Method for removing scars of oxidation reactor for chlorination method titanium dioxide, method for controlling particle size of primary product of chlorination method titanium dioxide and equipment

Abstract

The application provides a method for controlling the particle size of titanium dioxide primary product in a chlorination process, which comprises the following steps: high-temperature O2 enters an oxidation reactor through a combustion chamber, and TiCl4 vapor enters the oxidation reactor through a TiCl4 feeding ring; the high-temperature O2 and the TiCl4 vapor react in a mixing reaction zone of the oxidation reactor to generate TiO2 powder; CsCl particles are sprayed into the oxidation reactor at the rear end of the feeding ring adjacent to the oxidation reactor; at least one magnetic field is applied to the mixing reaction zone and / or a cooling conduit, and the magnetic field parameters are set according to the target particle size of the titanium dioxide primary product. The application also provides a method for removing scars of an oxidation reactor for titanium dioxide in a chlorination process. The application also provides a device for controlling the particle size of titanium dioxide primary product in a chlorination process. The method of the application effectively solves the problem of scarring of the furnace wall from the rear end of the feeding ring to the high-temperature reaction core area of the oxidation reactor, and the average particle size of the titanium dioxide primary product produced reaches 180-260 nm, the purpose of optimizing the particle size distribution is achieved, and thus the quality of the titanium dioxide primary product in the chlorination process can be stabilized.

Description

Technical Field

[0001] This invention relates generally to the field of titanium dioxide production technology via the chloride process, and more specifically, to a method for removing scale from a titanium dioxide oxidation reactor via the chloride process, a method for controlling the particle size of primary titanium dioxide product via the chloride process, and a device for controlling the particle size of primary titanium dioxide product via the chloride process. Background Technology

[0002] There are two main existing processes for producing titanium dioxide: the chlorination process and the sulfuric acid process. Compared with the sulfuric acid process, the chlorination process has the advantages of high automation, advanced technology, and high quality and environmental friendliness, and is therefore gradually becoming the main trend in the titanium dioxide industry.

[0003] In the production of titanium dioxide, TiO2, a product of the TiCl4 gas-phase oxidation reaction, easily deposits on the inner wall of the high-temperature reactor region within the oxidation reactor, gradually forming a scale layer. Existing technologies mostly employ porous gas-shielding devices to control the scaling problem in the high-temperature reaction zone downstream of the feed ring of the oxidation reactor. However, blowing large amounts of cooling gas into the core reaction zone inevitably negatively impacts the quality of the oxidized product. Large gas volumes result in good scaling removal but small and uneven product particle size; small gas volumes result in acceptable product quality but poor scaling removal. Existing salt spraying methods involve injecting NaCl rock salt particles into the rapid cooling section at the end of the reaction zone, achieving both scaling removal and cooling. However, this method fails to protect the high-temperature core reaction zone of the oxidation reactor.

[0004] Furthermore, the initial particle size of titanium dioxide determines the particle size of the finished product. Therefore, controlling the initial particle size is the core key to controlling the type and quality grade of finished titanium dioxide. How to control the particle size and optimize the particle size distribution of titanium dioxide has become an urgent problem to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for removing scale from a titanium dioxide oxidation reactor produced by the chloride process, a method for controlling the particle size of primary titanium dioxide produced by the chloride process, and a device for controlling the particle size of primary titanium dioxide produced by the chloride process.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a method for removing scale from a titanium dioxide oxidation reactor produced by the chloride process, comprising the following steps:

[0008] High-temperature O2 enters the oxidation reactor through the combustion chamber, and TiCl4 vapor enters the oxidation reactor through the TiCl4 feed ring.

[0009] High-temperature O2 reacts with TiCl4 vapor in the mixing reaction zone of the oxidation reactor to produce TiO2 powder;

[0010] CsCl particles are sprayed into the oxidation reactor near the rear end of the feed ring adjacent to the oxidation reactor.

[0011] Furthermore, CsCl particles are uniformly sprayed in a ring shape into the oxidation reactor at a temperature of 1880–2000°C, 10–30 mm from the rear end of the feed ring of the oxidation reactor.

[0012] Furthermore, the flow rate of CsCl particles is 40–50 kg / h, and the particle size of CsCl particles is 2–3 mm.

