CN111872408A

CN111872408A - Powder purification device

Info

Publication number: CN111872408A
Application number: CN202010844925.XA
Authority: CN
Inventors: 胡雷
Original assignee: Beijing Juti Environmental Protection Technology Co ltd
Current assignee: Beijing Juti Environmental Protection Technology Co ltd
Priority date: 2020-08-20
Filing date: 2020-08-20
Publication date: 2020-11-03

Abstract

The invention discloses a powder purifying device, and relates to the technical field of refractory metal purification. This powder purification device includes: the plasma torch comprises a main quartz tube, a fixed bin and an electromagnetic induction coil, wherein the two ends of the main quartz tube are respectively a raw material inlet end and a plasma outlet end, the fixed bin is sleeved outside the main quartz tube at intervals to form a cooling water channel, the electromagnetic induction coil comprises a coil part and a connecting part which are connected, and the connecting part is connected with the high-frequency power supply; the inlet end of the reactor is communicated with the plasma outlet end; the vacuumizing mechanism is simultaneously communicated with the tube cavity of the main quartz tube and the inner cavity of the reactor; the gas supply pipeline comprises a working gas supply pipeline, the working gas supply pipeline is communicated with the raw material inlet end to provide working gas, and the working gas is inert gas. The powder purifying device can effectively avoid powder ablation while reducing the pollution to the powder, ensure the powder yield and simultaneously ensure that the plasma torch can keep stable operation under high power.

Description

Powder purification device

Technical Field

The invention relates to the technical field of refractory metal purification, in particular to a powder purification device.

Background

Refractory metals generally refer to metals having a melting point above 1650 ℃ and a certain reserve, such as platinum, tungsten, mold, tantalum, niobium, and the like. These refractory metals are superior in high-temperature mechanical properties to low-melting-point metals such as aluminum and magnesium. Particularly, compared with common industrial materials, the high-purity refractory metal has the advantages of high plasticity, low outgassing rate, erosion resistance, good fatigue resistance, alkali metal vapor and melt corrosion resistance, good high-temperature creep property and the like. These excellent properties make them ideal candidates for high temperature structural and functional components in the fields of chemical, electronics, aerospace, nuclear, weaponry, and the like. However, if the refractory metal contains a large amount of impurity elements, such as gaseous impurity elements, other metal impurity elements, and non-metal impurity elements, the physical and chemical properties of the refractory metal are greatly adversely affected, and even the failure of the device is directly caused. Therefore, improvement of the purity of refractory metals is very important.

Among many refractory metal purification technologies, the high-frequency induction plasma technology has the advantages of no electrode pollution, large arc area, uniform temperature, capability of providing a pure heat source, no limitation on working media and the like, so the technology is increasingly applied. The basic principle for the purification of refractory metals by this technique is as follows: high-temperature plasma is generated by a plasma torch to serve as a heat source, then the powder raw material containing refractory metal is heated, and the impurity elements in the powder raw material are removed through evaporation or sublimation by utilizing the difference of vapor pressure of each impurity element in the powder raw material and the vapor pressure of the refractory metal, so that the high-purity refractory metal is obtained.

However, the powder purifying apparatus currently using the high-frequency induction plasma technology generally has the following problems: 1. in order to reduce the pollution to the powder, the vacuum degree of the device during starting can be too high, but the powder ablation phenomenon is easy to occur at the moment, so that the powder obtaining rate is influenced; 2. in the plasma torch, because the quartz tube is usually cooled only by a layer of working gas near the inner wall of the quartz tube, the cooling effect depends on the gas amount of the working gas, the effect is unstable, the quartz tube is possibly burnt by high-temperature plasma flame flow, the stable operation of the plasma torch under high power is not facilitated, and the obtaining of the final powder product is also influenced. Due to the above problems, the large-scale application of the high temperature plasma technology for the purification of refractory metals is limited.

Accordingly, a powder purifying apparatus is needed to solve the above problems.

Disclosure of Invention

The invention aims to provide a powder purifying device, which can effectively avoid powder ablation when pollution to powder is reduced, ensure the powder obtaining rate, simultaneously ensure that a plasma torch can keep stable operation under high power and is beneficial to large-scale application of high-temperature plasma technology for purifying refractory metals.

In order to achieve the purpose, the invention adopts the following technical scheme:

a powder purifying apparatus comprising:

the plasma torch comprises a main quartz tube, a fixed bin and an electromagnetic induction coil, wherein two ends of the main quartz tube are respectively a raw material inlet end and a plasma outlet end, the fixed bin is sleeved outside the main quartz tube at intervals to form a cooling water channel, the cooling water channel is provided with a cooling water inlet and a cooling water outlet, the electromagnetic induction coil comprises a coil part and a connecting part connected to the end part of the coil part, the coil part is wound outside the main quartz tube and is positioned in the fixed bin, and the connecting part extends out of the fixed bin and is connected with the high-frequency power supply;

the inlet end of the reactor is communicated with the plasma outlet end;

the vacuumizing mechanism is simultaneously communicated with the tube cavity of the main quartz tube and the inner cavity of the reactor;

and the gas supply pipeline comprises a working gas supply pipeline, the working gas supply pipeline is communicated with the raw material inlet end of the main quartz tube to provide working gas, and the working gas is inert gas.

