DE1203236B - Process for the production of oxides of titanium, aluminum, zirconium or hafnium - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

BOIj

German class: 12 g-5/01

Number: 1203 236

File number: B 52353IV a / 12 g

Filing date: March 4, 1959

Opening day: October 21, 1965

In British Patent 761,770 there is one method for the production of titanium dioxide described in the titanium tetrachloride by means of air or other Oxygen-containing gases is oxidized by introducing the titanium tetrachloride into a fluidized bed of inert Particulate material with particle sizes of approximately 40 to 1000 μ. The resulting oxides are also in this known method, at least for the most part, by getting out of bed escaping gases entrained. Also is in the UK Patent specification already contained the proposal to maintain the heat released during the reaction to use the reaction temperature in the fluidized bed. Flow through the reactants in this process, before entering the bed, a plate with perforations, the Pressure drop is at least equal to half the pressure drop across the bed.

The method according to the British patent has proven itself when the oxidation of titanium tetrachloride should be carried out in the laboratory.

The invention is now based on the object of a fluidized bed process for autothermal oxidation to create the metal chlorides on an industrial scale, in which an additional heating with all its disadvantages is avoided.

Based on the method of the British patent, this object is achieved in that the dimensions of the bed with a minimum diameter of 38 cm and a static height of the inert solid material of 30 to 90 cm and the flow rate of the gases between the 2 to 50 times the minimum speed necessary for bringing about the flow state can be set in such a way that sufficient heat is stored in the bed in a manner known per se to keep the reaction going, on the other hand the temperature in the bed in a likewise known manner by exchanging inert solid material controlled by cooler material to a value below 1200 ⁰ C, preferably below HOO ⁰ C, and the total increase in oxide on the bed material is kept below 20% of the bed weight by continuous or recurring cleaning and that the reactants before entering the bed through throttling points being directed s in which, in a known manner, there is a pressure drop of at least half the size of the pressure drop in the bed.

The reaction of the metal halides with oxygen is an exothermic one. Yet it is extraordinarily

Process for the preparation of oxides of
Titanium, aluminum, zirconium or hafnium

Applicant:

British Titan Products Company Limited,

Billingham, Durham (UK)

Representative:

Dipl.-Ing. F. Weickmann

and Dr.-Ing. A. Weickmann, patent attorneys,

Munich 27, Möhlstr. 22nd

Named as inventor:

Arthur Wallace Evans, Middlesbrough,

Yorkshire;

William Hughes, Stockton-on-Tees, Durham

(Great Britain)

Claimed priority:

Great Britain March 4, 1958 (6988)

borrowed difficult to use the heat released during the reaction to heat the subsequent reaction participants. The indication that the action is an exothermic, and that with sufficient insulation of the reaction space that caused by the exothermic The heat generated by the reaction could be sufficient (British patent specification 761770, p. 3, column 1, Lines 34 to 37) has not yet specified a procedure which can be used on an industrial scale. This means that the heat released during the reaction is used to heat the subsequent reaction participants can be used, it is necessary that the amount of inert solid material in the bed is such sized and the dimensions of the bed are chosen so that the bed has sufficient warmth stores to keep the reaction going on the one hand, but on the other hand the temperature does not exceed -1200 ° C, preferably 1100 ° C to rise. It is further required that there be effective temperature control is created. This is done according to the invention in that inert solid material is withdrawn and replaced. It should also be noted that in the course of the reaction on the inert Solid material accretions of oxides occur and that these accretions of oxides the Particle size of the inert solid material

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change. It is now known that the size of the particles. These substances can also be treated with chlorine at high temperatures, which determines the ratio of weight to temperature, so that all undesirable surfaces. This ratio is for the heat impurities are eliminated. The size transition responsible. If, in the course of the moderate composition of the bed material, the particle size of the bed material in the reaction is essentially such that the diameter of the increases, the heat transfer particles deteriorate essentially not less than 76 μ conditions in the bed with the Consequence that the and not greater than 1000 μ. In no case may subsequent reactants no longer be in the particles smaller than 40 μ.
be heated sufficiently and the reacting zirconium silicate sand with a particle size of tion comes to a standstill. For this reason io 150 μ is a preferred bed material, namely the condition that the accretions on the because it is relatively hard and because it is kept solid material below 20% against the secondary problems arising from the oxidation, of considerable Significance for the discharge duct chlorine is resistant. The particle density of a large-scale process. If that is to say approximately the density of the mineral, first of all all other conditions on the disruptive 15 The bed material should be such that the reaction can run freely, so the reaction would stop very soon after treatment in an air stream, if the oxide 1000 ° C for 100 hours with a gas velocity increase on the particles, the specified speed, which is five times as large as the minimum flow limit of 20% significantly exceed. Closing bed speed, a proportion of dust of not borrowed for the autothermal reaction is also 20 more than 5% of the original total amount on the further requirement of the newly submitted instruction.

