High-purity rare earth metal preparation device and preparation process

Abstract

The invention relates to the technical field of rare earth molten salt electrolysis, and discloses a high-purity rare earth metal preparation device and process, the high-purity rare earth metal preparation device comprises a furnace body, a furnace cover is detachably mounted on the furnace body, the center of the furnace cover is provided with a circular material port, and a liftable cathode rod is inserted at the material port; four anode seats are connected to the groove of the furnace cover, and anode assemblies are fixed to the anode seats through U-shaped clamps; the side wall of the furnace cover is connected with a copper bar; a cooling cavity is formed in the side wall of the furnace cover, and the side wall of the furnace cover is connected with a side plate for sealing the cooling cavity; the furnace cover is cooled through a cooling gas path and a cooling water path; a graphite mat felt is placed between the furnace cover and the furnace body, and an inner hole of the graphite mat felt corresponds to the circular material opening; by combining two cooling modes of cooling gas and the cooling water pipe, the temperature of the furnace cover can be effectively reduced, safe and stable operation of equipment is ensured, the service life of the equipment is prolonged, meanwhile, the sealing performance of the furnace cover is prevented from being affected by high-temperature deformation, efficient and high-purity preparation of rare earth metal is achieved, and the product quality and the production safety are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of rare earth molten salt electrolysis, and in particular to a high-purity rare earth metal preparation device and preparation process. Background Art

[0002] The existing method for producing rare earth metals and alloys is mainly the fluoride molten salt system oxide electrolysis method, which uses rare earth oxide-fluoride (rare earth fluoride + lithium fluoride) as the electrolysis system. In a molten state, with a graphite plate as the anode and a tungsten rod as the cathode, under the action of direct current, the rare earth oxide is decomposed into oxygen ions and rare earth metal ions. The oxygen ions lose electrons at the anode and react with graphite to form carbon monoxide or carbon dioxide, while the rare earth metal ions gain electrons at the cathode and are reduced to rare earth metals.

[0003] Existing devices face significant technical bottlenecks in cooling system design, with the core issues centered around a single cooling method and insufficient heat dissipation efficiency. Most devices rely solely on water cooling, which offers relatively high heat exchange efficiency. However, the water pipes are often arranged in straight lines or simple coils, lacking a targeted water flow path and failing to precisely cool critical heated areas of the furnace roof (such as the junction between the grooved concrete layer and the anode seat). In terms of heat dissipation efficiency, the single cooling method results in a significant mismatch between the heat dissipation rate of the furnace cover and the heat generation rate of the electrolysis process. When the device operates for extended periods, the furnace cover temperature continues to rise, exceeding the material's tolerance limit and easily causing structural deformation. This deformation directly damages the seal between the graphite felt and the furnace body, allowing outside air to infiltrate the furnace. This not only exacerbates material oxidation and reduces product purity, but can also cause safety hazards such as arc short circuits. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-purity rare earth metal preparation device and preparation process to solve the problems of single furnace cover cooling method and insufficient heat dissipation efficiency proposed in the above background technology.

[0005] The technical solution adopted by the present invention is as follows: a high-purity rare earth metal preparation device, comprising a furnace body and a furnace cover detachably mounted on the furnace body; the furnace cover is square, with a circular material port provided in the center, a cathode rod inserted into the material port; a groove is provided on the top surface of the furnace cover, a concrete layer is poured in the groove, an anode seat arranged at equal angles is connected to the groove, an anode assembly is fixed to the anode seat by a U-shaped clip; a copper bus is connected to the side wall of the furnace cover, and a cooling cavity is provided in the side wall of the furnace cover, the cooling cavity is closed by a side plate, a first pipe body for injecting cooling gas and a second pipe body for discharging cooling gas are connected to the side plate; The first tube body and the second tube body in the furnace cover are provided with air hole flow channels arranged at equal angles, and a partition is connected to the cooling cavity, which divides the cooling cavity into two parts, one part corresponds to the first tube body, and the other part corresponds to the second tube body, so that the cooling gas fills the cooling cavity and is discharged through the second tube body; a pipe clamp is provided in the cooling cavity, and the pipe clamp is provided with equally spaced slots, and a spiral cooling water pipe is coiled in the slot, and the inlet end and the discharge end of the cooling water pipe pass through the first tube body and the second tube body respectively; an annular graphite pad is placed between the furnace cover and the furnace body, and the inner hole of the graphite pad corresponds to the circular material port.

[0006] Further, the stirring head includes a hexagonal seat, which is connected to three support rods arranged at equal angles, and the free end of the support rod is connected to the cup body of the T-shaped rotating part; the small diameter end of the cup body is connected to the seventh branch pipe, and the seventh branch pipe is connected to a conical filter screen, and the small diameter end of the conical filter screen is connected to the tube seat, and a filter plate is fixed to the tube seat by a clamping ring, and the end surface of the filter plate is provided with a first sliding hole arranged at equal angles, and a first guide rod is slidably connected in the first sliding hole, and the right end of the first guide rod is connected to a fixing plate, and a telescopic gap is formed between the fixing plate and the filter plate, and the side wall of the first guide rod is sleeved with a first spring located between the filter plate and the fixing plate, and the end surface of the fixing plate is fixed with a first push rod corresponding to the filter holes of the filter plate, and the end surface of the fixing plate has an arc groove.

[0007] Furthermore, a preparation process using the high-purity rare earth metal preparation device comprises the following steps: Electrolytic furnace smelting: Place the cerium-containing rare earth raw material in a graphite crucible with an inner diameter of 50 cm and a height of 80 cm. Pass argon gas for protection, maintain the furnace pressure at 0.12 MPa, apply 8-12V DC voltage and 1500A current for electrolytic smelting at 1450℃±10℃ for 2 hours; Pouring into the mold: After the raw materials are melted and impurities are removed, the molten metal is sucked into a rectangular mold (20 cm long × 10 cm wide × 5 cm high) coated with a high-temperature resistant release agent at a speed of 50g / s; Cooling molding: First, force air cooling at a wind speed of 8m / s for 10 minutes, then water cooling at 20℃ and a flow rate of 2L / min for 2 hours to room temperature; Block cutting: Use 0.5mm diamond cutting wire at a speed of 10cm / min and a pressure of 0.3MPa to cut into 5cm×3cm×2cm small blocks with a cutting accuracy of ±0.1mm; Edge and corner burr grinding: Use 80 mesh (1500r / min, 3 minutes), 120 mesh (1200r / min, 2 minutes), 200 mesh (1200r / min, 2 minutes), and 400 mesh (1200r / min, 3 minutes) sandpaper to grind until the surface roughness Ra ≤ 0.8μm; Packaging: The product is placed in an anti-static packaging bag containing desiccant, and then packed into a carton filled with cushioning foam. The outside of the box is labeled with the name, specifications, weight, production date, and batch number. Factory: Inspection of appearance, size, purity, qualified products are shipped according to order, and unqualified products are reworked.

