010 atkinson

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http://slidepdf.com/reader/full/010-atkinson 1/14

FL SH FLOT TION T O OKIEP COPPER COMP NY

R TKINSONM STROUD

O OKIEP COPPER COMP NY

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1 . 0 INTRODUCTION

Some 30 o f t h e copper i n f l o t a t i o n t a i l i n g s o f t h e

C a r o l u s b e r g c o n c e n t r a t o r a t O ' o k i e p Copper Company o c c u r s

i n t h e minus 12 micron f r a c t i o n . T h i s i s no t r e c o v e r a b l eby c o n v e n t i o n a l f r o t h f l o a t i o n and i s an i n d i c a t i o n o f

o v e r - g r i n d i n g i n t h e m i l l .

F l a s h f l o t a t i o n i s a method used

s u l p h i d e s i n t h e m i l l i n g c i r c u i t ,

to r e c o v e r c o p p e r

which r e d u c e s t h e

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

on t h e c y c l o n e u n d e r f l o w s t r e a m f e e d i n g t h e Secondary

M i l l . E a s i l y f l o a t a b l e s u l p h i d e s a r e t h e r e f o r e removed

e a r l y i n t h e m i l l i n g c i r c u i t .

O ' o k i e p Copper Company have b u i l t

which was i n s t a l l e d i n one of t h e

an e x p e r i m e n t a l u n i t

m i l l i n g c i r c u i t s a t

C a r o l u s b e rg M i l l . This s t u d y summar i ses t h e p e r f o r m a n c e

c a p a b i l i t i e s o f t h e c e l l .

2 . 0 B CKGROUND

2 .1 The M i l l i n g and F l o t a t i o n C i r c u i t a t C a r o l u s b e r g

The m i l l i n g and f l o t a t i o n s e c t i o n a t C a r o l u s b e rg c o m p r i s e s3 i d e n t i c a l m i l l i n g u n i t s . Each has a Pr imary M i l l i n open

c i r c u i t f o l l o w e d by two S e c o n d a r y M i l l s i n c l o s e d c i r c u i t

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

to t h e f l o t a t i o n s e c t i o n F i g u r e 1 ) .

The f l o t a t i o n

which i s f ed

s t r e a m s F i g u r e

p l a n t has two s i m i l a r

by t h r e e S e c o n d a r y M i l l

2 ) •

s e c t i o n s ,

cyc lone

each o f

o v e r f l o w

The p l a n t t r e a t s 125 000 t o n s of o r e each month a t an

average head grade o f 1,61 o f c o p p e r.

2 . 2 N a t u r e o f t h e Ore Tr e a t e d

The dominan t c o n s t i t u e n t m i n e r a l s o f t he ore b e a r i n g b a s i c

rocks a r e p l a g i o c l a s e , b i o t i t e and v a r i a b l e amounts o f

h y p e r s t h e n e .

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

commonly f i n e d i s s e m i n a t i o n s , b u t v e i n l i k e a g g r e g a t e s and

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

B o r n i t e p r e d o m i n a t e s o v e r c h a l c o p y r i t e w h i l e c h a l c o c i t e

o c c u r s as a r e p l a c e m e n t p r o d u c t o f , and fo rming i n t e r -growths w i t h , b o r n i t e . The p r e f e r r e d l o c a t i o n s f o r t h e

c o p p e r s u l p h i d e s a r e ; i n t e r s t i t i a l be tween s i l i c a t e

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

c l e a v a g e p l a n e s i n h y p e r s t h e n e and p a r t i c u l a r l y m i c a s .

Improvemen t s i n t h e g r a d e w i t h d e p t h i n t h e Deep Ore a t

C a r o l u s b e rg i s n a t u r a l l y d i r e c t l y r e l a t e d t o t h e

g r a v i t a t i o n a l s e t t l i n g o f t h e s u l p h i d e s ( B e u k e s , 1 9 8 9 ) .

2 . 3 he N a t u r e o f P l a n t Ta i l i n g s a t C a r o l u s b e r g

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

t h e p l a n t i s d e s c r i b e d i n Ta b l e 1 b e l o w.

