A device and method for temperature and pressure dual control in silicon thermal magnesium smelting

Abstract

The present invention relates to the technical field of primary magnesium smelting, and particularly relates to a temperature and pressure dual-control device and method for silicon thermal magnesium smelting. The temperature and pressure dual-control device for silicon thermal magnesium smelting includes a reduction pot and a cooler. A hollow frustum-shaped temperature-adjusting transition cylinder is arranged between the pot mouth of the reduction pot and the cooler. The small-diameter end of the hollow frustum-shaped temperature-adjusting transition cylinder is fixedly connected to the end face of the pot mouth of the reduction pot, and the large-diameter end of the hollow frustum-shaped temperature-adjusting transition cylinder is fixedly connected to the cooler. A gradient condensation assembly is arranged inside the pot mouth of the reduction pot. A crystallizer is arranged inside the cooler, and one end of the crystallizer abuts against the inner wall of the hollow frustum-shaped temperature-adjusting transition cylinder. The present invention also discloses a usage method of the temperature and pressure dual-control device for silicon thermal magnesium smelting. The temperature and pressure dual-control device and method provided by the present invention can regulate the local partial pressure and temperature of magnesium vapor without significantly increasing the flow resistance of magnesium vapor, stably prepare metallic magnesium with a purity of Mg9995A or above, have a high output, and are simple in production operation.

Description

Technical Field

[0001] The invention relates to the technical field of raw magnesium smelting, and in particular to a temperature-pressure dual-control device and method for silicon hot magnesium smelting. Background Art

[0002] The vacuum silicon thermal method is the main production method of magnesium in my country. Its core process includes: grinding and mixing the three raw materials of calcined dolomite, ferrosilicon and fluorite according to the ratio, pressing them into "date-shaped" balls of about 3-5 cm, filling them into cylindrical reduction tanks in a stacked manner, and reacting CaO+MgO+Si→CaO under vacuum of about 20Pa and high temperature of about 1200℃. 2 SiO 4 +Mg(g), and then magnesium vapor escapes from the reduction tank and condenses into crude magnesium in the crystallizer. However, since magnesium vapor often contains vapor impurities and particulate impurities, the prepared metal raw magnesium still faces the chronic problem of a wide variety of impurity content and large fluctuations, which is easy to deteriorate the performance of downstream magnesium and magnesium alloys, making it difficult to meet application needs.

[0003] In order to prepare high-purity raw magnesium, the prior art usually places a filter at the mouth of the reduction tank (between the reduction tank and the crystallizer) in order to intercept vapor impurities and particulate impurities to a certain extent. For example, patent CN201821258683.0 discloses a crude magnesium crystallization fireproof filter, but the device can only make the raw magnesium purity reach the requirement of Mg9995B. Patents CN202122215954.2, CN202122215953.8 and CN202111071001.1 use more complex flow channel designs to filter impurities in magnesium vapor while increasing the heat resistance effect. Although it achieves a good purification effect, it significantly increases the structural resistance of the filter fire baffle, so that the generated magnesium vapor has no time to escape, which brings changes in production costs and operations: First, the magnesium vapor that does not have time to escape will hinder the forward progress of the silicon thermal magnesium smelting chemical reaction, affecting the output of crude magnesium; secondly, this part of the magnesium vapor increases the magnesium partial pressure on the ball side of the filter fire baffle, so that the actual partial pressure of the magnesium vapor is greater than the saturated vapor pressure at the corresponding temperature and condenses on the fire baffle, increasing the difficulty of removing and cleaning the device; thirdly, in order to prevent the magnesium vapor from depositing on the filter fire baffle, the temperature of the filter fire baffle is often increased, but because the filter fire baffle is in direct contact with the crystallizer under conventional settings, this operation will simultaneously increase the temperature of the crystallizer, causing the crystallized magnesium to ignite and burn. The above series of problems are caused by the addition of the filter fire baffle, which has a large air resistance, breaking the original dynamic balance and matching relationship between the temperature and pressure of the magnesium vapor in the system, and the new balance constructed is difficult to meet the actual production needs.

