Crystallization method and crystallization device for crystallized magnesium

Abstract

The invention relates to the technical field of magnesium crystallization, in particular to a crystallization method and a crystallization device for crystallized magnesium. The crystallization method takes magnesium steam containing impurities as a raw material, and comprises the following steps: vibrating the magnesium steam; wherein the vibration frequency is larger than or equal to 50 Hz; the magnesium steam is crystallized under the vibration condition, crystal nucleuses of the magnesium steam grow in an accelerated mode, the impurities are separated, and crystallized magnesium is obtained. According to the crystallization method, vibration with the frequency of 50 Hz and above is used, the crystallization process of magnesium steam is optimized from the two dimensions of molecular dynamics and crystallization boundary layer control, and the crystal nucleus forming speed and crystallization efficiency of magnesium and the purity of a crystallized magnesium product can be improved. The unit energy consumption of the crystallization method can be controlled to be 8.0 kWh / kg or below, the impurity adhesion rate is controlled to be 40% or below, and a crystallized magnesium product with the purity being 99.90% or above can be finally obtained through the crystallization method.

Description

Technical Field

[0001] This application relates to the technical field of magnesium crystallization, and particularly relates to a crystallization method and a crystallization device for crystalline magnesium. Background Art

[0002] At present, the main method for producing magnesium is the reduction method. The main principle of the reduction method is to reduce magnesium salts or magnesium vapor with different valence states into metallic magnesium in a reduction tank, and precipitate the metallic magnesium in a crystalline form through crystallization. The preparation of magnesium crystals by the reduction method generally needs to be carried out in a reduction tank. At present, the reduction tank is divided into a horizontal reduction tank and a vertical reduction tank. However, the horizontal reduction tank has certain defects compared with the vertical reduction tank. Therefore, at present, the production of magnesium crystals mainly uses the vertical reduction tank.

[0003] However, in the process of producing magnesium crystals by the vertical reduction tank, there are problems of low magnesium crystal efficiency and low purity of the magnesium crystal product, which are difficult to meet the actual production and use requirements of magnesium crystals. Summary of the Invention

[0004] This application provides a crystallization method and a crystallization device for crystalline magnesium to solve the following technical problems: how to simultaneously improve the efficiency and purity of magnesium crystallization.

[0005] In the first aspect, an embodiment of this application provides a crystallization method for crystalline magnesium. The crystallization method uses magnesium vapor containing impurities as a raw material, and the crystallization method includes:

[0006] Vibrating the magnesium vapor; wherein, the frequency of the vibration ≥ 50 Hz;

[0007] Under the vibration condition, crystallize the magnesium vapor to accelerate the growth of crystal nuclei of the magnesium vapor and separate the impurities to obtain crystalline magnesium.

[0008] Optionally, the frequency of the vibration is 50 Hz to 200 Hz.

[0009] Optionally, the amplitude of the vibration is 0.5 mm to 2 mm.

[0010] Optionally, the temperature of the crystallization is 350 °C to 450 °C, and the crystallization period of the crystallization is 3 h to 5 h.

[0011] Optionally, the temperature of the magnesium vapor ≥ 1150 °C.

[0012] In the second aspect, an embodiment of this application provides a crystallization device for crystalline magnesium. The crystallization device is adapted to the crystallization method in the first aspect, and the crystallization device includes:

[0013] The main body of a vertical reduction tank;

[0014] The crystallization part includes a crystallizer and a vibration assembly. The crystallizer is arranged at the upper part of the vertical reduction tank body. One end of the vibration assembly is connected to the vertical reduction tank body, and the other end of the vibration assembly is connected to the crystallizer. Regular vibration of the crystallizer is achieved through the vibration assembly. A cooling space is formed among the vibration assembly, the crystallizer, and the vertical reduction tank body.

[0015] The transfer channel includes a conical central pipe and a magnesium vapor inlet. The conical central pipe is arranged at the lower part of the vertical reduction tank body. The magnesium vapor inlet is arranged at the bottom inlet of the conical central pipe.

[0016] Optionally, the vibration assembly includes an electromagnetic coil, a magnet, and a vibration conduction rod. One end of the vibration conduction rod is connected to the vertical reduction tank body, and the other end of the vibration conduction rod is connected to the crystallizer. The electromagnetic coil and the magnet are arranged at the connection between the vibration conduction rod and the vertical reduction tank body. The magnet is arranged outside the electromagnetic coil, and the magnetic poles of the magnet are arranged alternately.

[0017] Optionally, the crystallization part further includes a negative pressure suction port, which is arranged at the inlet of the cooling space.

