Note: Descriptions are shown in the official language in which they were submitted.
)5
~escription
PROCESS FOR 'l'HE RF,COVE~Y
OF INDIU~l l'RO~l L~AD-CONTAINING ~TEI~I~LS
Tecllrlical ~ield
-
05 This invention is a process for the recovery of
indium from lead-eontainin~ ma-terials, primarily ore
processinc3 residues. The process ineludes the separation
of indium from other metals in the residues, such as
zine, arsenic and antimony.
Bac]cgroun Ar-t ancl Prior ~rt Statement
Indium is useful as a component of low meltin~
alloys and solders, as a eoatin~J on wires or eonnectors
in electrieal cireuits, as a eomponent of infrared
deteetors, as a eoatincl for bearilltJs, and in eonnection
with solar ener~y. Since 1972, indium procluc-tion in the
United States }-las been c~enerally declinirl~ while im~orts
have increased. Indium is found in conunercial quanti-ties
in flue dus-ts, residues, and sla~s, primarily from zirlc
and lead processing.
United States Bureau of Mines Bulle-tin Number 55
(1956) describes a proeess for recoverin~ indium, alon~
with tin, from crude leacd bullion. 'I`he T?rocess involves
-the separatiorl of indium chloride from a ~round mi~ture
made by fusing indium, lead, zinc ancl tin chloricles. Thc
mi~ture is leached with sulfuric acid and allowed to
stand in eon-taet with metallie indium for preeipitation
of tin and lead. Indium is recovered from the purifiecl
filtrate by cementation with zine rods.
The reeovery of indium from lead-zinc smelter
dross is also deseribed in the same bulletin. The dross
is leached i31 sulfuric aeid, eemented from the puri-
fied solution by zine, and melted under sodium eyanide,
then refined, redisso]ved in aeid and electroplatecl.
~ )nitcd States ~3ureau oE Mines l3ulletlll Number 630
(1965) descLibes a proeess Eor recovering indium from ZillC
oxide fume recoverecl from lead blast furnace slag The
slacJ is lcached with dilute sulfurie acid to remove zinc,
05 then with stronger sulfuric aeid to clissolve -the indium.
Indium is tl-ell preeipitated Ly the addition of ~inc
oxicle and sodium bisulfite, and leaehed with a strong
sodium hydroxide solution. The preeipitate is redissolved
in eoneentrated sulfurie acid, and heavy metals are re-
moved with hydrocJell sulfide. ~luminurn is then addcd tocement an indium metal sponc3e.
This bulle-tin also describes a process for recover-
ing indium from the insoluble residue produced durinc~
leachincJ zinc oxide Lor the electrolytic Z:illC process.
Lead and residual zinc are removed by smeltin~ I`he
flue dust is thell processed by leaellilly zinc ancl re-
turnill(J the indium to the smelter where it cloes into tlle
lead bullion and the slag. 'l`he slag is processed by
slag fuming, leaching and returnillg the indium to the
smelter Indiulll in the bullion is recovered with the
bullion dross, whicll is retrea-ted for removal of copper
matte and lead, the slag containing 2.5~ indium, whic}l
is electrolytically increased to 20-25~. Fllrtller chemical
and electrolytic purifieation steps are then yerEormed.
~lso described in this bulletin is a process Eor
indium recovery from old platincJ solutions involving
separating silver, lead, eopE~er, cadmiuln, zinc alld
nic~el by suceessive aeidifications, Eil-trations, and
neutralizations, leaving a precipitate of indium, iron
and tin hydroxide, WhiCIl are dissolved in hydrochloric
acid, and the indium recovered by electrolysis.
Disclosure oE the Invention
Indium is recovered from materials such as lead-indium
smelter residues, which may also contain other metals such
,~ .
~ ",............ .
. . -- . . .
,' f: . ' , _ '
--3--
as arsenic, zinc, antimony, copper and cadmi~lm, by means of
an acid pressure leach with sulfuric acid to solubilize indium,
zinc, and the other metals, leaving lead sulfate in the residue
which may be returned to the smel-ter. The solution is then
contacted with a neutralizing material such as fresh feed in
order to leach additional values and raise the pEI of the
solution as necessary for solvent extraction or phosphate
precipitation. The solution is filtered and may be treated
with iron powder to reduce any ferric to ferrous ion and the
indium is recovered from the solution, preferably by solvent
extraction with an organic agent such as di-(2-ethylhexyl)
phosphoric acid (DEHPA), followed by hydrochloric acid stripping,
tributyl phosphate (TBP) extraction, and water stripplng.
