An apparatus and method for purifying crude magnesium

Abstract

The present invention relates to the technical field of magnesium metal smelting, and particularly relates to an apparatus and method for purifying crude magnesium. By using the apparatus for purifying crude magnesium provided by the present invention, crude magnesium can be purified without the need for an SF6 covering agent, and the produced magnesium has a relatively high purity. The data of the examples show that after the crude magnesium is purified by the apparatus for purifying crude magnesium provided by the present invention, the purity of the product magnesium can reach 99.95%, meeting the requirements for high-purity strategic metal reducing agents and the production of high-end alloys.

Description

Technical Field

[0001] The present invention relates to the technical field of magnesium metal smelting, and particularly to an apparatus and method for purifying crude magnesium. Background Art

[0002] With the rapid development of new energy vehicles, metallic magnesium has been widely used as an important lightweight material, and the quality requirements for magnesium are getting higher and higher. Therefore, effective refining methods are needed to control the melt quality to improve product quality. The traditional method for refining crude magnesium is the flux refining method, which has the advantages of large processing capacity and simple process. However, the disadvantage is that covering agents such as SF 6 etc. need to be added. The degree of warming promoted by SF 6 is 23,500 times that of CO 2 , which is likely to cause environmental pollution. Moreover, the purity of magnesium produced by this method is mostly 99%, and such purity can no longer meet the requirements for high-purity strategic metal reducing agents and high-end alloy production. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide an apparatus and method for purifying crude magnesium. During the process of purifying crude magnesium using the apparatus provided by the present invention, no SF 6 covering agent is required, and the produced magnesium has a relatively high purity.

[0004] The present invention provides an apparatus for purifying crude magnesium, including a feeding system 1;

[0005] a smelting system 2 connected to the feeding system 1; the smelting system 2 includes a refining furnace 21 and a closed melting crucible 22 located in the furnace cavity of the refining furnace 21; a filter hole structure is provided at the bottom of the closed melting crucible 22; a slag discharge port 211 is provided at the bottom of the refining furnace 21, and a refined magnesium outlet 212 is provided at the side; a vertical partition 213 is provided in the furnace cavity of the refining furnace 21, one end of which is in contact with the ground in the furnace cavity; the height of the vertical partition 213 is the same as the distance from the refined magnesium outlet 212 to the bottom of the refining furnace 21; the top end of the vertical partition 213 is higher than the bottom end of the closed melting crucible 22; the slag discharge port 211 and the closed melting crucible 22 are located on the same side of the vertical partition 213; the closed melting crucible 22 and the refined magnesium outlet 212 are located on both sides of the vertical partition 213;

[0006] a magnesium collector 3 connected to the refined magnesium outlet 212 of the smelting system 2;

[0007] a protection system 4 connected to the smelting system 2; the protection system 4 includes a CO 2 storage tank 41 connected to the smelting system 2; an inert gas storage tank 42 connected to the smelting system 2; an air extraction system 43 connected to the smelting system 2.

[0008] Preferably, the equipment for purifying crude magnesium further includes a residue collector 5 communicated with the refining furnace 21 through a slag discharge port 211.

[0009] Preferably, the aperture of the filter hole structure is 5-10 mm.

[0010] The present invention also provides a method for purifying crude magnesium by using the above-mentioned equipment, which includes the following steps:

[0011] Place the magnesium ingot in the closed melting crucible 22, evacuate the smelting system 2 through the air extraction system 43, and then introduce inert gas into the furnace cavity of the refining furnace 21 and the closed melting crucible 22 respectively by using the inert gas storage tank 42, and heat up to obtain molten magnesium.

[0012] Place the crude magnesium and the refining agent in the molten pool formed by the molten magnesium in the closed melting crucible 22, heat up to the smelting temperature for smelting to obtain molten magnesium and residue; during the heating-up process, evacuate the smelting system 2 through the air extraction system 43, and then introduce inert gas into the furnace cavity of the refining furnace 21 and the closed melting crucible 22 respectively by using the inert gas storage tank 42.