[0008] The beneficial effects of the present invention are: the high-purity rare earth metal preparation device achieves significant technical effects through multi-dimensional innovative design: the U-shaped positioning seat of the furnace cover and the furnace body is connected with the insulating plate to ensure the installation coaxiality and electrical safety, the multi-layer furnace body structure is combined with the thermal insulation carbon felt to improve energy utilization, and the arc-shaped graphite trough optimizes the electrolysis reaction space; the cooling system ensures the cleanliness of the cooling air through spiral water pipes and purification boxes for multi-stage filtration, preventing high-temperature deformation of the furnace cover and product contamination; the temperature detection structure monitors the temperature of the graphite trough in real time to avoid abnormalities affecting production; the anti-oxidation sealing system uses a motor to drive the fan plate and the air sealing plate combination to reduce material oxidation, and cooperates with the annular cover to discharge flue gas; the plug-in fixing method of the anode assembly is convenient for maintenance, and the cathode rod insulation structure ensures safe operation; the compound movement of the stirring rod eliminates the dead zone of the metal solution flow, and the stirring head integrated filtration structure improves the purity, ultimately achieving efficient, high-purity and safe preparation of rare earth metals. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a schematic diagram of the main structure of this application.

[0010] Figure 2 This is a schematic diagram of the three-dimensional structure of this application.

[0011] Figure 3 This is a schematic diagram of the main cross-sectional structure of this application.

[0012] Figure 4 Schematic diagram of the three-dimensional structure of the furnace cover.

[0013] Figure 5 It is a schematic diagram of the top cross-sectional structure of the cooling water pipe.

[0014] Figure 6 It is a schematic diagram of the top cross-sectional structure of the first tube body and the second tube body.

[0015] Figure 7 It is a schematic diagram of the main cross-sectional structure of the furnace body.

[0016] Figure 8 It is a schematic diagram of the three-dimensional structure of the first positioning seat.

[0017] Figure 9 Schematic diagram of the three-dimensional structure of the anode assembly.

[0018] Figure 10 This is a schematic diagram of the main cross-sectional structure of the temperature measuring hole.

[0019] Figure 11 It is a schematic diagram of the main cross-sectional structure of the flip cover.

[0020] Figure 12 Schematic diagram of the side structure of the guide bar.

[0021] Figure 13 Schematic diagram of the three-dimensional structure of the annular cover.

[0022] Figure 14 Schematic diagram of the three-dimensional structure of the fan-shaped plate.

[0023] Figure 15 Schematic diagram of the three-dimensional structure of the inner circle.

[0024] Figure 16 Schematic diagram of the three-dimensional structure of the ring gear.

[0025] Figure 17 Schematic diagram of the three-dimensional structure of the rack.

[0026] Figure 18 Schematic diagram of the three-dimensional structure of the rack and fan-shaped plate.

[0027] Figure 19 It is a schematic diagram of the side cross-sectional structure of the C-type plate.

[0028] Figure 20 Schematic diagram of the three-dimensional structure of the arc cover.

[0029] Figure 21 It is a schematic diagram of the side cross-sectional structure of the purification box.

[0030] Figure 22 Schematic diagram of the three-dimensional structure of the purification box.

[0031] Figure 23 It is a schematic diagram of the side cross-sectional structure of the plastic-fired board.

[0032] Figure 24 Schematic diagram of the three-dimensional structure of the substrate.

[0033] Figure 25 This is a schematic diagram of the main structure of the third gear.

[0034] Figure 26 Schematic diagram of the three-dimensional structure of the stirring head.

[0035] Figure 27 It is a schematic diagram of the side cross-sectional structure of the conical filter.

[0036] Figure 28 It is a schematic diagram of the side cross-sectional structure of the tube seat.

[0037] Figure 29 Schematic diagram of the top cross-sectional structure of the first push rod.

[0038] Figure 30 Schematic diagram of the three-dimensional structure of the fixed plate.

