External polycrystalline magnesium reduction reaction device and method thereof

Abstract

The invention belongs to the technical field of magnesium smelting, and discloses an external polycrystalline magnesium reduction reaction device and a method thereof.The external polycrystalline magnesium reduction reaction device comprises a vertical tank, a center cylinder is coaxially installed in the vertical tank, a plurality of steam through holes are evenly distributed in the wall of the center cylinder, a transition cylinder with the upper end and the lower end open is installed at the top of the vertical tank, and the lower end of the transition cylinder communicates with a containing chamber; an upper end cover is arranged at the top end of the transition barrel, a plurality of branch pipe barrels are arranged in the circumferential direction of the transition barrel, the branch pipe barrels are communicated with the containing chamber, and magnesium crystallization devices are installed at the tail ends of the branch pipe barrels; the external polycrystal type magnesium reduction reaction device and method have the flexible adjusting capacity and can actively adapt to working condition changes, efficient crystallization of magnesium vapor changes is achieved, and meanwhile the tolerance of the device to production fluctuation is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnesium smelting, and in particular relates to an external polycrystalline magnesium reduction reaction device and a method thereof. Background Art

[0002] Silicon thermal magnesium smelting is a predominant magnesium smelting technology both domestically and internationally. Raw materials undergo a three-step process: calcination, reduction, and refining, producing raw magnesium (crude magnesium). Compared to horizontal tank smelting, this vertical magnesium smelting process has become increasingly popular in recent years due to its advantages, including automatic gravity slag discharge, large loading capacity, and high production efficiency. The primary equipment for vertical magnesium smelting is the vertical tank, typically a long cylindrical structure consisting of three sections: the upper section for condensation and crystallization, the middle section for the main body, or reduction section, and the lower section for slag discharge. These three sections are connected by flanges or / and welding to form a sealed chamber. The condensation and crystallization section, or magnesium crystallizer, is typically housed within the tank. A reduction furnace mounted on the reduction furnace heats the exterior of the vertical tank, while a vacuum pump evacuates the interior. When the temperature in the vertical tank is about 1200℃ and the pressure is usually around 10Pa, a reduction reaction occurs to produce magnesium vapor. The magnesium vapor crystallizes after being cooled in the magnesium crystallizer to obtain solid raw magnesium (crude magnesium). The crude magnesium is then melted, refined and cast into ingots to obtain commercial magnesium.

[0003] Conventional reactors generally utilize a vertical tank and a single crystallizer. The crystallizer is typically fixed at the top of the tank. Upon entering the crystallizer, magnesium vapor is cooled and cooled, resulting in the crystallization of magnesium metal. However, this structure often presents the following problems in actual operation: First, magnesium vapor generation decreases when the feedstock is reduced, production loads are adjusted, or the raw material composition fluctuates. Due to the fixed internal crystallization heat exchange area of ​​existing single crystallizers, the amount of magnesium vapor generated cannot dynamically adapt to changes in the amount of magnesium vapor. This results in magnesium vapor crystallizing on the inner wall of the crystallizer in a thin layer with a loose crystal structure. This phenomenon not only reduces the density of the crystallized magnesium ingot and increases the impurity content, but also makes magnesium removal difficult due to changes in the contact area between the crystallization layer and the wall, resulting in abnormal bonding strength. Second, the fixed position of the crystallizer barrel at the top of the traditional vertical tank places the crystallizer in the upper high-temperature zone within the tank, which is accessible by radiation. This exacerbates process control challenges. When the raw material composition fluctuates or the temperature control parameters shift, magnesium vapor tends to crystallize disorderly between the inner wall of the vertical tank and the crystallizer, forming a bridging crust. This phenomenon directly hinders the normal removal of the crystallizer, forcing production to be interrupted for manual slag removal, seriously disrupting production continuity. Furthermore, during the troubleshooting process, components such as the vertical tank and center tube are exposed to a non-vacuum environment for a long time. The high-temperature tank body and internal components (such as the center tube) experience severe oxidative corrosion in the presence of air, significantly shortening the equipment's service life and increasing production costs.

