Note: Descriptions are shown in the official language in which they were submitted.
2 1 7 1 1 8 5 PCT/AU9 1/00528
WO 95/07366
~PGRADING TITANIFEROlJS M~'l'RRT~T.. ~
This invention relates to the removal of impurities from
naturally occurring and synthetic titaniferous materials.
The invention is ~articularly ~uited to the en~ncement of
titaniferous materials used in the ~roduction of titanium
metal and titanium dioxide pigments by means of indu~trial
chlorination systems.
15 Embo~;m~ntg of the pre~ent invention have the common features
of the use of caustic le~ch;ng and ~re~sure sulphuric acid
l~ch;ng for the upgrading of titaniferous materials, e.g.
titaniferous slags, derived from hard rock ilmenite~.
Additional steps may be employed as will be described below.
In industrial chlorination processes titanium dioxide bearing
feedstocks are fed with coke to chlorinators of various
designs (fluidised bed, shaft, molten salt), operated to a
~o~;~lm temperature in the range 700 - 1200C. The most
25 C~ 'n type of industrial chlorinator is of the fluidi~ed bed
de ign. Gaseous chlorine is passed through the titania and
carbon bearing charge, converting titanium dioxide to
titanium tetrachloride gas, which is then removed in the exit
gas stream and con~enced to liquid titanium tetrachloride for
further purification and processing.
The chlorination process as conducted in industrial
chlorinators is well suited to the conversion of pure
titanium dioxide feedstocks to titanium tetrachloride.
~owever, most other inputs (i.e. impurities in feedstocks)
cause difficulties which ~reatly complicate either the
chlorination process itself or the subsequent stages of
S~ lUl~SHEET ~R~e ~)
-
- 2 1 7 1 1 8 5 PCT/AUg4mOS28
W095/07366 ~
co~n~ation and purification and dis~osal of waste. The
attached table ~ro~ides an indication of the types of
problems encountered. In addition, each unit of inputs which
does not enter ~roducts contributes substantially to the
generation of wastes for treatment and disposal. Some inputs
(e.g. particular metal~, radioacti~es) result in waste
cla sifications which may require s~ecialist disposal in
monitored re~ositories.
Preferred inputs to chlorination are therefore hi~h ~rade
materials, with the mineral rutile (at 95-96% Tio2) the most
~uitable of ~re~ent feeds. Shortages of rutile ha~e led to
the de~elopment of other feed~tocks formed by upgrading
naturally occurring ilmenite (at 40-60% Tio2), such as
titaniferous slag (a~roximately 86% Tio2) and synthetic
rutile (variouQly 92-95% Tio2). The~e upgrading processes
ha~e had iron le~oval as a primary focus, but have extended
to removal of magnesium, mangane~e and alkali earth
im~urities, as well as ~ome aluminium.
~U~lllUl~ SHEET ~e
21 7 l l 85
PCT/AU9~/00528
WO 95/0736G
Blemental Chlorination Cond~n~ation Purification
Input
Fe, Mn C o n R u m e sSolid/liquid
chlorine, c h l o r i de 8
c o k e ,f o u
increasesductwork,
gas volumes make sludges
Alk:~l; lic Def luidise
a l k a l i fluid beds
e a r t h d u e t o
metals l i ~ u i d
chlorides,
c o n 8 ume
chlorine,
coke
Al ConsumesC a u 8 e g C a u g e s
chlorine, corrosion corrosion, makes
coke sludges
Si Ac.;l 1 Ates Can May reguire
i nencourage distillation
chlorinator, d u c t from product
r e d u c i n gb 1 o c k a g e .
c a m p a i g nC~n~n~es in
life. part with
Consumes t i t a n i u m
c o k e , tetrachloride
chlorine
V Must be L. ~ved,
by chemical
treatment and
distillation
Th, Ra AC cumul at e s
i n
chlorinator
brickwork,
radioac t ive;
c a u g e g
d i g p o 8 a 1
dif ficulties
In the prior art synthetic rutile has been formed from
titaniferous minerals, e.g. ilmenite, via various
techniques . According to the most commonl y al?~lied
technique, as variously operated in Western Australia, the
5 titaniferous mineral is reduced with coal or char in a
rotary kiln, at temperatures in excess of 1100C. In this
process the iron content of the mineral i8 gubgtantially
~U~ Ul~ SHEET (Rule 26)
W095/~7366 2 ~ 7 1 1 8~ ~CT1~94/0~528 ~
metallised. Sulphur additions are also made to convert
manganese impurities partially to sulphiaes. Following
reduction the metallised product is cooled, separated from
associated char, and then subjected to a~ueous aeration for
removal of virtually all cont~; n~ metallic iron as a
separable fine iron oxide. The titaniferous product of
separation is treated with 2-5% aqueous sulphuric acid for
dissolution of manganese and some residual iron. There is
no substan~ial chemical c~oval of alkali metals or
alkaline earths, aluminium, silicon, vanadium or
radionuclides in this process as disclosed or operated.