[0004] In view of this, it is necessary to provide a device and a method for temperature and pressure dual control in silicon thermal magnesium smelting, so as to efficiently remove impurities without significantly increasing air resistance and establish a suitable temperature and pressure matching relationship, and truly realize the stable preparation of magnesium metal with a purity of Mg9995A or above without affecting the output and operation. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a device and a method for temperature and pressure dual control in silicon thermal magnesium smelting. The device and method provided by the present invention can efficiently remove impurities without significantly increasing air resistance. At the same time, the device can effectively establish the temperature and pressure balance of the vacuum silicon thermal reduction system, and will not cause problems in production operations such as crystallization of magnesium vapor on the filter interceptor, making it difficult to remove the filter interceptor, or ignition of crystalline magnesium during vacuum breaking, providing technical support for low-cost large-scale production of high-quality magnesium with a purity of Mg9995A or above.

[0006] The purpose of the present invention is to provide a device for temperature and pressure dual control in silicon thermal magnesium smelting.

[0007] Another purpose of the present invention is to provide a method for using the device for temperature and pressure dual control in silicon thermal magnesium smelting.

[0008] According to the device for temperature and pressure dual control in silicon thermal magnesium smelting provided by the specific embodiment of the present invention, it includes a reduction tank and a cooler. A hollow frustum-shaped temperature-adjusting transition cylinder is arranged between the tank mouth of the reduction tank and the cooler. The small-diameter end of the hollow frustum-shaped temperature-adjusting transition cylinder is fixedly connected to the end face of the tank mouth of the reduction tank, and the large-diameter end of the hollow frustum-shaped temperature-adjusting transition cylinder is fixedly connected to the cooler;

[0009] A gradient condensation component is arranged inside the tank mouth of the reduction tank;

[0010] A crystallizer is arranged inside the cooler, and one end of the crystallizer abuts against the inner wall of the hollow frustum-shaped temperature-adjusting transition cylinder.

[0011] In a conventional magnesium smelting device using the silicon thermal method, the reduction pot is directly connected to the cooler, or there is a short cylindrical transition zone between the reduction pot and the cooler; the larger-diameter end of the crystallizer in the cooler is often limited by being close to the connection between the mouth of the reduction pot and the cooler. On the one hand, the relative position between the crystallizer and the cooler during limitation mainly affects the cooling capacity of magnesium vapor. In actual production, since the short cylindrical transition zone near the reduction pot will be worn, it will tend to become shorter and shorter, and the cooler will get closer and closer to the reduction pot, and the relative position between the cooler and the crystallizer limited at the mouth of the reduction pot will also get closer and closer; this will make the temperatures at the mouth of the reduction pot and the crystallizer difficult to control and unstable. On the other hand, if a filter is placed at the mouth of the reduction pot, the filter will be in direct contact with the crystallizer; when adjusting the temperature, the filter and the crystallizer have the same temperature and face the situation of rising and falling together. When the temperature of the filter rises, the synchronous increase in the temperature of the crystallizer will cause the crystallized magnesium inside it to catch fire; and if in order to avoid fire and reduce the temperature of the crystallizer, the temperature of the filter will also be reduced synchronously, causing magnesium vapor to deposit on the filter. In the present invention, by connecting a hollow frustum-shaped transition cylinder between the mouth of the reduction pot and the cooler, the smaller-diameter end of the frustum-shaped transition cylinder is connected to the end face of the mouth of the reduction pot, and the larger-diameter end is connected to the cooler, and the large end face of the crystallizer in the cooler abuts against the inner wall of the frustum-shaped transition cylinder; on the one hand, the position of the crystallizer is mainly limited by the diameter of its large end and the diameter of the inner wall of the frustum-shaped transition cylinder. Even if the connection between the frustum-shaped transition cylinder and the reduction pot is worn and the cooler gets closer to the mouth of the reduction pot, the limitation of the crystallizer is determined by the inner wall of the frustum-shaped transition cylinder, and the position relative to the cooler remains constant, and the cooling capacity is stable. On the other hand, due to the limitation of the frustum-shaped transition cylinder, the distance between the crystallizer and the mouth of the reduction pot is still 10 - 100 mm. When a filter is placed at the mouth of the pot, the filter and the crystallizer will not be in direct contact, and the temperatures between the two are different and the interference is relatively small. When the temperature of the filter is raised so that it does not deposit magnesium, due to the temperature difference between the filter and the crystallizer, the temperature of the crystallizer only rises slightly and does not cause fire.

