Magnesium smelting device based on microwave heating

Abstract

The invention relates to the technical field of magnesium smelting equipment, in particular to a magnesium smelting device based on microwave heating, which comprises a support frame divided into an upper layer and a lower layer, and further comprises a closed hood fixed on the support frame through a support rod; the multiple reduction assemblies are of the same structure and are installed in the closed cover in a penetrating mode, under the assistance of the reduction assemblies, high-purity alumina fibers are matched for isolating microwaves, the path of the microwaves in the device is limited, it is ensured that heat is efficiently utilized, and the magnesium output efficiency is improved; joints among parts, possibly affected by microwaves, of the device are sealed by high-temperature-resistant isolation materials, so that the microwaves are prevented from leaking, and meanwhile, a positive effect is maintained for a vacuum environment in the device; according to the device, multiple groups of microwave generators are matched with the silicon nitride furnace tubes, and the reduction assembly is combined, so that more raw materials can be smelted at a time, and the production efficiency is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of magnesium smelting equipment, and in particular to a magnesium smelting device based on microwave heating. Background Art

[0002] More than 90% of magnesium metal production in my country relies on the efficient Pidgeon process. However, the traditional Pidgeon process for magnesium refining has significant energy consumption and environmental challenges: to produce one ton of magnesium metal, up to 11 tons of dolomite, 0.2 tons of fluorite and 1.1 tons of ferrosilicon are required as reducing agents, accompanied by energy consumption of more than 5 tons of standard coal. This not only consumes a lot of resources, but also is limited by the characteristics of the process itself, with limited single-time production and low overall efficiency.

[0003] In view of this, technical personnel in the industry actively explored innovative paths and proposed the concept of applying microwave heating technology in the field of magnesium smelting, aiming to optimize the production process through technological innovation. Although this solution has achieved significant optimization of the process in theory, at the practical application level, there is still a lack of equipment and supporting devices that can fully demonstrate its superiority, making it difficult to effectively transform potential advantages into productivity. For this reason, we propose a device for magnesium smelting based on microwave heating. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a magnesium smelting device based on microwave heating, comprising a support frame, the support frame is divided into an upper and a lower layer, and further comprising: A closed cover, wherein the closed cover is fixed on the support frame through a support rod; A reduction assembly, wherein the reduction assembly has a plurality of components and has the same structure and is respectively installed through the interior of the closed cover; A plurality of microwave generators are provided in two rows and distributed on the upper and lower layers of the support frame, and the positions of the microwave generators on the upper layer of the support frame and the microwave generators on the lower layer correspond to each other one by one; A waveguide tube is installed on the microwave generator, all of the waveguide tubes are connected to one side of the closed cover, a waveguide slit antenna is installed through the waveguide tube, one side of the waveguide tube is fixed to the microwave generator by bolts, and the other side is located inside the closed cover, the waveguide slit antenna is located on the upper and lower sides of the reduction component, and clamps the reduction component.

[0005] In some embodiments, the reduction component includes a first water-cooled casting flange and a second bidirectional water-cooled casting flange installed on the closed cover, the first water-cooled casting flange is located on the outer wall on the opposite side of the waveguide tube, the second bidirectional water-cooled casting flange is located on the inner wall on the same side as the waveguide tube, and penetrates the corresponding side of the closed cover, a silicon nitride furnace tube is installed in the closed cover, and a third water-cooled casting flange and a fourth water-cooled casting flange are respectively sleeved on the silicon nitride furnace tube, the third water-cooled casting flange and the fourth water-cooled casting flange are respectively located on both sides of the silicon nitride furnace tube, the first water-cooled casting flange and the third water-cooled casting flange are fixed to one side of the silicon nitride furnace tube by bolts, the part of the second bidirectional water-cooled casting flange located inside the closed cover and the fourth water-cooled casting flange fix the other side of the silicon nitride furnace tube, and also include auxiliary components installed on the closed cover.

[0006] In some embodiments, carbon packing rings are fixed on both sides of the silicon nitride furnace tube, one of the carbon packing rings is fixed to one side of the first water-cooled casting flange on the side away from the silicon nitride furnace tube, and the other side of the other carbon packing ring is fixed to one side of the second bidirectional water-cooled casting flange.