[0013] This invention also provides a method for controlling the particle size of primary titanium dioxide produced by the chloride process, comprising the following steps:

[0014] High-temperature O2 enters the oxidation reactor through the combustion chamber, and TiCl4 vapor enters the oxidation reactor through the TiCl4 feed ring.

[0015] High-temperature O2 reacts with TiCl4 vapor in the mixing reaction zone of the oxidation reactor to produce TiO2 powder;

[0016] CsCl particles are sprayed into the oxidation reactor near the rear end of the feed ring of the oxidation reactor.

[0017] At least one magnetic field is applied to the mixing reaction zone and / or cooling conduit, and the magnetic field parameters are set according to the target titanium dioxide particle size.

[0018] Furthermore, CsCl particles are uniformly sprayed in a ring shape into the oxidation reactor at a temperature of 1880–2000°C, 10–30 mm from the rear end of the feed ring of the oxidation reactor.

[0019] Furthermore, the flow rate of CsCl particles is 40–50 kg / h, and the particle size of CsCl particles is 2–3 mm.

[0020] Furthermore, the target titanium dioxide primary product has a particle size of 180–260 nm.

[0021] Furthermore, the magnetic field parameters include the length of the control region and the magnetic field strength. The length of the control region is the range from 0.05 m from the rear end of the feed ring of the oxidation reactor to the end of the mixing reaction zone and / or the end of the cooling conduit. The magnetic field strength is 70–90 Wb / m. 2 .

[0022] This invention also provides a device for controlling the particle size of primary titanium dioxide produced by the chloride process, comprising:

[0023] Combustion chamber;

[0024] TiCl4 feed ring;

[0025] An oxidation reactor, comprising an oxidation reactor feed ring and connected to both the combustion chamber and the TiCl4 feed ring;

[0026] A cooling conduit connected to the oxidation reactor;

[0027] A ring-shaped feeding nozzle is positioned near the rear end of the feed ring of the oxidation reactor to spray CsCl particles into the oxidation reactor.

[0028] At least one controllable magnetic field device is disposed on the oxidation reactor and / or the cooling conduit for applying a magnetic field to the mixing reaction zone of the oxidation reactor and / or the cooling conduit, and for setting the magnetic field parameters according to the target titanium dioxide particle size.

[0029] Furthermore, an annular feeding nozzle is positioned 10-30 mm from the rear end of the feed ring of the oxidation reactor to uniformly spray CsCl particles into the oxidation reactor in an annular manner. The magnetic field parameters include the length of the control region and the magnetic field strength. The control region length extends from 0.05 m from the rear end of the feed ring to the end of the mixing reaction zone and / or the end of the cooling conduit. The magnetic field strength is 70–90 Wb / m. 2 .

[0030] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0031] The method of this invention effectively solves the problem of furnace wall scaling from the rear end of the feed ring of the oxidation reactor to the high-temperature reaction core area. Furthermore, the average particle size of the produced titanium dioxide precursor can reach a precisely controllable level of 180–260 nm, achieving the goal of optimizing particle size distribution and thus stabilizing the quality of the titanium dioxide precursor. In addition, the method of this invention is simple to operate, does not use additives, and is therefore low in cost, offering excellent economic benefits. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic flowchart of the descaling method for the titanium dioxide oxidation reactor of the chloride process of the present invention;

[0034] Figure 2 This is a schematic flowchart of the method for controlling the particle size of primary titanium dioxide produced by the chloride process according to the present invention.

[0035] Figure 3This is a schematic diagram of the structure of the device for controlling the particle size of titanium dioxide primary product produced by the chloride process according to the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0037] See Figure 1 and Figure 3 This invention provides a method for removing scale from a titanium dioxide oxidation reactor produced by the chloride process, comprising the following steps:

[0038] High-temperature O2 enters oxidation reactor 3 through combustion chamber 1, and refined TiCl4 steam enters oxidation reactor 3 through TiCl4 feed ring 2;

[0039] High-temperature O2 and refined TiCl4 vapor react in the mixing reaction zone of oxidation reactor 3 to produce TiO2 powder. The reaction temperature is 1880-2000℃.

[0040] CsCl particles are sprayed into the oxidation reactor 3 at the rear end of the feed ring 7 adjacent to the oxidation reactor.

