U.S. patent application number 09/819095 was filed with the patent office on 2002-08-08 for upgrading titaniferous materials.
Invention is credited to Hollitt, Michael John, McClelland, Ross Alexander, Tuffley, John Roger.
Application Number | 20020104406 09/819095 |
Document ID | / |
Family ID | 25644310 |
Filed Date | 2002-08-08 |
United States Patent
Application |
20020104406 |
Kind Code |
A1 |
Hollitt, Michael John ; et
al. |
August 8, 2002 |
Upgrading titaniferous materials
Abstract
The application discloses a process for upgrading a titaniferous
material by removal of impurities contained in the material
especially radionuclides. The process involves heating the
titaniferous material to a temperature of less than 1300.degree. C.
to form a solid titaniferous phase and a liquid oxide or glassy
phase in the presence of a material that promotes the formations of
such phases, cooling the product at a rate that maintains the
glassy phase in an amorphous state and leaching the solidified
material with an acid or an alkali to remove the impurities.
Materials that promote the formation of the desired phases include
compounds of alkali metals and boron. Examples include borax,
caustic soda, soda ash and silica.
Inventors: |
Hollitt, Michael John; (Box
Hill North, AU) ; McClelland, Ross Alexander;
(MaryKnoll, AU) ; Tuffley, John Roger; (Burnside,
AU) |
Correspondence
Address: |
Dennison Meserole Pollack & Scheiner
1745 Jefferson Davis Highway Suite 612
Arlington
VA
22202
US
|
Family ID: |
25644310 |
Appl. No.: |
09/819095 |
Filed: |
April 26, 2001 |
Current U.S.
Class: |
75/420 |
Current CPC
Class: |
C22B 34/1213 20130101;
Y02P 10/20 20151101; C22B 34/1209 20130101; C22B 34/1204 20130101;
C22B 3/10 20130101; C22B 1/243 20130101; C22B 1/02 20130101 |
Class at
Publication: |
75/420 |
International
Class: |
C22B 034/12 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 14, 1992 |
AU |
PL 4105 |
Feb 10, 1993 |
AU |
PL 7193 |
Claims
1. A process for upgrading a titaniferous material by removal of
impurities which process includes the steps of: (i) heating a
titaniferous material to a temperature of less than 1300.degree. C.
to produce a solid titaniferous phase and a liquid oxide or glassy
phase in the presence of sufficient of compounds which encourage
the formation of the liquid oxide or glassy phase; (ii) cooling the
product of step (i) to form a solidified material comprising the
titaniferous phase and an impurity bearing phase at a rate
sufficient to ensure the susceptibility of the impurity bearing
phase to leaching in either an acid or alkaline leachant; and (iii)
leaching the solidified material with an acidic or alkaline
leachant to leach at least a portion of the impurities.
2. A process for upgrading a titaniferous material according to
claim 1 wherein the compounds which encourage the formation of the
liquid oxide or glassy phase at a temperature below 1300.degree. C.
are compounds of sodium, potassium, lithium, phosphorus silicon or
boron.
3. A process for upgrading a titaniferous mineral according to
claim 2, wherein the compound of sodium is caustic soda.
4. A process for upgrading a titaniferous mineral according to
claim 2, wherein the compound of sodium is sodium carbonate.
5. A process for upgrading a titaniferous mineral according to
claim 2, wherein the compounds include borax.
6. A process for upgrading a titaniferous mineral according to
claim 2, wherein the compounds comprise a mixture of soda ash and
borax.
7. A process according to claim 6, wherein the titaniferous
material is heated to a maximum temperature of 1000.degree. C. for
a period which avoids substantial reduction to metal of contained
iron oxides.
8. A process according to claim 7, wherein the solidified material
is leached with water.
9. A process according to claim 7, wherein the solidified material
is leached with a recycled solution of leach liquor containing
sodium silicate and borax to form a leachate and a residue.
10. A process according to claim 9, wherein the leachate is
separated from the residue and the residue is leached with
hydrochloric acid having an acid strength in a range from 1 to 20%
hydrochloric acid.
