Ferrotitanium vacuum arc furnace machining device and method based on dynamic electrode regulation and control

Abstract

The invention discloses a ferrotitanium vacuum arc furnace machining device and method based on dynamic electrode regulation and control. The ferrotitanium vacuum arc furnace machining device comprises a furnace body (1); a crucible (2); a graphite electrode (3); the cylindrical protective shell (4) is fixedly connected to the top of the furnace body and is positioned outside the graphite electrode; the first gas pipeline (5) is obliquely communicated between the side wall of the furnace body and the upper part of the cylindrical protective shell, and the first gas pipeline is used for introducing high-pressure inert gas; and the second gas pipeline (6) is horizontally communicated between the side wall of the furnace body and the lower part of the cylindrical protective shell, and is used for introducing low-pressure inert gas. The method has the beneficial effects that the high-pressure inert gas and the low-pressure inert gas can form an air curtain covering the surface, especially the tail end, of the graphite electrode at the intersection, sublimated carbon particles are inhibited from being diffused to a molten pool, and meanwhile a trace amount of oxygen is isolated to prevent oxidation.

Description

Technical Field

[0001] The present invention relates to the technical field of vacuum arc furnaces, and particularly to a vacuum arc furnace processing device and method for processing ferro-titanium alloys. Background Art

[0002] Ferro-titanium is an intermediate alloy of titanium and iron, which is used as a deoxidizer, degassing agent and carbon and sulfur stabilizer in steel smelting. Ferro-titanium plays a key role in the production of steel. Through the titanium element it contains, the molten steel can be effectively purified, and the quality and performance of steel can be improved. When smelting ferro-titanium alloys, a vacuum arc furnace is generally used. In a controlled vacuum environment, ilmenite is heated by an electric arc, instantaneously melted and formed into liquid metal, and the molten metal is cooled to a solid state to form sponge titanium. However, the melting point of ferro-titanium alloys is relatively high, about 1500°C - 1600°C, and the use of vacuum arc furnaces often consumes a high amount of energy. When using graphite electrodes, although the inside of the vacuum arc furnace is a vacuum environment, it is difficult to completely avoid the entry of oxygen in actual production. When there is a small amount of oxygen present, the graphite electrode is prone to oxidation reaction at high temperatures, generating gases such as carbon dioxide or carbon monoxide, thereby accelerating the loss of the electrode, reducing the performance and service life of the electrode. Graphite undergoes obvious oxidation (generating CO) above 600°C when the vacuum degree < 10 -2 Pa or contains trace amounts of oxygen, resulting in the loosening of the electrode surface and an increase in resistivity. In a vacuum environment (especially when the vacuum degree < 10 - 3 Pa), the surface atoms of graphite sublimate and deposit on the surface of the molten pool, or form carbon particle inclusions. If there is residual water vapor or oxygen in the furnace, graphite reacts with oxygen to generate CO / CO2, and CO decomposes into C and O at high temperatures, exacerbating the carbon-oxygen double pollution.

[0003] For example, Chinese Patent Publication No. CN114424010A discloses a non-water-cooled consumable electrode type vacuum arc furnace for continuous processes. The consumable electrode type vacuum arc furnace includes a shell, a flange port and electrical connectors of the furnace, and does not require water cooling to cool the electrode or any other part of the furnace. This patent focuses on solving the cooling problem and does not involve the regulation of graphite electrodes.

[0004] For another example, Chinese Utility Model Patent Publication No. CN206056242U discloses an electrode position adjusting device for a vacuum arc furnace, which mainly consists of a frame, a fence, a rectangular support plate and an electric push rod assembly. Among them, the electric push rod assembly includes a push rod, a front pin, a rear pin, a front pillar, a rear pillar, a front pillar seat, a rear pillar seat, a backing plate, bolts and an electrode. The front pin is sleeved on the front pillar, the front pillar is fixed on the front pillar seat, and the front pillar seat is fixed on the frame. The rear pin is sleeved on the rear pillar, the rear pillar is fixed on the rear pillar seat, and the rear pillar seat is fixed on the rectangular support plate through the backing plate. Both ends of the push rod are connected to the front pin and the rear pin through bolts. The motor controls the telescopic movement of the push rod through rotation, and pushes or pulls the rectangular support plate that can fix the electrode of the vacuum arc furnace. This patent is used to solve the problem of creeping arc between the electrode and the crucible, and does not involve the problems of oxidation of graphite electrodes and carbon pollution. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the graphite electrodes of the existing processing device for titanium ferroalloy in a titanium ferro vacuum arc furnace are easily oxidized and cause carbon pollution. Therefore, a processing device and method for a vacuum arc furnace for processing titanium ferroalloy are provided.