Optionally, the plasma torch further comprises an inner quartz tube spacedly nested inside the main quartz tube to form a cooling gas channel, and the inner quartz tube is disposed at the raw material inlet end of the plasma torch.

Optionally, follow the circumference of coil portion the coil portion is outside be provided with the thermal radiation shielding board in the fixed storehouse, just the thermal radiation shielding board sets up to hollow structure be provided with shield panel cooling water inlet and shield panel cooling water outlet on the thermal radiation shielding board, shield panel cooling water inlet with shield panel cooling water outlet all with the cavity of thermal radiation shielding board is linked together.

Optionally, the powder purifying device further comprises a powder feeding mechanism, the powder feeding mechanism comprises a pneumatic conveying pipeline, a carrier gas inlet and a gas-powder mixture outlet are formed at two ends of the pneumatic conveying pipeline respectively, the gas-powder mixture outlet is communicated with the raw material inlet end of the main quartz tube, a tube section of the gas-powder mixture outlet in the pneumatic conveying pipeline is a venturi tube section, and a powder inlet is formed in the pneumatic conveying pipeline between the carrier gas inlet and the gas-powder mixture outlet;

the gas supply line further comprises a carrier gas supply line which is communicated with the carrier gas inlet to provide carrier gas, and the carrier gas is inert gas.

Optionally, the powder feeding mechanism further comprises:

the discharging hopper is used for discharging the powder raw material;

the inlet end of the powder feeding pipeline is communicated with the outlet end of the blanking hopper, and the outlet end of the powder feeding pipeline is communicated with the powder inlet;

and the screw rod is arranged in the powder conveying pipeline to convey the powder raw material.

Optionally, powder feeding mechanism still includes the storage hopper, storage has in the storage hopper the powder raw materials, the upper portion of storage hopper is provided with purge gas inlet, protective gas inlet and gas vent, purge gas inlet with carrier gas supply pipeline intercommunication, the export of storage hopper bottom through sealed pipeline with the entrance point intercommunication of hopper down.

Optionally, the vacuum pumping mechanism comprises a first vacuum pump and a second vacuum pump, and the pumping end of the first vacuum pump is simultaneously communicated with the cavity of the main quartz tube and the inner cavity of the reactor, so that the vacuum degree in the cavity of the main quartz tube and the vacuum degree in the inner cavity of the reactor are both reduced to be below a first preset vacuum degree before the plasma torch is ignited;

and the air exhaust end of the second vacuum pump is communicated with the inner cavity of the reactor so as to reduce the vacuum degree in the inner cavity of the reactor to be below a second preset vacuum degree after the plasma torch is ignited, and the second preset vacuum degree is higher than the first preset vacuum degree.

Optionally, the powder purifying device further comprises a powder collecting mechanism, and the powder collecting mechanism is arranged at the bottom of the reactor and communicated with the outlet end of the reactor to collect the purified powder.

Optionally, the powder purifying apparatus further includes:

the condenser is communicated with the inner cavity of the reactor through the side wall of the reactor so as to cool the gas flowing out of the reactor;

the gas-solid separation mechanism is arranged at the downstream of the condenser along the outflow direction of the gas so as to remove solid particles in the gas;

and the gas-liquid separation mechanism is arranged at the downstream of the gas-solid separation mechanism along the outflow direction of the gas so as to remove the liquid component in the gas.

Optionally, the powder purification device further comprises a temperature measurement mechanism, the temperature measurement mechanism comprises a driving part and a temperature measurement probe, and the output end of the driving part is in transmission connection with the temperature measurement probe so as to drive the temperature measurement probe to extend into the inner cavity of the reactor to detect the temperature of the plasma flame.

The invention has the beneficial effects that:

the invention provides a powder purifying device, which can introduce working gas into a plasma torch and a reactor through a gas supply pipeline after a main quartz tube and the reactor in the plasma torch are pumped to a certain vacuum degree by a vacuum pumping mechanism. Because the working gas is inert gas, the device does not need to keep overhigh vacuum degree, powder in the plasma torch or the reactor can be effectively prevented from being polluted, powder ablation can be effectively prevented, and the powder obtaining rate is ensured. Meanwhile, when the plasma torch operates, cooling water is introduced into the cooling water channel through the cooling water inlet, and the cooled cooling water flows out from the cooling water outlet, so that the main quartz tube can be continuously cooled by using circulating cooling water, the plasma torch can keep stable operation under high power, the final powder product is ensured to be obtained, and the large-scale application of purifying refractory metals by using a high-temperature plasma technology is facilitated.

