Device and method for separating and removing chlorine in titanium chloride white production

Abstract

This invention discloses an apparatus and method for separating and removing chlorine in the production of titanium dioxide using the chloride process. The apparatus includes an external device, a vertically arranged first cylinder, a second cylinder disposed within the first cylinder, and a feed pipe tangentially connected to the upper part of the first cylinder. Both the first and second cylinders are made of conductive materials. The external device is electrically connected to both the first and second cylinders to create a voltage difference between them. The second cylinder has multiple vent holes penetrating its interior and exterior. By providing vent holes and using a tangentially designed feed pipe, this invention allows the primary titanium dioxide product to enter between the first and second cylinders at a relatively high pressure and speed. Under the action of centrifugal force and gravity, gas and solid are separated. Furthermore, by increasing vibration, adding external electrodes, and purging with inert gas, the separation efficiency is greatly improved, and the chlorine content adsorbed on the surface of the titanium dioxide is reduced.

Description

Technical Field

[0001] This invention relates to the field of titanium dioxide production technology via the chloride process, and more particularly to an apparatus and method for separating and removing chlorine in the production of titanium dioxide via the chloride process. Background Technology

[0002] The production principle of titanium dioxide via the chloride process mainly involves the direct oxidation reaction of titanium tetrachloride with oxygen at high temperatures to obtain titanium dioxide and chlorine. Although most of the chlorine is removed through bag filters during the current production process, some chlorine remains adsorbed on the surface of the titanium dioxide, causing a series of quality problems, such as chloride ions entering subsequent production processes leading to decreased pH and excessively high viscosity. Therefore, removing chlorine in its initial gaseous form during the production process is beneficial for improving product quality and reducing subsequent production costs. The separated chlorine can be collected, enriched, and reused, or absorbed through alkaline solutions to reduce its harm to the environment and human health. Existing technology describes cyclone separators that can separate solids and gases, but no similar device has been used to separate residual chlorine in titanium dioxide produced via the chloride process. The challenge lies in the small particle size of titanium dioxide produced via the chloride process (180±20 nm) and the toxicity and corrosiveness of chlorine. Existing hydrocyclones (cyclone separators) can separate solids and gases, but they can usually only separate solids with a particle size greater than 0.2 mm, which cannot meet the separation requirements of raw titanium dioxide.

[0003] Therefore, finding a device or method that can effectively separate chlorine gas from raw titanium dioxide is a technical problem that urgently needs to be solved by those skilled in the art.

[0004] Therefore, existing technologies still need improvement. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an apparatus and method for separating and removing chlorine during the production of titanium dioxide, thereby resolving the technical issues related to chlorine separation in primary titanium dioxide products in the prior art.

[0006] To solve the above-mentioned technical problems, on the one hand, some embodiments of the present invention disclose a device for separating and removing chlorine in the production of titanium dioxide by the chloride process, including external equipment, a vertically arranged first cylinder, a second cylinder arranged inside the first cylinder, and a feed pipe tangentially connected to the upper part of the first cylinder.

[0007] Furthermore, both the first cylinder and the second cylinder are made of conductive materials, and the external device is electrically connected to the first cylinder and the second cylinder respectively, so as to form a voltage difference between the first cylinder and the second cylinder;

[0008] The second cylinder is provided with multiple ventilation holes that penetrate the inside and outside of the second cylinder.

[0009] In some embodiments, the first cylinder includes a feeding section and a discharge section;

[0010] The material discharge section extends downward from the lower end of the feeding section, and its inner diameter gradually decreases; the feeding pipe is connected to the feeding section;

[0011] The second cylinder is arranged concentrically with the first cylinder, and the outer diameter of the second cylinder is the same along the height direction.

[0012] In some embodiments, a vibration pump is also included, the vibration end of which is disposed on the outer wall of the first cylinder.

[0013] In some embodiments, an inert gas storage tank and a recovered gas storage tank are also included, and the lower end of the second cylinder is connected to the inert gas storage tank through a non-conductive lower connecting cylinder.

