Method and device for producing TC4 powder

Abstract

The invention discloses a method and device for producing TC4 powder, and the method comprises the following steps: 1) taking potassium fluotitanate as a raw material, taking aluminum powder and / or vanadium-containing aluminum powder as a reducing agent, uniformly mixing the raw material and the reducing agent, and pressing into pellets; (2) the pellets are heated to 200-300 DEG C in a reduction furnace in an inert atmosphere, and heat preservation is conducted; then heating to 650-850 DEG C in an inert atmosphere, keeping the temperature, and carrying out an aluminothermic reduction reaction to obtain an aluminothermic reduction reaction product; and 3) carrying out vacuum distillation separation on the aluminothermic reduction reaction product to separate out a TC4 product and a distillation product. According to the method, the potassium fluotitanate is used as the raw material, the aluminum powder and / or the vanadium-containing aluminum powder are / is used as the reducing agent, the TC4 alloy is directly synthesized through the two-stage aluminothermic reduction method, the technological process is simple, energy consumption can be effectively reduced, and the production cost is reduced. The device is used for directly synthesizing the TC4 alloy by a two-stage aluminothermic reduction method, and has the characteristics of simple structure, good synthesis effect and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical metallurgy production, and in particular relates to a method and a device for producing TC4 powder. Background Art

[0002] Titanium and titanium alloys have excellent properties such as low density, high specific strength, corrosion resistance, weldability, and non-magnetism. They have irreplaceable application value in cutting-edge fields such as aerospace, ships, weapons, marine engineering, and nuclear industry.

[0003] Titanium is a raw material for the preparation of titanium alloys, and the optimization and improvement of its smelting process will inevitably affect the preparation cost and application areas of titanium alloys. Titanium metallurgists have developed a variety of extraction processes, which are mainly divided into two categories: molten salt electrolysis and thermal reduction. The molten salt electrolysis method is a method for preparing titanium using titanium chloride or oxide as raw material, and an electrolyte composed of alkali metal or alkaline earth metal chloride or fluoride as a molten salt system for direct current electrolysis. One type of molten salt electrolysis method is that the titanium compound dissolves in the molten salt to form titanium ions, which migrate directionally to the cathode to obtain electrons to obtain metallic titanium; the representative method is the TiCl4 molten salt electrolysis method, that is, direct current electrolysis is carried out under an inert atmosphere and a chloride molten salt system, and metallic titanium is obtained at the cathode. This method has problems such as low solubility of titanium chloride, large fluctuations in electrolyte composition, low current efficiency, uncontrollable reverse reaction, and difficulty in sealing the electrolytic cell, and has not been able to achieve industrial application. Another type of molten salt electrolysis method is to use titanium oxide as the cathode, electrolyze in a chloride electrolyte, and obtain metallic titanium at the cathode. The representative method is the FFC method.

[0004] Fray DJ et al. made TiO2 powder into a porous sheet cathode and electrolyzed it in calcium chloride molten salt, combining direct electrolytic reduction and electrochemical deoxidation to obtain metallic titanium at the cathode (see Chen GZ, Fray DJ, Farthing TW. Direct electrochemical reduction of titanium dioxide to titanium in moltencalcium chloride [J]. Nature, 2000, 407: 361-364.). However, its industrial production has faced many technical difficulties so far. On this basis, Ono and Suzuki et al. proposed the OS method and the optimized MSE method of electrolyzing CaO in molten salt to obtain calcium element and then reducing TiO2 with calcium heat to prepare metallic titanium (see Ono K, Suzuki R O. A new concept for producing Ti sponge: calciothermic reduction [J]. JOM, 2002, 54 (2): 59-61.). However, there are still problems such as low yield, high energy consumption and complex equipment. In addition to the above two methods, "Study on the Application of Solid Oxygen Permeable Membrane Method in the Preparation of Metallic Titanium" (Shanghai University, Proceedings of the 2008 National Conference on Metallurgical Physical Chemistry) proposed the SOM method for extracting titanium using solid oxygen permeable membranes; Zhu Hongmin et al. proposed the USTB method for extracting titanium using soluble anode TiCxOy molten electrolysis (see Jiao SQ, Zhu H M. Novel metallurgical process for titaniumproduction[J]. Journal of Materials Research, 2006, 21(9): 2172-2175). The experimental current efficiency at the 10,000-ampere level reached over 85%, and the titanium purity was 99.9%. It is currently undergoing active industrial-level verification.