11. A process according to claim 1 wherein the compounds include
compounds which extend the effect of other compounds.
12. A process according to claim 11 wherein a compound which
extends the effect of other compounds is borax.
13. A process according to claim 1 wherein sufficient compounds are
present to avoid the formation of titanate phases that are not
amenable to subsequent leaching.
14. A process according to claim 1 wherein the solidified material
is leached under mild conditions.
15. A process according to claim 14 wherein the solidified material
is leached at atmospheric pressure.
16. An upgraded titaniferous material produced by the process of
any one of claims 1 to 15.
Description
[0001] This invention relates to the removal of impurities from
naturally occurring and synthetic titaniferous materials. The
invention is particularly suited to the enhancement of titaniferous
materials used in the production of titanium metal and titanium
dioxide pigments by means of industrial chlorination systems.
[0002] Embodiments of the present invention have the common feature
of roasting of titaniferous materials in the presence of additives
and at temperatures which encourage the formation of a liquid oxide
or glassy phase, followed at some stage by cooling and aqueous
leaching as steps in an integrated process. Additional steps may be
employed as will be described below.
[0003] 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 maximum
temperature in the range 700-1200C. The most common type of
industrial chlorinator is of the fluidised bed design. 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 condensed to liquid
titanium tetrachloride for further purification and processing.
[0004] The chlorination process as conducted in industrial
chlorinators is well suited to the conversion of pure titanium
dioxide feedstocks to titanium tetrachloride. However, most other
inputs (i.e. impurities in feedstocks) cause difficulties which
greatly complicate either the chlorination process itself or the
subsequent stages of condensation and purification and disposal of
waste. The attached table provides an indication of the types of
problems encountered. In addition, each unit of inputs which does
not enter products contributes substantially to the generation of
wastes for treatment and disposal. Some inputs (e.g. particular
metals, radioactives) result in waste classifications which may
require specialist disposal in monitored repositories.
[0005] Preferred inputs to chlorination are therefore high grade
materials, with the mineral rutile (at 95-96% TiO.sub.2) the most
suitable of present feeds. Shortages of rutile have led to the
development of other feedstocks formed by upgrading naturally
occurring ilmenite (at 40-60% TiO.sub.2), such as titaniferous slag
(approximately 86% TiO.sub.2) and synthetic rutile (variously
92-95% TiO.sub.2). These upgrading processes have had iron removal
as a primary focus, but have extended to removal of magnesium,
manganese and alkali earth impurities, as well as some
aluminium.
1 Elemental Input Chlorination Condensation Purification Fe, Mn
Consumes Solid/liquid chlorine, chlorides coke, foul increases
ductwork, gas volumes make sludges Alkali & Defluidise alkali
fluid beds earth due to metals liquid chlorides, consume chlorine,
coke Al Consumes Causes Causes chlorine, corrosion corrosion, coke
makes sludges Si Accumulates Can May require in encourage
distillation chlorinator, duct from product reducing blockage.
campaign Condenses in life. part with Consumes titanium coke,
tetrachloride chlorine V Must be removed, by chemical treatment and
distillation Th, Ra Accumulates in chlorinator brickwork,
radioactive; causes disposal difficulties
[0006] In the prior art synthetic rutile has been formed from
titaniferous minerals, e.g. ilmenite, via various techniques.
According to the most commonly applied technique, as variously
operated in Western Australia, the titaniferous mineral is reduced
with coal or char in a rotary kiln, at temperatures in excess of
1100 C. In this process the iron content of the mineral is
substantially metallised. Sulphur additions are also made to
convert manganese impurities partially to sulphides. Following
reduction the metallised product is cooled, separated from
associated char, and then subjected to aqueous aeration for removal
of virtually all contained 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 substantial chemical removal 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.
