Preparation process of high-purity cadmium powder

Abstract

The invention discloses a preparation process of high-purity cadmium powder, and relates to the technical field of metal powder manufacturing. The preparation process of the high-purity cadmium powder comprises the following steps: S1, charging: carrying out secondary impurity purging and cleaning on a 6N cadmium raw material subjected to distillation purification, then putting the 6N cadmium raw material into a clean quartz crucible, putting the quartz crucible into a straight pulling furnace, sealing a furnace door, and additionally arranging a high-temperature-resistant sealing gasket at the sealing part of the furnace door, so as to improve the initial sealing property; according to the preparation technology of the high-purity cadmium powder, when the gas atomization powder making machine is used for preparing the high-purity cadmium powder, firstly, high-temperature gas is used for crushing cadmium liquid, then, a first driving module drives a rotating pipe to rotate, and a separation cover is driven to rotate; according to the cooling device, the multiple cooling areas are arranged, so that the cadmium liquid subjected to high-temperature crushing can sequentially enter the multiple cooling areas to be rapidly cooled and solidified in different areas, more sufficient time is provided for the cadmium liquid to form regular spheres under the action of surface tension, the atomized powder particles can be dispersed, the agglomeration phenomenon among 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 materials (for example, high-purity cadmium crystals obtained by the Czochralski method) are 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 break and cool 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, resulting in irregular powder morphology and affecting the quality of the powder making. In addition, the cadmium powder particles after cooling are prone to agglomeration, which also affects the quality of the 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 purpose, the present application provides the following technical scheme: a high-purity cadmium powder preparation process, comprising the following steps: S1: charging: accurately weighing 2.5 Kg of 6N cadmium raw material purified by distillation, and charging the cleaned cadmium raw material into a clean quartz crucible after impurity secondary purging. 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. S2: vacuum treatment: the Czochralski furnace is subjected to staged vacuumizing. First, vacuumizing to 10 Pa for 10 min, and then continuing to vacuumize to 0.1 Pa for 30 min to ensure that the air in the furnace is fully discharged. S3: leak detection: using a helium mass spectrometric leak detector to detect the sealing performance of the Czochralski furnace. S4: pressure regulation: fill high-purity argon into the furnace twice, first to 0.1 MPa for 5 min, then to 0.25 MPa, to ensure uniform and stable argon atmosphere in the furnace; S5: material melting: use stepwise temperature rise, first to 300℃ for 15 min, then to above the melting point of cadmium (about 321℃) and keep the temperature until the material is completely melted, to avoid local overheating leading to oxidation of raw materials; S6: stabilization: precisely control the temperature at 450℃, with a temperature control accuracy of ±2℃, and extend the holding time to 60 min to ensure uniform composition and temperature of the cadmium liquid; S7: seeding: use directional seeding for direct seeding, with a seeding rate controlled at 5-8 mm / h to ensure stable combination of the seed and the melt interface; S8: shoulder: control the crystal shoulder growth rate at 3-5 mm / h, and the shoulder angle at 12°-15° to avoid stress cracks in the crystal; S9: equal diameter: maintain 450℃ constant temperature, and grow the crystal at an equal diameter growth rate of 4-6 mm / h, real-time monitor the crystal diameter, and control the deviation within ±0.5 mm; S10: end: gradually reduce the pulling rate to 1-2 mm / h for end processing of the crystal, and then cool down to 350℃ before further cooling to obtain high-purity cadmium crystal; S11: furnace shutdown: turn off the heater, and use stepwise cooling, first cool down to 200℃ with the furnace, then cool down to room temperature with argon to prevent defects in the crystal due to sudden cooling; S12: powder making: take the direct-lift purified cadmium, remove the surface oxidation layer, and then put it into a gas atomization powder making machine to make high-purity cadmium powder; The gas atomization powder making machine comprises a device main body; the device main body comprises a shell, a partition connected with the shell, and a smelting chamber and an atomization chamber between the shell and the partition; 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, 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; 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] Preferably, the first driving assembly comprises a driven bevel gear connected with the rotating cover, a driving bevel gear meshed 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.