[0039] In the figure: 1. furnace body; 2. furnace cover; 3. circular material port; 4. cathode rod; 5. groove; 6. concrete layer; 7. anode seat; 8. U-shaped clamp; 9. anode assembly; 10. copper busbar; 11. cooling cavity; 12. side plate; 13. first tube body; 14. second tube body; 15. pipe clamp; 16. clamping groove; 17. cooling water pipe; 18. graphite felt; 19. outer steel cylinder; 20. refractory brick; 21. inner steel cylinder; 22. thermal insulation carbon felt; 23. carbon ramming material layer; 24. graphite tank body; 26. first positioning seat; 27. first notched groove; 28. second positioning seat; 29. ​​second notched groove; 30. connecting bolt; 31. insulating plate; 32. bearing seat; 33. horizontal plate; 34 , vertical plate; 35, curved plate; 36, open slot; 37, anode plate; 38, temperature measuring hole; 39, first branch pipe; 40, second branch pipe; 41, sinking trough; 42, hinged ear; 43, flip cover; 44, limit slot; 45, third branch pipe; 46, end cover; 47, wire hole; 48, first telescopic rod; 49, slip ring; 50, guide bar; 51, thermocouple; 52, annular cover; 53, fourth branch pipe; 54, fifth branch pipe; 55, sixth branch pipe; 56, first bearing ring; 57, second bearing ring; 58, gear ring; 59, first worm gear; 60, first worm; 61, first motor; 62, second gear; 63, rack; 64, sector plate; 65, annular carrier plate; 66, inner Ring; 67. Guide rail; 68. Air sealing plate; 69. Arc cover; 70. C-shaped plate; 71. Flange; 72. Fastening bolts; 73. Purification box; 74. Air outlet; 75. Air inlet; 76. Plastic sintering plate; 77. Upper filter disc; 78. Lower filter disc; 79. Connecting column; 80. Secondary filter chamber; 81. First inner filter disc; 82. Second inner filter disc; 83. Primary filter chamber; 84. Slide rail; 85. Slide seat; 86. Carrying frame; 87. Second telescopic rod; 88. Third telescopic rod; 89. Base plate; 90. Guide rod; 91. Base; 92. Third bearing seat; 93. Third gear; 94. Stirring rod; 95. Limiting strip; 96. Stirring head; 97. Hexagonal seat; 98. Support rod; 99. Cup body; 100. Seventh branch pipe; 101. Conical filter screen; 102. Tube seat; 103. Snap ring; 104. Filter plate; 105. First sliding hole; 106. First guide rod; 107. Fixing plate; 108. Telescopic gap; 109. First spring; 110. First push rod; 111. Arc groove; 112. Partition; 113. Plug; 133. Fourth gear; 134. Second motor; 135. Fourth bearing seat; 136. Second worm; 137. Second worm gear; 138. Fifth bearing seat; 139. First rocker arm; 140. Connecting rod; 141. Sixth bearing seat; 142. Fifth gear; 143. Second rocker arm; 144. Sleeve; 145. Tooth groove. DETAILED DESCRIPTION

[0040] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0042] In addition, the terms "first", "second", "third", "fourth", "fifth", "sixth", "seventh", "eighth", "ninth" and "tenth" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features.

[0043] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "install", "connect" and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] like Figures 1 to 6As shown in the embodiment 1, a high-purity rare earth metal preparation device includes a furnace body 1, a furnace cover 2 is detachably mounted on the furnace body 1, the furnace cover 2 is square in shape, and a circular material port 3 is provided in the center of the furnace cover 2, a cathode rod 4 that can be lifted and lowered is inserted into the material port; the top surface of the furnace cover 2 has a groove 5, a concrete layer 6 is poured in the groove 5; four anode seats 7 arranged at equal angles are connected to the groove 5, the anode seat 7 is L-shaped, an anode assembly 9 is fixed to the anode seat 7 by a U-shaped clip 8, the opening of the U-shaped clip 8 has an inclined surface, and the opening of the U-shaped clip 8 is plugged and adapted to the anode seat 7; a copper bus 10 is connected to the side wall of the furnace cover 2; the side wall of the furnace cover 2 has a There is a cooling cavity 11, and the side wall of the furnace cover 2 is connected to a side plate 12 that closes the cooling cavity 11; the side plate 12 is connected to a first tube body 13 and a second tube body 14, the first tube body 13 is used to inject cooling air, and the second tube body 14 is used to discharge cooling air. The first tube body 13 and the second tube body 14 located in the furnace cover 2 have air holes arranged at equal angles. Preferably, the number of air holes on the first tube body 13 is greater than or equal to the number of air holes on the second tube body 14. For example, the number of air holes on the first tube body 13 is 8, and the number of air holes on the second tube body 14 is 6. A partition 112 is connected to the cooling cavity 11. 112 divides the cooling cavity 11 into two parts, one part corresponds to the first tube body 13, and the other part corresponds to the second tube body 14, so that after the cooling gas fills the cooling cavity 11, it is discharged through the second tube body 14, which can overcome the rapid discharge of the cooling gas from the adjacent second tube body 14 and ensure the cooling effect; further, the air hole flow channel can be threadedly connected to the plug 113, which can be purchased and obtained. The plug 113 can adjust the air intake and air outlet to ensure that the cooling gas fills the cooling cavity 11, and the arrangement of the cooling water pipe 17 can guide the cooling gas flow path to produce a good cooling effect; the cooling cavity 11 is equipped with equiangular A pipe clamp 15 is arranged, and an air gap is left between the top surface of the pipe clamp 15 and the furnace cover 2. The pipe clamp 15 has slots 16 opened at equal intervals, and a spirally arranged cooling water pipe 17 is coiled in the slot 16. The inlet end of the cooling water pipe 17 passes through the first tube body 13, and the gap between the inlet end of the cooling water pipe 17 and the first tube body 13 is used for the flow of cooling gas; the discharge end of the cooling water pipe 17 passes through the second tube body 14, and the gap between the discharge end of the cooling water pipe 17 and the second tube body 14 is used for the discharge of cooling gas; a graphite felt pad 18 is placed between the furnace cover 2 and the furnace body 1. The shape of the graphite felt pad 18 is annular, and the inner hole of the graphite felt pad 18 corresponds to the circular material port 3. Movement process: The cathode rod 4 can move up and down at the circular material port 3; the U-shaped clamp 8 is plugged into the anode seat 7 through the inclined surface at its opening to achieve the fixation and removal of the anode assembly 9; the cooling water pipe 17 is coiled in the clamping groove 16 of the pipe clamp 15, and the cooling air enters the cooling cavity 11 from the first tube body 13 and is then discharged from the second tube body 14. The cooling water and cooling air cool the furnace cover 2 at the same time.Beneficial effects: The lifting and lowering of the cathode rod 4 facilitates material addition and equipment operation; the plug-in adaptation design of the U-shaped card 8 and the anode seat 7 makes the installation and disassembly of the anode assembly 9 more convenient; the combination of the two cooling methods of cooling air and cooling water pipe 17 can effectively reduce the temperature of the furnace cover 2, ensure the safe and stable operation of the equipment, extend the service life of the equipment, and prevent the furnace cover 2 from deforming due to high temperature and affecting the sealing performance.