[0007] In some embodiments, a heat shield is installed throughout the silicon nitride furnace tube. There are two heat shields, which are located at the two ends of the silicon nitride furnace tube respectively. The heat shield located near the first water-cooled casting flange is slidably connected to the inner wall of the silicon nitride furnace tube and is provided with a first through hole. There are several first through holes. The heat shield located near the second bidirectional water-cooled casting flange is fixedly connected.

[0008] In some embodiments, the auxiliary component includes a docking sleeve that passes through and is fixed on the first water-cooled casting flange, a first vacuum flange pipe fitting is connected and installed on one side of the docking sleeve, the first vacuum flange pipe fitting is externally connected to a vacuum system, a second vacuum flange is arranged on the top of the docking sleeve, a sealing cover is installed on the top of the docking sleeve, the sealing cover is connected to the docking sleeve through the second vacuum flange, and a fluororubber sealing ring is arranged at the connection with the docking sleeve, a limiting frame is slidingly arranged in the docking sleeve, a crystallization cylinder is fixed on the top of the limiting frame, and a crystallization filter plate is installed on the inner wall of one end of the crystallization cylinder connected to the limiting frame; It also includes a cooling jacket sleeved on the docking sleeve, an annular partition is fixed in the middle of the cooling jacket, a second through hole is opened on the annular partition, and there are a plurality of second through holes. The annular partition divides the cooling jacket into two connected cavities, and the two cavities are respectively connected with a water inlet pipe and a water outlet pipe, and the water inlet pipe and the water outlet pipe are both connected to the central water cooling circulation system.

[0009] In some embodiments, high-purity alumina fibers are disposed inside the enclosed cover, and the high-purity alumina fibers fill the rest of the space inside the enclosed cover except for the path between the waveguide slot antenna and the silicon nitride furnace tube.

[0010] In some embodiments, the second bidirectional water-cooled casting flange is connected to a sealing flange on the outer side of the closed cover, and a thermocouple is installed through the sealing flange. The number of the thermocouples is consistent with the silicon nitride furnace tube, one end of the thermocouple is located inside the silicon nitride furnace tube, and the thermocouple is electrically connected to the microwave generator of the upper and lower layers on the corresponding side.

[0011] In some embodiments, high-purity alumina fibers are placed inside the second bidirectional water-cooled casting flange.

[0012] In some embodiments, there are 10 sets of microwave generators, each set has a power of 25kw, and a microwave frequency of 915MHz.

[0013] In some embodiments, the inner diameter of the silicon nitride furnace tube is 260 mm and the length is 1600 mm, and the closed cover is 3000 mm in length, 1750 mm in width and 1200 mm in height.

[0014] The present invention has at least the following beneficial effects: 1. Under the action of multiple groups of microwave generators and the corresponding waveguide crack antennas, the generated microwaves are efficiently utilized. Under the action of the silicon nitride furnace tube, the microwaves are heated more evenly, which has a positive effect on the generation of magnesium vapor. In addition, the silicon nitride furnace tube has high density and high strength, which can ensure that the vacuum degree inside the device is extremely low during the entire refining process, thereby ensuring the quality of the produced magnesium; 2. With the assistance of the reduction component and the isolation of microwaves by high-purity alumina fibers, the path of microwaves inside the device is limited, ensuring efficient use of heat and improving the efficiency of magnesium production. The connections between parts of the device that may be affected by microwaves are sealed with high-temperature resistant insulation materials to prevent microwave leakage, while maintaining a positive effect on the vacuum environment inside the device. 3. In this device, through the cooperation between multiple groups of microwave generators and silicon nitride furnace tubes, combined with reduction components, more raw materials can be smelted at a time to ensure production efficiency; 4. The positions of the various components of this device are reasonably arranged, which saves space and is more convenient for the transportation and installation of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a schematic diagram of the local structure of the present invention; Figure 3 It is a schematic diagram of a partial cross-sectional structure of the present invention; Figure 4 This is a schematic diagram of the auxiliary component structure of the present invention; Figure 5 For the present invention Figure 4 Schematic diagram of the structure at A in the middle; Figure 6 It is a schematic diagram of the cross-sectional structure of the reduction assembly of the present invention; Figure 7 For the present invention Figure 6 Schematic diagram of the structure at B in the middle; Figure 8 For the present invention Figure 6 Schematic diagram of the structure at point C in the middle.

