Note: Descriptions are shown in the official language in which they were submitted.
~0~38ZS
The process basically con~i~ts of the removal of the
impuritie~ contained in titanium mineral~ by aoid leaching after
piro-metallurgical treatment which proceGses the ore and xenders
the impurities in que~tion easier to remove, by either permitting
closer contact between them and the leaching acid or by tran~form-
ing them into more soluble product~.
The increasing dearth of high content titanium ores
has called for intensive prospecting on a worldwide scale with
a view to obtaining from poor ores concentrate3 with contents
of titanium dioxide (~iO2) higher than 90%, for ~upplying the
consumer markets.
~ here are a number of patents in existence today
aimed at the enrichment of titanium mineral~ 80 as to obtain
high content concentrates.
In the whole of the known proce~ses the raw material
used is ilmenite, which i9 calcined in a solid or ga3eous reducing
medium, at a temperature of about 1,000 C, whereupon the titanium
dioxide contained in the mineral in the form of the titanate
becomes transformed into rutile. The impuritie~, mainly iron
oxides, are then removed by means of sundry leaching processes,
leaving as a solid re~idue a concentrate with high content of
titanium dioxide meeting the specification~ of the consumers of
the product.
Innumerable re3earch efforts have been aimed at ob-
taining concentrates with a high content of ~iO2, starting with
minerals other than ilmenite, in which the titanium is in the
iorm of iron titanate. Attempt~ made ~o far have proved fruit-
les~, taking as starging point either minerals in which the
titanium is in the form of titanate3 other than of iron--such
3o as perovskite and titanite (aphene),-- or minerals in which the
titanium i8 in the form of oxides, suoh as anathasium and brukite
in the natural form. In the whole o~ the experimental techniques,
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even when h1gh contents of TiO2 are obtained, the impossibility
of removal of impurities ~trongly associated with titanium did
not permit obtainlng of a final product suitable for marketing.
The prohibitive prices of the prooesses tried out, in turn
discouraged any attempts at proceeding with studie~ in this
respect.
Anti-pollution legi~tation, in turn, beco~ing, a~ it is,
more and more ~trict in the whole of the developed or developing
countries, tend to a greater and greater e~tent to demand the use
of concentrates of minerals with a high content of titanium for
the manufacture of pigment~, a ~eotor responsible for the consump-
tion of about 75% of the titanium minerals produced in the world.
Thi~ tendency is aimed at reducing or even eliminating the pro-
duction of pollutant effluent~, such as occurs mainly in the
process of obtaining of ~iO2 by the sulphate proces~ u~ing
ilmenite as the raw material.
In the whole of the processes for concentration of
minerals at present known, the main disadvantage~ pointed out
are the need for using raw materials that meet certain specifica-
tions as regards content of impurities, especially phosphorus;the high temperatures at which reduction takes place; and the
considerable consumption of leaching solution due to the low
; content of titanium dioxide (TiO2) in the raw material. ~his
last disadvantage has been circumvented with the recovery of the
leaching solutions, but even 80 this approach calls for greater
investment with consequent increases in the price of the concen-
trate 80 obtained.
~ he invention here presented is intended precisely to
overcome these three disadvantages mentioned, 80 that it msy
become possible to obtain in mors economical form a concentrate
meeting consumer specifications.
- As raw material for the new process of concentration
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1083825
for obtaining products with contents of titanium oxide ~TiO2)
higher than 90%, use i8 made of minerals in which the latter
i9 present in the form of oxldes which are contaminated mainly
; but not e~clusively by the presence of compounds of iron, caloium,
magnesium, phosphorus, aluminum, sodium and potassium.
~ hi8 raw material, concentrated by any conventional
means, reaches contents of titanium dioxide amounting to a
ma~imum of 80%, beyond which point it i9 not possible to remove
the impurities contained, either mechanically or by ~uitable
means of leaching.
This conoentration of TiO2 would in itself make the
concentrate eligible ~or use in industries for the manufacture
of pigment~. Yet the presence of impurities such as phosphorus
disclassifies it for use in the sulphate process, ina~much as
since this element i8 an anti-rutilizing component, it does not
permit the obtaining of good quality rutile-type pigments and
i ~ cannot be eliminated by the manufacturing process.
~ he presence of alkaline and alkaline earth elements
disclassifies it in turn for use in the manufacture of pigments
by the chlorine process, inasmuch as its chlorides, which have
melting points in the range of operation of the chloration
reactors and do not volatilize within the latter, jeopardi~e
the fluidized bed normally used in this process, or form residual
products that are extremely detrimental to the operation of thi~ -
equipment.
These disadvantages do not occur with the use of tit-
anium concentrates obtained with the use of the present in-
vention, in the main stage of which 3ubmits the mineral to a
piro-metallurgical trèatment and feadies it for effective
hydrometallurgioal treatment suitable for effioiently removing
the harmful impurities.
This main advantage of this piro-metallurgical treatment
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is that, apart from its being cllrried out at temperatures
lower than that of rutilization of TiO2, furthermore permits
an increase in the content of TiO2 in the ore, by removal of
the iron through magnetic separation.
According to a process of the subject invention,
anatase ore is calcined in a non-reducing atmosphere at a
temperature below that of rurilization; the so obtained cal-
cined ore is cooled and reduced in a reducing atmosphere at
temperatures between 400C. and 600C.; then the reduced ore
is subjected to magnetic separation to produce a concentrated
titanium containing non-magnetic fraction; the non-magnetic
fraction is subjected to mineral acid leach to remove additional
impurities; and the acid leached fraction is neutralized and
washed to produce a concentrated titanium fraction.