[0045] like Figure 7 As shown, as an optimization of Example 1, the furnace body 1 includes an outer steel cylinder 19, the inner bottom surface of the outer steel cylinder 19 is paved with refractory bricks 20, an inner steel cylinder 21 is placed on the refractory bricks 20, the upper edge of the inner steel cylinder 21 protrudes outside the outer steel cylinder 19, and an insulating carbon felt 22 is provided between the inner steel cylinder 21 and the outer steel cylinder 19; a carbon ramming material layer 23 is provided in the inner steel cylinder 21, a graphite trough body 24 is provided in the carbon ramming material layer 23, and the inner bottom surface of the graphite trough body 24 is arc-shaped; there is a gap between the inner wall of the graphite trough body 24 and the anode assembly 9; the graphite trough body 24 is flush with the carbon ramming material layer 23 and the upper edge of the inner steel cylinder 21, and the upper edge is used to place the graphite pad felt 18. Beneficial effects: Multi-layer structure design, refractory bricks 20 provide high temperature protection, and thermal insulation carbon felt 22 reduces heat loss and improves energy utilization efficiency; the curved bottom surface of the graphite trough 24 is conducive to the aggregation of materials and electrolytic reaction, and the gap between it and the anode assembly 9 ensures the normal progress of the electrolysis process, thereby improving electrolysis efficiency and product quality.

[0046] like Figure 8 As shown, as an optimization of the first embodiment, the outer wall of the outer steel cylinder 19 is connected to a first positioning seat 26, the number of which is four, and the first positioning seats 26 are arranged at equal angles, the shape of the first positioning seat 26 is U-shaped, and the top surface of the first positioning seat 26 is provided with a first notch groove 27; the bottom surface of the furnace cover 2 is connected to a second positioning seat 28, the shape of the second positioning seat 28 is U-shaped, and the bottom surface of the second positioning seat 28 is provided with a second notch groove 29, and the second notch groove 29 is connected to the first notch groove 27 by a connecting bolt 30, and the connecting bolt 30 is sleeved with two insulating plates 31, and the two insulating plates 31 are located inside the first positioning seat 26 and the second positioning seat 28. Movement process: The second positioning seat 28 of the furnace cover 2 is connected to the first positioning seat 26 of the furnace body 1 by the connecting bolt 30 to achieve the fixation of the furnace cover 2 and the furnace body 1. When disassembling, just unscrew the connecting bolt 30. Beneficial effects: The design of the U-shaped positioning seat and the notch groove facilitates the precise positioning of the furnace cover 2 and the furnace body 1, ensuring the coaxiality and stability of the installation of the two; the insulating plate 31 sleeved on the connecting bolt 30 can effectively prevent current leakage, ensure the safety of the operator, and avoid damage to other parts of the equipment due to current conduction.

[0047] like Figure 9As shown, as an optimization of Example 1, the anode assembly 9 includes a support base 32, which is composed of a horizontal plate 33, a vertical plate 34, and a curved plate 35. The horizontal plate 33 is in contact with the top surface of the furnace cover 2 and has an open slot 36 that plugs into the anode seat 7. The horizontal plate 33 is squeezed and fixed with a U-shaped clamp 8. The side of the horizontal plate 33 is connected to the vertical plate 34, and the bottom of the vertical plate 34 is connected to the curved plate 35. The curved plate 35 is connected to an anode plate 37 via bolts. The anode plate 37 is in an arc shape and is used to extend into the graphite tank body 24 to heat the material. Movement process: The horizontal plate 33 of the support base 32 of the anode assembly 9 is in contact with the top surface of the furnace cover 2 and is squeezed and fixed to the anode seat 7 via the U-shaped clamp 8. The anode plate 37 is fixed to the curved plate 35 via bolts and extends into the graphite tank body 24. Beneficial effects: The structural design of the anode assembly 9 ensures the stable position of the anode plate 37 during the electrolysis process, can evenly heat the material in the graphite trough 24, enable the material to be fully electrolyzed, and improve the purity and yield of rare earth metals; the plug-in adaptation of the horizontal plate 33 and the anode seat 7 and the fixing method of the U-shaped card facilitate the installation, replacement and maintenance of the anode assembly 9.

[0048] like Figures 10 to 12As shown, as an optimization of the first embodiment, considering that the existing furnace body 1 does not have a means of temperature detection and is prone to leakage, a temperature measuring hole 38 is opened on the side of the outer steel cylinder 19, and the temperature measuring hole 38 passes through the thermal insulation carbon felt 22, the inner steel cylinder 21, and the carbon ramming material layer 23, and the temperature measuring hole 38 is opposite to the graphite trough 24; a first branch pipe 39 is welded to the side wall of the outer steel cylinder 19, and the first branch pipe 39 corresponds to the temperature measuring hole 38; a second branch pipe 40 is connected to the first branch pipe 39 by a countersunk bolt, and a sink 41 is opened at one end of the second branch pipe 40, and a hinged ear 42 is installed in the sinking groove 41, and a flip cover 43 is rotatably connected to the hinged ear 42, and the initial opening of the flip cover 43 The state is vertical, the flip cover 43 is used to close the second branch pipe 40, the pipe mouth of the first branch pipe 39 will not form structural interference with the flip cover 43, the other end of the second branch pipe 40 is provided with a limit groove 44, the limit groove 44 is used for the position of the slip ring 49; the second branch pipe 40 is connected to the third branch pipe 45, the free end of the third branch pipe 45 is connected to the end cover 46, the end cover 46 is provided with a wire hole 47, the inner side of the end cover 46 is connected to the first telescopic rod 48, the piston end of the first telescopic rod 48 is connected to the slip ring 49, and the inner wall of the third branch pipe 45 is provided with a guide bar 50 for guiding the movement of the slip ring 49; a thermocouple 51 is installed on the slip ring 49, and the thermocouple 51 is used to push open the flip plate for temperature measurement. Movement process: The thermocouple 51 is installed on the slip ring 49. When temperature measurement is required, the first telescopic rod 48 pushes the slip ring 49 to move along the guide strip 50 on the inner wall of the third branch pipe 45. The thermocouple 51 pushes open the flip cover 43 and measures the temperature of the graphite tank body 24 through the temperature measuring hole 38. After the temperature measurement is completed, the first telescopic rod 48 is retracted, the slip ring 49 and thermocouple 51 are reset, and the flip cover 43 relies on its own gravity or other reset structure to reseal the second branch pipe 40 to prevent high temperature from damaging the thermocouple 51. Beneficial effect: This temperature detection structure can monitor the temperature of the graphite tank body 24 in the furnace body 1 in real time, detect temperature anomalies in a timely manner, and avoid affecting product quality and equipment safety due to excessively high or low temperatures. The design of the flip cover 43 can prevent external impurities from entering the temperature measuring hole 38, ensuring the accuracy of temperature measurement while protecting the thermocouple 51 from damage.