Indium is recovered from the final strip solution preferably
by cementation with aluminum, or by precipitatlon with phos
phate or zinc dust. Indium is recovered from aluminum as a
95~ plus cake.
In accordance with the present teachings, a process is
provided for separating indium from a solution containing
sulfuric acid and at least one metal value selected from the
group arsenic, zinc, antimony, copper, cadmium and iron,
wherein the process comprises separating indium from the other
metal values by solvent extraction wherein the solvent
extraction agent is di-(2-ethylhexyl) phosphoric acid.
The raffinate from the first solvent extraction step
containing zinc, and usually antimony, arsenic, cadmium,
copper, and iron, may be further processed, such as by
neutrali~ing with calcium oxide and calcium carbonate to
precipitate the metal values. After filtration, the water
may be recycled to aid in filtration and wash of the residue
from the neutralizing leach. The metal-containing tails may
be sent to disposal.
Brief Description of the Drawing
The figure comprises a flow sheet of a preferred embodi-
ment of the invention._referred Embodiments
The process of the present invention is useful for
separating and recovering indium from lead-containing
residues, primarily smelter residues also containin(J
arsenic, zine, antimony, copper, eadmium, and iron.
~ typical sueh residue con-tains 0.2 to 0.35~ indiuln,
20-55% lead., 0.06 to 0.2~j copper, ~.5 to 10% zine, 10 to
05 12.5~ arsenic, 1 to 76 antimony, 0.5 to 1.5~ eaclmiurrl and
1 -to 3% iron. Typically the lead is present as lead
oxide.
~s an optional stepr -the feed material may be pre-
leached -to remove arsenie.
'rlle indiurn reeovery proeess is most efEieiently
conducted as a cyclic process wherein fresh indium-
lead material is first contacted in an aeid-eonsurmillcJ
leaeh with the aeidie solution from an aeid pressure
leaeh to be deseribed. This solution preferably contains
between about 200 and 300 yrams per liter of sulfuric
aeid, as well as indium, zine, and other metals solu-
bilized duriny the aeid pressure leaell.
The fresh feed material is contaeted with this
aeidic solution eontaining solubilized indium pri-
marily to consume enouyh of the aeid in the solu-
-tion to prepare it for a solvent ex-traetion proeess r
for reeovery of indium therefrom, or for other indium
reeovery processes. The solution aeidity attained
duriny this aeid-consuminy leach should be low enouyh
to make the solution amenable to indium recovery by
solvent extraction, preferably less than 100 grams
per liter }12SO4 and more preferably about 50 yrams
per liter.
The aeicl~eonsuminy leaeh is eondueted for a period
sufficient to aehieve the desired aeid reduc-tion, pre-
ferably for a period of between about 2 and about 4.5
hours, and more preferably for between about 3 and about
4 hours.
,::
'.. ~ ':
. ~
Preferab].y the acid consuminy leach is conduct(d
at atmospheric pressure at temperatures suficient to
promote the acid consumption reac-tion, preferably betweeri
about room temperature and about the boiling ternperature
05 of the solution, more preferably between about ~0 C and
about 100 C, and most preferably between about 90 C
and about 95 C.
To ac}lieve the desired p~-l the percen-t solids in
the leach should be adjusted accordiny to -the acid- r
10 consl1ming capacity of the feed material which is typi-
cally between about 750 and about 900 lb. sulfuric acid
per ton of feed (about 0.35 to about 0.45 grams sul-
furi.c acid per gram of feed). Preferably, therefore,
solids in the leach will be between about 35 and 45
15 percent.
Duriny this acid-consuming leach typically between
about 30 and 40~ of the indium in the feed will be solu-
bilized.
As an alternative to the acid consumincJ leach using
20 fresh feed material, the pil of the acidic solution can be
rai.sed with caustic agen-ts such as calcium carbonate,
however, this requires subsequen-t filtration -to separate
the liquid from the solids generated by the addition of a
caustic reayent, with high wash water requirements, and
25 results in losses of indium from solution.