[0016] In the figure: 1, support frame; 2, closed cover; 21, high-purity alumina fiber; 3, reduction component; 31, first water-cooled casting flange; 32, second two-way water-cooled casting flange; 33, silicon nitride furnace tube; 34, third water-cooled casting flange; 35, fourth water-cooled casting flange; 300, auxiliary component; 301, docking sleeve; 302, first vacuum flange pipe; 303, second vacuum flange; 304, closed cover; 305, fluororubber sealing ring; 306, limit frame; 307, crystallization cylinder; 308, crystallization filter plate; 309, cooling jacket; 3010, annular partition; 3011, second through hole; 3012, water inlet pipe; 3013, water outlet pipe; 4, microwave generator; 41, waveguide; 42, waveguide crack antenna; 5, carbon packing ring; 61, heat shield; 62, first through hole; 71, sealing flange; 72, thermocouple. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0018] See also Figure 1-8 The present invention provides a technical solution: a magnesium smelting device based on microwave heating, comprising a support frame 1, the support frame 1 is divided into an upper and a lower layer, and further comprising: The sealed cover 2 is fixed on the support frame 1 through a support rod; There are several reduction components 3, and they have the same structure and are respectively installed in the closed cover 2; A plurality of microwave generators 4 are provided in two rows and are distributed on the upper and lower layers of the support frame 1, and the positions of the microwave generators 4 on the upper layer of the support frame 1 and the microwave generators 4 on the lower layer correspond to each other one by one; The waveguide tube 41 is installed on the microwave generator 4. All the waveguide tubes 41 are connected to one side of the closed cover 2. A waveguide slit antenna 42 is installed through the waveguide tube 41. One side of the waveguide tube 41 is fixed to the microwave generator 4 by bolts, and the other side is located inside the closed cover 2. The waveguide slit antenna 42 is located on the upper and lower sides of the reduction component 3 and clamps the reduction component 3.

[0019] The reduction component 3 includes a first water-cooled casting flange 31 and a second bidirectional water-cooled casting flange 32 installed on the closed cover 2, the first water-cooled casting flange 31 is located on the outer wall on the opposite side of the waveguide tube 41, the second bidirectional water-cooled casting flange 32 is located on the inner wall on the same side as the waveguide tube 41, and penetrates the corresponding side of the closed cover 2, a silicon nitride furnace tube 33 is installed in the closed cover 2, and a third water-cooled casting flange 34 and a fourth water-cooled casting flange 35 are respectively sleeved on the silicon nitride furnace tube 33, the third water-cooled casting flange 34 and the fourth water-cooled casting flange 35 are respectively located on both sides of the silicon nitride furnace tube 33, the first water-cooled casting flange 31 and the third water-cooled casting flange 34 are fixed to one side of the silicon nitride furnace tube 33 by bolts, the part of the second bidirectional water-cooled casting flange 32 located inside the closed cover 2 and the fourth water-cooled casting flange 35 are fixed to the other side of the silicon nitride furnace tube 33 by bolts, and also includes an auxiliary component 300 installed on the closed cover 2.

[0020] The first water-cooled casting flange 31 , the second bidirectional water-cooled casting flange 32 , the third water-cooled casting flange 34 and the fourth water-cooled casting flange 35 are all made of heat-resistant cast steel, which increases the stability of the equipment during operation.

[0021] Carbon packing rings 5 ​​are fixed on both sides of the silicon nitride furnace tube 33. One side of the carbon packing ring 5 away from the silicon nitride furnace tube 33 is fixed to one side of the first water-cooled casting flange 31, and the other side of the other carbon packing ring 5 is fixed to one side of the second two-way water-cooled casting flange 32.