Drawings

Fig. 1 is a schematic view of an overall structure of a powder purifying apparatus according to an embodiment of the present invention;

fig. 2 is a schematic view of an overall structure of a powder feeding mechanism in the powder purifying apparatus according to the embodiment of the present invention;

fig. 3 is a partially enlarged view of a powder feeding mechanism in the powder purifying apparatus according to the embodiment of the present invention;

fig. 4 is a schematic front view of a plasma torch in a powder purification apparatus according to an embodiment of the present invention;

fig. 5 is a schematic top view of a plasma torch in the powder purifying apparatus according to an embodiment of the present invention.

In the figure:

1. a powder feeding mechanism; 11. a storage hopper; 111. a purge gas inlet; 112. a shielding gas inlet; 113. an exhaust port; 12. feeding a hopper; 13. a powder feeding pipeline; 14. a screw rod; 15. a pneumatic conveying pipeline; 151. a carrier gas inlet; 152. a powder inlet; 153. an air-powder mixture outlet; 154. shrinking the pipe section; 155. expanding the pipe section; 16. a drive motor; 17. a powder feeding gun; 171. a powder feeding gun cooling water inlet; 172. a powder feeding gun cooling water outlet;

2. a plasma torch; 21. a main quartz tube; 22. an inner quartz tube; 23. fixing the bin; 24. an electromagnetic induction coil; 241. a coil section; 242. a connecting portion; 243. a coil cooling water inlet; 244. a coil cooling water outlet; 25. a thermal radiation shield plate; 251. a first arc-shaped plate; 2511. a shield plate cooling water inlet; 252. a second arc-shaped plate; 2521. a shield plate cooling water outlet; 253. a connecting pipe; 26. a cooling gas channel; 27. a cooling water passage; 271. a cooling water inlet; 272. a cooling water outlet;

3. a high frequency power supply; 4. a cooling water circulation mechanism; 5. a reactor; 6. a powder collecting mechanism; 7. a condenser; 8. a gas-solid separation mechanism; 9. a gas-liquid separation mechanism;

10. a first vacuum pump; 20. a water pump; 30. a second vacuum pump; 40. a valve train; 41. a carrier gas supply line; 42. a working gas supply line; 50. a temperature measuring mechanism; 60. a PLC controller.

Detailed Description

In order to make the technical problems solved, the technical solutions adopted and the technical effects achieved by the present invention clearer, the technical solutions of the present invention are further described below by way of specific embodiments with reference to the accompanying drawings.

In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

In the description of the present embodiment, the terms "upper", "lower", "left", "right", and the like are used based on the orientations and positional relationships shown in the drawings only for convenience of description and simplification of operation, and do not indicate or imply that the referred device or element must have a specific orientation, be configured and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used only for descriptive purposes and are not intended to have a special meaning.

The embodiment provides a powder purification device. As shown in fig. 1, the powder purifying apparatus includes a plasma torch 2, a high-frequency power supply 3, a reactor 5, a vacuum-pumping mechanism, and an air supply line. The plasma torch 2 comprises a main quartz tube 21, a fixed bin 23 and an electromagnetic induction coil 24, two ends of the main quartz tube 21 are respectively a raw material inlet end and a plasma outlet end, the fixed bin 23 is sleeved outside the main quartz tube 21 at intervals to form a cooling water channel 27, the cooling water channel 27 is provided with a cooling water inlet 271 and a cooling water outlet 272, the electromagnetic induction coil 24 comprises a coil part 241 and a connecting part 242 connected to the end part of the coil part 241, the coil part 241 is wound outside the main quartz tube 21 and located in the fixed bin 23, and the connecting part 242 extends out of the fixed bin 23 and is connected with a high-frequency power supply 3. The inlet end of the reactor 5 is in communication with the plasma outlet end. The vacuumizing mechanism is simultaneously communicated with the cavity of the main quartz tube 21 and the inner cavity of the reactor 5 so as to vacuumize the cavity of the main quartz tube 21 or the inner cavity of the reactor 5. The gas supply line includes a working gas supply line 42, the working gas supply line 42 is in communication with the raw material inlet end of the main quartz tube 21 to supply a working gas, and the working gas is an inert gas.

On the one hand, after the main quartz tube 21 and the reactor 5 are evacuated to a certain degree of vacuum by the evacuation mechanism, the working gas can be introduced into the main quartz tube 21 and the reactor 5 through the gas supply line. Because the working gas is inert gas, the powder entering the plasma torch 2 or the reactor 5 can be effectively prevented from being polluted without keeping the device in an overhigh vacuum degree. Meanwhile, because the ultrahigh vacuum degree does not need to be maintained, the powder ablation can be effectively avoided, and the powder yield is ensured.

On the other hand, when the plasma torch 2 is in operation, the cooling water is introduced into the cooling water channel 27 through the cooling water inlet 271, and the cooled cooling water flows out from the cooling water outlet 272, so that the main quartz tube 21 can be continuously cooled by using the circulating cooling water, the main quartz tube 21 is more effectively prevented from being burnt by the high-temperature plasma flame flow, and the plasma torch 2 can be kept in stable operation under high power.