[0041] In a preferred embodiment, CsCl particles are uniformly sprayed in a ring shape into the oxidation reactor 3 at a temperature of 1880–2000°C, located 10–30 mm from the rear end of the feed ring of the oxidation reactor. The flow rate of the CsCl particles is 40–50 kg / h, and the CsCl particles are solid rock salt particles with a particle size of 2–3 mm. After entering the oxidation reactor 3, the CsCl particles burst and vaporize instantly at the high temperature of 1880–2000°C, resulting in a good scouring and scarring effect on the wall surface of the oxidation reactor 3. This is due to the impact of the bursting of solid particles before vaporization and the impact of the gas after vaporization, which effectively scars the wall surface at the rear end of the feed ring of the oxidation reactor.

[0042] See Figure 2 and Figure 3 This invention provides a method for controlling the particle size of primary titanium dioxide produced by the chloride process, comprising the following steps:

[0043] High-temperature O2 enters oxidation reactor 3 through combustion chamber 1, and refined TiCl4 steam enters oxidation reactor 3 through TiCl4 feed ring 2;

[0044] High-temperature O2 and refined TiCl4 vapor react in the mixing reaction zone of oxidation reactor 3 to produce TiO2 powder. The reaction temperature is 1880-2000℃.

[0045] CsCl particles are sprayed into the oxidation reactor 3 at the rear end of the feed ring 7 adjacent to the oxidation reactor.

[0046] At least one magnetic field is applied to the mixing reaction zone and / or cooling conduit 4, and the magnetic field parameters are set according to the target titanium dioxide particle size.

[0047] In a preferred embodiment, CsCl particles are uniformly sprayed in a ring shape into the oxidation reactor 3 at a temperature of 1880–2000°C, located 10–30 mm from the rear end of the feed ring of the oxidation reactor. The flow rate of the CsCl particles is 40–50 kg / h, and the CsCl particles are solid rock salt particles with a particle size of 2–3 mm. After entering the oxidation reactor 3, the CsCl particles burst and vaporize instantly at the high temperature of 1880–2000°C, which has a good scouring and scarring effect on the wall of the oxidation reactor 3. This is due to the impact of the bursting of solid particles before vaporization and the impact of the gas after vaporization, which can scar the wall of the rear end of the feed ring of the oxidation reactor. At the same time, +1 valence Cs ions are dispersed and attached to the newly formed TiO2 particles, making the primary titanium dioxide particles positively charged.

[0048] In a preferred embodiment, the average velocity of the generated TiO2 particles is controlled to be 35–125 m / s using an oxidation system. Those skilled in the art will understand that this velocity is the material flow rate in most prior art oxidation reactors. Due to the application of at least one magnetic field to the mixing reaction zone and / or cooling conduit 4, the TiO2 particles are controlled by the magnetic field to collide, agglomerate, and form multiple uniform TiO2 particles.

[0049] In a preferred embodiment, the target titanium dioxide virgin particle size is 180–260 nm. Magnetic field parameters include the length of the control region of the magnetic field, which is the range from 0.05 m from the rear end of the feed ring of the oxidation reactor to the end of the mixing reaction zone and / or the end of the cooling conduit. Magnetic field parameters also include the magnetic field strength, which is 70–90 Wb / m. 2 Those skilled in the art should understand that the particle size of the target titanium dioxide precursor can be controlled within the range of 180–260 nm by controlling the length of the control region and the magnetic field strength.

[0050] By applying a controllable magnetic field to the mixing reaction zone or cooling conduit of the oxidation reactor, charged ions are attached to the surface of the newly generated TiO2 particles. Due to the Brownian motion of the tiny TiO2 particles in the mixing reaction zone of the oxidation reactor, they collide and aggregate with each other and continue to grow. However, the particles are different in size. The smaller particles move faster under the influence of the magnetic field force and can quickly approach the larger crystal particles. Under the action of high temperature, the particles fuse with each other, which promotes the growth of titanium dioxide crystal particle size and obtains multiple uniform particles. Thus, while improving the particle size, the particle size distribution of the powder is also optimized.