[0018] Optionally, the transfer channel further includes: pipe holes and a purification filler layer. The purification filler layer is formed between the conical central pipe and the vertical reduction tank body. The pipe holes are arranged on the pipe wall of the conical central pipe to enable the connection between the magnesium vapor and the purification filler layer.

[0019] Optionally, the crystallization part further includes a sieve, which is arranged between the crystallizer and the conical central pipe. The aperture of the sieve is 10μm - 50μm.

[0020] The above technical solution provided by the embodiments of the present application has the following advantages compared with the prior art:

[0021] The embodiments of the present application provide a crystallization method for crystalline magnesium. This crystallization method uses vibrations with a frequency of 50Hz or above, which can effectively increase the molecular kinetic energy of magnesium vapor, increase the intensity of molecular motion of magnesium vapor, so as to increase the collision frequency between magnesium molecules. Magnesium molecules with high-frequency collisions can overcome the repulsive force between magnesium molecules, thereby increasing the nucleation rate of crystalline magnesium during the crystallization process. In addition, vibration can break the boundary layer of the crystalline magnesium formed during the crystallization process, enabling magnesium vapor to deposit on the crystal surface of the crystalline magnesium, increasing the nucleation rate of crystalline magnesium, and thus improving the efficiency of magnesium crystallization. Furthermore, vibration can increase the kinetic energy of impurities in magnesium vapor, and impurities with high kinetic energy are difficult to fixedly adhere to the crystal surface of crystalline magnesium and form free impurities, which can reduce the amount of impurities adhering to the crystal surface of crystalline magnesium, thereby improving the purity of crystalline magnesium. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with the present application and, together with the specification, are used to explain the principles of the present application.

[0023] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following briefly introduces the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 Schematic flow diagram of a crystallization method for crystalline magnesium provided by an embodiment of the present application;

[0025] Figure 2 Logical structure diagram of a crystallization device for crystalline magnesium provided by an embodiment of the present application;

[0026] Figure 3 Actual structure diagram of a crystallization device for crystalline magnesium provided by an embodiment of the present application;

[0027] Among them, 1 - vertical reduction tank body, 2 - crystallizer, 3 - vibration assembly, 301 - magnetic coil, 302 - magnet, 303 - vibration conduction rod, 4 - conical central tube, 5 - magnesium vapor inlet, 6 - negative pressure suction port, 7 - pipe hole, 8 - purification packing layer, 9 - screen. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following clearly and completely describes the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0029] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and individual values within that range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range; in addition, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0030] In this document, terms such as "including" mean "including but not limited to". Relative terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. "And / or" describes the associated relationship of associated objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "multiple" means two or more; "at least one kind", "at least one of the following items (pieces)" or similar expressions refer to any combination of these items, including any combination of single item (piece) or plural items (pieces); for example, "at least one of a, b, or c", or, "at least one of a, b, and c" can both represent: a, b, c, a - b (that is, a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively. The "parts representation method" such as parts by weight, parts by mass, etc. represents the proportional relationship between each component. In the proportional relationships involved in this document, the parameters that need to be described by proportion should be understood as the antecedents of the proportion formula in the order of description, and the proportional numbers should be understood as the consequents of the proportion formula. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one by one with the proportional numbers in the proportion formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0031] Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment, etc. used in this document can be obtained through market purchases or can be prepared by existing methods.

[0032] It should be noted that the current horizontal reduction tank has problems such as small single-furnace output, inability to continuously produce, and low production automation level. Modifying the traditional horizontal reduction tank into a vertical reduction tank, in the vertical reduction tank, the reduction slag can be discharged from the lower part by gravity. Then, by configuring appropriate mechanical equipment and combining modern control technology, the mechanical operation of the furnace charge and the crude magnesium product in the vertical reduction tank and the automatic discharge of the reduction slag can be realized, which realizes the automated, mechanized, and user-friendly production in the magnesium smelting industry.

[0033] Although the vertical reduction tank has improvements in continuous production and automatic slag discharge compared with the traditional horizontal reduction tank, there are still the following technical defects: (1) The crystallization efficiency of the vertical reduction tank is low, and the collection time of the magnesium product is long. Since the position of the crystallizer in the vertical reduction tank is in the upper part of the vertical reduction tank, during the stage of collecting magnesium vapor, the magnesium vapor needs to overcome its own gravity to enter the upper crystallizer, which results in the collection rate of the magnesium product in the vertical reduction tank being lower than that of the traditional horizontal reduction tank. This leads to a higher mass ratio of the raw material input to the magnesium product output during the magnesium smelting process in the vertical reduction tank, and a long production time and high production energy consumption during the magnesium smelting process. (2) The problem of adherent magnesium smelting residue. During the magnesium smelting process in the vertical reduction tank, the collection of magnesium vapor is not clean, indirectly resulting in the material residue in the vertical reduction tank being easily adhered to the inner wall of the vertical reduction tank, affecting the discharge effect of the magnesium smelting residue. (3) The low purity of the crystalline magnesium product. During the crystallization process in the vertical reduction tank, impurities such as magnesium oxide (MgO) and silicate are easily attached to the crystal surface of the crystalline magnesium as the magnesium vapor rises, which makes the purity of the crystalline magnesium obtained in the magnesium smelting process of the traditional vertical reduction tank within 98.5% to 99.0%.