[0006] The technical solution of the present invention is: a titanium ferro vacuum arc furnace processing device based on dynamic electrode regulation, including: a furnace body; a crucible; a graphite electrode; and further including: a cylindrical protective shell, the cylindrical protective shell is fixedly connected to the top of the furnace body and is located outside the graphite electrode; a first gas pipeline, the first gas pipeline is inclined and communicated between the side wall of the furnace body and the upper part of the cylindrical protective shell, and the first gas pipeline is used to introduce high-pressure inert gas; a second gas pipeline, the second gas pipeline is horizontally communicated between the side wall of the furnace body and the lower part of the cylindrical protective shell, and the second gas pipeline is used to introduce low-pressure inert gas.

[0007] In the above solution, the pressure of the high-pressure inert gas is 1.5 bar - 2.5 bar, and the pressure of the low-pressure inert gas is 0.5 bar - 1.2 bar.

[0008] An improvement to the above solution is that a conical diversion part is provided at the bottom of the cylindrical protective shell, and a spiral diversion groove is provided on the inner wall of the conical diversion part.

[0009] In the above solution, the high-pressure inert gas is input in a pulsed manner, the input frequency of the high-pressure inert gas is 5 - 10 Hz, the duty cycle is 60% - 70%, and the input of the low-pressure inert gas is continuous.

[0010] A further improvement to the above solution is that a third gas pipeline is communicated between the cylindrical protective shell and the side wall of the furnace body, and the third gas pipeline is used to output inert gas.

[0011] A further improvement of the above solution is that an air extraction pump communicated with the third gas pipeline is installed outside the furnace body.

[0012] A further improvement of the above solution is that a ring-shaped base is rotatably connected to the top of the furnace body between the cylindrical protective shell and the graphite electrode. A baffle extends downward from the bottom of the ring-shaped base into the furnace body. A baffle plate is provided at the bottom of the baffle to cooperate with the first gas pipeline to change the flow direction of the high-pressure inert gas.

[0013] Another improvement of the above solution is that a handle is provided on the ring-shaped base.

[0014] The usage method of the titanium-iron vacuum arc furnace processing device based on dynamic electrode regulation includes the following steps: input high-pressure inert gas into the first gas pipeline through an external gas source, and at the same time input low-pressure inert gas into the second gas pipeline through an external gas source. The high-pressure inert gas and the low-pressure inert gas meet and form an air curtain at least at the end of the graphite electrode to prevent graphite oxidation and pollution.

[0015] The beneficial effect of the present invention is that the high-pressure inert gas and the low-pressure inert gas will form an air curtain covering the surface of the graphite electrode, especially at the end, inhibiting the diffusion of sublimated carbon particles to the molten pool and at the same time isolating trace oxygen to prevent oxidation. Description of the Drawings

[0016] Figure 1 is a schematic diagram of the titanium-iron vacuum arc furnace processing device based on dynamic electrode regulation of the present invention; Figure 2 is Figure 1 a schematic diagram of the cooperation of the cylindrical protective shell, the first gas pipeline and the second gas pipeline in Figure 3 is a schematic diagram of the cooperation of the preferred ring-shaped base, baffle and baffle plate in the present invention; In the figure, 1. Furnace body, 2. Crucible, 3. Graphite electrode, 4. Cylindrical protective shell, 5. First gas pipeline, 6. Second gas pipeline, 7. Conical diversion part, 8. Spiral diversion groove, 9. Third gas pipeline, 10. Air extraction pump, 11. Ring-shaped base, 12. Baffle, 13. Baffle plate. Detailed Embodiments

[0017] Combined with the drawings, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0018] A titanium-iron vacuum arc furnace processing device based on dynamic electrode regulation, comprising: a furnace body 1; a crucible 2; a graphite electrode 3; further comprising: a cylindrical protective shell 4, which is fixedly connected to the top of the furnace body and is located outside the graphite electrode; a first gas pipeline 5, which is obliquely connected between the side wall of the furnace body and the upper part of the cylindrical protective shell, and the first gas pipeline is used for introducing high-pressure inert gas; a second gas pipeline 6, which is horizontally connected between the side wall of the furnace body and the lower part of the cylindrical protective shell, and the second gas pipeline is used for introducing low-pressure inert gas.