[0011] 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 atomization 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] Compared with the prior art, the present application has the following advantages: The high-purity cadmium powder preparation process sets a rotating cooling mechanism, etc. When using a gas atomization powder 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 can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the present application;

[0017] Figure 2 It is a schematic diagram of the internal structure of the shell in the present application;

[0018] Figure 3Structure diagram of the deflector and the gas nozzle in the application;

[0019] Figure 4 Structure diagram of the rotating mechanism in the application;

[0020] Figure 5 Structure diagram of the rotating cooling mechanism in the application;

[0021] Figure 6 Structure diagram of the rotating cooling mechanism in the application from another perspective;

[0022] Figure 7 Structure diagram of the rotating filter cylinder in the application;

[0023] Figure 8 Structure diagram of the first driving assembly in the application;

[0024] Figure 9 Structure diagram of the collecting mechanism in the application;

[0025] Figure 10 Structure diagram of the driving mechanism in the application;

[0026] Figure 11 Structure diagram of the rotating pipe, the partition cover and the rectangular cover in the application.

[0027] 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

[0028] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0029] Please refer to Figures 1-11 The present application provides a high-purity cadmium powder preparation process, comprising the following steps: S1: charging: accurately weighing 2.5 Kg of 6N cadmium raw material purified by distillation, and charging into a clean quartz crucible after cleaning by impurity secondary purging, and placing the quartz crucible into a vertical pulling furnace and sealing the furnace door, and adding a high-temperature-resistant sealing gasket at the sealing part of the furnace door to improve the initial sealing performance; S2: vacuum treatment: the vertical pulling furnace is subjected to staged vacuumizing, first vacuumizing to 10 Pa and maintaining for 10 min, and then continuing to vacuumize to 0.1 Pa and maintaining for 30 min to ensure that the air in the furnace is fully discharged; S3: leak detection: using a helium mass spectrometry leak detector to detect the sealing performance of the vertical pulling furnace; S4: pressure regulation: filling high-purity argon into the furnace in two times, first filling to 0.1 MPa and maintaining for 5 min, and then supplementing the pressure to 0.25 MPa to ensure that the argon atmosphere in the furnace is uniform and stable; S5: material melting: using stepwise temperature rising, first rising to 300 ℃ and maintaining for 15 min, and then rising to above the melting point of cadmium (about 321 ℃) and maintaining until the material is completely melted to avoid local overheating leading to oxidation of the raw material; S6: stabilization: precisely and constantly controlling the temperature at 450 ℃, the temperature control accuracy is ± 2 ℃, and the holding time is extended to 60 min to ensure that the cadmium liquid composition and temperature are uniform; S7: crystal pulling: using a directional seed crystal for vertical pulling, and controlling the pulling rate at 5-8 mm / h to ensure stable combination of the crystal seed and the melt interface; S8: shoulder growth: controlling the crystal shoulder growth rate at 3-5 mm / h, and controlling the shoulder angle at 12°-15° to avoid stress cracks of the crystal; S9: equal diameter growth: maintaining the constant temperature at 450 ℃, and performing crystal growth at an equal diameter growth rate of 4-6 mm / h, and real-time monitoring the crystal diameter, and controlling the deviation within ± 0.5 mm; S10: finishing: gradually reducing the pulling rate to 1-2 mm / h for finishing treatment of the crystal, and then reducing the temperature to 350 ℃ before further cooling to obtain the high-purity cadmium crystal; S11: furnace shutdown: turning off the heater, and using stepwise cooling, first cooling to 200 ℃ with the furnace, and then cooling to room temperature by introducing argon to prevent defects of the crystal caused by sudden cooling; S12: milling: taking straightly drawn and purified cadmium, after surface oxide layer removal treatment, putting into a gas atomization powder making machine to make high purity cadmium powder; The gas atomization powder making machine comprises a device main body; the device main body comprises a shell 101, a partition plate 102 connected with the shell 101, a smelting chamber 103 and an atomization chamber 104 between the shell 101 and the partition plate 102; the device main body further comprises a tundish 108 arranged in the smelting chamber 103 and a flow guide nozzle 109 communicating the tundish 108 and the atomization chamber 104; the device main body further comprises a gas nozzle 110 connected with the partition plate 102, a first gas inlet pipe 105 communicating the gas nozzle 110 and a gas return pipe 106 communicating the atomization chamber 104, which are all known technologies in the technical field and will not be described here; the device main body further comprises an electric heating ring 11 connected to the side wall of the first gas inlet pipe 105; the device main body further comprises a rotary cooling mechanism for partition cooling and solidification of the broken cadmium liquid; The rotary cooling mechanism comprises a rotary pipe 1201 rotating in the atomization chamber 104, a plurality of partition covers 1202 communicating with the rotary pipe 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 further comprises a blowing mechanism arranged in each cooling zone for blowing and cooling the broken cadmium liquid; the rotary pipe 1201 and the partition cover 1202 are filled with cooling liquid; the rotary cooling mechanism further comprises a circulating mechanism for circulating the cooling liquid in the rotary pipe 1201 and a first driving module for driving the rotary pipe 1201 to rotate; when preparing high purity cadmium powder by using the gas atomization powder making machine, the inert gas entering the first gas inlet pipe 105 is heated by using the electric heating ring 11, the high temperature gas is sprayed out through the gas nozzle 110 to break the cadmium liquid first, then the rotary pipe 1201 is driven to rotate by the first driving module, and the partition cover 1202 is driven to rotate, so that the high temperature broken cadmium liquid can enter the plurality of cooling zones in turn, at the same time, the cooling liquid in the rotary pipe 1201 and the partition cover 1202 can be circulated and cooled by the circulating mechanism, and the broken cadmium liquid is blown and cooled by the blowing mechanism of the cooling zone, so that the cadmium liquid can be broken by using high temperature gas first, then the broken cadmium liquid can be partitioned and rapidly cooled and solidified, so that it has more sufficient time to form regular spherical shape under the action of surface tension, and the atomized powder particles can be dispersed, the agglomeration phenomenon between the particles can be reduced, and the quality of powder making can be improved.

