NO830353L - PROCEDURE FOR THE PREPARATION OF TITANIUM Dioxide CONCENTRATES - Google Patents

Description

The invention relates to a method for producing titanium dioxide concentrates by removing iron from iron oxide-containing titanium oxide-containing material using chlorine-containing gases.

From US patent 2,184,885, a method for removing iron from an iron-titanium ore is known, where a good mixture of the ore is chlorinated with 1-12% by weight of carbon at temperatures above 500°C, the main part of the iron and noticeable amounts of titanium evaporate as chlorides. The remaining residue essentially consists of titanium dioxide with only a small iron content.

In the method for the preparation of iron and titanium oxide-containing ores according to British patent 1,359,882, a mixture of the ore with 20-40% carbon by weight is treated at 800-1000°C in a fluidized bed reactor with a gas mixture which, in addition to nitrogen, contains 20- 50 volume% chlorine and 0-10 volume% oxygen. Thereby, iron oxide is mainly transferred to iron II chloride.

The unfortunate thing about the first-mentioned method is that, with regard to its selectivity, it is difficult to control, while the iron-II chloride formed in the last-mentioned method is significantly less volatile than iron-III chloride, and acts extremely corrosive at higher temperatures.

It is therefore the task of the invention to provide a method for removing iron from iron oxide-containing titanium oxide-containing material with chlorine-containing gases, where the iron oxides are volatilized with high selectivity as iron III chloride. This is achieved according to the invention by reacting the titanium oxide-containing material which is kept in motion with a gas mixture consisting of at least 70 vol% chlorine, possibly an inert gas in a reaction zone heated to 800-1300°C, the iron III chloride formed being volatilized and remains a residue consisting essentially of titanium dioxide.

The method according to the invention can, by choice, also be designed in that:

a) material containing titanium oxide is allowed to move in the direction of gravity and treated with the gas mixture in counter-current, b) material containing titanium oxide is stirred with the gas mixture, c) material containing titanium oxide is allowed to trickle in free fall through the vertically arranged reaction zone and

treated in countercurrent with the gas mixture,

d) nitrogen serves as an inert gas,

e) the gas mixture contains at least 85% chlorine by volume,

f) the reaction zone is heated from 900 to 1100°C,

g) the reaction zone is heated to at least 1000°C.

In the method according to the invention, ilmenite (main constituents: FeTi03, Fe203, Ti02), leucoxene (weathering product of ilminite) or titanomagnetite (main constituents: Fe^O^,

Fe 2 O 3 , TiO 2 ).

In the method according to the invention, the use of a titanium oxide-containing material which also contains oxidatively bound vanadium, at the same time vanadium as chloride or oxychloride, is volatilized.

With the method according to the invention, the iron content in the chlorination residue can be practically set as desired with sufficient reaction time, without any significant formation of TiCl^ occurring. Moreover, the reaction system is also highly insensitive to apparatus changes.

In the method according to the invention, the iron has the dignity

and bond type in the titanium oxide-containing material no effect on the completeness of the separation of the iron.

In the method according to the invention, by stirring up the

the titanium oxide-containing material, the flow rate of the gas mixture must be at least so great that sintering or sticking together is prevented. However, the selectivity is practically not affected

at higher flow rates. -

It is advantageous in the method according to the invention

when the titanium oxide-containing material in a finer distribution is brought into contact with the chlorine-containing gases.

In the following examples, percentages indicate - when nothing else is noted - % by weight.

Example 1 (Comparison example)

A horizontally arranged quartz tube (50 mm 0) was filled

200 g of ilminite with a storage density of 24 00 g/l, and of composition 53.5% Ti02, 21.5% FeO, 20.9% Fe203, 0.9% Al203, 0.5% Si02, 0.01% CaO and 0.13% V 2 O 5 . The quartz tube was heated to 1000°C and chlorine gas passed through at a flow rate of 0.5 cm/sec. After 60 minutes, the initially strong FeCl3~evolution recedes considerably and after a further 30 minutes it has practically ended. Now an inhomogeneous, solid caked-on product was taken out of the quartz tube which had obviously only reacted with the chlorine on the surface and has an average fat content of 34.3%.