[0019] The cylindrical protective shell can be made of high-temperature oxide ceramics such as alumina and zirconia ceramics. The high-pressure inert gas and the low-pressure inert gas can be the same inert gas such as argon, or different inert gases. For example, the high-pressure inert gas is argon and the low-pressure inert gas is nitrogen. Since the cost of nitrogen is lower than that of argon, the use cost of inert gas can be reduced.

[0020] When using a graphite electrode, carbon atoms in the graphite enter the melt at high temperature through the following ways: Direct dissolution: When molten metal (such as titanium and aluminum) contacts graphite, carbon dissolves in the form of atoms (for example, the solubility of carbon in titanium can reach more than 0.2% with the increase of temperature), forming a hard and brittle phase (such as TiC), which significantly reduces the plasticity of the material.

[0021] Sublimation pollution: In a vacuum environment (especially when the vacuum degree < 10 -3 Pa), the surface atoms of graphite sublime and deposit on the surface of the molten pool, or form carbon particle inclusions.

[0022] Reaction products: If there is residual water vapor or oxygen in the furnace, graphite reacts with oxygen to generate CO / CO2. CO decomposes into C and O at high temperature, exacerbating the carbon-oxygen double pollution.

[0023] The oxidation threshold of the graphite electrode is low: Graphite undergoes obvious oxidation (generating CO) above 600 °C when the vacuum degree < 10 -2 Pa or contains trace amounts of oxygen, resulting in loose electrode surface and increased resistivity.

[0024] Therefore, the present invention proposes to adopt a combination of high-pressure pulsed inert gas purging and low-pressure continuous microflow (such as high-pressure argon, flow rate 5 L / min, 7 L / min or 10 L / min, pulse interval 1 s, 3 s or 5 s) to form an air curtain at the electrode end, inhibit the diffusion of sublimated carbon particles to the molten pool, and at the same time isolate trace amounts of oxygen to prevent oxidation.

[0025] Specifically, to achieve low-air-consumption continuous sealing, the pressure of the high-pressure inert gas is 1.5 bar - 2.5 bar, the pressure of the low-pressure inert gas is 0.5 bar, 0.8 bar or 1.2 bar, and the high-pressure frequency f of the pulsed gas supply parameters H is 5 Hz, 7 Hz or 10 Hz, and the high-pressure duty cycle D H is 60%, 65% or 70%. The high-pressure inert gas continuously flows microscopically to reach a quasi-steady gas curtain, while the average gas flow rate is reduced by more than 30% compared to the continuous input. Different effects are achieved by changing the high-pressure frequency, high-pressure duty cycle, low-pressure frequency and phase difference of the pulsed gas supply parameters, as shown in Table 1.

[0026]

[0027] Table 1 Pulsed gas supply can achieve periodic strengthening, dynamic sealing or oscillating mixing of the gas curtain through the coordinated adjustment of frequency, duty cycle and phase difference.

[0028] As an embodiment of the present invention, a conical diversion part 7 is provided at the bottom of the cylindrical protective shell, and a spiral diversion groove 8 is provided on the inner wall of the conical diversion part. The conical diversion part generates local negative pressure through the Venturi effect, enhancing the aggregation effect of the gas curtain towards the end of the electrode. The spiral diversion groove guides the air flow to form a spiral aggregation.

[0029] As a preferred example of the present invention, as Figures 1 - 2 shown, a third gas pipeline 9 is connected between the cylindrical protective shell and the side wall of the furnace body, and the third gas pipeline is used to output inert gas. To facilitate the regulation and recovery of inert gas, an air extraction pump 10 connected to the third gas pipeline is installed outside the furnace body. When it is necessary to extract the inert gas in the furnace body, the air extraction pump is started to extract the high-pressure inert gas and low-pressure inert gas from the third gas pipeline.

[0030] By adjusting parameters such as the pressure, outlet angle, pipe diameter, and position of the first gas pipeline, the intensity, direction, coverage range, and stability of the gas curtain can be effectively controlled. For example: 1. Pressure: As the flow rate increases, the momentum is significantly enhanced, the penetration ability and directivity of the gas curtain are enhanced, and a more stable and longer-distance high-speed flow area can be formed (the length and intensity of the gas curtain increase↑). If the pressure is too high, it may cause the jet to excessively entrain the low-pressure air flow, thickening the boundary layer of the gas curtain (intensifying mixing). When the flow rate decreases, the momentum weakens, the gas curtain is easily disturbed by the low-pressure air flow, and even "pushed away", resulting in the fragmentation or reduction of the gas curtain range. 2. The increase of the axial (downward) velocity component increases the downward extension distance of the gas curtain↑, enhances the entrainment effect on the low-pressure air flow, and the gas curtain is more biased towards the lower part of the cavity, which is suitable for scenarios where bottom drainage needs to be strengthened. As Figure 3As shown in the figure, it can be achieved through a drainage component. Specifically, a ring-shaped base 11 is rotatably connected to the top of the furnace body between the cylindrical protective shell and the graphite electrode. The bottom of the ring-shaped base extends downward into the baffle 12 inside the furnace body. A baffle plate 13 is provided at the bottom of the baffle to cooperate with the first gas pipeline to change the flow direction of the high-pressure inert gas. Under normal conditions, the baffle plate is staggered from the outlet of the first gas pipeline inside the cylindrical protective shell, without affecting the gas flow direction. When the outlet angle needs to be adjusted, rotate the circular base, and the baffle plate corresponds to the first gas pipeline, changing the gas flow direction to vertically downward. The range of the gas curtain is narrow and far (strong directivity). To facilitate the rotation of the circular base, a handle is provided on the ring-shaped base.

