A magnesium refining crystallizer with main and auxiliary crystallization phases and a crystallization method thereof

Abstract

The application belongs to the technical field of magnesium smelting equipment, and discloses a main and auxiliary crystallization phase auxiliary magnesium smelting crystallizer and a crystallization method thereof, which comprises a cylinder body with open upper and lower ends, one or more external branch cylinders are arranged on the cylinder body, the branch cylinders are communicated with the cylinder body, a main crystallization device is arranged on the upper end of the cylinder body, and an auxiliary crystallization device is arranged at the end of the branch cylinder; the fine control of magnesium vapor crystallization is realized through the mutual cooperation of the main crystallization device and the auxiliary crystallization device, the vertical tank is vacuumized before the magnesium reduction reaction, and in the initial stage of the reduction reaction, the airflow only passes through the auxiliary crystallization cylinder of the auxiliary crystallization device, so that the pollution of the main crystallization cylinder is avoided, and the prerequisite for crystallizing high-purity magnesium crystals in the main crystallization cylinder is provided.

Description

Technical Field

[0001] This invention belongs to the technical field of magnesium smelting equipment, and specifically relates to a magnesium crystallizer with primary and secondary crystallization processes and its crystallization method. Background Technology

[0002] The silicothermic process for magnesium smelting, a mainstream magnesium smelting technology, mainly includes three core steps: calcination, reduction, and refining, ultimately producing crude magnesium. With technological advancements, the vertical magnesium smelting process has gradually replaced the traditional horizontal reef process due to its significant advantages, becoming the main direction of technological development in the industry. The core improvement of this process lies in its unique vertical reef structure design and supporting process system.

[0003] The core equipment of the vertical magnesium smelting process is the vertical tank, which adopts a segmented structural design, consisting of three parts: an upper condensation and crystallization section, a middle vertical tank reduction reaction section, and a lower slag discharge section. The sections are connected by flanges or welding to achieve an airtight seal, forming a complete sealed reaction chamber. The condensation and crystallization section integrates a magnesium crystallizer as its core functional component, while the outer wall of the reduction reaction section is equipped with a dedicated reduction furnace heating system. The interior of the tank is maintained under negative pressure by a vacuum pump unit.

[0004] During the process, when the magnesium raw material in the vertical tank undergoes a reduction reaction to generate magnesium vapor, this vapor rises to the condensation and crystallization section under the influence of a temperature gradient. After directional cooling, it forms crude magnesium. The magnesium vapor contains small amounts of reactive metallic impurities, such as sodium and potassium. In the initial stage of the reduction reaction, these impurities are mixed with the crude magnesium. Due to their extremely reactive chemical properties, sodium and potassium are easily oxidized in air and react violently with water, releasing hydrogen gas and a large amount of heat. The generated hydrogen gas can be ignited. When the crude magnesium is removed from the vertical tank, the even more reactive potassium and sodium ignite rapidly upon contact with air. If this ignition is not promptly extinguished with a covering agent, it will further ignite the crude magnesium (especially the less densely crystallized crude magnesium), resulting in both magnesium loss and environmental pollution. Furthermore, the magnesium vapor containing a significant amount of metallic impurities in the initial stage of the reduction reaction, as it passes through the magnesium crystallizer, will continue to contaminate the crystalline magnesium, increasing the impurity content and significantly affecting the purity of the magnesium crystals. Summary of the Invention

[0005] The purpose of this invention is to address the technical problems existing in the prior art by proposing a magnesium crystallizer and its crystallization method with primary and secondary crystallization complementing each other; the technical solution adopted to achieve the above objective is: A magnesium crystallizer with primary and secondary crystallization functions includes a cylindrical body with open top and bottom ends, one or more external branch cylinders on the cylindrical body, the branch cylinders being connected to the cylindrical body, a primary crystallization device being installed at the upper end of the cylindrical body, and a secondary crystallization device being installed at the end of the branch cylinders. The main crystallization device includes a main cooling water jacket coaxially mounted on the upper end of the cylinder body, a main crystallization end cap installed at the end of the main cooling water jacket, a main crystallization cylinder fixed inside the main cooling water jacket, a main water outlet pipe and a main water inlet pipe provided on the main cooling water jacket, and a main vacuum pipe connected to the cylinder body on the main cooling water jacket. The secondary crystallization device includes a secondary cooling water jacket coaxially installed at the end of the branch cylinder, a secondary crystallization end cap installed at the end of the secondary cooling water jacket, a secondary crystallization cylinder fixed inside the secondary cooling water jacket, a secondary water outlet pipe and a secondary water inlet pipe provided on the secondary cooling water jacket, and a secondary vacuum pipe connected to the cylinder body provided on the secondary cooling water jacket. Preferably, the length and inner diameter of the main crystallizer are greater than the length and inner diameter of the secondary crystallizer, and the thermal radiation area between the main crystallizer and the main cooling water jacket is greater than the thermal radiation area between the secondary crystallizer and the secondary cooling water jacket.