[0012] According to the silicon thermal method magnesium smelting temperature and pressure dual-control device provided by the specific embodiment, the distance between the larger-diameter end of the crystallizer and the gradient condensation component is 10 - 100 mm.

[0013] According to the silicon thermal method magnesium smelting temperature and pressure dual-control device provided by the specific embodiment, the gradient condensation component includes a first heat insulation plate, a second heat insulation plate, a third heat insulation plate and a protection plate;

[0014] The first heat insulation plate is in the shape of a bow larger than a semi - circle with the chord facing upwards; the first heat insulation plate and the third heat insulation plate are arranged in parallel. The protection plate is connected between the lower end of the first heat insulation plate and the third heat insulation plate, and the protection plate, the first heat insulation plate and the third heat insulation plate enclose a gradient condensation channel. Positioning notches are provided at both ends of the protection plate, and the edge of the second heat insulation plate is snap - fitted with the positioning notches;

[0015] The second heat insulation plate includes an upper semi - circular plate and a lower semi - drum plate. The lower straight edge of the upper semi - circle is integrally connected to the top straight edge of the lower semi - drum plate. The radius of the lower semi - drum plate is equal to the inner arc diameter of the protection plate, and the radius of the upper semi - circular plate is not less than the radius of the lower semi - circle;

[0016] The second heat insulation plate is arranged in parallel with the first heat insulation plate and the third heat insulation plate, and the lower end of the second heat insulation plate extends into the gradient condensation channel;

[0017] The side surface of the second heat insulation plate is hermetically connected to both ends of the protection plate, and a gap is provided between the lower end of the second heat insulation plate and the bottom wall of the gradient condensation channel;

[0018] Through holes are provided on the third heat insulation plate. The shape of the third heat insulation plate is circular. The side of the protection plate away from the third heat insulation plate is fixedly connected to the arc - shaped edge of the first heat insulation plate.

[0019] According to the silicon thermal magnesium smelting temperature - pressure dual - control device provided by the specific embodiment of the present invention, a limiting flanging for abutted cooperation with the end face of the tank mouth of the reduction tank is radially extended at the edge of the third heat insulation plate.

[0020] According to the silicon thermal magnesium smelting temperature - pressure dual - control device provided by the specific embodiment of the present invention, a filter screen is arranged between the third heat insulation plate and the second heat insulation plate.

[0021] According to the method for silicon thermal magnesium smelting temperature - pressure dual - control provided by the specific embodiment of the present invention, the above - mentioned silicon thermal magnesium smelting temperature - pressure dual - control device is used for magnesium smelting;

[0022] The method includes the following steps:

[0023] (1) One end of the reduction tank of the silicon thermal magnesium smelting temperature - pressure dual - control device is placed in the reduction furnace. Charge the reduction tank with material balls containing CaO, MgO, Si and CaF 2 The filling termination position of the material balls is 0 - 200 mm away from the gradient condensation component. Then, the gradient condensation component and the crystallizer are sequentially loaded and sealed;

[0024] (2) Evacuate the entire silicon thermal magnesium smelting silicon thermal reduction device to < 20 Pa, control the wall temperature of the reduction tank charging area to rise to 1100 - 1300 °C, and start the silicon thermal magnesium smelting production;

[0025] (3) After the production of magnesium by the ferrosilicon thermal process is completed, break the vacuum, take the material, and prepare for the production of the next batch; observe and record the crystallization position of the magnesium vapor in the crystallizer during the previous batch of magnesium production by the ferrosilicon thermal process. When the crystallization position deviates from the large-diameter end face of the crystallizer, adjust the loading amount of the material balls in the reduction tank during the next batch of magnesium production by the ferrosilicon thermal process so that the crystallization position of the magnesium vapor in the crystallizer is flush with the large-diameter end face of the crystallizer.