claim of great importance that the gaseous When starting up the bed in one through Reactants fed air into the inlet openings on the floor from below through throttling points in which the pressure drop is set in the flow condition and by a bestens equal to half the value of the pressure drop in 25 heating device, which is introduced into the bed the bed is. This requirement is necessary so that it is preheated. This is how the bed becomes a steady flow state is obtained. Only give a temperature of approximately 1000 ° C a steady flow condition is guaranteed. The heating device is then used given that the entire bed material is always excepted and the opening through which it is fed the heat transfer is used. 30 leads was locked. The airflow will now

Only if the above enumerated and turned off in. For this, oxygen or an oxygen is used Meaning individually discussed combination containing gas introduced by the for the Overall compliance with the measures is practical in introducing oxygen during the procedure large technical scale a successful entry openings. The autothermal reaction possible for the chloride-rich. 35 introducing certain entry openings and passages

At least one of the participants in the reaction should start with a stream of Stickmit one flushed out of the substance for the generation of the flow state; then the chloride is submerged Speed introduced into the bed leads.

will. The gas velocity in the bed is The oxide obtained is out of the bed with the

preferably to a value of at least 40 chlorine-containing gaseous reaction products

8 cm / sec held. carried. The temperature of this mixture of gas

On the walls of the reaction chamber is pre- and finely distributed solids as they exit the preferably introduced oxygen. One avoids that bed is in the region of 900 to 1200 ° C. There by an excessive reaction on the wall the gases have a corrosive effect, it is necessary to use them of the reaction space. The insulation of the introductory 45 to cool while it is still within the with Lines at the lower end of the reactor should be lined with a possible chlorine-resistant material can be good so that they are located in the reaction chamber. There are various methods of wrapping Heat from the introducers has been suggested to guide this cooling will. In addition to the bed-under there is a water-based deterrent temperature control process or by returning cool gases. To This can also be reduced by cooling the cooling down to at least 400 ° C River bed can be reached. the gases are cooled by known cooling systems

The pressure drop at the throttle positions is in forwards before it is subsequently collected and / or in

usually greater than 0.14 at, the total pressure drop gas and oxide are decomposed. The severed ones

at the constrictions and in the bed larger than 0.21 at, 55 oxides are then cleaned in a suitable manner,

but hardly greater than 7 at. It is true that most of the gained

The temperature of the fluidized bed, the very general oxide carried off by the reaction gases; A mine is below 1200 ° C, preferably a small part of the oxide moves but remains on the bed mateweise between 900 and 1100 ° C. Particularly good rial adhere. By the replacement of the bed material results are obtained in the range from 970 to 60, this on the one hand cleaned of Oxydansätzen 1020 ⁰ C. are; on the other hand, the bed can be so chilled

The granular, inert solids that are the re-.

Form an action bed can be made of zirconium silicate, The proportions of the reactants correspond

mineral rutile and aluminum oxide. the stoichiometric molar ratio of oxygen

The main condition is that the bedding materials become chloride against chlorine 65, but can be between 0.75: 1 and 4: 1

and chlorine-containing substances, which are in the range of, preferably between 1.1: 1 and 2: 1. Ever

Oxidation process could occur, in which the greater the molar ratio, the more difficult

are resistant to coming temperatures. it becomes an autothermal reaction temperature too

receive. Therefore, the molar ratios at the upper limit will not be used if one wants to generate temperatures at the upper limit of the range at 1200 ° C. In this case it will rather a molar ratio of about 2: 1 use.

The gases can be used in a relatively dry state. she but can also contain moisture within certain limits, e.g. up to 5%. You can with this Moisture content achieve some regulation. The oxygen content in particular may contain moisture. The presence of large amounts of water must should therefore be avoided, as they can convert the chlorine into hydrochloric acid. aside from that hydrogen is formed in the presence of hydrochloric acid. This hydrogen must come from the HCl vapor separated, which makes further safety precautions necessary.