Further, iron and manganese removal is incomplete.
Recent disclosurec have provided a process which operates
reduction at lower temperature~ and provides for
hydrochloric acid l~ch; n~ after the aqueous aeration and
iron oxide separation step~. According to these disclosures
the proce~ is effective in ~o-ving iron, manganese,
alkali and alkaline earth impurities, a substantial
proportion of aluminium inputs and some ~anadium as well as
thorium. The process may be o~erated as a retrofit on
existing kiln based installations. However, the process is
ineffective in full vanadium removal and has little
chemical impact on silicon.
In another prior art invention relatively high de~rees of
~ - ~val of magnesium, man~anese, iron and aluminium have
been achieved. In one such proces~ ilmenite is first
therm~lly reduced to substantially com~lete reduction of
its ferric oxide content (i.e. without substantial
metallisation), norm~lly in a rotary kiln. The cooled,
reduced product is then leached under 35 psi pressure at
1~0-150C with excess 20% hydrochloric acid for remo~al of
iron, ma~nesium, aluminium and manganese. The leach liquors
are spray roasted for re~eneration of hydroqen chloride,
which is recirculated to the leachin~ ste~.
~U~Slllul~ SHEET ~e26)
-
2 1 7 1 1 8 5 PCT/AUs~/00~28
W095/07366
In other ~rocesse~ the ilmenite undergoes grain refinement
by therm~l oxidation followed by therr~l reduction (either
in a fluidised bed or a rotary kiln). The cooled, reduced
product is then subjected to atmospheric leAch;n~ with
exce~s 20% hydrochloric acid, for ~ e~G~al of the
deleterious impuritie~. Acid regeneration is also performed
by spray roa~ting in this ~rocess.
In all of the above mentioned hydrochloric acid leaching
based proces~es impurity removal i~ ~imilar. Vanadium,
aluminium and ~ilicon le a~al i8 not fully effective.
In yet another ~roces~ ilmenite i~ thermally reduced
(wil:hout metallisation) with carbon in a rotary kiln,
followed by cooling in a non-oxidising atmosphere. The
coo:Led, reduced ~roduct is le~che~ under 20 - 30 p~i gauge
~re~ure at 130C with 10 - 60% (typically 18 - 25%)
sul~huric acid, in the ~resence of a ~eed material which
ass:ists hydrolysis of dissolved titania, and consequently
ass:ists l~ch;ng of im~urities. Hydrochloric acid usage in
place of ~ulphuric acid ha~ been claimed for this process.
~nder such circumstances similar impurity removal to that
achieved with other hydrochloric acid based systems is to
be expected. Where ~ulphuric acid i8 used radioactivity
removal will not be com~lete.
A co~ly adopted method for upgradin~ of ilmenite to
higher grade productA is to smelt ilmenite at temperatures
in excess of 1500C with coke addition in an electric
furnace, producing a molten titaniferous slag (for casting
and cru~h; ng) and a pig iron product. Of the problem
impuritie~ only iron is removed in this manner, and then
only ;nco~letely as a result of compo~itional limitation~
of t:he proces~.
In another proces~ titaniferous ore i~ roa~ted with alkali
metal compounds, followed by leaching with a ~trong acid
SUB~ Ul~SHEET ~e26)
: : ~ 1 7 1 1 8 5 PCT/AU91/~0528
W095/07366 ~
other than sulphuric acid (Au~tralian Patent No. A~-B-
70976/87). According to this aisclo~ure substantial
removal of various impurities is achieved, with
~ub~Anti~7~ defined to mean greater than 10%. In the
context of the present invention such poor l~o~al of
impurities, especially of thorium and uranium, would not
re~resent an effective process. No ~pecific ~hase
structure after roasting is indicated for this process but
it is evident from analytical re~ults provided (where
product analyses, unlike feed analyses do not sum to 100%
and analyses for the alkali metal added are not given) that
there may have been significant retention of the additi~e
in the final product. ~nder the condition given it is
herein disclosed that it is to be expected that alkali
ferric titanate com~ounds which are not Am~n~hle to
subsequent acid l~ch;ng will form. The consequent
retention of alkali will render the final product
unsuitable as a feedstock for the chloride ~igment proces~.
