Titanium tetrachloride pretreatment system and pretreatment method

Abstract

The invention discloses a titanium tetrachloride pretreatment system and pretreatment method. The titanium tetrachloride pretreatment system comprises a feeding unit, an alkali washing unit, a cooling unit and a settling separation unit which are connected in sequence, the feeding unit is used for conveying titanium tetrachloride mixed gas obtained by a chlorination method to the alkali washing unit so as to convert aluminum trichloride in titanium tetrachloride into aluminum oxide; the cooling unit is used for cooling the titanium tetrachloride mixed gas subjected to alkali washing to obtain titanium tetrachloride liquid; the settling separation unit is used for settling the titanium tetrachloride liquid to obtain upper clear liquid and lower slurry, and the upper clear liquid is a titanium tetrachloride primary product. The treatment mode provided by the invention is more efficient and economical, and is especially suitable for treating the high-temperature titanium tetrachloride mixed gas. By optimizing the spraying process and controlling the concentration of the alkali liquor, the impurity content in the crude titanium tetrachloride produced by the chlorination method can be effectively reduced in a lower alkali liquor concentration and temperature range and shorter contact time, and the treatment efficiency is high.

Description

Technical Field

[0001] The invention relates to the technical field of titanium tetrachloride production, and more specifically to a titanium tetrachloride pretreatment system and a pretreatment method. Background Art

[0002] In the production process of titanium tetrachloride, titanium-rich material containing titanium dioxide (TiO2) is the main raw material. When the titanium-rich material comes into contact with chlorine in a chlorination furnace, a chlorination reaction occurs to generate a mixed gas mainly containing impurities such as gaseous titanium tetrachloride (TiCl4), aluminum trichloride, ferrous chloride, ferric chloride, titanium slag and coke fine powder. However, the titanium-rich material inevitably contains impurities such as aluminum, which will also react with chlorine to generate by-products such as aluminum chloride (AlCl3) and mix into the titanium tetrachloride mixed gas. Subsequently, the titanium tetrachloride mixed gas is subjected to dust collection and condensation treatment to finally obtain crude titanium tetrachloride. Because more impurity components are mixed into the crude titanium tetrachloride, this undoubtedly increases the difficulty and load of removing impurities in the subsequent refining and purification process. The Chinese patent application number 201410420827.8 discloses a method for removing impurities from crude titanium tetrachloride using alkali solution, but the object of treatment is a crude titanium tetrachloride gas-liquid mixture or liquid, and is not suitable for a mixed gas mainly composed of titanium tetrachloride (TiCl4) discharged from a chlorination furnace. At the same time, the gas temperature and the concentration of the alkali solution used are relatively high, with a temperature of 400°C-550°C and an alkali solution concentration of 30%-60%. In addition, the contact time between the alkali solution and the crude titanium tetrachloride is 1-20 minutes. The Chinese patent application number 202220486547.7 discloses a tail gas treatment device in the process of producing titanium tetrachloride by molten salt chlorination, but the object of treatment is the tail gas generated in the titanium tetrachloride production process, and salt water is generated during the treatment process and needs to be discharged. Summary of the invention

[0003] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a titanium tetrachloride pretreatment system and a pretreatment method for pretreating titanium tetrachloride mixed gas produced by chlorination reaction, which can effectively improve the quality of crude titanium tetrachloride.

[0004] To achieve the above object, the technical solution of the present invention is as follows:

[0005] A titanium tetrachloride pretreatment system comprises a feeding unit, an alkali washing unit, a cooling unit and a sedimentation separation unit which are connected in sequence; the feeding unit is used to convey the titanium tetrachloride mixed gas obtained by a chlorination process to the alkali washing unit; the alkali washing unit is used to perform alkali washing on the titanium tetrachloride mixed gas to convert aluminum trichloride in the titanium tetrachloride into aluminum trioxide; the cooling unit is used to cool the titanium tetrachloride mixed gas after alkali washing and obtain titanium tetrachloride liquid; the sedimentation separation unit is used to sediment the titanium tetrachloride liquid to obtain an upper clear liquid and a lower slurry, wherein the upper clear liquid is a crude titanium tetrachloride product and the lower slurry is treated separately.

[0006] Optionally, the chlorination method includes using a molten salt chlorination furnace or a boiling chlorination furnace.

[0007] Optionally, the titanium tetrachloride mixed gas includes gaseous titanium tetrachloride, aluminum trichloride, ferrous chloride, ferric chloride, titanium slag and coke fine powder.

[0008] Optionally, the temperature of the titanium tetrachloride mixed gas is 350°C to 550°C.

