Note: Descriptions are shown in the official language in which they were submitted.
~WO 951Z8502 2 1 8 7 8 9 2 PCT/A
T - n~ of a ~I~;tnn; ' ~ ~r;nl
The ~resent invention relates to the removal of
impurities from a t;e-n;forous materi-1.
.
The term "titaniferoua Aterial" is ~1~ ~Lood
herein to mean a material whiah c~-~ntA; nq at leaat 2 wt%
titAni
In a l?articular ~ ; the preaent invention
yrovides a proaesa whereby silica and alumina are re~oved
10 from a t;t~n;foroua material using an aqueoua leach in the
~,L.se~ce of acid, with the effectivene3a of the leach in
removin~- these impuritiea ~ A by the - n_t;r~n of
~Le~ e q and the c~nA; eion~ of the leach.
In induatrial chlorination processea titanium
15 dioxide bearin,-" fe4A~to-l~q are fed with coke to
chlorinators of varioua designQ (fl--;A;- ~ bed, shaft,
molte~ salt), opor-tecl to a maximum t~ __r ~ in the
ran,,e 700-1200C. The at common type of induatrial
chlorinator ia of the fl~ ~A;- ~ bed deaign. Gaseous
20 chlorine is ~assed through the titania and aarbon bearin~
char~e, convertin~ t;t-n;~m dioxide to titanium
tetr~-hloride ~,aa, which is then removed in the exit ~aa
gtream and ~ ~ ~l_ Q~A to liquid tit_n; eotrAAhl~lride for
further pur;f;-At;~n and 3?rocoaE~;nsr-
The chlorination proceas as ~ nA~-to~ in
industrial chlorinatora i8 well suited to the converaion of
pure titanium dioxide feedstocks to ~;tAn;~m eetr~-hloride.
~}owever, moat other inputa (i.e. impurities in feedatocka)
CaU8e fl;ff;---lt;oq which greatly _ _1;-At~o either the
chlorination process itself or the 8~hao~ ont stagea of
C A_~At;~n and purification. The AetA-hod table provides
an ;nfl; -Ati~ln of the typeQ of proble~q ~n~o -n~orea In
21 87~q~
WO 95/2~502 PC r
-- 2 ^
~aaitiOn, each unit oSi inputs which does not enter proaucts
contribute~ ~ubE,tantially to the sr~n~ ~t;on o~ waEteE. for
tre~tment and A;'31;~ SO_ e inputs (e.g. he~vy_et~lE"
r~l;o~-tives) result in waste c~r;~;cAt;nn~ which _ay
5 require Epe~ t A; ~ 1 in nitored repoEitories.
Pre~erred input~ to chlorination are there~ e
hi~h srrade _aterial~, with the mineral rutile (at 95-96%
Tlo2) the Et ~uitable of pre~ent feeds. Shortage~ o~
rutile have led to the devel ~_ o~ other feedstockE.
formed by ~p5~ A~ng n~t~ lly occurrin~ ~1 ;te (at 40-60
Tio2), E,uch aa titaniferou~ slag (apprnY;~-~t~ly 86% TiO2)
and ~ynthetic rutile (varlouEly 92-95% Tio2). These
~g ~A;n5J pr~ceEE^~ have had iron re_oval as a prim ry
:EOCUE., but have ~Yt~n~d to re_oval of _ ~e and alkali
15 earth i_puritieg, as well aE. Eo_e ~-1 'n;~-m
-
2 1 8789~
o 95128502 ~ 3 ~ PCT/~Ug5/00222
t~l Chlnrin~tinn cnn(1~nc~tion Purification
Input
Fe, Mn Consumes Solid/liquid
nhl nri ne, chlorides
coke, f oul
increases ~ h,
gas volumes make sludges
Alkal i Def luidis e
&alkali earth f luid beds du~
metals to liquid
chlorides,
consu,m. e
chlorine, coke
Al Consumes Causes Causes
chlorine, corrosion corrosion,
coke makes
sludges
Si A~ t~c Can encourage May require
in duct dist; l l At; nr~
chlorinator, blockage. from product
reducing Condenses in
campaign part with
life. titanium
Consumes tetrachloride
coke,
chlorine
V ~ust be
removed by
.-h ~m; CA 1
treatment
and
distillation
Th, Ra A~ st~C
in
chlorinator
brichwork,
radioactive;
- causes
Ai cp-~c;ll
di~ficulties
W0 9S/28S02 2 1 8 7 8 9 ~ pcrlAu9sloo222
-- 4 --
In the l?rior ~Art 3ynthetic rutile ha3 been formed
from l ~tAn;fe~ro~n m;n_rAlA, e.g. ;l ;te, via v~riou..