In yet another ~rocess a titaniferous ore is treated by
alternate leaching with an agueous solution of alkali metal
com~ound and an aqueous solution of a non-sul~huric mineral
acid (~S Patent No. 5,085,837). The process is
specifically limited to ores and concentrates and does not
contemplate prior processing aimed at artificially altering
phase structures. Consequently the ~rocess requires the
applica~ion of excessive reagent and harsh processing
conditions to be even partially effective and i~ unlikely
to be economically im~lemented to produce a feedstock for
the chloride ~igment ~rocess.
A wide range of ~otential feedstocks is available for
upgrading to high titania content materials suited to
chlorination. Examples of primary titania ~ources which
cannot be satisfactorily upgraded by prior art processes
for the ~urposes of ~roduction of a material suited to
chlorination include hard rock (non detrital) ilmenites,
SUB~lllUl~SHEET ~e26)
W095/07366 ~ 2 1 7 1 1 a 5 PCT/AU94/00528
~iliceous leucoY~n~, many ~rimary (unweathered) ilmenites
and large anatase resources. Many such secondary sources
(e.g. titania bearing slags) also exist.
5 In particular, for titaniferous materials cont~;n;ng
J elevated levels of silica, alumina and ~gn~ia, such as
titaniferous slags derivea from hard rock ilmenite sources,
none of the previously aisclosed upgrading methods is
eff0ctive for the ~roduction of a feedstock for the
10 co_~ercial chloride pigment processing route. The
combination of silica which cannot be removed ~conomically
by the ~reviously identified techniques and alu_ina and
magnesia which together as~ist in the formation during
~h~r~- 1 ~roce~sing of ~seudobrookite - anosovite ty~e
15 ~hages which are not amenable to leachin~ with hydrochloric
acid under commercially realistic conditions limits the u e
of such materials to sul~hate ~igment process feedstocks.
Since the ~igment ~rocess expected to su~ly all growth in
pigment ~ n~ is the chloride ~rocess such a limitation is
20 a severe con~traint.
A lar~e ~ortion of the world~s identified titania reserves
i~ in the form of hard rock ilmenites.
25 Clearly there is a considerable incentive to discover
methods for u~grading of such titaniferou~ materials which
can economically ~roduce high grade products which are
suitable as feeastocks to the chloride pi~ment process.
30 The ~resent invention ~rovides a combination of processing
teps which may be incor~orated into more general ~rocesses
for the upgraaing of titaniferous materials, rendering such
proc~esses ap~licable to the treatment of a wider range of
feed$ and producin~ higher quality products than would
35 otherwise be achievable.
Accordingly, the ~resent invention ~roviaes a ~rocess for
SUB~ Ul~sHEET ~e ~)
W095/07366 - 2 1 7 ~ 1 8 5 PCT/AU9~/00528 ~
u~grading a titaniferou~ material by removal of impurities,
which proce~s involves alternately le~ch;n~ of the material
in a caustic leach and a pressure sul~huric acid leach.
In a particular embo~;m~nt the ~resent invention ensures
that caustic leAch; ng can be conducted economically and
effectively des~ite the need for the use of exces~ caustic
in the leach by circulation of caustic leach liquor~ after
~olid/liquid se~aration through a caustic regeneration step
using lime addition to ~reci~itate complex aluminosilicates
and regenerate caustic solution. The complex
aluminosilicate~ are then separated ~rom the regenerated
caustic solution which is recycled to the leach.
The treatment of titaniferous material~ cont~;n;ng both
all ; n~ and silica in such a manner has not previously been
disclo~ed, and it is herein revealed that only under
s~ecific operating conditions can such a ~roce~s be
operated without precipitation of com~lex aluminosilicates
in the cau~tic leach.
It has been surprisingly discovered that by limiting the
concentrations of ilica, alumina, titania and other
impuritie~ in caustic leach liquor, i.e. by leACh; ng at low
slurry densities and recirculating leach liquors through
caustic re~eneration, the complex aluminosilicates
otherwi3e formed in the caustic leach can frequently be
avoided.