[0051] Those skilled in the art should understand that the object to which the magnetic field is applied, the intensity of the applied magnetic field, and the length of the controlled region of the magnetic field can be flexibly adjusted according to the particle size of the target titanium dioxide precursor. For example, if the target titanium dioxide precursor particle size is 180-210 nm, the magnetic field can be applied only to the high-temperature reaction zone of the oxidation reactor, and then the corresponding magnetic field intensity and the length of the controlled region can be set. Of course, the magnetic field can also be applied to both the oxidation reactor and the cooling conduit simultaneously, and then the corresponding magnetic field intensity and the length of the controlled region can be set. If the target titanium dioxide precursor particle size is 210-260 nm, then the magnetic field needs to be applied to both the high-temperature reaction zone of the oxidation reactor and the cooling conduit simultaneously, and then the corresponding magnetic field intensity and the length of the controlled region can be set.

[0052] like Figure 3 As shown, the present invention also provides a device for controlling the particle size of primary titanium dioxide produced by the chloride process, comprising:

[0053] Combustion chamber 1, high-temperature O2 enters oxidation reactor 3 through combustion chamber 1.

[0054] TiCl4 feed ring: Refined TiCl4 vapor enters oxidation reactor 3 via TiCl4 feed ring 2.

[0055] The oxidation reactor 3 includes an oxidation reactor feed ring 7, which is connected to the combustion chamber 1 and the TiCl4 feed ring 2, respectively.

[0056] Cooling conduit 4 is connected to oxidation reactor 3.

[0057] An annular feeding nozzle 5 is positioned adjacent to the rear end of the feed ring of the oxidation reactor and is used to spray CsCl particles into the oxidation reactor 3. In a preferred embodiment, the annular feeding nozzle 5 is positioned 10-30 mm from the rear end of the feed ring of the oxidation reactor and is used to uniformly spray CsCl particles into the oxidation reactor 3 in an annular manner.

[0058] At least one controllable magnetic field device 6 is disposed on the oxidation reactor 3 and / or cooling conduit 4, for applying a magnetic field to the mixing reaction zone of the oxidation reactor 3 and / or the cooling conduit 4, and for setting magnetic field parameters according to the target titanium dioxide particle size. In a preferred embodiment, the magnetic field parameters include the length of the control region of the magnetic field and the magnetic field strength. The length of the control region is the range from 0.05 m from the rear end of the feed ring of the oxidation reactor to the end of the mixing reaction zone and / or the end of the cooling conduit, and the magnetic field strength is 70–90 Wb / m. 2 As needed, multiple controllable magnetic field devices can be set. For example, in this embodiment, four controllable magnetic field devices 6 are set on the oxidation reactor 3 and two controllable magnetic field devices 6 are set on the cooling conduit 4.

[0059] The following combination Figure 3 Several embodiments based on the above concept are further described. For example... Figure 3 As shown, oxidation reactor 3 is connected to cooling conduit 4 at point A. Point O is 0.05m from the rear end of the feed ring 7 of oxidation reactor, point A is 0.9m from the rear end of the feed ring 7 (i.e., the total length of the high-temperature reaction zone from the feed ring 7 to the tail of oxidation reactor 3), point B is 17m from the rear end of the feed ring 7, point C is 20m from the rear end of the feed ring 7, and point D is 25m from the rear end of the feed ring 7. The length of the control area of ​​the magnetic field applied to oxidation reactor 3 and / or cooling conduit 4 varies depending on the target titanium dioxide particle size. Figure 3 The length ranges between the ODs shown vary.

[0060] Those skilled in the art should understand that, due to the presence of CsCl ions in... Figure 3 The particles, located between point O and the rear end of the feed ring 7 of the oxidation reactor, are not fully dispersed and cannot be uniformly mixed with TiO2 particles. Therefore, they fail to apply a positive charge to the TiO2 particles and are thus not properly dispersed. Figure 3 A magnetic field is applied to the length range between point O and the rear end of the feed ring 7 of the oxidation reactor.

[0061] Those skilled in the art should understand that, depending on the specifications of the oxidation reactor and cooling conduit, the applied magnetic field strength and the corresponding length of the magnetic field control area can be adjusted according to the actual situation.

[0062] Example 1

[0063] In this embodiment, the target titanium dioxide raw material to be produced is required to have a particle size of approximately 210 nm. Therefore, a magnetic field can be applied to... Figure 3 Within the length range between OB shown, where point O is 0.05m from the rear end of the feed ring of the oxidation reactor and point B is 17m from the rear end of the feed ring of the oxidation reactor, the magnetic field strength is 77Wb / m. 2 .