[0030] The blowing mechanism comprises a plurality of air supply pipes 1204 connected in the rotating pipe 1201, a first connecting pipe 1205 communicated with the air supply pipes 1204, and a jet pipe 1206 communicated with the first connecting pipe 1205; the air supply pipes 1204 are arranged through the end of the rotating pipe 1201; the first connecting pipe 1205 is inserted in the rectangular cover 1203; the jet pipe 1206 is arranged through the rectangular cover 1203; the blowing mechanism further comprises an air supply mechanism for supplying air into the air supply pipes 1204; when cooling, the air supply mechanism supplies normal temperature air into the air supply pipes 1204, then into the first connecting pipe 1205 and is blown out through the jet pipe 1206, so that the cadmium liquid drops can be cooled to form high-purity cadmium powder.

[0031] The air supply mechanism comprises a second air inlet pipe 201 connected with the shell 101, a first annular cover 202 communicated with the second air inlet pipe 201, and a rotating disc 203 rotating in the first annular cover 202; the rotating disc 203 is fixedly sleeved on the side wall of the air supply pipe 1204; the air supply mechanism further comprises a semicircular plate 204 connected with the first annular cover 202; the semicircular plate 204 can movably seal the air supply pipe 1204; the second air inlet pipe 201 supplies normal temperature air, then the air enters the first annular cover 202, and then enters the first connecting pipe 1205 through the air supply pipe 1204 and is blown out through the jet pipe 1206, so that the cadmium liquid drops can be cooled to form high-purity cadmium powder; with the rotation of the rotating pipe 1201 and the partition cover 1202, the partition cooling can be realized, the dispersed effect on the atomized powder particles can be achieved, the agglomeration phenomenon between the particles can be reduced, the powder quality can be improved, and when the rotating pipe 1201 rotates, the rotating disc 203 can be driven to rotate in the first annular cover 202 through the air supply pipe 1204; when the air supply pipe 1204 is attached to the semicircular plate 204, the air supply pipe 1204 can be sealed, so that the jet pipe 1206 below the rotating pipe 1201 no longer blows air, and the utilization efficiency can be improved.

