Vacuum melting and casting system and process method for producing high-purity oxygen-free copper

Abstract

The invention relates to the technical field of metallurgical purification, in particular to a vacuum melting and casting system and a process method for producing high-purity oxygen-free copper. The vacuum melting and casting system comprises a vacuum melting furnace, a graphite crucible, a cast ingot directional solidification device and a pouring assembly, the graphite crucible, the cast ingot directional solidification device and the tilting mechanism are arranged in the vacuum melting furnace, and the pouring assembly is used for moving and tilting the graphite crucible; the cast ingot directional solidification device comprises an ingot mold, the ingot mold comprises a side wall and a base, a heat preservation inner sleeve is arranged on the inner side wall of the ingot mold, and a graphite gasket is arranged on the inner bottom face of the ingot mold. The large-size high-purity copper cast ingot is prepared through vacuum casting and directional solidification, the purity of the copper cast ingot is effectively improved, copper impurities can be reduced through vacuum melting, and impurity elements are enriched at the tail end of the top of the cast ingot in the heat flow direction in the directional solidification process through directional solidification; and after the part is cut off, the high-purity large-size copper cast ingot can be obtained, the technological method is simple, and the production period is greatly shortened.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical purification, and in particular to a vacuum melting and casting system and a process for producing high-purity oxygen-free copper. Background Art

[0002] High-purity copper is widely used in electronics, communications, defense and other industries due to its excellent electrical and thermal conductivity and processing properties. However, the presence of trace impurity elements has a great impact on the electrical conductivity and deep processing properties of copper. Among them, elements such as P, Fe, and S have a greater impact on the electrical conductivity of copper. Impurity elements such as Zn, Sb, and As dissolved in copper have a cumulative effect on its conductivity. Pb, Bi, etc. will form a low-melting-point eutectic with copper, causing the material to become "hot brittle".

[0003] In order to improve the electrical conductivity, thermal conductivity and stability of copper materials, it is necessary to reduce the content of impurity elements in the material to obtain high-purity copper materials.

[0004] Patent CN118086979A uses copper nitrate with a concentration of 250-300g / L and nitric acid with an electrolyte with a concentration of 150-170g / L, selects 4N electrolytic copper as the anode plate, and selects a titanium plate as the cathode plate to prepare high-purity copper by electrolytic refining. However, the preparation method disclosed in the patent has a complex production process, low production efficiency, and unstable product quality; Patent CN103966442B uses an anion exchange method to prepare high-purity copper above 4N, but this method has high energy consumption and causes great pollution to the environment.

[0005] In summary, the process for preparing high-purity copper materials in the prior art is complex and has a long production cycle, and large-sized copper ingots cannot be obtained. Summary of the invention

[0006] In order to solve the above technical problems existing in the prior art, the present invention provides a vacuum melting and casting system and a process method for producing high-purity oxygen-free copper.

[0007] The technical solution of the present invention to solve the above technical problems is as follows:

[0008] A first aspect of the present invention is to provide a vacuum melting and casting system, comprising a vacuum melting furnace, a graphite crucible, an ingot directional solidification device and a dumping assembly, wherein the graphite crucible, the ingot directional solidification device and the tilting mechanism are arranged in the vacuum melting furnace, and the dumping assembly is used for moving and tilting the graphite crucible; the ingot directional solidification device comprises an ingot mold, the ingot mold comprises side walls and a base, the inner side wall of the ingot mold is provided with an insulating inner sleeve, and the inner bottom surface of the ingot mold is provided with a graphite gasket.

[0009] By adopting the vacuum melting and casting system provided by the present invention, directional solidification occurs by utilizing the difference in segregation coefficients of elements in the solid-liquid phase, and the directional solidification process is completed from the bottom to the top of the ingot mold, so that the impurity elements are enriched at the top end of the ingot along the heat flow direction during the directional solidification process, and a high-purity large-sized copper ingot can be obtained by cutting off this part. The process method is simple, and the production cycle is greatly shortened. The graphite gasket plays a role of isolating the ingot from the ingot mold base to prevent the copper water from being contaminated. At the same time, the graphite gasket dissipates heat quickly, plays a role of rapid heat dissipation, and ensures directional solidification.

[0010] On the basis of the above technical solution, the present invention can also make the following improvements:

[0011] Furthermore, the outer side wall of the ingot mold is provided with a heat-insulating layer.