[0034] Figure 1 Exemplarily shown is a schematic flow diagram of a crystallization method for crystalline magnesium provided by an embodiment of the present application;

[0035] As Figure 1 shown, an embodiment of the present application provides a crystallization method for crystalline magnesium. The crystallization method uses magnesium vapor containing impurities as a raw material, and the crystallization method includes:

[0036] S1. Vibrate the magnesium vapor; wherein, the frequency of the vibration ≥ 50 Hz;

[0037] S2. Crystallize the magnesium vapor under the vibration condition, accelerate the growth of the crystal nuclei of the magnesium vapor and separate the impurities to obtain crystalline magnesium.

[0038] It should be noted that generally, magnesium vapor is used as the raw material for crystallization based on the characteristic of its low impurity content. In addition, the process of magnesium changing from the gas phase to the solid phase can be achieved through controllable temperature regulation. Therefore, preparing magnesium crystals with magnesium vapor as the raw material has the advantage of strong controllability.

[0039] It should be noted that this vibration can use a continuous vibration mode or an intermittent vibration mode, and the specific vibration mode is determined by the requirements of the actual magnesium crystallization process.

[0040] It should be noted that the embodiment of the present application provides a crystallization method for crystalline magnesium. This crystallization method uses vibrations with a frequency of 50 Hz or above to optimize the crystallization process of magnesium vapor from two dimensions: molecular dynamics and crystallization boundary layer control, which can improve the nucleation rate, crystallization efficiency, and purity of the crystalline magnesium product. The core principle of this crystallization method is as follows:

[0041] 1. Influence of high-frequency vibration on the molecular dynamics of magnesium vapor:

[0042] (1) Increase molecular kinetic energy and collision frequency:

[0043] 1) Enhancement of molecular kinetic energy: High-frequency vibration transfers energy through mechanical waves, enabling magnesium vapor molecules (Mg) to obtain additional kinetic energy and move faster.

[0044] 2) Increase in collision frequency: According to the kinetic theory of gases, the molecular collision frequency is positively correlated with the molecular velocity. The vibration energy can make magnesium molecules collide more frequently to overcome the van der Waals repulsive force between magnesium molecules and promote the formation of magnesium crystal nuclei.

[0045] 3) Enhancement of nucleation rate: Based on the classical nucleation theory, the nucleation rate of crystal nuclei has an exponential relationship with the molecular collision frequency, and high-frequency vibration will reduce the energy barrier and accelerate the speed of magnesium crystallization.

[0046] (2) Inhibit impurity adsorption:

[0047] 1) Increase in impurity kinetic energy: The vibration energy is transferred to impurity molecules, making it difficult for them to stably adsorb on the surface of magnesium crystals.

[0048] 2) Inhibition of selective adsorption: High-kinetic-energy impurities are difficult to move synchronously with magnesium crystals as the vibration progresses due to inertia. Based on a similar centrifugal separation effect, these high-kinetic-energy impurities will be "thrown away" from the surface of magnesium crystals, while magnesium molecules are more likely to deposit directionally due to their smaller mass.

[0049] 2. Regulation of the crystallization boundary layer by vibration:

[0050] (1) Break the diffusion boundary layer:

[0051] 1) Boundary layer theory: In static crystallization, a concentration gradient (diffusion boundary layer) of magnesium vapor will form on the surface of magnesium crystals, hindering the deposition of new magnesium molecules.

[0052] (2) Vibration shearing effect: High-frequency vibration generates periodic shear forces at the solid-gas interface, disrupting the stability of the diffusion boundary layer and enabling magnesium vapor molecules to directly contact the surface of the magnesium crystal, thereby increasing the deposition rate of magnesium molecules.

[0053] (2) Promote surface renewal of magnesium crystals:

[0054] (1) Micro-region flow effect: Vibration induces the formation of micron-scale turbulence on the surface of magnesium crystals, rearranging the already deposited magnesium atoms and reducing the lattice defects of magnesium crystals.

[0055] (2) Dendrite fragmentation: Vibration can break the loosely bound dendrite structure, prevent the formation of large grains, and improve the uniformity of magnesium crystallization.

