Preparation process of high-purity cadmium powder

Abstract

The application discloses a high-purity cadmium powder preparation process and relates to the technical field of metal powder manufacturing. The high-purity cadmium powder preparation process comprises the following steps: S1, charging: after impurity secondary purging and cleaning of 6N cadmium raw material purified by distillation, the cadmium raw material is charged into a clean quartz crucible, the quartz crucible is placed into a vertical pulling furnace and the furnace door is sealed, a high-temperature-resistant sealing gasket is additionally arranged at the sealed part of the furnace door to improve the initial sealing performance. When the high-purity cadmium powder is prepared by using a gas atomization powder preparation machine, the cadmium liquid is first broken by using high-temperature gas, then the rotating pipe is driven to rotate by a first driving module, and the partition cover is driven to rotate, so that the high-temperature broken cadmium liquid can sequentially enter multiple cooling zones for partitioned rapid cooling and solidification, the cadmium liquid has more sufficient time to form regular spherical shapes under the action of surface tension, the atomized powder particles can be dispersed, the agglomeration phenomenon between the particles is reduced, and the powder preparation quality can be improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of metal powder manufacturing, in particular to a high-purity cadmium powder preparation process. BACKGROUND

[0002] The high-purity cadmium powder belongs to metal powder and has key applications in the fields of semiconductors, photoelectric materials and electronic devices due to high purity and large specific surface area. The preparation of the high-purity cadmium powder mainly includes charging, vacuum treatment, leak detection, pressure regulation, material melting, stabilization, crystal initiation, shoulder forming, equal-diameter forming, finishing, furnace stopping and powder making. In the powder making, a gas atomization powder making machine is usually used for powder making operation. In the preparation, cadmium raw material (for example, high-purity cadmium crystal obtained by the Czochralski method) is heated to complete melting in a melting chamber to form a uniform cadmium liquid. Then, the cadmium liquid is poured into a tundish and flows out to an atomization chamber through a flow guide nozzle. Normal temperature inert gas is sprayed out through a nozzle. Under the protection of a nitrogen atmosphere, the cadmium liquid is broken into small droplets by high-speed airflow. The droplets are rapidly cooled and solidified in the flight process to form powder particles. After screening, spherical or approximately spherical cadmium powder is obtained.

[0003] However, in the use of the existing gas atomization powder making machine, normal temperature inert gas is sprayed out through a nozzle to realize the breaking and cooling operation of the cadmium liquid to form cadmium powder. However, the cooling speed is fast when the normal temperature gas breaks the cadmium liquid, and the droplets are easily solidified before being fully spheroidized, which leads to irregular powder morphology and affects the quality of powder making. In addition, the cadmium powder particles after cooling are prone to agglomeration, which also affects the quality of powder making. SUMMARY

[0004] The purpose of the present application is to provide a high-purity cadmium powder preparation process which first breaks the cadmium liquid with high-temperature gas and then rapidly cools and solidifies the cadmium liquid droplets in different zones when preparing high-purity cadmium powder by using a gas atomization powder making machine, so as to solve the problems of easy solidification of cadmium liquid droplets before being fully spheroidized and easy agglomeration between cadmium powder particles after cooling.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a high-purity cadmium powder preparation process, comprising the following steps:

[0006] S1: charging: accurately weighing 2.5 kg of 6N cadmium raw material purified by distillation, and charging into a clean quartz crucible after impurity secondary purging and cleaning. The quartz crucible is placed in a Czochralski furnace and the furnace door is sealed. A high-temperature sealing gasket is installed at the sealing part of the furnace door to improve the initial sealing performance.

[0007] S2: vacuum treatment: the Czochralski furnace is subjected to staged vacuumizing. First, vacuumizing to 10 Pa for 10 min, then continuing to vacuumize to 0.1 Pa for 30 min to ensure that the air in the furnace is fully discharged.

[0008] S3: Leak detection: The sealing of the Czochralski furnace was detected by a helium mass spectrometer leak detector;

[0009] S4: Pressure regulation: High-purity argon was filled into the furnace in two times, first to 0.1 MPa for 5 min, then to 0.25 MPa, to ensure uniform and stable argon atmosphere in the furnace;

[0010] S5: Material melting: Ladder type temperature rising was adopted, first to 300℃ for 15 min, then to above the melting point of cadmium (about 321℃) and kept for a while until the material was completely melted to avoid local overheating leading to oxidation of raw materials;

[0011] S6: Stabilization: The temperature was accurately and constantly controlled at 450℃ with a temperature control accuracy of ±2℃, and the holding time was extended to 60 min to ensure uniformity of cadmium liquid composition and temperature;

[0012] S7: Crystal seeding: Directional seed crystal was selected for Czochralski crystal seeding, and the seeding rate was controlled at 5-8 mm / h to ensure stable combination of crystal seed and melt interface;

[0013] S8: Shoulder growth: The crystal shoulder growth was controlled at a rate of 3-5 mm / h, and the shoulder angle was controlled at 12°-15° to avoid stress cracks in the crystal;

[0014] S9: Constant diameter: The crystal growth was carried out at a constant diameter growth rate of 4-6 mm / h while maintaining a constant temperature of 450℃, and the crystal diameter was monitored in real time with a deviation controlled within ±0.5 mm;