[0049] like Figures 13 to 19As shown, as an optimization of Example 1, considering that oxidation will occur during the electrolysis of materials, the top surface of the furnace cover 2 is connected with an annular cover 52, the annular cover 52 is concentric with the furnace cover 2, and the annular cover 52 is located on the outside of the anode seat 7; the side wall of the annular cover 52 is connected with a fourth branch pipe 53 for exhausting flue gas; the side wall of the annular cover 52 is connected with a fifth branch pipe 54, the fifth branch pipe 54 is located at a tangential position of the annular cover 52, the free end of the fifth branch pipe 54 is connected with a sixth branch pipe 55, and the sixth branch pipe 55 is connected to the cooling cavity 11; the top surface of the annular cover 52 is fixed with a first bearing ring 56 and a second bearing ring 57 by bolts, and a gear ring 58 is rotatably connected between the first bearing ring 56 and the second bearing ring 57, and the outer tooth surface of the gear ring 58 is meshed with a first worm gear 59, and the first worm gear 5 9 is meshed with a first worm 60, which is driven by a first motor 61; the inner tooth surface of the ring gear 58 is meshed with a second gear 62 arranged at equal angles, and the number of the second gears 62 is 6, and the second gear 62 is meshed with a rack 63, and the top surface of the rack 63 is connected to a fan-shaped plate 64 by bolts. The 6 fan-shaped plates 64 can form a circular plate to close the material opening; the bottom surface of the first bearing ring 56 is connected to an annular carrier plate 65, and the annular carrier plate 65 is connected to an inner ring 66, and the inner hole of the inner ring 66 is the same as the diameter of the material opening, and the top surface of the second bearing ring 57 and the inner ring 66 are installed with a guide rail 67 for guiding the movement of the rack 63; further, considering the sealing type of the fan-shaped plate 64, the second bearing seat and the inner ring 66 are installed with an air sealing plate 68, and the shape of the air sealing plate 68 is arc-shaped. Movement process: The first motor 61 drives the first worm 60 to rotate, the first worm 60 drives the first worm wheel 59, and the first worm wheel 59 drives the ring gear 58 to rotate; the inner tooth surface of the ring gear 58 drives the second gear 62 to rotate, and the second gear 62 drives the rack 63 to move, so that the fan plate 64 slides on the guide rail 67 to realize the opening and closing of the material port; when the fan plate 64 closes the material port, the air sealing plate 68 plays a sealing role to reduce oxidation. Beneficial effects: The setting of the annular cover 52, the fourth branch pipe 53 and the fifth branch pipe 54 can effectively discharge the flue gas generated during the electrolysis process and keep the furnace environment clean; the fan plate 64 automatically closes the material port through the motor and gear transmission, which improves the automation level of the equipment, reduces the contact between the material and the air, reduces the degree of oxidation, and improves the purity of the product; the air sealing plate 68 and the arc cover 69 further enhance the sealing effect to ensure anti-oxidation performance.

[0050] like Figure 20 As shown, as an optimization of embodiment 1, considering the sealing performance of the sector plate 64 , the outer side surface of the sector plate 64 is connected with an arc cover 69 , and six arc covers 69 can form a circular ring structure, and the arc cover 69 is adapted to the outer side wall of the annular cover 52 .

[0051] like Figure 19As shown, as an optimization of the first embodiment, considering the insulation between the sector plate 64 and the cathode rod 4, a C-shaped plate 70 is fixed to the side wall of the cathode rod 4 by a fastening bolt 72. The C-shaped plate 70 is made of insulating material. There are two C-shaped plates 70, which are fastened together to form a tubular structure. The side wall of the C-shaped plate 70 has flanges 71 arranged symmetrically in the upper and lower parts. The flanges 71 are used to install the fastening bolts 72. Movement process: The two C-shaped plates 70 are fastened to the side wall of the cathode rod 4 by the fastening bolts 72 to form a tubular insulating structure. Beneficial effect: The insulation design of the C-shaped plate 70 effectively prevents leakage between the cathode rod 4 and other components, ensuring the safe operation of the equipment; the provision of the flange 71 and the fastening bolts 72 makes the installation and removal of the C-shaped plate more convenient, and facilitates the maintenance and inspection of the cathode rod 4.

[0052] like Figures 21 to 23 As shown, as an optimization of the embodiment, considering that the cleanliness of the cooling air will affect the quality of the product, a purification box 73 is installed in the cooling cavity 11, and the purification box 73 has an air outlet 74 connected to the sixth branch pipe 55, and the purification box 73 has air inlet holes 75 arranged at equal intervals. A plastic-sintered plate 76 is installed in the purification box 73, and the plastic-sintered plate 76 includes an upper filter 77 and a lower filter 78. The upper filter 77 and the lower filter 78 are connected by multiple connecting columns 79 in the middle, separating multiple secondary filter cavities 80; the inner wall of the secondary filter cavity 80 is provided with a first inner filter 81 and a second inner filter 82, and the first inner filter 81 and the second inner filter 82 are inscribed in the position of the connecting column 79 to form a primary filter cavity 83, and the primary filter cavity 83 corresponds to the air inlet hole 75; the upper filter 77, the lower filter 78, the first inner filter 81, the second inner filter 82 and the connecting column 79 in the middle are formed in one step. Movement process: A portion of the cooling air in the cooling cavity 11 enters from the air inlet 75 of the purification box 73, passes through the primary filter chamber 83 and the secondary filter chamber 80 in sequence, and is filtered by the upper filter disc 77, the lower filter disc 78, the first inner filter disc 81 and the second inner filter disc 82 of the sintering plate 76. Finally, it is discharged from the air outlet 74 into the sixth branch pipe 55 and the fifth branch pipe 54, and then enters the annular cover 52 to form a spiral airflow, further reducing oxidation. Argon can be selected as the cooling gas. Beneficial effects: The configuration of the purification box 73 and the sintering plate 76 can effectively filter impurities in the cooling air, ensure the cleanliness of the cooling air, and prevent impurities from entering the furnace and affecting product quality. The multi-layer filter structure design of the sintering plate 76 improves the filtration efficiency and accuracy, and can effectively intercept impurity particles of different particle sizes.

