JP3091372B2 - Solid particle powder treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stirring a harmful component gas from a solid particle powder of titanium dioxide containing a halogen gas by mixing metal particles and metal oxides containing the harmful component gas with a countercurrent solid-gas contactor. The present invention relates to a method for efficiently removing a harmful component gas using a fluidized bed and a method for densifying the solid particle powder subjected to the removal treatment.

[0002]

BACKGROUND OF THE INVENTION In general, solid particles such as metal particles and metal oxide particles produced by a gas phase reaction are produced as by-products by a solid-gas separation and collection device such as a cyclone or a bag filter. Separated and collected from gas fluids such as gas, unreacted gas and carrier gas.

However, harmful component gases such as by-product gas and unreacted gas generated in the gas phase reaction adhere to the surfaces of the separated and collected solid particles, and are absorbed and absorbed in the solid particle powder. Therefore, it is extremely difficult to perform solid-gas separation of substantially all of the harmful components.

By the way, for example, a gas-phase synthesis method in which titanium halide is oxidized in a gas phase to produce titanium dioxide particle powder is different from a so-called sulfuric acid method which has been practiced for a long time. It is possible to mass-produce titanium dioxide pigments with high whiteness and excellent dispersibility in a relatively small apparatus configuration, and it is advantageous in terms of production efficiency and cost, and furthermore, what is called by-product produced by the process In recent years, industrial implementation has been rapidly spreading due to the small amount of waste generated.

For example, in the above-mentioned vapor phase synthesis method, titanium dioxide fine particle powder produced by vapor phase oxidation of titanium tetrachloride produces irritating odorous chlorine gas or unreacted titanium tetrachloride gas by-produced. Harmful component gas is separated and collected by cyclone and bag filter. In the separated and collected titanium dioxide fine powder, about 65 to 75% (based on the volume of the titanium dioxide fine powder-containing gas) of harmful component gases of chlorine-based impurities remains. Pigment properties such as dispersibility are significantly impaired in the system and are contraindicated due to corrosiveness and environmental pollution, and various removal methods have been proposed.

[0006] For example, the titanium dioxide fine particles collected by solid-gas separation and collection as described above are put into water to form a slurry, which is neutralized with an alkali such as sodium hydroxide or ammonia and remains. Chlorine impurities are removed by a wet system. However, in the case of performing wet processing as described above, after the processing, filtration, washing, drying, and further require processing such as pulverization, not only increases the cost,
Secondary agglomeration and the like are likely to occur during the treatment process. In particular, when the titanium dioxide fine particles separated and collected are not subjected to surface finishing treatment in the next step, for example, when the slurry is transported to a remote location and the surface finishing treatment is performed in that location, a large amount of the titanium dioxide fine particles are added together with the corrosiveness of the transport container. The cost burden for transporting the aqueous medium is large, and filtration, washing, drying,
When transporting to a remote location after processing such as crushing,
At the time of the surface finishing treatment, it is necessary to re-slurry and perform the surface finishing treatment, and thereafter, it is necessary to repeat processes such as filtration, washing, drying, and pulverization, which further increases the burden on costs.

On the other hand, a method of removing the titanium dioxide fine particle powder containing a harmful component gas of chlorine-based impurities collected by solid-gas separation by a so-called dry system includes, for example, (a) a gas phase reaction. A method of heat-treating the generated titanium dioxide fine particle powder at 500 to 800 ° C., (b) a method of reacting steam or a gas such as boric acid in the treatment of (a), (c) a method of (a) Has proposed a method of injecting a gas fluid such as water vapor or oxygen at a sonic or supersonic speed so as to form a cross flow with respect to the flow of the gas fluid containing titanium dioxide fine particle powder. However, in the case of the above-described methods, the removal of harmful component gases is not sufficient, or a large amount of cleaning gas is required, so that it is difficult to reuse by-product gas. In addition to the increase in energy cost, fine particle powder, particle growth, or sintering and coarsening or pigment properties are easily damaged, furthermore, when performing the steam treatment However, none of these methods have yet been satisfied, for example, the generated hydrogen chloride gas causes corrosion of equipment, and there is a strong demand for improvement.