Ta b l e 1 C y c l o s i z i n g A n a l y s i s and Copper

D i s t r i b u t i o n o f Copper Ta i l i n g s

Sample f rom O o k i e p Copper

S i z e F r a c t i o n

( m i c r o n )a t SG = 2 , 5 5

44

30

22

15

12

- 12

ead

Cu

(ppm)

2590

1662

1561

1427

1572

4200

Mass

D i s t

3 7 , 5

2 6 , 8

9 , 4

6 , 9

2 , 8

16,6

2637 a s s a y )

2403 c a l c )

Cu

D i s t

4 0 , 4

1 8 , 5

6 , 14 , 1

1 , 8

2 9 , 1

From t h i s t a b l e t can be s e e n t h a t i n t h e +30 m i c r o n

f r a c t i o n ,

c o n t a i n e d

59 o f t h e

i n 64 o f t h e

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

mass . Whereas a l m o s t 30 o f

i s

t h e

t o t a l c o p p e r i n t h e t a i l i n g s i s c o n t a i n e d i n o n l y 17 o ft h e mass w i t h i n t h e -12 m i c r o n f r a c t i o n . Hence t a p p e a r s

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

t a i l i n g s .

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P r e l i m i n a r y m i c r o s c o p i c e x a m i n a t i o n o f t h e c o a r s e f r a c t i o n

+30 m i c r o n ) t e n t a t i v e l y showed t h a t c o p p e r o c c u r r e d

m a i n l y a s b o r n i t e and t o a l e s s e r e x t e n t c h a l c o p y r i t e .

A p a r t f rom one o r two l i b e r a t e d g r a i n s i n t h i s f r a c t i o n ,

mos t o f t h e b o r n i t e and c h a l c o p y r i t e o c c u r r e d a s :

( i ) Very f i n e d i s s e m i n a t i o n s r a n g i n g f rom 15 m i c r o n down to

l e s s t h a n 1 m i c r o n u b i q u i t o u s l y i n c l u d e d w i t h i n s e c o n d a r y

s i l i c a t e m i n e r a l ( p r o b a b l y t a l c ) .

i i ) C o a r s e r g r a i n s c h a t t e d t o o r i n c l u d e d w i t h i n s i l i c a t e .

i i i ) More r a r e l y as i n c l u s i o n s w i t h i n m a g n e t i t e .

E x a m i n a t i o ne s s e n t i a l l y

o f t h e f i n e f r a c t i o n ( -30a s i m i l a r t y p e s i t u a t i o n

m i c r o n )to t h e

showedc o a r s e r

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

b o r n i t e and c h a l c o p y r i t e were p r e v a l e n t ( M a r t i n

O o s t h u i z e n , 1 9 8 7 ) .

3 . 0 FLASH FLOTATION TESTWORK T O§OKIEP COPPER COMP NY

3 . 1 Exp e r i men ta l F l a s h F l o t a t i o n Uni t

The u n i t c e l l ( F i g u r e 3 ) was b u i l t e n t i r e l y a t O o k i e p

Copper Company. I t c o n s i s t e d o f a c i r c u l a r v e s s e l w i t h a

c o n i c a l b o t t o m . The d e s i g n was m o d i f i e d and s c a l e d up f rom

t h e t e s t c e l l a t Black M o u n t a i n . I t i s t h e r e f o r e an

a d a p t a t i o n o f t h e OK s k i m a i r c e l l s .

The volume o f

mechanism to

3t h e u n i t was 2 , 8 m . I t

t h e OK 3 c e l l , d r i v e n by

has a

an l lkW

I m p e l l e r speed was 240rpm.

l h ol J _ u n i t p o s i t i o n e d u n d e r n e a t h t h p ~ y ~ l o n

4) •

s i m i l a r

m o t o r.

f e e d i n g

F r o t humber 1 S e c o n d a r y M i l l a t C a r o l u s b e rg ( F i g u r e

d e p t h was c o n t r o l l e d by a musc le v a l v e a t t h e b o t t o m o f

t h e c e l l . T h i s was h y d r a u l i c a l l y o p e r a t e d and was a l s o

d e s i g n e d and b u i l t on t h e Mine ( F i g u r e 5 ) .

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HydraUl ici s t o n

FIGURE

o

MUSCLE V LVE ON FL SH T ILINGS DISCH RGE

RubberRing

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3 . 2 E x p e r i m e n t a l Method

I n i t i a l l y , t e s t w o r k was c o n d u c t e d t o g i v e a q u a l i t a t i v e

a p p r a i s a l o f t h e f l a s h c e l l s e f f e c t , i e g e n e r a t i n g mass

b a l a n c e d a t a and compar ing numbers 1 and 2 S e c o n d a r y M i l l

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

t h e r e s u l t s r e s t e d l a r g e l y on t h e a s s u m p t i o n o f t h e

s i m i l a r i t y be tween t h e two s e c o n d a r y m i l l c i r c u i t s

( S t r o u d , 1 9 8 8 ) .