[0013] After obtaining the molten magnesium, stop introducing the inert gas, and introduce CO 2 into the closed melting crucible 22 through the CO 2 storage tank 41 to generate a protective film on the surface of the molten magnesium in the closed melting crucible (22).

[0014] The molten magnesium and residue at the bottom of the closed melting crucible 22 settle to one side of the refining furnace 21 through the filter hole structure. After the molten magnesium in the refining furnace 21 overflows to the other side of the vertical partition 213, it flows out through the refined magnesium outlet 212 to the magnesium collector 3.

[0015] The residue is discharged through the slag discharge port 211.

[0016] Preferably, the smelting temperature is 700-800 °C.

[0017] Preferably, the refining agent includes components with the following mass percentages, including MgCl 2 40-60%, KCl 30-50%, NaCl 5-20%, BaCl 2 7-20% and CaF 2 3-20%.

[0018] Preferably, the mass of the refining agent is 2-6% of the mass of the crude magnesium.

[0019] Preferably, the flow rate of the introduced CO 2 is 0.5 L / min, and the time is 7-20 min.

[0020] Preferably, the pressure is increased to 2×10 -1 Pa by inert gas.

[0021] Preferably, before smelting, it also includes drying the crude magnesium and the refining agent; the drying temperature is 200-300°C.

[0022] The present invention provides a device for purifying crude magnesium, including a feeding system 1; a smelting system 2 communicated with the feeding system 1; the smelting system 2 includes a refining furnace 21 and a closed smelting crucible 22 located in the furnace cavity of the refining furnace 21; a filter hole structure is provided at the bottom of the closed smelting crucible 22; a slag discharge port 211 is provided at the bottom of the refining furnace 21, and a refined magnesium outlet 212 is provided on the side; a vertical partition 213 with one end connected to the ground in the furnace cavity is provided in the furnace cavity of the refining furnace 21; the height of the vertical partition 213 is the same as the distance from the refined magnesium outlet 212 to the bottom of the refining furnace 21; the top end of the vertical partition 213 is higher than the bottom end of the closed smelting crucible 22; the slag discharge port 211 and the closed smelting crucible 22 are located on the same side of the vertical partition 213; the closed smelting crucible 22 and the refined magnesium outlet 212 are located on both sides of the vertical partition 213; a magnesium collector 3 communicated with the refined magnesium outlet 212 of the smelting system 2; a protection system 4 communicated with the smelting system 2; the protection system 4 includes a CO 2 storage tank 41; an inert gas storage tank 42 communicated with the smelting system 2; an air extraction system 43 communicated with the smelting system 2. In the present invention, through the primary filtration of the closed smelting crucible 22 and the secondary static filtration of the refined magnesium melt in the refining furnace 21, the purpose of high-efficiency purification is achieved. In addition, the protective film (MgO-C) generated by CO 2 and the magnesium melt effectively replaces the role of the SF 6 covering agent, greatly reducing the environmental pollution problem, and the obtained magnesium purity reaches 99.95%. Therefore, when using the device for purifying crude magnesium provided by the present invention to purify crude magnesium, no SF 6 covering agent is required, and the produced magnesium has a high purity. Description of the Drawings

[0023] Figure 1 It is a schematic diagram of the device for purifying crude magnesium of the present invention; wherein 1 - feeding system; 2 - smelting system; 3 - magnesium collector; 4 - protection system; 5 - residue collector; 11 - feeding bin; 12 - transfer pot; 21 - refining furnace; 22 - closed smelting crucible; 41 - CO 2 storage tank; 42 - inert gas storage tank; 43 - air extraction system; 211 - slag discharge port; 212 - refined magnesium outlet; 213 - vertical partition. Detailed Embodiments

[0024] The present invention provides a device for purifying crude magnesium, including a feeding system 1;