[0005] Up to now, due to the problems and limitations in the above-mentioned methods for preparing titanium and titanium alloys, industrial pure titanium is still prepared using the Kroll method. Under the premise that low-cost smelting of pure titanium cannot be achieved, the cost of preparing titanium alloys is relatively high. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for producing TC4 powder with a simple process flow; the present invention also provides a device for producing TC4 powder.

[0007] To solve the above technical problems, the technical solution adopted by the method of the present invention includes the following steps: 1) using potassium fluorotitanate as a raw material and aluminum powder and / or vanadium-containing aluminum powder as a reducing agent, mixing the raw material and the reducing agent and pressing them into pellets; 2) The pellets are heated to 200-300° C. in a reduction furnace under an inert atmosphere and kept warm; then heated to 650-850° C. in an inert atmosphere and kept warm to perform an aluminothermic reduction reaction to obtain an aluminothermic reduction reaction product; 3) The aluminothermic reduction reaction product is subjected to vacuum distillation separation to separate the TC4 product and the distillation product.

[0008] Furthermore, in step 2), the temperature is heated to 200-300° C. at a heating rate of 5-10° C. / min.

[0009] Furthermore, in step 2), the temperature is kept at 200-300° C. for 2 hours or more.

[0010] Furthermore, in step 2), the aluminothermic reduction reaction is carried out at 650-850° C. for 3 hours or more.

[0011] Furthermore, in step 3), the aluminothermic reduction reaction product is heated to 950-1200° C. and separated by vacuum distillation.

[0012] Furthermore, in step 1), the oxygen content of the raw material is controlled at 0.05% or less, and the particle size is controlled between 100 mesh and 200 mesh, accounting for 80% or more; the oxygen content of the reducing agent is controlled at 0.1% or less, and the particle size is controlled between 120 mesh and 200 mesh, accounting for 80% or more.

[0013] In order to solve the above technical problems, the technical solution adopted by the device of the present invention is: it includes a reactor, a cooler, a crystallizer and a vacuum pump system; the reactor is provided with a heating structure, and a material tray is provided in the furnace; the upper part of the reactor is connected to the lower part of the cooler through a pipeline, and the crystallizer extends into the cooler from the upper opening of the cooler and seals the upper opening of the cooler; the vacuum pump system is connected to the inner upper part of the crystallizer.

[0014] Furthermore, a vent pipe is provided on the top of the reactor, and the vent pipe is connected to the inert gas pipeline.

[0015] Furthermore, the heating structure of the reaction furnace is a heating coil arranged around the furnace, and the heating coil is connected to a power supply.

[0016] Furthermore, cooling water passages are provided around the cooler, and the cooling water passages are connected to the cooling water pipeline.

[0017] The beneficial effects of adopting the above technical solution are: the method of the present invention uses potassium fluorotitanate as a raw material, aluminum powder or vanadium-containing aluminum powder as a reducing agent, adopts a two-stage aluminothermic reduction method to directly synthesize TC4 alloy, and uses vacuum distillation to separate the TC4 product. The process flow is simple, and can effectively reduce energy consumption and reduce production costs.

[0018] The device of the present invention is used for directly synthesizing TC4 alloy by a two-stage aluminothermic reduction method, and has the characteristics of simple structure, good synthesis effect, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] Figure 1 It is a structural schematic diagram of the device of the present invention.

