f i v e y e a r s t h e s y s t e m

h a n d l e d 4 5 m i l l i o n t o n n e s o f o r e .


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5.5 I s l a n d Copp er Mi nes

T h i s open p i t a t P o r t Hardy, B.C., Canada

p r o d u c e s 43,000 t o n n e s o f c o p p e r o r e d a i l y a t a s t r i p p i n g

r a t i o o f 2 :1. I t i s a mine w hi ch c o n v e r t e d i t s a l l - t r u c k

s y s t e m i n t o i n - p i t c r u s h i n g a n d c o n v e y i n g .

The new system, i n s t a l l e d i n 1985, empl oys

a p o r t a b l e c r u s h e r s t a t i o n , and o u t - o f - p i t c o n v e y o r w h i c h

t r a n s p o r t s o r e t h r o u g h a n i n c l i n e d t u n n e l t o t h e s u r f a c e

f a c i l i t i e s . Was te i s s t i l l h a n d l e d b y t r u c k s .

T o t a l i n v e s t m e n t i n t h e e n t i r e system was

24.3 m i l l i o n CDN d o l l a r s ( s e e Ta b l e 2 ) , w i t h e x p e c t e d

s a v i n g s o f $ 0.19/tonne. The pay bac k p e r i o d i s 4 y e a r s

an d t h e t r u c k f l e e t was re du ce d fro m 25 t o 14 u n i t s .


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TABLE 2

CAPITAL COSTS OF THE CONVEYING SYSTEM

I s l a n d C o p p e r Mines

$ CDN

CRUSHER STA TIO N 7.6 m i l l i o n1.4x1.9 m (54-74 i n . ) g y r a t o r y p o r t a b l ec r u s h e r , r a t e d t h r o u g h p u t 2,550 tonne /h ;e q u i p p e d w i t h a h y d r a u l i c r o c k b r e a k e r,h o p p e r / f e e d e r , 50 t o n n e s l e w i n g c r a n e ,a nd d i s c h a rg e c o n v e y o r 30 m l o n gand 2 . 1 m w ide .

CONVEYOR TUNNEL 4.2 m i l l i o nl e n g t h 850 m, s i z e 4.25x3.65 m,i n c l i n e d a t 2 5%, l i n e d w i t h f i b r er e i n f o r c e d c o n c r e t e .

CONVEYOR 9.4 m i l l i o n1.37 m w ide b e l t , c a p a c i t y 4,500 tonne /h ;e q u i p p e d w i t h m a g n e t i c s e p a r a t o r ,v e r t i c a l t a k e - u p , an d 2980 kW d r i v e .

OTHER COSTS:D e s i g n E n g i n e e r i n g 0.4 m i l l i o nP r o j e c t Mana geme nt 0.5 m i l l i o nC o n t i n g e n c y 2.2 m i l l i o n

TOT AL COSTS: $ 24.3 m i l l i o n


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5.6 H i g h l a n d Va l l e y Copper

T h i s open p i t mine, l o c a t e d i n t h e H i g h l a n d

V a l l e y , B.C., p r o d u c e s 120,000 t o n n e s o f copp er /molybdenum

o r e p e r d a y f r o m two p i t s . R e c e n t l y , t h e Company h as

i n s t a l l e d two i n - p i t 1.5x2.2 m (60-89 i n . ) g y r a t o r y

c r u s h e r s f o r o r e c r u s h i n g , a t a c o s t o f $20 m i l l i o n .

E a c h c r u s h e r has a c a p a c i t y o f 6,000 t o n n e s / h a n d h a s i t s

own c o n v e y o r s y s t e m t r a n s p o r t i n g o r e t o t h e L o r n e x m i l l

o v e r a d i s t a n c e o f 2.5 km.


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6. IDLER SUPPORTED BELT CONVEYOR

The p r o p e r t i e s and c h a r a c t e r i s t i c s o f m a t e r i a l s

be ing conveyed have a major i n f l u e n c e on conveyor de si gn .