[0056] In some alternative embodiments, the frequency of the vibration is 50 Hz to 200 Hz.

[0057] In these embodiments, the frequency of vibration directly affects the molecular dynamics of magnesium vapor molecules and the regulation of the magnesium crystallization boundary layer. Controlling the vibration frequency within the range of 50 Hz to 200 Hz can increase the vibration frequency, and high-frequency vibration can enhance the molecular dynamics of magnesium vapor and improve the crystallization efficiency of magnesium vapor. Additionally, high-frequency vibration can also break the crystallization-blocking tendency of the magnesium crystallization boundary layer, improve the surface crystallization effect of magnesium crystals, and promote the crystallization efficiency of magnesium vapor. Moreover, high-frequency vibration can increase the momentum of impurities in magnesium vapor, transforming the impurities from a fixed state to a free state, enabling the separation of impurities from magnesium crystallization, and thus improving the purity of magnesium crystallization.

[0058] The frequency of this vibration can be 50 Hz, 60 Hz, 70 Hz, 80 Hz, 90 Hz, 100 Hz, 110 Hz, 120 Hz, 130 Hz, 140 Hz, 150 Hz, 160 Hz, 170 Hz, 180 Hz, 190 Hz, or 200 Hz.

[0059] In some alternative embodiments, the amplitude of the vibration is 0.5 mm to 2 mm.

[0060] In these embodiments, the amplitude of vibration directly affects the energy transfer of vibration. Controlling the amplitude within the range of 0.5 mm to 2 mm keeps the vibration amplitude at a relatively low level, and a lower vibration amplitude can avoid a large amount of loss of vibration energy, thereby increasing the energy of magnesium vapor molecules during the vibration stage. High-energy magnesium vapor molecules can enhance the molecular dynamics of magnesium vapor and break the magnesium crystallization boundary layer, thus effectively improving the crystallization efficiency and purity of magnesium.

[0061] The amplitude of the vibration can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, or 2.0 mm.

[0062] It should be noted that the amplitude of the vibration is directly related to the energy distribution of the vibration. A large amplitude of the vibration indicates that the energy distribution of the vibration is concentrated in the displacement change of the vibration, which will affect the frequency change of the vibration, thereby affecting the energy distribution of the vibration.

[0063] In some alternative embodiments, the temperature of the crystallization is 350°C to 450°C, and the crystallization period of the crystallization is 3 h to 5 h.

[0064] In these embodiments, the crystallization parameters of 350°C to 450°C and 3 h to 5 h can provide sufficient temperature and crystallization time for the crystallization process. Under the influence of this crystallization temperature and crystallization period, the magnesium vapor is fully crystallized to increase the output of crystalline magnesium.

[0065] The temperature of the crystallization can be 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, or 450°C.

[0066] The crystallization period of the crystallization can be 3 h, 3.5 h, 4.0 h, 4.5 h, or 5.0 h.

[0067] In some alternative embodiments, the temperature of the magnesium vapor ≥ 1150°C.

[0068] In these embodiments, the temperature of the magnesium vapor above 1150°C can maintain the magnesium in a gaseous state, enabling the subsequent crystallization process to proceed smoothly.

[0069] Figure 2 Exemplarily shown is the logical structure diagram of a crystallization device for crystalline magnesium provided by an embodiment of the present application;

[0070] Figure 3 Exemplarily shown is the actual structure diagram of a crystallization device for crystalline magnesium provided by an embodiment of the present application;

[0071] Based on a general inventive concept, as Figure 2 and Figure 3 shown, an embodiment of the present application provides a crystallization device for crystalline magnesium. The crystallization device is adapted to the crystallization method described in the first aspect. The crystallization device includes:

[0072] Vertical reduction tank body 1;

[0073] The crystallization section includes a crystallizer 2 and a vibration assembly 3. The crystallizer 2 is arranged at the upper part of the vertical reduction tank body 1. One end of the vibration assembly 3 is connected to the vertical reduction tank body 1, and the other end of the vibration assembly 3 is connected to the crystallizer 2. Regular vibration of the crystallizer 2 is achieved through the vibration assembly 3. A cooling space is formed among the vibration assembly 3, the crystallizer 2, and the vertical reduction tank body 1.

[0074] The transfer channel includes a conical central pipe 4 and a magnesium vapor inlet 5. The conical central pipe 4 is arranged at the lower part of the vertical reduction tank body 1. The magnesium vapor inlet 5 is arranged at the bottom inlet of the conical central pipe 4.

[0075] This crystallization device is realized based on the above crystallization method. The specific steps of this crystallization method can refer to the above embodiments. Since this crystallization device adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated one by one here.