In this embodiment, the interval between the fixed bin 23 and the main quartz tube 21 is not less than 10mm, so that a sufficient amount of circulating cooling water can be introduced into the cooling water channel 27 to ensure the cooling effect. Further, as shown in fig. 1, a cooling water circulation mechanism 4 is provided in the powder purifying apparatus to provide circulating cooling water and to lower the temperature of the heated circulating cooling water.

Optionally, to enhance the cooling effect, as shown in fig. 4, the plasma torch 2 further comprises an inner quartz tube 22, the inner quartz tube 22 is nested at intervals inside the main quartz tube 21 to form a cooling gas channel 26, and the inner quartz tube 22 is disposed at the raw material inlet end of the plasma torch 2. At this time, part of the working gas may enter the main quartz tube 21 through the cooling gas passage 26, and better adhere to the inner wall of the main quartz tube 21 to cool the main quartz tube 21. In this embodiment, the upper end of the main quartz tube 21 is the working gas inlet end, and the inner quartz tube 22 is disposed therein. When the working gas in the cooling gas passage 26 flows out, the working gas can also flow into the middle portion of the main quartz tube 21, and is used for generating plasma.

Optionally, the fixed bin 23 is a transparent quartz bin, so that an operator can observe the flowing state of the cooling water in the cooling water channel 27 conveniently, and the normal operation of the water cooling process is ensured. Further, an electromagnetic induction coil 24 is integrated with the transparent quartz capsule for ease of use. In this embodiment, the transparent quartz chamber is formed by pouring quartz glass, and is integrally disposed with the electromagnetic induction coil 24.

Alternatively, as shown in fig. 4, the electromagnetic induction coil 24 is provided as a hollow structure. Specifically, a coil cooling water inlet 243 and a coil cooling water outlet 244 are provided on the electromagnetic induction coil 24, and both the coil cooling water inlet 243 and the coil cooling water outlet 244 are communicated with the hollow cavity of the electromagnetic induction coil 24. At this time, the circulating cooling water can be introduced into the hollow cavity of the electromagnetic induction coil 24, so that the main quartz tube 21 and the fixed bin 23 are cooled to a certain degree at the same time, and the service life of the equipment is prolonged.

Alternatively, in order to effectively prevent the heat generated in the plasma torch 2 from radiating to the surrounding environment, as shown in fig. 4 and 5, a heat radiation shield plate 25 is provided in the fixed bin 23 outside the coil portion 241 along the circumferential direction of the coil portion 241. In this embodiment, the thermal radiation shielding plate 25 is configured as a hollow structure, the thermal radiation shielding plate 25 is provided with a shielding plate cooling water inlet 2511 and a shielding plate cooling water outlet 2521, and the shielding plate cooling water inlet 2511 and the shielding plate cooling water outlet 2521 are both communicated with the hollow cavity of the thermal radiation shielding plate 25. At this time, circulating cooling water can be introduced into the hollow cavity of the heat radiation shielding plate 25, the fixed bin 23 is continuously cooled by the circulating cooling water, and the service life of the fixed bin 23 is effectively prolonged.

In a specific structure, the thermal radiation shielding plate 25 includes a first arc-shaped plate 251 and a second arc-shaped plate 252, and the first arc-shaped plate 251 and the second arc-shaped plate 252 are relatively spaced at two sides of the coil portion 241 so as to prevent interference with the arrangement of the connecting portion 242 in the electromagnetic induction coil 24 while playing a thermal radiation shielding role. Further, a shield plate cooling water inlet 2511 is provided on the first arc plate 251, and a shield plate cooling water outlet 2521 is provided on the second arc plate 252. And a connection pipe 253 is further provided in the thermal radiation shielding plate 25 to connect the hollow cavity of the first arc-shaped plate 251 and the hollow cavity of the second arc-shaped plate 252, thereby ensuring the circulation of cooling water.

Optionally, the powder purifying apparatus further comprises a powder feeding mechanism 1 for facilitating the feeding of the powder raw material required for the purification of the refractory metal. As shown in fig. 1-3, the powder feeding mechanism 1 includes a pneumatic conveying pipeline 15, a carrier gas inlet 151 and a gas-powder mixture outlet 153 are respectively formed at two ends of the pneumatic conveying pipeline 15, and the gas-powder mixture outlet 153 is communicated with the raw material inlet end of the main quartz tube 21. And a powder inlet 152 is arranged on the pneumatic conveying pipeline 15 between the carrier gas inlet 151 and the gas-powder mixture outlet 153. The gas supply line further includes a carrier gas supply line 41, the carrier gas supply line 41 communicates with the carrier gas inlet 151 to supply a carrier gas, and the carrier gas is an inert gas. In this embodiment, the working gas and the carrier gas are argon gas.