[0004] Therefore, it is urgent to develop a crystallizer structure solution with flexible adjustment capabilities and the ability to actively adapt to changes in working conditions to achieve efficient crystallization of magnesium vapor changes. Summary of the Invention

[0005] In order to solve the technical problems existing in the prior art, the present invention proposes an external polycrystalline magnesium reduction reaction device and method thereof; the technical solution adopted to achieve the above purpose is:

[0006] An external multi-crystallization magnesium reduction reaction device and method thereof include a vertical tank, a lower end cover provided at the bottom of the vertical tank, a central tube coaxially installed in the vertical tank, a plurality of steam holes evenly distributed on the wall of the central tube, a receiving chamber for storing magnesium raw material balls between the central tube and the vertical tank, a transition tube with open upper and lower ends installed on the top of the vertical tank, the lower end of the transition tube connected to the receiving chamber, an upper end cover provided on the top of the transition tube, and a plurality of branch tubes provided around the circumference of the transition tube, the branch tubes connected to the receiving chamber, and a magnesium crystallization device installed at the end of each branch tube;

[0007] The magnesium crystallization device includes a cooling water jacket coaxially installed at the end of a branch tube, a crystallization end cover is installed at the end of the cooling water jacket, a crystallization tube is fixed in the cooling water jacket, a water outlet pipe and a water inlet pipe are provided on the cooling water jacket, and a vacuum pipe connected to the branch tube is provided on the cooling water jacket.

[0008] Preferably, a closed chamber extending toward the transition tube is provided at the bottom of the upper end cover, and a heat-insulating material is encapsulated in the closed chamber.

[0009] Preferably, the bottom of the closed chamber is a downward convex arc surface, and the downward convex arc surface is used to divert and guide the magnesium vapor into each branch tube.

[0010] Preferably, an annular pressing cylinder for pressing the crystallization cylinder is provided at the bottom of the crystallization end cover, a hollow is provided on the wall of the annular pressing cylinder, and a support for supporting the crystallization cylinder is provided in the cooling water jacket.

[0011] Preferably, control valves are installed on both the water outlet pipe and the water inlet pipe, and a vacuum pump is connected to the vacuum pipe.

[0012] Preferably, an annular support seat for supporting the central tube is provided at the bottom of the vertical tank, and when the central tube rises, the magnesium reduction slag leaks out from the middle of the annular support seat.

[0013] Preferably, a vacuum-breaking air inlet pipeline is provided on the transition tube, a control valve is installed on the vacuum-breaking air inlet pipeline, and the vacuum-breaking air inlet pipeline is connected to an inert gas source.

[0014] A magnesium reduction reaction method using the external polycrystalline magnesium reduction reaction device as described above is characterized by comprising the following steps:

[0015] Step A: While the reduction furnace continues to heat the vertical tank, a certain amount of magnesium raw material pellets are taken into the holding chamber according to production needs, a crystallization cylinder and a crystallization end cover are installed at the end of each branch tube, and the lower end cover, upper end cover and each sealed crystallization end cover of the vertical tank are fixed and sealed;

[0016] Step B: Open and control the circulating water volume of one of the cooling water jackets, open the vacuum pipe control valve corresponding to the cooling water jacket to vacuum the vertical tank, and close the vacuum pipe control valves corresponding to all other cooling water jackets. At this time, the powder in the tank and the trace amount of magnesium / metal vapor in the early stage enter one of the crystallization tubes to start crystallization;

[0017] Step C: When the absolute pressure in the vertical tank reaches about 1000-5000 Pa and the temperature of the magnesium raw material pellets in the vertical tank rises to about 1080-1190° C., a large amount of magnesium vapor is reduced from the magnesium raw material pellets. At this time, the circulating water volume of the cooling water jacket opened in step B is reduced and controlled, and the vacuum pipe corresponding to the cooling water jacket is closed; the circulating water volume of all other cooling water jackets is opened and controlled, and the vacuum pipe control valves corresponding to all other cooling water jackets are opened, so that a large amount of magnesium vapor enters other crystallization tubes to start crystallization;

[0018] Step D: After magnesium reduction is completed, close the vacuum pipe control valves of each cooling water jacket, open the control valve of the vacuum-breaking air inlet pipe to break the vacuum until the pressure reaches normal, and finally discharge magnesium and slag.

[0019] Preferably, in step C, the number of magnesium crystallization devices that are turned on is appropriately controlled according to the change in the amount of magnesium vapor generated.

[0020] Preferably, in step D, the magnesium removal step comprises:

[0021] Step D1: Open each crystallization end cover, take out the crystallization cylinder to discharge magnesium, and simultaneously reset each crystallization end cover;

[0022] Step D2: With the upper end cover restored, open the lower end cover and lift the center tube from the bottom to discharge slag;

[0023] Step D3: After the slag is discharged, the center tube falls back to its original position by its own weight.

[0024] The beneficial effects of the present invention are as follows: (1) by arranging a plurality of magnesium crystallization devices distributed circumferentially at the end of the vertical tank, refined control of magnesium vapor crystallization is achieved.