The figures show exemplary embodiments. It shows

1 shows an elevation, partly in section, of a reaction chamber designed as a shaft furnace a feeding device for the solids forming the bed, a collecting device for the Solids and a cooling system,

F i g. 2 is a plan view of the gas introduction system selected in the illustration of FIG. 1,

3 shows an enlarged partial view of FIG. 1, FIG. 4 is a plan view of FIG. 3,

Fig. 5 is an enlarged elevation, partly in section, of a modified embodiment;

FIG. 6 is a plan view of FIG. 5.

In Fig. 1, the reference numeral 1 designates a reaction chamber, which is with a chlorine-resistant Lining 2 is provided. This is surrounded on its outside by an insulating layer 3, and the whole is in a steel jacket 5 with an upper opening 6 and a bottom opening ?. Neck tubes 8, which terminate in flanges 9, are welded into these two openings. The reaction chamber is set up vertically.

A ceramic block 11 is attached to a metallic base plate 10. The ceramic block 11 serves as insulation between the reaction space and the base plate 10. The base plate 10 is provided with openings 13. These perforations coincide with through-holes 12 of the ceramic block 11. The openings 13 and the through-holes 12 are distributed in the plate or the block according to the pattern shown in FIG.

The through-bores 12 are staggered into the group 112 for the introduction of chloride and into a group 212, 312 for the introduction of oxygen. The through-holes of group 112 are arranged in the form of a regular octagon. Likewise, the through bores 212 are arranged in the form of a larger regular octagon; finally there is a through hole 312 in the center.

In the upper exits of the through-holes of the ceramic block 11 gas-permeable bodies can be inserted, which prevent the penetration of solids of the bed into the through-holes. Such gas-permeable bodies are z. B. described in British Patent 724 193.

Preferably, however, such gas-permeable bodies are dispensed with and the through-holes 12 are made so narrow that the speed of the reactants is sufficient to prevent solid substances from the bed from falling into the through-holes.

A manifold 25 supplies oxygen to the through bores 212 and 312, while another manifold 26 supplies chloride vapor into the

ίο Piercing 112 is initiated. Pipes 41 (FIG. 3) are connected to all through bores 12. These are welded into the plate and equipped with flanges 104 at their lower ends. A mating flange 105 is connected to each of the flanges, from which a line 42 leads to the collecting lines 25 and 26 for oxygen or chloride. A disk 43 with a throttle point 47 is inserted between each of the flange pairs 104 and 105.

ao In Fig. 3, the use of gas-permeable bodies 102, 202 and 302 is shown. These have the task of preventing the penetration of solids from the fluidized bed into the through-holes and are inserted into the upper exits of the through-holes. For this purpose, the through bores are widened at their upper outlets 15. The gas-permeable bodies of the oxygen system have larger diameters than the gas-permeable bodies in the perforations of the chloride system.

A modified embodiment is shown in FIGS. Here you can find heat-resistant pipes 400 which, for. B. consist of aluminum silicate. These are inserted into bores in the insulating block 11 and provided with outlet openings at their upper ends at 410. Pipes 41 are welded into the base plate 10 and extend into the pipes 400 . Pipe sockets 401 are attached to the lower ends of the pipes 41; these take screw plugs 402 with the throttle points 403 . Some of the tubes are connected to lower extensions. With these pipes, the pipe sockets are only attached to the end of the extension pieces. The non-elongated tubes open into a pressure chamber 404, while the elongated tubes open into a pressure chamber 405 .

The pressure chamber 404 is supplied with oxygen via an inlet 406 ; the pressure chamber 405 is supplied with chloride via an inlet 407 . The gas passages intended for oxygen form groups 408, while the gas passages intended for chloride form groups 409 in between. In this embodiment too, the pressure chambers can of course be replaced by collecting lines.

In FIG. 1, the reaction chamber is covered at its upper end by a closure plate 40. This is attached to the upper flange 9.