[0015] S10: Finishing: The crystal was finished by gradually reducing the pulling rate to 1-2 mm / h, and then the temperature was lowered to 350℃ before further cooling to obtain high-purity cadmium crystal;

[0016] S11: Furnace shutdown: The heater was turned off, and the temperature was lowered in stages, first to 200℃, then argon was introduced to assist cooling to room temperature to prevent defects in the crystal due to sudden cooling;

[0017] S12: Powder making: The Czochralski purified cadmium was treated by removing the surface oxidation layer and then put into a gas atomization powder making machine to make high-purity cadmium powder;

[0018] The gas atomization powder making machine comprises a device main body; the device main body comprises a shell, a partition plate connected with the shell, and a smelting chamber and an atomization chamber between the shell and the partition plate; the device main body further comprises a tundish arranged in the smelting chamber and a flow guide nozzle communicating the tundish with the atomization chamber; the device main body further comprises a gas nozzle connected with the partition plate, a first gas inlet pipe communicating with the gas nozzle, and a gas return pipe communicating with the atomization chamber; the device main body further comprises an electric heating ring connected to the side wall of the first gas inlet pipe; the device main body further comprises a rotary cooling mechanism for partition cooling and solidification of the broken cadmium liquid;

[0019] The rotating cooling mechanism comprises a rotating pipe rotating in the atomizing chamber, a plurality of partition covers communicated with the rotating pipe, and a plurality of rectangular covers communicated with the partition covers; two adjacent partition covers form a cooling area; the rotating cooling mechanism further comprises a blowing mechanism arranged in each cooling area for blowing and cooling the broken cadmium liquid; the rotating pipe and the partition covers are filled with cooling liquid; the rotating cooling mechanism further comprises a circulating mechanism for circulating the cooling liquid in the rotating pipe and a first driving module for driving the rotating pipe to rotate.

[0020] Preferably, the blowing mechanism comprises a plurality of gas supply pipes connected in the rotating pipe, a first connecting pipe communicated with the gas supply pipes, and a jet pipe communicated with the first connecting pipe; the gas supply pipes are arranged through the end of the rotating pipe; the first connecting pipe is inserted in the rectangular cover; the jet pipe is arranged through the rectangular cover; the blowing mechanism further comprises a gas supply mechanism for supplying gas into the gas supply pipe.

[0021] Preferably, the gas supply mechanism comprises a second air inlet pipe connected with the housing, a first annular cover communicated with the second air inlet pipe, and a rotating disc rotating in the first annular cover; the rotating disc is fixedly sleeved on the side wall of the gas supply pipe; the gas supply mechanism further comprises a semicircular plate connected with the first annular cover; the semicircular plate can movably seal the gas supply pipe.

[0022] Preferably, the circulating mechanism comprises a heat exchange cover connected with the first air inlet pipe, two second annular covers rotating on the side wall of the rotating pipe, and a second connecting pipe communicated between the second annular covers and the heat exchange cover; the second annular covers are communicated with the rotating pipe through first through holes; the circulating mechanism further comprises a circulating pump connected with the second connecting pipe and a temperature sensor connected on the first air inlet pipe.

[0023] Preferably, the device body further comprises a rotating mechanism for driving the gas nozzle to rotate; the rotating mechanism comprises an annular groove opened in the bottom of the partition plate, a rotating cover rotationally connected with the annular groove, and a first driving assembly for driving the rotating cover to rotate; the rotating cover is communicated with the annular groove through a second through hole; the annular groove is communicated with the first air inlet pipe; the rotating cover comprises a conical surface; the gas nozzle is connected with the conical surface and communicated with the inside of the rotating cover.

[0024] Preferably, the first driving assembly comprises a driven bevel gear connected with the rotating cover, a driving bevel gear meshing with the driven bevel gear, and a rotating rod connected between the driving bevel gear and the partition plate; the first driving assembly further comprises a driven pulley connected with the rotating rod, a double-groove pulley connected with the rotating pipe, and a belt connected between the driven pulley and the double-groove pulley.

[0025] Preferably, the device body further comprises a collecting mechanism for collecting high-purity cadmium powder; the collecting mechanism comprises a rotating filter cylinder rotating at the bottom of the atomizing chamber and a second driving assembly for driving the rotating filter cylinder to rotate; the rotating filter cylinder comprises a conical filter hopper and a discharge valve connected to the bottom of the conical filter hopper; the discharge valve is connected to the bottom of the shell.

[0026] Preferably, the second driving assembly comprises a worm gear connected to the rotating filter cylinder, a worm connected to the worm gear, and a rotating shaft connected between the worm and the shell; the second driving assembly further comprises a second driving module for driving the rotating shaft to rotate.

[0027] Preferably, the collecting mechanism further comprises a cleaning mechanism for cleaning the rotating filter cylinder; the cleaning mechanism comprises a scraper connected to the inner wall of the shell; the scraper comprises a vertical plate; the cleaning mechanism further comprises a moving frame, a rubber column connected to the moving frame, and a moving assembly for driving the moving frame to move back and forth.