[0026] During the reduction process of magnesium by the ferrosilicon thermal process, the stacked material balls show a state of loose stacking on the upper part and dense stacking on the lower part due to their own gravity. As a result, the generated magnesium vapor tends to flow from the looser place above the stacked material balls. The gradient condensation component in the temperature and pressure dual-control device provided by the present invention has a first heat-resistant plate in the shape of a bow larger than a semi-circle, with the chord facing upwards, so that the magnesium vapor can flow directly into the component above the material balls, reducing the bending path of the vapor and thus reducing the gas resistance. At the same time, the gradient condensation component is constructed by several parallel heat-resistant plates to form a gradient condensation channel, with a simple structure. The first heat-resistant plate facing the material ball side plays a role in heat resistance, reducing the heat radiation loss at the material ball, increasing the temperature of the material ball at the tank opening, and then improving the reaction rate of the material ball and bringing a production increase effect. The second heat-resistant plate is located between the first and third heat-resistant plates, dividing its internal space into two regions. Among them, the first region (between the first and second heat-resistant plates) has a higher temperature near the high-temperature material ball; while the second region (between the second and third heat-resistant plates) has a lower temperature due to the staggered heat-resistant effect of the first and second heat-resistant plates. Since the saturated vapor pressures of gaseous impurities and magnesium vapor are different and their deposition temperatures are different, there is a low-temperature window, so that the impurities can be deposited as much as possible while the magnesium vapor is not deposited. Accordingly, the present invention places a filter screen in the second low-temperature region with appropriate temperature, so that the impurities can be deposited and intercepted on the filter screen with a larger specific surface area as much as possible. At the same time, since the vapor will surely flow out through the middle through-hole of the third heat-resistant plate, the filter screen is closely attached to the third heat-resistant plate, enabling more vapor to pass through the screen.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. The temperature and pressure dual-control device provided by the present invention includes a hollow frustum-shaped transition cylinder that physically limits the distance between the gradient condensation component and the crystallizer, creating a temperature difference between the two and providing a wider temperature adjustment space. It not only avoids the problem that the magnesium partial pressure near the gradient condensation component increases due to the addition of the gradient condensation component and large gas resistance, being higher than the saturated vapor pressure at the corresponding temperature and depositing on it; but also avoids the problem that the temperature of the crystallizer in contact with it increases due to increasing the temperature to prevent the deposition of magnesium vapor on the gradient condensation component, thus causing the problem of the crystallized magnesium catching fire.

[0029] 2. The temperature and pressure dual-control device provided by the present invention includes a gradient condensation component designed based on the vapor flow path. Without significantly increasing the gas resistance, it can achieve the collision capture of particulate impurities and the precise temperature-controlled deposition of vapor impurities, with excellent impurity removal effects, enabling the purity of primary magnesium to reach Mg9995A or above.

[0030] 3. The temperature and pressure dual-control device provided by the present invention includes a gradient condensation component that not only covers the mouth of the reduction tank, reducing the heat radiation loss inside the reduction tank, but also avoids the direct contact between the cold-end crystallizer and the interceptor to conduct away heat; it can increase the temperature on the side of the charge balls at the mouth of the reduction tank, thereby increasing the reaction rate of these charge balls and having a good yield increase effect.

[0031] 4. The temperature and pressure dual-control device provided by the present invention solves the problems of ignition of crystalline magnesium and difficulty in removing the formed magnesium, is easy to clean, can be reused repeatedly, and also extends the service life of the components. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a structural cross-sectional view of the temperature and pressure dual-control device for silicon thermal reduction of magnesium provided by an embodiment of the present invention;

[0033] Figure 2 is a schematic structural diagram of the gradient condensation component provided by an embodiment of the present invention; among them, (a) represents the structural cross-sectional view of the gradient condensation component; (b) represents the main structural view of the gradient condensation component;

[0034] Figure 3 is the left structural view of the gradient condensation component provided by an embodiment of the present invention; among them, (c) represents the left structural view of the gradient condensation component; (d) represents the left structural view of the second heat insulation plate of the gradient condensation component.

[0035] Figure 4 is the simulation result of the influence of the hollow frustum-shaped transition cylinder on the temperature field provided by an embodiment of the present invention; among them, (a1) represents the traditional straight cylinder-shaped transition cylinder; (b1) represents the hollow frustum-shaped transition cylinder provided by the present invention;

[0036] Figure 5 is the influence result of the gradient condensation component on the temperature field and pressure field provided by an embodiment of the present invention; (a2) represents the influence of the gradient condensation component on the temperature field; (b2) represents the influence of the gradient condensation component and the traditional fire-blocking transition device on the pressure field

[0037] Figure 6 is the purification effect after silicon thermal reduction of magnesium using the temperature and pressure dual-control device for silicon thermal reduction of magnesium provided by an embodiment of the present invention;

[0038] Figure 7 is the yield increase effect after silicon thermal reduction of magnesium using the temperature and pressure dual-control device for silicon thermal reduction of magnesium provided by an embodiment of the present invention;

[0039] Figure 8 The results of the operation after the silicon thermal magnesium smelting production method using the temperature and pressure dual-control device for silicon thermal magnesium smelting provided by the embodiments of the present invention.