[0008]

Means for Solving the Problems The inventors of the present invention have been working on a solid-gas separation / collection device which separates and collects a solid-particle-containing gaseous fluid containing solid particle powder. After conducting various studies with the aim of providing a method capable of efficiently removing harmful component gases from fine particle powders with relatively simple processing means, and industrially advantageously removing substantially all of them, solid- The solid particle powder remaining with the harmful component gas separated and collected by the gas separation trap is first washed by replacing the harmful component gas with a relatively small amount of inert gas that does not hinder the reuse of by-product gas. After removing most harmful component gases,
Then, in a fluidized bed equipped with a stirring mechanism, the remaining harmful component gas which has been occluded is discharged and removed, thereby causing no channeling or clogging of the solid particles, and harmful to industrial advantage by relatively simple means. Transfer, storage, and packaging of fine solid particle powder from which harmful component gases have been removed by being able to wash and remove substantially the majority of component gases, and then performing a densification process subsequent to the process. In addition, the workability of handling the powder in transportation and the like is remarkably easy, and in particular, the continuous system such as the removal processing of the harmful component gas of the solid particle fine powder and the removal and transfer of the processed fine powder becomes easy, and the bulk transportation work is also facilitated. The present inventors have found that the present invention can be made extremely suitable in terms of efficiency, safety, and cost reduction, and have completed the present invention.

That is, according to the present invention, (1) a solid particle powder containing a harmful component gas is introduced into a solid-gas contactor and brought into countercurrent contact with an inert gas stream to release the harmful component gas, and then stirred. (2) a method for treating solid particle powder, which comprises introducing a fluidized bed to remove residual harmful component gases;
The solid particle powder containing the harmful component gas is introduced into a solid-gas contactor and brought into countercurrent contact with the inert gas stream to release the harmful component gas, and then introduced into the stirred fluidized bed to remove the residual harmful component gas. A method for treating solid particle powder, which comprises removing and then subjecting the treated solid particle powder to high-density treatment; (3) titanium dioxide obtained by subjecting the solid particle powder to gas-phase oxidation of titanium halide 3. The method for treating the solid particle powder according to the above item 1 or 2, which is a particle powder; (4) the method for treating the solid particle powder, wherein the titanium halide is titanium tetrachloride; 3. The method for treating a solid powder according to the above item 1 or 2, wherein the gas is a halogen gas;
(6) The method for treating solid powder according to the preceding item 5, wherein the halogen gas is chlorine gas. (7) The inert gas flow in the solid-gas contactor has a blowing speed of 5 to 30 m / sec and a superficial velocity of 1
The method for treating solid particle powder according to the above item 1 or 2, wherein (8) the fluidizing gas velocity of the stirred fluidized bed is 5 to 10 cm / sec.
30 cm / sec. (1) The method for treating solid particle powder according to the above (1) or (2), wherein (9) the speed of the stirring blade in the stirred fluidized bed is 1 to 5 seconds at an interval of passing the same point at the peripheral end. (10) The method for treating solid particle powder according to item 9, wherein the stirring blade has a vertical shape, (11)
Before bulk density is increased to 0.8 g / cm ³ or more 2
The method for treating solid particle powder in item (12),
The method for treating solid particles according to the above item 2, which is performed by a pressure roll molding machine, and the method (13), wherein the densification treatment is performed when the roll compression load of the pressure roll molding machine is 0.5 to 4 ton / cm ² or more. A method for treating solid particle powder according to item 2.

The present invention can be applied to a process for removing harmful component gases contained in solid particles such as general metal particles, metal oxide particles, metal nitride particles, and metal carbide particles obtained by a gas phase reaction. However, in particular, such as producing solid particles by a gas phase reaction system in which harmful halogen gas such as chlorine-based impurities is produced as by-products, for example, producing titanium dioxide fine powder by reacting titanium tetrachloride in a gas phase. It is particularly suitable when silicon tetrachloride is subjected to a gas phase reaction to produce fine particles of silicon dioxide.

In applying the present invention, a gas fluid containing solid particles generated by various gas-phase reactions is introduced into a solid-gas separator to separate the solid particles from a gas. Solid
Examples of the gas separator include various dry separators generally used in the powder industry, for example, a centrifugal separator such as a cyclone, a filter separator such as a bag filter, and an electrostatic separator such as an electric dust collector. Can be

In order to treat the fine particles of harmful component gas-containing solid particles separated and collected from the gas fluid by the solid-gas separator as described above, various modes can be applied. Hereinafter, description will be given based on FIG. 1 showing an example of an apparatus configuration for carrying out the method of the present invention.