[0012] The beneficial effect of adopting the above further technical solution is: further reducing the heat dissipation of the side wall of the ingot mold, so that the heat dissipation is gradually completed from the bottom to the top of the ingot mold, ensuring directional solidification along a specific direction.

[0013] Furthermore, the side wall thickness of the ingot mold is smaller than the base thickness.

[0014] The beneficial effect of adopting the above further technical solution is: further increase the heat dissipation at the bottom of the ingot mold and reduce the heat dissipation at the side wall, so that the heat dissipation is gradually completed from the bottom to the top of the ingot mold, ensuring directional solidification along a specific direction.

[0015] Furthermore, the side wall thickness of the ingot mold is 50-60 mm, and the base thickness is 70-80 mm; the base diameter of the ingot mold is 120-140 mm.

[0016] The beneficial effect of adopting the above further technical solution is that a large-sized base is used to increase the heat dissipation at the bottom of the ingot mold, ensure directional solidification, and obtain a large-sized ingot.

[0017] Furthermore, the inner diameter of the thermal insulation inner sleeve decreases from an end close to the base to an end far away from the base.

[0018] The beneficial effect of adopting the above-mentioned further technical scheme is that: through the design of the inner diameter size of the insulating inner sleeve, the size of the ingot is ensured to decrease from the end close to the base to the end away from the base, which is convenient for demolding the ingot; at the same time, the inner diameter of the insulating inner sleeve gradually decreases from the end close to the base to the end away from the base, which can further ensure that the directional solidification process is completed from the bottom to the top of the ingot mold.

[0019] Furthermore, the thermal insulation inner sleeve includes a first part and a second part which are connected, the first part is arranged close to the base, the second part is arranged far from the base, the inner diameter of the first part close to the second part is d1, the inner diameter of the second part close to the first part is d2, and d2>d1.

[0020] The beneficial effect of adopting the above further technical solution is to ensure that the ingot size is increased suddenly in the riser area, so that the riser size is increased to facilitate demoulding.

[0021] Furthermore, a pouring mechanism is provided on the top of the ingot directional solidification device, one end of the pouring mechanism is connected to the interior of the insulation inner sleeve, and the other end is close to the graphite crucible, and an opening is provided at the end of the pouring mechanism close to the graphite crucible.

[0022] The beneficial effect of adopting the above further technical solution is that: it is easy to realize pouring molten copper from the graphite crucible into the ingot directional solidification device, and after smelting, the graphite crucible can be tilted to pour the molten copper into the ingot directional solidification device through the opening and the pouring mechanism, thereby realizing the directional solidification of the molten copper; vacuum smelting and casting are completed under vacuum conditions in the vacuum smelting furnace, thereby successfully producing a high-purity oxygen-free copper ingot.

[0023] Furthermore, the outer side wall of the ingot mold is provided with a clamping mechanism or a lifting mechanism.

[0024] The beneficial effect of adopting the above further technical solution is that it is easy to lift or clamp the ingot mold, so as to demould the ingot.

[0025] Another aspect of the present invention is to provide a process for producing high-purity oxygen-free copper using the above vacuum melting and casting system.

[0026] Further, the process for producing high-purity oxygen-free copper comprises the following steps:

[0027] S1. Place the electrolytic copper in a graphite crucible, heat it to 1100-1200°C until the electrolytic copper is completely melted, then heat it to 1300-1400°C and refine it in a vacuum environment for 10-30 minutes;

[0028] S2, pouring the molten copper obtained in step S1 into an ingot directional solidification device, and after the pouring is completed, standing for 20-60 minutes, and filling with nitrogen to break the vacuum;

[0029] S3, demoulding the copper ingot and cutting off the riser portion at the top to obtain the high-purity oxygen-free copper.