techni~ue3. ~A~Anr~l;ng to the moat commAonly a~lied
techni"ue, a3 variou31y or-Arnt~d in We3tern ~u3tralia, the
5 titani~erou3 mineral i3 reauced wlth coal or char in a
rotary kiln, at t~ _ R in exces3 of 1100C. In thi3
?roce33 the iron content of the mineral i.. Aubatnn~;Ally
Al l; -- J . Sul~>hur addition3 are al30 made to convert
r n ~ impurit ie3 pAArt ially to ~ 1 rh; r . Fo 1 lowing
10 re~ At;nn the ~ roduct i3 cooled, 3~rA AAt~d from
A _ Q~; A t ~d ch~r, and then . ub j ected to a~ueou3 ; _ or
removal of virtually nll ~AnntA;n~d All;~A iron a3 ~a
rAhle fine iron oxide. ~rhe titaniAferou,, ~roduct of
t;nn ia treated with 2-5% a~ueou,, 3ul~huric acid for
15 "~; _pA~ f; nn oAf _ -8 and 30me reeidual iron. There i3
no sub3tantial 1 removal of A lkal i or A 1 1rA l; n ~
earth3, Al n; ailicon, vanadium or rAA;nn-lAl;ArA, in
this ~roce. a na A;-A-lceed or or-ArAted. Further, iron ~nd
ne~e removal ia ;- _ lete.
~ecent A;AA,1. .. E~ have ~rovided a ~roce3a which
A~re~A~t~ reA--A~;nn at lower t _ ~ .a and ~rovide3 for
hydrochloric Acid l~Ah~n~ ~fter the a~ueous AorAt;nn 2md
iron oxide 83~-- t;nn ste~a. ~-~AA,rA;nU to A;~103~rea the
rroce33 i3 ef ~ective in removing iron, _ - - e, alkali
25 and All~Al;n~ earth i_;purities, a ,A.~hAtAnt;Al ~ro~ortion of
Alllm;n; inrut3 ~nd 80A vanadiumA A3 well a3 thorium. The
proce33 may be o~AAAAAt~d as a retrofit on ~ ;ng kiln
ba3ed ;nRtAll~t;nn~. However, the ~rocess i3 ineffective in
full vanadium removal and has little A1- '~AA1 i_pAct on
30 3ilicon.
In another ~rior art invention relatively hi,,h
de~,ree3 of removal of ~,~n~Aillm _ --B, iron and
;n;llm have been achieved. In one such ~rocA3s ;1- ;te
i3 AfirAt t-h~rr-lly reduced to suhstAnt;Ally ~ _lete
35 reA~At;nn of it3 ferric oxide content (i.e. without
-
~w09s~l8so2 ~ 1 ~3 78 92 PCr~Aug5~00222
s-lhat~nt;Al -~ll;Pat;nn), normally in a rotary lciln. The
cooled, reduced product is then leached under 35 p~ai
yreaaure at 140-150C with excess ?o% hydrochloric acid for
removal of iron, ~ m~ m;n;~m and r~ e. The
5 leach liquor~ are apray roagted for ,. ~ t;nn of
Lyd~ ~ chloride, which i~ recirculated to the lPArh;ng
step .
In other l?Loc~nc~ the ilmenite u~Se~,es grain
r~f;- by thermal nY;~t;nn followed hy thermal
10 reA--. t;nn (either in a f7.-;A;AeA bed or a rotary kiln) . The
cooled, reduced product is then subjected to r _~ ic
l~A~h;ng with exces~ 20% hydrochloric acid, for removal of
the deleteriou~ impurities . Acid ~ t; nn i~3 also
p~-f~ 7 by ~pray roa~ting in thi~ proce~s.
In all of the above ;nnod hydrochloric acid
h;ng baAed ~ ~cea~A impurity removal is similar.
Vanadium, Al~m;n;~m and silicon removal is not fully
e_fective .