The calcination of anatase ore is carried out at a
temperature below 900C., in a non-reducing atmosphere that
causes the limonite contained therein to become trasformed
into hematite. After this, the mineral thus calcined is
cooled and submitted to reduction by passing a reducing mixture
of poor gas containing at least l0% of reducing gas (CO or H).
In this operation, the hematite contained in the mineral
becomes transformed into magnetite. The larger size of the
Fe3O4 crystals causes a breakdown of the TiO2 crystals con-
taining them, thus releasing particles of magnetite while at
the same time exposing incrusted impurities which would not
have been attained and removed by subsequent leaching.
After the piro-metallurgical treatment the mineral
is subjected to magnetic separation in a magnetic field of
between 400 and 1500 gauss. In this operation, a part of the
iron is removed with consequent enrichment of the mineral.
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After the piro-metallurgical treatment, the rejects
from the magnetic separation are sent for hydro-metallurgical
treatment consisting of conventional leaching by means of an
acid solution. This operation permits removal, to limits
acceptable for marketing purposes, of the whole of the
impurities except the phosphorus, which is left adsorbed
into the mineral in the form of phosphoric acid.
For the removal of this phosphoric acid in residual
quantities, which might disqualify the product, the
concentrate is treated according to this invention with
alkaline solution in a concentration sufficient for trans-
forming the acid into
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10 83R3Z~5
soluble phosphote. Hence the residual pho~phorus i~ readily
removed by sub~equent washing.
EXAMPLE I
A mechanical concentrate of titaniu~ mineral containing
81.6% of TiO2 and 6.45% of total ~e, in a degree of finene~s
lower than 200 ~esh, wa~ taken to a rotary kiln and calcined at
750 for 30 minutes in an atmo~phere of C02. After thi~
treatment, the mineral was cooled to 500 C, and the C02 atmos-
phere was maintained. After reaching the 500C temperature, the
mineral wa~ reduced with a flow of reducing gas composed of 60%
of N, 24~ of C02 and 16% of CO, during a period of 45 minutes.
The material wa~ subjected to magnetic separation in humid
mediumJ in a field of 600 gauss, which gave ri~e to two fraction~,
one magnetic--10% of the original feed, with 40.71% of ~iO2 and
23.66% of total Fe--and one non-magnetic, with 86.66~ of TiO2
and 4.48~ of total Fe. RecoYery of TiO2 in this operation wa~
95.5%.
The one-magnetic fraction was leached with HCl 200 g/l
at 104 C, with stirring arrangement~, during a period of 4
hours. Subsequent to this operation the concentrate was ~eparat-
ed from the liquid phase by filtration and washed with water by
decantation until the acid had been removed. ~he concentrate
thu~ separated was treated with a solution of sodium h~droxide
at 5% and then washed with water to remove the alkali. The
re~ult~ obtained appear in the following table:
~echan- Magnet- Non-mag- ~eached Neutral-
ical con- ic frac- netic with ization
centrate tion fraction HCl with NaOH
TiO2, % 81.64 40.7186.66 90.3190.03
Total Fe, % 6.45 23.634.48 2.24 2.38
P205, % 0.66 3.04 0.66 0.16 0.03
Sio2, % 4.16 11.763.99 4.31 4.01
CaO, ~ 0.70 1.12 0.97 0.50 0.56
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Mechan- Magnet- Non-~ag- Leached ~Jeutral-
ical con- ic frac- netic with lzation
centrate tion fraction HCl with NaOH
MgO, %0.24 0.96 0.34 0.16 0.20
A12031.62 5.58 1.~7 0.81 1.06
EX~P~E II
A mechanical concentrate of titanium mineral contain-
ing 75.64~ of TiO2 and 8.21~ of total Fe, with a degree o~
fineness of 200 mesh, was placed in a rotary kiln and roasted
at 750 C of 60 minutes in an atmosphere of C02. After this
period, the mineral was cooled at 600 C, and kept in a C02
atmosphere. After the temperature of 600 C was reached, the
mineral was reduced in a flow of reducing gas containing 60~
of N, 14~ of C02, and 24~ of CO during a period of 45 minutes.
~he resultant material was subjected to magnetic separation in
humid mediu~ in a field of 800 gauss, which produced two fractions,
one, magnetic--10% of the original feed, containing 42~4~o of
TiO2 and 31.98~ of total Fe--and the other, non-magnetic, with -
79.27% of ~iO2 and 5. 22~o of total Fe. ~he proportion of TiO2
recovered in this ~eparation proce~s amounted to 94.~ of ~iO2.
The non-magnetic fraction was leached with HCl 200 ~/1
at 104 C, under stirring, for four hours. After this operation
the concentrate was separate in the liquid phase by filtration
and wa~hed with water b~ decantation after removal of-the acid.
The separated concentrate wa~ treated with a solution
of ~odium hydroxide at 2% and then wa~hed with acid until removal
of the alkali. ~he results obtained are given in this following
table~
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Mechan- Magnet- Non-mag- ~eached Neutral-
ical con- ic frac- netic with ization
centrate tion fraction HCl with NaOH
TiO2, ~ 75.64 42.4879.27 89.93 93.26
lotal Fe, %8 . 21~1. 985, 22 2 . 01 1. 99
P205' ~ 2.11 0.55 2.07 2.10 0.22
SiO2, % 0.52 0.09 0.49 0.48 0.46
CaO, % 1.12 2.20 1.06 0.25 0.27
MgO, % 0.50 0.90 0.47 0.08 0.05
A1203, % 2.88 4.00 2.72 1.50 1.41
The examples given above are presented for the clarifi-
cation o~ those ~ersed in the art but are by no means intended
as limitations of the invention.
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