[0021] In the figure: 1 - reactor, 2 - heating coil, 3 - material tray, 4 - reactor cover, 5 - vent pipe, 6 - cooler, 7 - cooling water passage, 8 - crystallizer, 9 - crystallization baffle, 10 - cooling cover, 11 - vacuum pump system. DETAILED DESCRIPTION

[0022] The method for producing TC4 powder includes the following steps: 1) Pellet preparation: Potassium fluorotitanate is used as the raw material, and aluminum powder and / or vanadium-containing aluminum powder is used as the reducing agent. Preferably, a mixture of aluminum powder and vanadium-containing aluminum powder is used, and the vanadium content of the vanadium-containing aluminum powder is 5-8wt% to ensure uniform dispersion of the vanadium element in the raw material. The proportions of the materials are adjusted according to the product requirements, and the reaction equation for the preparation ratio is: 3K2TiF6+(3x+4)Al=3TiAl x +2K3AlF6+2AlF3, where 3≥x≥0.

[0023] The raw materials and the reducing agent are mixed for 50 minutes or longer; then pressed into pellets with a thickness of 12 to 18 mm and a pressing pressure of 20 to 50 MPa, preferably 30 to 35 MPa; the pellets are dried under vacuum for 24 to 48 hours. The oxygen content of the raw materials is controlled to be 0.05 wt% or less, and the particle size is controlled to be between 100 mesh and 200 mesh, accounting for 80 wt% or more, preferably potassium fluorotitanate; the oxygen content of the reducing agent is controlled to be 0.1 wt% or less, and the particle size is controlled to be between 120 mesh and 200 mesh, accounting for 80 wt% or more, preferably a mixture of vanadium-containing aluminum powder and aluminum powder, and the vanadium content of the vanadium-containing aluminum powder is 5.9% to 6.1 wt%.

[0024] 2) Two-stage aluminothermic reduction: The pellets are placed in a reduction furnace, which is evacuated to a negative pressure of 1 Pa or less. The oxygen in the reduction furnace is then replaced with an inert gas, preferably three or more times. The furnace is heated to 200-300°C, preferably 250°C, at a heating rate of 5°C / min, under an inert gas atmosphere. The furnace is then held at this temperature for 2 hours or more. The furnace is again evacuated to a negative pressure of 1 Pa or less, and the oxygen in the reduction furnace is replaced with an inert gas, preferably three or more times. The furnace is then heated to 650-850°C at a heating rate of 5°C / min under an inert gas atmosphere. The temperature is maintained for 3 hours or more to carry out an aluminothermic reduction reaction and obtain a reaction product. During the heating and holding processes, the inert atmosphere is maintained at a slightly positive pressure of ≤0.02 MPa. The purpose of the evacuation and inert gas replacement is to remove oxygen from the reaction furnace and reduce its impact on the materials. Argon is preferably used as the inert gas.

[0025] 3) Separation: The reaction product is heated to 950-1200°C at a rate of 5-10°C / min under an inert atmosphere, and vacuum distilled for separation for 3 hours or more to separate the TC4 product and the distillation product. An inert gas is then introduced into the reduction furnace to a slightly positive pressure for gas protection, with the positive pressure being ≤0.02 MPa. During the cooling process, the argon pressure in the furnace is maintained at a slightly positive pressure of ≤0.02 MPa. As the temperature decreases, the distillation product crystallizes into a solid. The main components of the distillation product are K3AlF6, AlF3, low-valent titanium fluoride, and some aluminum.

[0026] 4) The TC4 powder obtained by this method has an aluminum content of 5.5 to 6.7 wt%, an iron content of less than 0.3 wt%, a vanadium content of 3.5 to 4.5 wt%, an oxygen content of less than 0.2 wt%, a nitrogen content of less than 0.15 wt%, and a content of other metal impurities of less than 0.05 wt%.