In yet another procesg ilmenite i~ th~^l ly
ao reduced (without Al1;Pot;nn) with carbon in a rotary
kiln, ~ollowed by cooling in a nnnnY;A; s~inq ~.h~r6:. The
cooled, reduced ~roduct iB leached under 20-30 p8i ~auge
pres~ure at 130C with 10-60% (typically 18-25%) ~3ul~huric
acid, in the 3?` ~ Q of a #eed material which assists
25 hydrolysi~ of di~solved titania, and cnn~ n~ly as~i~ts
l~A~h~ng Of impuritie~. ~ydrochloric acid u~age in pl~ce o~
aUlphuriC acid has been claimed for this z~rocess. Under
such circum~tance8 5imilar impurity removal to that
~chieved with other hydrochloric acid based systema is to
30 be ~ect-~A. Where sulphuric acid is uaed rAtl;oA~t;vity
removal will not be - _ lete.
A commonly adopted method for upgrading of
ilmenite to higher grade products is to smelt ilmenite with
21 87892
Wo 95128502 PCrlAUgS100222
-- 6 --
coke ~ddition in ~n electric furnace, ~roducing a molten
titan$ferous sla~ (for c~sting and crushin5~) and a ~i~J iron
~roduct. Of the ~roblem im~uritie_ only iron iQ removed in
this manner, and then only incomrletely as a reQult of
5 compositional limitation8 of the ~rocess.
A wide rans~e of ~ot~Ant~Al feed_tocks i8 available
for -rgrA~;n~ to high titania content materials suited to
rhlar;n~ti~n . ~ _ lr~ of ~rim~ry titania sources which
cannot be E~t~QfArt^rily ~rgrnded by ~rior art l?`C-~88~-
10 for the u~ ~^~ of pro~ rt ion of a material suited to
rhl^r;nl~ti^n include hard rock ~non detrital) ;l- ;taQ,
R;l~reo~R ~ - rR, m ny ~rimary ( - -~hared) ;1- ;tAR
and large anatase resource_ . ~any such R e ~ ry gources
(e.g. titania bearinsr slags) also exist.
Clearly there is a r~nR~ rAh~e incentive to
discover methods for ll~srrA~inlJ of tit_niferous ~^-tar;AlQ
which can e: cAlly ~roduce high grade ~roduct3 alst
irres~ectively of the nature of the im~urities in the feea.
At ~resent ~rc,ll~ce ~ of titania ~igment by the
20 choride ~roce3s require feed_tocks to havs silica levels as
low as ~ossible. In general st fes~qQtocL-Q are less than
2% sio~. Where, for various reasons, feedstocks with high
levele. of _ilica may be taken in, they are blended against
other low _ilioa feedstoclcs, often with significant c08t
25 md ~roductivity prn~lt;~R. Therefore sll~l?l;ara of
titaniferous feoARtocl~a for rhlor;n~t;^n traditionally
~elect ores and c, ~ ~ ~.trR which will re~ult in
bonaf;riAtr~l ~roduct~ with low levels of silica. This is
gQnr~rAlly achieved by mineral d~ ;n~J tachn;~ ~e baaed on
30 phyaical e _~rAt;~n~'. In these ~L-~28~oF it i8 only
r~e~-ihl~ to reject ae~ao~nt;J~lly the majority of free quartz
I~Articleg without gacrificinl7 L~ y of the valuable
titania minerals. ~ level of rn;narAlo~ir~ ly antrp~na~
~ilica will normally remain in titaniferoua c^nrantrAt~R.
~wo 95l28502 2 1 8 7 8 9 2 pC'r/Ai
In the ~ g ~A;n9 pL~ " for ilmenite to _Ynthotic rutile
- which ~re presently operrte~l, the removal of iron and other
major im~?urities result in a cnn~-~nt At;nn effect for the
silic~ which ~TAn~rh~t~R the requirement_ for ;l te
cnn- --ntr~t~R a_ feed_tock_ to ~rg ~A;n~ ~lant_. Silica i8
not removed by ny commerci~ rgrAAIng proce__.
rh~.m;cnl remov~l of _ilica from t;tnn;ferouR
cnn~ ~ntr~t~R and ~ d ~~t~r~l s can be achieved
theoretically by aqueoug ~n~h;ng under J~ l ;no
~nnA;tinna. However, when 8uch len~h;ng i3 attempted under
rr~ ticn~ conditions it has been found that the
effectivenes_ of the le~ch is reduced by form3 of _ilica in
the material which are not ~ hl~ to Alt~rnt;nn, i.e. are
inert to leachin~, or by ren-tinnn between _ilica which ha3
entered ~cl~;nn and other ~ _ R of the titaniferou-
m terial which result in the l?r~c;rit~t;nn of Rolid
_;1 C~o-R material. Thi8 pr~;rit~t;on thuR limita the
effectiveneRs of the leach in removing silica.