[0014] The upper end of the second cylinder is connected to the recovered gas storage tank via a non-conductive upper connecting cylinder.

[0015] In some embodiments, the external device includes a first electrode and a second electrode, the first electrode and the second electrode being connected to the first cylinder and the second cylinder, respectively.

[0016] In some embodiments, the first electrode and the second electrode apply positive and negative DC voltages to the first cylinder and the second cylinder, respectively.

[0017] On the other hand, some embodiments of the present invention also disclose a method for separating and removing chlorine in the production of titanium dioxide, which is implemented using the aforementioned apparatus for separating and removing chlorine in the production of titanium dioxide; including:

[0018] The mixture discharged from the material outlet of the oxidation reactor enters the first cylinder tangentially at a predetermined pressure and swirls downward in the gap between the first and second cylinders. The chlorine gas in the mixture enters the interior of the second cylinder through the vent and is discharged from the upper end of the first cylinder. The solid material is discharged from the lower end of the gap between the first and second cylinders under the action of gravity and centrifugal force.

[0019] In some embodiments, inert gas is injected into the second cylinder through an inert gas storage tank connected to the lower end of the second cylinder to assist in the separation of chlorine.

[0020] And / or, by installing a vibration pump on the outer wall of the first cylinder to allow the material attached to the first cylinder to fall smoothly;

[0021] And / or, positive and negative DC voltages applied to the first and second cylinders by external devices to selectively screen and separate charged ions through electrostatic interaction between the first and second cylinders.

[0022] In some embodiments, titanium dioxide adhering to the first and second cylinders is cleaned by reversing the electrodes of the first and second cylinders.

[0023] In some embodiments, the predetermined pressure is 250-350 kPa.

[0024] By adopting the above technical solution, the present invention has at least the following beneficial effects:

[0025] This invention provides an apparatus and method for separating and removing chlorine in the production of titanium dioxide using the chloride process. By incorporating vents and a tangentially designed feed pipe, the initial titanium dioxide product can enter between the first and second cylinders at a relatively high pressure and speed. Under the action of centrifugal force and gravity, gas and solid are separated. Simultaneously, by increasing vibration, adding external electrodes, and purging with inert gas, the separation efficiency can be greatly improved, reducing the chlorine content on the surface of the titanium dioxide powder. This invention removes chlorine in the early stages of production while it is still in the form of chlorine gas, which is beneficial for improving product quality and reducing subsequent production costs. The separated chlorine gas can be collected, enriched, and reused, or absorbed by alkaline solution, reducing its harm to the environment and human health. Furthermore, the titanium dioxide product separated by this apparatus has a more concentrated particle size distribution, further improving product quality. It has broad application prospects in the chloride process titanium dioxide industry. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. 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.

[0027] Figure 1 This is a schematic diagram of a device for separating and removing chlorine in the production of titanium dioxide according to some embodiments of the present invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. First cylinder; 11. Feeding section; 12. Discharge section; 2. Second cylinder; 21. Upper connecting cylinder; 22. Lower connecting cylinder; 3. Feeding pipe; 4. Vibration pump; 5. External equipment; 51. First electrode; 52. Second electrode; 6. Vent hole. Detailed Implementation

[0030] The embodiments of this disclosure will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of this disclosure by way of example, but should not be used to limit the scope of this disclosure. This disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0031] These embodiments are provided to make the disclosure thorough and complete, and to fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​set forth in these embodiments should be interpreted as exemplary only and not as limiting.

[0032] It should be noted that, in the description of this disclosure, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationship, are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0033] Furthermore, the terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. "Vertical" is not strictly vertical, but within the permissible margin of error. "Parallel" is not strictly parallel, but within the permissible margin of error. Terms such as "including" or "contains" mean that the element preceding the word encompasses the element listed after the word, and do not exclude the possibility of encompassing other elements as well.

[0034] It should also be noted that, in the description of this disclosure, unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this disclosure depending on the specific circumstances. When a particular device is described as being located between a first device and a second device, an intermediary device may or may not be present between the particular device and the first or second device.