[0006] Preferably, an annular pressure cylinder for pressing the secondary crystallizer is provided at the bottom of the secondary crystallizer end cap, the annular pressure cylinder wall is provided with a perforation, and a support for supporting the secondary crystallizer is provided inside the secondary cooling water jacket.

[0007] Preferably, a vacuum-breaking air intake pipe is provided on the cylinder body, a control valve is installed on the vacuum-breaking air intake pipe, and the vacuum-breaking air intake pipe is connected to an inert gas source.

[0008] A magnesium crystallization method using a magnesium crystallizer with primary and secondary crystallizers as described above includes the following steps: Step A: Seal and install the magnesium crystallizer on the top of the magnesium reduction vertical tank, and install the main crystallization cylinder and the auxiliary crystallization cylinder accordingly. Seal each port through the main crystallization end cap and the auxiliary crystallization end cap.

[0009] Step B: Turn on and control the circulation water volume of one of the auxiliary cooling water jackets, open the auxiliary vacuum pipe control valve to evacuate the vertical tank, and close the main vacuum pipe control valve. At this time, the powder and trace amounts of magnesium metal vapor in the tank enter the auxiliary crystallizer to begin crystallization. Step C: When the absolute pressure inside the vertical tank reaches about 1000-5000 Pa and the temperature of the magnesium raw material balls inside the vertical tank rises to about 1080-1190℃, a large amount of magnesium vapor is reduced from the magnesium raw material balls. At this time, reduce the circulation water flow of the auxiliary cooling water jacket and close the auxiliary vacuum pipe; turn on the circulation water flow of the main cooling water jacket and open the control valve of the main vacuum pipe. A large amount of magnesium vapor enters the main crystallizing cylinder to begin crystallization. Step D: After magnesium reduction is complete, close all control valves of the main vacuum pipeline and the auxiliary vacuum pipeline, open the control valve of the vacuum breaking gas inlet pipeline to break the vacuum until atmospheric pressure is reached, and open the main crystallization end cap and the auxiliary crystallization end cap to discharge magnesium and slag.

[0010] Preferably, the cylinder body is provided with three external branch cylinders, and a secondary crystallization device is installed at the end of each branch cylinder. In step C, the number of secondary magnesium crystallization devices operating is appropriately controlled according to the changes in the amount of magnesium vapor generated.

[0011] The beneficial effects of this invention are: (1) Through the cooperation of the main crystallization device and the secondary crystallization device, the fine control of magnesium vapor crystallization is achieved.

[0012] (2) Before the magnesium reduction reaction, the vertical tank is evacuated and in the early stage of the reduction reaction, the gas flow only passes through the secondary crystallization tube of the secondary crystallization device, which avoids contamination of the main crystallization tube and provides a prerequisite for the crystallization of high-purity magnesium crystals in the main crystallization tube.

[0013] (3) Separation control of the initial, middle and later stages of magnesium reduction was achieved, so that the crude magnesium crystals with impurities and the high-purity magnesium crystals in the early stage could be separated in the reduction stage in the vertical tank. The high-purity magnesium crystals were exempted from refining, shortening the process and reducing the number of steps.

[0014] (4) It ensures the purity of the magnesium crystals in the main crystallizer during the later stage of the reduction reaction; it also avoids the loss of crude magnesium caused by potassium and sodium igniting it, and improves the production environment. Through reasonable temperature control, vacuum control and their combination, metal impurities such as potassium and sodium crystallize in the secondary crystallizer. The secondary crystallizer is small and easy to extinguish. At the same time, even if the fire is not extinguished in time, the crude magnesium that was crystallized in the early stage is of poor quality and is lost. Attached Figure Description

[0015] Figure 1 This is one of the structural schematic diagrams of the present invention; Figure 2 This is a schematic diagram of the crystallization process of the present invention; Figure 3 This is one of the structural schematic diagrams of the invention. Detailed Implementation

[0016] The present invention will now be further described with reference to the accompanying drawings. Specific Implementation