~hu8, in the l?rior art, _ilica and other
impuritie_ have been removed from tit~niferouR material3 by
aqueou_ le~h~nsr with very high e,.-~3n~ of _imple cau_tic
_~lvtil~ns, An eXCegg i3 n~c~8~ry to ~revent impurities
pre8ent within the t;tnn;ferous materiala (e.g. alumina)
from interferin51 with the effectiveness of the leach. In
some cases, the spent l~A~hJ~ntR, cnn~A;n;ng ---~-~n8~n of
unused reagent ~re directly AiR~rA~d~ Recycle of learh~nt
~imply has the effect of c~ t~ng <leleterious
impurities in the l~nr-h~nt and reducing the effectiveness
of the leach. The cost of the caustic l e^~hAnl in such
cases is l?rohibitive, ~ ;nlly when n~ rAl;~ stinn cost3
incurred for the purpose of liquor discard into the
environment are cnnRi~ red.
There is no prior art in eYistence or
cnnt~ t~A in which removal of 8ilica in a leach
WO 95/28502 21 8 7 ~ 9 2 PCT/AU95/00222
-- 8 --
c~n~ f~l in the ~ ~- - of ~cid il3 ;n~;~Af~cl to be
~ffective for the t . of titaniferous materials.
In sum~ry there i8 ~L~'F ' ly no industrially realistic
~rocess for the effective removal of silica from
5 titan~ ferous materials .
~ -cor~l~n~ly, the ~resent invention ~rovides an
indu~trially realistic proce~ for llr~JrJ~;n~ of
titaniferous materials, which ~rocess comprise~: the
following ste~
(i) a l?retreatment which haa the effect of
ron~Ar~n~ silica hl~ to le~rh;n~ under
the ~articular conditions of a ~ubsequent
leach, and
~ ii) an aqueous leach in the pL~ of an
acid, the conditions of which are chosen
such that silica whic~ enters so1~t; nn is
t hydrolysed or preci~itated ~8 a
~; 1 ; c~te .
It is ~LeLeLl_~ that ~>retreatment ste~ (i)
20 ;nrl~ an aqueous c~ustic f~~
It has been surprisingly discovered that the
~rocess of the invention can remove ~ilica, alumina and
other im~urities.
The tL~ ~ in ster (i) may include any
25 treatment which has the effect of ensurin~ th t the form of
the silica in the f;t-n; r~ous ---t~ l enterinS~ ste~? (ii)
is I hle to altAr~ti~n under the c~nA;fi~n~ of step
(ii). For example, the treatment may include ~f;n~ of
the tit~miferou~ m~terial to make a titaniferous slag. It
30 may lnclude roasting of ~he f I fnn~f~rous ---t~r;Al with
additives which h ve the effect in roasting of converting
21 87892
~Wo 9SI28502 P~T/AU95100222
c~nnt~;n~A silica to ~ At--~ or transferring ailica into a
glaasy ~hase . The treatment may also be an ~ 1 kA 1 i n~ leach
~_ ~ , with or without other additive_, which has the
effect of converting silica to ~ J~h~ or crystalline
5 ~;l;c-At~a. The LL~ may be a ~ 'nAt;r~n of these
L,. s or of these tr~t ~ and other tr~A a
which in r ' n~t;on have the de_ired effect.
Step ( i ) may be conducted in any suitable
eq~ , which equipment will de~end in part on the
10 method chosen to ~erform thi8 8tep-
8te~ ( ii ) i_ a leach conducted in the ~resence of~cid. Any ~uitable acid may be used, ;n~lvA;nSr hydrochloric
and _ul~huric acids, but also ;n~ A;ng weak acid~ such as
organic acid_ and sul~hurou_ acid. However, the leach _te~>
15 must be c~nA~ teA in such a manner that ~r~ itat; o~ of
silica to a solid ~reci~itate or gel is avoided. The _t
effective means of ensuring that hydroly_is is avoided is
by cr~nf~ t;na the leach at low solids densities, thereby
limiting the level of silica in the 8~ t;~n
The leach may be ~nA~ t~d in any suitable
A---- n~ ' . Tylpically it will be r ~nA~ teA in stirred t~mk
reactors. T,~Arhing may be cnnf1~t~i in lt;rl-~ gtage8 or
in a single stage, c~nt;n~usly or in batches. Solids and
liquids flows through l~A-h;nSI may be cocurrent or
25 counte .i~-_L. ~Aa~nta may be added atAg~wi~e to r^-;ntA;n
reagent strength throu5~h the leach or may be added in a
_ingle stage .