[0053] like Figure 24-25As shown, as an optimization of the first embodiment, considering that the alloy uniformity is poor after the material is melted and there is a flow dead zone, a top surface of a sector plate 64 is connected to a slide rail 84, a slide seat 85 is slidably connected to the slide rail 84, and a carrier 86 is connected to the slide seat 85. The carrier 86 is driven by a second telescopic rod 87, and the second telescopic rod 87 can control the stirring rod 94 to move closer to or away from the center of the material port; a third telescopic rod 88 is installed on the carrier 86, and the piston end of the third telescopic rod 88 is connected to a base plate 89, and a guide rod 89 is slidably connected to the base plate 89. Rod 90, the lower end of the guide rod 90 is connected to the carrier 86; a base 91 is installed on the base plate 89, and a third bearing seat 92 is installed on the base 91. The number of the third bearing seats 92 is 2, and the third bearing seat 92 is rotatably connected to the third gear 93. The third gear 93 is slidably connected to the stirring rod 94. The side wall of the stirring rod 94 has a limit bar 95 that limits the stirring rod 94 from sliding up and down; the lower end of the stirring rod 94 is connected to a stirring head 96, which is used to extend into the graphite tank 24 to stir the metal solution; the third gear 93 is meshed with a fourth gear 133, the fourth gear 133 is driven by a second motor 134, and the second motor 134 is connected to the base 91; the fourth gear 133 is rotatably connected to a fourth bearing seat 135, and the fourth bearing seat 135 is connected to the base 91, and the shaft end of the fourth gear 133 is connected to a second worm 136, and the second worm 136 is meshed with a second worm wheel 137, and the second worm wheel 137 is rotatably connected to a fifth bearing seat 138, and the fifth bearing seat 138 is connected to the base 91, and the axis of the second worm wheel 137 is connected to the shaft end of the second gear 133. It is connected to a first rocker arm 139, the free end of the first rocker arm 139 is rotatably connected to a connecting rod 140, a sixth bearing seat 141 is mounted on the base 91, the sixth bearing seat 141 is rotatably connected to a fifth gear 142, the center of the fifth gear 142 is connected to a second rocker arm 143, the free end of the second rocker arm 143 is rotatably connected to the free end of the connecting rod 140; the side wall of the stirring rod 94 is connected to a sleeve 144, the side wall of the sleeve 144 has teeth 145 arranged at equal intervals, and the teeth 145 are engaged with the fifth gear 142. Movement process: The second telescopic rod 87 drives the carrier 86 to slide on the slide rail 84, causing the stirring rod 94 to move closer to or further away from the center of the material inlet; the second motor 134 drives the fourth gear 133 to rotate, which in turn drives the third gear 93, which in turn drives the stirring rod 94 to rotate via the limit bar 95. Simultaneously, the fourth gear 133 drives the fifth gear 142 to rotate via the second worm gear 136, the second second worm gear 137, the first rocker arm 139, the connecting rod 140, and the second rocker arm 143. The fifth gear 142 drives the stirring rod 94 up and down via the tooth groove 145, thus achieving a compound movement of the stirring rod 94. Beneficial effect: The compound movement of the stirring rod 94 can effectively stir the metal solution, eliminate dead zones in the flow, improve the uniformity of the alloy, and enhance product quality. The slide rail 84 of this structure can be directly installed on the furnace cover 2.

[0054] like Figure 26 As shown, as an optimization of the first embodiment, the stirring head 96 includes a hexagonal seat 97, and the hexagonal seat 97 is connected to three support rods 98 arranged at equal angles. The free ends of the support rods 98 are connected to a cup body 99, and the cup body 99 is in the shape of a T-shaped rotating part.

[0055] like Figures 27 to 30 As shown, as an optimization of the first embodiment, the small diameter end of the cup body 99 is connected to the seventh branch pipe 100, and the seventh branch pipe 100 is connected to a conical filter 101, which is used to filter impurities. Preferably, the small diameter end of the conical filter 101 is connected to a tube seat 102, and the tube seat 102 is connected to a filter plate 104 through a clamping ring 103. The end surface of the filter plate 104 is provided with first sliding holes 105 arranged at equal angles; a first guide rod 106 is slidably connected in the first sliding hole 105; the right end of the first guide rod 106 is connected to A fixed plate 107 is provided, forming a telescopic gap 108 between the fixed plate 107 and the filter plate 104. A first spring 109, made of a ceramic spring, is sheathed on the sidewall of the first guide rod 106 and elastically positioned between the filter plate 104 and the fixed plate 107. Uniformly spaced first push rods 110 are fixed to the end surface of the fixed plate 107, corresponding one-to-one with the filter holes of the filter plate 104 and used to penetrate the holes. The end surface of the fixed plate 107 has an arcuate groove 111. Movement process: When the stirring rod 94 rotates, the metal solution flows through the small-diameter end of the conical filter screen 101, where large impurities are intercepted by the screen. Fluctuations in solution pressure or stirring vibrations cause the filter plate 104 to slide along the first guide rod 106, compressing or releasing the first spring 109, causing the first push rods 110 to periodically penetrate the filter holes. The arc-shaped groove 111 creates a vortex on the end surface of the fixed plate 107, enhancing the separation of impurities and preventing them from clogging the filter holes. Beneficial Effects: Self-Cleaning Mechanism: The reciprocating motion of the spring-driven push rod automatically clears the filter holes, extending the life of the filter and reducing the frequency of downtime for maintenance.

