selective flotation of mica from pegmantites

8/12/2019 Selective Flotation of Mica From Pegmantites

1/4

S E L E C T IV E F LO T T IO N O F M I C F R O M P E G M T I T E S

by

J S

Browning and

R

B. Adair

T h e l a b o ra t o r y b a t c h a n d c o n t i n u o u s f l o t a t io n p i l o t

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

r e c o v e r i n g h i g h g r a d e m i c a c o n c e n t r a t e s f ro m w e a-

t h e r e d m i c a p e g m a t i t e o r e s o f A l a b a m a and Georgia.

T h e r e s e a r c h i n d i c a t e d t h a t c o m b i n a t io n s o f a n i o n i c

a n d c a t i o n i c c o l l e c t o r s m a y b e u s e d e f f e c ti v e l y fo r

f l o t a t i o n of f i n e size

m i c a f r o m w e a t h e r e d p e g m a t i t e

ores

I n c o n t i n u o u s t e s t s , c o n c e n t r a t e s co n t a in i n g 98.5

m i c a w e r e o b t a i n e d f r om t h e G e o r g i a p e g m a t i t e o r e;

t h e A l a b a m a p e g m a t i t e

ore

c o n c e n t r a t e s c o n t a i n e d

98.4 m i ca . T h e r e c o v e r i e s w e r e 91 a n d 89 r e s p e c -

t ively.

INTRODUCTION

T

h e p r i n c i p a l u s e s of f i n e g ro u nd m i c a a r e a s a f i l-

l e r i n w a l l b o a rd j o in t c e m e n t , a s a f i l l e r a n d s u r -

f a c e c o a t i n g f o r r oo f in g , a s a n in g r e d i e n t i n p a i n t s ,

a n d i n o i l w e l l d r i l l i n g m ud . T h e m i n e r a l h a s o t h e r

u s e s i n t h e m a n u f a c t u r e o f r u bb e r , w a l l p a p er , p l a s -

t i c s , w e l d i ng r o d s , e l e c t r i c i n s u la t i o n , h o u s e in s u l a -

t io n , a n d t e x t i l e s , a n d a s a n a n n e al i n g a g e n t i n m e t a l

t rea tment .

In recent years , more than 99 of t h e d o m e s t i c m i c a

p r o du c ed h a s b e e n s c r a p a n d f l a k e m i c a ( m i c a w h ic h

d o e s n o t m e e t s p e c i f i c a t i o n s fo r s h e e t m i c a a n d is

u s e d f o r p r o d u c i ng f i n e g r o u n d m ic a ). T h e r e h a s b e e n

a c o n t in u e d i n c r e a s e i n m i c a p r o du c ti o n f o r s e v e r a l

y e a r s , t h e 1 9 6 3 p r o d u c t io n o f s c r a p a n d f l a k e m i ca

to ta l ing 117,251 tons . '

Ground mica

is

o b t a i n e d p r i m a r il y b y c r u s h i n g a n d

m i ll in g p e g m a t i t e s a n d s c h i s t s . T o a l e s s e r e x t e n t ,

mica

is

p r o d u c e d a s a b y p ro d u ct o f k a o l i n w a s h i n g

a n d f e l d s p a r a n d s p o d u m e n e f l o ta t i on o p e r a t i o n s . T h e

p r o c e s s e s u s e d i n r e c o v e ri n g m i ca b y c r u s h i n g a n d

m i l l in g p e g m a t i t e s a r e g e n e r a ll y s i m p l e, c o n s i s t i n g

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

t ro m me l s c r e e n s t h a t s e p a r a t e t h e m i ca a n d g a n g u e

a t s c r e e n

sizes

c o a r s e r t h a n 6 - m es h. A s t h e s e pr oc -

ss s a r e d e s i g n e d t o r e c o v er o n l y c o a r s e m i c a , h i gh

J.

S

BROWNING and R.

B.

ADAIR are respe ctiv ely

Supervising Research Metallurgist and Research Metallur-

gist Tus cal oos a Metallurgy Research Center Bureau of

Mines

U.

Dept. of the Interior Univ ersit y

La

TP66F 28. Manuscript Octo bei 27 1965.

AIME

Annual

Meeting February 27 to March 3 1966 New York

N.

Y.

Discu ssion of th is paper submitted in duplicate prior to

December 15. 1966 will appear in IME Transactions

March 1967 and AIME Tra nsa cti on s 1967 vol.