For a b e t t e r unders tanding o f problems a s s o c i a t e d with

conveyors, the f o l l o w i n g p r o p e r t i e s r e q u i r e d e f i n i t i o n :

The angle o f repose o f a m a t e r i a l i s t h e angle which

the s u r f a c e o f a normal, f r e e l y formed p i l e makes t o

the h o r i z o n t a l ,

The angle o f surcharge o f a m a t e r i a l i s t h e angle t o

the h o r i z o n t a l which the s u r f a c e of the m a t e r i a l assumes

whi l e t he m a t e r i a l i s a t r e s t on a moving conveyor b e l t .

T h i s angle u s u a l l y i s 5 t o 15 l e s s than t he ang le

of repose,

The f l o w a b i l i t y o f a m a t e r i a l as measured by i t s

angle o f repose and angle o f surcha rge, determine s the

c r o s s - s e c t i o n of the m a t e r i a l l o a d which can be c a r r i e d

s a f e l y on a b e l t . I t i s a l s o an index of the sa f e

angle o f i n c l i n e of the b e l t conveyor.


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The above p r o p e r t i e s a r e d e t e r m i n e d by

t h e c h a r a c t e r i s t i c s o f a m a t e r i a l , s u c h a s : b u l k d e n s i t y ,

maximum lump s i z e , m o i s t u r e c o n t e n t , a b r a s i v e n e s s ,

s t i c k i n e s s , t e m p e r a t u r e , and c o r r o s i v e n e s s .

B a s i c components o f t h e c o n v e y o r a r e :

b e l t , h e a d and t a i l p u l l e y s , c a r r y i n g and r e t u r n i d l e r s ,

t a k e up , d r i v e s , m o t o r s and b r a k e s .

6.1 B e l t

A c o n v e y o r b e l t c o n s i s t s o f t h r e e e l e m e n t s :

c a r r y s i d e c o v e r , c a r c a s s , and b a c k c o v e r . The p r i m a r y

p u r p o s e o f t h e c o v e r s i s t o p r o t e c t t h e b e l t c a r c a s s a g a i n s t

damage. B o t h c o v e r s a r e made f rom n a t u r a l r u b b e r s o r

e l a s t o m e r s . The c a r r y s i d e c o v e r , t h a t i s i n c o n t a c t w i t h

t h e m a t e r i a l , i s u s u a l l y t h i c k e r t h a n t h e b o t t o m c o v e r

( f o r c o a r s e o r e , 14 and 6 mm, r e s p e c t i v e l y ) .

The b e l t c a r c a s s c a r r i e s t h e t e n s i o n f o r c e s

when a c o n v e y o r s t a r t s and o p e r a t e s , a b s o r b s t h e impact

e n er g y d u r i n g l o a d i n g , and p r o v i d e s t h e n e c e s s a r y s t a b i l i t y

f o r p r o p e r a l i g n m e n t and l o a d s u p p o r t o v e r i d l e r s .


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High t en s io n ca r ca s se s employ a s i n g l e l a y e r o f s t e e l

c a b l e s . The s t e e l c ab l e s run th e l eng th of th e b e l t and

are he ld i n p l a c e by th e rubber .

The be l t width should be s e l e c t e d t o avo id

s p i l l a g e whi le l o a d i n g and conveying the m a t e r i a l .

For coarse ore b e l t s , i t i s d e s i r a b l e t o keep t he c ro ss

s e c t i o n a l l o a d t o l e s s than 80% of th e Conveyor Equipment

Manufacturers A s s o c i a t i o n (CEMA) s tandards ( F e r n i e , A.D.,

1985). T h i s means t h a t f lowsheet tonnage w i l l be 65 t o

70% o f CEMA. Peak tonnage can be as h igh as 85% of CEMA.

The c ros s s e c t i o na l l oad shou ld then be c a l c u l a t e d a t a 20

surcharge angle f o r 35 equal l eng th i d l e r r o l l s .

The maximum recommended b e l t speed i s 4 - 5 m/s t o avoid

m a t e r i a l s p i l l a g e .


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6.2 Pulleys

The pu l l ey s are of va r io us s i ze s and te xt ur es ,

but should be wider than the width of the b e l t . The pu l l ey s

are cons t ruc ted from s t e e l s h e l l s , e i t h e r bare or lagged,

f i t t e d wi th hubs and sea led bear ings . There a re d r i ve

p u l l e y s , snub pu l l ey s , and take-up p u l l e y s .