[0028] Preferably, the moving assembly comprises a push block, a connecting rod connected between the push block and the moving frame, and a spring telescopic rod connected between the moving frame and the shell; the moving assembly further comprises a cam connected to the rotating shaft, so that the push block can slide along the side wall of the cam.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] The high-purity cadmium powder preparation process sets a rotating cooling mechanism, etc. When using a gas atomization powder preparation machine to prepare high-purity cadmium powder, the inert gas entering the first gas inlet pipe is first heated by the electric heating ring, and the high-temperature gas is sprayed out through the gas nozzle to break the cadmium liquid. Then, the rotating pipe is driven to rotate by the first driving module, and the partition cover is also driven to rotate, so that the high-temperature broken cadmium liquid can enter the multiple cooling zones in turn. At the same time, the cooling liquid in the rotating pipe and the partition cover can be circulated and cooled by the circulating mechanism. In addition, the broken cadmium liquid is cooled and blown by the blowing mechanism of the cooling zone. Therefore, the cadmium liquid can be first broken by high-temperature gas, and then the broken cadmium liquid can be quickly cooled and solidified in zones, so that it has more time to form regular spherical shape under the action of surface tension. In addition, the atomized powder particles can be dispersed to reduce the agglomeration phenomenon between the particles, and the quality of the powder preparation can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structure of the present application;

[0032] Figure 2 It is a schematic diagram of the internal structure of the shell in the present application;

[0033] Figure 3Structure diagram of the deflector and the gas nozzle in the application;

[0034] Figure 4 Structure diagram of the rotating mechanism in the application;

[0035] Figure 5 Structure diagram of the rotating cooling mechanism in the application;

[0036] Figure 6 Structure diagram of the rotating cooling mechanism in the application from another perspective;

[0037] Figure 7 Structure diagram of the rotating filter cylinder in the application;

[0038] Figure 8 Structure diagram of the first driving assembly in the application;

[0039] Figure 9 Structure diagram of the collecting mechanism in the application;

[0040] Figure 10 Structure diagram of the driving mechanism in the application;

[0041] Figure 11 Structure diagram of the rotating pipe, the partition cover and the rectangular cover in the application.

[0042] In the figure: 101, the shell; 102, the partition; 103, the smelting chamber; 104, the atomization chamber; 105, the first air inlet pipe; 106, the air return pipe; 107, the discharge valve; 108, the tundish; 109, the deflector; 110, the gas nozzle; 201, the second air inlet pipe; 202, the first annular cover; 203, the rotating disc; 204, the semicircular plate; 301, the first through hole; 302, the second annular cover; 303, the second connecting pipe; 304, the heat exchange cover; 305, the temperature sensor; 306, the circulating pump; 501, the annular groove; 502, the rotating cover; 503, the conical surface; 504, the second through hole; 601, the driven bevel gear; 602, the rotating rod; 603, the driving bevel gear; 604, the driven pulley; 605, the double-groove pulley; 606, the belt; 701, the conical filter hopper; 702, the rotating filter cylinder; 801, the worm gear; 802, the worm; 803, the rotating shaft; 901, the scraper; 902, the vertical plate; 903, the spring telescopic rod; 904, the moving frame; 905, the rubber column; 1001, the connecting rod; 1002, the pushing block; 1003, the cam; 11, the electric heating ring; 1201, the rotating pipe; 1202, the partition cover; 1203, the rectangular cover; 1204, the gas supply pipe; 1205, the first connecting pipe; 1206, the jet pipe. DETAILED DESCRIPTION

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Please see Figures 1-11 This invention provides a process for preparing high-purity cadmium powder, comprising the following steps:

[0045] S1: Loading: Accurately weigh 2.5 kg of 6N cadmium raw material that has been purified by distillation. After cleaning it by purging impurities twice, load it into a clean quartz crucible. Place the quartz crucible into the Czochralski furnace and seal the furnace door. Install a high-temperature resistant sealing gasket at the furnace door seal to improve the initial sealing performance.

[0046] S2: Vacuum treatment: Vacuum the Czochralski furnace in stages. First, evacuate to 10 Pa and hold for 10 min, then continue to evacuate to 0.1 Pa and hold for 30 min to ensure that the air inside the furnace is fully discharged.

[0047] S3: Leak Detection: The sealing performance of the Czochralski furnace was tested using a helium mass spectrometer leak detector;

[0048] S4: Pressure adjustment: High-purity argon gas is introduced into the furnace in two stages. First, it is introduced to 0.1MPa and held for 5 minutes, and then the pressure is increased to 0.25MPa to ensure that the argon atmosphere in the furnace is uniform and stable.

[0049] S5: Material preparation: Use a stepped heating method. First, heat the material to 300℃ and hold for 15 minutes. Then, heat the material to above the melting point of cadmium (approximately 321℃) and hold until the material is completely melted to avoid local overheating that could lead to oxidation of the raw materials.

[0050] S6: Stabilization: The temperature is precisely controlled at 450℃ with a temperature control accuracy of ±2℃, and the holding time is extended to 60 minutes to ensure uniform composition and temperature of the cadmium liquid.

[0051] S7: Crystal pulling: Directional seed crystals are selected for Czochralski crystal pulling, and the crystal pulling rate is controlled at 5-8 mm / h to ensure stable bonding between the seed crystal and the melt interface.

[0052] S8: Shoulder formation: Control the growth of the crystal shoulder at a rate of 3-5 mm / h, and control the shoulder angle at 12°-15° to avoid stress cracks in the crystal.