[0007] Recent disclosures have provided a process which operates
reduction at lower temperatures and provides for hydrochloric acid
leaching after the aqueous aeration and iron oxide separation
steps. According to these disclosures the process is effective in
removing iron, manganese, alkali and alkaline earth impurities, a
substantial proportion of aluminium inputs and some vanadium as
well as thorium. The process may be operated as a retrofit on
existing kiln based installations. However, the process is
ineffective in full vanadium removal and has little chemical impact
on silicon.
[0008] In another prior art invention relatively high degrees of
removal of magnesium, manganese, iron and aluminium have been
achieved. In one such process ilmenite is first thermally reduced
to substantially complete reduction of its ferric oxide content
(i.e. without substantial metallisation), normally in a rotary
kiln. The cooled, reduced product is then leached under 35 psi
pressure at 140-150 C with excess 20% hydrochloric acid for removal
of iron, magnesium, aluminium and manganese. The leach liquors are
spray roasted for regeneration of hydrogen chloride, which is
recirculated to the leaching step.
[0009] In other processes the ilmenite undergoes grain refinement
by thermal oxidation followed by thermal reduction (either in a
fluidised bed or a rotary kiln). The cooled, reduced product is
then subjected to atmospheric leaching with excess 20% hydrochloric
acid, for removal of the deleterious impurities. Acid regeneration
is also performed by spray roasting in this process.
[0010] In all of the above mentioned hydrochloric acid leaching
based processes impurity removal is similar. Vanadium, aluminium
and silicon removal is not fully effective.
[0011] In yet another process ilmenite is thermally reduced
(without metallisation) with carbon in a rotary kiln, followed by
cooling in a non-oxidising atmosphere. The cooled, reduced product
is leached under 20-30 psi gauge pressure at 130.degree. C. with
10-60% (typically 18-25%) sulphuric acid, in the presence of a seed
material which assists hydrolysis of dissolved titania, and
consequently assists leaching of impurities. Hydrochloric acid
usage in place of sulphuric acid has been claimed for this process.
Under such circumstances similar impurity removal to that achieved
with other hydrochloric acid based systems is to be expected. Where
sulphuric acid is used radioactivity removal will not be
complete.
[0012] A commonly adopted method for upgrading of ilmenite to
higher grade products is to smelt ilmenite at temperatures in
excess of 1500.degree. C. with coke addition in an electric
furnace, producing a molten titaniferous slag (for casting and
crushing) and a pig iron product. Of the problem impurities only
iron is removed in this manner, and then only incompletely as a
result of compositional limitations of the process.
[0013] In another process titaniferous ore is roasted with alkali
metal compounds, followed by leaching with a strong acid other than
sulphuric acid (Australian Patent No. AU-B-70976/87). According to
this disclosure substantial removal of various impurities is
achieved, with "substantial" defined to mean greater than 10%. In
the context of the present invention such poor removal of
impurities, especially of thorium and uranium, would not represent
an effective process. No specific phase structure after roasting is
indicated for this process but it is evident from analytical
results 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
additive in the final product. Under the conditions given it is
herein disclosed that it is to be expected that alkali ferric
titanate compounds which are not amenable to subsequent acid
leaching will form. The consequent retention of alkali will render
the final product unsuitable as a feedstock for the chloride
pigment process.
[0014] In yet another process a titaniferous ore is treated by
alternate leaching with an aqueous solution of alkali metal
compound and an aqueous solution of a mineral acid (U.S. Pat. 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 process
requires the application of excessive reagent and harsh processing
conditions to be even partially effective and is unlikely to be
economically implemented to produce a feedstock for the chloride
pigment process.
[0015] A wide range of potential feedstocks is available for
upgrading to high titania content materials suited to chlorination.
Examples of primary titania sources which cannot be satisfactorily
upgraded by prior art processes for the purposes of production of a
material suited to chlorination include hard rock (non detrital)
ilmenites, siliceous leucoxenes, many primary (unweathered)
ilmenites and large anatase resources. Many such secondary sources
(e.g. titania bearing slags) also exist.
[0016] Clearly there is a considerable incentive to discover
methods for upgrading of titaniferous materials which can
economically produce high grade products almost irrespectively of
the nature of the impurities in the feed.