[0040] Appendix Figures 1-3 In the following, the list of components represented by each label is as follows:

[0041] 10. Silicon thermal magnesium smelting device;

[0042] 100. Gradient condensation component; 200. Reduction tank; 300. Hollow frustum-shaped temperature adjustment transition cylinder; 400. Cooler; 500. Crystallizer;

[0043] 1001. First heat insulation plate; 1002. Second heat insulation plate; 1003. Third heat insulation plate; 1004. Protection plate; 1005. Gradient condensation channel; 1006. Through hole; 1007. Filter screen; 1008. Limit flange. Specific embodiments

[0044] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other implementation manners obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope protected by the present invention.

[0045] Embodiment

[0046] Based on the appendix Figures 1-3 , this embodiment provides a temperature and pressure dual-control device for silicon thermal magnesium smelting, including a reduction tank 200 and a cooler 400. A hollow frustum-shaped temperature adjustment transition cylinder 300 is arranged between the tank mouth of the reduction tank 200 and the cooler 400. The small-diameter end of the hollow frustum-shaped temperature adjustment transition cylinder 300 is fixedly connected to the end face of the tank mouth of the reduction tank 200, and the large-diameter end of the hollow frustum-shaped temperature adjustment transition cylinder 300 is fixedly connected to the cooler 400; in the prior art, the cooler 400 is a water-cooled cooler;

[0047] A gradient condensation component 100 is arranged inside the tank mouth of the reduction tank 200;

[0048] A crystallizer 500 is arranged inside the cooler 400, and one end of the crystallizer 500 abuts against the inner wall of the hollow frustum-shaped temperature adjustment transition cylinder 300;

[0049] In this embodiment, the reduction tank 200, the temperature adjustment transition cylinder 300, the cooler 400, the gradient condensation assembly 100, and the crystallizer 500 are all coaxially arranged. The outer diameter of the reduction tank 200 is 390 mm, the inner diameter is 310 mm, and the length is 3300 mm; the outer diameter of the cooler 400 is 377 mm, the inner diameter is 349 mm, and the length is 800 mm; the outer diameter of the large diameter end of the hollow frustum-shaped temperature adjustment transition cylinder is 377 mm, the outer diameter of the small diameter end is 353 mm, the wall thickness is 14 mm, and the length is 121 mm.

[0050] In some examples, the distance between one end with a large diameter of the crystallizer 500 and the gradient condensation assembly 100 is 10 - 100 mm.

[0051] In some examples, the gradient condensation assembly 100 includes a first heat insulation plate 1001, a second heat insulation plate 1002, a third heat insulation plate 1003, and a guard plate 1004;

[0052] The first heat insulation plate 1001 is in the shape of an arc greater than a semi-circle with the chord facing upwards; the first heat insulation plate 1001 and the third heat insulation plate 1003 are arranged in parallel, and the guard plate 1004 is connected between the lower end of the first heat insulation plate 1001 and the third heat insulation plate 1003, and the guard plate 1004 and the first heat insulation plate 1001, the third heat insulation plate 1003 enclose a gradient condensation channel 1005; positioning notches are provided at both ends of the guard plate 1004, and the edge of the second heat insulation plate 1002 is snap-fitted with the positioning notches;

[0053] The second heat insulation plate 1002 includes an upper semi-circular plate and a lower semi-drum plate. The lower straight side of the upper semi-circle is integrally connected to the top straight side of the lower semi-drum plate. The radius of the lower semi-drum plate is equal to the arc inner diameter of the guard plate 1004. The radius R2 of the upper semi-circular plate is not less than the radius R1 of the lower semi-circle, so that the upper semi-circular plate can be snap-fitted with the positioning notch. Of course, in order to ensure that the second heat insulation plate 1002 can be placed inside the reduction tank 200, the radius R2 of the upper semi-circular plate is less than or equal to the inner diameter of the tank mouth of the reduction tank 200; preferably, the radius R2 of the upper semi-circular plate is equal to the inner diameter of the tank mouth of the reduction tank 200.