[0027] Figure 1As shown, the apparatus for producing TC4 powder comprises a reactor 1, a cooler 6, a crystallizer 8, and a vacuum pump system 11. The reactor 1 is a cylindrical structure with a reactor cover 4 at the top and a material tray 3 within the furnace. The reactor 1 is equipped with a heating structure comprising heating coils 2 arranged around the furnace, which are connected to a power source. The reactor cover 4 is provided with a vent pipe 5, which is connected to an inert gas pipeline. The upper portion of the reactor 1 is connected to the lower portion of the cooler 6 via a pipeline. The cooler 6 is a cylindrical structure equipped with a cooling structure comprising a cooling water passage 7 surrounding the cooler 6, the water inlet of which is connected to the cooling water pipeline. The lower middle portion of the crystallizer 8 extends into the cooler 6 through the upper opening of the cooler 6, which seals the upper opening. A cooling cover 10 is provided on the top of the crystallizer 8. The vacuum pump system 11 is connected to the upper inner portion of the crystallizer 8.

[0028] Example 1: This method for producing TC4 powder uses the above-mentioned device, and the specific process is as follows.

[0029] 1) Use 10 kg of potassium fluorotitanate as the raw material, 1.3 kg of vanadium-containing aluminum powder with a 5.7% vanadium content, and 0.47 kg of pure aluminum powder as the reducing agent. Mix the raw materials and reducing agent for 50 minutes, press them into pellets, and dry them under vacuum for 24 hours.

[0030] 2) Place the pellets into the material tray 3 of the reactor 1, and then seal the reactor lid 4. Evacuate the entire equipment through the vacuum system 11 to a negative pressure of 1 Pa, then introduce argon through the vent pipe 5 to replace the oxygen in the system. Repeat this argon replacement three times. In an argon atmosphere, heat the temperature at room temperature to 250°C at a rate of 5°C / min and let it stand at 250°C for 2 hours. Then, evacuate the equipment again and introduce argon to replace the gas in the reduction furnace and remove the small amount of oxygen in the reduction furnace. In an argon atmosphere, heat the temperature from 250°C to 750°C at a rate of 5°C / min and maintain it at 750°C for 3 hours to carry out the reduction reaction.

[0031] 3) The reaction product is heated from 750°C to 1150°C / min at a rate of 5°C / min and distilled at 1150°C under vacuum. The distilled K3AlF6, AlF3, and low-valent titanium fluoride are crystallized into a solid on crystallizer 8 and crystallization baffle 9 via cooler 6. Distillation is continued for 3 hours to completely remove the fluoride. After distillation, argon is introduced into the reactor and the temperature is naturally lowered to room temperature. The reactor lid 4 is opened, the material tray 3 is lifted out, and the TC4 powder is removed. The cooler 6 and cooling lid 10 are opened, the crystallizer 8 and crystallization baffle 9 are lifted out, and the chlorides on the cooler, crystallizer, and crystallization baffle are cleaned.

[0032] 4) The components of the TC4 powder product obtained in this example include (wt%): V 3.81%, Al 5.66%, Fe 0.120%, N 0.003%, and O 0.168%.

[0033] Example 2: This method for producing TC4 powder uses the above-mentioned device, and the specific process is as follows.

[0034] 1) Use 10 kg of potassium fluorotitanate as the raw material, 1.23 kg of vanadium-containing aluminum powder with a 6.3% vanadium content, and 0.5 kg of pure aluminum powder as the reducing agent. Mix the raw materials and reducing agent for 60 minutes, press them into pellets, and dry them under vacuum for 24 hours.

[0035] 2) Place the pellets into the material tray 3 of the reactor 1, and then seal the reactor lid 4. Evacuate the entire equipment through the vacuum system 11 to a negative pressure of 1 Pa, then introduce argon through the vent pipe 5 to replace the oxygen in the system. Repeat this argon replacement three times. In an argon atmosphere, heat the temperature at room temperature to 200°C at a rate of 7°C / min and let it stand at 200°C for 2.5 hours. Then, evacuate the equipment again and introduce argon to replace the gas in the reduction furnace and remove the small amount of oxygen in the reduction furnace. In an argon atmosphere, heat the temperature from 200°C to 800°C at a rate of 8°C / min and keep it at 800°C for 3 hours to carry out the reduction reaction.