[0032] The circulating mechanism comprises a heat exchange cover 304 connected with the first air inlet pipe 105, two second annular covers 302 rotating on the side wall of the rotating pipe 1201, and a second connecting pipe 303 communicated between the second annular cover 302 and the heat exchange cover 304; the second annular cover 302 is communicated with the rotating pipe 1201 through a first through hole 301; the circulating mechanism further comprises a circulating pump 306 connected with the second connecting pipe 303 and a temperature sensor 305 connected on the first air inlet pipe 105; when the circulating pump 306 is started, the cooling liquid in the rotating pipe 1201, the partition cover 1202 and the rectangular cover 1203 can be circulated, so that the cooling efficiency is higher; the cooled cooling liquid 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, and heat exchange 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 cooling liquid exchanged by the heat exchange cover 304 can be further cooled by the heat exchanger; then, the cooling liquid returns to the rotating pipe 1201, the partition cover 1202 and the rectangular cover 1203 through the second connecting pipe 303 on the other side, the second annular cover 302 and the first through hole 301, so as to facilitate the circulation of the cooling liquid, improve the cooling efficiency, and facilitate the recycling of waste heat, which is more energy-saving and environment-friendly.

[0033] The device body further comprises a rotating mechanism for driving the gas nozzle 110 to rotate; the rotating mechanism comprises an annular groove 501 formed in the bottom of the partition plate 102, a rotating cover 502 rotationally connected with the annular groove 501, and a first driving assembly for driving the rotating cover 502 to rotate; the rotating cover 502 is communicated with the annular groove 501 through a second through hole 504; the annular groove 501 is communicated with the first air inlet pipe 105; the rotating cover 502 comprises a conical surface 503; the gas nozzle 110 is connected with the conical surface 503 and communicated with the inside of the rotating cover 502; when the inert gas is blown through the gas nozzle 110, the rotating cover 502 can be driven to rotate by the first driving assembly, and at the same time, the gas nozzle 110 rotates, so that the blowing is more uniform, the crushing of the cadmium liquid is more uniform, and the quality of the powder is improved.

[0034] The first driving assembly comprises a driven bevel gear 601 connected with the rotating cover 502, a driving bevel gear 603 engaged 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 driving assembly further comprises a driven pulley 604 connected with the rotating rod 602, a double-groove pulley 605 connected with the rotating tube 1201, and a belt 606 connected between the driven pulley 604 and the double-groove pulley 605; the double-groove pulley 605 is driven to rotate by the first driving module, and the rotating tube 1201 and the partition cover 1202 are driven to rotate; when the double-groove pulley 605 rotates, the driven pulley 604 and the rotating rod 602 are driven to rotate through the belt 606, and then the rotating cover 502 and the gas nozzle 110 are driven to rotate through the driving bevel gear 603 and the driven bevel gear 601; the rotation of the rotating tube 1201 is used as power to realize the rotation of the rotating cover 502 and the gas nozzle 110, and no additional power assembly is needed; the first driving module is a known technology in the technical field, and will not be described here.

[0035] The device body further comprises a collecting mechanism for collecting high-purity cadmium powder; the collecting mechanism comprises a rotating filter cylinder 702 rotating at the bottom of the atomization chamber 104 and a second driving assembly for driving the rotating filter cylinder 702 to rotate; the rotating filter cylinder 702 comprises a conical filter hopper 701 and a discharge valve 107 communicated with the bottom of the conical filter hopper 701; the discharge valve 107 is connected with the bottom of the shell 101, and the cooled high-purity cadmium powder can fall on the conical filter hopper 701 and fall into the rotating filter cylinder 702 for collection; the collected high-purity cadmium powder can be discharged through the discharge valve 107, and the gas is discharged through the gas return pipe 106 after passing through the filter hole, which can avoid the high-purity cadmium powder from being discharged with the gas and improve the collection effect.