[0076] It should be noted that a vibration assembly 3 is introduced into the crystallization section. Through the vibration of the vibration assembly 3, the crystallizer 2 generates regular and high-frequency vibration. The high-frequency vibration can improve the molecular dynamics of magnesium vapor in the crystallizer 2 and the surface crystallization effect of magnesium crystals, thereby improving the crystallization efficiency of magnesium vapor. In addition, the high-frequency vibration can also increase the momentum of impurities in magnesium vapor, converting the impurities from a fixed state to a free state, and realizing the separation of impurities from magnesium crystallization.

[0077] It should be noted that the inner wall of the vertical reduction tank body 1 can use high-temperature-resistant stainless steel material to ensure the smooth crystallization of magnesium vapor.

[0078] It should be noted that an electric heating device can be arranged in the conical central pipe 4 to maintain the temperature of magnesium vapor at 1150 °C or above during the movement stage in the conical central pipe 4.

[0079] It should be noted that the material of the screen 9 can use porous ceramic material, and the aperture of the screen 9 can gradually change, so that some impurities such as magnesium oxide and silicate in magnesium vapor are removed through the filtering action of the screen 9, improving the purity of the crystalline magnesium formed by magnesium vapor on the crystallizer 2.

[0080] In some alternative embodiments, the vibration assembly 3 includes an electromagnetic coil 301, a magnet 302, and a vibration conduction rod 303. One end of the vibration conduction rod 303 is connected to the vertical reduction tank body 1, and the other end of the vibration conduction rod 303 is connected to the crystallizer 2. The electromagnetic coil 301 and the magnet 302 are provided at the connection between the vibration conduction rod 303 and the vertical reduction tank body 1. The magnet 302 is disposed outside the electromagnetic coil 301, and the magnetic poles of the magnet 302 are arranged alternately.

[0081] In these embodiments, the vibration assembly 3 including the electromagnetic coil 301, the magnet 302, and the vibration conduction rod 303 is used. The electromagnetic coil 301 and the vertical reduction tank body 1 can be connected through the vibration conduction rod 303. After the electromagnetic coil 301 is energized, an alternating magnetic field can be generated. Through the interaction with the magnet 302, a repulsive or attractive phenomenon can occur. By arranging the magnetic poles of the magnet 302 alternately, when the electromagnetic coil 301 repels or attracts the magnet 302, the electromagnetic coil 301 will drive the vibration conduction rod 303 to perform a longitudinal reciprocating motion, thereby realizing continuous or periodic vibration of the crystallizer 2 through the vibration conduction rod 303.

[0082] It should be noted that the magnet 302 can be a permanent magnet 302. Specifically, the magnet 302 can be an annular neodymium iron boron magnet 302. The magnet 302 is disposed outside the electromagnetic coil 301, and the magnetic poles of the magnet 302 are arranged alternately. Under the action of different magnetic poles, the electromagnetic coil 301 will drive the vibration conduction rod 303 to form a longitudinal reciprocating motion.

[0083] It should be noted that the electromagnetic coil 301 can be an annular coil, and the diameter of the electromagnetic coil 301 matches the upper cover of the vertical reduction tank. The material of the electromagnetic coil 301 can be copper wire, and high-temperature resistant insulating glue is filled between the gaps of each layer of the electromagnetic coil 301.

[0084] It should be noted that the material of the vibration conduction rod 303 can be a nickel-based alloy. The shape of the vibration conduction rod 303 can be cylindrical, and the diameter of the cylindrical vibration conduction rod 303 is greater than or equal to 50 mm. The surface of the vibration conduction rod 303 can be coated with a silicon carbide coating.

[0085] In some alternative embodiments, the crystallization part further includes a negative pressure suction port 6, and the negative pressure suction port 6 is disposed at the feed port of the cooling space.

[0086] In these embodiments, a negative pressure suction port 6 is introduced into the crystallization part. Through the negative pressure suction port 6, the pressure in the cooling space can be reduced, so that the cooling space is in a state close to a vacuum environment, which can improve the heat exchange capacity between the cooling space and the crystallizer 2 to maintain the crystallization temperature of the crystallizer 2 within the range of 350°C to 450°C.

[0087] It should be noted that the negative pressure suction port 6 can make the pressure in the cooling space within 5 Pa to maintain the crystallizer 2 in an environment close to a vacuum during the crystallization stage.

[0088] It should be noted that when the cooling liquid needs to be poured into the cooling space, the water flow rate of the cooling liquid can be 10 L / min to 20 L / min.