Example 2 (according to the invention)

In a vertically standing quartz tube (40 mm 0) with fused Dl frit, 80 g of ilmenite with a storage density of 2400 g/l and of composition 53.5% Ti02, 21.5% FeO, 20.9% Fe203, 0, 9% A12<0>3, 0.5% SiO2, 0.01% CaO and 0.13% V"205 heated while stirring with nitrogen to 1090°C. While maintaining this temperature, it was then passed through chlorine as a vortex gas with a flow rate of 5.0 to 5.5 cm/sec (referred to normal conditions and to the empty quartz tube). The gaseous iron III chloride which immediately forms was sensed in downstream separation vessels. The chlorination was carried out for 30 my.

As a residue, 3.5 g of a loose grey-white powder with a Ti02 content of 97.7%, as well as with 0.3%

iron and 0.0027% vanadium.

The TiC^ loss during volatilization of co-formed titanium IV chloride amounted to less than 1%, referred to the TiO 2 contained in the ilmenite.

Example 3 (according to the invention)

Example 2 was repeated with the change that the chlorination was carried out at 1010°C.

The residue remaining in the quartz tube (44.2 g) has a TiC>2 content of 95.7%. Furthermore, it contained 0.8% iron and 0.005% vanadium.

The TiC^ loss during volatilization of co-formed titanium IV chloride amounted to less than 0.5%, referred to the TiC>2 contained in the ilmenite.

Example 4 (according to the invention)

Example 2 was repeated with the change that the chlorination was carried out at 950°C.

The residue formed in the quartz tube (47.0 g) has a TiO2 content of 93.0%. Furthermore, it contains 3.7% iron and 0.006% vanadium. TiCl^ mist was not observed in the exhaust gas.

Example 5 (according to the invention)

In the device mentioned in Example 2, 120 g of titanomagnetite with a storage density of 2550 g/l and of composition 28.4% Ti02, 51.8% Fe and 0.2% V were heated while stirring with nitrogen to 980°C . While maintaining this temperature, chlorine was then passed through as vortex gas at a flow rate of 6.0 to 6.5 cm/sec. (referred to normal conditions and to the empty quartz tube). The gaseous iron III chloride that spontaneously forms was precipitated in downstream separation vessels. The chlorination was carried out for 20 minutes.

As a residue, 35.8 g of a loose gray powder with a TiC^ content of 95.2%, as well as 1.9% iron and 0.005% vanadium remained in the quartz tube.

The TiC^ loss by volatilization of co-formed titanium IV chloride amounted to less than 0.5%, referred to the TiO 2 contained in titanomagnetite.

Example 6 (according to the invention)

In the apparatus described in Example 2, 40 g of the ilmenite used in the same example was heated to 1000°C while stirring with nitrogen. While maintaining this low temperature, a mixture of 85 vol.% chlorine and 15 vol.% nitrogen was then passed through as vortex gas with a flow rate of 3.8 cm/sec. (referred to normal conditions and on the empty quartz tube). The gaseous iron III chloride that forms was precipitated in downstream separation vessels. The chlorination was carried out for 20 minutes.

As a residue, 22.3 g of a loose grey-white powder with a Ti02 content of 96%, as well as 1.0% iron and 0.004% vanadium, remained in the quartz tube.

The Ti02 loss during volatilization of co-formed titanium IV chloride amounted to less than 0.5% referred to the Ti02 contained in the ilmenite.

Example 7 (according to the invention)

In the apparatus mentioned in example 2, 40 g of the ilmenite in the same example was heated to 1050°C while stirring with nitrogen. While maintaining this temperature, a mixture of 75 vol.% chlorine and 25 vol.% nitrogen was then passed through as swirling gas at a flow rate of 3.8 cm/sec. (referred to normal conditions and to the empty quartz tube). The iron III chloride that forms was precipitated in downstream separation vessels. The chlorination was carried out for 20 minutes.

As a residue, 22.0 g of a loose grey-white powder with a TiC^ content of 97.2%, as well as with 0.5% iron and 0.004% vanadium, remained in the quartz tube.

The TiC^ loss by volatilization of co-formed titanium IV chloride amounted to less than 1% referred to the TiO 2 contained in the ilmenite.

Example 8 (according to the invention)

Example 7 was repeated with the modification that the chlorination temperature was only 950°C.

As a residue, 23.6 g of a loose grey-white powder with a Ti02 content of 92.8%, as well as 3.9% iron and 0.006% vanadium, remained in the quartz tube.

TiCl^ mist was not observed in the exhaust gas.