For high tension conveyors, the d r iv e pu l le ys

should have a heavy duty diamond lag gin g, and non -dr ivi ng

p u l l e y s a p l a i n l a g g i ng . A l l p u l l e y s f o r b e l t speed

exceeding 5 m/s should be turned, dynamically balanced,

and s t r e s s r e l i e v ed .

6.3 Idlers

I d l e r un i t s a re c l a s s i f i e d a s e i t he r c a r ry ing ,

r e tu rn , o r impact. The ca r r y i ng i d l e r s support a loaded

run of the conveyor b e l t , and re t u rn i d l e r s support the empty

re tu rn run of the b e l t . The impact i d l e r s support the bel t

dur in g mat e r i a l load ing . The i d l e r s may be the second or

t h i r d l a r g e s t investment i n a be l t conveyor system.

A t y p i c a l i d l e r system co ns i s t s o f th ree

r o l l s . One i s p lac ed h o r i z o n t a l l y i n the cen tre and the

other two are on the s i d es at opposing angles.


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The troughing angles can range from 5 to 4 5, depending

upon the angle of surcharge and the types of material being

handle d. In North America, a 35 angle i s ap pl ie d f o r

coarse ore handling.

An i d l e r which i s common on the con ven tio nal

conveyor b e l t system i s the t r a i n i n g i d l e r . Th i s i d l e r

i s a troughing i d l e r equipped on both si de s wit h sm al le r,

v e r t i c a l , s p r i n g mounted i d l e r s which keep the b e l t a l igned.

The fu nc ti on of the i d l e r u n i t determ ines the

spacing of the u n i t . In ge ne ra l, impact i d l e r u n i t s have

the c l o s e s t spacing, whereas re tu rn i d l e r u n i ts are widel y

spaced. Spacing of ca rr yi ng i d l e r s l i m i t s the catenary sag.

The suspended (garland) i d l e r system, very

popular i n Europe, i s used on lon g ov er la nd convey ors, but

on slopes over 20% causes b e l t misalignment and exce ss iv e

wear, because the i d l e r s have a tendency t o change t h e i r

p o s i t i o n f req uent ly. I t i s a b a l l bearing, non greasable

i d l e r c o n s i s t i n g of three or f i v e r o l l p r o f i l e s .

The suspended i d l e r i s t o l e r a n t of both poor ali gnment and

abuse by lumps because of the f l e x i b l e connections between

i d l e r s . I t can be fur ni sh ed wit h a qui ck re le as e type

of mounting which permits the e n t i r e i d l e r to be replaced

whi le the conveyor i s opera t ing.


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6 . 4 Dr ive Uni t s

The dr ive equipment b a s i c a l l y c o n s i s t s

of a motor, speed reducer and d r i v e wi th torque c o n t r o l

d e v i c e s . The d r i v e u n i t s are u s u a l l y l o c a t e d i n the r eg ion

of maximum t e n s i o n at the d ischarge end, but i n th e case ofa s teep d e c l i n e they are p l a ced at the f eed po i n t and act

as a brake .

The tandem d r i v e which comprises two d r i ve

p u l l e y s at the head i s t he most common arrangement for long,

h igh capa c i t y conveyors . Each p u l l e y i s powered by one or

two motors . The tandem d r i v e reduces b e l t s t r e s s e s and the

p o s s i b i l i t y o f a b e l t s l i p . A t t e n t i o n must be p a i d to the

e l e c t r o n i c s y n c h r o n i z a t i o n of the tandem d r i v e t o preven t

damage to the system.

I t i s very important t o c o n t r o l the motor

torque a p p l i e d t o the b e l t wh i le s t a r t i n g the conveyor .

An exces s ive torque adverse ly a ff ec t s the. mat e r i a l s t a b i l i t y

on an i n c l i n e d b e l t , the b e l t i t s e l f , mechanical p a r t s and

motor. The wound r o t o r motor and f l u i d c o u p l i n g are two

most commonly used systems t o ob t a in a s o f t s t a r t for long

conveyors.