When fresh feed has been used to consume the acid
in the indium-containing solution as previously described,
a liquid-solid separation is performed, followiny which
the solids may be washed with water. This water may be
30 recycled filtrate from the neu-tralization of arsenical
tails as shown in the flow chart.
The solids are -then further treated for extrac-tion
of up to 92% of the indium originally present in the
feed by a sulfuric acid pressure leach. Typically
35 indiuM in the feed is tied up in -the matrix of ~.he
. :,; , . .
.,
, .
3~
~,
leacl oxide ma-terial in -the Leed, and can be freed by
convertinc3 the oxides -to sulfates, t}lUS producing a lead
sulfate residue suitable for recycle to a lcad smc:Lter
or other lead extrac-tion process. This frec-ing and solu-
05 bilizing of the leach is pre~erably accomplisl-led by
leachincJ the Eeed material wi-th a solution contain:ing
sulfuric acid in a concentration preEerably from about
200 to about 600 yrams per li-ter sulfuric acid, and
more preferably between abou-t 200 and about 300 grams
per liter.
~he leach is conducted under pressure at tempera-
-tures above the boiling temperature of the solu-tion,
preferably at least about 150 C. I~ic3her temperatures
have not been found to be detrimental -to the process.
Pressures necessary to achieve the foregoing tempera-
tures and to promote the indium solubilization ran(3e
between about 50 and about 160 psig, and preferably be-tween
about 90 and 110 psig. Iligher pressures have not been
founcl to be detrimental to the process.
To achieve up to 92% indium extraction, it has been
Eound preferable to use between about 30% and about 40%
solids in the leach by weigh-t.
The leach is conducted for a period of time suffi-
cient to achieve the desired extraction, typically Erom
about 2.0 to about 4.5 hours, and preferably from
about 4.0 to about 4.5 hours.
The indium is kept in solution durinc3 the leach by
conducting the leach under oxidizing conditions, such
as oxyc3en pressure~ The oxyc3en demand is slight. It
has been found that indium solubilization is enhanced
when small amounts of pyri-te are added to the leach,
especially when the feed material is low in iron. The
pyrite is added in amounts sufficient to dissolve the
~.
~ . .
.~ ,. .~
_
~8~L05
necessary oxyge~ y forminy ferric ions ~hicll th~n servc
as the oxidant -to prevellt reprecipitation of the ind~ m.
Preferably the amount of pyrite used is from about 20
to about S0 grams per lltcr.
05 Indium extrac-tion is maximized when the acid con-
centration at the end of the leach remclins hicJh, p~eferably
between about 200 and about 300 yrams per liter sul-
furic acid, and mos-t preferably be-tween about 240 and
ahout 260 grams per li-ter.
Followinc3 -the leach a licluid-solid separation is
performed, ancl the solution may be recycled to the acid
consuminc3 leach such as with fresh feed as previously
described, or is treated by other means to raise the pH
-to a value suitable for indium recovery therefrom.
The solution leaving the acid pressure leach
may contain up to 92Qo of the indium, up -to 91% of the
arsenic, up to 44O of the antimony, up to 99~O of the
zinc, up to 99% of the copper, Up to 92% of the cadmium,
and up to 90O of the iron presen-t in the original feed
material. ~ssentially all of -the lead, tin and silver
remains in -the residue.
Similar extractions are obtained when the feed
material for the acid pressure leach is fresh feed as
opposed to the repulped solids from the acid-consuming
25 leach using fresh feed material previously described.
Following pll adjustment of the solution as pre-
viously described, the solution may be furtller treated
to prepare it for indium recovery by the addition of
iron powder as needed to reduce ferric iron to the
ferrous state, typically in an amount of from about 3
to about 40 grams per liter.
The solution is then processed for indium recovery,
preferably by means of solvent extraction. Typical:Ly,
the solution contains between about 0.2 and abou-t 0.4
, .. . .. ,.. _ _ _._ ~
~, , .
~ '~' ' -, -._
~r `~ -`
-~3
grams per liteL^ indium. Good separation of indium is ob-
tained with arsenic contents in excess of 25 yraIms per
liter, arItimony and iron in exc~ss oE 0.35 ~Jrams per liter,
and cadmium in excess of 2 grams per :Liter.