[0009] Optionally, the feeding unit comprises utilizing the negative pressure formed by the exhaust fan at the rear of the production system or the positive pressure of the titanium tetrachloride mixed gas discharged by the chlorination process to transport the titanium tetrachloride mixed gas to the alkali washing unit.

[0010] Optionally, in the alkali washing unit, the titanium tetrachloride mixed gas is sprayed with an alkali washing liquid, and the mass ratio of the spraying amount of the alkali washing liquid to the theoretical reaction amount of aluminum trichloride in the titanium tetrachloride mixed gas is (0.5-1.5):1.

[0011] Optionally, the alkaline washing solution is a NaOH solution with a concentration of 15% to 25%.

[0012] Optionally, the spraying time is less than 50s.

[0013] The present invention also discloses a titanium tetrachloride pretreatment method, using the titanium tetrachloride pretreatment system; the method comprises the following steps:

[0014] The titanium tetrachloride mixed gas obtained by the chlorination process is subjected to alkali washing to convert aluminum trichloride in the titanium tetrachloride into aluminum trioxide;

[0015] Cooling the titanium tetrachloride mixed gas after alkali washing to obtain titanium tetrachloride liquid;

[0016] The titanium tetrachloride liquid is precipitated to obtain an upper clear liquid and a lower slurry, wherein the upper clear liquid is a crude titanium tetrachloride product and the lower slurry is processed separately.

[0017] Implementing the embodiments of the present invention will have the following beneficial effects:

[0018] The present invention aims at the problem of removing impurities such as aluminum chloride in titanium tetrachloride production, and proposes an innovative pretreatment system and pretreatment method. By using NaOH solution to spray the high-temperature titanium tetrachloride mixed gas output by the chlorination furnace, the sodium hydroxide solution has good impurity removal performance, and it reacts with aluminum chloride to generate aluminum trioxide (Al2O3), which has a large specific gravity and is easy to precipitate and separate. Through this chemical reaction, aluminum impurities in titanium tetrachloride can be efficiently removed, thereby significantly reducing the impurity content in crude titanium tetrachloride. In addition, this method not only improves the quality of crude titanium tetrachloride, but also reduces the impurity removal load in the subsequent refining and purification process, and improves the efficiency of the entire production process.

[0019] Meanwhile, the present invention does not generate brine during the pretreatment process, but only preliminarily removes most of the impurities such as aluminum chloride through reaction, and the reaction generates solid impurities such as aluminum oxide and sodium chloride and a small amount of hydrogen chloride gas.

[0020] In summary, compared with the traditional method, the treatment method of the present invention is more efficient and economical, and is particularly suitable for the treatment of high-temperature titanium tetrachloride mixed gas. By optimizing the spraying process and controlling the concentration of the alkali solution, the impurity removal effect can be further improved at a lower alkali solution concentration, temperature range and shorter contact time, providing a reliable technical solution for the high-purification production of titanium tetrachloride. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited in any way.

[0022] The invention discloses a titanium tetrachloride pretreatment system, comprising a feeding unit, an alkali washing unit, a cooling unit and a sedimentation separation unit which are connected in sequence; the feeding unit is used for conveying titanium tetrachloride mixed gas obtained by a chlorination method to the alkali washing unit; the alkali washing unit is used for alkali washing the titanium tetrachloride mixed gas to convert aluminum trichloride in the titanium tetrachloride into aluminum trioxide; the cooling unit is used for cooling the titanium tetrachloride mixed gas after alkali washing and obtaining titanium tetrachloride liquid; the sedimentation separation unit is used for sedimenting the titanium tetrachloride liquid to obtain an upper clear liquid and a lower slurry, wherein the upper clear liquid is a crude titanium tetrachloride product and the lower slurry is treated separately.

[0023] In a specific embodiment, the chlorination method includes using a molten salt chlorination furnace or a boiling chlorination furnace.

[0024] In a specific embodiment, the titanium tetrachloride mixed gas includes gaseous titanium tetrachloride, aluminum trichloride, ferrous chloride, ferric chloride, titanium slag and coke fine powder.

[0025] In a specific embodiment, the temperature of the titanium tetrachloride mixed gas is 350°C to 550°C.

[0026] In a specific embodiment, the feeding unit comprises utilizing the negative pressure formed by the exhaust fan at the rear of the production system or the positive pressure of the titanium tetrachloride mixed gas discharged from the chlorination process to transport the titanium tetrachloride mixed gas to the alkali washing unit.

[0027] In a specific embodiment, in the alkali washing unit, the titanium tetrachloride mixed gas is sprayed with an alkali washing liquid, and the mass ratio of the spraying amount of the alkali washing liquid to the theoretical reaction amount of aluminum trichloride in the titanium tetrachloride mixed gas is (0.5-1.5):1.