[0022] The carbon packing ring 5 has good resistance to high temperature and high pressure, as well as excellent wear resistance and corrosion resistance, and has a stable sealing effect. When the raw materials are smelted inside the silicon nitride furnace tube 33, it is of great help to the vacuum inside the silicon nitride furnace tube 33, and will not be affected by the chemical reaction occurring during the smelting of the raw materials, which has a significant positive effect on the quality of the final magnesium product.

[0023] A heat shield 61 is installed throughout the silicon nitride furnace tube 33. There are two heat shields 61, which are located at the two ends of the silicon nitride furnace tube 33 respectively. The heat shield 61 located at one end close to the first water-cooled casting flange 31 is slidably connected to the inner wall of the silicon nitride furnace tube 33, and is provided with a first through hole 62. There are several first through holes 62. The heat shield 61 close to the second bidirectional water-cooled casting flange 32 is fixedly connected.

[0024] The heat shield 61 can prevent the heat in the silicon nitride furnace tube 33 from being lost significantly from both sides of the silicon nitride furnace tube 33. The first through hole 62 can ensure that the magnesium vapor can smoothly enter the crystallization tube 307. After the single furnace smelting is completed, the heat shield 61 that is slidably connected to the silicon nitride furnace tube 33 can be removed, which is convenient for removing the waste slag inside the silicon nitride furnace tube 33 and adding new raw materials.

[0025] The auxiliary component 300 includes a docking sleeve 301 that penetrates and is fixed on the first water-cooled casting flange 31, a first vacuum flange pipe 302 is connected and installed on one side of the docking sleeve 301, the first vacuum flange pipe 302 is externally connected to the vacuum system, a second vacuum flange 303 is arranged on the top of the docking sleeve 301, a sealing cover 304 is installed on the top of the docking sleeve 301, the sealing cover 304 is connected to the docking sleeve 301 through the second vacuum flange 303, and a fluororubber sealing ring 305 is arranged at the connection with the docking sleeve 301, a limiting frame 306 is slidably arranged in the docking sleeve 301, a crystallization cylinder 307 is fixedly installed on the top of the limiting frame 306, and a crystallization filter plate 308 is installed on the inner wall of the end where the crystallization cylinder 307 is connected to the limiting frame 306; It also includes a cooling jacket 309 sleeved on the docking sleeve 301, an annular partition 3010 is fixed in the middle of the cooling jacket 309, a second through hole 3011 is opened on the annular partition 3010, and there are a plurality of second through holes 3011. The annular partition 3010 and the second through holes 3011 divide the cooling jacket 309 into two connected cavities, and the two cavities are respectively connected with a water inlet pipe 3012 and a water outlet pipe 3013, and the water inlet pipe 3012 and the water outlet pipe 3013 are both connected to the central water cooling circulation system.

[0026] The water inlet pipe 3012 continuously supplies cold water to a cavity in the cooling jacket 309. Under the pressure provided by the central water cooling circulation system, the cold water enters another cavity through the second through hole 3011 on the annular partition 3010, and returns to the central water cooling circulation system from the water outlet pipe 3013 for cooling, so as to continuously reduce the temperature of the parts connected to the butt tube 301, so that the magnesium vapor is easier to crystallize in the crystallization tube 307. The limit frame 306 can prevent the negative pressure generated by the vacuum system from changing the position of the crystallization tube 307. It should be noted that the presence of the annular baffle 3010 and the second through hole 3011 slows down the water flow rate inside the cavity responsible for water inlet and performs diversion, ensuring that the water in the water inlet cavity of the cooling jacket 309 can evenly enter the water outlet cavity to evenly cool the crystallization tube 307.

[0027] High-purity alumina fibers 21 are arranged inside the sealed cover 2 , and the high-purity alumina fibers 21 fill the rest of the space inside the sealed cover 2 except for the path between the waveguide slot antenna 42 and the silicon nitride furnace tube 33 .

[0028] High-purity alumina fiber 21 has excellent heat resistance, thermal insulation, and chemical stability. It is widely used in modern industry and is easy to purchase. As a thermal insulation material, it can effectively prevent heat loss inside the silicon nitride furnace tube 33, and the heat is efficiently utilized, further shortening the time required for magnesium smelting.