[0036] The second driving assembly comprises a worm gear connected with the rotating filter cylinder, a worm connected with 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; the rotating shaft 803 is driven to rotate by the second driving module, and the worm 802 is driven to rotate, so that the rotating filter cylinder 702 and the conical filter hopper 701 are driven to rotate through the worm gear 801, which can avoid the accumulation of high-purity cadmium powder; the second driving module is a known technology in the technical field, and will not be described here.

[0037] The collecting mechanism further comprises a cleaning mechanism for cleaning the rotary filter cylinder 702; the cleaning mechanism comprises a scraper 901 connected with the inner wall of the shell 101; the scraper 901 comprises a vertical plate 902; the cleaning mechanism further comprises a moving frame 904, a rubber column 905 connected with the moving frame 904 and a moving assembly for driving the moving frame 904 to move back and forth; when the rotary filter cylinder 702 and the conical filter hopper 701 rotate, the scraper 901 and the vertical plate 902 can scrape along the inner wall of the conical filter hopper 701 and the rotary filter cylinder 702, so as to scrape off the adhered high-purity cadmium powder; at the same time, the moving assembly drives the moving frame 904 and the rubber column 905 to move back and forth, so that the rubber column 905 can vibrate the surface of the conical filter hopper 701 and the rotary filter cylinder 702 back and forth, thereby avoiding the blockage of filter holes.

[0038] The moving assembly comprises a pushing block 1002, a connecting rod 1001 connected between the pushing block 1002 and the moving frame 904 and a spring telescopic rod 903 connected between the moving frame 904 and the shell 101; the moving assembly further comprises a cam 1003 connected with the rotating shaft 803, so that the pushing block 1002 can slide along the side wall of the cam 1003; when the rotating shaft 803 rotates, the cam 1003 can be driven to rotate synchronously; when the tip of the cam 1003 abuts against the side wall of the pushing block 1002, the pushing block 1002 can be pushed to move; at the same time, the connecting rod 1001 drives the moving frame 904 to move, and the spring telescopic rod 903 is stretched; when the tip of the cam 1003 passes the side wall of the pushing block 1002, the moving frame 904 can be moved back to the original position under the action of the spring telescopic rod 903; in this way, the moving frame 904 can move back and forth, and the rotating shaft 803 can be used to realize the back-and-forth movement of the moving frame 904 and the rubber column 905, so that the use is more convenient, and an additional motor is not needed.

[0039] Working principle: when high-purity cadmium powder is needed, the straight-pulling purified cadmium is put into the smelting furnace in the smelting chamber 103 to be heated and melted, and then poured into the tundish 108, and then stably flows into the atomization area atomization chamber 104 through the flow guide nozzle 109.

[0040] Meanwhile, inert gas is introduced into the annular groove 501 through the first gas inlet pipe 105, and at the same time, heating is carried out under the action of the electric heating ring 11, then the high-temperature inert gas can enter the rotating cover 502 through the second through hole 504 and form a high-speed gas flow through the gas nozzle 110 and impact on the flowing cadmium liquid, overcome the surface tension and viscosity of the cadmium liquid, and break it into fine and uniform spherical droplets. The kinetic energy of the high-temperature gas is higher, and when it impacts the cadmium liquid, it can more efficiently break it into smaller droplets. At the same time, the high temperature can reduce the viscosity of the cadmium liquid, making it easier to disperse under the action of the gas flow. The final powder has a finer particle size and a more uniform distribution. Moreover, the high-temperature environment prolongs the solidification time of the cadmium droplets, allowing them more time to form regular spheres under the action of surface tension. This avoids the technical problem of irregular powder morphology caused by the rapid cooling of normal temperature gas, which can easily cause the droplets to solidify before they are fully spherical. This can improve the quality of the powder. The temperature difference between the droplets broken by high-temperature air and the subsequent cooling medium is greater, and the heat exchange rate is higher, which can make the cadmium droplets solidify quickly, effectively refine the grain structure, and improve the physical properties of the powder. Moreover, high-temperature inert gas is only used in the breaking stage, which can reduce the overall consumption of inert gas (such as argon) and lower the process cost. Subsequent cooling by normal temperature air can inhibit the oxidation of cadmium by rapidly cooling it, keeping the oxidation risk within an acceptable range. If normal temperature inert gas is used throughout the process, the cost will increase significantly.