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The wound r o t o r motors e n s u r e a m u l t i s t a g e a c c e l e r a t i o n t h a t

p r e v e n t s o v e r t e n s i o n i n g o f a l o a d e d b e l t when s t a r t i n g t h e

c o n v e y o r.

C o n v e y o r b r a k e s a r e u s e d w i t h i n t h e motor

o r i n c o n j u n c t i o n w i t h t h e moto r. Dynamic b r a k e s u s e t h e

motor i t s e l f a s a g e n e r a t o r o r a t t e m p t t o r e v e r s e t h e

d i r e c t i o n o f t h e motor movement. D o w n h i l l c o n v e y o r s use

motor f o r dynamic b r a k i n g , backed-up by a f u l l m e c h a n i c a l

b r a k e f o r emergency u s e . U p h i l l c o n v e y o r s us e t h e one-way

b a c k - s t o p and b r a k e s a r e o n l y u s e d i f t h e r e i s a f o l l o w i n g

c o n v e y o r.


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6.5 A c c e s s o r i e s

The a c c e s s o r i e s t h a t ca n be u s ed w i th

an y conv ey o r b e l t s y s t e m i n c l u d e b e l t c l e a n e r s , v a r i o u s

d e t e c t i o n d e v i c e s , and e n v i r o n m e n t a l p r o t e c t i o n c o v e r s .

The b e l t c l e a n e r s ca n be o b t a i n e d i n v a r i o u s t y p e s

and s t y l e s . The most common a r e b l a d e c l e a n e r s and b r u s h

c l e a n e r s .

A l a r g e s e l e c t i o n o f w a r n i n g and d e t e c t i o n d e v i c e s

i s a v a i l a b l e , s u c h a s : b r e a k d e t e c t o r s , o v e r t r a v e l d e t e c t o r s ,

p u n c t u r e d e t e c t o r s , o v e r l o a d d e t e c t o r s , and numerous t y p e s

o f w e i g h i n g and random s a m p l i n g e q u i p m e n t .

T he cov e r s u se d on con vey or sys tems rang e

f r o m w i n d s c r e e n s t o f u l l y e n c l o s e d c o n c r e t e s t r u c t u r e s .

T he t ype o f c o v e r depends on t h e c l i m a t e and t y p e o f t h e

m a t e r i a l moved.

L o n g d i s t a n c e c o n v e y o r s a r e e q u i p p e d w i t h

s a f e t y d e v i c e s w h ic h a l l o w t h e c o n v e y o r t o be s t o p p e d

i n c a s e o f emergency. The most common a r e p u l l c o r d

emergency s w i t c h e s . I n t h e c a s e o f power f a i l u r e th e

c o n v e y o r i s s t o p p e d by immedia te engagement o f t h e

b r a k i n g sys tem.


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7. CABLE SUPPORTED BELT CONVEYOR

T he c a b l e s u p p o r t e d b e l t c o n v e y o r s e p a r a t e s

t h e d r i v i n g an d c a r r y i n g f u n c t i o n s . I n t h e s y s t e m , t h e

d r i v i n g t e n s i o n s a r e t r a n s m i t t e d t h r o u g h two p a r a l l e l s t e e l

c a b l e s i n t h e f o rm o f e n d l e s s l o o p s , w h i c h c o n t i n u o u s l y

s u p p o r t a n d c a r r y t h e b e l t n e a r i t s e d g e s . The b e l t ,

t h e r e f o r e , i s n o t a f f e c t e d b y d r i v e t e n s i o n s a nd i s o n l y

d e s i g n e d t o c a r r y m a t e r i a l . The t w i n c a b l e s a r e s u p p o r t e d

by g r o o v e d l i n e p u l l e y s a l o n g t h e l e n g t h o f t h e c o n v e y o r,

w h i c h g i v e s t h e s y s t e m a p o s i t i v e t r a c k i n g .

7.1 B e l t

The b e l t c o v e r s have g r o o v e s f o r t h e c a b l e s .

T h e s e g r o o v e s r u n t h e t o t a l l e n g t h o f t h e b e l t and a r e

u s e d a s g u i d e s f o r t h e c a b l e . Due t o t h i s f e a t u r e t h e b e l t

needs no e x t r a a l i g n m e n t u n i t s .