[0089] In some alternative embodiments, the transfer channel further includes: a pipe hole 7 and a purification filler layer 8. A purification filler layer 8 is formed between the conical central pipe 4 and the vertical reduction tank body 1. The pipe hole 7 is provided on the pipe wall of the conical central pipe 4 to realize the connection between the magnesium vapor and the purification filler layer 8.

[0090] In these embodiments, a purification filler layer 8 and a pipe hole 7 are introduced into the transfer channel. Through the pipe hole 7, the magnesium vapor can be introduced into the purification filler layer 8. Through the purification of the purification filler layer 8, impurities such as magnesium oxide and silicate in the magnesium vapor can be initially removed.

[0091] It should be noted that the purification filler layer 8 can use a mixture of calcium chloride and sodium chloride as the filling material.

[0092] In some alternative embodiments, the crystallization part further includes a sieve mesh 9. The sieve mesh 9 is provided between the crystallizer 2 and the conical central pipe 4, and the aperture of the sieve mesh 9 is 10 μm to 50 μm.

[0093] In these embodiments, the sieve mesh 9 with an aperture of 10 μm to 50 μm can fully separate impurities such as magnesium oxide and silicate precipitated during the crystallization of magnesium vapor, preventing these impurities from adhering to the surface of magnesium crystals to improve the purity of crystalline magnesium.

[0094] The aperture of the sieve mesh 9 can gradually change from 10 μm to 50 μm. Among them, along the diffusion direction of the magnesium vapor, the sieve mesh 9 with an aperture of 50 μm is arranged upstream of the sieve mesh 9 with an aperture of 10 μm.

[0095] It should be noted that with the vibration of the crystallizer 2, the sieve mesh 9 may also vibrate, causing impurities such as magnesium oxide and silicate attached to the sieve mesh 9 to fall off, so that reduction slag can be collected at the lower port of the conical central pipe 4.

[0096] It should be noted that during actual use, the conical central tube 4 can be lifted by a crane and placed inside the vertical reduction tank body 1, and then the filter screen, the crystallizer 2, and the upper cover plate of the vertical reduction tank are hoisted in sequence to assemble the crystallization device. At this time, the temperature of the heating crystallization device is raised to 1150°C; then magnesium vapor is introduced into the conical central tube 4 through the magnesium vapor inlet 5 of the vertical reduction tank body 1, and the impurities in the magnesium vapor are preliminarily purified through the purification packing layer 8 around the conical central tube 4, and then the impurities in the magnesium vapor are further removed through the filter screen; at the same time, the negative pressure suction port 6 is opened to make the pressure in the cooling space below 5 Pa. After the magnesium vapor enters the crystallizer 2, the negative pressure suction port 6 is used as the coolant inlet to maintain the temperature of the crystallizer 2 within the range of 350°C to 450°C; at this time, the electromagnetic coil 301 of the vibration assembly 3 is energized to generate an alternating magnetic field. Under the action of the magnet 302 and the alternating magnetic field, the vibration conduction rod 303 starts to work, making the surface of the crystallizer 2 vibrate, thereby completing the crystallization process; after the crystallization is completed, the upper cover plate of the vertical reduction tank is lifted by a crane, and then the crystallizer 2 is lifted. At the same time, the vibration assembly 3 is removed, and the magnesium crystal product in the crystallizer 2 is collected, that is, the crystallization process is completed. The following further elaborates on this application in combination with specific embodiments. The experimental methods without specific conditions indicated in the following embodiments are usually determined in accordance with national standards / industry standards; if there are no corresponding national standards / industry standards, they are carried out in accordance with general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0097] Example 1

[0098] As Figure 1 shown, a crystallization method for crystalline magnesium uses magnesium vapor containing impurities as raw material, including:

[0099] S1. Vibrate the magnesium vapor;

[0100] S2. Crystallize the magnesium vapor under vibration conditions to accelerate the growth of crystal nuclei of the magnesium vapor and separate impurities to obtain crystalline magnesium.

[0101] The vibration uses a continuous vibration mode.

[0102] The vibration frequency is 80 Hz.

[0103] The vibration amplitude is 2 mm.

[0104] The crystallization temperature is 350°C to 450°C, and the crystallization cycle of crystallization is 5 h.

[0105] The temperature of the magnesium vapor is 1150°C.