[0035] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0036] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0037] like Figure 1 As shown in some embodiments of the present invention, a device for separating and removing chlorine in the production of titanium dioxide using the chloride process is disclosed. The device includes an external connection 5, a vertically arranged first cylinder 1, a second cylinder 2 disposed within the first cylinder 1, and a feed pipe 3 tangentially connected to the upper part of the first cylinder 1. Both the first cylinder 1 and the second cylinder 2 are made of conductive material. The external connection 5 is electrically connected to both the first cylinder 1 and the second cylinder 2 to create a voltage difference between them. The second cylinder 2 has multiple vent holes 6 penetrating its interior and exterior. Generally, the material tangentially entering the first cylinder 1 should have sufficient velocity or pressure. During production, this device is directly connected to the upstream oxidation equipment. The material flow velocity from the oxidation equipment is generally 30-35 m / s, and the pressure is approximately 350 kPa. By setting a reasonable pipe length and diameter, the pressure entering the first cylinder 1 can be approximately 300 kPa.

[0038] This embodiment, by incorporating a vent 6 and a tangentially designed feed pipe 3, allows the initial titanium dioxide product to enter between the first cylinder 1 and the second cylinder 2 at a relatively high pressure and speed. Under the influence of centrifugal force and gravity, gas and solid are separated. Furthermore, by increasing vibration, adding external electrodes, and purging with inert gas, the separation efficiency can be significantly improved, reducing the chlorine content on the surface of the titanium dioxide. Removing chlorine in its initial gaseous form during production improves product quality and reduces subsequent production costs. The separated chlorine is either collected, enriched, and reused, or absorbed through alkaline solutions, minimizing its harm to the environment and human health.

[0039] This invention discloses an apparatus for separating and removing chlorine in the production of titanium dioxide. Based on the above embodiments, to achieve smooth feeding and maintain the flow rate and pressure after feeding to obtain sufficient centrifugal force, the first cylinder 1 includes a feeding section 11 and a discharge section 12. The discharge section 12 extends downward from the lower end of the feeding section 11, and its inner diameter gradually decreases. The feeding section 11 is arranged with a constant diameter from top to bottom, so that the velocity and pressure of the material in the feeding section 11 change little. The feeding pipe 3 is connected to the feeding section 11. The second cylinder 2 is arranged concentrically with the first cylinder 1, and the outer diameter of the second cylinder 2 is the same along the height direction. At the same time, as the inner diameter of the lower part of the first cylinder 1 gradually decreases, the material obtains centrifugal force and state similar to a hydrocyclone during the descent. In addition, with the vent holes 6 provided on the cylinder wall of the second cylinder 2, not only can chlorine be effectively separated, but the particle size distribution of the separated titanium dioxide product can also be more concentrated, and the product quality can be further improved.

[0040] This invention discloses an apparatus for separating and removing chlorine in the production of titanium dioxide. Based on the above embodiments, to prevent material from adhering to the inner wall of the first cylinder 1 and causing poor material flow, a vibration pump 4 can be installed outside the first cylinder 1. The vibration end of the vibration pump 4 is located on the outer wall of the first cylinder 1, generally at the lower part of the first cylinder 1, and the vibration frequency is generally set to 20-500 Hz to obtain a better oscillation effect. In this embodiment, to further improve the chlorine removal efficiency, an inert gas storage tank and a recovery gas storage tank can also be provided. Specifically, the lower end of the second cylinder 2 is connected to the inert gas storage tank through a non-conductive lower connecting cylinder 22; the upper end of the second cylinder 2 is connected to the recovery gas storage tank through a non-conductive upper connecting cylinder 21. Inert gas is blown into the lower end of the second cylinder 2 through the inert gas storage tank, creating a slight negative pressure at the vent 6, thereby allowing chlorine to enter the interior of the second cylinder 2 more quickly and in greater quantities through the gap between the first cylinder 1 and the second cylinder 2. Subsequently, as the inert gas moves upward, it enters the recovery gas storage tank. The recovered chlorine and inert gases can be enriched and reused, or absorbed by alkaline solutions to reduce their harm to the environment and human health.