[0017] like Figure 1 As shown, a magnesium crystallizer with primary and secondary crystallization functions includes a cylindrical body 1 with open top and bottom ends, an external branch cylinder 3 on the cylindrical body 1, the branch cylinder 3 being connected to the cylindrical body 1, a primary crystallization device A being installed at the upper end of the cylindrical body 1, and a secondary crystallization device B being installed at the end of the branch cylinder 3. The main crystallization device A includes a main cooling water jacket A3 coaxially mounted on the upper end of the cylinder body 1, a main crystallization end cap A7 installed at the end of the main cooling water jacket A3, a main crystallization cylinder A2 fixed inside the main cooling water jacket A3, a main water outlet pipe A8 and a main water inlet pipe A10 provided on the main cooling water jacket A3, and a main vacuum pipe A6 connected to the inside of the cylinder body 1 provided on the main cooling water jacket A3. The secondary crystallization device B includes a secondary cooling water jacket B11 coaxially installed at the end of the branch cylinder 3, a secondary crystallization end cap B8 installed at the end of the secondary cooling water jacket B11, a secondary crystallization cylinder B10 fixed inside the secondary cooling water jacket B11, a secondary water outlet pipe B4 and a secondary water inlet pipe B7 provided on the secondary cooling water jacket B11, and a secondary vacuum pipe B1 connected to the inside of the cylinder body 1 on the secondary cooling water jacket B11. Control valves A9 and A11 are installed on the main outlet pipe A8 and the main inlet pipe A10, respectively. Control valve A5 is installed on the main vacuum pipe A6. Vacuum pump A4 is connected to the end of the main vacuum pipe A6. Control valves B5 and B6 are installed on the auxiliary outlet pipe B4 and the auxiliary inlet pipe B7, respectively. Control valve B2 is installed on the auxiliary vacuum pipe B1. Vacuum pump B3 is connected to the end of the auxiliary vacuum pipe B1.

[0018] The length and inner diameter of the main crystallization cylinder A2 are greater than those of the secondary crystallization cylinder B10. The thermal radiation area between the main crystallization cylinder A2 and the main cooling water jacket A3 is greater than that between the secondary crystallization cylinder B10 and the secondary cooling water jacket B11. The crystallization area of ​​the main crystallization cylinder A2 is 5-10 times that of the secondary crystallization cylinder B10.

[0019] A vacuum-breaking air intake pipe 2 is provided on the cylinder body 1, a control valve is installed on the vacuum-breaking air intake pipe 2, and the vacuum-breaking air intake pipe 2 is connected to an inert gas source. To ensure this, an annular pressure cylinder B13 is provided at the bottom of the sub-crystallization end cap B8 to press the sub-crystallization cylinder B10 tightly. The wall of the annular pressure cylinder B13 has a perforation, and a support B9 is provided inside the sub-cooling water jacket B11 to support the sub-crystallization cylinder B10. This further ensures that the sub-crystallization end cap B8 is tightly pressed onto the support, thereby preventing magnesium vapor from entering the outside of the sub-crystallization end cap B8 from the cylinder body 1.

[0020] The results of the composition analysis of the main crystallizer and the secondary crystallizer are as follows: Main crystallizer Laboratory results (unit: %) 99.708 0.137 0.042 0.046 0.012 0.006 0.003 0.046 Secondary crystallizer Laboratory results (unit: %) 95.621 0.224 0.113 0.098 0.055 0.011 0.009 3.869 Specific Implementation

[0021] like Figure 3As shown, based on specific embodiment 1, two or three external branch cylinders 3 can be provided around the main body 1, and a secondary crystallization device B is installed at the end of each branch cylinder 3. Specific Implementation

[0022] like Figure 2 As shown, a magnesium crystallization method using a magnesium crystallizer with primary and secondary crystallizers as described above includes the following steps: Step A: Seal and install the magnesium crystallizer on the top of the magnesium reduction vertical tank 6, and install the main crystallization cylinder A2 and the auxiliary crystallization cylinder B10 accordingly. Seal each port through the main crystallization end cap A7 and the auxiliary crystallization end cap B8.

[0023] Step B: While the reduction furnace 7 continues to heat the vertical tank 6, a certain amount of magnesium raw material balls 4 are taken according to production needs and loaded into the containment chamber between the vertical tank 6 and the central cylinder 5. Ventilation holes are evenly distributed on the wall of the central cylinder 5. At this time, the circulation water of one of the auxiliary cooling water jackets B11 is turned on and controlled. The auxiliary vacuum pipe B1 control valve B2 is turned on to evacuate the vertical tank 6. The main vacuum pipe A6 control valve A5 is turned off. At this time, the powder in the vertical tank 6 and the trace amount of magnesium metal vapor from the previous stage enter the auxiliary crystallization cylinder B10 to begin crystallization and form coarse magnesium crystals B12. Step C: When the absolute pressure inside the vertical tank 6 reaches about 1000-5000 Pa and the temperature of the magnesium raw material ball 4 inside the vertical tank 6 rises to about 1080-1190℃, a large amount of magnesium vapor is reduced from the magnesium raw material ball 4. At this time, reduce the circulation water flow of the auxiliary cooling water jacket B11 and close the control valve B2 of the auxiliary vacuum pipe B1; open the circulation water flow of the main cooling water jacket A3 and open the control valve A5 of the main vacuum pipe A6. A large amount of magnesium vapor enters the main crystallizing cylinder A2 and begins to crystallize to form pure magnesium crystals A1. Step D: After magnesium reduction is completed, close all control valves A5 and B2 of the main vacuum pipeline A6 and the auxiliary vacuum pipeline B1, open the control valve of the vacuum breaking inlet pipeline 2 to break the vacuum until atmospheric pressure is reached, and open the main crystallization end cap A7 and the auxiliary crystallization end cap B8 to discharge magnesium and slag. Specific Implementation