[0017] The present invention provides a combination of processing
steps which may be incorporated into more general processes for the
upgrading of titaniferous materials, rendering such processes
applicable to the treatment of a wider range of feeds and producing
higher quality products than would otherwise be achievable.
[0018] Accordingly, the present invention provides a process for
upgrading a titaniferous material by removal of impurities which
process includes the steps of:
[0019] (i) heating a titaniferous material to a temperature less
than 1300.degree. C. to produce a solid titaniferous phase and a
liquid oxide or glassy phase in the presence of sufficient of
compounds which encourage the formation of the liquid oxide or
glassy phase;
[0020] (ii) cooling the product of step (i) to form a solidified
material comprising the titaniferous phase and an impurity bearing
phase at a rate sufficient to ensure the susceptibility of the
impurity bearing phase to leaching in either an acid or alkaline
leachant; and
[0021] (iii) leaching the solidified material in an acidic or
alkaline leachant to leach at least a portion of the
impurities.
[0022] In order to ensure the formation of the solid titaniferous
phase and the liquid oxide or glassy phase during the heating step
it will normally be necessary to add to the titaniferous material,
prior to the heating step, sufficient of a compound that encourages
the formation of the liquid oxide or glassy phase. However, in some
cases it will not be necessary since the titaniferous material
itself may contain sufficient of such a compound.
[0023] It has been discovered that the process of the invention can
remove iron, magnesium and other alkaline earths, alkalis,
manganese, silica, phosphorus, alumina, vanadium, rare earths,
thorium and other radioactive elements, which impurities form an
almost comprehensive list of impurities in titaniferous mineral
sources. From most materials a product purity of greater than 96%
TiO.sub.2 can be obtained.
[0024] Compounds added to the titaniferous material may be mixed
therewith by any means ranging from direct mixing of additives
prior to charging to thermal treatment to more complex feed
preparations such as the formation of agglomerates or nodules of
mixed products, to briquette production from feeds and additives.
Many additives will be effective. In particular it is herein
disclosed that sodium, potassium, lithium, phosphorus, silicon and
boron compounds and minerals (e.g. borax, trona and other alkali
metal carbonates, spodumene, caustic soda) will be effective.
Additives may be incorporated individually or in combination with
other additives.
[0025] It is further disclosed herein that the formation of a
glassy phase by addition of alkali compounds can be achieved
without the formation of alkali titanate phases, reduced alkali
titanate phases (e.g. NaTiO.sub.2-compounds and solid solutions) or
alkali ferric titanate phases (e.g. Na(Fe, Al)O.sub.2--TiO.sub.2
phases known as "bronzes") in roasting. Where such titanate is
phases form their stability with respect to subsequent leaching
steps is such that the final product quality is adversely affected.
The incorporation of sufficient quantities of further additives
(e.g. boron or phosphorus compounds) which substantially reduce
alkali oxide chemical activity can have the effect of eliminating
these phases.
[0026] Under many circumstances it will be beneficial to
incorporate multiple additives into the material to be treated by
thermal processing. For example, it is herein disclosed that the
simultaneous presence of silica, anhydrous borax and sodium oxide
in 1000.degree. C. thermally processed material in weight ratios of
about 7:1:1 ensures the preferential formation of a glassy phase
over other phases containing silica or soda. In this formulation
the required borax addition is only just over 10% of the addition
which would be required for an equivalent amount of glassy phase
where other additives do not act as extenders. Since borax is by
far the most expensive additive of the three additives in this case
optimum economics are achieved by the use of the extenders.
[0027] Thermal processing may be carried out in any suitable
device. The production of liquid phases would recommend rotary or
grate kilning, but shaft furnaces may also be used and it has been
found that fluidised beds can be used under some circumstances. Any
gaseous atmosphere conditions may be used, from fully oxidising to
strongly reducing. The thermal processing atmosphere should be
chosen to most suit other steps in integrated processing. Reducing
conditions may be achieved where desired by either the use of a sub
stoichiometric firing flame or the addition of coal, char or coke
with the thermal processing charge.