[0041] This invention discloses an apparatus for separating and removing chlorine in the production of titanium dioxide. Building upon the aforementioned embodiments, to achieve a voltage difference between the conductive portions of the first cylinder 1 and the second cylinder 2, thus creating an electrostatic force between them, the external device 5 includes a first electrode 51 and a second electrode 52, respectively connected to the first cylinder 1 and the second cylinder 2. The first electrode 51 and the second electrode 52 apply positive and negative DC voltages to the first cylinder 1 and the second cylinder 2, respectively, selectively screening and separating charged ions through electrostatic interaction. The maximum voltage is generally no more than the safe voltage for the human body (0-36 V), and the voltage can be adjusted according to the equipment's operating conditions. If necessary, the electrodes can be reversed to facilitate the cleaning of titanium dioxide adsorbed on the first cylinder 1 and the second cylinder 2. Furthermore, pressure, temperature, and flow sensors can be installed at each inlet and outlet of the device to facilitate monitoring and adjustment of the device's operation.

[0042] Some embodiments of the present invention also disclose a method for separating and removing chlorine in the production of titanium dioxide, which is implemented using the apparatus for separating and removing chlorine in the production of titanium dioxide as described in the previous embodiments; including: a mixture discharged from the material outlet of the oxidation reactor enters the first cylinder 1 tangentially at a predetermined pressure, and swirls downward in the gap between the first cylinder 1 and the second cylinder 2; chlorine gas in the mixture enters the interior of the second cylinder 2 through the vent 6 and is discharged from the upper end of the first cylinder 1; solid material is discharged from the lower end of the gap between the first cylinder 1 and the second cylinder 2 under the action of gravity and centrifugal force. Generally, inert gas can also be injected into the second cylinder 2 through an inert gas storage tank connected to the lower end of the second cylinder 2 to assist in the separation of chlorine gas; or a vibration pump 4 can be installed on the outer wall of the first cylinder 1 to allow the material attached to the first cylinder 1 to fall smoothly; or positive and negative DC voltages can be applied to the first cylinder 1 and the second cylinder 2 through an external device 5 to selectively screen and separate charged ions through electrostatic interaction between the first cylinder 1 and the second cylinder 2. This embodiment is described using an "or" approach. It should be noted that the above structures are not necessarily used in isolation. They can be used individually in a particular embodiment or together as needed.

[0043] Some embodiments of this invention also disclose a method for separating and removing chlorine in the production of titanium dioxide. Based on the above embodiments, the titanium dioxide powder adhering to the first cylinder 1 and the second cylinder 2 can be cleaned by reversing the electrodes. The electrodes on the first cylinder 1 and the second cylinder 2 reverse instantaneously, and the titanium dioxide powder adsorbed on them receives completely opposite forces instantly, allowing it to easily detach from the cylinder wall. In use, a titanium dioxide-chlorine gas mixture with a certain flow rate enters the first cylinder 1 of the device through the feed pipe 3. Due to the action of centrifugal force and gravity, the solid and gas are separated. The gas flows out through the upper end of the second cylinder 2, and the solid flows out through the lower end of the gap between the first cylinder 1 and the second cylinder 2. An inert gas can be selectively introduced into the lower end of the second cylinder 2 to assist in the separation of chlorine gas. An external device 5 applies positive and negative DC voltages to the first cylinder 1 and the second cylinder 2 respectively, and selectively filters and separates charged ions through electrostatic interaction. If necessary, the electrodes can be reversed to facilitate the cleaning of titanium dioxide powder adsorbed on the hydrocyclone and hollow conduit. The vibration pump 4 acts on the outside of the first cylinder 1 to promote the shedding of titanium dioxide adhering to the inner wall of the hydrocyclone.