A ceramic insulating block 140 covers the closure plate 40 from the inside of the reaction space. A passage 24 for the introduction of the bed material is provided in the closure plate. The bed material is fed from a loading device 71 , which is shown schematically in FIG. 1. The loading device consists of a steel tube about 1.5 m long with an inside diameter of about

7 8

15 cm. The lower part of this steel tube is conical. Ceramic block 11 consists of chlorine-resistant Beverjüngt. The conically tapered part closes with a 23 cm thick clay. The openings or a tube 72 of about 5 cm in diameter. Through bores are 36.5 mm in diameter and compressed air is supplied through the pipe 72. About are evenly according to the scheme of F i g. 6 on the tapered part there is a perforated 5 part. On the underside of the plate 10 , the Lei plate 73 with openings of about 1.6 mm lines and manifolds are installed, which in diameters, which are shown at intervals of 1.25 cm according to FIGS. 1, 3 and 6,
arranged in a square pattern. The two outer rows, each with three upper parts of the tube 71, is cut over a length of about 90 cm and the innermost row with five passages is halved. Where the halving begins at an oxygen or air collecting line, the full pipe 71 is closed by a steel plate, while the two inner rows with

74 covered. A pipe 70 with a diameter of 5 cm has four passages connected to a titanium tetrachloride collector leading from the charging device at an angle to the line. The diameter of the bottom to the reaction chamber 1, a steel plate throttling points in the titanium tetrachloride feed lines

75 divides the fully cylindrical section of the 15 is 6.4 mm. The diameter in the oxygen tube 71. This steel plate extends to about 19 cm, leads are 4 mm.

via the perforated plate 73. The task of the opening 126 for the exit of the gas sus-

Steel plate suspended in the fully cylindrical part of the tube titanium dioxide has a diameter of

71 is to prevent gases from entering the reactor 30 cm. The TiO ₂ comes at a temperature between

penetration space into the loading device. 20 see 900 and 1000 ⁰ C from the reaction zone.

In the side wall of the furnace 1 is an opening. The conduit 77 has an inner diameter

126 provided. 10 cm pass through these openings 126. It is at 45 ° to the vertical

the reaction products in the further processing tends,

appliances. Through the opening 24 a heating device can

From the reaction space of FIG. 1 rises approximately ag direction are introduced, which the preheating 60 cm above the bottom of a line 77. This serves the bed. Here, however, bed material can also be fed in from a heat-resistant and chlorine-resistant line by producing the feed material and connecting it to a winch 71 .

angle of 45 ° inclined to the horizontal according to The plant is under the following conditions below. When solid bed material is in operation, this line opens out with a continuous exchange of zirconium silicate sand, with its cut-off particle diameter of 150 μ, the lower end leads over a flange 78 into a lateral branch, so that the static height of the bed in the junction 170 of a vertical tube 79. Reaction space 1 is 90 cm. This bed is The pipe 79, the inner diameter of which is about 8 cm, brought into a state of flow by means of air which carries through it, the collecting line and subsequent branch lines 81 are tightly inserted into a cover 80 of a mild steel vessel 35. The mild steel vessel 81 has one inserted. By means of a heating device, diameter of 20 cm and is 60 cm high. That which is introduced through the opening 24 in the upper part of the tube 79 up to a height of 8 cm above the reaction chamber, the bed then becomes the tapered end of the vessel 81 into this. preheated to a temperature of 1100 ° C. The heater immediately below the lower end of the tube 40 is then removed. For this purpose 79 is a plate 82 made of stainless steel to which the loading device 71 is connected. Wall thickness of 1.25 mm attached. In addition, the air supply used to produce the flow state fractures of this plate has a diameter of the air supply used and replaced by one of 1.6 mm and is replaced by a square oxygen supply, namely 9301 are arranged in patterns at 5 cm intervals. In one 45 minutes (measured under atmospheric conditions of about 15 cm below the upper end) supplied; through the inlet openings intended for the introduction of the vessel 81 there is a small branch 84. Titanium tetrachloride will see through which fluidized bed gases are discharged. A pipe 85 connects to the lower end of the vessel 81 in the supply system for titanium tetrachloride, in order to remove the air held by a compressed air 50; then the stick container leads. The material supply interrupted above the perforated plate 82 and replaced by titanium tetrachloride is fed into a cooling jacket 86. 5 kg of TiCl ₃ are included every minute, through which cooling water flows. The cooled bed material is drawn off through an evaporation line 83 surrounded by a steam jacket. tube inserted and completely evaporated there. So-

The following examples illustrate the invention and then introduce it into the feed bed and make it. All gas throughputs are based on its arrival in the reaction zone. The titanium assumption of atmospheric temperature and pressure tetrachloride reacts with the oxygen in the bed conditions. which TiCl _{4 is made} to flow by the flow rate of Example 1. The reaction

60 products leave the reaction area through the

The reactor consists of a vertical, Stahl outlet opening 126. Subsequently, the gases

NEN shaft furnace, as it is essentially shown in FIG. 1 the usual cooling and separating devices

is shown. Its total height is 4 m. The leads in which the titanium dioxide is collected. the

Furnace is inside with a chlorine resistant layer 2 temperature in the bed which is the reaction zone

lined, the thickness of which is 30 cm. This forms 65 is kept at around 980 ° C throughout.