[0053] S9: Constant diameter: Maintain a constant temperature of 450℃ and grow crystals at a constant diameter growth rate of 4-6mm / h. Monitor the crystal diameter in real time and control the deviation within ±0.5mm.

[0054] S10: Finishing: Gradually reduce the pulling speed to 1-2 mm / h to finish the crystal. After finishing, first cool it to 350℃ and then further cool it to obtain high-purity cadmium crystals.

[0055] S11: Shutdown: Turn off the heater and use segmented cooling. First, cool the furnace to 200°C, then introduce argon gas to assist in cooling to room temperature to prevent crystal defects caused by sudden cooling.

[0056] S12: Powdering: Take cadmium purified by Czochralski extraction, remove the surface oxide layer, and then put it into an air atomization powder maker to make high-purity cadmium powder.

[0057] The gas atomizing powder maker includes a main body; the main body includes a shell 101, a partition 102 connected to the shell 101, and a melting chamber 103 and an atomizing chamber 104 located between the shell 101 and the partition 102; the main body also includes an intermediate ladle 108 disposed in the melting chamber 103 and a guide nozzle 109 connecting the intermediate ladle 108 and the atomizing chamber 104; the main body also includes a gas nozzle 110 connected to the partition 102, a first air inlet pipe 105 connected to the gas nozzle 110, and a return air pipe 106 connected to the atomizing chamber 104, all of which are well known in this technical field and will not be described in detail here; the main body also includes an electric heating ring 11 connected to the side wall of the first air inlet pipe 105; the main body also includes a rotary cooling mechanism for partitioned cooling and solidification of the crushed cadmium liquid.

[0058] The rotary cooling mechanism includes a rotating tube 1201 rotating within the atomization chamber 104, multiple partition covers 1202 communicating with the rotating tube 1201, and multiple rectangular covers 1203 communicating with the partition covers 1202; a cooling zone is formed between two adjacent partition covers 1202; the rotary cooling mechanism also includes an air blowing mechanism disposed in each cooling zone for cooling the crushed cadmium liquid; the rotating tube 1201 and the partition covers 1202 are filled with coolant; the rotary cooling mechanism also includes a circulation mechanism for circulating the coolant in the rotating tube 1201 and a first drive module for driving the rotating tube 1201 to rotate. When preparing high-purity cadmium powder using a gas atomization powder maker, the inert gas entering through the first air inlet pipe 105 is first heated by an electric heating ring 11. Hot, high-temperature gas is ejected through gas nozzle 110 to first break up the cadmium liquid. Then, the first drive module drives the rotating tube 1201 to rotate, which in turn drives the partition cover 1202 to rotate. This allows the cadmium liquid, after being broken up at high temperature, to enter multiple cooling zones in sequence. At the same time, a circulation mechanism can be used to circulate and cool the coolant in the rotating tube 1201 and the partition cover 1202. Furthermore, the air blowing mechanism in the cooling zone cools the broken-up liquid with air. Thus, the cadmium liquid is first broken up by high-temperature gas, and then the broken-up cadmium liquid is rapidly cooled and solidified in sections, allowing it more time to form regular spherical shapes under the action of surface tension. In addition, it can disperse the atomized powder particles, reduce the agglomeration of particles, and improve the quality of powder production.

[0059] The blowing mechanism includes multiple air supply pipes 1204 connected to the rotating tube 1201, a first connecting pipe 1205 communicating with the air supply pipes 1204, and a jet pipe 1206 communicating with the first connecting pipe 1205. The air supply pipes 1204 are disposed through the end of the rotating tube 1201. The first connecting pipe 1205 is inserted into the rectangular cover 1203. The jet pipe 1206 is disposed through the rectangular cover 1203. The blowing mechanism also includes an air supply mechanism for supplying air to the air supply pipes 1204. During cooling, room temperature air is supplied into the air supply pipes 1204 through the air supply mechanism, and then enters the first connecting pipe 1205 and is blown out through the jet pipe 1206, thereby cooling the cadmium droplets to form high-purity cadmium powder.

[0060] The air supply mechanism includes a second air inlet pipe 201 connected to the housing 101, a first annular cover 202 communicating with the second air inlet pipe 201, and a rotating disk 203 rotating inside the first annular cover 202; the rotating disk 203 is fixedly sleeved on the side wall of the air supply pipe 1204; the air supply mechanism also includes a semi-circular plate 204 connected to the first annular cover 202; the semi-circular plate 204 can provide a movable seal for the air supply pipe 1204, supplying room temperature air through the second air inlet pipe 201, then entering the first annular cover 202, and then entering the first connecting pipe 1205 through the air supply pipe 1204 and being blown out through the jet pipe 1206, thereby enabling the treatment of cadmium. The droplets are cooled to form high-purity cadmium powder. With the rotation of the rotating tube 1201 and the partition cover 1202, zoned cooling can be achieved, which can disperse the atomized powder particles, reduce the agglomeration of particles, and improve the quality of powder production. Furthermore, when the rotating tube 1201 rotates, it can drive the rotating disk 203 to rotate inside the first annular cover 202 through the air supply pipe 1204. When the air supply pipe 1204 is in contact with the semi-circular plate 204, it can be sealed, so that the jet pipe 1206 below the rotating tube 1201 no longer blows air, which can improve utilization efficiency.