[0036] 3) The reaction product is heated from 800°C to 1100°C / min at a rate of 10°C / min and distilled at 1100°C under vacuum. The distilled K3AlF6, AlF3, and low-valent titanium fluoride are crystallized into a solid on crystallizer 8 and crystallization baffle 9 via cooler 6. Distillation is continued for 3 hours to completely remove the fluoride. After distillation, argon is introduced into the reactor to cool naturally to room temperature. The reactor lid 4 is opened, the material tray 3 is lifted out, and the TC4 powder is removed. The cooler 6 and cooling lid 10 are opened, the crystallizer 8 and crystallization baffle 9 are lifted out, and the chlorides on the cooler, crystallizer, and crystallization baffle are cleaned.

[0037] 4) The components of the TC4 powder product obtained in this example include (wt%): V 4.09%, Al 6.29%, Fe 0.121%, N 0.004%, and O 0.186%.

[0038] Example 3: This method for producing TC4 powder uses the above-mentioned device, and the specific process is as follows.

[0039] 1) Use 10 kg of potassium fluorotitanate as the raw material, 1.275 kg of vanadium-containing aluminum powder with a 6.2% vanadium content, and 0.495 kg of pure aluminum powder as the reducing agent. Mix the raw materials and reducing agent for 55 minutes, press into pellets, and dry under vacuum for 48 hours.

[0040] 2) Place the pellets into the material tray 3 of the reactor 1, and then seal the reactor lid 4. Evacuate the entire equipment through the vacuum system 11 to a negative pressure of 1 Pa, then introduce argon through the vent pipe 5 to replace the oxygen in the system. Repeat this argon replacement three times. In an argon atmosphere, heat the temperature at room temperature to 300°C at a rate of 8°C / min and let it stand at 300°C for 2 hours. Then, evacuate the equipment again and introduce argon to replace the gas in the reduction furnace and remove the small amount of oxygen in the reduction furnace. In an argon atmosphere, heat the temperature from 300°C to 850°C at a rate of 10°C / min and keep it at 850°C for 4 hours to carry out the reduction reaction.

[0041] 3) The reaction product is heated from 850°C to 1200°C / min at a rate of 7°C / min and distilled at 1200°C under vacuum and negative pressure. The distilled K3AlF6, AlF3, and low-valent titanium fluoride are crystallized into a solid on crystallizer 8 and crystallization baffle 9 through cooler 6. Distillation is continued for 3 hours to completely remove the fluoride. After distillation, argon is introduced into the reactor to naturally cool to room temperature. The reactor lid 4 is opened, the material tray 3 is lifted out, and the TC4 powder is removed. The cooler 6 and cooling lid 10 are opened, the crystallizer 8 and crystallization baffle 9 are lifted out, and the chloride on the cooler, crystallizer, and crystallization baffle is cleaned.

[0042] 4) The components of the TC4 powder product obtained in this example include (wt%): V 4.11%, Al 6.14%, Fe 0.119%, N 0.004%, and O 0.193%.

[0043] Example 4: This method for producing TC4 powder uses the above-mentioned device, and the specific process is as follows.

[0044] 1) Use 10 kg of sodium fluorotitanate as the raw material, 1.275 kg of vanadium-containing aluminum powder with a 6.2% vanadium content, and 0.495 kg of pure aluminum powder as the reducing agent. Mix the raw materials and reducing agent for 40 minutes, press into pellets, and dry under vacuum for 36 hours.

[0045] 2) Place the pellets into the material tray 3 of the reactor 1, and then seal the reactor lid 4. Evacuate the entire equipment through the vacuum system 11 to a negative pressure of 1 Pa, then introduce argon through the vent pipe 5 to replace the oxygen in the system. Repeat this argon replacement three times. In an argon atmosphere, heat the temperature at room temperature to 250°C at a rate of 10°C / min and let it stand at 250°C for 3 hours. Then, evacuate the equipment again and introduce argon to replace the gas in the reduction furnace and remove the small amount of oxygen in the reduction furnace. In an argon atmosphere, heat the temperature from 250°C to 650°C at a rate of 6°C / min and keep it at 650°C for 3.5 hours to carry out the reduction reaction.