[0029] The second bidirectional water-cooled casting flange 32 is located on the outer side of the closed cover 2 and is connected to a sealing flange 71. The sealing flange 71 is penetrated by a thermocouple 72. The number of the thermocouples 72 is consistent with the number of the silicon nitride furnace tubes 33. One end of the thermocouple 72 is located inside the silicon nitride furnace tube 33, and the thermocouple 72 is electrically connected to the microwave generator 4 on the upper and lower layers on the corresponding side.

[0030] The connection between the thermocouple 72 and the sealing flange 71 is welded, and the sealing flange 71 is airtight to further prevent microwave leakage and heat loss. The thermocouple 72 monitors the temperature inside the corresponding silicon nitride furnace tube 33 in real time. When the temperature inside the silicon nitride furnace tube 33 is too high or too low, the power of the corresponding microwave generator 4 is adjusted in real time to ensure that the temperature inside the silicon nitride furnace tube 33 is maintained within a suitable range.

[0031] High-purity alumina fiber 21 is placed inside the second two-way water-cooled casting flange 32 to prevent microwave leakage from the second two-way water-cooled casting flange 32, and at the same time, the bottom of the silicon nitride furnace tube is wrapped to prevent heat loss therefrom.

[0032] The working principle is as follows: before production, the staff opens the sealed cover 304, takes out the crystallization tube 307 through the limiting frame 306, then takes out the heat shielding plate 61 slidably connected to the silicon nitride furnace tube 33, adds raw materials into the silicon nitride furnace tube 33, and then resets the heat shielding plate 61 slidably connected to the silicon nitride furnace tube 33, the crystallization tube 307, and the limiting frame 306 in turn, and reseals the docking tube 301 through the sealed cover 304. One end of the limiting frame 306 is in contact with the inner side of the sealed cover 304. Even when the vacuum system draws negative pressure, the position of the crystallization tube 307 will not change. The vacuum value inside the device is continuously reduced through the vacuum system, and the central water-cooling circulation system continuously cools the butt joint 301 part. The microwave generator 4 is turned on. When the temperature inside the silicon nitride furnace tube 33 is too high or too low, the thermocouple 72 monitors and sends a signal to the corresponding microwave generator 4. The microwave generator 4 adjusts the power to ensure that the temperature inside the silicon nitride furnace tube 33 is maintained within a suitable range to reduce the raw materials. In this process, the first water-cooled casting flange 31, the second two-way water-cooled casting flange 32, the third water-cooled casting flange 34 and the fourth water-cooled casting flange 35 are all made of resistant Hot cast steel increases the stability of the equipment during operation. The carbon packing ring 5 has good high temperature and high pressure resistance, as well as excellent wear resistance and corrosion resistance, and has a stable sealing effect. When the raw materials are smelted inside the silicon nitride furnace tube 33, it is of great help to the vacuum inside the silicon nitride furnace tube 33, and will not be affected by the chemical reaction occurring during the smelting of the raw materials, which has a significant positive effect on the quality of the final magnesium product. The heat shield 61 can prevent the heat in the silicon nitride furnace tube 33 from being lost in large quantities from both sides of the silicon nitride furnace tube 33, and the first through hole 62 can ensure that the magnesium vapor can smoothly enter the crystallization tube 307. As the water inlet pipe 3012 continuously supplies cold water to a cavity in the cooling jacket 309, the cold water enters another cavity through the second through hole 3011 on the annular partition 3010 under the pressure provided by the central water cooling circulation system, and returns to the central water cooling circulation system from the water outlet pipe 3013 for cooling, the temperature of the parts of the docking tube 301 is continuously reduced, so that the magnesium vapor is easier to crystallize in the crystallization tube 307. The high-purity alumina fiber 21 has excellent heat resistance, heat insulation, and chemical stability. As a heat preservation material, it can effectively prevent the heat loss inside the silicon nitride furnace tube 33, and the heat is efficiently used, further shortening the time required for magnesium smelting. Finally, the device can restore higher quality magnesium in a shorter time; After the smelting is completed, the staff opens the sealed cover 304, takes out the crystallization tube 307 through the limit frame 306, then takes out the heat shield plate 61 which is slidably connected to the silicon nitride furnace tube 33, removes and collects the magnesium in the crystallization tube 307, takes out the waste slag in the silicon nitride furnace tube 33, and then re-adds raw materials into the silicon nitride furnace tube 33, and resets the heat shield plate 61 which is slidably connected to the silicon nitride furnace tube 33, the crystallization tube 307 and the limit frame 306 in turn, re-seals the docking tube 301 through the sealed cover 304, and smelting can be carried out again. Example 2