[0061] The circulation mechanism includes a heat exchange shroud 304 connected to the first intake pipe 105, two second annular shrouds 302 rotating on the side wall of the rotating pipe 1201, and a second connecting pipe 303 connecting the second annular shrouds 302 and the heat exchange shroud 304. The second annular shrouds 302 are connected to the rotating pipe 1201 through a first through hole 301. The circulation mechanism also includes a circulation pump 306 connected to the second connecting pipe 303 and a temperature sensor 305 connected to the first intake pipe 105. When the circulation pump 306 is started, the coolant in the rotating pipe 1201, the partition shroud 1202, and the rectangular shroud 1203 can be circulated, resulting in higher cooling efficiency. Furthermore, the coolant after absorbing heat can enter the second annular shroud through the first through hole 301 on one side. The coolant enters the heat exchange hood 304 through the second connecting pipe 303 and exchanges heat with the first air inlet pipe 105. At this time, the inert gas in the first air inlet pipe 105 can be preheated. The temperature of the preheated gas is detected by the temperature sensor 305, and the power of the electric heating ring 11 is adjusted. The coolant that has been heated by the heat exchange hood 304 can be further cooled by the heat exchanger. Then, it returns to the rotating pipe 1201, the partition hood 1202 and the rectangular hood 1203 through the second connecting pipe 303, the second annular hood 302 and the first through hole 301 on the other side, which facilitates the circulation of the coolant, improves the cooling efficiency, and facilitates the recovery and reuse of waste heat, making it more energy-saving and environmentally friendly.

[0062] The main body of the device also includes a rotating mechanism for driving the gas nozzle 110 to rotate; the rotating mechanism includes an annular groove 501 opened at the bottom of the partition 102, a rotating cover 502 rotatably connected to the annular groove 501, and a first driving component for driving the rotating cover 502 to rotate; the rotating cover 502 communicates with the annular groove 501 through a second through hole 504; the annular groove 501 communicates with the first air inlet pipe 105; the rotating cover 502 includes a conical surface 503; the gas nozzle 110 is connected to the conical surface 503 and communicates with the interior of the rotating cover 502. When inert gas is blown through the gas nozzle 110, the rotating cover 502 can be driven to rotate by the first driving component. At the same time, the rotation of the gas nozzle 110 makes the blowing more uniform, making the crushing of cadmium liquid more uniform, and improving the quality of powder production.

[0063] The first drive assembly includes a driven bevel gear 601 connected to the rotating cover 502, a driving bevel gear 603 meshing with the driven bevel gear 601, and a rotating rod 602 connected between the driving bevel gear 603 and the partition plate 102. The first drive assembly also includes a driven pulley 604 connected to the rotating rod 602, a double-grooved pulley 605 connected to the rotating tube 1201, and a belt 606 connecting the driven pulley 604 and the double-grooved pulley 605. The first drive module drives the double-grooved pulley 605 to rotate, thereby causing the rotation... The tube 1201 and the partition cover 1202 rotate. When the double groove pulley 605 rotates, it can drive the driven pulley 604 and the rotating rod 602 to rotate through the belt 606. In turn, it drives the rotating cover 502 and the gas nozzle 110 to rotate through the driving bevel gear 603 and the driven bevel gear 601. The rotation of the rotating tube 1201 can be used as power to realize the rotation of the rotating cover 502 and the gas nozzle 110 without the need for additional power components. The first drive module is a well-known technology in this field and will not be described in detail here.

[0064] The main body of the device also includes a collection mechanism for collecting high-purity cadmium powder; the collection mechanism includes a rotating filter cylinder 702 rotating at the bottom of the atomization chamber 104 and a second drive assembly for driving the rotating filter cylinder 702 to rotate; the rotating filter cylinder 702 includes a conical filter hopper 701 and a discharge valve 107 connected to the bottom of the conical filter hopper 701; the discharge valve 107 is connected to the bottom of the housing 101, and the cooled high-purity cadmium powder can fall onto the conical filter hopper 701 and into the rotating filter cylinder 702 for collection. The collected high-purity cadmium powder can be discharged through the discharge valve 107, while the gas is discharged through the filter holes and then through the return gas pipe 106, which can prevent the high-purity cadmium powder from being discharged with the gas and improve the collection effect.

[0065] The second drive assembly includes a worm gear connected to the rotating filter cylinder, a worm meshing with the worm gear, and a rotating shaft connecting the worm and the housing. The second drive assembly also includes a second drive module for driving the rotating shaft to rotate. The second drive module drives the rotating shaft 803 to rotate, which in turn drives the worm 802 to rotate. This, in turn, drives the rotating filter cylinder 702 and the conical filter bucket 701 to rotate via the worm gear 801, thus preventing the accumulation of high-purity cadmium powder. The second drive module is a well-known technology in this field and will not be described in detail here.

[0066] The collection mechanism also includes a cleaning mechanism for cleaning the rotating filter cylinder 702; the cleaning mechanism includes a scraper 901 connected to the inner wall of the housing 101; the scraper 901 includes a vertical plate 902; the cleaning mechanism also includes a movable frame 904, a rubber column 905 connected to the movable frame 904, and a moving component that drives the movable frame 904 to reciprocate. When the rotating filter cylinder 702 and the conical filter bucket 701 rotate, the scraper 901 and the vertical plate 902 can scrape along the inner wall of the conical filter bucket 701 and the rotating filter cylinder 702, which can remove the adhering high-purity cadmium powder. At the same time, the moving component drives the movable frame 904 and the rubber column 905 to reciprocate, so that the rubber column 905 can reciprocate and vibrate the surface of the conical filter bucket 701 and the rotating filter cylinder 702, avoiding clogging of the filter holes.