[0046] 3) The reaction product is heated from 650°C to 950°C / min at a rate of 6°C / min and distilled at 950°C under vacuum. The distilled K3AlF6, AlF3, and low-valent titanium fluoride are crystallized into a solid on crystallizer 8 and crystallization baffle 9 via cooler 6. Distillation is continued for 3 hours to completely remove the fluoride. After distillation, argon is introduced into the reactor and the temperature is naturally lowered to room temperature. The reactor lid 4 is opened, the material tray 3 is lifted out, and the TC4 powder is removed. The cooler 6 and cooling lid 10 are opened, the crystallizer 8 and crystallization baffle 9 are lifted out, and the chlorides on the cooler, crystallizer, and crystallization baffle are cleaned.

[0047] 4) The components of the TC4 powder product obtained in this example include (wt%): V 3.87%, Al 5.97%, Fe 0.118%, N 0.009%, and O 0.224%.

Claims

1. A method for producing TC4 powder, characterized in that: The method comprises the following steps: 1) using potassium fluorotitanate as a raw material and aluminum powder and / or vanadium-containing aluminum powder as a reducing agent, mixing the raw material and the reducing agent and pressing the mixture into pellets; 2) The pellets are heated to 200-300° C. in a reduction furnace under an inert atmosphere and kept warm; then heated to 650-850° C. in an inert atmosphere and kept warm to perform an aluminothermic reduction reaction to obtain an aluminothermic reduction reaction product; 3) The aluminothermic reduction reaction product is subjected to vacuum distillation separation to separate the TC4 product and the distillation product.

2. The method for producing TC4 powder according to claim 1, wherein: In the step 2), the temperature is heated to 200-300° C. at a heating rate of 5-10° C. / min.

3. The method for producing TC4 powder according to claim 1, wherein: In step 2), the temperature is kept at 200-300° C. for 2 hours or more.

4. The method for producing TC4 powder according to claim 1, wherein: In the step 2), the aluminothermic reduction reaction is carried out at 650-850° C. for 3 hours or more.

5. The method for producing TC4 powder according to claim 1, wherein: In the step 3), the aluminothermic reduction reaction product is heated to 950-1200° C. and separated by vacuum distillation.

6. A method for producing TC4 powder according to any one of claims 1 to 5, characterized in that: In the step 1), the oxygen content of the raw material is controlled at 0.05% or less, and the particle size is controlled between 100 mesh and 200 mesh, accounting for 80% or more; the oxygen content of the reducing agent is controlled at 0.1% or less, and the particle size is controlled between 120 mesh and 200 mesh, accounting for 80% or more.

7. A device for producing TC4 powder, used in the method according to any one of claims 1 to 6, characterized in that: The invention comprises a reaction furnace (1), a cooler (6), a crystallizer (8) and a vacuum pump system (11); the reaction furnace (1) is provided with a heating structure, and a material tray (3) is provided in the furnace; the upper part of the reaction furnace (1) is connected to the lower part of the cooler (6) through a pipeline, and the crystallizer (8) extends into the cooler (6) from the upper opening of the cooler (6) and seals the upper opening of the cooler (6); the vacuum pump system (11) is connected to the inner upper part of the crystallizer (8).

8. The device for producing TC4 powder according to claim 7, characterized in that: A vent pipe (5) is provided on the top of the reactor (1), and the vent pipe (5) is connected to an inert gas pipeline.

9. The device for producing TC4 powder according to claim 7, characterized in that: The heating structure of the reaction furnace (1) is a heating coil (2) arranged around the furnace, and the heating coil (2) is connected to a power supply.

10. The device for producing TC4 powder according to claim 7, 8 or 9, characterized in that: The cooler (6) is provided with cooling water passages (7) around it, and the cooling water passages (7) are connected to the cooling water pipeline.

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