05 The solvent extraction process may be carriecl out
so as to achieve at least about 95~ extraction of the
indium.
The preferred extractant is di- (2-ethylhexyl) phos-
phoric acid (DE~IPA) in kerosene or a similar diluent.
ln The concen-tration necessary to achieve the desire(l ex-
traction is t~pically between al~out 0.1 and 0.6 mo:lar,
and preferably between about 0.25 and 0.35 molar.
The preferred oryanic to aqueous ratio is ~re-
ferably between about 0.5:1 and 1.5:1, and preferahly
about 1.0:1. The solvent extraction is performed pre-
ferably at temperatures between about 30 C and about
50 C, and preferably between about 35 C and about
45 C. Several stayes are required to reach the de-
sired extraction, and it has been found that three to
four stages, preferably four stages, provide the best
results, usiny a mix -time for each sta~e of preferably
about 5 minutes.
T}le loaded organic is then pre-ferably scrubbed
with sufficient water to remove entrained aqueous
impurities such as arsenic, preferably at an organic
to aqueous ratio of about 5:]
Following the DF~IP~ extraction, most of the zinc,
cadmium, arsenic, antimony and iron have been rejected
in the raffinate.
The loaded organic is then stripped for indium, pre-
ferably with I~Cl at a preferred concentration at leas-t
about 3.0 N. Lesser concentrations may also be used,
but are not as efficient in supplying the hydrogen
ions necessary to regenerate -the oryanic extractant
_9- ~ S
and dlsplace the inclium. The preEerred orgallic to
aqueous ratio for pcrforming this strippincJ stcp is
between about 2.0:1 and 3.0:1, and preferably a~out
2.5:1.
05 It is often desirable to produce a Einal less acidic
solution of indium for recovery of elemental indium by
cementation or other means. To produce a solution of
indium in water, the indium in the EICl strip solution
may be fur-ther extrac-ted with an agent such as tributyl
phosphate (TBP) which ma~ be stripped for indium with
water.
Preferably the TBP is used at a concentration oE about
50~ in a diluent SUCIl as kerosene.
The T~P extraction is performed preferably at a
temperature between about 30 C and about 50 C alld
preferably about 40 C, in two to four stages, as
necessary to extract essentially all the indium present.
The preferred organic to aqueous ratio for this eYtrac-
tion is preferably at least about 1:2, and more preferably
about 1:1.
Following the TBP extrac-tion, the loaded organic
may be stripped with water preferably a-t a pEI of between
about 2 and 4. The preferred reagen-t for this pll
adjus-tment is l-ICl. The preferred organic to aqueous
ratio for this water strip is about 2:1.
~ n optional method for treatincl the loaded l-l~l
strip solution resulting from the stripping of the
D~EIP~ extraction agent to make it less acidic is
to neutralize the solution with caustic to -the pre-
ferred pll for indium recovery of between about 2 andabout ~.
Indium is recovered from the final pE~-adjusted
aqueous solution preferably by cermentation with alu-
rninum sheet. The indium collects on the aluminum
sheet, and in orcler to ~romote slougllillg o~ of thc
indium from the aluMinum surface in order to rnaintain
.. .. .. ...
os
--1()--
a clear surface for continued cementa-tion, inclium concen-
tration in -the final strip solution should be allowed
to build up by means of strip solu-tion recycle or eva-
poration. Concentrations of between about 5 and 15
n5 grams per liter indium are preferred.
Indium may be recovered from the cement cake by
slouyhing or scraping into a cone bottom tank, and
periodically draining to a pan il-ter for filtration,
washiIlg and transfer to a forced air tray oven. 'L`he r
high purity cement usually contains 95~ or more indium,
about 0.03% antimony, about 0.05 arsenic, and about 1.5'
aluminum.
~ s alternatives to solvent extraction, indium may
also be recovered from the acid pressure leach solution,
which has been adjusted to pl-I at leas-t about 1.0 as pre-
viously described, by other means known to the art, such
as precipitation Wit]I zinc dust or as the hydroxide or
phospIlate. The method chosen depends on antimon~ and
arsenic levels in the strip solution, with the zinc
preci.pitation being preferred wheIl these metals are
present. The indium precipitate may then be fused Wit]l
sodium hydroxide and cast i.nto anodes for electrorefininy
in a sodium chloride electrolyte.