[0028] In a specific embodiment, the alkaline cleaning solution is a NaOH solution with a concentration of 15% to 25%.

[0029] In a specific embodiment, the spraying time is less than 50 s.

[0030] The present invention also discloses a titanium tetrachloride pretreatment method, using the titanium tetrachloride pretreatment system of any embodiment of the present invention;

[0031] The method comprises the following steps:

[0032] The titanium tetrachloride mixed gas obtained by the chlorination process is subjected to alkali washing to convert aluminum trichloride in the titanium tetrachloride into aluminum trioxide;

[0033] Cooling the titanium tetrachloride mixed gas after alkali washing to obtain titanium tetrachloride liquid;

[0034] The titanium tetrachloride liquid is precipitated to obtain an upper clear liquid and a lower slurry, wherein the upper clear liquid is a crude titanium tetrachloride product and the lower slurry is processed separately.

[0035] The following are specific embodiments

[0036] Example 1

[0037] The titanium tetrachloride pretreatment method of this embodiment adopts a titanium tetrachloride pretreatment system, and the system includes a feeding unit, an alkali washing unit, a cooling unit and a sedimentation separation unit connected in sequence.

[0038] The titanium tetrachloride mixed gas at 550°C obtained by the chlorination method is transported to the alkali washing unit for alkali washing through the negative pressure formed by the exhaust fan at the rear of the titanium tetrachloride production system. The alkali washing liquid is a 15% NaOH solution for spraying the titanium tetrachloride mixed gas. The spraying contact time of the NaOH solution and the titanium tetrachloride mixed gas is controlled to be 30s. The spraying amount of the NaOH solution is 1.5 times the theoretical reaction amount of the NaOH solution with the AlCl3 contained in the titanium tetrachloride mixed gas, so as to convert the aluminum trichloride in the titanium tetrachloride into aluminum trioxide. Among them, the chlorination method produces titanium tetrachloride using high-titanium slag as raw material and adopts a molten salt chlorination process. The titanium tetrachloride mixed gas discharged from the chlorination furnace is mainly composed of titanium tetrachloride and impurities such as carbon dioxide, ferric chloride, and AlCl3.

[0039] The titanium tetrachloride mixed gas after alkali washing is transported to a cooling unit for cooling to obtain titanium tetrachloride liquid;

[0040] The titanium tetrachloride liquid is transported to the sedimentation separation unit and sedimented in a sedimentation tank to obtain an upper clear liquid and a lower slurry. The upper clear liquid obtained by sedimentation is the product crude titanium tetrachloride, and the lower slurry containing more impurities obtained by sedimentation is discharged from the system for separate treatment, thereby separating most of the impurities in the titanium tetrachloride.

[0041] Example 2

[0042] The titanium tetrachloride pretreatment method of this embodiment adopts a titanium tetrachloride pretreatment system, and the system includes a feeding unit, an alkali washing unit, a cooling unit and a sedimentation separation unit connected in sequence.

[0043] The titanium tetrachloride mixed gas at 500°C obtained by the chlorination method is transported to the alkali washing unit at the rear of the system through the positive pressure of the titanium tetrachloride mixed gas itself for alkali washing. The alkali washing liquid uses a 25% NaOH solution to spray the titanium tetrachloride mixed gas. The spraying contact time of the NaOH solution and the titanium tetrachloride mixed gas is controlled to be 35s. The spraying amount of the NaOH solution is 0.5 times the theoretical reaction amount of the NaOH solution with the AlCl3 contained in the titanium tetrachloride mixed gas, so as to convert the aluminum trichloride in the titanium tetrachloride into aluminum trioxide. Among them, the chlorination method produces titanium tetrachloride using rutile titanium-rich material as raw material and adopts a boiling chlorination process. The titanium tetrachloride mixed gas discharged from the chlorination furnace is mainly composed of titanium tetrachloride and impurities such as carbon dioxide, ferric chloride, and AlCl3.

[0044] The titanium tetrachloride mixed gas after alkali washing is transported to a cooling unit for cooling to obtain titanium tetrachloride liquid;

[0045] The titanium tetrachloride liquid is transported to the sedimentation separation unit and sedimented in a sedimentation tank to obtain an upper clear liquid and a lower slurry. The upper clear liquid obtained by sedimentation is the product crude titanium tetrachloride, and the lower slurry containing more impurities obtained by sedimentation is discharged from the system for separate treatment, thereby separating most of the impurities in the titanium tetrachloride.

[0046] Example 3

[0047] The titanium tetrachloride pretreatment method of this embodiment adopts a titanium tetrachloride pretreatment system, and the system includes a feeding unit, an alkali washing unit, a cooling unit and a sedimentation separation unit connected in sequence.