O p t i m i s a t i o n o f t h e f l a s h c e l l p e r f o r m a n c e was c a r r i e d o u t

by a l t e r i n g f r o t h e r and c o l l e c t o r a d d i t i o n s t o a c h i e v e a

c o n c e n t r a t e g r a d e o f 40 c o p p e r. T h i s i s t h e p l a n t

r e q u i r e m e n t f o r f i n a l c o n c e n t r a t e s . F r o t h d e p t h was

m a i n t a i n e d a t 15 mm by a d j u s t i n g a i r a d d i t i o n and m u s c l e

v a l v e p o s i t i o n . The c o l l e c t o r used was Sodium E t h y l

X a n t h a t e SEX), w i t h S e n f r o t h 6010 a s f r o t h e r . An a t t e m p t

was made to maximise copper r e c o v e r y. C o l l e c t o r and

f r o t h e r a d d i t i o n s were i n c r e m e n t a l l y i n c r e a s e d t h e r e f o r e

u n t i l m a rg i n a l e x t r a a d d i t i o n s o f c h e m i c a l s gave no e x t r a

c o p p e r r e c o v e r y. T h i s p o i n t was r e a c h e d w i t h a X a n t h a t e

and f r o t h e r c o n s u m p t i o n o f 0 , 3 and 0 ,16kg r e s p e c t i v e l y f o r

each ton o f f r e s h m i l l f e e d .

I n o r d e r to q u a n t i t a t i v e l y a s s e s s f l a s h c e l l p e r f o r m a n c e ,a s e r i e s o f t e s t s were u n d e r t a k e n t o compare numbers 1 and2 c y c l o n e o v e r f l o w s on number 1 m i l l i n g u n i t . S i n c e t h i s

i s f l o t a t i o n f e e d , i t i s where t h e e f f e c t o f f l a s h

f l o t a t i o n would most r e a d i l y be a p p a r e n t . The samples

t a k e n a round t h e c i r c u i t were g r a d e d , c y c l o s i z e d and t h e

s i z e f r a c t i o n s a s s a y e d .

Sampl ing was c a r r i e d o u t o v e r a 12 day p e r i o d w i t h t h e

c e l l r u n n i n g c o n t i n u o u s l y and samples t a k e n t w o - h o u r l y to

p r o v i d e l _. 1 . .U d L LY c o m p o s i t e s

3 . 3 R e s u l t s and D i s c u s s i o n

Table 2 below summarises the t o n n a g e and a s s a y r e s u l t s f o r

number 1 m i l l i n g u n i t f o r t h e 12 day t e s t p e r i o d .

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Table 2 Tonnage and Assay Resu l t s f o r Flash Cel l Tes t Pe r i od

No 1 Mill Uni t Mill Feed Copper in Flash Cone Copper in

Feed Tonnage Grade Mill Feed Flow Flash Cone

Day TPD) ( Cu) TPD) TPD (solids) TPD

1 1520 1 69 25 69 14 70 6,54

2 1540 1,70 26 18 19 49 8,10

3 1510 1 54 23 25 16 96 6 674 1510 1,48 22 35 14 20 5,65

5 1550 1 55 24 03 11 34 4,83

6 1560 1 59 24 80 18 82 5,92

7 1500 1 59 23 85 8,37 3,59

8 830 1 61 13 36 8,97 3,02

9 1300 1 66 21 58 7 93 2 2310 1570 1 67 26 22 8,32 3,36

1560 1 68 26 21 7 60 3,18

12 1580 1 61 25 44 10 98 4 37

Average 1460 1 61 23 58 12 31 4 79

The f i gu re s i n d i c a t e t h a t with an average feed

m i l l i n g un i t o f 23 ,58 tons of copper each day,c e l l was capable of removing 4 ,79 tons o f copper.

to thethe f l a s h

An impor tan t assumption made th roughout t h i s work was t h a t

of an even s p l i t of the Primary Mil l d i scha rge to the twoSecondary Mil l c i r c u i t s . Allowing t h i s and thep o s s i b i l i t y of reproducing the e x i s t i n g f l a s h c e l l

per formance i n c e l l s on the o the r Secondary Mil l c i r c u i t s

i t may be expec ted t h e r e f o r e t h a t 40,63 of the copperr e p o r t i n g to the m i l l s would be recovered by f l a s h

f l o t a t i o n .