When the solvent extraction method of indium re-
covery is used, raffina-te from the DFIIT'~ extraction
step may be neutralized with calcium oxide and/or calcium
carbonate, -the la-tter screened to minus 200 mesh. Re-
mainiIlg metals are thus precipitated and may be sent. to
disposal followiny a liquid/solid separa-tion, while the
filtrate may be returned to aid in fil-tration and wash
of the residue from the acid consumption leach.
From the foregoing it can be seen -tha-t an inte-
grated process has been disclosed comprising several
novel steps in combination to provide indium e~-traction
... ..
s
from the feed composi-te o.E up -to 92Qo ~ recovery :Erom
solution of approximately 95~, with an overall r~covery
of up to 84%, and good rejection of all other metals,
including antimony.
J '_'.t''- ~ _
3~
-12-
E:XAMI'[~
NE'UTRALlZING I,EACII
~ neutra:Lizing leach was performed on 300 cJrarlls
of master composite Eeed havincJ the following compo-
0 5 S i-tiOIl:
Indium 0.30% Copper 0.1~26
~rsenic 10.7% Cadmlum 1.02%
~inc 3.49% I.ead 49.4O
Antimony 4.03% Tin 0.47%
10 500 cc of 250 grams per liter sulEuric acid plus re-
cycled pressure leach primary filtrate and wash was used.
The leach was perEormed for 2 hours at 90 C, and the
materials filtered. The solids were then repulped and
leached with 3G0 cc oE 250 c,rams per liter sulfuric
acid under oxyc3en pressure with a 300 cc per minute
o~ygen bleed. The materials were again fil-tered.
Results are shown in Table 1. Total indium ex-trac-
tion is given in the Table as indium in the resiclue
as a percent of indium in the feed material by weicJht.
1-`
.
'1 N
~ O -~
;rl r-l N
~:j ) O~
rl
~g
..
c~
O I_
U) ~ N
~N
~ + ~r
r
rl O ~
r~ (~ O t~
r-l ~ L ~1 r-l
~L~ U~ ~
~1a~ al u, ~
~, ~ ~r \
'~'~
U~ U~ Ln O
(I) nl r~ ~1
~1
O O
(_) Ll^l r-l
E~ ~_1 N
.
r-l r~l
N~ ! r~
~ :~ `~ ~ ~
U~ ~ ir~l
~ ~L~ ('~
r-J
r I
C.) ~ rl ~ a~
æ rl U~ cTl N (~;
~ r~
--13--
il8~
EXA~PLE 2
SULI;`URIC ~CID PRESSUR~ LEAC~I
Samples of the master composite clescri.bed in ~.xample
1 were leaclled witll sulfuric acid under VaryincJ conclitions
05 of ten-pc-~rature, pressure, free acid concentration ancl
pyrite adclition. A 300 cc per minute oxyyen bleed was
used :Eor tests 2 throuyh 5. Results are set forth in
Table 2.
. ~ . ~ ~ .
S
. ..~
co r ~o r~ o r~ r~
r~J r; o r; c~ c~; ~o ~o
r~ c~ a~ c~ c~ c~ cr~
r\
O r Lr~ r~ c~ ~
(r' 'tC~r1 C I ~'n r
r~x
~ In ~o ~1 r ~1
r ~ r~ c~ r~ o
r~ ro r~ c~ cs~
~D C~ O C~ LO C~ 'S
.......
~1 o~D cr~ rr~ c~ rx~ I
r~ r~ I~ ~ r~ r~
rr
,~ ~d
~t~ rtrl
,~ ~ r~ c~
tn r~ '`'J~ ~ o .n ~ ~r ~ o
o ~ _ I~ cx~ ~r ~r~ ~I L~ tn
r~Jr,~ ~ ~ (ls ~)
0~ rS
rn r~
~ ,~ .~
tn tn o o o o o o o t) O
rl) ~ L~ In o ~ ~ Inrrs ~
_
J~
~ r.~ r~
b~ '' n .n ~ In 1n ~
rl 1
d~ rn
r~ ~ o ~ cr ~r V~ ~3
r ~ r- r~
rJ) C \ O o o ~o r ~ ~o
r~ L~~ n 1~O rr~l r~
~: O
r~ r~ r n ~O r-- ~U 1:~
.rJ -~ ) ~ I ) tV O
rn rn tn rn rn rnrn P~
r~ r'l'r~ r~ rv ~ r¢v -~ :~
3~B81~5
L " .
