Method for removing aluminum trichloride from crude titanium tetrachloride

Abstract

The invention provides a method for removing aluminum trichloride from crude titanium tetrachloride. The method comprises the following steps: (1) carrying out gradient cooling on the crude titanium tetrachloride containing aluminum chloride; and (2) filtering the crude titanium tetrachloride obtained in the step (1) through a filter provided with a sand core filter plate, and separating the crystallized aluminum trichloride from the crude titanium tetrachloride. The method has the beneficial effects that the problems of high cost, complex operation, long period and reduction of titanium yield of the existing method for removing aluminum from crude titanium tetrachloride are well solved, the mass fraction of aluminum chloride in crude titanium tetrachloride can be reduced to 10 <-5 > or below, the whole process is environment-friendly and pollution-free, the operation is simple, the cost is saved, the titanium loss is less, and the method is suitable for industrial production. The impurity removal method is easy to industrialize.

Description

Technical Field

[0001] The present invention relates to the field of chemical engineering technology and solid waste resource utilization, and specifically relates to a method for removing crude TiCl 4 Medium AlCl 3 method. Technical Background

[0002] TiCl 4 It is used to prepare titanium sponge, titanium dioxide, nano-TiO 2 , titanate and its derivatives and other high value-added titanium products. Currently, TiCl is produced by chlorination method using titanium slag and titanium-rich materials. 4 The industrial production methods include molten salt chlorination and boiling chlorination.

[0003] TiCl prepared by boiling chlorination method 4 There is a certain amount of AlCl 3 Impurities, AlCl 3 It has the same strong corrosive properties as Lewis acid. 4 The saturated solubility in TiCl is highly sensitive to temperature. 4 Medium AlCl 3 If the content exceeds 0.1%, TiCl 4 The problems of accelerated corrosion of production equipment, blockage of heat exchanger pipes, greatly reduced heat exchange effect, and difficulty in removing the refined distillation process seriously affect the normal production. Therefore, in the treatment of crude TiCl 4 Before refining, the crude TiCl 4 Medium AlCl 3 The content is controlled within 0.0025%.

[0004] For crude TiCl 4 Medium AlCl 3 Patent 201310566219.3 mentioned a method of adding sodium chloride to the chlorination process to remove aluminum. 3 Generates high boiling point NaAlCl 4 AlCl 3 However, this method requires the chlorination temperature to reach 800-1000℃, which is relatively high and has poor safety. 4 Medium AlCl 3 The content is still between 0.03% and 0.04%, and the removal effect is poor; in addition, a TiCl 4 However, no specific method for removing impurities from TiCl 4 Removal of AlCl 3The method does not provide relevant data after impurity removal. 4 Medium AlCl 3 There are defects in the impurity removal; Patent 201410420827.8 discloses a method of using alkali solution to achieve TiCl 4 The method of removing impurities, which mentions the use of AlCl 3 Hydrolysis of AlCl 3 impurities, and in this process with crude TiCl 4 Other solid impurities in the crude TiCl 4 AlCl 3 This is also the most commonly used method in industrial production. However, this method requires the addition of alkali solution, the amount of alkali added is difficult to control, it is easy to cause titanium loss, and the alkali addition process is easy to introduce new impurities. Summary of the invention

[0005] The present invention mainly solves the problem that the existing crude TiCl 4 Removal of AlCl 3 The methods for removing impurities generally have the problems of high cost, complicated operation, long cycle and reduced titanium yield. The present invention removes crude TiCl by gradient crystallization. 4 Medium AlCl 3 Impurities, can achieve trace AlCl 3 The removal method is simple, environmentally friendly and easy to industrialize.