It ha~ also been surprisingly discovered that complex
aluminosilicates formed in the caustic leach csn actually
be le~o-ved in the subsequent acid leach along with other
impurities. This is a ~articularly surprising outcome as
under most circum~tances silica in titaniferous materials
cannot be le~oved by acid le~ch;ng.
Consequently, in a further embodiment it is possible to
SUB~ u l ~. SBET (Rule 26)
. 2 1 7 l 1 ~ 5 PCT/AUs~/00~28
Woss/o7366
operate a simple process invol~ing a two stage treatment in
which complex aluminosilicates are formed in a first stage
and consumed by acid l~ch;ng in a second stage, wherein
silica remo~al is achieved in the acid l~ch;ng stage along
with the other benefits of acid l~h;nq in more general
upgrading.
In ~articular it is re~ealed that the ease of formation in
caustic leaching and ~o-val in acid l~ch;ng of complex
aluminosilicates depends on the caustic to silica ratio in
the leach liquor (which determines whether the
aluminosilicates are of the sodalite type or in another
form), with high caustic to silica ratios allowing greater
ease of removal. Thus, the circulation of caustic leach
liquors through a caustic leach and caustic regeneration by
lime (which keeps the caustic to silica ratio high)
folLowed by pressure sulphuric acid le~c~; n~ is under many
circumstance~ a most effective means of u~rading
titaniferous materials, especially titaniferous materials
deri~ed from hard rock ilmenite.
It has been discovered that the process of the in~ention
can ~-ove iron, magnesium, aluminium, silicon, calcium,
magnesium, manganese, phosphorus, chromium and ~anadium,
which impurities form an almost comprehenQi~e list of
im~urities in hard rock ilmenite sources of titania.
Additional ste~s may be incorporated in the process, as
desired. For example:
(1) The titaniferous material may be roasted in any
suitable de~ice and to any temperature under
reducinq or oxidising conditions prior to
le~rh; ng, Such roasting may be conducted in
order to ~nh~nce the response of the material to
the leachinq steps or to reduce the production of
sulphur dioxide in the leach by oxidation of any
SUB~ ul~-SBET ~e ~)
2 1 7 1 1 85
W095/07366 - PCT/AU9~/00528
tri~alent titania in the titaniferou~ material.
(2) Additi~es may be made to the titaniferous
material prior to such a roasting step in order
to ~nh~nce the response of the material to the
leAch;ng steps, or for any other purpose.
(3) The titaniferous material may be preground prior
to roasting or le~ch;ng in order to ~nh~nce
reaction rates or in ~reparation for
agglomeration steps which are improved by
generation of a broad particle ~ize distribution
in the material to be agglomerated.
15 (4) An agglomeration step via which additi~es are
incorporated into the titaniferous material prior
to roasting may be operated.
(5) Physical separation of material (e.g. maqnetic
se~aration of final product in order to
~electively e~e and recycle iron rich
material) for further upgrading.
(6) ~he final titaniferous ~roduct may be
agglomerated by any suitable technique to produce
a size consist which is suitable to the market
for synthetic rutile. After agglomeration the
product may be fired at temperatures sufficient
to ~roduce sintered bonds, thereby removing from
dusting losses in fluidised bed chlorinators.
(7) Irrespective of final product agglomeration the
final product may be calcined in order to remo~e
~olatile matter (e.g. water, sulphur dioxide and
sulphur trioxide).
(8) A caustic solution bleed or caustic solution
S~SlllUl~sHEET ~e26)
2 1 7 1 ~ ~ 5 PCT/AU94/00528
_ W095/07366
11
eva~oration step (for wash water removal) may be
operated.
(9) The sulphuric acid leach exit liquor may be
neutralised to produce solid sulphates and
hydroxides for dis~osal.
(10~ The sul~huric acid leach exit liquor may be
treated for regeneration of sul~huric acid from
the aqueous sulphate solutions formed in the
process.
(11) Other leach steps, filtration steps and w~qhing
steps may be incorporated into the process as
desired. For example, a hydrochloric acid leach
may; be conducted to assist in the ~oval of
trace levels of radioactivity. Pressure
filtration of the com~lex aluminosilicate
precipitated in caustic recovery may be operated
to assist solid/liquid se~aration.
(12) Flocculants and other aias may be used to assist
solid/li~uid separation.
ExamPles
The following examples describe a nnmher of laboratory
testa which serve to illustrate the t~hn;~ues described
herein.