Example 9 (according to the invention)

A vertically standing quartz pipe (50 mm Øj length: 80 cm) was equipped at its lower end with a lower shut-off valve and at its upper end connected to one with ilmenite according to Ex. 2 filled solids storage container which at its lower end is equipped with a shut-off tap enabled a continuous or discontinuous addition of ilmenite. Above the lower shut-off valve on the quartz tube, chlorination gas could be introduced outside the reaction zone via a side connection. Furthermore, a further movable quartz tube was introduced at the upper end of the quartz tube, which served for possible sugaring and to control the flowability of the ilmenite. Gaseous reaction products could escape over the reaction zone via a side nozzle from quartz

the pipe.

In the first row, the vertically standing quartz pipe was filled from the lower shut-off valve up to half of the approx. 20 cm long heated zone with rutile (96% TiC^). During the passage of chlorine gas with a flow rate of 0.6 cm/sec., said zone was heated to 1000°C and held at this temperature. Then, from the solids storage container, approx. 2 g ilmenite per minute into the quartz tube. After 30 minutes, approximately the same amount per minute of the pre-filled rutile removed. After 60 minutes, the dosing of ilmenite was terminated, however, the passage of chlorine gas continued for another 15 minutes. After cooling, a sample with a TiC content of 95.0%, as well as with 2.3% iron and 0.009% vanadium, was taken from the mostly loose reaction mixture. The TiC^ loss by volatilization of co-formed titanium IV chloride amounted to less than 0.5%, referred to the TiO 2 contained in the ilmenite.

Example 10 (according to the invention)

Example 9 was repeated with the change that the implementation

of chlorine gas was carried out at a temperature of the heated zone of 1050°C.

A sample taken after cooling the loose reaction mixture has a Ti02~ content of 96.2%, as well as 1.2% iron and 0.008% vanadium.

The TiC^ loss during volatilization of co-formed titanium IV chloride amounted to less than 1%, referred to the TiO 2 contained in the ilmenite.

Example 11 (according to the invention)

Example 9 was repeated with the change that instead of chlorine gas, a gas mixture consisting of 90% by volume chlorine and 10% by volume nitrogen was passed through the heated zone with a flow rate of 0.7 cm/sec.

A sample taken after cooling the loose reaction mixture shows a Ti02~ content of 94.6%, as well as 2.1% Fe and 0.010% vanadium.

The TiC^ loss by volatilization of co-formed titanium IV chloride amounted to less than 0.5%, referred to the TiO 2 contained in the ilmenite.

Example 12 (according to the invention)

Example 9 was repeated with the change that instead of chlorine gas, a gas mixture consisting of 85 vol% chlorine and 15 vol% nitrogen was used with a flow rate of

0.7 cm/sec. and that the gas mixture was passed through the zone heated to 97 0°C.

A sample taken after cooling the loose reaction mixture shows a Ti02~ content of 92.2%, as well as 4.1% iron and 0.015% vanadium.

The TiO 2 loss during volatilization of co-formed titanium IV chloride amounted to less than 0.5%, referred to the TiO 2 contained in the ilmenite.

Example 13 (according to the invention)

In a vertically arranged quartz tube (27 mm 0, 300 cm length) 107 g/hour of ilmenite of composition 53.5% TiC>2, 21.5% FeO, 20.9% Fe2O3, 0.9% Al were dosed 03, 0.5% SiO2 and 0.13% V2O5, as well as a grain size range from 63 to 610 ym and was treated in free fall at 1090°C with countercurrent chlorine (150 l/h). The thereby formed gaseous iron III chloride was precipitated in subsequent separation vessels. The excess chlorine was condensed and the amount of the remaining off-gas consisting of oxygen monitored volumetrically.

At the lower end of the quartz tube, after 60 minutes, 65.2 g of a light, friable residue with a Ti02 ~ content had formed

of 91.6%, as well as with 4.1% iron.

The Ti02~ loss during volatilization of co-formed titanium IV chloride amounted to less than 0.1% referred to the Ti02 contained in the ilmenite.

Example 14 (according to the invention)

Example 13 was repeated with the change that 200 l/t chlorine was introduced.

At the lower end of the quartz tube, after 45 minutes, 47.5 g of a bright, friable residue with a TiO 2 content of 95.8% and 0.6% iron had formed.

The Ti02~ loss during volatilization of co-formed titanium IV chloride amounted to less than 0.1% referred to the Ti02 contained in the ilmenite.

Example 15 (according to the invention)

Analogous to Example 13, 321 g/t ilmenite with a grain size range from 100 to 149 ym was treated with 450 1 chlorine per hour.