[0006] The technical solution of the present invention is as follows:

[0007] 1. A certain flow of inert gas is introduced into the experimental device through the inert gas inlet 6 and the inert gas outlet 11 to keep the device in an inert gas atmosphere;

[0008] 2. Start the magnetic stirring 3 at a certain speed, temporarily turn off the inert gas, and add the crude TiCl containing aluminum chloride into the sandwich reactor 2 through the feed port 8. 4 , then close the feed port 8 and observe the internal temperature displayed by the thermometer 7;

[0009] 3. Add crude TiCl 4 Then, the inert gas is continuously introduced for replacement to keep the device in an inert gas atmosphere. Then, ethylene glycol refrigerant is introduced into the jacket of the jacket reactor through the refrigerant inlet 4 and the refrigerant outlet 5, and the refrigerant is controlled to cool down according to a certain temperature gradient to make AlCl 3 Gradient crystallization;

[0010] 4. After the crystal growth is completed, turn on the peristaltic pump 9 to transfer the crude TiCl 4It is extracted from the sandwich reactor 2 and enters the collection flask 12 after passing through the filter 10 with a sand core filter plate;

[0011] 5. After filtration, remove the sand core filter plate and detect the titanium content in the solution after acid leaching.

[0012] 6. The inert gas in step 1 can be nitrogen or argon, with a nitrogen purity of ≥99% and an argon purity of ≥99%, ensuring that the water vapor after system replacement is ≤1.5ppm and there is no oxygen in the system;

[0013] 7. The inert gas in step 3 can be nitrogen or argon, with a nitrogen purity of ≥99% and an argon purity of ≥99%, ensuring that the water vapor after system replacement is ≤1.5ppm and there is no oxygen in the system;

[0014] 8. Step 3 uses gradient crystallization to make crude TiCl 4 AlCl 3 Crystallization, specifically:

[0015] i. Nucleation stage: the crude TiCl 4 After the addition, the temperature of the ethylene glycol refrigeration liquid in step (1) is rapidly cooled to 5°C at a rate of 3-4°C / min. 4 Part of AlCl 3 Crystals precipitate to form crystal nuclei.

[0016] ii. Crystal growth stage: After nucleation is completed, the temperature of the ethylene glycol freezing liquid is controlled to drop to -25°C at a rate of 0.3-0.5°C / min and then maintained for 50-60 minutes.

[0017] 9. In step 3, the magnetic stirring speed during the nucleation stage is 120-150 rpm to ensure uniform internal temperature and cool down at a certain rate. The magnetic stirring speed during the crystal growth stage is 50-70 rpm, and a low speed is conducive to crystal growth.

[0018] 10. The pore size of the sand core filter plate in step 4 is 3-5 μm, and the filtration connecting pipeline is a sandwich tube. -25℃ refrigerant must be passed into the sandwich for cold preservation. During the crystallization filtration process, each liter of crude TiCl 4 The titanium loss is less than 2g, and the crude TiCl 4 Medium AlCl 3 Content ≤0.001%

[0019] 11. The acid in step 5 is 1:1 hydrochloric acid.

[0020] The beneficial effects brought by the present invention are: the present invention provides a crude TiCl 4 Removal of AlCl 3 The method uses a gradient crystallization method to control the crude TiCl 4AlCl 3 At low temperature, it undergoes two stages of crystallization and crystal growth, and after microporous filtration, AlCl 3 From crude TiCl 4 The method is environmentally friendly, pollution-free, simple to operate, cost-saving, and easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The attached figure shows a crude TiCl 4 Removal of AlCl 3 Schematic diagram of the method DETAILED DESCRIPTION

[0022] In order to better explain the present invention and facilitate understanding, the present invention is described in detail through specific implementation modes.

[0023] Embodiment 1

[0024] Nitrogen with a purity of ≥99% was introduced into the experimental device through the inert gas inlet and inert gas outlet to keep the device in an inert gas atmosphere; 2L crude TiCl 4 Then, the feed port was closed, stirring was started at a speed of 130 rpm, and nitrogen was continued to be introduced for replacement. After the replacement was completed, ethylene glycol refrigerant was introduced into the jacket of the jacket reactor through the refrigerant inlet and the refrigerant outlet. The refrigerant was cooled at 3 °C / min. After cooling to 5 °C, the stirring speed was reduced to 60 rpm, and the refrigerant temperature was controlled to be cooled at 0.5 °C / min. 4 After the temperature reaches -25°C and is maintained at this temperature for 60 min, the peristaltic pump is turned on to transfer the crude TiCl 4 It is extracted from the sandwich reactor and enters the collection flask after passing through a filter with a sand core filter plate with a pore size of 3 to 5 μm. The temperature of the freezing liquid in the filter connecting tube sandwich tube is -25°C. After the filtration is completed, the sand core filter plate is removed, and the titanium content in the solution is detected after acid leaching with 50 ml of hydrochloric acid with a ratio of 1:1 to calculate the titanium loss.