[0013] The fine solid particles containing harmful component gases separated and collected by the solid-gas separator 1 are first introduced into the descending tubular countercurrent solid-gas contactor 2 from the bottom of 1. On the other hand, an inert gas is introduced from the bottom of the solid particles 2, and the harmful component gas contained in the fine particles of the solid particles is replaced by the solid particles coming into contact with the upward flow of the inert gas while descending the solid particles 2. Washed. The inert gas stream is desirably as small as possible so that the recycling of by-product gas is not hindered,
The flow velocity is about 5 to 30 m / sec and the superficial velocity is about 1 to 10 cm / sec. When the temperature is lower than the above range, the replacement cleaning of the harmful component gas is not sufficiently performed.On the other hand, the reuse of the by-product gas which is higher than the range is easily hindered, and the extraction and transfer of a desired amount of the fine solid particle powder is impaired. Or When the gas-phase reaction system is operated in a high-pressure system, the pressure is reduced to the atmospheric pressure while repeating the opening and closing operations of the valve during the extraction and transfer of the fine solid particles. The type of solid particles and gas phase reaction system, the type of harmful component gas, the configuration and size of the device, etc., cannot be described unconditionally, but by the above treatment, about 90 to 90% of the harmful component gas contained in the solid particles to be treated. About 96% can be replaced and removed.

The solid fine powder treated with the inert gas flow as described above is then introduced into a fluidized bed 8 equipped with a stirring mechanism, and gas is blown from the bottom of the other 8 through a porous plate 10. The harmful component gas adhering to the surface of the solid particles or occluded in the particle gap can be removed by gas washing extremely efficiently by fluidizing and forced shearing action by the stirrer. . Various types of blowing gas can be used, and for example, air, oxygen, nitrogen gas and the like can be used. The fluidization speed of the stirring fluidized bed and the speed of the stirring blade are preferably about 5 to 30 cm / sec, respectively, and the peripheral speed is preferably about 1 to 5 seconds (interval passing through the same point). The shape of the stirring blade may be of various types, but is preferably such that the solid particles are sheared in the vertical direction as much as possible, and various types of vertical type are preferable. If the fluidization speed is lower than the above range, the desired removal effect of the harmful component gas will not be obtained. On the other hand, if the fluidization speed is higher than the above range, so-called piston flow will be caused, and uniformity of the fluidized bed will be impaired and efficient gas cleaning will be performed. No effect.

The solid particles containing the residual harmful component gas are as follows:
It is supplied continuously or intermittently from the upper or side portion of the stirred fluidized bed 8 and is discharged after being mixed and contacted with the cleaning gas for a predetermined time. Since the exhaust gas contains harmful component gas, it is introduced into an absorption facility and discharged after harmless treatment.

In the present invention, the solid particle fine powder from which the residual harmful component gas has been removed in the stirred fluidized bed as described above is further densified to increase the bulk density and transfer the powder. In addition to facilitating handling workability in packaging, storage, transportation, and the like, it is possible to further enhance the industrial advantage in terms of cost. The above-mentioned densification treatment can be performed by various methods. For example, by increasing the bulk density to 0.8 g / cm ³ or more using a pressure roll type compression molding machine, the flake-like powder is easily melted. Granules can be obtained. This has good handling operability and can easily be used as an excellent suspension in an aqueous slurry.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described with reference to FIG.
In the step of producing a titanium dioxide pigment by a gas phase oxidation reaction of titanium tetrachloride, the reaction gas A is separated into solid particles and by-product gas B by the solid-gas separation device 1. A countercurrent solid-gas contactor 2 is connected to the lower part of the solid-gas separation device 1 to make the solid particles containing the chlorine gas component and the inert gas come into countercurrent contact to roughly replace the chlorine gas. This contactor has an inner diameter of 30 cm and a length of 2 m. The apparent descent speed of the solid particles is 1-5 cm / sec.
In the lower part of the contactor, 16 holes each having a diameter of 4 mm were opened in the lower tube wall, and inert gas C was sprayed on the solid particles at a speed of 5 to 20 cm / sec.
The chlorine gas is roughly replaced, including the upward flow. At this time 700,000p
The chlorine gas concentration at the inlet of pm is removed up to about 30,000 ppm. Here, the removal rate is 90% or more. When the oxidation reaction is performed in a high-pressure system, the pressure-reducing container 4 is a device that shuts off the reaction system and lowers the pressure to the atmospheric pressure for the next operation. The operation is performed by opening and closing the valves 3, 5, and 6, in the order of closing the valves 5, 6 closed-3 open-3 closed-6 open-6 closed-5 open-5 closed as follows. The size of the decompression vessel is determined by the size of the stirred fluidized bed and the method of supplying solid particles. Since the gas exhausted at the time of pressure reduction contains chlorine gas, it is subjected to absorption treatment in the absorption tower 12. The next stirred fluidized bed has an inner diameter of 500 mm and a height of 2,50
It is made of 0 mm transparent PVC, and the lower dispersing plate has holes of 2 mm diameter with a pitch of 12 mm (opening ratio 2.5%). Stirrer airfoil is portal type, outer diameter is 485mm, height is 500mm
Are two blades having a wing span of 75 mm and rotate at 5 to 30 rotations / minute. Set the stationary layer height of the solid particles to 500 to 1000 mm,
When the solid particles are fluidized at a superficial velocity of 5 to 30 cm / sec by using air as the fluid gas D, the chlorine gas concentration can be adjusted to 0.05 at a residence time of 20 to 150 seconds without any trouble in handling the solid.
It can be removed to below ppm. Next, the solid particles from which the chlorine gas has been removed are supplied to a general pressurized roll type compressor 11, where the operating pressure is 0.5 to 4 without adding a binder.
The bulk density of the solid particles is 0.8 g / cm ² or more at ton / cm ² , and the solid particles are taken out as an intermediate product.