238.

l o s s e s i n t h e p l a n t r e j e c t s a r e co mm on . L a r g e to n -

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

p l a n t s h a v e b e e n a c c u m u l a t e d i n a n u m b er of a r e a s .

M e t ho d s f o r t r e a t i n g s u c h p r o d u c t s w e r e d e v e l o p e d b y

the Bure au of Mines in 1941,2 but ha ve not been

genera l ly appl i ed . More recent ly , mica f lo ta t ion re -

s e a r c h h a s b e e n c o m p l e t ed a n d p u b l i sh e d b y t h e

Bureau of mine^.^ T h e s e m e t h o d s r e q ui r ed c o m p l e te

remova l of 150- to 200-mesh ma te r i a l s from t he f lo ta -

t i o n f e e d w it h c o n s e q u e n t f i n e m i c a l o s s e s .

L a t e r , t h e B u r e a u o f. M i n e s i n v e s t i g a t e d m e t h o d s f o r

r e c o v e r i n g f i n e s i z e m ic a f ro m p e g m a t i t e o r e s a f t e r

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

n o t s o d r a s t ic a l l y a s o r em o v e t h e f i n e s a n d s .

T h i s r ep o rt s u m m a r i z e s t h e r e s u l t s o f t h e s e s t u d i e s .

T h e p r o c e s s d e v e l op e d w a s e f f e c t i v e o n p e g m a t it e

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

the commerc ia l t rea tment of o the r mica-bear ing peg-

m a t i t e o r e s a n d f i n e r e j e c t s t h a t h a v e b e e n a c c u m u -

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

DESCRIPTION OF ORES

T h e o r e s u s e d i n t h e i n v e s ti g a ti o n w e r e o b ta i n e d

f rom the Dixie Mines , Inc . , Hef l in , A labama, and th e

Ruberoid Corpora t ion , Har twe l l , Georgia .

T h e s a m p l e f ro m A l a b a m a c o n t a i n e d m u s c o v i t e a n d

quar tz , wi th a h igh perc enta ge of c l ay , and minor

amounts of b io t i t e , kaol in , l imon i t e and tourmal ine .

T h e m i c a i n t h e o r e w a s e s s e n t i a l l y a l l m i n u s 4 - me sh

i n s i z e a n d w a s f r e e o f a t t a c h e d m i n e ra l g r a i n s .

T h e G e o r g i a s a m p l e c o n t a i n e d m u s c o v i t e a n d q u a rt z ,

wi th minor amoun t s of b io t i t e , kao l in , and l imoni t e .

T h e m i c a in t h e o r e , w h i c h w a s e s s e n t i a l l y a l l m i n u s

4 - m e s h , w a s l i b e r a te d .

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

i n T a b l e I .

THE ANIONIC CATIONIC

MICA FLOT ATION METHOD

P r e v i o u s i n v e s t i g a t o r s 2 h a v e r e p o r te d t h a t c om -

p l e t e d e s li m i n g o f m i c a o r e s a t 1 5 0 - t o 2 0 0 - m es h w a s

r e q u i re d p r i or t o f l o ta t i o n w i t h c a t i o n i c c o l l e c t o r s t o

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

fro m t h e o t h e r m i n e r a l c o m p o n e n t s . N u m e r o us t e s t s

w e r e m a d e a t t h e T u s c a l o o s a M e t a ll u rg y R e s e a r c h

C e n t e r t o d e t e r m i n e i f s o m e r e a g e n t c o m b i n a ti o n

c o u l d b e u s e d t o s e l e c t i v e l y f l o a t f in e r s i z e m i c a

w i th o u t c o m p l e t e d e s l i m i n g . T h e i n v e s t i g a t i o n l e d t o

deve lopment of a p r o c e s s u s i n g a s i m p l e r e a g e n t co m -

Society of Mining Engineers

SEPTEMBER 1966 277


2/4

Table I .

Petrographic Analyses of Alabama and

Georgia Mica Ores

Mineral Analysi s Weight Percent

Ore Musco- Kao- Bio- Limo- Tourma-

Location vite Quartz tin tite nite line Clay

Alabama 16.5

35.5 3.0 3.0 0.5

0.5 41.0

Georgia 15.0 73.0

2.5 2.0

1.5

6 .0

bination that gave a s good or bett er recovery of mica

and grade of concentrate than obtained in the com-

pletely deslimed process; in most ca se s recovery and

grade were superior.

