flotation of spodumene beryl ores
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8/10/2019 Flotation of Spodumene Beryl Ores
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FLOTATION OF SPODUMENE BERYL ORES
The
U S
Bureau of Mines has been experimenting with flotation pr oc es se s
to separate the spodumene-beryl ores mined at Kings Mountain
N C
The
succ ess to date as well as the present status of the process i s disc usse d.
Furth er experimentation i s underway and stud ies will be made on the milling
cos ts involved i n the flotation proc ess.
by James
S
Browning
T
e pegmatites of the Kings Mountain-Lincolnton,
N.C., ar ea constitute the l arg es t known domestic
re ser ve of beryl and spodumene. The reser ve i s es -
timated to contain 90 million tons of pegmatic ma te-
r i a l with 1,280,000 tons of reco ver abl e Li,O ( lith ia) as
spodurnene. The pegmatite s al so contain 0.4 to 0.5
pct beryl dissemina ted throughout the orebodies. The
pegmatites may contain a potential re se rv e of 240,-
000 tons beryl , equivalent to approximate ly 34,000
tons of BeO.
Different flotation methods for sepa rati ng bery l
from feldspar o r quartz, o r both, have been devel-
oped by various investigators .2-7 On the other hand,
published informa tion is limited on concentration of
spodumene-beryl ores. s the response of beryl and
spodumene to flotation is essentia lly the sa me , a
succ ess ful separ atio n of the two min era ls depends
upon use of a sele ctiv e depr ess ant o r a selective
collector fo r one of the mine rals .
Sev era l ye ar s ago, the U.S. Bureau of Mines, r e -
cognizing the need for developing
a
large domestic
supply of st rat egi c bery l, undertook stud ies to devel-
op improved methods of recovering this mineral.
Because of th e low be ry l content of the pegma tite s,
economic production of the be ryl entails
its
recov-
ery a s a byproduct of spodumene flotation. Thus,
the development of pr oced ures that would provide
for maximum recoveries of the spodumene,
as
well
as the beryl, was a pr ima ry objective of the studi es.
Test s w ere made on run-of-mine or e and spodumene
flotation tailing fro m the Foote Mineral Co. s spodu-
mene conce ntra tor at Kings Mountain (Fig. 1). Pe t-
rographic anal yses of the or e and flotation tailing
a r e given in Table
I.
Detailed analys es and examinations of the o r e and
tailings revealed that the beryllium was pres ent in
the form of a low-alkali beryl. The crysta ls wer e
smal l, rare ly la rger than 14-mesh diam, and were
clea r and colorless.
About 10 pc t of the Li 20 content of the o re was
pres ent in the mic a and feldspar components of the
pegmatite. In som e weathered ore s the associated
J .
S
BROWNING s Supervising Metallurgist, Tuscaloosa
Research Center, Bureau of Mines, U.S. Dept. of the Interior,
University Station, Ala . TP 61820. St. Louis Meeting, Febru-
ary 1961. Also published n MINING ENGINEERING, July
1961, pp. 706 708. Discussion of this paper, submitted in du-
plica te prior to Jul y 1, 1962, wi ll appear in AlME Transac-
tions Mining), 1962, Vol. 223.
clay s al so contained sm al l amounts of lithia. This
is typica l of pe gmatites in the Kings Mountain ar ea .
LABORATORY TESTS
In the past, a vigorous chem ical trea tme nt of the
spodumene surface s with acid or caustic soda has
been considered ess enti al for satisfactory sele ctive
flotation of the spodumene from the other mine rals
in pegmatites. Many tes ts wer e made during this in-
vestigation to determine if chemica l treatm ent of
the sp odumene could be elim inated in favor of a r e -
agent combination that would de pre ss the othe r min -
er al s while selectively floating the spodumene.
A
sim ple reagent combination and proces s was devel-
oped that gave bett er spodumene recovery and grade
of co ncentrate than the mor e elaborate acid or ca us-
tic treatment methods previously used.
The finely ground or e pulps w er e conditioned with
either a n ammonium, alkali, o r alkaline eart h lignin
sulfonate and sodium fluoride , and the spodumene
was floated and cleaned using oleic a cid a s the col-
lect or. The spodumene tailing was deslimed, con-
ditioned with sulfuric acid and coco amine acetate,
and floated to reje ct mica. The mica tailing was
thickened and conditioned with hydrofluoric acid,
then washed to rem ove the acid. The washed pulp
was conditioned with sodium hydroxide for pH co n-
tr ol , and the beryl was floated and cleaned with oleic
acid a s the collector. Table
I
summarizes the re-
sul ts of the labo rato ry tes t work.