[0064] High-temperature O2 enters the oxidation reactor through the combustion chamber, while refined TiCl4 vapor enters the reactor through the TiCl4 feed ring. The high-temperature O2 and refined TiCl4 vapor react at 1880℃ in the mixing reaction zone of the oxidation reactor to generate TiO2 powder. The average velocity of the generated TiO2 powder within the system is controlled by the oxidation system to be 117 m / s. At a distance of 25 mm from the rear end of the feed ring of the oxidation reactor, CsCl particles are uniformly sprayed into the reactor in a ring pattern. The flow rate of the CsCl particles is 40 kg / h, and the particle size is 3 mm. Under the control of a magnetic field, the TiO2 particles collide and agglomerate, forming multiple uniform TiO2 particles. The actual measured average particle size of the initial titanium dioxide product is 210 ± 10 nm.

[0065] Example 2

[0066] In this embodiment, the target titanium dioxide raw material to be produced requires a particle size of approximately 180 nm. Therefore, the magnetic field can be applied only to the mixing reaction zone of the oxidation reactor. Specifically, the magnetic field is applied to... Figure 3 Within the length range between OA shown, where point O is 0.05m from the rear end of the feed ring of the oxidation reactor and point A is 0.9m from the rear end of the feed ring of the oxidation reactor, the magnetic field strength is 90Wb / m. 2 .

[0067] High-temperature O2 enters the oxidation reactor through the combustion chamber, while refined TiCl4 vapor enters the reactor through the TiCl4 feed ring. The high-temperature O2 and refined TiCl4 vapor react at 1880℃ in the mixing reaction zone of the oxidation reactor to generate TiO2 powder. The average velocity of the generated TiO2 powder within the system is controlled by the oxidation system to be 117 m / s. CsCl particles are uniformly sprayed into the oxidation reactor in a ring pattern 10 mm from the rear end of the feed ring. The flow rate of the CsCl particles is 50 kg / h, and the particle size is 2 mm. Under the control of a magnetic field, the TiO2 particles collide and agglomerate to form multiple uniform TiO2 particles. The actual measured average particle size of the initial titanium dioxide product is 180 ± 10 nm.

[0068] Example 3

[0069] In this embodiment, the target titanium dioxide raw material to be produced is required to have a particle size of approximately 230 nm. Therefore, a magnetic field can be applied to... Figure 3 Within the length range between points O and C shown, where point O is 0.05 m from the rear end of the feed ring of the oxidation reactor and point C is 20 m from the rear end of the feed ring of the oxidation reactor, the magnetic field strength is 80 Wb / m. 2 .

[0070] High-temperature O2 enters the oxidation reactor through the combustion chamber, while refined TiCl4 vapor enters the reactor through the TiCl4 feed ring. The high-temperature O2 and refined TiCl4 vapor react at 1880℃ in the mixing reaction zone of the oxidation reactor to generate TiO2 powder. The average velocity of the generated TiO2 powder within the system is controlled by the oxidation system to be 117 m / s. CsCl particles are uniformly sprayed into the oxidation reactor in a ring pattern 30 mm from the rear end of the feed ring. The flow rate of the CsCl particles is 45 kg / h, and the particle size is 3 mm. Under the control of a magnetic field, the TiO2 particles collide and agglomerate, forming multiple uniform TiO2 particles. The actual measured average particle size of the initial titanium dioxide product is 230 ± 10 nm.

[0071] Example 4

[0072] In this embodiment, the target titanium dioxide raw material to be produced is required to have a particle size of approximately 260 nm. Therefore, a magnetic field can be applied to... Figure 3 Within the length range between OD shown, where point O is 0.05m from the rear end of the feed ring of the oxidation reactor and point D is 25m from the rear end of the feed ring of the oxidation reactor, the magnetic field strength is 70Wb / m. 2 .

[0073] High-temperature O2 enters the oxidation reactor via the combustion chamber, while refined TiCl4 vapor enters the reactor via the TiCl4 feed ring. The high-temperature O2 and refined TiCl4 vapor react at 1880℃ in the mixing reaction zone of the oxidation reactor to generate TiO2 powder. The average velocity of the generated TiO2 powder within the system is controlled by the oxidation system to be 117 m / s. CsCl particles are uniformly sprayed into the oxidation reactor in a ring pattern 15 mm from the rear end of the feed ring. The flow rate of the CsCl particles is 45 kg / h, and the particle size is 2 mm. Under the control of a magnetic field, the TiO2 particles collide and agglomerate, forming multiple uniform TiO2 particles. The actual measured average particle size of the initial titanium dioxide product is 260 ± 10 nm.