[0106] As Figure 2 and Figure 3 shown, a crystallization device for crystalline magnesium includes:

[0107] Vertical reduction tank body 1;

[0108] Crystallization part, including a crystallizer 2 and a vibration assembly 3. The crystallizer 2 is arranged at the upper part of the vertical reduction tank body 1; one end of the vibration assembly 3 is connected to the vertical reduction tank body 1, and the other end of the vibration assembly 3 is connected to the crystallizer 2. Regular vibration of the crystallizer 2 is realized through the vibration assembly 3; a cooling space is formed among the vibration assembly 3, the crystallizer 2 and the vertical reduction tank body 1;

[0109] Transfer channel, including a conical central tube 4 and a magnesium vapor inlet 5. The conical central tube 4 is arranged at the lower part of the vertical reduction tank body 1; the magnesium vapor inlet 5 is arranged at the bottom inlet of the conical central tube 4.

[0110] The vibration assembly 3 includes an electromagnetic coil 301, a magnet 302 and a vibration conduction rod 303. One end of the vibration conduction rod 303 is connected to the vertical reduction tank body 1, and the other end of the vibration conduction rod 303 is connected to the crystallizer 2; an electromagnetic coil 301 and a magnet 302 are arranged at the connection of the vibration conduction rod 303 and the vertical reduction tank body 1. The magnet 302 is arranged outside the electromagnetic coil 301, and the magnetic poles of the magnet 302 are arranged alternately. The current of the electromagnetic coil 301 is 5A.

[0111] The crystallization part further includes a negative pressure suction port 6, and the negative pressure suction port 6 is arranged at the inlet of the cooling space.

[0112] The transfer channel further includes: a pipe hole 7 and a purification filler layer 8. A purification filler layer 8 is formed between the conical central tube 4 and the vertical reduction tank body 1, and the pipe hole 7 is arranged on the pipe wall of the conical central tube 4 to realize the communication between the magnesium vapor and the purification filler layer 8.

[0113] Example 2

[0114] Compared with Example 1, the differences in this example are as follows, and the rest of the technical solutions are the same:

[0115] The vibration frequency is 120Hz.

[0116] The vibration amplitude is 1mm.

[0117] The crystallization cycle is 4h.

[0118] The current of the electromagnetic coil 301 is 8A.

[0119] Example 3

[0120] Compared with Example 1, the differences in this example are as follows, and the rest of the technical solutions are the same:

[0121] The vibration frequency is 120Hz.

[0122] The vibration amplitude is 1.5mm.

[0123] The crystallization period of the crystal is 4 h.

[0124] The crystallization section further includes a sieve 9 disposed between the crystallizer 2 and the conical central tube 4, and the aperture of the sieve 9 is 10 μm to 50 μm.

[0125] The current of the electromagnetic coil 301 is 8 A.

[0126] Example 4

[0127] Compared with Example 1, the differences in this example are as follows, and the rest of the technical solutions are the same:

[0128] The vibration adopts an intermittent pulse vibration mode, and the intermittent time is 100 ms.

[0129] The frequency of the vibration is 80 Hz.

[0130] The amplitude of the vibration is 0.5 mm.

[0131] The crystallization period of the crystal is 4 h.

[0132] Comparative Example 1

[0133] Compared with Example 1, the differences in this example are as follows, and the rest of the technical solutions are the same:

[0134] Vibration is not used; that is, the vibration assembly is not used.

[0135] Comparative Example 2

[0136] Compared with Example 1, the differences in this example are as follows, and the rest of the technical solutions are the same:

[0137] The frequency of the vibration is 40 Hz.

[0138] Comparative Example 3

[0139] Compared with Example 1, the differences in this example are as follows, and the rest of the technical solutions are the same:

[0140] The frequency of the vibration is 300 Hz.

[0141] Comparative Example 4

[0142] Compared with Example 1, the differences in this example are as follows, and the rest of the technical solutions are the same:

[0143] The amplitude of the vibration is 0.2 mm.

[0144] Comparative Example 5

[0145] Compared with Example 1, the differences in this example are as follows, and the rest of the technical solutions are the same:

[0146] The amplitude of the vibration is 4 mm.

[0147] Relevant experimental and effect data:

[0148] The unit energy consumption, impurity adhesion rate during the magnesium crystallization process, and the purity of the final crystalline magnesium were respectively statistically analyzed for each example and comparative example, and the results are shown in Table 1.

[0149] Table 1 Parameter situation table of the magnesium crystallization process for each example and comparative example

[0150]

[0151] As can be seen from Table 1, compared with Examples 1 to 4, Comparative Example 1 uses a traditional vertical reduction tank, which has the defects of high energy consumption, high impurity adhesion rate, and relatively low purity of crystalline magnesium. In addition, the crystallization period of Comparative Example 1 is more than 5h, generally 16h.

[0152] In addition, compared with Example 1, Comparative Examples 2 and 4 respectively use a relatively low vibration frequency and a relatively low vibration amplitude, resulting in relatively low vibration energy, which is difficult to meet the crystallization requirements of magnesium vapor, affecting the purity of the final crystalline magnesium and having a relatively high impurity adhesion rate.