[0041] The broken cadmium droplets can be cooled under the action of the rotating cooling mechanism. During cooling, the first drive module drives the double-groove pulley 605 and the rotating pipe 1201 to rotate, and the partition cover 1202 is also rotated. At the same time, normal temperature air is supplied through the second gas inlet pipe 201, then enters the first annular cover 202, and then enters the first connecting pipe 1205 through the gas supply pipe 1204 and is blown out through the air jet pipe 1206, thereby cooling the cadmium droplets to form high-purity cadmium powder. With the rotation of the rotating pipe 1201 and the partition cover 1202, zoned cooling can be achieved, which can disperse the atomized powder particles and reduce the agglomeration between particles, thereby improving the quality of the powder.

[0042] Moreover, by filling the rotating pipe 1201, the partition cover 1202 and the rectangular cover 1203 with cooling liquid, the rectangular cover 1203 can increase the heat exchange area and improve the cooling efficiency and effect. At the same time, it can also cool the air blown out by the air jet pipe 1206 in advance, further improving the cooling effect.

[0043] Meanwhile, the circulating pump 306 is started, and the cooling liquid in the rotating tube 1201, the partition cover 1202 and the rectangular cover 1203 can be circulated, so that the cooling efficiency is higher, and the cooled cooling liquid 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, and 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 cooling liquid exchanged by the heat exchange cover 304 can be further cooled by the heat exchanger, and then returned to the rotating tube 1201, the partition cover 1202 and the rectangular cover 1203 through the second connecting pipe 303 on the other side, the second annular cover 302 and the first through hole 301, so as to circulate the cooling liquid, improve the cooling efficiency, and recycle the waste heat, which is more energy-saving and environment-friendly.

[0044] When the double-groove pulley 605 rotates, the driven pulley 604 and the rotating rod 602 are driven to rotate by the belt 606, and then the rotating cover 502 and the gas nozzle 110 are driven to rotate by the driving bevel gear 603 and the driven bevel gear 601, so that the crushing of the cadmium liquid is more uniform, and the quality of the powder is improved.

[0045] The high-purity cadmium powder after cooling can fall on the conical filter hopper 701 and fall into the rotating filter cylinder 702 for collection. The collected high-purity cadmium powder can be discharged through the discharge valve 107. Meanwhile, the second driving module is started, the rotating filter cylinder 702 and the conical filter hopper 701 are driven to rotate by the worm gear 802 through the worm wheel 801, and the gas is discharged through the gas return pipe 106 after passing through the filter hole, so that the high-purity cadmium powder can be prevented from being discharged with the gas, and the collection effect can be improved.

[0046] Moreover, when the rotating tube 1201 rotates, the rotating disc 203 can be driven to rotate in the first annular cover 202 by the gas supply pipe 1204. When the gas supply pipe 1204 is attached to the semicircular plate 204, the gas supply pipe 1204 can be sealed, so that the gas jet pipe 1206 below the rotating tube 1201 no longer blows gas, the utilization efficiency is improved, and the cadmium powder on the conical filter hopper 701 is prevented from being blown up.

[0047] Meanwhile, the scraper 901 and the vertical plate 902 can scrape along the inner wall of the conical filter hopper 701 and the rotating filter cylinder 702, and can scrape off the adhered high-purity cadmium powder, so as to avoid filter hole blockage. When the rotating shaft 803 rotates, the cam 1003 can be driven to rotate synchronously. When the tip of the cam 1003 abuts against the side wall of the push block 1002, the push block 1002 can be pushed to move. At the same time, the connecting rod 1001 drives the moving frame 904 to move, and 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 be moved to reset under the action of the spring telescopic rod 903. Thus, the moving frame 904 can be reciprocated, and the rubber column 905 can be reciprocated, so as to reciprocate the surface of the conical filter hopper 701 and the rotating filter cylinder 702, and avoid filter hole blockage.