Briefly described the proces s included conditioning

the finely ground ore pulps a t 35 t o 40 soli ds with

sodium carbonate and calcium lignin sulfonate and

floating the mica with a combination of anionic and

cationic collector^ ^^^^^ The separation was not

particularly sensitive to pulp pH; excellent mica

reco veri es were obtained in a pH range of

8 0

to

10.5.

Th e function of the sodium carbonate i s to retard

flotation of the gangue mineral s and control the pH of

the pulp. Th e exact mechanism of th e retarding action

of the sodium car bona te i s not known. It see ms prob-

able however that it s effective ness may be due to

removal and dispersi on of slim e coatin gs on the

mineral surfaces.

The mechanism of the retarding action of the lignin

sulfonate ha s not been definitely determined. It se ems

probable however that selec tive adsorption of the

lignin sulfonate a t gangue mineral su rfac es effec-

tively prevents adsorption-attachment of the collec-

tor at the se surfaces . On the other hand mica parti-

cl es being relatively devoid of adsorbed lignin sul-

fonate are free to react with collector and are thus

made floatable.

The lignin sulfonates are effective slime dis-

persants and may ai d flotation by a ssi sti ng in proper

removal and dispersion of slime coatings on the

mineral surfaces.

Anionic type reagents such a s olei c acid and com-

binations of olei c and linoleic ac id were found to be

the most effective collecting agents for floating mica.

Increased sel ectivity in the presence of sl imes was

imparted to anionic c olle ctor s by incorporating small

amounts of cationic amine acetate collecting agents

in the system.

Th e most effec tive ratio of anionic and catio nic

collector for mica flotation was 2 to 3 part s fatty

acid to

1

part of cationic collector. Any appreciable

change in the ratio decreased both the grade and re-

covery of mica.

EXPERIMENTAL RESULTS

Laboratory Batch Tests

Batch flotation te st s were

undertaken to determine conditions for s eparating

mica from the gangue minerals. Results of preliminary

tests using varying quantities and types of reagents

led to adoption of th e following procedure:

Th e tes t sample wa s ground in a laboratory rodmill

using Tuscaloosa City tapwater which had about 45

parts per million equivalent calcium carbonate total

hardness. The sample was stage ground in the pres-

en ce of sodium hydroxide to aid in dispe rsing and re-

moving clay sl imes and screened on a 28-mesh sc reen

until the screen oversize contained only pure mica.

After grinding the sam ple was partly deslim ed by

decanting to remove some of t he clay sli mes from t he

pulp. Th e pulp wa s conditioned at 40 solids in a

mechanical agitati on flotation cell for 5 minutes

with sodium carbonate and calcium lignin sulfonate

for dispersion of the pulp and retardation of gangue

minerals. Fatt y acid wa s then added a s a collector

and conditioning was continued for another 5

minutes

followed by an additional 1 minute conditioning with

amine. This was followed by flotation of the mica.

Th e mica rougher concentr ate was cleaned three times

to yield a final mica concentrate.

Summarized resu lts of th e te st s showing the grade

of co ncen trat e and mineral reco veri es of th e pegma-

Table

II.

Laboratory Flot ation of Mica Pegmatit e Ores

Mica

Anal y- Distri -

Weight sis bution

Product percent percent percent

Georgia ore

Oversize mica

7.2 100.0 48.3

Flotation concentrate 6.1 97.4 40. 3

Composite concentrate 13.3 99.2 88.6

Middling 4.2 14.8 4.0

Tailing

76.2 1 .3 6.7

Slime

6.3 2.0 .7

Composite 100.0 14.9 100. 0

Alabama ore

Oversize mica

6.4 100.0 40.6

Flotation concentrate 7. 3 97.8 45.2

Composite concentrate 13.7 98.8 85.8

Middling

6.2 16.8 6.6

Tailing

40.6 2.0 5.1

Slime

39.5 1.0 2.5

Composite 100.0 15.8 100.0

Con-

Con- Con-

di- di- di-

Rod- tion-

tion- tion-

m il l e r 1

e r 2 e r 3

Reagents, lb per ton of ore

Sodium hydroxide 1.5

Sodium carbonate 2. 0

Calcium lignin sulfonate 2. 0

Fatty acid ole ic linolei c) 0.8

Amine stearyl oleyl) 0.4

Conditioning time, minutes - 5 5 1

Pulp pH

9.2 9.1

278 SEPTEMBER 1966

TRANSACTIONS


3/4

t i t e o r e s fro m A l a b a m a a n d G e o r g i a a r e g i v e n i n

T ab le 11.