[0153] In addition, compared with Example 1, Comparative Examples 3 and 5 respectively use a relatively high vibration frequency and a relatively high vibration amplitude, resulting in relatively high vibration energy, which affects the safe operation of the crystallizer, making it difficult to obtain a large amount of crystalline products on the surface of the final crystallizer. Even though the parameters of the crystalline magnesium product finally obtained in Comparative Example 5 are similar to those of the crystalline magnesium product in the example, the excessive vibration amplitude causes a large amount of crystalline magnesium products to directly fall off and be difficult to be collected by the crystallizer, and the vibration assembly 3 is easily damaged and requires frequent maintenance.

[0154] In summary, a crystallization method for crystalline magnesium provided by an embodiment of the present application uses vibration with a frequency of 50 Hz or above to optimize the crystallization process of magnesium vapor from two dimensions of molecular dynamics and crystallization boundary layer control, which can improve the crystal nucleus formation speed, crystallization efficiency, and purity of the crystalline magnesium product. The unit energy consumption of this crystallization method can be controlled below 8.0 kWh / kg, the impurity adhesion rate is controlled below 40%, and the crystallization method can finally obtain a crystalline magnesium product with a purity of 99.90% or above.

[0155] In addition, a crystallization device for crystalline magnesium provided by an embodiment of the present application can realize the crystallization of magnesium vapor and the automatic discharge of reduction slag. Therefore, through this crystallization device, the problems of high manual dependence and serious impurity adhesion in the magnesium reduction process of the traditional process can be solved, making this crystallization device applicable to industrial continuous production.

[0156] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown in the present application, but rather to the broadest scope consistent with the principles and novel features claimed in the present application.

Claims

1. A crystallization method for crystalline magnesium, wherein the crystallization method uses magnesium vapor containing impurities as a raw material, and the crystallization method includes: Vibrating the magnesium vapor; wherein the frequency of the vibration is ≥ 50 Hz; Crystallizing the magnesium vapor under the vibration condition to accelerate the growth of crystal nuclei of the magnesium vapor and separate the impurities, thereby obtaining crystalline magnesium.

2. The crystallization method according to claim 1, wherein The frequency of the vibration is 50 Hz to 200 Hz.

3. The crystallization method according to claim 1, characterized in that, The amplitude of the vibration is 0.5 mm to 2 mm.

4. The crystallization method according to claim 1, wherein The temperature of the crystallization is 350 °C to 450 °C, and the crystallization period of the crystallization is 3 h to 5 h.

5. The crystallization method according to claim 1, characterized in that, The temperature of the magnesium vapor is ≥ 1150 °C.

6. A crystallization device for crystalline magnesium, wherein the crystallization device is adapted to the crystallization method according to any one of claims 1 to 5, and the crystallization device includes: A vertical reduction tank body; A crystallization part, including a crystallizer and a vibration assembly. The crystallizer is arranged at the upper part of the vertical reduction tank body; one end of the vibration assembly is connected to the vertical reduction tank body, and the other end of the vibration assembly is connected to the crystallizer, and regular vibration of the crystallizer is realized through the vibration assembly; a cooling space is formed among the vibration assembly, the crystallizer and the vertical reduction tank body; A transfer channel, including a conical central pipe and a magnesium vapor inlet. The conical central pipe is arranged at the lower part of the vertical reduction tank body; the magnesium vapor inlet is arranged at the bottom inlet of the conical central pipe.

7. The crystallization device according to claim 6, characterized in that, The vibration assembly includes an electromagnetic coil, a magnet and a vibration conduction rod. One end of the vibration conduction rod is connected to the vertical reduction tank body, and the other end of the vibration conduction rod is connected to the crystallizer; the electromagnetic coil and the magnet are arranged at the connection part of the vibration conduction rod and the vertical reduction tank body, the magnet is arranged outside the electromagnetic coil, and the magnetic poles of the magnet are arranged alternately.

8. The crystallization device according to claim 6, characterized in that, The crystallization part further includes a negative pressure suction port, and the negative pressure suction port is arranged at the inlet of the cooling space.

9. The crystallization device according to claim 6, characterized in that, The transfer channel further includes: pipe holes and a purification filler layer. The purification filler layer is formed between the conical central pipe and the vertical reduction tank body, and the pipe holes are arranged on the pipe wall of the conical central pipe to realize the communication between the magnesium vapor and the purification filler layer.

10. The crystallization device according to claim 6, characterized in that, The crystallization part further includes a screen, and the screen is arranged between the crystallizer and the conical central pipe, and the aperture of the screen is 10 μm to 50 μm.

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