[0028] Thermal processing residence time at temperature will depend
on the nature of the additives and the feed, as well as the
operating temperature. Residence times of from 5 minutes to five
hours have been effective, allowing thermal processing residence
times to be set to most suit other requirements in integrated
processing.
[0029] The level of additive used and the conditions applied in
thermal processing should be such that glassy phase formation does
not exceed the limitations set by materials handling constraints in
the thermal processing step. For example, where glassy phase
formation exceeds about 15% by volume of the roasted material it
must be anticipated that accretion and bed fusion problems will
occur.
[0030] Cooling of the thermally treated material should be
conducted in such a manner as to limit the reversion of the glassy
phase to crystalline phases, i.e. should be at a sufficient rate to
a temperature at which the liquid glass solidifies as to ensure the
formation of at least a portion of solid glass rather than complete
formation of crystalline products.
[0031] Further, cooling should be conducted under an environment
appropriate to the conditions of thermal treatment (i.e. reduction
processing will require cooling in an oxygen free environment).
[0032] The aqueous leaching step need not necessarily follow
directly after the presently disclosed thermal processing step. For
example if the thermal processing step is conducted under oxidising
conditions it may be optionally followed by a reduction step prior
to aqueous leaching. Further, crushing/grinding of the thermally
processed material to enhance subsequent leach performance may be
undertaken.
[0033] The conditions necessary to conduct effective leaching will
depend on the nature of the original feed and the additives. For
example, addition of soda ash and borax to siliceous leucoxene in
accordance with the present disclosure will result in a product
which can be leached in sodium silicate solution formed directly
from the thermally treated material; the active leachant in this
case is simply water. In other cases up to 100 gpL caustic soda
solution or acid will be an effective leachant. Leaching will
generally benefit substantially by use of high temperature (e.g.
80.degree. C. or above), although it has not been necessary to use
pressure leaching to achieve effective conditions. Nevertheless it
is presently disclosed that pressure leaching can be effectively
and successfully applied. Lower temperatures can also be used,
although with penalties in process kinetics.
[0034] Leaching may be conducted in any circuit configuration,
including batch single or multiple stage leaching, continuous
cocurrent multistage leaching, or continuous countercurrent
multistage leaching. For most circumstances two stage cocurrent
leaching will be most beneficial. Average residence time may vary
from 30 minutes to 10 hours, depending on process conditions. Any
leach vessel capable of providing adequate shear may be used.
Simple stirred tank vessels are applicable.
[0035] At the conclusion of leaching the leach liquor may be
separated from the mineral by any suitable means, including
thickening, filtration and washing. The mineral product may then
pass on to other steps in an integrated process. For example, a
further acid leach may follow the disclosed leaching step,
particularly where the titaniferous feed has a content of alkalis
or alkaline earths.
[0036] Other processing steps may be added as necessary or desired.
For example, reagent regeneration (e.g. caustic regeneration,
hydrochloric acid regeneration, sulphuric acid regeneration) can be
used with the process in order to improve process effectiveness or
economics. Similarly, a physical separation step may be employed at
any stage (e.g. a final magnetic separation to remove grains
containing iron, such as chromite).
EXAMPLES
Example 1
[0037] Sodium carbonate addition, corresponding to 4.25% Na.sub.2O
by weight, was made to a titania concentrate whose composition is
given in Table 1. The mixture was homogenised and pelletised, and
the pellets were heated in air to 1000.degree. C. for 4 hours. The
thus roasted pellets were quenched in liquid nitrogen and then
crushed to pass a screen of 200 microns aperture. The crushed
roasted pellets were subjected to leaching under reflux with 40 wt
% sodium silicate solution (SiO.sub.2:Na.sub.2O=2,4:1 by weight) at
4% slurry density. (Sodium silicate solution was used to simulate
leaching using water as leachant under conditions where the leach
liquors are recycled to leaching after solid/liquid
separation).