[0024] Based on specific implementation 3, three external branch cylinders 3 are provided on the cylinder body 1, and a secondary crystallization device B is installed at the end of each branch cylinder 3. In step C, the number of secondary magnesium crystallization devices B working is appropriately controlled according to the change in magnesium vapor generation.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A magnesium crystallizer with primary and secondary crystallization processes, characterized in that, It includes a cylindrical body with open top and bottom ends, one or more external branch cylinders on the cylindrical body, the branch cylinders being connected to the cylindrical body, a main crystallization device being installed at the upper end of the cylindrical body, and a secondary crystallization device being installed at the end of the branch cylinders. The main crystallization device includes a main cooling water jacket coaxially mounted on the upper end of the cylinder body, a main crystallization end cap installed at the end of the main cooling water jacket, a main crystallization cylinder fixed inside the main cooling water jacket, a main water outlet pipe and a main water inlet pipe provided on the main cooling water jacket, and a main vacuum pipe connected to the cylinder body on the main cooling water jacket. The secondary crystallization device includes a secondary cooling water jacket coaxially installed at the end of the branch cylinder, a secondary crystallization end cap installed at the end of the secondary cooling water jacket, a secondary crystallization cylinder fixed inside the secondary cooling water jacket, a secondary water outlet pipe and a secondary water inlet pipe provided on the secondary cooling water jacket, and a secondary vacuum pipe connected to the cylinder body provided on the secondary cooling water jacket. The length and inner diameter of the main crystallization cylinder are greater than the length and inner diameter of the secondary crystallization cylinder, and the thermal radiation area between the main crystallization cylinder and the main cooling water jacket is greater than the thermal radiation area between the secondary crystallization cylinder and the secondary cooling water jacket. An annular pressure cylinder for pressing the secondary crystallizer is provided at the bottom of the secondary crystallizer end cap. The annular pressure cylinder wall has a hollowed-out design. A support for supporting the secondary crystallizer is provided inside the secondary cooling water jacket.

2. The magnesium crystallizer with primary and secondary crystallization as described in claim 1, characterized in that, The cylinder body is provided with a vacuum-breaking air intake pipe, a control valve is installed on the vacuum-breaking air intake pipe, and the vacuum-breaking air intake pipe is connected to an inert gas source.

3. A method for magnesium crystallization using a magnesium crystallizer with primary and secondary crystallization as described in claim 1 or 2, characterized in that, Includes the following steps: Step A: Seal and install the magnesium crystallizer on the top of the magnesium reduction vertical tank, and install the main crystallization cylinder and the auxiliary crystallization cylinder accordingly. Seal each port through the main crystallization end cap and the auxiliary crystallization end cap. Step B: Turn on and control the circulation water volume of one of the auxiliary cooling water jackets, open the auxiliary vacuum pipe control valve to evacuate the vertical tank, and close the main vacuum pipe control valve. At this time, the powder and trace amounts of magnesium metal vapor in the tank enter the auxiliary crystallizer to begin crystallization. Step C: When the absolute pressure inside the vertical tank reaches 1000-5000 Pa and the temperature of the magnesium raw material balls inside the vertical tank rises to 1080-1190℃, a large amount of magnesium vapor is reduced from the magnesium raw material balls. At this time, reduce the circulation water flow of the auxiliary cooling water jacket and close the auxiliary vacuum pipe; turn on the circulation water flow of the main cooling water jacket and open the control valve of the main vacuum pipe. A large amount of magnesium vapor enters the main crystallizing cylinder to begin crystallization. Step D: After magnesium reduction is complete, close all control valves of the main vacuum pipeline and the auxiliary vacuum pipeline, open the control valve of the vacuum breaking gas inlet pipeline to break the vacuum until atmospheric pressure is reached, and open the main crystallization end cap and the auxiliary crystallization end cap to discharge magnesium and slag.

4. The magnesium crystallization method according to claim 3, characterized in that, Three external branch cylinders are provided on the main body of the cylinder, and a secondary crystallization device is installed at the end of each branch cylinder. In step C, the number of secondary magnesium crystallization devices operating is appropriately controlled according to the changes in the amount of magnesium vapor generated.

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