Table 3 compares copper d i s t r i b u t i o n i n the va r ious s i z e

f r a c t i o n s of cyclone over f low samples t aken on number 1m i l l i n g u n i t dur ing the t e s t pe r iod .

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Ta b l e 3 C y c l o s i z e r R e s u l t s o f Cyclone Over f low S t reams

Number 1 Cyc lone vs No 2 Cyc lone C a r o l u s b e r g )

No 1 Cyclone Overflow No 2 Cyclone Overflow

Size

microns) Cu

Mass

D i s t ( )Cu

Dis t ( ) Cu

Mass

Dis t ( )Cu

D i s t ( )

45

- 45 40- 40 30- 30 22- 22 + 15

- 15 12- 12

Tota l

0,55

3,85

1,41

1,07

1,24

1,481,64

0,95

61,65

2,87

5,89

7,32

5,53

3,6913 ,05

35,90

11 ,64

8,768,24

7,20

5,7322,53

0,65

8,25

2,86

2,03

2,12

2,152,17

1,61

52,54

3,37

7,20

8,87

6,76

4,5616,71

21,23

17,27

12,77

11,17

8,90

6,0822,58

The d a t a s u g g e s t s a r e c o v e r y o f 41 i n t h e minus 12 micron

f r a c t i o n w i t h f l a s h f l o t a t i o n ,

i e [ 2 , 17 x 16,71) - 1 ,64 x 13 ,05 ) ] x 100

[ ]2 ,17 x 16,71)

The u n i t c e l l was commiss ioned i n June 1988. The o v e r a l l

b e n e f i t cou ld t h e r e f o r e be s e e n when compar ing r e c o v e r i e s

o f numbers 1 and 2 f l o t a t i o n s e c t i o n s from J u n e 1988

t h r o u g h December 1988. The two f l o t a t i o n s e c t i o n s were

i d e n t i c a l u n t i l new f l o t a t i o n c e l l s were commiss ioned on

number 1 s e c t i o n d u r i n g J a n u a r y 1989.

Ta b l e 4 summar i ses mon th ly a v e r a g e d r e c o v e r i e s f o r e a c h

s e c t i o n , June t h r o u g h December 1988.

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Ta b l e 4 Averaged F l o t a t i o n R e c o v e r i e s J u n e 1988

t h r o u g h December 1988 C a r o l u s b e r g )

Month

1988

No 1 S e c t i o n

Copper Recovery ( )No 2 S e c t i o n

Copper Recovery ( )

? . .June 8 9 , 0 9 8 8 , 7 9J u l y 8 8 , 3 3 8 8 , 6 2

Augus t 90 ,38 90 ,17

September 9 0 , 0 0 89 ,51

October 89 ,30 88 ,25

November 88 ,89 8 7 , 8 4

December 87 ,79 8 7 , 2 9

Average 89 ,11 8 8 , 6 4

T h i s r e p r e s e n t s an improvement o f 0,47 i n o v e r a l l

r e c o v e r y. With f l a s h f l o t a t i o n c e l l s on each s e c o n d a r y

m i l l t h e r e f o r e , r e c o v e r i e s a r e e x p e c t e d to i n c r e a s e by

( 0 , 4 7 x 3) = 1,41 o v e r a l l .

These r e s u l t s compare f a v o u r a b l y w i t h t h e 12 day t e s t

r e s u l t s . Ta b l e 5 i s an a n a l y s i s showing t h i s .

Table 5 Expec ted R e c o v e r i e s a t C a r o l u s b e rg w i t hF l a s h F l o t a t i o n , based upon Te s t R e s u l t s

Without

F l a s h F l o t a t i o n

F l a s h C e l l s on

each Uni t

p . .Heads ( Cu)

Cu i n Cone ( Cu)

eu i n Ta i l s ( eu)

R e c o v e r i e s ( )

1 ,61

1 , 4 30 ,183

8 8 , 6 4

1 , 6 1

1 , 4 50 ,183

[ 1 - 0 , 4 1 x 0 , 3 ) ] =

0 , 1 6 090

The f i g u r e s show a 1,36 improvement i n r e c o v e r y w i t hf l a s h f l o t a t i o n o v e r t h e e x i s t i n g s i t u a t i o n .