Optionally, as shown in fig. 2, at the carrier gas inlet 151 in the pneumatic conveying pipe 15, a carrier gas nozzle is further provided to connect the carrier gas supply line 41. Furthermore, a throttling structure is arranged in the carrier gas nozzle to accelerate the carrier gas to flow and form supersonic fluid, so that the carrier gas and the powder raw material are mixed more uniformly.

At this time, the powder raw material is fed into the pneumatic conveying pipe 15 through the powder inlet 152, mixed with the carrier gas in the pneumatic conveying pipe 15, and further flowed to the outlet of the pneumatic conveying pipe 15 (i.e., the gas-powder mixture outlet 153) with the carrier gas, and finally fed into the plasma torch 2. It can be understood that, because the carrier gas is an inert gas, the powder raw material can be effectively prevented from being polluted in the conveying process.

In this embodiment, the pipe section at the outlet 153 of the gas-powder mixture in the pneumatic conveying pipeline 15 is a venturi pipe section. Under the action of the venturi tube section, negative pressure can be formed at the outlet of the pneumatic conveying pipeline 15 to generate strong adsorption force, so that the backflow of the powder raw materials can be effectively avoided, the flowing of the carrier gas can be accelerated, and the mixing effect of the carrier gas and the powder raw materials can be effectively enhanced.

Specifically, as shown in fig. 2, the venturi section includes a contraction pipe section 154 and an expansion pipe section 155 arranged in this order in the flow direction of the carrier gas. Optionally, the converging tube section 154 and the diverging tube section 155 are removably coupled to facilitate cleaning of the device.

Optionally, as shown in fig. 2, the powder feeding mechanism 1 further includes a lower hopper 12, a powder feeding pipe 13 and a screw 14. Wherein, the blanking hopper 12 is used for blanking the powder raw material. The inlet end of the powder feeding pipe 13 is communicated with the outlet end of the lower hopper 12, and the outlet end of the powder feeding pipe 13 is communicated with the powder inlet 152. A screw 14 is provided in the powder feeding duct 13 to feed the powder raw material. Through the cooperation between hob 14 and the powder feeding pipeline 13, the closed transportation of powder raw materials can be conveniently realized, and hob 14 operates steadily, can effectively prevent powder raw materials from piling up. In this embodiment, the powder feeding pipe 13 and the screw rod 14 are both horizontally arranged to further ensure the uniformity and stability of feeding.

Further, the outlet direction of the outlet end of the powder feeding pipeline 13 is arranged along the gravity direction, so that the powder raw material can fall into the pneumatic conveying pipeline 15 under the action of gravity.

In this embodiment, the outlet end of the discharging hopper 12 and the inlet end of the powder feeding pipe 13 and the outlet end of the powder feeding pipe 13 and the powder inlet 152 of the pneumatic conveying pipe 15 are connected by sealing pipelines, so as to prevent the powder raw material from leaking, effectively reduce the contact between the powder raw material and the outside, and reduce the pollution to the powder raw material as much as possible.

Optionally, as shown in fig. 2, the powder feeding mechanism 1 further includes a driving motor 16, and an output end of the driving motor 16 is in transmission connection with the screw 14 to drive the screw 14 to rotate.

Optionally, as shown in fig. 2, the powder feeding mechanism 1 further includes a storage hopper 11, and the powder raw material is stored in the storage hopper 11. The upper part of the storage hopper 11 is provided with a purge gas inlet 111, a shielding gas inlet 112 and an exhaust port 113, the purge gas inlet 111 is communicated with the carrier gas supply pipeline 41, and an outlet at the bottom of the storage hopper 11 is communicated with the inlet end of the blanking hopper 12 through a sealing pipeline.

At this time, the carrier gas is introduced into the storage hopper 11 through the carrier gas supply line 41 to purge, thereby forming an inert atmosphere. Then, the shielding gas can be introduced into the storage hopper 11 through the shielding gas inlet 112, so as to further prevent the powder raw material in the storage hopper 11 from being polluted.

Optionally, as shown in fig. 1 and 2, the powder feeding mechanism 1 further includes a powder feeding gun 17. The inlet end of the powder feeding gun 17 is communicated with the gas-powder mixture outlet 153 on the pneumatic conveying pipeline 15, and the outlet end of the powder feeding gun 17 is communicated with the raw material inlet end of the plasma torch 2, so that powder raw materials can be introduced into the plasma torch 2 more conveniently.

Further, the powder feeding gun 17 is made of a high temperature resistant metal, and a jacket is provided thereon. The jacket is provided with a powder feeding gun cooling water inlet 171 and a powder feeding gun cooling water outlet 172 for cooling by circulating cooling water. Specifically, the cooling water introduced into the jacket needs to be pressurized to more than 1.7MPa to ensure that the cooling water has a sufficiently high flow rate for rapid cooling and to avoid gasification of the jacket.