At the lower end of the quartz tube, after 30 minutes, 93.8 g of a bright, friable residue with a Ti02 content of 96.0% and 0.5% iron had formed.

TiCl^ mist was not observed in the exhaust.

Example 16 (according to the invention)

Example 15 was repeated with the change that the treatment of ilmenite with chlorine took place at 1030°C.

At the lower end of the quartz tube, after 30 minutes, 108.5 g of a friable residue with a TiO 2 content of 83.0% and 9.8% iron had formed.

TiCl^ mist was not observed in the exhaust.

Example 17 (according to the invention)

Analogous to Example 13, 530 g/t ilmenite with a grain size range from 100 to 149 ym was treated with 600 1 chlorine per hour.

At the lower end of the quartz tube, after 60 minutes, 33 9 g of a friable residue with a TiC 2 content of 88.1% and with 6.8% iron had formed.

The Ti02 loss during volatilization of co-formed titanium (IV) chloride amounted to less than 0.1% referred to the Ti02 contained in the ilmenite.

Example 18 (according to the invention)

In a vertically arranged quartz tube (50 mm 0.700 cm length) 705 g/t of ilmenite of the composition and grain size used in Example 1 was dosed and treated in free fall at 10 50°C with counter-flowing chlorine (750 l/h ). The thereby formed gaseous iron -(III) chloride was precipitated in subsequent precipitation vessels. The excess chlorine was condensed and the amount of the remaining off-gas consisting of oxygen monitored volumetrically.

At the lower end of the quartz tube, after 60 minutes, 417 g of a bright, friable residue with a TiO 2 content of 95.6% and 0.4% iron had formed.

The Ti02~ loss during volatilization of co-formed titanium (IV) chloride amounted to less than 0.1% referred to the Ti02 contained in the ilmenite.

Example 19 (according to the invention)

Analogously to Example 18, 13 20 g/t of ilmenite was obtained from that in Ex. 1 used composition and grain size treated with 1200 l/h

chlorine.

At the lower end of the quartz tube, after 60 minutes, 785 g of a light, friable residue with a Ti02~ content of 94.5% and with 0.6% iron had formed.

The TiO 2 loss during volatilization of co-formed titanium (IV) chloride amounted to less than 0.1%, referred to the TiO 2 contained in the ilmenite.

Example 20 (according to the invention)

Example 13 was repeated with the change that the ilmenite was treated with 170 l/h of a gas mixture consisting of 88 volume% chlorine and 12 volume% nitrogen.

At the lower end of the quartz tube, after 60 minutes, 64.5 g of a friable residue with a Ti02 content of 91.1% and 4.2% iron had formed.

The Ti02~ loss during volatilization of co-formed titanium (IV) chloride amounted to less than 0.1% referred to the Ti02 contained in the ilmenite.

Example 21 (according to the invention)

Example 18 was repeated with the change that the ilmenite was treated with 900 l/h of a gas mixture consisting of 83% by volume chlorine and 17% by volume nitrogen.

At the lower end of the quartz tube, after 60 minutes, 414 g of a bright, friable residue with a TiO 2 content of 93.5% and 1.8% iron had formed.

The Ti02 loss during volatilization of co-formed titanium (IV) chloride amounted to less than 0.1% referred to the Ti02 contained in the ilmenite.

Claims (8)

1. Process for the production of titanium dioxide concentrates by removing iron from iron oxide-containing titanium dioxide-containing material using chlorine-containing gases, characterized in that the titanium oxide-containing material kept in motion is reacted with a gas mixture consisting of at least 70% by volume chlorine and possibly an inert gas in a to 800 reaction zone heated to 1300°C, as the iron-III chloride formed is volatilized and a residue consisting essentially of titanium dioxide remains. 2. Method according to claim 1, characterized in that titanium oxide-containing material moves in the direction of gravity and is treated with the gas mixture in counter-flow. 3. Method according to claim 1, characterized in that a material containing titanium oxide is stirred up with the gas mixture. 4. Method according to claim 1, characterized in that the titanium oxide-containing material is allowed to trickle in free fall through the vertically arranged reaction zone and is treated in countercurrent with the gas mixture. 5. Method according to one of claims 1-4, characterized in that nitrogen is used as inert gas. 6. Method according to one of claims 1-5, characterized in that the gas mixture contains at least 85% chlorine by volume. 7. Method according to one of claims 1-6, characterized in that the reaction zone is heated to 900-100°C. 8. Method according to claim 7, characterized in that the reaction zone is heated to at least 1000°C.