Continuous F lot ation Tests

G E O R G IA O R E -S m a ll s c a l e c o n t i n u o u s p i l o t p l a n t

t e s t s w e r e m a d e of t h e o r e t o c o nf ir m t e s t s d a t a o b-

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

T h e p l an t f l o w s h e e t t h a t w a s u s e d i n t e s t i n g t h e

G e or gi a o r e i s s h o w n i n F i g . 1 C a p a c i t y o f t h e p l a n t

w a s a b o u t 1 5 0 l b s . o f d r y f e e d p e r h o ur .

T h e m i n u s 4- m es h o r e w a s f e d t o a H u m p h r e ys s p i r a l

t o p a r t i a l ly c o n c e n t r a t e t h e m i c a a n d r e m o v e a l a r g e

p a r t o f t h e q u a r t z . I n a d d i t i o n t o r e j e c t i n g o v e r 6 3

b y w e i g h t o f t h e o r e w i t h a l o s s o f o n l y 5 o f t h e

t o t a l m i ca , t h e s p i r a l a l s o r e j e c t e d m o s t o f t h e

l i m o n it e in t h e o r e . T h e s p i r a l o p e r at i o n u p g ra d ed t h e

m i c a c o n t e n t of t h e o r e fr om 1 5 t o o v e r 38 .

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

wet-ground in a rodmil l equipped wi th a 30-mesh t rom-

m e1 s c r e e n . T h e g r i nd i ng w a s a d j u s t e d t o t h e p o i n t

w h e r e t h e t ro m m el o v e r s i z e c o n s i s t e d o f p u r e m i c a .

T h e m i n u s 3 0 - m es h t r om m e l u n d e r s i z e w a s d e s l im e d

b y a t w o - s t a g e d e s l i m i n g o p e r a ti o n t o r e m o v e c l a y

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

a b o u t 2 0 m i n u s 2 0 0 -m e s h . T h e p u l p t h e n p a s s e d t o

a c o n d i t i o n e r w h e r e t h e r e a g e n t s f o r pH c o n t r ol ,

q u a r t z d e p r e s s i o n , a n d t h e f a tt y a c i d a s t h e m ic a

c o l l e c t o r w e r e a l l a d d e d . T h e p u l p fro m t h e c o n d i-

t

Underflow

7

t

O v e r f l o w c - - B o w l r ke c l o s r ~ l ~ c r

Amine

Vibmtingr----Toiling- Flolotnon

cells

P l us 50-

mesh

o l ng Mi nus 50-

mesh F I o ~ a ~ i o n

ells

toi l ing 3-stage cleaning

Mica concbntrole

Fig. I-Fl owsh eet for Reco very of Mica from Georgia Peg -

matite Ore.

Table

Ill.

Results of Continuous Flotatio n Tests For

Recovery of Mica From Pegmatite Ores

Mica

Analy- Distri-

Weight sir bution

Product percent percent percent

Georgia ore

Trommel oversize mica

Flotation concentrate

Composite concentrate

Flotation tailing

Hydroseparator overflow

Composite spiral concentrate

Spiral tailing

Composite feed

Alabama ore

Trommel oversize mica

Flotation concentrate

Composite concentrate

Flotation tailing

Hydroseparator overflow

Composite primary classifier

sand

Spiral c lass ifi er overflow

Composite feed

Rougher

Flota-

Condi- tion

Rodmill tioner Cell

Reagent s, lb per ton of ore

Sodium hydroxide 1.5

Sodium carbonate 1. 9

Calcium lignin sulfonate 2.0

Fatty acid ole ic l inole ic) 8

Amine stearyl oleyl) 0.4

Conditioning time, min ute s 7 1

Pulp pH 9.2 9. 0

t i one r f l owed by g rav i t y t o a bank o f t h ree roughe r

f l ot a ti o n c e l l s w h e r e t h e a m i n e c o l l e c t o r w a s a d d e d

t o t h e f i r s t c e l l .