[0038] Solid/liquid separation was effected by centrifuging, after
which the leach residue was washed and calcined at 1000.degree. C.
for analysis. The analysis of the calcined product is also given in
Table 1.
[0039] The original concentrate was known to contain silica
primarily as quartz inclusions in titanate grains. X-ray
diffraction analysis after roasting indicated extinction of all
crystalline phases containing silica. A glassy phase containing 16%
Na.sub.2O, 46% SiO.sub.2, 9% Al.sub.2O.sub.3, 26% TiO.sub.2 and 3%
Fe.sub.2O.sub.3 was identified in the roasted material by electron
microscopy. Sodium titanates and sodium iron titanium bronze were
also identified (along with rutile) by these techniques, indicating
that conditions were not optimised.
[0040] Nevertheless, highly effective concentrate upgrading has
been achieved even where the benefits of subsequent acid leaching
have not been pursued, illustrating the benefits of the formation
of the glassy phase. Substantial removal of silica, alumina and
vanadium was achieved.
Example 2
[0041] This example illustrates the optimisation of additives for
both process effectiveness and most economic formulation.
[0042] In this example titania concentrates of the composition
given in Table 2 were used as titaniferous material for treatment.
Early work attempting to produce glassy phase with this material by
addition of sodium carbonate prior to roasting indicated that
glassy phase could easily be produced, but over a wide range of
conditions reduced sodium titanate or sodium iron titanate bronze
formation which resulted in sodium retention after leaching could
not be easily avoided.
[0043] Complete and partial replacement of sodium carbonate by
borax was tested.
[0044] Two batches of band pressed pellets were prepared as
follows. A 100 g sample of the concentrates (previously ground to
passing a screen aperture of 30 microns) was blended in each case
with 1.1% of the appropriate additive or additive mixture and the
resulting blends were pressed into pellets. The first batch was
prepared with 1.1 wt % of anhydrous borax addition while the second
batch was prepared with addition of 1.1 wt % of 1:1
Na.sub.2B.sub.4O.sub.7:Na.sub.2O.
[0045] Each batch of pellets was roasted for two hours in a 7:1
H.sub.2/CO.sub.2 atmosphere at 1000.degree. C. and then removed to
cool quickly in the same atmosphere. The roasted pellets were
ground to pass a screen aperture of 75 microns for subsequent
leaching. Ground roasted pellets were caustic leached under reflux
conditions for 6 hours in a 10% NaOH solution at 6.7% solids
density. Solid/liquid separation was effected by filtration, and
the caustic leached products were washed and dried in preparation
for subsequent acid leaching.
[0046] The caustic leached residues were acid leached in 15% HCl
for 4 hours under reflux, then similarly filtered, washed and
dried.
[0047] In each case samples of the concentrate and roasted material
were submitted for X-ray diffraction analysis. While quartz and
various ilmenite, anatase and rutile related phases were identified
in the concentrates the only crystalline phases identified in the
roasted product were rutile and ilmenite. All quartz had entered a
glassy phase, and no titanate phases which would reduce leach
effectiveness were identified.
[0048] Analyses of the caustic and acid leach residues in each
case, illustrating the effectiveness of the process where optimum
conditions are applied, are provided in Table 3.
Example 3
[0049] The same pellet formulations as indicated in Example 2 were
made up in 350 kg batches in an agglomeration plant and roasted at
30 kg/hr feed rate with 15% brown coal char addition to a final
temperature of 1000.degree. C. in a small (0.5 m diameter) rotary
kiln. Residence time above 900.degree. C. was approximately 10
minutes. There were no problems with accretions or bed fusion, and
after separation from residual char the products had exactly the
same properties as the roasted products of Example 2.
Example 4
[0050] A commercial titania slag product having the composition
indicated in Table 4 was processed as for the processing conditions
indicated in Example 2, but with 2 wt % anhydrous borax addition in
place of the other additives. The caustic leach was conducted at
165.degree. C. under pressure, and a pressure leach with 20%
sulphuric acid conducted at 135.degree. C. was used in place of the
hydrochloric acid leach. The final residue was calcined at
900.degree. C. for one hour. The products of this treatment are
indicated in Table 4.