Alternatively, as shown in fig. 1, the vacuum mechanism includes a first vacuum pump 10 and a second vacuum pump 30. The air exhaust end of the first vacuum pump 10 is communicated with the tube cavity of the main quartz tube 21 and the inner cavity of the reactor 5, so that the vacuum degree in the two chambers is reduced to be lower than a first preset vacuum degree before the plasma torch 2 is ignited, the arcing stability is improved, and the successful ignition is ensured. In this example, the first predetermined vacuum was-100 Pa.

The air exhaust end of the second vacuum pump 30 is communicated with the inner cavity of the reactor 5 so as to reduce the vacuum degree below the second preset vacuum degree after the plasma torch 2 is ignited stably. The second preset vacuum degree is higher than the first preset vacuum degree, so that powder purification is facilitated. In this example, the second predetermined vacuum was between-21 kPa and-61 kPa (the absolute pressure value of the second predetermined vacuum was 40kPa to 80kPa, calculated from the atmospheric pressure being 101 kPa).

Alternatively, the first vacuum pump 10 is a rotary vane vacuum pump, which is compact, low in noise and low in vibration. The second vacuum pump 30 is a hydraulic ejector pump and is arranged in parallel with the rotary vane vacuum pump. A water pump 20 matched with the hydraulic jet pump is also arranged in the device. Water can be pumped into the throat of the hydrajet pump by the water pump 20 to form a stable negative pressure, and finally the required vacuum degree is obtained. Since the structures of the vane rotary vacuum pump and the hydraulic jet pump are the prior art, the detailed description is omitted. Of course, in other embodiments, the hydrajet pump may be replaced with a liquid ring vacuum pump.

Optionally, as shown in fig. 1, the powder purifying apparatus further includes a temperature measuring mechanism 50. The temperature measuring mechanism 50 includes a driving member and a temperature measuring probe. The output end of the driving piece is in transmission connection with the temperature measuring probe so as to drive the temperature measuring probe to extend into the inner cavity of the reactor 5 to detect the temperature of the plasma flame, and a favorable reference is provided for maintaining the normal operation of the system. Furthermore, after the plasma flame temperature is measured, the driving part can drive the temperature measuring probe to be quickly withdrawn, so that the temperature measuring probe is effectively prevented from being burnt.

In this embodiment, the driving member is a pneumatic cylinder. The temperature probe is a water-cooled probe, and can also effectively avoid being burnt. Furthermore, it will be appreciated that the connection between the temperature measuring mechanism 50 and the reactor 5 is sealed to avoid affecting the normal use of the reactor 5.

Optionally, the high frequency power supply 3 has a power range of 100KW-2MW and a frequency range of 0.4MHz-13.6MHz to ensure the generation of high temperature plasma.

In addition, the high-frequency power supply 3 has the following features:

(1) the oscillating part is designed into a three-loop oscillator structure, can realize wide-range power adjustment and can maintain the optimal working state of the electron tube;

(2) a single electron tube is adopted to realize power output;

(3) the structural design of an inductance coil of a grid feedback link and the configuration of a voltage-dividing capacitor of the inductance coil are as follows: firstly, the phase difference of a feedback signal and a signal on a power loop is ensured to be 90 degrees; secondly, the proportion of the voltage-dividing capacitor and the amplification factor of the electronic tube must be ensured to keep the product as a fixed value; finally, it must be ensured that the capacitance inductance of the gate link and the grounding capacitance form resonance, and the sum of the signals to ground of the link is zero.

Optionally, as shown in fig. 1, the powder purifying apparatus further includes a valve train 40. The distribution mechanism 40 is provided with a working gas source and a carrier gas source, which are connected to the gas supply pipeline and can provide the gas supply pipeline with the required working gas, carrier gas and other gases.

Optionally, in order to adjust the gas supply, as shown in fig. 1, the powder purifying apparatus further includes a PLC controller 60, and the PLC controller 60 is connected to the gas distribution mechanism 40. The supply amount and the supply time of the working gas and other gases can be adjusted through the combined action of the PLC 60 and the gas distribution mechanism 40, and the supply sequence of the working gas and carrier and other gases can also be adjusted, which is very convenient. Specifically, an electric switch valve may be provided at the outlet end of the valve train 40 to control the supply or shutoff of air. At this time, the PLC controller 60 may be connected to the electric switching valve in communication, so as to control the operation of the electric switching valve to control the gas supply.

In addition, it can be understood that the residence time of the powder raw material in the plasma torch 2 can be controlled by adjusting the gas supply, and the pressure in the ion torch 2 and the cavity of the reactor 5 can also be adjusted to meet the purification requirements of various powder raw materials.

In this embodiment, the PLC controller 60 is further connected to the high-frequency power supply 3 and the cooling water circulation mechanism 4, so as to regulate and control the operation of the high-frequency power supply 3 or the cooling water circulation mechanism 4.

Optionally, as shown in fig. 1, the powder purifying apparatus further includes a powder collecting mechanism 6. The powder collecting mechanism 6 is arranged at the bottom of the reactor 5 and is communicated with the outlet end of the reactor 5 so as to collect the purified powder. Specifically, the powder collecting mechanism 6 may be a powder collecting tank.