[0025] a smelting system 2 communicated with the feeding system 1; the smelting system 2 includes a refining furnace 21 and an enclosed smelting crucible 22 located in the furnace cavity of the refining furnace 21; a filter hole structure is arranged at the bottom of the enclosed smelting crucible 22; a slag discharge port 211 is arranged at the bottom of the refining furnace 21, and a refined magnesium outlet 212 is arranged at the side of the refining furnace 21; a vertical partition plate 213 with one end connected to the ground in the furnace cavity is arranged in the furnace cavity of the refining furnace 21; the height of the vertical partition plate 213 is the same as the distance from the refined magnesium outlet 212 to the bottom of the refining furnace 21; the top end of the vertical partition plate 213 is higher than the bottom end of the enclosed smelting crucible 22; the slag discharge port 211 and the enclosed smelting crucible 22 are located on the same side of the vertical partition plate 213; the enclosed smelting crucible 22 and the refined magnesium outlet 212 are located on both sides of the vertical partition plate 213;

[0026] a magnesium collector 3 communicated with the refined magnesium outlet 212 of the smelting system 2;

[0027] a protection system 4 communicated with the smelting system 2; the protection system 4 includes a CO 2 storage tank 41 communicated with the smelting system 2; an inert gas storage tank 42 communicated with the smelting system 2; an air extraction system 43 communicated with the smelting system 2.

[0028] In the present invention, if there is no special description, the reagents used are all commercially available products well-known to those skilled in the art.

[0029] The device for purifying crude magnesium provided by the present invention includes a feeding system 1.

[0030] In the present invention, the feeding system 1 includes a feeding bin 11 and a transfer pot 12 communicated with the bottom of the feeding bin 11.

[0031] The device for purifying crude magnesium provided by the present invention includes a smelting system 2 communicated with the feeding system 1.

[0032] In the present invention, the smelting system 2 includes a refining furnace 21; in the present invention, a slag discharge port 211 is arranged at the bottom of the refining furnace 21, and a refined magnesium outlet 212 is arranged at the side of the refining furnace 21. In the present invention, the material of the refining furnace 21 is preferably stainless steel. In the present invention, a vertical partition plate 213 is arranged in the refining furnace 21, and the height of the vertical partition plate 213 is the same as the distance from the refined magnesium outlet 212 to the bottom of the refining furnace 21; the top end of the vertical partition plate 213 is higher than the bottom end of the enclosed smelting crucible 22.

[0033] In the present invention, the smelting system 2 includes a closed melting crucible 22 located in the furnace cavity of the refining furnace 21. In the present invention, a filter hole structure is provided at the bottom of the closed melting crucible 22; the aperture of the filter hole structure is preferably 5 - 10 mm, more preferably 5 - 8 mm. In the present invention, the slag outlet 211 and the closed melting crucible 22 are located on the same side of the vertical partition plate 213. In the present invention, the closed melting crucible 22 and the refined magnesium outlet 212 are located on both sides of the vertical partition plate 213.

[0034] The equipment for purifying crude magnesium provided by the present invention includes a magnesium collector 3 communicated with the refined magnesium outlet 212 of the smelting system 2.

[0035] The equipment for purifying crude magnesium provided by the present invention includes a protection system 4 communicated with the smelting system 2. In the present invention, the protection system 4 includes a CO 2 storage tank 41; an inert gas storage tank 42 communicated with the smelting system 2; an air extraction system 43 communicated with the smelting system 2. In the present invention, the air extraction system 43 is preferably a vacuum pump.

[0036] The equipment for purifying crude magnesium provided by the present invention further includes a residue collector 5 communicated with the refining furnace 21 through the slag outlet 211.

[0037] In the present invention, the equipment for purifying crude magnesium can achieve continuous feeding, thereby realizing large - scale and continuous purification of crude magnesium.

[0038] The present invention also provides a method for purifying crude magnesium by using the above - mentioned equipment, including the following steps:

[0039] Place the magnesium ingot in the closed melting crucible 22, evacuate the smelting system 2 through the air extraction system 43, and then use the inert gas storage tank 42 to introduce inert gas into the furnace cavity of the refining furnace 21 and the closed melting crucible 22 respectively, heat up to obtain molten magnesium;

[0040] Place the crude magnesium and the refining agent in the molten pool formed by the molten magnesium in the closed melting crucible 22, heat up to the smelting temperature for smelting to obtain molten magnesium and residues; during the heating - up process, evacuate the smelting system 2 through the air extraction system 43, and then use the inert gas storage tank 42 to introduce inert gas into the furnace cavity of the refining furnace 21 and the closed melting crucible 22 respectively;