[0056] Furthermore, a preparation process using a high-purity rare earth metal preparation device is proposed, which specifically includes the following steps: (1) Electrolytic Furnace Melting: Cerium-containing rare earth raw materials are placed in a specially designed inert anode electrolytic furnace. The furnace uses a graphite crucible with an inner diameter of 50 cm and a height of 80 cm as a container for the raw materials. Argon is introduced into the electrolytic furnace as a shielding gas. The operating temperature of the electrolytic furnace is set at 1450°C. A DC voltage is applied through the electrodes within a controlled range of 8-12V and a current of 1500A for electrolytic melting. During the melting process, the furnace temperature is monitored in real time using thermocouples to ensure that the temperature fluctuation range is within ±10°C. Melting is continued for 2 hours to fully melt the raw materials. (2) Pouring into the Mold: Once the raw materials are completely melted, they are cleaned of impurities and then drawn into the cooled mold using an electromagnetic pump. The mold is rectangular, with internal dimensions of 20 cm long, 10 cm wide, and 5 cm high. A high-temperature release agent is applied to the mold surface to facilitate demolding after molding. During the draw process, the speed is controlled at 50 g / s to avoid splashing and bubbles. (3) Cooling and Molding: The mold containing the molten rare earth metal cerium is transferred to a cooling chamber, which uses a combination of forced air and water cooling. First, the forced air cooling system is activated at a speed of 8m / s. Cooling is performed for 10 minutes to achieve initial solidification of the metal surface. The water cooling system is then activated, with the cooling water temperature controlled at 20°C and a flow rate of 2L / min. Cooling is continued for 2 hours until the rare earth metal cerium in the mold is completely cooled and formed. After cooling, the temperature of the metal block drops to room temperature (25°C). (IV) Block Cutting: A high-precision CNC cutting machine is used to cut the cooled rare earth metal cerium block into small pieces. According to product specifications, the metal block is cut into small pieces measuring 5 cm long, 3 cm wide, and 2 cm high. During the cutting process, a 0.5 mm diameter diamond cutting wire is used, with a cutting speed of 10 cm per minute and a cutting pressure of 0.3 MPa to ensure a smooth cut surface and a cutting accuracy error within ±0.1 mm. (5) Deburring of Edges and Corners: Place the cut rare earth metal cerium blocks on an automatic grinder for deburring of edges and corners. The grinder is equipped with sandpaper of varying grits. Initially, use 80-grit coarse sandpaper for preliminary grinding to remove larger burrs and unevenness. The grinding speed is 1500 r / min for 3 minutes. Then, fine grinding is performed using 120-grit, 200-grit, and 400-grit sandpaper, respectively. The grinding speed for each grit size is 1200 r / min, and the grinding time is 2 minutes, 2 minutes, and 3 minutes, respectively, until the surface roughness of the metal block reaches Ra0.8μm or less. (VI) Packaging: Place the polished rare earth metal cerium product in a specially designed antistatic bag. Each bag contains a desiccant to prevent moisture and oxidation during storage and transportation. The bags are then neatly placed in a cardboard box, which is padded with cushioning foam to protect the product from damage during transportation. A product label is affixed to the outside of the box, indicating the product name, specifications, weight, production date, and batch number. (VII) Shipment: Final quality inspection of packaged products, including appearance, dimensions, purity, and other indicators. Products that pass the inspection are shipped out of the factory according to the order requirements; those that fail the inspection are returned to the corresponding process for rework. Although the present invention has been described in detail with reference to the foregoing examples, it is still possible for those skilled in the art to make modifications to the technical solutions described in the foregoing embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-purity rare earth metal preparation device, characterized in that: The invention comprises a furnace body (1) and a furnace cover (2) detachably mounted on the furnace body (1); the furnace cover (2) is square, and a circular material opening (3) is provided in the center, and a cathode rod (4) is inserted into the material opening; a groove (5) is provided on the top surface of the furnace cover (2), a concrete layer (6) is poured in the groove (5), and anode seats (7) arranged at equal angles are connected to the groove (5), and an anode assembly (9) is fixed to the anode seat (7) by a U-shaped clip (8); a copper busbar (10) is connected to the side wall of the furnace cover (2), and a cooling cavity (11) is provided in the side wall of the furnace cover (2), and the cooling cavity (11) is closed by a side plate (12), and a first pipe body (13) for injecting cooling gas and a second pipe body (14) for discharging cooling gas are connected to the side plate (12); the first pipe body (13) located in the furnace cover (2) ) and the second tube body (14) have air hole flow channels arranged at equal angles, and a partition (112) is connected to the cooling cavity (11), and the partition (112) divides the cooling cavity (11) into two parts, one part corresponds to the first tube body (13), and the other part corresponds to the second tube body (14), so that the cooling gas fills the cooling cavity (11) and is discharged through the second tube body (14); a pipe clamp (15) is provided in the cooling cavity (11), and a spiral cooling water pipe (17) is coiled in the clamping groove (16) of the pipe clamp (15), and the inlet end and the outlet end of the cooling water pipe (17) pass through the first tube body (13) and the second tube body (14) respectively; an annular graphite pad (18) is placed between the furnace cover (2) and the furnace body (1), and the inner hole of the graphite pad (18) corresponds to the circular material port (3).

2. The high-purity rare earth metal preparation device according to claim 1, characterized in that: The furnace body (1) comprises an outer steel cylinder (19), the inner bottom surface of the outer steel cylinder (19) is paved with refractory bricks (20), an inner steel cylinder (21) is placed on the refractory bricks (20), the upper edge of the inner steel cylinder (21) protrudes from the outer steel cylinder (19), and a thermal insulation carbon felt (22) is filled between the inner and outer steel cylinders (19); a carbon ramming material layer (23) and a graphite trough (24) are provided in the inner steel cylinder (21), the graphite trough (24) is flush with the carbon ramming material layer (23) and the upper edge of the inner steel cylinder (21), and the upper edge is used to place the graphite felt (18).

3. The high-purity rare earth metal preparation device according to claim 1, characterized in that: The outer wall of the outer steel cylinder (19) is provided with a U-shaped first positioning seat (26) at equal angles, and a first notch groove (27) is opened on the top surface; the bottom surface of the furnace cover (2) is connected to the U-shaped second positioning seat (28), and a second notch groove (29) is opened on the bottom surface. The two notches are connected by connecting bolts (30), and the bolts are sleeved with two insulating plates (31) and are located in the positioning seat.