[0048] The titanium tetrachloride mixed gas at 450°C obtained by the chlorination method is transported to the alkali washing unit at the rear of the system through the positive pressure of the titanium tetrachloride mixed gas itself for alkali washing. The alkali washing liquid uses a NaOH solution with a concentration of 18% to spray the titanium tetrachloride mixed gas. The spraying contact time of the NaOH solution and the titanium tetrachloride mixed gas is controlled to be 45s. The spraying amount of the NaOH solution is 1.2 times the theoretical reaction amount of the NaOH solution with the AlCl3 contained in the titanium tetrachloride mixed gas, so as to convert the aluminum trichloride in the titanium tetrachloride into aluminum trioxide. Among them, the chlorination method produces titanium tetrachloride using rutile titanium-rich material as raw material and adopts a boiling chlorination process. The titanium tetrachloride mixed gas discharged from the chlorination furnace is mainly composed of titanium tetrachloride and impurities such as carbon dioxide, ferric chloride, and AlCl3.

[0049] The titanium tetrachloride mixed gas after alkali washing is transported to a cooling unit for cooling to obtain titanium tetrachloride liquid;

[0050] The titanium tetrachloride liquid is transported to the sedimentation separation unit and sedimented in a sedimentation tank to obtain an upper clear liquid and a lower slurry. The upper clear liquid obtained by sedimentation is the product crude titanium tetrachloride, and the lower slurry containing more impurities obtained by sedimentation is discharged from the system for separate treatment, thereby separating most of the impurities in the titanium tetrachloride.

[0051] The titanium tetrachloride pretreatment system and method of the present invention can effectively reduce the impurity content in crude titanium tetrachloride produced by the chlorination process and has high treatment efficiency.

[0052] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A titanium tetrachloride pretreatment system, characterized in that: It includes a feeding unit, an alkali washing unit, a cooling unit and a sedimentation separation unit which are connected in sequence; The feeding unit is used to transport the titanium tetrachloride mixed gas obtained by the chlorination process to the alkali washing unit; The alkali washing unit is used to perform alkali washing on the titanium tetrachloride mixed gas to convert aluminum trichloride in the titanium tetrachloride into aluminum trioxide; The cooling unit is used to cool the titanium tetrachloride mixed gas after alkali washing to obtain titanium tetrachloride liquid; The sedimentation separation unit is used to sediment the titanium tetrachloride liquid to obtain an upper clear liquid and a lower slurry, wherein the upper clear liquid is a crude titanium tetrachloride product and the lower slurry is processed separately.

2. The titanium tetrachloride pretreatment system according to claim 1, characterized in that: The chlorination method includes using a molten salt chlorination furnace or a boiling chlorination furnace.

3. The titanium tetrachloride pretreatment system according to claim 1, characterized in that: The titanium tetrachloride mixed gas comprises gaseous titanium tetrachloride, aluminum trichloride, ferrous chloride, ferric chloride, titanium slag and coke fine powder.

4. The titanium tetrachloride pretreatment system according to claim 1, characterized in that: The temperature of the titanium tetrachloride mixed gas is 350°C to 550°C.

5. The titanium tetrachloride pretreatment system according to claim 1, characterized in that: The feeding unit comprises a negative pressure formed by an exhaust fan at the rear of the production system or a positive pressure of the titanium tetrachloride mixed gas discharged by the chlorination process to transport the titanium tetrachloride mixed gas to the alkali washing unit.

6. The titanium tetrachloride pretreatment system according to claim 1, characterized in that: In the alkali washing unit, the titanium tetrachloride mixed gas is sprayed with an alkali washing liquid, and the mass ratio of the spraying amount of the alkali washing liquid to the theoretical reaction amount of aluminum trichloride in the titanium tetrachloride mixed gas is (0.5-1.5):

1.

7. The titanium tetrachloride pretreatment system according to claim 6, characterized in that: The alkaline washing liquid is a NaOH solution with a concentration of 15% to 25%.

8. The titanium tetrachloride pretreatment system according to claim 7, characterized in that: The spraying time is less than 50s.

9. A titanium tetrachloride pretreatment method, characterized in that: Using the titanium tetrachloride pretreatment system as described in any one of claims 1 to 8; The method comprises the following steps: The titanium tetrachloride mixed gas obtained by the chlorination process is subjected to alkali washing to convert aluminum trichloride in the titanium tetrachloride into aluminum trioxide; Cooling the titanium tetrachloride mixed gas after alkali washing to obtain titanium tetrachloride liquid; The titanium tetrachloride liquid is precipitated to obtain an upper clear liquid and a lower slurry, wherein the upper clear liquid is a crude titanium tetrachloride product and the lower slurry is processed separately.