[0033] Based on Example 1, this application further optimizes the present invention: There are 10 sets of microwave generators 4, each set has a power of 25kw and a microwave frequency of 915MHz.

[0034] The inner diameter of the silicon nitride furnace tube 33 is 260 mm and the length is 1600 mm. The closed cover 2 is 3000 mm in length, 1750 mm in width and 1200 mm in height.

[0035] The device is set up with the above data, which is more convenient for transportation and installation. Traditional box transport vehicles can be used for transportation. Multiple groups can operate at the same time, and the production efficiency can also be guaranteed. After testing, the raw material processing capacity of a single silicon nitride furnace tube 33 in this device is 480kg, and the crude magnesium output is 72kg. Five furnaces can be operated at the same time in this device, that is, the single raw material processing capacity of this device is 2400kg, and the crude magnesium output is 360kg. When the raw material smelting temperature is 1100℃, compared with the 12 hours required for traditional Pijiang method smelting, this device only takes 4 hours to complete, and the maximum operating temperature of this device is 1450℃. As the temperature rises, the reduction time of a single furnace is 1-4 hours, which greatly improves production efficiency.

[0036] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0037] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A magnesium smelting device based on microwave heating, comprising a support frame (1), wherein the support frame (1) is divided into two layers, an upper layer and a lower layer, and is characterized in that: Also includes: A closed cover (2), wherein the closed cover (2) is fixed to the support frame (1) via a support rod; A reduction assembly (3), wherein the reduction assembly (3) is provided in a plurality and has the same structure and is respectively installed through the interior of the closed cover (2); A plurality of microwave generators (4) are provided in two rows and are distributed on the upper and lower layers of the support frame (1), and the positions of the microwave generators (4) located on the upper layer of the support frame (1) and the microwave generators (4) located on the lower layer correspond to each other one by one; A waveguide tube (41), wherein the waveguide tube (41) is installed on the microwave generator (4), all of the waveguide tubes (41) are in communication with one side of the sealed cover (2), a waveguide slit antenna (42) is installed through each of the waveguide tubes (41), one side of the waveguide tube (41) is fixed to the microwave generator (4) by bolts, and the other side is located inside the sealed cover (2), and the waveguide slit antenna (42) is respectively located on the upper and lower sides of the reduction component (3) and clamps the reduction component (3).

2. The device for magnesium smelting based on microwave heating according to claim 1, characterized in that: The reduction assembly (3) comprises a first water-cooled casting flange (31) and a second bidirectional water-cooled casting flange (32) mounted on the sealed cover (2); the first water-cooled casting flange (31) is located on the outer wall on the side opposite to the waveguide tube (41); the second bidirectional water-cooled casting flange (32) is located on the inner wall on the same side as the waveguide tube (41), and penetrates the corresponding side of the sealed cover (2); a silicon nitride furnace tube (33) is installed in the sealed cover (2), and a third water-cooled casting flange (34) and a fourth water-cooled casting flange (32) are respectively sleeved on the silicon nitride furnace tube (33); The invention also comprises a second bidirectional water-cooled casting flange (35), the third water-cooled casting flange (34) and the fourth water-cooled casting flange (35) are respectively located on both sides of the silicon nitride furnace tube (33), the first water-cooled casting flange (31) and the third water-cooled casting flange (34) are fixed to one side of the silicon nitride furnace tube (33) by bolts, the second bidirectional water-cooled casting flange (32) is located inside the closed cover (2) and the fourth water-cooled casting flange (35) are fixed to the other side of the silicon nitride furnace tube (33) by bolts, and also comprises an auxiliary component (300) installed on the closed cover (2).