[0067] The moving assembly includes a push block 1002, a connecting rod 1001 connecting the push block 1002 and the moving frame 904, and a spring telescopic rod 903 connecting the moving frame 904 and the housing 101. The moving assembly also includes a cam 1003 connected to a rotating shaft 803, allowing the push block 1002 to slide against the side wall of the cam 1003. When the rotating shaft 803 rotates, it can drive the cam 1003 to rotate synchronously. When the tip of the cam 1003 abuts against the side wall of the push block 1002, it can push... The push block 1002 moves, and at the same time, the connecting rod 1001 drives the moving frame 904 to move. The spring telescopic rod 903 is stretched. When the tip of the cam 1003 passes the side wall of the push block 1002, the moving frame 904 can move and reset under the action of the spring telescopic rod 903. By repeating this process, the moving frame 904 can move back and forth. The reciprocating movement of the moving frame 904 and the rubber column 905 can be realized by the rotation of the rotating shaft 803, which is more convenient to use and does not require an additional motor.

[0068] Working principle: When high-purity cadmium powder needs to be prepared, the cadmium purified by Czochralski extraction is put into the melting furnace in the melting chamber 103 for heating and melting, and then poured into the intermediate ladle 108. Then, it flows steadily into the atomization chamber 104 of the atomization zone through the guide nozzle 109.

[0069] Simultaneously, inert gas is introduced into the annular groove 501 through the first air inlet pipe 105, and heated by the electric heating ring 11. Then, the high-temperature inert gas enters the rotating shroud 502 through the second through-hole 504 and forms a high-speed airflow through the gas nozzle 110, impacting the flowing cadmium liquid. This overcomes the surface tension and viscosity of the cadmium liquid, breaking it into fine, uniform spherical droplets. The higher kinetic energy of the high-temperature gas allows for more efficient breaking of the cadmium liquid into finer droplets upon impact. Furthermore, the high temperature reduces the viscosity of the cadmium liquid, making it easier to disperse under the airflow, resulting in finer and more uniformly distributed powder particles. Additionally, the high-temperature environment prolongs the solidification time of the cadmium droplets, making... It allows more time for the droplets to form regular spheres under surface tension, avoiding the technical problem of irregular powder morphology caused by rapid cooling of room temperature gas and the droplets solidifying before full spheroidization. This improves the quality of powder production. The temperature difference between the droplets after high-temperature air breakup and the subsequent cooling medium is greater, resulting in a higher heat exchange rate. This allows cadmium droplets to solidify rapidly, effectively refining the grain structure and improving the physical properties of the powder. Furthermore, high-temperature inert gas is only used in the breakup stage, reducing the overall consumption of inert gases (such as argon) and lowering process costs. Subsequent room temperature air cooling can suppress cadmium oxidation through rapid cooling, keeping the oxidation risk within an acceptable range. If room temperature inert gas is used throughout the process, the cost will increase significantly.

[0070] The broken cadmium droplets can be cooled by a rotary cooling mechanism. During cooling, the first drive module drives the double-groove pulley 605 and the rotating tube 1201 to rotate, which in turn drives the partition cover 1202 to rotate. At the same time, room temperature air is supplied through the second air inlet pipe 201, then enters the first annular cover 202, enters the first connecting pipe 1205 through the air supply pipe 1204, and is blown out through the jet pipe 1206. This can cool the cadmium droplets to form high-purity cadmium powder. With the rotation of the rotating tube 1201 and the partition cover 1202, zoned cooling can be achieved, which can disperse the atomized powder particles, reduce the agglomeration of particles, and improve the quality of powder production.

[0071] Furthermore, by filling the rotating pipe 1201, the partition cover 1202, and the rectangular cover 1203 with coolant, the rectangular cover 1203 can increase the heat exchange area, improve the cooling efficiency and effect, and at the same time, it can also pre-cool the air ejected from the jet pipe 1206, further improving the cooling effect.

[0072] Meanwhile, the circulation pump 306 is started to circulate the coolant in the rotating pipe 1201, the partition cover 1202, and the rectangular cover 1203, making the cooling efficiency higher. The coolant after absorbing heat can enter the second annular cover 302 through the first through hole 301 on one side, and enter the heat exchange cover 304 through the second connecting pipe 303 to exchange heat with the first air inlet pipe 105. At this time, the inert gas in the first air inlet pipe 105 can be preheated. The temperature of the preheated gas is detected by the temperature sensor 305, and the power of the electric heating ring 11 is adjusted. The coolant that has exchanged heat through the heat exchange cover 304 can be further cooled by the heat exchanger. Then, it returns to the rotating pipe 1201, the partition cover 1202, and the rectangular cover 1203 through the second connecting pipe 303, the second annular cover 302, and the first through hole 301 on the other side, which facilitates the circulation of coolant, improves the cooling efficiency, and facilitates the recovery and reuse of waste heat, making it more energy-saving and environmentally friendly.