The b e l t c a r c a s s c o n s i s t s o f t r a n s v e r s e s t e e l

w i r e s and w i r e mesh. R e c e n t l y , s t e e l w i r e s a r e u s e d i n

p l a c e o f s t e e l s t r a p s . T h i s a r r a n g e m e n t p r o v i d e s t h e b e l t

w i t h c a r r y i n g s t r e n g t h and f l e x i b i l i t y .


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7.2 C a b l e P u l l e y s

Th e c a b l e p u l l e y a s s e m b l i e s a r e mounted

o n l i n e s t a n d s a n d a r r a n g e d i n t w i n c o n f i g u r a t i o n u s i n g

r o c k e r b a r s . The r o c k e r b a r s c an p i v o t h o r i z o n t a l l y and

v e r t i c a l l y t o f a c i l i t a t e c o r r e c t s e l f a l i g n m e n t w i t h the

d r i v e c a b l e s . A t e i t h e r e nd o f t h e c o n v e y o r , t h e b e l t i s

t r a n s f e r r e d f r o m c a r r y i n g t o r e t u r n an d v i c e v e r s a by a

s i m p l e d e f l e c t i n g u n i t .

A t t h e h e a d and t he t a i l , t h e C a b l e B e l t

c o n v e y o r ha s b e l t p u l l e y s s i m i l a r t o t h o s e u s e d w i t h the

i d l e r b e l t c o n v e y o r . A t t h e t u r n i n g p o i n t t h e c a b l e s a r e

removed f r o m t h e i r g r o o v e s and r e ve r s ed by s e p a r a t e v e r t i c a l

d e f l e c t i o n c a b l e p u l l e y s w h i c h d e f l e c t t h e c a b l e s i n t o t h e

g r o o v e s on the o p p o s i t e s i d e o f t h e b e l t .

F o r e a s y m a i n t e n a n c e , t he p u l l e y a s s e m b l i e s

c a n b e q u i c k l y removed and a re p r o v i d e d w i t h r e n e w a b l e

p o l y u r e t h a n e l i n e d r i m s known as p o l y r i m s .


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7.3 D r i v e U n i t s

One o f th e main f e a t u r e s o f c a b l e s u p p o r t e d

b e l t c o n v e y o r s i s t h a t t h e r e i s o n l y one d r i v e u n i t f o r

e a c h c o n v e y o r r e g a r d l e s s o f t h e l e n g t h . A d r i v e u n i t

c o m p r i s e s a t o t a l l y e n c l o s e d r e d u c t i o n g e a r b o x i n c o r p o r a t i n g

t h e d i f f e r e n t i a l g e a r a r r a n g e m e n t t o e q u a l i z e c a b l e speeds

a n d t e n s i o n s .

Twin c a b l e d r i v i n g w h e e l s , e i t h e r s u rge

o r Koepe whee l t y p e , p r o v i d e t h e d r i v e t o t h e c a b l e s .

C o n t r o l a nd b r a k i n g f u n c t i o n s a r e a c c o m p l i s h e d by

c o n v e n t i o n a l me thods . The d r i v i n g c a b l e s a r e t e n s i o n e d

i n d e p e n d e n t l y t o c a t e r f o r any v a r i a t i o n s i n s t r e t c h .

T h e t e n s i o n i n g a r r a n g e m e n t e n s u r e s t h a t t h e t e n s i o n s i n

e a c h c a b l e a r e t h e same. The b e l t i s t e n s i o n e d s e p a r a t e l y

f r o m t h e c a b l e s .


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7.4 S p e c i a l F e a t u r e s o f t h e Sys tem

T h e C a b l e B e l t c o n v e y o r h a s t h e a b i l i t y t o

n e g o t i a t e s udden changes i n t h e h o r i z o n t a l d i r e c t i o n , b y

means o f a n a n g l e t r a n s f e r s t a t i o n . T h i s s t a t i o n c o m p r i s e s

a d i s c h a r g e and f e e d a r r angemen t combined a t t h e i n t e r s e c t i o n

o f two f l i g h t s o f t h e b e l t . M a t e r i a l i s t r a n s f e r r e d f rom

one b e l t t o a n o t h e r b u t t h e d r i v i n g c a b l e s r e m a i n t h e same

f o r b o t h f l i g h t s and t h e i r d i r e c t i o n i s c h a n g e d by a s e t

o f h o r i z o n t a l c a b l e d e f l e c t i o n p u l l e y s mounted o n t h e a n g l e

t r a n s f e r s t a t i o n . O n l y one d r i v e u n i t i s n e e d e d f o r t h e

whole c o n v e y o r s y s t e m when t h i s a r r a n g e m e n t i s u s e d .