[0031] The usage method of the titanium-iron vacuum arc furnace processing device based on dynamic electrode regulation includes the following steps: input high-pressure inert gas into the first gas pipeline through an external gas source, and at the same time input low-pressure inert gas into the second gas pipeline through an external gas source. The high-pressure inert gas and the low-pressure inert gas converge and form a gas curtain on the surface and the end of the graphite electrode. The heat expansion generated by the heat in the crucible area prevents the gas curtain from continuing to extend downward and forms a balance with the gas curtain, preventing graphite oxidation and diffusion into the crucible to form pollution.

Claims

1. Titanium-iron vacuum arc furnace processing device based on dynamic electrode regulation, including: Furnace body (1); Crucible (2); graphite electrode (3); characterized in that it also includes: A cylindrical protective shell (4), the cylindrical protective shell being fixedly connected to the top of the furnace body and being located outside the graphite electrode; a first gas pipeline (5), the first gas pipeline being obliquely connected between the side wall of the furnace body and the upper part of the cylindrical protective shell, the first gas pipeline being used to introduce high-pressure inert gas; and a second gas pipeline (6), the second gas pipeline being horizontally connected between the side wall of the furnace body and the lower part of the cylindrical protective shell, the second gas pipeline being used to introduce low-pressure inert gas.

2. The titanium-iron vacuum arc furnace processing device based on dynamic electrode control according to claim 1, characterized in that: The pressure of the high-pressure inert gas is 1.5 bar-2.5 bar, and the pressure of the low-pressure inert gas is 0.5 bar-1.2 bar.

3. The titanium-iron vacuum arc furnace processing device based on dynamic electrode control according to claim 1, characterized in that: A conical flow guide portion (7) is provided at the bottom of the cylindrical protective shell, and a spiral flow guide groove (8) is provided on the inner wall of the conical flow guide portion.

4. The titanium-iron vacuum arc furnace processing device based on dynamic electrode control according to claim 1, characterized in that: The high-pressure inert gas is input in pulses, the input frequency of the high-pressure inert gas is 5-10 Hz, and the duty cycle is 60%-70%. The input of the low-pressure inert gas is continuous.

5. The titanium-iron vacuum arc furnace processing device based on dynamic electrode control according to claim 1, characterized in that: A third gas pipeline (9) is connected between the cylindrical protective shell and the side wall of the furnace body, and the third gas pipeline is used to output inert gas.

6. The titanium-iron vacuum arc furnace processing device based on dynamic electrode control as claimed in claim 5, characterized in that: An air extraction pump (10) connected to the third gas pipeline is installed outside the furnace body.

7. The titanium-iron vacuum arc furnace processing device based on dynamic electrode control according to claim 1, characterized in that: A circular ring-shaped base (11) is rotatably connected to the top of the furnace body between the cylindrical protective shell and the graphite electrode, the bottom of the circular ring-shaped base extends downward to a baffle (12) in the furnace body, and a baffle (13) is provided at the bottom of the baffle for cooperating with the first gas pipeline to change the flow direction of the high-pressure inert gas.

8. The titanium-iron vacuum arc furnace processing device based on dynamic electrode control as claimed in claim 7, characterized in that: A handle is provided on the annular base.

9. The method for using the titanium-iron vacuum arc furnace processing device based on dynamic electrode control according to any one of claims 1 to 8, characterized in that: The following steps are involved: High-pressure inert gas is input into the first gas pipeline through an external gas source, and low-pressure inert gas is input into the second gas pipeline through an external gas source. The high-pressure inert gas and the low-pressure inert gas meet and form a gas curtain at least at the end of the graphite electrode to prevent graphite oxidation and contamination.

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