[0025] Embodiment 2

[0026] Nitrogen with a purity of ≥99% was introduced into the experimental device through the inert gas inlet and inert gas outlet to keep the device in an inert gas atmosphere; 2L crude TiCl 4 Then, the feed port was closed, stirring was started at a speed of 130 rpm, and nitrogen was continued to be introduced for replacement. After the replacement was completed, ethylene glycol refrigerant was introduced into the jacket of the jacket reactor through the refrigerant inlet and the refrigerant outlet. The refrigerant was cooled at 3 °C / min. After cooling to 5 °C, the stirring speed was reduced to 60 rpm, and the refrigerant temperature was controlled to be cooled at 0.5 °C / min.4 After the temperature reaches -15°C and is maintained at this temperature for 60 min, the peristaltic pump is turned on to transfer the crude TiCl 4 It is extracted from the sandwich reactor and enters the collection flask after passing through a sand core filter plate filter with a pore size of 3 to 5 μm. The temperature of the freezing liquid in the sandwich tube of the filtration connecting tube is -15°C. After the filtration is completed, the sand core filter plate is removed, and the titanium content in the solution is detected after acid leaching with 50 ml of hydrochloric acid with a ratio of 1:1 to calculate the titanium loss.

[0027] Embodiment 3

[0028] Nitrogen with a purity of ≥99% was introduced into the experimental device through the inert gas inlet and inert gas outlet to keep the device in an inert gas atmosphere; 2L crude TiCl 4 Then, the feed port was closed, stirring was started at a speed of 130 rpm, and nitrogen was continued to be introduced for replacement. After the replacement was completed, ethylene glycol refrigerant was introduced into the jacket of the jacket reactor through the refrigerant inlet and the refrigerant outlet. The refrigerant was cooled at 3 °C / min. After cooling to 5 °C, the stirring speed was reduced to 60 rpm, and the refrigerant temperature was controlled to be cooled at 0.5 °C / min. 4 After the temperature reaches -5°C and is maintained at this temperature for 60 min, the peristaltic pump is turned on to transfer the crude TiCl 4 It is extracted from the sandwich reactor and enters the collection flask after passing through a sand core filter plate filter with a pore size of 3 to 5 μm. The temperature of the freezing liquid in the sandwich tube of the filtration connecting tube is -5°C. After the filtration is completed, the sand core filter plate is removed, and the titanium content in the solution is detected after acid leaching with 50 ml of hydrochloric acid with a ratio of 1:1 to calculate the titanium loss.

[0029] Embodiment 4

[0030] Nitrogen with a purity of ≥99% was introduced into the experimental device through the inert gas inlet and inert gas outlet to keep the device in an inert gas atmosphere; 2L crude TiCl 4 Then, the feed port was closed, stirring was started, the speed was 130 rpm, and nitrogen was continued to be introduced for replacement. After the replacement was completed, ethylene glycol refrigerant was introduced into the jacket of the jacket reactor through the refrigerant inlet and the refrigerant outlet. The refrigerant was cooled at 3 °C / min. After directly cooling to -25 °C, it was maintained at this temperature for 60 min, and the peristaltic pump was turned on to transfer the crude TiCl 4 It is extracted from the sandwich reactor and enters the collection flask after passing through a filter with a sand core filter plate with a pore size of 3 to 5 μm. The temperature of the freezing liquid in the filter connecting tube sandwich tube is -25°C. After the filtration is completed, the sand core filter plate is removed, and the titanium content in the solution is detected after acid leaching with 50 ml of hydrochloric acid with a ratio of 1:1 to calculate the titanium loss.