Layer is on a 15 cm thick outer heat. Overheating is prevented by the circulating

insulating layer 3 attached. The inside diameter coniurasilicate sand over the feeder

diameter of the reaction space is 60 cm. The 71 in an amount of about 18 kg / hour. fed

is, and that the overflowing part of the bed is introduced through the line 77 into a collecting device 79 is to be cooled there, freed of chlorine and finally discharged through line 83. The titanium dioxide obtained is freed from the absorbed chlorine gas and is ultimately stored as a finely divided pigment of excellent white color. Its coloring power is 1300 units on the Reynold scale.

Example 2

IO

The procedure is carried out under the same conditions as in Example 1. The only one The difference is that so much water is added to the oxygen stream that it contains 2% titanium tetrachloride reacted. The resulting titanium dioxide is a finely divided pigment with a rutile content of 96.2, excellent white color and a coloring power of 1500.

Example 3

The process and equipment are the same as in Example 1. This applies in particular to the gas distribution, the bed conditions and the original bed temperature. The oxygen is supplied through the manifold 25 in an amount of 7551 per minute. After the manifold 26 has been purged with nitrogen, vaporized aluminum trichloride is introduced into the bed. The aluminum trichloride throughput is 3.8 kg per minute. Finely divided aluminum oxide emerges from the bed in a stream of chlorine and flows out of the reaction chamber through the outlet openings 126. The gases are then fed to the usual cooling and separation systems.

The temperature of the reaction zone formed in the bed is maintained at approximately 1000 ° C. For this purpose, zirconium silicate sand is fed via the loading device 71 in an amount of 95 kg each Hour fed. The excess portions of the bed are discharged through lines 77 into the collecting devices 79, where it is cooled and freed of chlorine, and then through line 43 be discharged.

The collected aluminum oxide is freed from the absorbed chlorine gases. It arises in the process a finely divided powder, the grain size of which is uniform and is approximately 0.07 μ.

Claims (5)

. Claims: 5 <> 1. Process for the production of oxides of titanium, aluminum, zirconium or hafnium by exothermic oxidation with oxygen of halides of these metals, which have a low boiling or sublimation point below 350 ° C, preferably below 250 ° C, in a fluidized bed of inert Solid material with a particle size of about 40 to 1000 μ, the resulting oxides being entrained at least for the most part by the gases emerging from the bed and the heating of the reactants takes place solely through the heat released during the reaction and the reactants through several inlet openings from are introduced into the bed below, characterized in that the dimensions of the bed with a minimum diameter of 38 cm and a static height of the bed material of 30 to 90 cm are selected and the flow rate of the gases between 2 to 50 times that for the induction of Required minimum flow rate indigkeit are set in such a way that sufficient heat is stored in the bed in a manner known per se to keep the reaction going, on the other hand the temperature in the bed in a likewise known manner by replacing inert solid material with cooler material to a value below 1200 ⁰ C, preferably below 1100 ⁰ C, regulated and the total increase in oxide on the bed material is kept below 20% of the bed weight by ongoing or recurring cleaning and that the reactants are passed through throttling points before entering the bed, in which in a known manner there is a pressure drop of at least half the size of the pressure drop in the bed. 2. The method according to claim 1, characterized in that at least one of the reactants at a rate sufficient to produce the flow state of the bed is introduced into the bed. 3. The method according to claims 1 and 2, characterized in that one in the bed Gas velocity of at least 8 cm / sec is maintained. 4. The method according to claims 1 to 3, characterized in that by the next the Boundary wall of the bed arranged inlet ports oxygen is supplied. 5. Process according to Claims 1 to 4, characterized in that the temperature control additionally takes place by cooling the fluidized bed. Considered publications:
British Patent No. 761770. Legacy Patents Considered:
German Patent No. 1109 292. For this purpose 2 sheets of drawings 509 718/451 10.65 Q Bundesdruckerei Berlin