[0073] When the double-groove pulley 605 rotates, the belt 606 drives the driven pulley 604 and the rotating rod 602 to rotate, which in turn drives the rotating cover 502 and the gas nozzle 110 to rotate through the driving bevel gear 603 and the driven bevel gear 601, making the crushing of cadmium liquid more uniform and improving the quality of powder production.

[0074] The cooled high-purity cadmium powder falls onto the conical filter hopper 701 and into the rotating filter cylinder 702 for collection. The collected high-purity cadmium powder can be discharged through the discharge valve 107. At the same time, the second drive module is activated, which drives the worm gear 802 to rotate through the rotating shaft 803. This, in turn, drives the rotating filter cylinder 702 and the conical filter hopper 701 to rotate through the worm wheel 801. The gas passes through the filter holes and is discharged through the return gas pipe 106, which can prevent the high-purity cadmium powder from being discharged with the gas and improve the collection effect.

[0075] Furthermore, when the rotating tube 1201 rotates, it can drive the rotating disk 203 to rotate inside the first annular cover 202 through the air supply pipe 1204. When the air supply pipe 1204 is in contact with the semi-circular plate 204, it can block and seal the air supply pipe 1204, so that the jet pipe 1206 below the rotating tube 1201 no longer blows air, which can improve the utilization efficiency. At the same time, it avoids blowing up the cadmium powder on the conical filter bucket 701.

[0076] Meanwhile, scraper 901 and vertical plate 902 can scrape along the inner wall of conical filter bucket 701 and rotating filter cylinder 702, removing the adhering high-purity cadmium powder and preventing filter pore blockage. When the rotating shaft 803 rotates, it drives cam 1003 to rotate synchronously. When the tip of cam 1003 abuts against the side wall of push block 1002, it can push push block 1002 to move. At the same time, the moving frame 904 is moved by connecting rod 1001, and spring telescopic rod 903 is stretched. When the tip of cam 1003 passes the side wall of push block 1002, the moving frame 904 can move and reset under the action of spring telescopic rod 903. This reciprocating motion allows the moving frame 904 to move back and forth, driving rubber column 905 to move back and forth, which can reciprocate the surface of conical filter bucket 701 and rotating filter cylinder 702, preventing filter pore blockage.

Claims

1. A process for preparing high-purity cadmium powder, characterized in that: Includes the following steps: S1: Loading: After the 6N cadmium raw material that has been purified by distillation is cleaned by a second impurity purging, it is loaded into a clean quartz crucible. The quartz crucible is placed in the Czochralski furnace and the furnace door is sealed. A high-temperature resistant sealing gasket is installed at the furnace door seal to improve the initial sealing performance. S2: Vacuum treatment: Vacuum the Czochralski furnace in stages. First, evacuate to 10 Pa and hold for 10 min, then continue to evacuate to 0.1 Pa and hold for 30 min to ensure that the air inside the furnace is fully discharged. S3: Leak Detection: The sealing performance of the Czochralski furnace was tested using a helium mass spectrometer leak detector; S4: Pressure adjustment: High-purity argon gas is introduced into the furnace in two stages. First, it is introduced to 0.1MPa and held for 5 minutes, and then the pressure is increased to 0.25MPa to ensure that the argon atmosphere in the furnace is uniform and stable. S5: Chemical processing: adopt a stepped heating method, first heat up to 300℃ and hold for 15 minutes, then heat up to above the melting point of cadmium and hold until the material is completely melted, to avoid local overheating and oxidation of raw materials; S6: Stabilization: The temperature is precisely controlled at 450℃ with a temperature control accuracy of ±2℃, and the holding time is extended to 60 minutes to ensure uniform composition and temperature of the cadmium liquid. S7: Crystal pulling: Directional seed crystals are selected for Czochralski crystal pulling, and the crystal pulling rate is controlled at 5-8 mm / h to ensure stable bonding between the seed crystal and the melt interface. S8: Shoulder formation: Control the growth of the crystal shoulder at a rate of 3-5 mm / h, and control the shoulder angle at 12°-15° to avoid stress cracks in the crystal. S9: Constant diameter: Maintain a constant temperature of 450℃ and grow crystals at a constant diameter growth rate of 4-6mm / h. Monitor the crystal diameter in real time and control the deviation within ±0.5mm. S10: Finishing: Gradually reduce the pulling speed to 1-2 mm / h to finish the crystal. After finishing, first cool it to 350℃ and then further cool it to obtain high-purity cadmium crystals. S11: Shutdown: Turn off the heater and use segmented cooling. First, cool the furnace to 200°C, then introduce argon gas to assist in cooling to room temperature to prevent crystal defects caused by sudden cooling. S12: Powdering: Take cadmium purified by Czochralski extraction, remove the surface oxide layer, and then put it into an air atomization powder maker to make high-purity cadmium powder. The atomizing powder generator includes a main body; the main body includes a shell (101), a partition (102), a guide nozzle (109), a gas nozzle (110), and a first air inlet pipe (105); the main body also includes an electric heating ring (11) connected to the side wall of the first air inlet pipe (105); the main body also includes a rotary cooling mechanism for partitioning and solidifying the crushed cadmium liquid into cadmium powder. The rotary cooling mechanism includes a rotary tube (1201) rotating within an atomization chamber (104), a plurality of partition covers (1202) communicating with the rotary tube (1201), and a plurality of rectangular covers (1203) communicating with the partition covers (1202); a cooling zone is formed between two adjacent partition covers (1202); the rotary cooling mechanism also includes an air blowing mechanism disposed in each cooling zone for cooling the broken cadmium liquid by blowing air; the rotary tube (1201) and the partition covers (1202) are filled with coolant; the rotary cooling mechanism also includes a circulation mechanism for circulating the coolant in the rotary tube (1201) and a first drive module for driving the rotary tube (1201) to rotate.