About 77 pct of the spo dumene and 75 pct of the
beryl were recovered from the pegmatitic material.
The spodumene concentrate assaye d 6.1 pct Li20
and 0.01 pct BeO, and the beryl product as saye d 3.0
pct Li2 0 and 1.57 pct BeO. Similar r esu lts we re ob-
Table I Petrographic Analysis of Ore and Flotation
Toiling From Foote Mineral Co.
Mineral
Analysis c t
re Tailing
Spodumene
Beryl
Mica
Quartz
Feldspar
Other
Compos i te
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.
Fig I-Conc entrator at Kings Mountain N . C . w here
USBM
i s conducting re se ar ch on flotation of spodu-
m ene- bery l o re s .
t a ined in t es t s of four o ther pegm at i t es , two f rom
other de pos i t s in Nor th Caro l ina , one f rom Hi l l C i ty ,
S.D. nd anoth er f rom Val d Or , Quebec .
PILOT PLANT TESTS
Spodumene F lo ta t ion : Th e l abora to ry inves t iga t ion
was prom is ing enough to wa r ran t fu r th er t es t ing of
the spodumene f lotat ion s te p of the pro ce ss in a
smal l cont inuous f lotat ion pi lot plant wi th
a
capac i ty
of about 15 lb of d ry feed pe r hour .
T h e o r e w a s
cru she d to -1/4 in . , then wet ground cont inuous ly in
a
r o d m i l l o p e r a t i n g i n c l o s ed c i r cu i t w it h
a
r a k e
c las s i f i e r to over f low -48-mesh ma ter i a l .
T h e c l a s -
s i f ier overf low pulp was fed to
a
h y d r o s ep a r a t o r t o
remo ve c lay and th icken the pulp to 40 to 45 pc t so l -
ids
The hydro separa to r under f low was condi tioned
with
2
lb of sodium f lu or ide and l lb of lignin sulfo-
na te pe r ton of o re . The d i s chM ge f rom the f i r s t co
d i t ioner f lowed
to
a
second condi t ioner , where 0 .96
Ta bl e II. Laboratory Flota tion of Spodumen e Mica and Beryl
Product
Analysis Pct Distribution Pct
Weight
Pct L ip 0 Be0 Mica L ip0 Be0 Mica
Spodumene concentra te 19 2 6 1 0 01 0 4 77 4
3 9 2
Mica concentrate 6 0 0 9 0 01
94 5 3 6 1 3 89 0
Beryl concentrate
2 3
3 0 1 57
2 0 4 5 74 9 0 7
Beryl middling
0 9
0 6 0 28 1 0 0 3 5 2 0 1
Tail ing
1 6
0 3 0 01 0 8 14 2 14 7 9 0
omposite
100 0 1 51 0 05 6 4 100 0 100 0 100 0
Pounds per ton of ore
Spodumene Mica Bery l
Conditioner Cleaner Conditioner Cleaner Conditioner Cleaner
1st 2nd 1st 2nd 3rd 1st 2nd st 1st 2nd 1st 2nd
Lignin sulfonate
Sodium fluoride
O l e i c ac i d
Sulfuric acid
Coco amine ace tate
Hydrofluoric acid
Sodium hydroxide
Conditioning time min
Pulp pH
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Toble
I l l
Summarized Results of o Smoll-Stole
Continuous Spodumene Flotation Test
Plant to i l ing
7
Analysis Pct Distribution Pct
Weight Spodu- Spodu-
Product Pct L iz 0 Be0 mene L iz 0 Be0 mane
Spodumene con-
centrate 20.5 6.00 0.01 83.0 75.5 5.1 88.8
Flotat ion ta i l ing 71. 9 0.44 0.05 3.0 19.4 89.2 11.2
Hydro-separator
overflow 7.6 1.10 0.03 trace 5.1 5 .7
omposite
100.0 1.62 0.04 19. 1 100.0 100.0 100. 0
lb of o leic aci d per ton of or e was added as the spod-
umene collector. The pulp then was floated to r e-
cover a spodumene concentrate. The tailing fr om
the rougher cell s flowed to a single cell, operated
as a scavenger, to remove additional spodumene
from the floating tailing. The froth from this unit
was recycled through the last rougher cell. The
rougher concentrate flowed to a bank of flotation
cell s fo r three-s tage cleaning. Results of the con-
tinuous te st a r e summarized in Table
111.