3. The device for magnesium smelting based on microwave heating according to claim 2, characterized in that: Carbon packing rings (5) are fixed to both sides of the silicon nitride furnace tube (33), wherein the side of one carbon packing ring (5) away from the silicon nitride furnace tube (33) is fixed to one side of the first water-cooled casting flange (31), and the other side of the other carbon packing ring (5) is fixed to one side of the second bidirectional water-cooled casting flange (32).

4. The device for magnesium smelting based on microwave heating according to claim 2, characterized in that: A heat shield (61) is installed through the silicon nitride furnace tube (33). There are two heat shields (61), which are respectively located at the two ends of the silicon nitride furnace tube (33). The heat shield (61) located on the side close to the first water-cooled casting flange (31) is slidably connected to the inner wall of the silicon nitride furnace tube (33) and is provided with a first through hole (62). There are a plurality of first through holes (62). The heat shield (61) located on the side close to the second bidirectional water-cooled casting flange (32) is fixedly connected.

5. The device for magnesium smelting based on microwave heating according to claim 2, characterized in that: The auxiliary component (300) comprises a docking tube (301) penetrating and fixed on a first water-cooled casting flange (31); a first vacuum flange pipe fitting (302) is connected and installed on one side of the docking tube (301); the first vacuum flange pipe fitting (302) is externally connected to a vacuum system; a second vacuum flange (303) is arranged at the top of the docking tube (301); a sealing cover (304) is installed at the top of the docking tube (301); the sealing cover (304) is connected to the docking tube (301) through the second vacuum flange (303); and a fluororubber sealing ring (305) is arranged at the connection with the docking tube (301); a limiting frame (306) is slidably arranged inside the docking tube (301); a crystallization tube (307) is fixedly installed on the top of the limiting frame (306); and a crystallization filter plate (308) is installed on the inner wall of one end of the crystallization tube (307) connected to the limiting frame (306); It also includes a cooling jacket (309) sleeved on the docking sleeve (301), an annular partition (3010) is fixed in the middle of the cooling jacket (309), the annular partition (3010) is provided with second through holes (3011), there are a plurality of second through holes (3011), the annular partition (3010) divides the cooling jacket (309) into two connected cavities, and the two cavities are respectively connected with a water inlet pipe (3012) and a water outlet pipe (3013).

6. The device for magnesium smelting based on microwave heating according to claim 2, characterized in that: High-purity alumina fibers (21) are arranged inside the sealed cover (2), and the high-purity alumina fibers (21) fill the rest of the space inside the sealed cover (2) except for the path between the waveguide slot antenna (42) and the silicon nitride furnace tube (33).

7. The device for magnesium smelting based on microwave heating according to claim 2, characterized in that: The second bidirectional water-cooled casting flange (32) is located on the outer side of the closed cover (2) and is connected to a sealing flange (71). The sealing flange (71) is penetrated by a thermocouple (72). The number of the thermocouples (72) is consistent with the number of the silicon nitride furnace tubes (33). One end of the thermocouple (72) is located inside the silicon nitride furnace tube (33), and the thermocouple (72) is electrically connected to the microwave generator (4) on the upper layer and the lower layer on the corresponding side.

8. The device for magnesium smelting based on microwave heating according to claim 2, characterized in that: High-purity alumina fibers (21) are placed inside the second bidirectional water-cooled casting flange (32).

9. The device for magnesium smelting based on microwave heating according to claim 1, characterized in that: There are 10 sets of microwave generators (4), each set has a power of 25 kW and a microwave frequency of 915 MHz.

10. The device for magnesium smelting based on microwave heating according to claim 2, characterized in that: The silicon nitride furnace tube (33) has an inner diameter of 260 mm and a length of 1600 mm, and the closed cover (2) has a length of 3000 mm, a width of 1750 mm, and a height of 1200 mm.

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