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4 .0 ECONOMIC EVALUATION OF FLASH FLOTATION

A p r o f i t a b i l i t y

f l a s h f l o t a t i o n

c e l l s would be

r e l e v a n t :

a n a l y s i s can be per fo rmed w i t h r e g a r d t o

a t O ' o k i e p Copper Company. A f u r t h e r 5

r e q u i r e d The f o l l o w i n g c o s t s were

Manufac tu re o f 5 C e l l s and M e c h a n i c a l s

P u r c h a s e o f e l e c t r i c a l s

( l l k W m o t o r s p l u s S w i t c h g e a r and C a b l i n g )

Blower (Rowden-Wade)

Muscle Valves

To t a l Cos t

Cos t

(R)

97 000

18 000

14 000

1 000- 1

R13 000

O p e r a t i n g p r o f i t a b i l i t y c o u l d be c a l c u l a t e d assuming a

m i l l e d t onnage o f 125 000 t o n s e a c h month a t a head g r a d e

o f 1,61 c o p p e r w i t h a 41 r e c o v e r y o f t h e 30 c o p p e r i n

t h e minus 12 micron f r a c t i o n This r e p r e s e n t s an

improvement i n r e c o v e r y o f 1,36 as shown i n Ta b l e 5 , o r

some 345 t o n s o f c o p p e r e a c h y e a r

M a rg i n a l e x t r a c h e m i c a l c o s t s were c a l c u l a t e d t o beR7 000 e a c h y e a r w h i l e m a i n t e n a n c e was e x p e c t e d to t o t a lR6 000 e a c h y e a r

Ta b l e 6 be low i s a p r o f i t a b i l i t y a n a l y s i s f o r f l a s h

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

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Ta b l e 6 P r o f i t a b i l i t y o f F l a s h F l o t a t i o n

a t C a r o l u s b e rg

Value of a d d i t i o n a l copper p roduced( 3 4 5 t a t R7 5 0 0 / t

S m e l t i n g , F r e i g h t and R e a l i s a t i o n

( S m e l t i n g R300/ ton F r e i g h t e t c

R 6 0 0 / t o n )

S m e l t e r l o s s (98 e f f i c i e n c y

O p e r a t i n g Cos t s ( e a c h y e a r )

Chemica l sMain tenance

To t a l

R70 000R 6 000

R76 000

M a rg i n a l E x t r a P r o f i t b e f o r e Tax

R

2 587 500

(310 500)

(51 750)

(76 000)

R 149 250

T h e r e f o r e t h e p r o j e c t c a p i t a l would be p a i d o f f i n l e s s

t h a n 1 month.

5 . 0 ON LUSIONS

F l a s h f l o t a t i o n does improve o v e r a l l r e c o v e r y of copper a t

O o k i e p Copper Company. On t h e s t r e n g t h o f t h e t e s t w o r k

c a r r i e d out on t h e e x p e r i m e n t a l u n i t t h e Company has had a

f u r t h e r 5 c e l l s m a n u f a c t u r e d .

Apar t from t h e b e n e f i t s ment ioned i n t h i s r e p o r t t h e s e

c e l l s t a k e a huge l o a d o f f t h e f l o t a t i o n s e c t i o n . T h i senhances t h e o p p o r t u n i t y of max imis ing e f f i c i e n c i e s i n t h ef l o t a t i o n s e c t i o n .

7/24/2019 010 Atkinson


.0 REFERENCE

Beukes , J . T. ( F e b r u a r y 1 9 8 9 ) . Notes on t h e N a t u r e o f

M i n e r a l i z a t i o n i n C a r o l u s b e rg Deep Ore . ( O o k i e p Copper

Company I n t e r n a l Memorandum).

M a r t i n , G . J .

M i n e r a l o g i c a l

O o k i e p Mining

S t r o u d , A M

and O o s t h u i z e n , E. (December 1 9 8 7 ) .

E x a m i n a t i o n o f Copper

Company. (Gold F i e l d s

Ta i l i n g s f rom t h e

L a b o r a t o r i e s R e p o r t .

(May 1988) . The Per fo rmance

E x p e r i m e n t a l F l a s h F l o t a t i o n C e l l a t C a r o l u s b e rg( O o k i e p Copper Company I n t e r n a l R e p o r t .

o f t h e

M i l l .

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