[0041] After obtaining the molten magnesium, stop introducing inert gas, and introduce CO 2 from the storage tank 41 into the closed melting crucible 22 2 to form a protective film on the surface of the molten magnesium in the closed melting crucible (22);

[0042] The molten magnesium and residue at the bottom of the closed melting crucible 22 settle to one side of the refining furnace 21 through the filter hole structure. After the molten magnesium in the refining furnace 21 overflows to the other side of the vertical partition plate 213, it flows out through the refined magnesium outlet 212 to the magnesium collector 3;

[0043] The residue is discharged through the slag outlet 211;

[0044] In the present invention, preferably before smelting, the crude magnesium and the refining agent are also dried. In the present invention, the drying temperature is independently preferably 200-300°C, more preferably 220-250°C. In the present invention, preferably before smelting, the refining furnace 21 is also preheated to a scarlet state.

[0045] In the present invention, the shape of the crude magnesium is preferably block-shaped. In the present invention, the particle size of the refining agent is preferably 0.2-1 mm, more preferably 0.4-0.8 mm. In the present invention, the refining agent comprises the following components in mass percentage, preferably comprising MgCl 2 40-60%, KCl 30-50%, NaCl 5-20%, BaCl 2 7-20% and CaF 2 3-20%; more preferably MgCl 2 50-55%, KCl 35-45%, NaCl 10-15%, BaCl 2 10-15% and CaF 2 5-15%. In the present invention, the mass of the refining agent is preferably 2-6% of the mass of the crude magnesium, more preferably 3-5%. In the present invention, the inert gas preferably comprises argon.

[0046] In the present invention, the flow rate of the introduced CO 2 is preferably 0.5 L / min, and the time is preferably 7-20 min, more preferably 10-15 min. In the present invention, after introducing CO 2 , the molten magnesium and CO 2 react to form a protective film (MgO-C film), and this protective film can cover the surface of the melt to replace the function of the covering agent, avoiding the oxidation of the molten magnesium.

[0047] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0048] Example 1

[0049] Weigh 70 g of magnesium ingots and 150 g of crude magnesium, and dry them at 250 °C for 2 h for later use.

[0050] Weigh 30 g of the refining agent, and the composition of the refining agent is 50 wt.% MgCl 2 , 30 wt.% KCl, 5 wt.% NaCl, 7 wt.% BaCl 2 and 8 wt.% CaF 2 . Dry the refining agent at 200 °C for 2 h for later use.

[0051] After preheating the refining furnace 21 to a bright red color, put the magnesium ingots into the closed melting crucible 22 through the feeding system 1. Vacuum the smelting system 2 through the air extraction system 43, and then introduce argon into the closed melting crucible 22 and the refining furnace 21 through the argon storage tank. Repeat the operations of vacuuming and introducing argon three times, and control the pressure at 2×10 -1 Pa. Heat up to melt the magnesium ingots to obtain molten magnesium (molten pool).

[0052] Put the crude magnesium and the refining agent into the molten pool formed by the molten magnesium in the closed melting crucible 22, heat up to the smelting temperature (700 °C) for smelting. During the heating-up process, vacuum the smelting system 2 through the air extraction system 43, and then use the inert gas storage tank 42 to introduce inert gas into the furnace cavity of the refining furnace 21 and the closed melting crucible 22 respectively. Repeat the operations of vacuuming and introducing argon three times, and control the pressure at 2×10 -1 Pa. After the crude magnesium melts, stop introducing the inert gas, and introduce CO 2 into the closed melting crucible through the CO 2 storage tank 41 for 10 min to form a protective film on the surface of the molten magnesium, and then stop introducing CO 2 ;

[0053] The pure molten magnesium and the residue at the bottom of the closed melting crucible 22 settle to one side of the refining furnace 21 through the filter hole structure, and the molten magnesium in the refining furnace 21 flows to the other side of the vertical partition board; then, after evacuating the magnesium collector 3, flow the molten magnesium out through the refined magnesium outlet 212 to the magnesium collector 3; the residue is discharged through the slag outlet 211.