Solid/liquid E _ rAt;~'n may be C~nA~ t~d after
l~Ach;na in any suitable manner, ;nt~l~A;n5~ cycloning,
3 0 th; ~ n; nS;r~ f; l trat; ~n pressure f; l tr~t; ~n and
o~ntr;f~ At;r~n The s~ent leachant may be cycled through
leA~`hAnt treatment for the removal of iml?urities and back
into the leach. Alternatively, s~ent 1~A~ hAnt may be
WO 95/28502 ~ 1 ~ 7 8 9 2 pCT/A J9!
-- 10 --
A;~ l or ~?roceed to be used in other proceas stages.
J~lA;t;r~nl1 steps may be inco-~o-~Led into the
~rocess as desired. For example:
(i) The leach residue may ~Agg to further
~rocessing, e.g. hot acid leArh;ng for
the re~oval of impurities such as iron,
magnes ium and ~ e .
(ii) The leach residue may be wa~hed.
(iii) The leach residue may be driea and/or
cAl~-in~d and/or aggl~ t c'l.
(iv) Where 1~A-hnn1- is recycled a bleed
stream may be removed in order to limit
the c -~ n of ~articular
lmpuritie~ .
(v) A ~rol?ortion o~ the wash liquors may be
recycled as water make up.
(vi) The process may be p~-Jeded by "rS~r~1;nST
of the titaniferous material for the
removal of i~puritie~ such as iron,
~ ai and _ a~, and ~?artial
removal of Bilica ~nd alumin~.
(vii) S~ent ~A~ n~ and wash streams, whether
or not treated for silica removal, may
report to leach/ acid rQ~_norA~ n
circuit3 wherein any r-l;o~ctive
el ~ ~ removed in l~ h; nSr are
de~orted to a suitable l~olid residue.
Clearly there is great f 1~ ; h; 1; ty within the
- 21 ~7892
o95l28502 - 11 - pcrlAussloo222
proce3~- a~ A;~clo~d to a~~ ' te a wide range o~ _eed
materials, aff well as pretreatment, leach and eoll~t;~n
treatment c~n~;~;nna and ~ he process ~tel?s
herein may be inco "~ ted in any ~--;tnhle =er
into any other proce~s operated for the purpose of the
~-A;ng of titaniferous materi~
l~n
~le 1:
This example illustrate~ a multi stage
I?retl~ - fgl 1 l ~ by a leach in the ~ .,_ ce of acid
which has the effect of silica remoYal.
A titaniferou~ c~n~on~ ~te was ground, mixed and
~ggl ted with the AAA;~;on of 0.65% anydrou~ borax and
0.65% soda, ~dded a~ sodium cn~h~n~to, nd roasted with
char at 1000C. The - _-eit;on of the roasted product
~fter char ~nrn~ n i~ giYen in Table 1. The roasting wa~
cnn~ rteA to enhance the -h;l;ty of silica in the feed
to sub~equent lon~-h;n5r by fo~~t;r-n of a glassy pha~e.
The roa~ted material was subjected to le~-h;ng
with boiling 45 g~?I. NaOH in the ~ _CC of 45 ~L Na2B407,
1.8 gpI, sio~ and 0.66 gpL Al20, under re~lux at 5% solid~
~lensity ~or 4 hours. The le~ch re~idue (after solid/liquid
~ern~At;nn and washing) c~nfn;nod 2.53% sio2 nd 1.04%
Al20~. That is, silica and alumina removal was ineffective.
However, with the ~Y~-ort; ~m of inert ~ilica and alumina the
~orm of alumina and silica in the residue had been
converted to ~ m;n~ t~ of the fol~ thnid type.
The leach re~idue was then ~uhjected to room
t~ (25C) le~ch;ng with 100 slpl. ~lrh~o~ acid at
10% solids density for 30 minutes. After solid/liquid
~ern~ n and washin5r the residue of thi8 leach l nn~:~;n~A
~ 87892
WO 95128502 Pcr/AUs5/00222
-- 12 --
1.2% SiO~ and 0.3% Al~03. The preci~>itated Al~m;n~silicate
was . _ 1 et~l y removed .