[0054] The second heat insulation plate 1002 and the first heat insulation plate 1001, the third heat insulation plate 1003 are arranged in parallel, and the lower end of the second heat insulation plate 1002 extends into the gradient condensation channel 1005;

[0055] The side surface of the second heat insulation plate 1002 is hermetically connected to both ends of the guard plate 1004, and a gap is provided between the lower end of the second heat insulation plate 1002 and the bottom wall of the gradient condensation channel 1005;

[0056] A through hole 1006 is provided on the third heat insulation plate 1003. The shape of the third heat insulation plate 1003 is circular, and the side of the guard plate 1004 away from the third heat insulation plate 1003 is fixedly connected to the arc edge of the first heat insulation plate 1001.

[0057] In this embodiment, the centers of the first heat insulation plate 1001, the second heat insulation plate 1002, and the third heat insulation plate 1003 are coaxially arranged, and the through hole 1006 is coaxial with the third heat insulation plate 1003.

[0058] In this embodiment, to ensure the stable fixation of the second heat insulation plate 1002 and the guard plate 1004, the widths of the positioning notches at both arc-shaped ends of the guard plate 1004 are the same as the width of the second heat insulation plate 1002, and both positioning notches extend along the arc direction of the guard plate 1004 until they reach the position flush with the horizontal diameter of the guard plate 1004. When the second heat insulation plate 1002 is inserted into the guard plate 1004 through the positioning notch, the arc-shaped edge of the lower half-drum of the second heat insulation plate 1002 abuts against the inner side wall of the guard plate 1004, and a limiting edge that can abut against the bottom wall of the positioning notch is formed between the arc edge of the upper semi-circle and the arc edge of the lower half-drum. Of course, it is easy to understand that the lower half-drum is formed by cutting off a minor arc segment from the semi-circular bottom with the same inner diameter as the arc-shaped guard plate 1004, so that a channel for magnesium vapor to pass through is formed between the lower end of the second heat insulation plate 1002 and the guard plate 1004, and this channel is located below the central axis of the gradient condensation assembly 100. The magnesium vapor generated by the reaction in the reduction tank 200 first enters between the first heat insulation plate 1001 and the second heat insulation plate 1002 from the upper side of the first heat insulation plate 1001, then enters between the second heat insulation plate 1002 and the third heat insulation plate 1003 through the channel on the lower side of the second heat insulation plate 1002, and then is discharged through the through hole 1006.

[0059] In some instances, a limiting flange 1008 for abutting and cooperating with the end face of the tank opening of the reduction tank 200 is radially extended at the edge of the third heat insulation plate 1003. The outer diameter of the limiting flange 1008 is less than or equal to the inner diameter of the small-diameter end of the hollow frustum-shaped temperature-adjusting transition cylinder 300, and the outer diameter of the limiting flange 1008 is greater than the inner diameter of the tank opening of the reduction tank 200. When assembling the gradient condensation assembly 100, the limiting flange 1008 abuts against the end face of the tank opening of the reduction tank 200.

[0060] In this embodiment, the limiting flange 1008 increases the radius of the third heat insulation plate 1003, so that the radius of the third heat insulation plate 1003 is greater than the inner diameter of the tank opening of the reduction tank 200. In this way, the first heat insulation plate 1001, the second heat insulation plate 1002, and the guard plate 1004 can be placed inside the tank opening, and the tank opening limiting flange 1008 of the third heat insulation plate 1003 can abut against the end face of the tank opening, thereby limiting the installation position of the gradient condensation assembly 100 inside the reduction tank 200, and at the same time, stabilizing the temperature of the magnesium vapor discharged through the through hole 1006 through gradient heat insulation.

[0061] In this embodiment, the diameter of the major arc part of the first heat insulation plate 1001 is 286 mm, the distance from the center of the circle to the chord is 83 mm, and the plate thickness is 7 mm; the diameter of the upper semi-circular plate of the second heat insulation plate 1002 is 286 mm, the diameter of the lower semi-drum plate is 268 mm, the linear distance from the center of the circle to the bottom end of the drum plate is 100 mm, and the plate thickness is 6 mm; the diameter of the third heat insulation plate 1003 is 322 mm, and the diameter of the middle through hole 1006 is 115 mm; the arc-shaped outer diameter of the guard plate is 286 mm, and the plate thickness is 8 mm.