[0031] Embodiment 5

[0032] Nitrogen with a purity of ≥99% was introduced into the experimental device through the inert gas inlet and inert gas outlet to keep the device in an inert gas atmosphere; 2L crude TiCl 4 Then, the feed port was closed, stirring was started, the speed was 130 rpm, and nitrogen was continued to be introduced for replacement. After the replacement was completed, ethylene glycol refrigerant was introduced into the jacket of the jacket reactor through the refrigerant inlet and the refrigerant outlet. The refrigerant was cooled at 3 °C / min. After directly cooling to -25 °C, it was maintained at this temperature for 60 min, and the peristaltic pump was turned on to transfer the crude TiCl 4 It is extracted from the sandwich reactor and enters the collection flask after passing through a filter with a sand core filter plate with a pore size of 1 to 3 μm. The temperature of the freezing liquid in the filter connecting tube sandwich tube is -25°C. After the filtration is completed, the sand core filter plate is removed, and the titanium content in the solution is detected after acid leaching with 50 ml of hydrochloric acid with a ratio of 1:1 to calculate the titanium loss.

[0033] Embodiment 6

[0034] Nitrogen with a purity of ≥99% was introduced into the experimental device through the inert gas inlet and inert gas outlet to keep the device in an inert gas atmosphere; 2L crude TiCl 4 Then, the feed port was closed, stirring was started at a speed of 130 rpm, and nitrogen was continued to be introduced for replacement. After the replacement was completed, ethylene glycol refrigerant was introduced into the jacket of the jacket reactor through the refrigerant inlet and the refrigerant outlet. The refrigerant was cooled at 3 °C / min. After cooling to 5 °C, the stirring speed was reduced to 60 rpm, and the refrigerant temperature was controlled to be cooled at 0.5 °C / min. 4 After the temperature reaches -25°C and is maintained at this temperature for 60 min, the peristaltic pump is turned on to transfer the crude TiCl 4 It is extracted from the sandwich reactor and enters the collection flask after passing through a sand core filter plate filter with a pore size of 6-10 μm. The temperature of the freezing liquid in the sandwich tube of the filtration connecting tube is -25°C. After the filtration is completed, the sand core filter plate is removed, and the titanium content in the solution is detected after acid leaching with 50 ml of hydrochloric acid with a ratio of 1:1 to calculate the titanium loss.

[0035] Embodiment 7

[0036] Nitrogen with a purity of ≥99% was introduced into the experimental device through the inert gas inlet and inert gas outlet to keep the device in an inert gas atmosphere; 2L crude TiCl 4Then, the feed port was closed, stirring was started at a speed of 130 rpm, and nitrogen was continued to be introduced for replacement. After the replacement was completed, ethylene glycol refrigerant was introduced into the jacket of the jacket reactor through the refrigerant inlet and the refrigerant outlet. The refrigerant was cooled at 3 °C / min. After cooling to 5 °C, the stirring speed was reduced to 60 rpm, and the refrigerant temperature was controlled to be cooled at 0.5 °C / min. 4 After the temperature reaches -25°C and is maintained at this temperature for 60 min, the peristaltic pump is turned on to transfer the crude TiCl 4 It is extracted from the sandwich reactor and enters the collection flask after passing through a sand core filter plate filter with a pore size of 11-15 μm. The temperature of the freezing liquid in the sandwich tube of the filter connecting tube is -25°C. After the filtration is completed, the sand core filter plate is removed, and the titanium content in the solution is detected after acid leaching with 50 ml of hydrochloric acid with a ratio of 1:1 to calculate the titanium loss.

[0037] The specific parameters and experimental data of the above embodiment are as follows:

[0038] Examples 1 to 3: The effects of different filtration temperatures are shown in Table 1 below:

[0039]

[0040] Examples 1, 4, and 5: The effect of gradient crystallization on impurity removal is shown in Table 2 below

[0041]

[0042] Examples 1, 6, and 7: The effects of different filtration apertures are shown in Table 3 below

[0043]

[0044] From the comparative data of the embodiment in Table 1, it can be seen that when the final temperature of the crystal growth stage is -25°C, the AlCl 3 The removal effect is the best; it can be seen from the data in Table 2 that gradient crystallization is significantly better than direct cooling crystallization. Due to direct cooling crystallization, the crude TiCl 4 Using a smaller sand core filter plate can also achieve a better removal rate, but the titanium loss is too high. According to the comparative data in Table 3, the sand core filter plate has a pore size of 3-5 μm for AlCl 3 In summary, the impurity removal effect is best under these conditions of Example 1.