Example 5
[0051] This example when compared with examples 1 and 2 illustrates
the advantages of the formation of a glassy phase.
[0052] Concentrates having the composition indicated in Table 1
were subjected leaching under atmospheric reflux conditions with
excess 20% HCl. After separation of the residue from the liquor
followed by washing and drying of the residue its composition was
as given in Table 5. Clearly there was ineffective removal of
virtually all impurities of interest by comparison with the other
examples provided herein.
2TABLE 1 Concentrates and Product from Example 1 wt % Concentrate
Product TiO.sub.2 85.8 94.9 Fe.sub.2O.sub.3 2.25 1.91
Al.sub.2O.sub.3 1.08 0.63 SiO.sub.2 7.62 0.74 Nb.sub.2O.sub.5 0.30
0.31 V.sub.2O.sub.5 0.235 0.02 Na.sub.2O 0.0 1.10
[0053]
3TABLE 2 Composition of Concentrates Used in Examples 2 and 3 wt %
TiO.sub.2 63.6 Fe.sub.2O.sub.3 28.6 SiO2 3.53 Al.sub.2O.sub.3 0.80
MgO 0.87 CaO 0.02 Cr.sub.2O.sub.3 0.55 MnO 1.11 V.sub.2O.sub.5 0.22
ZrO.sub.2 0.26 P.sub.2O.sub.5 0.04 U.sub.3O.sub.8 0.002 ThO.sub.2
0.01
[0054]
4TABLE 3 Compositions of Leach Products from Example 2 1.1%
Na.sub.2B.sub.4O.sub.7 1.1% 1:1 Na.sub.2B.sub.4O.sub.7:Na.sub.2O
addition addition Caustic Caustic Leach Acid Leach Leach Acid Leach
wt % Residue Residue Residue Residue TiO.sub.2 66.9 94.3 67.3 94.9
Fe.sub.2O.sub.3 27.1 30.2 30.6 2.04 SiO.sub.2 1.12 0.99 0.55 0.86
Al.sub.2O.sub.3 0.22 0.17 0.14 0.15 MgO 0.97 0.08 0.90 0.09 CaO
0.05 0.001 0.03 0.001 Cr.sub.2O.sub.3 0.68 0.69 0.70 0.67 MnO 1.15
0.06 1.19 0.06 V.sub.2O.sub.5 0.22 0.15 0.23 0.13 ZrO.sub.2 0.27
0.37 0.28 0.38 Na.sub.2O 0.05 0.02 0.15 0.03 P.sub.2O.sub.5 0.02
0.02 0.01 0.02 U.sub.3O.sub.8 0.002 0.002 0.002 0.002 ThO.sub.2
0.01 0.003 0.01 0.004
[0055]
5TABLE 4 Feed and Product in Example 4 Commercial Roast/Leach wt %
Slag Product TiO.sub.2 79.7 97.2 FeO 9.24 0.85 SiO.sub.2 3.11 0.09
Al.sub.2O.sub.3 3.23 0.38 MgO 4.81 0.43 CaO 0.41 0.002
Cr.sub.2O.sub.3 0.16 0.12 MnO 0.25 0.02 V.sub.2O.sub.5 0.57 0.12
ZrO.sub.2 0.046 0.06 P.sub.2O.sub.5 0.002 0.004 U.sub.3O.sub.8
0.0005 n.d. ThO.sub.2 0.0006 n.d. n.d. = not determined
[0056]
6TABLE 5 Results of Processing as described in Example 5 wt % Leach
Product TiO.sub.2 88.6 Fe.sub.2O.sub.3 0.98 SiO.sub.2 7.54
Al.sub.2O.sub.3 0.65 V.sub.2O.sub.5 0.198 U.sub.3O.sub.8 0.0054
ThO.sub.2 0.0094
* * * * *