Optionally, as shown in fig. 1, the powder purifying apparatus further includes a condenser 7, a gas-solid separation mechanism 8, and a gas-liquid separation mechanism 9. Wherein, condenser 7 passes through the lateral wall of reactor 5 and the inner chamber intercommunication of reactor 5 to with the gaseous heat transfer of flowing out in reactor 5, cool down these gases. The gas-solid separation mechanism 8 and the gas-liquid separation mechanism 9 are arranged downstream of the condenser 7 in the gas outflow direction in sequence. When the gas flows through the gas-solid separation mechanism 8, solid particles (i.e., particles that do not enter the powder collection mechanism 6) in the gas can be effectively removed by the gas-solid separation mechanism 8. Finally, when the gas flows through the gas-liquid separation mechanism 9, the liquid component in the gas can be effectively removed by the gas-liquid separation mechanism 9.

In this embodiment, the gas outlet end of the gas-solid separation mechanism 8 is communicated with the inlet end of the gas-liquid separation mechanism 9, so that the separated gas smoothly enters the gas-liquid separation mechanism 9; the solid outlet end of the gas-solid separation mechanism 8 is communicated with an external waste collection mechanism so as to treat the separated solid particles. The gas outlet end of the gas-liquid separation mechanism 9 is communicated with the atmosphere, so that the separated gas can be discharged into the atmosphere; the liquid outlet end of the gas-liquid separation mechanism 9 communicates with an external waste collection mechanism so as to treat the separated liquid component.

Specifically, the gas-solid separation mechanism 8 may be a cyclone separator, and the gas-liquid separation mechanism 9 may be a gas-liquid separation tank. Since the structures of the cyclone separator and the gas-liquid separation tank are the prior art, the detailed description is omitted.

Specifically, when the electromagnetic induction coil 24 is connected to the high-frequency power supply 3, a changing magnetic field is generated in the main quartz tube 21, so that the working gas entering the main quartz tube 21 is ionized to generate joule heat, thereby forming a high-temperature plasma flame flow. When the powder feedstock flows through the plasma torch 2, it is melted by the high temperature plasma flame flow into droplets and enters the cavity of the reactor 5 for cooling. In the process, the impurity elements in the powder raw material can be taken away by gas in modes of evaporation, sublimation or degassing and the like, so that the purification of the refractory metal can be realized. Finally, the powder containing the purified refractory metals enters the powder collecting mechanism 6, and the gas containing impurities sequentially flows through the condenser 7, the gas-solid separation mechanism 8 and the gas-liquid separation mechanism 9 and is discharged into the atmosphere.

In addition, taking the actual power of the plasma torch 2 as 100kW as an example, compared with the prior art, because the cooling of the plasma torch 2 is effectively improved, the central temperature of the plasma torch 2 can be stabilized at 8000K-10000K, so that the powder raw material entering the plasma torch 2 can rapidly reach the molten liquid droplet state, the spheroidization rate of the formed powder particles is effectively improved, and the performance of the powder product is finally improved.

In summary, the embodiment provides a powder purifying apparatus, which sets the working gas and the carrier gas as the inert gas, and does not need to maintain an excessively high vacuum degree when the apparatus is started, so that the possibility of powder being polluted is reduced, and meanwhile, powder ablation can be effectively avoided, and the powder yield is ensured. Meanwhile, the plasma torch 2 is provided with the cooling gas channel 26 and the cooling water channel 27, so that the main quartz tube 21 can be continuously and well cooled, the plasma torch 2 can keep stable operation under high power, the final powder product is ensured to be obtained, the large-scale application of high-temperature plasma technology for purifying refractory metals is facilitated, and the practicability and the economical efficiency are high.

The above description is only a preferred embodiment of the present invention, and for those skilled in the art, the present invention should not be limited by the description of the present invention, which should be interpreted as a limitation.

Claims

1. A powder purifying apparatus, comprising:

a plasma torch (2) and a high-frequency power supply (3), wherein the plasma torch (2) comprises a main quartz tube (21), a fixed bin (23) and an electromagnetic induction coil (24), two ends of the main quartz tube (21) are respectively a raw material inlet end and a plasma outlet end, the fixed bin (23) is sleeved outside the main quartz tube (21) at intervals to form a cooling water channel (27), and a cooling water inlet (271) and a cooling water outlet (272) are arranged on the cooling water channel (27), the electromagnetic induction coil (24) includes a coil portion (241) and a connecting portion (242) connected to an end of the coil portion (241), the coil part (241) is wound outside the main quartz tube (21) and positioned inside the fixed bin (23), the connecting part (242) extends out of the fixed bin (23) and is connected with the high-frequency power supply (3);

the inlet end of the reactor (5) is communicated with the plasma outlet end;

the vacuumizing mechanism is simultaneously communicated with the tube cavity of the main quartz tube (21) and the inner cavity of the reactor (5);

and the gas supply pipeline comprises a working gas supply pipeline (42), the working gas supply pipeline (42) is communicated with the raw material inlet end of the main quartz tube (21) to provide working gas, and the working gas is inert gas.