[0045] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for removing aluminum chloride from crude titanium tetrachloride, utilizing the property that the solubility of aluminum chloride in titanium tetrachloride decreases at low temperature, adopting a gradient crystallization method to crystallize aluminum chloride in crude titanium tetrachloride, and then separating it by filtering, comprising the following steps: (1) A certain flow of inert gas is introduced into the experimental device through the inert gas inlet 6 and the inert gas outlet 11 to keep the device in an inert gas atmosphere; (2) turning on the magnetic stirring 3 at a certain speed, temporarily turning off the inert gas, adding crude titanium tetrachloride containing aluminum trichloride into the sandwich reactor 2 through the feed port 8, then closing the feed port 8, and observing the internal temperature displayed by the thermometer 7; (3) After adding the crude titanium tetrachloride, continue to introduce inert gas for replacement to keep the device in an inert gas atmosphere. Then, introduce ethylene glycol refrigerant into the jacket of the jacketed reactor through the refrigerant inlet 4 and the refrigerant outlet 5, and control the refrigerant to cool according to a certain temperature gradient to achieve gradient crystallization of aluminum trichloride; (4) After the crystal growth is completed, the peristaltic pump 9 is turned on to extract the crude titanium tetrachloride in step 3 from the sandwich reactor 2, and the crude titanium tetrachloride enters the collection flask 12 after passing through the filter 10 with a sand core filter plate; (5) After filtration, remove the sand core filter plate and detect the titanium content in the solution after acid leaching.

2. A method for removing aluminum chloride from crude titanium tetrachloride as described in claim 1, characterized in that: The inert gas in step (1) can be nitrogen or argon, with the purity of nitrogen being ≥99% and the purity of argon being ≥99%, ensuring that the water vapor after system replacement is ≤1.5ppm and there is no oxygen in the system.

3. A method for removing aluminum chloride from crude titanium tetrachloride as described in claim 1, characterized in that: The inert gas in step (3) can be nitrogen or argon, with nitrogen purity ≥99% and argon purity ≥99%, ensuring that the water vapor after system replacement is ≤1.5ppm and there is no oxygen in the system.

4. A method for removing aluminum chloride from crude titanium tetrachloride as described in claim 1, characterized in that: Step (3) uses a gradient crystallization method to crystallize aluminum chloride in crude titanium tetrachloride, specifically: i. Nucleation stage: After the crude titanium tetrachloride is added, the temperature of the ethylene glycol refrigeration liquid in step (1) is rapidly cooled to 5°C at a rate of 3 to 4°C / min, and part of the aluminum chloride in the crude titanium tetrachloride crystallizes and precipitates to form crystal nuclei; ii. Crystal growth stage: After nucleation is completed, the temperature of the ethylene glycol freezing liquid is controlled to drop to -25°C at a rate of 0.3-0.5°C / min and then maintained for 50-60 minutes.

5. A method for removing aluminum chloride from crude titanium tetrachloride as claimed in claim 1, characterized in that: In step (3), the magnetic stirring speed during the nucleation stage is 120-150 rpm to ensure uniform internal temperature and to cool down at a certain rate. The magnetic stirring speed during the crystal growth stage is 50-70 rpm, and a low speed is conducive to crystal growth.

6. A method for removing aluminum chloride from crude titanium tetrachloride as claimed in claim 1, characterized in that: In step (4), the pore size of the sand core filter plate is 3-5 μm, and the filtration connecting pipeline is a sandwich tube, and a -25°C refrigerant needs to be passed into the sandwich for cold preservation. The titanium loss per liter of crude titanium tetrachloride during the crystallization filtration process is less than 2 g, and the aluminum trichloride content in the crude titanium tetrachloride after crystallization filtration is ≤0.001%.

7. A method for removing aluminum chloride from crude titanium tetrachloride as claimed in claim 1, characterized in that: The acid in step (5) is 1:1 hydrochloric acid.

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