Claims

1. A process for preparing high-purity cadmium powder, characterized in that: The method comprises the following steps: S1: charging: after the 6N cadmium raw material purified by distillation is cleaned by impurity secondary blowing, it is loaded into a clean quartz crucible, the quartz crucible is placed in a vertical pulling furnace and the furnace door is sealed, a high-temperature-resistant sealing gasket is installed at the sealing part of the furnace door to improve the initial sealing performance; S2: vacuum treatment: the vertical pulling furnace is subjected to staged vacuumization, first vacuumized to 10 Pa and kept for 10 min, then vacuumized to 0.1 Pa and kept for 30 min to ensure that the air in the furnace is fully discharged; S3: leak detection: the sealing performance of the vertical pulling furnace is detected by using a helium mass spectrometer leak detector; S4: pressure regulation: high-purity argon is filled into the furnace in two times, first filled to 0.1 MPa and kept for 5 min, then supplemented to 0.25 MPa to ensure that the argon atmosphere in the furnace is uniform and stable; S5: material melting: the temperature is increased in steps, first increased to 300 DEG C and kept for 15 min, then increased to above the melting point of cadmium and kept until the material is completely melted to avoid local overheating and oxidation of the raw material; S6: stabilization: the temperature is accurately and constantly controlled at 450 DEG C with a temperature control accuracy of ± 2 DEG C, and the holding time is extended to 60 min to ensure that the cadmium liquid composition and temperature are uniform; S7: crystal pulling: a directional seed crystal is selected for vertical pulling, and the pulling rate is controlled at 5-8 mm / h to ensure that the crystal seed and the melt interface are stably combined; S8: shoulder setting: the crystal is grown at a rate of 3-5 mm / h, and the shoulder angle is controlled at 12 DEG -15 DEG to avoid stress cracks in the crystal; S9: equal diameter: the crystal is grown at a constant diameter growth rate of 4-6 mm / h while maintaining a constant temperature of 450 DEG C, and the crystal diameter is monitored in real time with a deviation controlled within ± 0.5 mm; S10: finishing: the crystal is finished by gradually reducing the pulling rate to 1-2 mm / h, and then cooled to 350 DEG C before further cooling to obtain high-purity cadmium crystals; S11: furnace shutdown: the heater is turned off, and the temperature is lowered in stages, first cooled to 200 DEG C with the furnace, then cooled to room temperature by introducing argon to prevent defects in the crystal due to sudden cooling; S12: powder making: the vertical pulling purified cadmium is subjected to surface oxide layer removal treatment and then put into a gas atomization powder making machine to make high-purity cadmium powder; The gas atomization powder making machine comprises a device main body; the device main body comprises a shell (101), a partition plate (102), a flow guide nozzle (109), a gas nozzle (110) and a first air inlet pipe (105); the device main body further comprises an electric heating ring (11) connected to the side wall of the first air inlet pipe (105); the device main body further comprises a rotating cooling mechanism for cooling and solidifying the broken cadmium liquid into cadmium powder. The rotating cooling mechanism comprises a rotating pipe (1201) rotating in the atomizing chamber (104), a plurality of partition covers (1202) in communication with the rotating pipe (1201), and a plurality of rectangular covers (1203) in communication with the partition covers (1202); two adjacent partition covers (1202) form a cooling zone; the rotating cooling mechanism further comprises a blowing mechanism arranged in each cooling zone for blowing and cooling the broken cadmium liquid; the rotating pipe (1201) and the partition cover (1202) are filled with cooling liquid; the rotating cooling mechanism further comprises a circulating mechanism for circulating the cooling liquid in the rotating pipe (1201) and a first driving module for driving the rotating pipe (1201) to rotate.

2. The process for preparing high purity cadmium powder as claimed in claim 1 wherein: The blowing mechanism comprises a plurality of gas supply pipes (1204) connected in the rotating pipe (1201), a first connecting pipe (1205) in communication with the gas supply pipes (1204), and a jet pipe (1206) in communication with the first connecting pipe (1205); the gas supply pipes (1204) are arranged through the end of the rotating pipe (1201); the first connecting pipe (1205) is inserted in the rectangular cover (1203); the jet pipe (1206) is arranged through the rectangular cover (1203); the blowing mechanism further comprises a gas supply mechanism for supplying gas into the gas supply pipe (1204).