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7.5 H a r d Rock I n s t a l l a t i o n s

C a b l e B e l t c o n v e y o r s o p e r a t e w o r l d w i d e ,

b o t h o v e r l a n d a n d u n d e r g r o u n d , c o n v e y in g v a r i o u s m a t e r i a l s

i n d i f f e r e n t c l i m a t i c e n v i r o n m e n t s . Many a p p l i c a t i o n s hav e

been c o n s i d e r e d f o r ext reme l ow t e m p e r a t u r e c o n d i t i o n s ,

down t o -45C .

I n Canada, a t Algoma ' s George McLeod Mine

i n Wawa, O n t a r i o , a 4570 me t re l o n g c a b l e b e l t c o n v e y s t h e

c r u s h e d i r o n o r e f r om t h e u n d e r g r o u n d mine t o a p r o c e s s i n g

p l a n t o n t h e s u r f a c e .

A t Newmont M i n i n g Company, S i m i l k a m e e n ,

a 1980 me t re l o n g c a b l e b e l t c r o s s e s a 25% s l o p e down

t h e s i d e o f a c a n y o n , a n d t h e n t a k e s a r i g h t a n g l e t u r n

a c r o s s a 490 m s u s p e n s i o n b r i d g e t o t h e p r o c e s s i n g p l a n t .

T h e b r i d g e was s p e c i f i c a l l y d e s i g n e d t o c a r r y a c o n v e y o r

o f a c a p a c i t y o f 153 0 t o n n e / h o f c o p p e r o r e .


64/286

- 47 -

8. HIGH ANGLE CONVEYORS

Over t h e l a s t f i f t e e n y e a r s , d i f f e r e n t

t y p e s o f s t e e p a n g l e c o n v e y i n g s y s t e m s have been d e v e l o p e d .

T h e p o c k e t b e l t c o n v e y o r and sandwich b e l t c o n v e y o r have

f o u n d a p p l i c a t i o n i n open p i t m i n i n g .

8.1 P o c k e t B e l t Conveyor

A p o c k e t b e l t c o n v e y o r was d e v e l o p e d by

K o n r a d S c h o l t z AG Hamburg, W est Germ any. H i g h a n g l e p o c k e t

c o n v e y o r s u s e c o n t i n u o u s c o r r u g a t e d s i d e s k i r t s and r u b b e r

c r o s s c l e a t s v u l c a n i z e d t o a f l a t r u b b e r b e l t t o fo rm box

compartments f o r m a t e r i a l a l o n g t h e l e n g t h o f t h e b e l t .

The s p e c i a l s k i r t d e s i g n p e r m i t s c o n t i n u o u s b e n d i n g a r o u n d

p u l l e y s w i t h o u t f a t i g u e o f t h e c o r r u g a t i o n s . The s i d e w a l l s

r a n g e i n h e i g h t f r om 40 t o 400 mm. A c r o s s - r i g i d i z i n g o f th e

f l a t b e l t m i n i m i z e s d i s h i n g and r e d u c e s a g i t a t i o n o f t h e

c o n v e y e d m a t e r i a l . The b e l t i s s u p p o r t e d by c l o s e l y spaced

f l a t i d l e r s .


65/286

- 48 -

So f a r , p o c k e t b e l t i n s t a l l a t i o n s a r e l i m i t e d

t o c a p a c i t i e s l e s s th an 1,000 to nn e/ h. The o n l y e x c e p t i o n

i s t h e Algoma C e n t r a l R a i l w a y ' s s e l f u n l o a d i n g v e s s e l MV

"Agava Canyon", w i t h i t s new e l e v a t i n g sys t em. The sys tem

thesis in-pit crushing as an alternative ubc_1988_a7 r32.pdf

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