4. The high-purity rare earth metal preparation device according to claim 1, characterized in that: The anode assembly (9) includes a supporting base (32) consisting of a horizontal plate (33), a vertical plate (34) and an arc-shaped plate (35). The horizontal plate (33) is in contact with the top surface of the furnace cover (2) and has an open groove (36) adapted to be plugged into the anode seat (7). The horizontal plate (33) is fixed by squeezing with a U-shaped clip (8). The horizontal plate (33) is connected to the vertical plate (34), the vertical plate (34) is connected to the arc-shaped plate (35), and the arc-shaped plate (35) is connected to the arc-shaped anode plate (37) by bolts.

5. The high-purity rare earth metal preparation device according to claim 2, characterized in that: A temperature measuring hole (38) is provided on the side of the outer steel cylinder (19), which passes through the heat-insulating carbon felt (22), the inner steel cylinder (21) and the carbon ramming material layer (23) and is opposite to the graphite tank body (24); a corresponding first branch pipe (39) is provided on the side wall of the outer steel cylinder (19), the first branch pipe (39) is connected to the second branch pipe (40), one end of the first branch pipe (39) is provided with a hinged ear (42) in a recessed groove (41) and is rotatably connected to a flip cover (43), and the other end of the first branch pipe (40) is provided with a limit groove (44); the second branch pipe (40) is connected to the third branch pipe (45), the free end is connected to the end cover (46), the end cover (46) is provided with a first telescopic rod (48), the piston end is connected to a slip ring (49), the slip ring (49) moves along the guide strip (50) on the inner wall of the third branch pipe (45), and a thermocouple (51) is provided on the slip ring (49) for opening the flip cover (43) to measure the temperature.

6. The high-purity rare earth metal preparation device according to claim 1, characterized in that: The top surface of the furnace cover (2) is connected to the concentric annular cover (52) and is located outside the anode seat (7). The side wall is connected to the fourth branch pipe (53) and the tangential fifth branch pipe (54) for exhausting flue gas. The fifth branch pipe (54) is connected to the sixth branch pipe (55) and communicates with the cooling cavity (11); the top surface of the annular cover (52) is provided with the first and second bearing rings, and the first and second bearing rings are rotatably connected to the gear ring (58). The outer tooth surface meshes with the first worm wheel (59) and the first worm (60) driven by the first motor (61); the inner tooth surface meshes with 6 second gears (62) with equal angles, the second gear (62) meshes with the rack (63), and the top surface of the rack (63) is connected to the fan-shaped plate (64). The bottom surface of the first bearing ring (56) is connected to the annular carrier plate (65) and the inner ring (66), and the top surface of the second bearing ring (57) and the inner ring (66) is equipped with a guide rail (67) of the guide rack (63), and an arc-shaped air sealing plate (68) is provided.

7. The high-purity rare earth metal preparation device according to claim 1, characterized in that: The side wall of the cathode rod (4) is fixed with two insulating C-shaped plates (70) by fastening bolts (72), and the two plates are buckled into a tubular shape. The side wall of the C-shaped plate (70) is provided with upper and lower symmetrical flanges (71) for mounting bolts.

8. The high-purity rare earth metal preparation device according to claim 6, characterized in that: A purification box (73) is provided in the cooling cavity (11), and the purification box (73) has an air outlet (74) connected to the sixth branch pipe (55) and air inlet holes (75) arranged at equal intervals. A plastic sintering plate (76) is provided in the purification box (73), and the plastic sintering plate (76) includes an upper filter (77) and a lower filter (78). The upper filter (77) and the lower filter (78) are connected in the middle by a plurality of connecting columns (79), which separate a plurality of secondary filter plates. A filter cavity (80); the inner wall of the secondary filter cavity (80) is provided with a first inner filter disc (81) and a second inner filter disc (82); the first inner filter disc (81) and the second inner filter disc (82) are inscribed at the position of the connecting column (79) to form a primary filter cavity (83) corresponding to the air inlet hole (75); the upper filter disc (77), the lower filter disc (78), the first inner filter disc (81), the second inner filter disc (82) and the connecting column (79) are a one-piece molding structure.

9. The high-purity rare earth metal preparation device according to claim 6, characterized in that: A slide rail (84) is provided on the top surface of one of the fan-shaped plates (64), and a slide seat (85) is connected to a carrier (86) driven by a second telescopic rod (87); the carrier (86) is connected to a base plate (89) through a third telescopic rod (88), and the base plate (89) is slidably connected to a guide rod (90), and the lower end of the guide rod (90) is fixed to the carrier (86); the base plate (89) is provided with a base (91), and the two The third bearing seat (92) is rotatably connected to the third gear (93), and the third gear (93) is slidably connected to the stirring rod (94). The side wall of the stirring rod (94) is provided with a limit bar (95), the lower end of which is connected to the stirring head (96); the third gear (93) is engaged with the fourth gear (133) driven by the second motor (134), and the fourth gear (133) is fixed to the base (91) through the fourth bearing seat (135), and the shaft end of the fourth gear (133) is connected to the second worm (136); the second worm (136) is engaged with the second worm wheel (137), and the second worm wheel (137) The fifth bearing seat (138) is fixed to the base (91), and its axis is connected to the first rocker arm (139). The first rocker arm (139) is hinged to the second rocker arm (143) through the connecting rod (140). A sixth bearing seat (141) is installed on the base (91). The sixth bearing seat (141) is rotatably connected to the fifth gear (142). The second rocker arm (143) at the center of the fifth gear (142) is hinged to the connecting rod (140). The sleeve (144) on the side wall of the stirring rod (94) is engaged with the fifth gear (142) through the tooth groove (145).

10. A preparation process using the high-purity rare earth metal preparation device according to any one of claims 1 to 9, characterized in that: The following steps are involved: Electrolytic furnace smelting: Place the cerium-containing rare earth raw materials in a graphite crucible, introduce argon protection, and electrolyze; Pouring into mold: After the raw materials are melted, impurities are removed and the molten metal is sucked into the mold; Cooling molding: first cooled by forced air, then cooled to room temperature by water; Block cutting: cutting into small pieces using diamond cutting wire; Edge and corner burr grinding: Use 80 mesh, 120 mesh, 200 mesh, and 400 mesh sandpaper in sequence to grind until the surface roughness Ra ≤ 0.8μm.

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