~le 2:
A sam~ple of a ~luart~ bearinl7 titania c~ t~
5 wa3 fully nY;~ with air at 900C and then reduced in a
fl~l;A;--~, bed uging a hy~ /CO2 mixture such that the
l~inal state of virtually all c~ntn;n~d iron was the 2l
; intir~n state. A 700g sample of this c~ n-e (who~e
lit;On i8 recorded in Table 2) was then le~ched at
40wt% solids density for 4 hour~ at 175C in a ~ cl~;nn
made u~ by adding 242 g/L of 40% sodium s;l;cnte 8c~ n
(3.2:1 SiO2:Na20 weight basi~) and 15051/L of NaO!~.
A washed and dried aam~le of the leach residue
had the co~osition which i~ also recorded in Table 2. The5 _ajority of the residual silica in this _aterial wa~ ~ a
ium nl~m;nns;l;~te which has formea during the leach.
A 300g sample of the leach re~idue was leached llt
10% ~olids density for 1 hour at 25C in a Elol~ n of 5%
}~CL. After this cold acid le~ch a wa~hed and dried sam~le
20 of residue had the c- _-1it;~ln which i~ also recorded in
Table 2.
Clearly the ~cid leach had been ef f ective f or the
removal o~ silica de~o3ited as nl~ nte in the
initial leach.
21 8789~
WO 951Z850Z PCTI~
-- 13 ~
3~sa~ple 3:
Pellets of a ground titania slag ~a product of
ilmenite ~~t;nSr) having a co_position recorded in Table 3
were made u~ with addition of 1% Na2 B407 and ronsted at
1000C for two hours in a flow of 1:19 H2O/CO2 gas mixture,
to oxidise trivalent titania.
~ ~am~le of the ~ellet3 was then subjected to
l~ch;ng at 25wt% solids density with 20% H2~04 at 135C
for 6 hours. The analysis of the leach residue ~ .,L~ed in
Table 3 shows that there was neS~ ible removal of silica
in the acid leach.
A further sam~le of the ~ellets were ~ubjected to
~ rh nçr with boilin~ 100 snL NaOH for 6 hours at 10wt%
Elolid~ density at 165C. The ~ it;~n of the caustic
lQach residue is ~ aco~ 1 in Table 4. Bven at low slurry
;~ silica is retained as Al~m;n~ il;eAte due to
~t~a~ n of the ~e~ hJ~nt with alumina.
The caustic leached re3idue was subjected to an
acid leach with 20% HCL at 30% solids density for 6 hours
at reflux. The --~ n of the residue of acid leachin~J
i~ L~col-led in Table 4. The - ' n~tion of the caustic
leach treatment with the acid leach t~ ' had been
highly effective in the removal of silica in the Acid
leach .
21 87892
WO 95/28502 Pcrl~U9S/00222
-- 14 --
Table 1: C ~ ;nn of~ qlh~-~-lly p., ~F1-J Feed in Ex~le
1.
wt .%
Tio2 63 . 4
FeO 2 5 . 7
~io2 3 . 81
Al2O3 o . 83
Na2O 0 . 88
~gO 0.88
MnO 1. 10
other 2 . 0
Table 2: Con~ositions of Feed and Leach ~ in }Zxample
2.
Feed ~ n~ A~id LeAch
Leal:h Re3idue
Res idue
Tio2 65.7 66.4 67.7
FeO26.5 26.9 26.4
15sio2 3 . 1 0 . 94 0 . 37
Al2O3 o . 8 0 . 67 0 . 49
Na2O n.d. 0.2 n.d.
~o 1.1 0.88 0.88
MnO1.1 1.2 1.2
20 CaO n.d. 0.03 0.01
othert 1. 4 2 . 8 2 . 9
~N.B. ;n~lllA-~ water o~ hydra- ion.
~WO95/28S02 21 8 7 ~ 9 2 PCrlAU95100222 ~
Table 3: Compositions of Slag Feed and Acid Leach Re~idue
in Rxa~4ple 3.
Feed Slag Acid Leached Slag
Tio2 77 . 9 88
FeO 9.1 4.0
5sio2 2.8 3.1
Al2O3 3 .1 0 . 95
Na2O 0.08 0.05
~gO 4.8 2.15
MnO 0.24 0.11
10CaO 0.47 0.17
Other 0 . 5 1. 5
Table 4: Com~ositionR of Cau~atic Leach and S~ t Acid
Leach 17~3i~"913 in 13xam~le 3.
Caustic Leach Acid Leach
Re~idue Residue
Tio2 78.4 82.7
15FeO 9.1 7.7
SiO2 3.1 0.96
Al2O3 3.1 2.7
Na2O n.d. n.d.
MgO 4.8 4.8
20NnO 0.25 0.23
CaO 0.38 0.13
Other 0 . 9 0 . 8