2. The high-purity cadmium powder preparation process according to claim 1, characterized in that: The blowing mechanism includes a plurality of air supply pipes (1204) connected in the rotating tube (1201), a first connecting pipe (1205) communicating with the air supply pipes (1204), and a jet pipe (1206) communicating with the first connecting pipe (1205); the air supply pipes (1204) are disposed through the end of the rotating tube (1201); the first connecting pipe (1205) is inserted in the rectangular cover (1203); the jet pipe (1206) is disposed through the rectangular cover (1203); the blowing mechanism also includes an air supply mechanism for supplying air into the air supply pipes (1204).

3. The high-purity cadmium powder preparation process according to claim 2, characterized in that: The air supply mechanism includes a second air inlet pipe (201) connected to the housing (101), a first annular cover (202) communicating with the second air inlet pipe (201), and a rotating disk (203) rotating inside the first annular cover (202); the rotating disk (203) is fixedly sleeved on the side wall of the air supply pipe (1204); the air supply mechanism also includes a semi-circular plate (204) connected to the first annular cover (202); the semi-circular plate (204) can provide a movable seal for the air supply pipe (1204).

4. The process for preparing high-purity cadmium powder according to claim 1, characterized in that: The circulation mechanism includes a heat exchange shroud (304) connected to the first air inlet pipe (105), two second annular shrouds (302) rotating on the side wall of the rotating pipe (1201), and a second connecting pipe (303) connecting the second annular shrouds (302) and the heat exchange shrouds (304); the second annular shrouds (302) are connected to the rotating pipe (1201) through a first through hole (301); the circulation mechanism also includes a circulation pump (306) connected to the second connecting pipe (303) and a temperature sensor (305) connected to the first air inlet pipe (105).

5. The process for preparing high-purity cadmium powder according to claim 1, characterized in that: The main body of the device also includes a rotating mechanism for driving the gas nozzle (110) to rotate; the rotating mechanism includes an annular groove (501) opened at the bottom of the partition (102), a rotating cover (502) rotatably connected to the annular groove (501), and a first driving component for driving the rotating cover (502) to rotate; the rotating cover (502) is connected to the annular groove (501) through a second through hole (504); the annular groove (501) is connected to the first air inlet pipe (105); the rotating cover (502) includes a conical surface (503); the gas nozzle (110) is connected to the conical surface (503) and communicates with the interior of the rotating cover (502).

6. The process for preparing high-purity cadmium powder according to claim 5, characterized in that: The first drive assembly includes a driven bevel gear (601) connected to the rotating cover (502), a driving bevel gear (603) meshing with the driven bevel gear (601), and a rotating rod (602) connected between the driving bevel gear (603) and the partition (102); the first drive assembly also includes a driven pulley (604) connected to the rotating rod (602), a double groove pulley (605) connected to the rotating tube (1201), and a belt (606) connected between the driven pulley (604) and the double groove pulley (605).

7. The process for preparing high-purity cadmium powder according to claim 1, characterized in that: The main body of the device also includes a collection mechanism for collecting high-purity cadmium powder; the collection mechanism includes a rotating filter cylinder (702) rotating at the bottom of the atomization chamber (104) and a second drive assembly for driving the rotating filter cylinder (702) to rotate; the rotating filter cylinder (702) includes a conical filter bucket (701) and a discharge valve (107) connected to the bottom of the conical filter bucket (701); the discharge valve (107) is connected to the bottom of the housing (101).

8. The process for preparing high-purity cadmium powder according to claim 7, characterized in that: The second drive assembly includes a worm gear (801) connected to the rotating filter cylinder (702), a worm (802) meshing with the worm gear (801), and a rotating shaft (803) connected between the worm (802) and the housing (101); the second drive assembly also includes a second drive module for driving the rotating shaft (803) to rotate.

9. The process for preparing high-purity cadmium powder according to claim 7, characterized in that: The collection mechanism also includes a cleaning mechanism for cleaning the rotating filter cylinder (702); the cleaning mechanism includes a scraper (901) connected to the inner wall of the housing (101); the scraper (901) includes a vertical plate (902); the cleaning mechanism also includes a movable frame (904), a rubber column (905) connected to the movable frame (904), and a moving component for driving the movable frame (904) to reciprocate.

10. The process for preparing high-purity cadmium powder according to claim 9, characterized in that: The moving assembly includes a push block (1002), a connecting rod (1001) connecting the push block (1002) and the moving frame (904), and a spring telescopic rod (903) connecting the moving frame (904) and the housing (101); the moving assembly also includes a cam (1003) connected to the rotating shaft (803) so that the push block (1002) can slide on the side wall of the cam (1003).

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