Example 1
This exam~le i to ~rm~natrate the ineffectiveness of
trea~ments found to be effective for upgradin~ other
titaniferous materials on materials such as titaniferous
~lag~ produced from hard rock ilmenites.
Comme~cial titaniferous slag having the composition
indicated in Table 1 was subjected to oxidation roasting in
air at 750C for 30 minutes, followed by reduction roasting
SUB~lllUl~sHEET ~e ~)
W095/07366 2 ~ 7 1 1 8 5 PCT/AU9~100528 ~
12
in a 1:3 hydrogen to carbon dioxide (volumetric basis) gas
mixture at 680C for one hour. The cooled product of this
therm~l treatment cont~;ne~ no ferric iron and no trivalent
titania. The phase composition of the material was
indicated by X-ray diffraction as pseudobrookite.
The ~h~rm~l ly treated material was leArhe~ in refluxing 10%
caustic soda solution at 10% slurry density. After
filtration and wA~hing the solid residue had a composition
as indicated in Table 2.
It is clear that caustic leach had no appreciable effect on
the silica or alumina contents of the material.
The re idue of the caustic leach was subjected to a leach
with refluxing 20% hydrochloric acid at 30% slurry density
for 6 hours. After filtration and w~h;ng the solid
residue had the com~osition which is also indicated in
Table 2.
Clearly a roast/leach process using 10% caustic soda at 10%
slurry density and 20% hydrochloric acid at 30% slurry
density as leAch~nts is almost totally ineffective in
upgrading the slag.
Exam~le 2
The treatment indicated in ~xample 1 was re~eated with the
exception that the caustic leach was con~cted under
pressure at 165C.
The compositions of the caustic and acid leached products
are indicated in Table 3. It i clear that the caustic
leach had no appreciable effect on the silica or alumina
contents of the material. The acid leach, however, despite
being largely ineffective in producing an upgrade which
might be suitable for the chloride pigment proces~ did have
a substantial effect on the silica and alumina contents.
~U~S'lll'U'l'~. SHEET (Rule 26)
~ W095/07366 = ~ 2 ~ 7 1 ~ 8 5 PCT/AUs~/00528
13
There was no such effect on a sample of slag submitted
directly to hydrochloric acid leaching.
Clearly the ~ressure caustic leach had altered the state of
the silica to allow its subsequent ~o~dl in hydrochloric
acid le~chi ng but had not resulted in direct removal.
Investigations revealed the proauction of a complex
aluminosilicate precipitate in the caustic leach. The
caustic leach had been conducted under conditions in which
silica could be leAche~ but was not soluble.
The re~ults of thi~ example combined with the result~ of
subsequent examples in which effective caustic l~A~h;n~ is
demonstrated illustrate the dep~n~ence of the removal of
~ilica and alumina in caustic l~ch;ng on the leach
conditions.
Example 3
A sample of the slag whose composition is indicated in
Table 1 was mixed with 2% borax, formed into pellet~ and
~ubjected to reduction roasting in a 19:1 hydrogen to
carbon dioxide (volumetric basis) gas mixture at 1000C for
2 hours. The phase composition of the cooled product of
this thermal treatment wa3 indicated by X-ray diffraction
a~ ~seudobrookite.
A sample of the thermally treated material was l~che~ in
refluxing 10% caustic soda solution at 5% slurry density.
After filtration and w~h;n~ the solid residue had a
composition as indicated in Table 4. It is clear that the
caustic leach was highly effective in the le~o~al of
~ilica, despite the much poorer performance of a leach
conducted at 10% slurry den~ity in Example 1, in which
complex aluminosilicates were formed.
The residue of the caustic leach was ~ubjected to a
pressure leach at 150C with 20% sulphuric acid at 5%
S~SlllUlhSHEET ~e26)
W095/07366 - 2 ~ 7 1 I 8 5 PCT/AU9~mOS28 ~
14
slurry density for 6 hours. After filtration and wA~hing
the ~olid residue had the composition which i~ al~o
indicated in Table 4.
Clearly the combined effects of a low slurry density
caustic leach and a subsequent pressure sulphuric acid
leach (which is ca~able of decomposing ~seudobrookite) were
to substantially upgrade the slag to a very high grade
product which is suitable in composition a~ a chloride
pi~ment proce~ feedstock.