[0018]

According to the present invention, solid particles such as metal particles and metal oxides containing harmful gases are separated by a solid-gas separator, and the solid particles are inertized by using a countercurrent solid-gas contactor. The harmful gas is roughly replaced with a gas, and the solid particles are washed. Next, using a fluidized bed with a vertical stirrer to form a uniform and stable fluidized bed, a method for removing harmful gas adhering to the solid particles, wherein the metal particles containing the harmful gas, metal oxides and the like The harmful gas adhering to the solid particles can be removed to a concentration that does not hinder handling. Furthermore, by raising the bulk density of the solid particles using a pressure roll molding machine, it is possible to take out the solid particles as dry powder that is easy to handle. This is due to equipment corrosion due to residual harmful component gases,
For example, it is a compact solid particle powder with a stable bulk density that can eliminate physical property impairment such as pigment properties, and can be used for bulk transportation to remote places, improvement of productivity in finishing and processing at such places, and high productivity. It is industrially very useful for quality improvement.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an example of a configuration of a processing apparatus suitable for carrying out a method for processing solid particle powder of the present invention.

[Explanation of symbols]

 Reference Signs List A Gas-phase reaction gas (solid-containing particles) B By-product gas C Inert gas D Flowing gas 1 Solid-gas separator 2 Countercurrent solid-gas contactor 3,5,6 Valve 4 Decompression container 7 Quantitative supply device 8 Stirring Fluidized bed 9 Stirrer blade 10 Dispersion plate 11 Pressure roll compression molding machine 12 Absorption tower

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-294945 (JP, A) JP-A-53-73474 (JP, A) JP-A-64-4221 (JP, A) 186512 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B01J 8/00-8/46

Claims (13)

(57) [Claims] Claims: 1. A solid particle powder containing a harmful component gas,
It is introduced into a solid-gas contactor and brought into countercurrent contact with an inert gas stream to release harmful component gases, and then introduced into a stirred fluidized bed.
A method for treating solid particle powder, wherein a residual harmful component gas is released by stirring and contact with a fluidizing gas . 2. A solid particle powder containing a harmful component gas,
It is introduced into a solid-gas contactor and brought into countercurrent contact with an inert gas stream to release harmful component gases, and then introduced into a stirred fluidized bed.
A method for treating solid particle powder, comprising releasing residual harmful component gas by stirring and contacting with a fluidizing gas, and thereafter subjecting the treated solid particle powder to a high-density treatment. 3. The titanium dioxide particle powder obtained by subjecting a titanium halide to gas-phase oxidation in a solid state.
Or 2) the method for treating solid particle powder. 4. The method according to claim 3, wherein the titanium halide is titanium tetrachloride. 5. The method for treating solid particle powder according to claim 1, wherein the harmful component gas is a halogen gas. 6. The method according to claim 5, wherein the halogen gas is chlorine gas.
The method for treating solid particle powders. 7. The blowing speed of the inert gas stream in the solid-gas contactor is 5 to 30 m / sec, and the superficial velocity is 1 to 10 cm.
3. The method for treating solid particle powder according to claim 1 or 2, wherein 8. The fluidized gas velocity of the stirred fluidized bed is 5 to 30.
The method for treating solid particle powder according to claim 1 or 2, wherein the rate is cm / sec. 9. The method for treating solid particle powder according to claim 1, wherein the speed of the stirring blades in the stirred fluidized bed is 1 to 5 seconds at an interval passing through the same point at the peripheral end. 10. The method according to claim 9, wherein the stirring blade has a vertical shape. 11. The method of claim 2, wherein the bulk density is increased to 0.8 g / cm ³ or more. 12. The method for treating solid particle powder according to claim 2, wherein the densification treatment is performed by a pressure roll molding machine. 13. The method for treating solid particle powder according to claim ² , wherein the densification treatment is performed at a roll compression load of a pressure roll molding machine of 0.5 to ⁴ ton / cm ² .