[0044] In summary, the apparatus and method for separating and removing chlorine in the production of titanium dioxide using the chloride process disclosed in this invention can directly increase the slurry concentration in post-treatment, thereby releasing production capacity and generating economic benefits. It can reduce the amount of hydrogen peroxide and alkali used in current dechlorination processes, directly reducing production input costs. It can reduce the salt concentration in the subsequent pulping process, further improving product quality and competitiveness. It can reduce the salt concentration in wastewater, reducing wastewater treatment volume and indirectly lowering production costs. It can reduce the environmental harm of the chloride process in titanium dioxide production, making the chloride process more green and environmentally friendly, with broad prospects for widespread application.

[0045] The embodiments of this disclosure have now been described in detail. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0046] While specific embodiments of this disclosure have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this disclosure. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner.

Claims

1. A device for separating and removing chlorine in the production of titanium dioxide using the chloride process, characterized in that, It includes external equipment, a vertically arranged first cylinder, a second cylinder disposed inside the first cylinder, and a feed pipe tangentially connected to the upper part of the first cylinder; Furthermore, both the first cylinder and the second cylinder are made of conductive materials, and the external device is electrically connected to the first cylinder and the second cylinder respectively, so as to form a voltage difference between the first cylinder and the second cylinder; The second cylinder is provided with multiple ventilation holes that penetrate the inside and outside of the second cylinder; It also includes an inert gas storage tank and a recovered gas storage tank. The lower end of the second cylinder is connected to the inert gas storage tank through a non-conductive lower connecting cylinder, and the upper end of the second cylinder is connected to the recovered gas storage tank through a non-conductive upper connecting cylinder.

2. The apparatus for separating and removing chlorine in the production of titanium dioxide according to claim 1, characterized in that, The first cylinder includes a feeding section and a discharge section; The material discharge section extends downward from the lower end of the feeding section, and its inner diameter gradually decreases; the feeding pipe is connected to the feeding section; The second cylinder is arranged concentrically with the first cylinder, and the outer diameter of the second cylinder is the same along the height direction.

3. The apparatus for separating and removing chlorine in the production of titanium dioxide according to claim 1, characterized in that, It also includes a vibration pump, the vibration end of which is disposed on the outer wall of the first cylinder.

4. The apparatus for separating and removing chlorine in the production of titanium dioxide according to claim 1, characterized in that, The external device includes a first electrode and a second electrode, which are respectively connected to the first cylinder and the second cylinder.

5. The apparatus for separating and removing chlorine in the production of titanium dioxide according to claim 4, characterized in that, The first electrode and the second electrode apply positive and negative DC voltages to the first cylinder and the second cylinder, respectively.

6. A method for separating and removing chlorine in the production of titanium dioxide, characterized in that, The process is achieved using any one of the devices described in claims 1-5 for separating and removing chlorine in the production of titanium dioxide; comprising: The mixture discharged from the material outlet of the oxidation reactor enters the first cylinder tangentially at a predetermined pressure and swirls downward in the gap between the first and second cylinders. The chlorine gas in the mixture enters the interior of the second cylinder through the vent and is discharged from the upper end of the first cylinder. The solid material is discharged from the lower end of the gap between the first and second cylinders under the action of gravity and centrifugal force.

7. The method for separating and removing chlorine in the production of titanium dioxide according to claim 6, characterized in that, Inert gas is injected into the second cylinder through an inert gas storage tank connected to the lower end of the second cylinder to assist in the separation of chlorine. And / or, by installing a vibration pump on the outer wall of the first cylinder to allow the material attached to the first cylinder to fall smoothly; And / or, positive and negative DC voltages applied to the first and second cylinders by external devices to selectively screen and separate charged ions through electrostatic interaction between the first and second cylinders.

8. The method for separating and removing chlorine in the production of titanium dioxide according to claim 6, characterized in that, The titanium dioxide adhering to the first and second cylinders is cleaned by reversing the electrodes of the first and second cylinders.

9. The method for separating and removing chlorine in the production of titanium dioxide according to claim 6, characterized in that, The predetermined pressure is 250-350 kPa.

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