The leach liquor from the above caustic leach was ~re~erved
and after analysis was treated with microni~ed lime at the
weight ratio of 1.3 units of lime per unit of dissolved
silica. The resulting complex aluminosilicate ~recipitate
and any exce3s lime were removed by filtration and the
"re~enerated~l caustic solution was preser~ed for reuse in
leaching.
A further sample of the th~ -lly treated material was
l~ch~ with the regenerated cau~tic solution under the
same conditions as indicated above. There was no
difference of any consequence between the re~ults of the
leach with fresh caustic and the results of the leach with
re~enerated caustic.
Example 4
Thi3 example i~ to demonstrate the ineffecti~eness of acid
leaching alone in the e~val o~ silica from titaniferous
materials such as titaniferous slags produced from hard
rock ilmenite~.
Co cercial titaniferous slag having the composition shown
in Table 1 was subiected to roasting for two hours in an
atmosphere of 1:19 (volumetric basi~) of hydrogen to carbon
dioxide at 1000C. After cooling in the roaating
atmos~here the roasted slag wa~ pressure leAch~ at 135C
SU~lllUl~SHEET ~e26)
~ W095/07366 2 1 7 1 1 8~ PCT/AUs~/00528
in 20% sul~huric acid at 25% w/w slurry density for six
hours.
- The composition of the leach resiaue is given in Table 5.
Such direct acid leach treatment of a roasted titaniferous
material may be antici~ated to result in little im~rovement
of ~roduct quality by l~ch;ng~ and no removal of SiO2.
Example 5
A nample of slag to which no addition of additive had been
made and which was not ~ubjected to any thermal treatment
was treated by the same leaching steps as indicated in
Example 3.
The composition of the final ~roduct was as recorded in
Table 6. Substantial 1.- ~,-val of impuritie~ have been
achieved without thermal treatment.
S~SlllUl~ SHEET ~e26)
2 1 7 1 1 8 5 PCT/AU9~/00528
W095/07366 -
16
Table 1: Com~o~ition of Titaniferou~ Sla~
~sed In Example 1 - 4
wt~
Tioa 78.9
FeO 8.94
~gO 4.73
MnO 0.25
Cr2O3 0.16
V2Os 0.56
Al2O3 3.14
SiO2 2.71
Zr2 0.05
CaO 0.42
Table 2: Composition of Products in Exam~le 1
wt% Caustic T~eAch Acid T~e~ch
Tio2 78.6 80.8
FeO 9.22 7.4
MgO 4.71 4.69
MhO 0.24 0.23
Cr2O3 0.16 0.16
V2O5 0.59 0 59
Al2O3 3 09 3.06
SiO2 2.94 2.86
ZrO2 0.05 0.04
CaO 0.37 0.16
SUB~lllul~. SHEET (l~ule Z6)
W095l07366 2 1 7 1 ~ 8 5 PCT/AU9~/00528
17
Tab:Le 3: Com~osition of Proaucts in Example 2
wt% Cau~tic Leach Acia T-e~Ch
Tio2 78.4 82.7
FeO 9.13 7.66
MgO 4.76 4.81
MnO 0.25 0.23
Cr2O3 0.16 0.16
V25 0.58 0.60
A12O3 3.08 2.73
sio2 3.13 0.96
ZrO2 0.05 0.04
CaO 0.40 0.13
Table 4: Compo~ition of Proaucts in Example 3
wt% caustic T-~ch Acia T-~Ch
Tio2 81.3 97.9
FeO 9.56 0.89
~gO 4.96 0.44
MnO 0.27 0.02
Cr2O3 0.20 0.12
V2Os 0.57 0.12
A12O3 1.75 0.23
SiO2 0.73 0.09
zrO2 0.05 0.06
CaO 0.45 0.003
SUBST~I~ESHEET ~e ~)
W095/07366 ~ 2 1 7 1 1 8 5 PCT/AU9l/00528 ~
Table 5: Composition of Product in Exam~le 4
wt% Acid Leach
Tio2 84.93
FeO 6.09
MgO 2.92
MnO 0.16
Cr2O3 0.16
V2O5 0.60
Al2O3 1.33
/ sio2 3.15
Zr2 0.06
CaO 0.03
Table 6: Composition of Product in Example 5.
wt% Acid T-e~ch
Tio2 92.1
FeO 2.98
~ 1.21
MnO 0.08
Cr2O3 0.16
V2O5 0.18
Al23 0.60
sio2 0.71
Zr2 0.06
Cao o-003
S~ l u l ~. S~ET (Rule 26)