[0025] (2) When the amount of magnesium vapor generated fluctuates, the number of magnesium crystallization devices working can be appropriately adjusted to ensure the density and quality of the magnesium ingots crystallized in the crystallization cylinder.

[0026] (3) Before the magnesium reduction reaction, the vertical tank is vacuumed, and in the initial stage of the reduction reaction, the air flow only passes through one of the crystallization tubes, avoiding contamination of other crystallization tubes and laying the foundation for the crystallization of high-purity magnesium crystals in other crystallization tubes.

[0027] (4) Separation and control of the initial, middle and final stages of magnesium reduction are achieved, so that crude magnesium crystals with impurities in the early stage and high-purity magnesium crystals can be separated in the reduction stage in the vertical tank. High-purity magnesium crystals are exempted from refining, shortening the process and reducing the number of steps.

[0028] (5) When the upper end cover of the vertical tank is reset, the central tube is lifted from the bottom to discharge the slag, which can effectively avoid the "chimney effect" and improve the production environment.

[0029] (6) The present invention realizes an external multi-crystal magnesium reduction reaction device and method thereof with flexible adjustment capability and the ability to actively adapt to changes in working conditions, so as to achieve efficient crystallization of magnesium vapor changes and improve the tolerance of the device to production fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic structural diagram of the present invention in Example 1;

[0031] Figure 2 This is a schematic structural diagram of the present invention in Example 2;

[0032] Figure 3 for Figure 2 Middle section view along AA direction. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the accompanying drawings.

[0034] Example 1:

[0035] like Figure 1 As shown, an external multi-crystallization magnesium reduction reaction device includes a vertical tank A2, a lower end cover A5 is provided at the bottom of the vertical tank A2, a central tube A3 is coaxially installed in the vertical tank A2, a plurality of steam holes are evenly distributed on the wall of the central tube A3, a holding chamber for placing magnesium raw material balls A1 is provided between the central tube A3 and the vertical tank A2, a transition tube B3 with upper and lower open ends is installed on the top of the vertical tank A2, the lower end of the transition tube B3 is connected to the holding chamber, an upper end cover B2 is provided on the top of the transition tube B3, and a plurality of branch tubes B1 are provided circumferentially around the transition tube B2, the branch tubes B1 are connected to the holding chamber, and a magnesium crystallization device C is installed at the end of each branch tube B1; as shown Figure 2 and Figure 3 As shown, it is a schematic diagram of 4 branch tubes B1 and 4 magnesium crystallization devices C.

[0036] The magnesium crystallization device C includes a cooling water jacket C2 coaxially installed at the end of a branch tube B1, a crystallization end cover C3 is installed at the end of the cooling water jacket C2, a crystallization tube C1 is fixed in the cooling water jacket C2, a water outlet pipe C7 and a water inlet pipe C4 are provided on the cooling water jacket C2, a vacuum pipe C10 connected to the branch tube B3 is provided on the cooling water jacket C2, control valves C6, C5, C9 are installed on the water outlet pipe C7, the water inlet pipe C4 and the vacuum pipe C10, and a vacuum pump C8 is connected to the vacuum pipe C10.

[0037] An annular support base A4 is located at the bottom of the vertical tank A2, supporting the central cylinder A3. As the central cylinder A3 rises, magnesium-reduced slag leaks out from the center of the support base A4. A vacuum-breaking air intake pipe (not shown) is installed in the transition cylinder B3. A control valve is installed on the pipe, which is connected to an inert gas source such as nitrogen.

[0038] Example 2:

[0039] like Figure 2 As shown, on the basis of Example 1, in order to prevent the magnesium vapor from gathering at the top of the transition tube B3 and cooling down when it rises into the transition tube B3, thereby affecting the occurrence of magnesium vapor crystallization, a closed chamber extending to the transition tube B3 is provided at the bottom of the upper end cover B2, and an insulation material B5 is encapsulated in the closed chamber. The high-temperature insulation material B5 maintains a higher temperature environment in the transition tube B3, reducing the crystallization of magnesium vapor when it cools down here.

[0040] On the other hand, the bottom of the closed chamber is a downward convex arc surface B4. When the magnesium vapor rises, it quickly enters each branch tube B1 under the diversion and guidance effect of the downward convex arc surface B4, thereby reducing the accumulation of magnesium vapor here.