A

roughe r f l o t a t i on f ro th w as r e -

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

m i c a c o n c e nt r a te . T h e r ou g he r t a i l i n g p a s s e d t o a

v i b r a ti n g s c r e e n t o r e m o v e t h e p l u s 5 0 - m e s h m i c a i n

t h e t a i l i n g , w h i c h w a s r e t u r n e d t o t h e r o d m il l f o r a d -

d i t i o n a l g ri n d in g . T h e c o n t i n u o u s p il o t p l a n t t e s t a c -

coun ted fo r a r ecove ry of ove r 91 o f t h e mica p re sen t

i n t h e f e e d i n a p r o d u c t c o n t a i n i n g 9 8 .5 m i ca . T h e

s u m m a ri z ed r e s u l t s o f t h e t e s t a r e g i v e n i n T a b l e 111.

ALABAMA ORE-The f l ows hee t fo r con t i nu ous

t r e a tm e n t o f t h e A l a b a m a o r e i n c l u d e d g r in d in g , c l a s -

s i f i c a t i o n , c o n d i t i o n i n g , a n d f l o ta t i o n a s s h ow n i n

Fig . 2 .

T h e h i g hl y w e a t h e r ed p e g m a t i t e o r e w a s f e d t o a

b o w l r a k e c l a s s i f i e r t o p a r t i a l l y c o n c e n t r a t e th e m i c a

a n d r e m ov e a l a r g e p a r t o f t h e c l a y s l i m e s . T h e b o wl

r a k e c l a s s i f i e r o v e r f l o w c o n t a i n e d o v e r 3 5 b y w e i g h t

Society of Mining Engineers

SEPTEMBER 1966 279


4/4

Mica ore

Stomge bin

r

Bawl roke ciassif ier -+Overflow o woste

t

30-mesh trammel -Oversize mica

ndersize

Hydroseporotor -Ove rflow - To wost e

I

Underflow

Overflow piral c lass if ie r

odfum corbonate

Lignln sulfonate

Conditioner

A m ~ n e

-stage rough~ng

To l l ing Midd l ing

F lo ta t ion ce l ls

T o waste 4.sloge cleaning

Fig. 2 Flowsheet for Recovery o f

ica

from Alabama Peg

mati te Ore.

of the o re wi th a lo ss o f on ly 2 o f the to ta l mica .

Th e des l iming opera t ion upgraded t he mica con ten t o f

the o re f rom 16 to ove r 25 .

Th e bowl r ake c la ss i f ie r sand wa s g round in a rod-

mil l equipped with a 30-mesh trommel to produce a

pure mica t rommel over s ize . T h e trommel under s i ze

was des l imed by a two -s tage des l iming opera tion .

T he o re af ter g r ind ing and des l iming co n ta ined abou t

22 minus 200-mesh . Th e par t ly des l imed ore , a f ter

cond i t ion ing a t 40 so l id s , was f loa ted to r ecover a

mica rougher co ncen t r a te . Th e rougher conce n t r a te

was c leaned four t imes to p roduce a concen t r a te con-

taining 98.4 mica, with a recovery of over 89 of

t h e t o t a l m ica . T h e r e s u l t s of t h e co n t i n u o u s t e s t a r e

presen ted in Tab le 3 .

REFERENCES

1

Benjamin Petkof: Mica. BuMines Minerals Yearbook 1963

v.

1 ,

1964, pp. 813-829.

~ a m e s

.

Normen and R.

G.

O Meara: Froth Fl otation and Ag-

glomer ate Tabl ing of Micas. BuMine s Rep t. of In*. 3558 , 1941 ,

14 PP.

~ a m e s

.

Browning and Thomas

L.

McVay: Concentration of Fine

Mica. BuMines Rep t. o f Inv. 6223, 196 3, 7 pp.

4 ~ a m e s

.

Browning, Frank

W.

Millsaps, and Paul

E.

Bennett:

Anioni c-Catio nic Flo tati on of Mica Ores From Alabama and North

Car olin a. BuMines Rept. of Znv.

6589

1965, 9 pp.

Frank

W.

Mlllsaps and Jam es

S.

Browning: Fatty Acid Fiotation

of Mica.

U S

Pa t. pending, No. 320,576.

6

James

S.

Browning and Ralph B. Adair : F lota tion of Mica. U S

Pat. pending, No. 390,485.

280

S E P T E M B E R 966

T R A N S A C T I O N S

selective flotation of mica from pegmantites

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