2. Powder purification apparatus according to claim 1, wherein the plasma torch (2) further comprises an inner quartz tube (22), the inner quartz tube (22) is nested at intervals inside the main quartz tube (21) to form a cooling gas channel (26), and the inner quartz tube (22) is arranged at the raw material inlet end of the plasma torch (2).

3. The powder purifying apparatus according to claim 1, wherein a thermal radiation shielding plate (25) is disposed in the fixing chamber (23) outside the coil portion (241) along a circumferential direction of the coil portion (241), the thermal radiation shielding plate (25) is configured as a hollow structure, a shielding plate cooling water inlet (2511) and a shielding plate cooling water outlet (2521) are disposed on the thermal radiation shielding plate (25), and the shielding plate cooling water inlet (2511) and the shielding plate cooling water outlet (2521) are both communicated with a hollow cavity of the thermal radiation shielding plate (25).

4. The powder purifying device according to claim 1, further comprising a powder feeding mechanism (1), wherein the powder feeding mechanism (1) comprises a pneumatic conveying pipeline (15), a carrier gas inlet (151) and a gas powder mixture outlet (153) are respectively formed at two ends of the pneumatic conveying pipeline (15), the gas powder mixture outlet (153) is communicated with the raw material inlet end of the main quartz tube (21), a tube section of the pneumatic conveying pipeline (15) at the gas powder mixture outlet (153) is a venturi tube section, and a powder inlet (152) is arranged on the pneumatic conveying pipeline (15) between the carrier gas inlet (151) and the gas powder mixture outlet (153);

the gas supply line further comprises a carrier gas supply line (41), the carrier gas supply line (41) is communicated with the carrier gas inlet (151) to provide carrier gas, and the carrier gas is inert gas.

5. The powder purifying apparatus according to claim 4, wherein the powder feeding mechanism (1) further comprises:

a discharging hopper (12) for discharging the powder raw material;

the inlet end of the powder feeding pipeline (13) is communicated with the outlet end of the blanking hopper (12), and the outlet end of the powder feeding pipeline (13) is communicated with the powder inlet (152);

and a screw rod (14) which is arranged in the powder feeding pipeline (13) and is used for conveying the powder raw material.

6. The powder purifying apparatus according to claim 5, wherein the powder feeding mechanism (1) further comprises a storage hopper (11), the powder raw material is stored in the storage hopper (11), a purge gas inlet (111), a shielding gas inlet (112) and an exhaust port (113) are arranged at an upper portion of the storage hopper (11), the purge gas inlet (111) is communicated with the carrier gas supply pipeline (41), and an outlet at the bottom of the storage hopper (11) is communicated with an inlet end of the blanking hopper (12) through a sealing pipeline.

7. The powder purifying apparatus according to claim 1, wherein the vacuum pumping mechanism comprises a first vacuum pump (10) and a second vacuum pump (30), and the pumping end of the first vacuum pump (10) is simultaneously communicated with the tube cavity of the main quartz tube (21) and the inner cavity of the reactor (5) so as to reduce the vacuum degree in the tube cavity of the main quartz tube (21) and the inner cavity of the reactor (5) below a first preset vacuum degree before the plasma torch (2) is ignited;

and the air exhaust end of the second vacuum pump (30) is communicated with the inner cavity of the reactor (5) so as to reduce the vacuum degree in the inner cavity of the reactor (5) to be below a second preset vacuum degree after the plasma torch (2) is ignited, and the second preset vacuum degree is higher than the first preset vacuum degree.

8. The powder purifying apparatus according to any one of claims 1 to 7, further comprising a powder collecting mechanism (6), wherein the powder collecting mechanism (6) is disposed at the bottom of the reactor (5) and is communicated with an outlet of the reactor (5) to collect the purified powder.

9. The powder purifying apparatus according to any one of claims 1 to 7, further comprising:

the condenser (7) is communicated with the inner cavity of the reactor (5) through the side wall of the reactor (5) so as to cool the gas flowing out of the reactor (5);

the gas-solid separation mechanism (8) is arranged at the downstream of the condenser (7) along the flowing-out direction of the gas so as to remove solid particles in the gas;

and the gas-liquid separation mechanism (9) is arranged at the downstream of the gas-solid separation mechanism (8) along the outflow direction of the gas so as to remove the liquid component in the gas.

10. The powder purifying device according to any one of claims 1 to 7, further comprising a temperature measuring mechanism (50), wherein the temperature measuring mechanism (50) comprises a driving member and a temperature measuring probe, and an output end of the driving member is in transmission connection with the temperature measuring probe to drive the temperature measuring probe to extend into an inner cavity of the reactor (5) to detect the temperature of the plasma flame.