3. The process for preparing high purity cadmium powder as claimed in claim 2 wherein: The gas supply mechanism comprises a second air inlet pipe (201) connected with the shell (101), a first annular cover (202) in communication with the second air inlet pipe (201), and a rotating disc (203) rotating in the first annular cover (202); the rotating disc (203) is fixedly sleeved on the side wall of the gas supply pipe (1204); the gas supply mechanism further comprises a semicircular plate (204) connected with the first annular cover (202); the semicircular plate (204) can movably seal the gas supply pipe (1204).

4. The process for preparing high purity cadmium powder as claimed in claim 1 wherein: The circulating mechanism comprises a heat exchange cover (304) connected with the first air inlet pipe (105), two second annular covers (302) rotating on the side wall of the rotating pipe (1201), and a second connecting pipe (303) communicated between the second annular cover (302) and the heat exchange cover (304); the second annular cover (302) is in communication with the rotating pipe (1201) through a first through hole (301); the circulating mechanism further comprises a circulating pump (306) connected with 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 as claimed in claim 1 wherein: The device body further comprises a rotating mechanism for driving the gas nozzle (110) to rotate; the rotating mechanism comprises an annular groove (501) opened in the bottom of the partition plate (102), a rotating cover (502) in rotational connection with the annular groove (501), and a first driving assembly for driving the rotating cover (502) to rotate; the rotating cover (502) is in communication with the annular groove (501) through a second through hole (504); the annular groove (501) is in communication with the first gas inlet pipe (105); the rotating cover (502) comprises a conical surface (503); the gas nozzle (110) is connected with the conical surface (503) and is in communication with the inside of the rotating cover (502).

6. The process for preparing high purity cadmium powder as claimed in claim 5 wherein: The first driving assembly comprises a driven bevel gear (601) connected with the rotating cover (502), a driving bevel gear (603) in mesh 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 driving assembly further comprises a driven belt pulley (604) connected with the rotating rod (602), a double-groove belt pulley (605) connected with the rotating pipe (1201), and a belt (606) connected between the driven belt pulley (604) and the double-groove belt pulley (605).

7. The process for preparing high purity cadmium powder as claimed in claim 1 wherein: The device body further comprises a collecting mechanism for collecting high-purity cadmium powder; the collecting mechanism comprises a rotating filter cylinder (702) rotating at the bottom of the atomization chamber (104) and a second driving assembly for driving the rotating filter cylinder (702) to rotate; the rotating filter cylinder (702) comprises a conical filter hopper (701) and a discharge valve (107) communicated at the bottom of the conical filter hopper (701); the discharge valve (107) is connected with the bottom of the shell (101).

8. The process for preparing high purity cadmium powder as claimed in claim 7 wherein: The second driving assembly comprises a worm gear (801) connected with the rotating filter cylinder (702), a worm shaft (802) in mesh with the worm gear (801), and a rotating shaft (803) connected between the worm shaft (802) and the shell (101); the second driving assembly further comprises a second driving module for driving the rotating shaft (803) to rotate.

9. The process for preparing high purity cadmium powder as claimed in claim 7 wherein: The collecting mechanism further comprises a cleaning mechanism for cleaning the rotating filter cylinder (702); the cleaning mechanism comprises a scraper (901) connected with the inner wall of the shell (101); the scraper (901) comprises a vertical plate (902); the cleaning mechanism further comprises a moving frame (904), a rubber column (905) connected with the moving frame (904), and a moving assembly for driving the moving frame (904) to move back and forth.

10. The process for preparing high purity cadmium powder as claimed in claim 9 wherein: The moving assembly comprises a pushing block (1002), a connecting rod (1001) connected between the pushing block (1002) and the moving frame (904), and a spring telescopic rod (903) connected between the moving frame (904) and the shell (101); the moving assembly further comprises a cam (1003) connected with the rotating shaft (803), so that the pushing block (1002) can slide along the side wall of the cam (1003).

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