[0062] In some examples, a filter screen 1007 is arranged between the third heat insulation plate 1003 and the second heat insulation plate 1002.

[0063] In this embodiment, the filter screen 1007 is a plain woven mesh, with a diameter of 220 mm, a pore diameter of 6 mm, a wire diameter of 2.5 mm, and the material is carbon steel; the filter screen 1007 completely covers the through hole 1006, and the edge of the filter screen 1007 is fixed to the surface of the third heat insulation plate 1003; of course, the filter screen 1007 can be coaxially arranged with the third heat insulation plate 1003.

[0064] This embodiment also provides a method for using the above-mentioned silicon thermal magnesium smelting temperature and pressure dual-control device, and the method includes the following steps:

[0065] (1) Place one end of the reduction tank of the silicon thermal magnesium smelting temperature and pressure dual-control device in the reduction furnace, charge the reduction tank 200 with feed balls containing CaO, MgO, Si and CaF 2 , the filling end position of the feed balls is 0 - 200 mm away from the gradient condensation component, and then the gradient condensation component and the crystallizer are loaded in sequence and sealed;

[0066] (2) Vacuumize the entire silicon thermal magnesium smelting silicon thermal reduction device 10 to <20 Pa, control the wall temperature of the charging area of the reduction tank 200 to rise to 1100 - 1300 °C, and start the silicon thermal method for magnesium smelting production;

[0067] (3) After the silicon thermal method for magnesium smelting production is completed, break the vacuum, take the material, and prepare for the next batch of production; observe and record the crystallization position of the magnesium vapor in the crystallizer during the previous batch of silicon thermal method for magnesium smelting. When the crystallization position deviates from the large-diameter end face of the crystallizer, in the next batch of silicon thermal magnesium smelting production, adjust the charging amount of the feed balls in the reduction tank 200 so that the crystallization position of the magnesium vapor in the crystallizer is flush with the large-diameter end face of the crystallizer.

[0068] According to the silicon thermal magnesium smelting temperature and pressure dual-control device described in this embodiment, the influence of the hollow frustum-shaped transition cylinder on the temperature field was compared by means of simulation, as Figure 4 (a1) shows that in the straight cylinder transition area device of the traditional silicon thermal method, the end face of the gradient condensation component is in contact with the crystallizer, and their temperatures are almost the same; while in the present invention, asFigure 4 As shown in (b1), through the setting of the hollow frustum-shaped transition cylinder, the gradient condensation component is separated from the crystallizer, and there is a temperature difference of nearly 100 °C between the two, providing sufficient temperature adjustment space.

[0069] Since the present invention also provides a gradient condensation component with a simple structure, small gas resistance and capable of constructing a suitable impurity removal temperature, and the rationality of its design is also verified by means of simulation. As Figure 5 shown in (a2), in terms of constructing a suitable impurity removal temperature gradient, it can be seen that for the gradient condensation component provided by the present invention, the temperature between the first and second heat plates is high, about 987 - 815 °C, and the temperature between the second and third heat plates is low, about 864 - 639 °C. This temperature is exactly in the temperature range where magnesium vapor is not easily deposited while impurities with low saturated vapor pressure are easily deposited. Placing a filter with a large specific surface area here will have an excellent impurity removal effect. In terms of the gas resistance of the structure, the present invention selects the structure in Patent CN202111071001.1 as the control group. As Figure 5 shown in (b2), the gas resistance of the structure of the gradient condensation component provided by the present invention is significantly reduced.

[0070] In the effect test for 1 consecutive month in this embodiment, the purity of the produced crude magnesium reaches Mg9995A and above (as Figure 6 ); compared with the control group of the experimental magnesium enterprise in the same period, the output slightly increases (as Figure 7 ); and the production operation time is significantly reduced (as Figure 8 shown), which means that there are almost no common production operation problems such as ignition of crude magnesium and difficulty in removing agglomerated magnesium.