[0054] The purity of the magnesium obtained by purification in Example 1 of the present invention is 99.95%.

[0055] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An apparatus for purifying crude magnesium, comprising a feeding system (1); A smelting system (2) communicated with the feeding system (1); the smelting system (2) includes a refining furnace (21) and an enclosed smelting crucible (22) located in the furnace cavity of the refining furnace (21); a filter hole is provided at the bottom of the enclosed smelting crucible (22); a slag discharge port (211) is provided at the bottom of the refining furnace (21), and a refined magnesium outlet (212) is provided at the side; a vertical partition plate (213) with one end connected to the inner bottom surface of the furnace cavity is provided in the furnace cavity of the refining furnace (21); the height of the vertical partition plate (213) is the same as the distance from the refined magnesium outlet (212) to the bottom of the refining furnace (21); the top end of the vertical partition plate (213) is higher than the bottom end of the enclosed smelting crucible (22); the slag discharge port (211) and the enclosed smelting crucible (22) are located on the same side of the vertical partition plate (213); the enclosed smelting crucible (22) and the refined magnesium outlet (212) are located on both sides of the vertical partition plate (213); A magnesium collector (3) communicated with the refined magnesium outlet (212) of the smelting system (2); A protection system (4) connected to the smelting system (2); the protection system (4) includes a CO 2 storage tank (41) connected to the smelting system (2); an inert gas storage tank (42) connected to the smelting system (2); an air extraction system (43) connected to the smelting system (2).

2. The apparatus according to claim 1, wherein, the apparatus for purifying crude magnesium further includes a residue collector (5) communicated with the refining furnace (21) through the slag discharge port (211).

3. The apparatus according to claim 1 or 2, wherein, the aperture of the filter hole is 5 - 10 mm.

4. A method for purifying crude magnesium using the apparatus according to any one of claims 1 - 3, wherein, it includes the following steps: Placing magnesium ingots in the enclosed smelting crucible (22), evacuating the smelting system (2) through an air extraction system (43), and then introducing inert gas into the furnace cavity of the refining furnace (21) and the enclosed smelting crucible (22) respectively using an inert gas storage tank (42), heating to obtain molten magnesium; Placing crude magnesium and a refining agent in the molten pool formed by the molten magnesium in the enclosed smelting crucible (22), heating and raising the temperature to the smelting temperature for smelting to obtain a magnesium melt and residues; during the process of heating and raising the temperature, evacuating the smelting system (2) through the air extraction system (43), and then introducing inert gas into the furnace cavity of the refining furnace (21) and the enclosed smelting crucible (22) respectively using the inert gas storage tank (42); After obtaining the molten magnesium, stop introducing the inert gas, and introduce CO 2 from the storage tank (41) into the closed melting crucible (22). 2 A protective film is formed on the surface of the molten magnesium in the closed melting crucible (22). The molten magnesium and residues at the bottom of the enclosed smelting crucible (22) settle to one side of the refining furnace (21) through the filter hole structure. After the molten magnesium in the refining furnace (21) overflows to the other side of the vertical partition plate (213), it flows out through the refined magnesium outlet (212) into the magnesium collector (3); The residues are discharged through the slag discharge port (211).

5. The method according to claim 4, wherein, the smelting temperature is 700 - 800 °C.

6. The method according to claim 4, wherein, The refining agent comprises components with the following mass percentages: MgCl 2 40 - 60%, KCl 30 - 50%, NaCl 5 - 20%, BaCl 2 7 - 20% and CaF 2 3 - 20%.

7. The method according to claim 4, wherein, the mass of the refining agent is 2 - 6% of the mass of the crude magnesium.

8. The method according to claim 4, wherein, The introduced CO 2 has a flow rate of 0.5 L / min and a time of 7 to 20 minutes.

9. The method according to claim 4, wherein, The inert gas is introduced until the pressure reaches 2×10 -1 Pa.

10. The method according to claim 4, characterized in that, before smelting, it further includes drying the crude magnesium and the refining agent; the temperature of the drying is 200~300°C.

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