The cleaner concentrate assayed 6.0 pct LizO and
accounted for a Liz recover y of
75.5
pct. The con-
centrate contained 83 pct spodumene by petrographic
analysis, represent ing a spodumene recovery of 88.8
pct. About 11 pct of the lithia
in
the or e was not
present as spodumene but was associated with the
mica, f eldspar, and clay.
Beryl Flotation: Small-scal e continuous tests were
also made to substantiate the laboratory test r esults
obtained on bery l flotation. Rather than tr ea t the
crude o re to remove the spodumene before the beryl
flotation, tes ts we re made of spodumene tailings be-
ing produced
at
Foote Co. s spodumene concentrator.
As the plant tailing contained unrecovered spodu-
mene, the purpose of the te sts was to rec over t he
bery l and spodumene together
as
a
bulk concentrate
that could be re -tre ated to produce enriched beryl
and spodumene products. This method was att rac tive
because it would enable recovery of additional spod-
umene from the pegmatite to pay par t of the re- treat -
ment cost.
A pa rt of the concentrator tail ing, containing about
150
lb of d ry feed per hour, was d iverted to the pilot
plant. The pulp was conditioned with 2 lb of hydro-
fluoric acid per ton of dr y feed for 5 min
at
a pH of
3.8. The conditioned pulp was then washed in a spiral
classifier to give a sand product for flotation and r e-
move the acid from the pulp. The washed sands were
admixed with water to produce a pulp containing
about
30
pct solids in the slu rr y; and then they wer e
conditioned with 0.9 lb of sodium silic ate, 0.3 lb of
sodium hydroxide, and 0.9 lb of o lei c acid pe r ton of
dry solids. The pH of the pulp was 7.3.
The pulp was floated to produce a rougher concen-
tr at e which was then triple-cleaned. The middling
product was retur ned countercurrently to the rougher
cells. The bery l concentrate assayed 1.25 pct Be0
and 4.45 pct LizO; about 87 pct of the beryllium and
66 pct of the lithia was recovered. The bulk concen-
tr at e also contained about 12.5 pct mica, 10.5 pct
feldspar, and 5.5 pct quartz. A simplif ied flowsheet
t
Hydrofluoric acid
Sond pump
Conditioner
Spiral classifier
Sodium sil ica te
Overflow to waste
Conditioner
Sodium hydroxide
F r
le ic ac id
1
Flotot ion ce l ls
I-stage scavenging
Flotat ion ce l ls
3-stage cleaning
L
a i l i n g
Beryl-spodumene concentrate
Fig. 2-Flowsheet fo r USBM process to recover
beryl-spodumene concentrates.
fo r reco very of the bulk beryl-spodumene concen-
trate
is shown in Fig.
2.
Batch Treatment: Because of the difficulty of pro-
ducing enough bulk spodumene-beryl concentrate
from the low-grade tailings for further continuous
cleaning tes ts, the recov ery of enriched beryl and
spodumene products was c arr ied out by batch re -
treatmen t consisting of th ree stag es, as follows: 1
rejection of the mica, 2 lotation of the spodumene
and 3 lotation of the bery l.
The bulk beryl-spodumene concentrate was con-
ditioned with 10 b of su lfur ic acid per ton of dr y
feed to remove the fatty acid collector from the
mine ral surf aces. After washing the pulp to remove
Tobl e IV. Flota tion of Mica Spodumene and
Beryl From Bulk Concentrate
Analysis Pct Distribdtion Pct
Weight
Product Pct Li z0 Be0 Mica Li10 Be0 Mica
Mica concentrate 13.1 1.89 0.28 94.5 5.6 3.3 94.2
Spodumene con-
centrate
55.7 6.60 0.33 0.5 83.6 16. 7 2.0
Beryl concentrate
13.2 2.57 6.37 2.4 7. 7 76. 1 2.4
T a i l i n g 18.0 0.76 0.24 1.0 3. 1 3.9 1.4
omposite 100.0 4.40 1.1 0 13.1 100.0 100.0 100.0
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