[0041] Example 3:

[0042] like Figure 2 and Figure 3 As shown, an annular pressing cylinder C14 for pressing the crystallization cylinder C1 is provided at the bottom of the crystallization end cover C3, and a hollow is provided on the wall of the annular pressing cylinder C14. A support C15 for supporting the crystallization cylinder C1 is provided in the cooling water jacket C2, thereby further ensuring that the crystallization cylinder C1 is tightly pressed on the support seat, thereby preventing the magnesium vapor in the branch tube B1 from entering the outside of the crystallization cylinder C1.

[0043] like Figure 3 As shown, the length of the branch tube B1 is shortened at the same time to further reduce the distance of the magnesium vapor before entering the crystallizer C1.

[0044] Example 4:

[0045] A magnesium reduction reaction method using the external polycrystalline magnesium reduction reaction device as described above comprises the following steps:

[0046] Step A: If Figure 1 or Figure 2 As shown, while the reduction furnace A6 continues to heat the vertical tank A2, a certain amount of magnesium raw material balls A1 are taken into the holding chamber according to production needs, and the crystallization cylinder C1 and the crystallization end cover C3 are installed at the end of each branch tube B1. The cooling water jacket C2 is installed in advance and does not need to be removed normally. The lower end cover A5, the upper end cover B2 and each sealed crystallization end cover C3 of the vertical tank A2 are fixed and sealed;

[0047] Step B: Open and control the circulating water volume of one of the cooling water jackets C2, such as Figure 1 As shown, the vacuum pipe C10 corresponding to the cooling water jacket C2 is opened to control the valve C9 to evacuate the vertical tank A2, and the vacuum pipe control valves corresponding to all other cooling water jackets are closed. At this time, the powder in the tank and the trace amount of magnesium / metal vapor in the early stage only enter the crystallization cylinder C1 to start crystallization, producing a small amount of coarse crystalline magnesium C11;

[0048] Step C: When the absolute pressure in the vertical tank A2 reaches about 1000-5000Pa and the temperature of the magnesium raw material balls A1 in the vertical tank A2 rises to about 1080-1190°C, a large amount of magnesium vapor is reduced from the magnesium raw material balls A1 and rises. Under the diversion and guidance action of the downward convex arc surface B4, it quickly enters each branch tube B1, thereby reducing the accumulation of magnesium vapor here. At the same time, under the action of the high-temperature insulation material B5, the magnesium vapor is reduced from cooling and crystallizing here, thereby improving the quality of magnesium crystallization and the amount of magnesium output.

[0049] At this time, the circulating water volume of the cooling water jacket C2 opened in step B is reduced and controlled, and the control valve C9 of the vacuum pipe C10 corresponding to the cooling water jacket C2 is closed, the purpose of which is to stop the crystallization of magnesium in the crystallization tube C1; the circulating water volume of all other cooling water jackets is opened and controlled, and the vacuum pipe control valves corresponding to all other cooling water jackets are opened, so that a large amount of magnesium vapor enters the other crystallization tubes to start crystallization, producing a large amount of fine crystalline magnesium C13;

[0050] Step D: After magnesium reduction is completed, the vacuum pipe control valves of each cooling water jacket C2 are closed, and the control valves of the vacuum-breaking air inlet pipes are opened to break the vacuum until the pressure reaches normal, and finally magnesium and slag are discharged.

[0051] Further, if Figure 2 and Figure 3 As shown, in step C, according to the change of magnesium vapor generation amount, the number of magnesium crystallization devices opened is appropriately controlled. In this embodiment, there are 4 branch tubes B1 and 4 magnesium crystallization devices C. Figure 2 The crystallization cylinder C1 on the middle left is used to produce a small amount of crude crystalline magnesium C11 in the initial stage of magnesium reduction reaction. Figure 2 The crystallization tube on the right and Figure 3 The crystallization tube on the left is used to produce a large amount of fine crystal magnesium C13 and C16 in the middle and late stages of magnesium reduction reaction. Figure 3 The crystallization cylinder on the right is shut down when the amount of magnesium vapor is low.

[0052] Further, in step D, the magnesium removal step includes:

[0053] Step D1: Open each crystallization end cover C3, take out the crystallization cylinder C1 to remove magnesium, and simultaneously reset each crystallization end cover C3;

[0054] Step D2: With the upper end cover B2 restored, open the lower end cover A5 and lift the center tube A3 from the bottom to discharge slag;