[0071] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "length", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "inner", "outer", "peripheral side", "circumferential direction", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0072] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0073] In the description of this specification, the descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0074] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A temperature and pressure dual-control device for silicon thermal magnesium smelting, characterized in that, it includes a reduction tank (200) and a cooler (400). It is characterized in that a hollow frustum-shaped temperature-adjusting transition cylinder (300) is arranged between the tank mouth of the reduction tank (200) and the cooler (400). The small-diameter end of the hollow frustum-shaped temperature-adjusting transition cylinder (300) is fixedly connected to the end face of the tank mouth of the reduction tank (200), and the large-diameter end of the hollow frustum-shaped temperature-adjusting transition cylinder (300) is fixedly connected to the cooler (400); a gradient condensation assembly (100) is arranged inside the tank mouth of the reduction tank (200); a crystallizer (500) is arranged inside the cooler (400), and one end of the crystallizer (500) abuts against the inner wall of the hollow frustum-shaped temperature-adjusting transition cylinder (300); the distance between the large-diameter end of the crystallizer (500) and the gradient condensation assembly (100) is 10-100 mm; the gradient condensation assembly (100) includes a first heat-resistant plate (1001), a second heat-resistant plate (1002), a third heat-resistant plate (1003) and a guard plate (1004); the first heat-resistant plate (1001) is in the shape of a bow greater than a semi-circle, and the chord faces upward; the first heat-resistant plate (1001) and the third heat-resistant plate (1003) are arranged in parallel, and the guard plate (1004) is connected between the lower end of the first heat-resistant plate (1001) and the third heat-resistant plate (1003), and the guard plate (1004) and the first heat-resistant plate (1001), the third heat-resistant plate (1003) enclose a gradient condensation channel (1005); positioning notches are arranged at both ends of the guard plate (1004), and the edge of the second heat-resistant plate (1002) is clamped and matched with the positioning notches; the second heat-resistant plate (1002) includes an upper semi-circular plate and a lower semi-drum plate. The lower straight edge of the upper semi-circle is integrally connected to the top straight edge of the lower semi-drum plate. The radius of the lower semi-drum plate is equal to the arc inner diameter of the guard plate (1004), and the radius of the upper semi-circular plate is not less than the radius of the lower semi-drum plate; the second heat-resistant plate (1002) and the first heat-resistant plate (1001), the third heat-resistant plate (1003) are arranged in parallel, and the lower end of the second heat-resistant plate (1002) extends into the gradient condensation channel (1005); the side surface of the second heat-resistant plate (1002) is hermetically connected to both ends of the guard plate (1004), and a gap is arranged between the lower end of the second heat-resistant plate (1002) and the bottom wall of the gradient condensation channel (1005); a through hole (1006) is arranged on the third heat-resistant plate (1003). The shape of the third heat-resistant plate (1003) is circular, and the side of the guard plate (1004) away from the third heat-resistant plate (1003) is fixedly connected to the arc edge of the first heat-resistant plate (1001).

2. The temperature and pressure dual-control device for silicon thermal magnesium smelting according to claim 1, characterized in that, A limiting flange (1008) for abutting and cooperating with the end face of the tank opening of the reduction tank (200) is radially extended at the edge of the third heat insulation plate (1003).

3. The silicon thermal magnesium smelting temperature and pressure double control device according to claim 1, characterized in that a filter screen (1007) is arranged between the third heat insulation plate (1003) and the second heat insulation plate (1002).

4. A method for silicon thermal magnesium smelting temperature and pressure double control, characterized in that the silicon thermal magnesium smelting temperature and pressure double control device described in any one of claims 1-3 is used for magnesium smelting; the method comprises the following steps: (1) Place one end of the reduction tank of the silicon thermal magnesium smelting temperature and pressure double control device in a reduction furnace, charge the reduction tank (200) with material balls containing CaO, MgO, Si and CaF2, and the filling end position of the material balls is 0-200 mm away from the gradient condensation assembly. Then, sequentially install the gradient condensation assembly and the crystallizer and seal them; (2) Vacuum the entire silicon thermal magnesium smelting reduction device (10) to <20 Pa, control the wall temperature of the charging area of the reduction tank (200) to rise to 1100-1300 °C, and start the silicon thermal magnesium smelting production; (3) After the silicon thermal magnesium smelting production is completed, break the vacuum, take the material, and prepare for the next batch of production; observe and record the crystallization position of the magnesium vapor in the crystallizer in the previous batch of silicon thermal magnesium smelting. When the crystallization position deviates from the large diameter end face of the crystallizer, in the next batch of silicon thermal magnesium smelting production, adjust the charging amount of the material balls in the reduction tank (200) so that the crystallization position of the magnesium vapor in the crystallizer is flush with the large diameter end face of the crystallizer.

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