I`XAMl'l,l: 3
COMI'AI~ISON L~:A('IILi:S FOR INDI~M F,XTI~TION
___ _
50 yram samples of master composite described in
Example 1 were leached w:ith: IICl and br.ine, followecl by
05 leacl sulfate precipitation with sulfuric acid in 'rest l;
mi~ed sodium chloride/calcium chloride br.ine w.ith sod:ium
chlorate in Test 2; sulfuric acid acti.vated with nitric
acid in Test 3; and ammonium sulfate in Test 4 (Usilly a
30 c3ram sample of master composite feed). Results are
described in Table 3.
. ~ ..,; ~ .
..
. ,, _~
. , = ,~
~ l~si
(I)
r~
Q rn~ 0~ r-l
r~
~ o~
u', I l,
~ r~ ~ ~r co
ù`~ ~ . .
CO o~ Ln o
o
~t) ~ ~D ~D I_
n; tn o o~ 1 u~
~ CO ~) ~I r- 1
r~ Ul L~ ~ ~r
0> o~ o~ ~
r ~ r~ ~!
H t~O O~ Ln ~O
CO In ~r ~
~n o ~ l
~i~ o
F~ ~! f~Ln ~1 t~lt`\l (~1
_, O
''1
r~3 c~ o o Ln Ln
E~ - ~ C~' l l o
o o~ ~r
'~_ ~ r~l ~ O
t~ ~ t~ ~r C~ ~ 0
O. \ ~ ~ tn~ ~ t~ 5~ t'3 t,
o ~ o o o o o
O o O o o Ln O ~ ~r
~l ~r t\l n ~ Ln ~ ~
u~ t~ ~
~r
U Pt~ ~ 0
~, C~ r~ o
~ \ O~r \ O O~r t~l
L', ~ tl~ C~ C~ tn O
c~ ~ .~ ~ ~ ~ æ
Z . ~ ,
r-~ ~r
.~ ~ ~
tn u~ U~ U~
,~
17
LX~ME'LI;` 4
Primary filtrate from a neutralizillcJ :Icach o~- thc
master composite oE l~xample 1, containinc3 76 c3pl 1l2XO~
and 0.674 c3pl In, 8.67 c~pl As, 0.379 c3pl Sb, 28.9 c~pl
05 zn, alld 1.94 c3pl Cd, was extracted with 10~ (0.3 N)
D~ll]?~ in keroselle at an orc~anic -to aqueous ratio of
0.71:1 in three stages. The loaded orc3anic was thcn
scrubbed wi-th 1 N l-ICl, at an orc3anic to aclueous ratio
of 5:1, then stripped with 3.0 N I~Cl at an orc3anic to
aqueous ratio of 2.1:1. Results are summarized in
Table 4.