[0055] Step D3: After the slag is discharged, the central tube A3 falls back to its original position by its own weight.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An external multi-crystal magnesium reduction reaction device, comprising a vertical tank, characterized in that: A lower end cover is provided at the bottom of the vertical tank, a central tube is coaxially installed in the vertical tank, a plurality of steam holes are evenly distributed on the wall of the central tube, a holding chamber for placing magnesium raw material balls is provided between the central tube and the vertical tank, a transition tube with upper and lower ends open is provided on the top of the vertical tank, the interior of the transition tube is connected to the holding chamber, an upper end cover is provided on the top of the transition tube, and a plurality of branch tubes are provided around the circumference of the transition tube, the branch tubes are connected to the holding chamber, and a magnesium crystallization device is installed at the end of each branch tube; The magnesium crystallization device includes a cooling water jacket coaxially installed at the end of a branch tube, a crystallization end cover is installed at the end of the cooling water jacket, a crystallization tube is fixed in the cooling water jacket, a water outlet pipe and a water inlet pipe are provided on the cooling water jacket, and a vacuum pipe connected to the branch tube is provided on the cooling water jacket.

2. The external polycrystalline magnesium reduction reaction device according to claim 1, characterized in that: A closed chamber extending toward the transition tube is provided at the bottom of the upper end cover, and a heat-insulating material is packaged in the closed chamber.

3. The external multi-crystalline magnesium reduction reaction device and method according to claim 2, characterized in that: The bottom of the closed chamber is a downward convex arc surface, which is used to divert the magnesium vapor into each branch tube.

4. The external polycrystalline magnesium reduction reaction device according to any one of claims 1 to 3, characterized in that: An annular pressing cylinder for pressing the crystallization cylinder is provided at the bottom of the crystallization end cover, a hollow is provided on the wall of the annular pressing cylinder, and a support for supporting the crystallization cylinder is provided in the cooling water jacket.

5. The external multi-crystal magnesium reduction reaction device according to claim 4, characterized in that: Control valves are installed on the water outlet pipe and the water inlet pipe, and a vacuum pump is connected to the vacuum pipe.

6. The external multi-crystalline magnesium reduction reaction device according to any one of claims 1 to 3, characterized in that: An annular support seat for supporting the central tube is provided at the bottom of the vertical tank. When the central tube rises, the magnesium reduction slag leaks out from the middle of the annular support seat.

7. The external multi-crystal magnesium reduction reaction device according to any one of claims 1 to 3, characterized in that: A vacuum-breaking air inlet pipeline is provided on the transition tube, a control valve is installed on the vacuum-breaking air inlet pipeline, and the vacuum-breaking air inlet pipeline is connected to an inert gas source.

8. A magnesium reduction reaction method using the external polycrystalline magnesium reduction reaction device as described above, characterized in that: The steps include: Step A: While the reduction furnace continues to heat the vertical tank, a certain amount of magnesium raw material pellets are taken into the holding chamber according to production needs, a crystallization cylinder and a crystallization end cover are installed at the end of each branch tube, and the lower end cover, upper end cover and each sealed crystallization end cover of the vertical tank are fixed and sealed; Step B: Open and control the circulating water volume of one of the cooling water jackets, open the vacuum pipe control valve corresponding to the cooling water jacket to vacuum the vertical tank, and close the vacuum pipe control valves corresponding to all other cooling water jackets. At this time, the powder in the tank and the trace amount of magnesium metal vapor in the early stage enter one of the crystallization tubes to start crystallization; Step C: When the absolute pressure in the vertical tank reaches about 1000-5000 Pa and the temperature of the magnesium raw material pellets in the vertical tank rises to about 1080-1190° C., a large amount of magnesium vapor is reduced from the magnesium raw material pellets. At this time, the circulating water volume of the cooling water jacket opened in step B is reduced and controlled, and the vacuum pipe corresponding to the cooling water jacket is closed; the circulating water volume of all other cooling water jackets is opened and controlled, and the vacuum pipe control valves corresponding to all other cooling water jackets are opened, so that a large amount of magnesium vapor enters other crystallization tubes to start crystallization; Step D: After magnesium reduction is completed, close the vacuum pipe control valves of each cooling water jacket, open the control valve of the vacuum-breaking air inlet pipe to break the vacuum until the pressure reaches normal, and finally discharge magnesium and slag.

9. The magnesium reduction reaction method according to claim 8, characterized in that In step C, the number of magnesium crystallization devices that are turned on is appropriately controlled according to the change in the amount of magnesium vapor generated.

10. The magnesium reduction reaction method according to claim 8 or 9, characterized in that: In step D, the magnesium removal step comprises: Step D1: Open each crystallization end cover, take out the crystallization cylinder to discharge magnesium, and simultaneously reset each crystallization end cover; Step D2: With the upper end cover restored, open the lower end cover and lift the center tube from the bottom to discharge slag; Step D3: After the slag is discharged, the center tube falls back to its original position by its own weight.

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