[0074] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0075] It should be noted that the components or steps in the above embodiments can be interchanged, substituted, added, or deleted. Therefore, the combinations formed by these reasonable permutations and transformations should also fall within the protection scope of this invention, and the protection scope of this invention should not be limited to the above embodiments.

[0076] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for removing scale from a titanium dioxide oxidation reactor using the chloride process, characterized in that, Includes the following steps: High-temperature O2 enters the oxidation reactor through the combustion chamber, and TiCl4 vapor enters the oxidation reactor through the TiCl4 feed ring. High-temperature O2 reacts with TiCl4 vapor in the mixing reaction zone of the oxidation reactor to produce TiO2 powder; At a distance of 10-30 mm from the rear end of the feed ring of the oxidation reactor, CsCl particles are uniformly sprayed in a ring into the oxidation reactor at a temperature of 1880~2000℃, with a flow rate of 40~50 kg / h.

2. The method according to claim 1, characterized in that, The CsCl particles have a particle size of 2~3 mm.

3. A method for controlling the particle size of primary titanium dioxide produced by the chloride process, characterized in that, Includes the following steps: High-temperature O2 enters the oxidation reactor through the combustion chamber, and TiCl4 vapor enters the oxidation reactor through the TiCl4 feed ring. High-temperature O2 reacts with TiCl4 vapor in the mixing reaction zone of the oxidation reactor to produce TiO2 powder; At a distance of 10-30 mm from the rear end of the feed ring of the oxidation reactor, CsCl particles are uniformly sprayed into the oxidation reactor at a temperature of 1880~2000℃ in a ring. The flow rate of CsCl particles is 40~50 kg / h. The +1 valence Cs ions are dispersed and attached to the TiO2 particles, thereby applying a positive charge to the TiO2 particles. At least one magnetic field is applied to the mixing reaction zone and / or cooling conduit, and the magnetic field parameters are set according to the target titanium dioxide particle size. The magnetic field parameters include the length of the control region of the magnetic field and the magnetic field strength. The length of the control region of the magnetic field is the range from 0.05 m from the rear end of the feed ring of the oxidation reactor to the end of the mixing reaction zone and / or the end of the cooling conduit, and the magnetic field strength is 70~90 Wb / m. 2 TiO2 particles are controlled by a magnetic field to collide and cluster, forming multiple uniform TiO2 particles.

4. The method according to claim 3, characterized in that, The CsCl particles have a particle size of 2~3 mm.

5. The method according to claim 3, characterized in that, The target titanium dioxide primary product has a particle size of 180~260nm.

6. A device for controlling the particle size of primary titanium dioxide produced by the chloride process, characterized in that, include: Combustion chamber; TiCl4 feed ring; An oxidation reactor includes an oxidation reactor feed ring, which is connected to the combustion chamber and the TiCl4 feed ring, respectively. High-temperature O2 and TiCl4 vapor react in the mixing reaction zone of the oxidation reactor to generate TiO2 powder. A cooling conduit connected to the oxidation reactor; A ring-shaped feeding spray gun is set 10-30 mm away from the rear end of the feed ring of the oxidation reactor. It is used to uniformly spray CsCl particles into the oxidation reactor at a temperature of 1880~2000℃ in a ring. The +1 valence Cs ions are dispersed and attached to the TiO2 particles, thereby applying a positive charge to the TiO2 particles. At least one controllable magnetic field device is disposed on the oxidation reactor and / or the cooling conduit for applying a magnetic field to the mixing reaction zone of the oxidation reactor and / or the cooling conduit. The magnetic field parameters are set according to the target titanium dioxide particle size, including the length of the control region and the magnetic field strength. The control region length is the range from 0.05 m from the rear end of the feed ring of the oxidation reactor to the end of the mixing reaction zone and / or the end of the cooling conduit, and the magnetic field strength is 70~90 Wb / m. 2 In this process, TiO2 particles are controlled by a magnetic field to collide and cluster, forming multiple uniform TiO2 particles.

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