0S
O i O Lt- ~J O 1~1 Cl~ t\l O r-l
~ O. . . ~ O. ~ ~ ~ O. ~. ~
t~l OCi )O O r-lr~1~ 0 0(~J Oa~ O O O
r Ia~ I-- ~r--IC~ r--¦
r I~01~ r-l ~Ln ~o r I
~i Q)o . . .o . . .o
,r~ r~ l ''' "'~'' ' '~ '~ I ~'' ~'
~) r I (~)~J'C~lr-l r I r-l r I C~l (~1
I
C~
a) rL~ O ~O r-l O ~r
a) ~)O o o . . .o
r~, r Ir-l O O rl~1 1-- 1-- ~J
~1 1 ~ r~
o
~)1-- ~ Or I O1--0 O ~1 r-l ~t' O
~r 5~O . . .. O~ . ~ . O
L1l U~ OCi) O Orlr~ ~Irlr-l O r-l (\I rl f~l O
~)r ~a~ o r- I
a~
P~
Inr-lr-l ~D OC;~~Ir~lO O r~ r i O
U~ O . ~ ~ ~O ~ O
O CO O O r-l r-lt~O O Or-l C\l O O C>
r-l a~ o o
r~ r-l
a~~r ~ ~r ~r-l~O ~) CO 1~ 1_
~1 0 . . . .O .. . . O
r- I Or 1';J' a~ Or ~o ~ ~ O ~o r I CC ~)
~~o a~ r~r-l r--CCr-l r-l ~ a~
r~ 0~O 0~O u~
~: ~
~ o o o
r 1 ~ r r
U U
.~ ,~ ~)
~1 rX r~
,~Lr)LnC~~ ~Da~ o o Ln a~
o ~oCl~1-- t~lt~ ~ . t~
O 1~1~ r-Jr ~ r~t~') Lr) Ll ) ~0
~> ~ O Or-l ~r r I r-l
r~r-lr-l r-l
,1 ~
o
E~
~ O ~ O _~ O
U ~ tl) Z'; ~ tl) Z ~I tl) Z
~) rl 1~ ~ r-l ~ ~ r-l
. ,~ _ rl (1~ ~ rl rd
O ~ 1~ ~. ~ 1 ,r
~i .r~ Q n, ~ Q n, ri Q
P~ r~ rl ~ L~ rl ~tJ L~ ~ ~
a) rd U 11 a) rd O ~ c) rd U .LJ
h ~ U~ rl7 rl, ¢, U~ r,~ h ¢. tl~ U~
~1
rO r-l (~1
E~
~:~o-
~:X~ll'L,~ 5
Strip solution yenerated ~rom the procc~dure descri.bed
in ~ample 4, and containillc3 0.795 ypl In, 0.01 qpl As,
0.010 ypl Sb, 0.013 ypl Zn, 0.001 cJpl Cd and 0.232 clpl
Fe was e~-tracted with 50~ TBP in kerosene at an or(;anic
to aqueous ra-tio of 1:1 i.n two stac~es. I`he loadecl
orcJanic was then stripped wi-th water adjusted to pll
2-4 with IICl in two stayes at an orc~anic to aqueous
ratio of 2:1. Results are sum~larized in I'able 5.
r~
- ~ .
. .~
~8~ S
t~r
L. Or-lCOCT~ O~D ~ r o r-l 1(~ Cr~
I~ C~ . . .O . . . O
r-l ~11(~ Cl~r-J In ~:1' ~r r-l r-1 ~:) L~
r-l Or~ r~S~r-~ ~-1 1~ r-~
LJ
a) a) O1--L~l r~ OCi~~r r-~ O CT~ r-l r-
o . . . o . . . o
r-lr-l LnC~) r i O 1-- CT~ r-l O r~l
c~ r~ CT~ ~D cr~ ~D C~
r~
~) r~ ~ O O O O Ul O
r~ ~) O O O O I o I o
~ r~ r-l O r-l I--1 ~_1
o
L~
(1) ~ o o l-- o o o Ln o o o o o
U U~ O ~ ~ ~ O ~ . ~ O t~) C~
!-1 r-l Or.~ O r-l Or,o Or-l r--l
~ Ln r~Ln ~r
P~
u) oo o o o o o o o o c~ o
,,... o o o o o
r--lr-l O O r-l r~ O Or~ r~
Ln
r
o ~1 r. o 1-- o ~D Ln ~r o ct) ro
~ H O. . . O . . . O
1~ r-l Ln o ~rr I r~L(') Or-l r~) r~'~ LD
E I c~ c~ CT~ cr~ r-l I
o\o o~o o\o
L~ L~ L
r~ ~ r~
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U U
5~ ~1 (~
.J
x L~rll r,l
r-l Ln lr) Ll^~
O ~I r I O ~ r
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CS~ CO~D CT\C5`\~D r\J ~Ir I
r~
o
E~ L~ ~
O O U
a) ~ o
. tr
~) ~ - r l~, r~ ~
0 1~l L~ ~-1 L 1~l L'
~ ~ r i~ ~ ~1 ~ r-l n,
rd rd L~r~ rdLl I~rl rd L~-~ r~
O O~ q~ L~ ~1 (1)
~-~ 1~ Q) Id ~) O (~,1 )
Pl r,, P;u~ h P~ h P~tn
r~
-21 -