[0030] Compared with the prior art, the present invention has the following technical effects: the vacuum melting and casting system provided by the present invention prepares large-sized high-purity copper ingots through vacuum melting and directional solidification, which effectively improves the purity of the copper ingots. Vacuum melting can reduce copper impurities, and then through directional solidification, the impurity elements are enriched at the top end of the ingot along the heat flow direction during the directional solidification process. By cutting off this part, a high-purity large-sized copper ingot can be obtained. The process method is simple and the production cycle is greatly shortened. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic structural diagram of a vacuum melting and casting system according to Embodiment 1 of the present invention is shown;

[0032] Figure 2 A schematic structural diagram of an ingot directional solidification device according to Embodiment 1 of the present invention is shown;

[0033] Figure 3 A schematic structural diagram of a dumping assembly according to Embodiment 1 of the present invention is shown;

[0034] 1. Ingot mold; 2. Insulation inner sleeve; 3. Graphite gasket; 4. Casting material; 5. Vacuum melting furnace; 6. Graphite crucible; 7. Lifting ear; 8. Ingot directional solidification device; 9. Pouring mechanism; 10. Dumping assembly; 11. Vertical moving mechanism; 12. Support member; 13. Rolling member; 14. Connecting member. DETAILED DESCRIPTION

[0035] The following specific embodiments illustrate the implementation of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this implementation. On the contrary, the purpose of introducing the invention in conjunction with the implementation is to cover other options or modifications that may extend based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0036] Example 1

[0037] See also Figure 1 , Figure 2 , Figure 3A vacuum melting and casting system comprises a vacuum melting furnace 5, a graphite crucible 6, an ingot directional solidification device 8 and a dumping assembly 10, wherein the graphite crucible 6, the ingot directional solidification device 8 and the tilting mechanism are arranged in the vacuum melting furnace 5, and the dumping assembly 10 is used for moving and tilting the graphite crucible 6, so as to dump the molten copper in the graphite crucible 6 into the ingot directional solidification device 8; the ingot directional solidification device 8 comprises an ingot mold 1, wherein the ingot mold 1 comprises a side wall and a base, and the inner side wall of the ingot mold 1 is provided with an insulating inner sleeve 2, and the insulating inner sleeve 2 is a corundum inner sleeve, and a casting material 4 for bonding the ingot mold 1 and the insulating inner sleeve 2 is provided between the inner side wall of the ingot mold 1 and the insulating inner sleeve 2, so that the ingot mold 1 and the insulating inner sleeve 2 are tightly fitted, and a graphite gasket 3 is provided on the inner bottom surface of the ingot mold 1, and the graphite gasket 3 serves to isolate the ingot from the base of the ingot mold 1 to prevent the copper water from being contaminated. At the same time, the graphite gasket dissipates heat quickly, plays a role in rapid heat dissipation, and ensures directional solidification; the inner diameter of the thermal insulation inner sleeve 2 decreases from the end close to the base to the end away from the base. The thermal insulation inner sleeve 2 includes a first part and a second part that are connected. The first part is arranged close to the base, and the second part is arranged away from the base. The inner diameter of the first part close to the second part is d1, and the inner diameter of the second part close to the first part is d2, and d2>d1. Such an arrangement can ensure that the directional solidification process is completed from the bottom to the top of the ingot mold 1, and it is convenient for the ingot to be demolded; the outer wall of the ingot mold 1 is provided with thermal insulation cotton, the side wall thickness of the ingot mold 1 is 50mm, the thickness of the thermal insulation inner sleeve 2 is 50mm, the thickness of the base is 70mm, and the diameter of the base is 120mm.

[0038] By increasing the side wall thickness of the ingot mold 1, adding an insulating inner sleeve 2 with a thermal insulation effect to the inner wall, and covering the outer wall with thermal insulation cotton, the side wall of the ingot mold 1 is insulated to reduce heat dissipation, so that the cooling of the molten copper starts from the bottom. By setting a large-size and thick ingot mold 1 base and a graphite gasket 3 with fast heat dissipation, the bottom heat dissipation is increased. During the cooling process, the heat is gradually dissipated from the bottom of the ingot mold 1 to the top, thereby achieving directional solidification of the ingot from the bottom to the top, so that the impurity elements in the copper are enriched at the top end of the ingot. After solidification is completed, the ingot is demoulded, and a high-purity copper ingot can be obtained by cutting off the top riser part.

[0039] A pouring mechanism 9 is provided on the top of the ingot directional solidification device 8, one end of the pouring mechanism 9 is connected to the interior of the heat-insulating inner sleeve 2, and the other end is arranged near the graphite crucible 6, and an opening is provided at the end of the pouring mechanism 9 near the graphite crucible 6, and the molten copper enters the pouring mechanism 9 through the opening, and then flows into the ingot directional solidification device 8 for directional solidification; specifically, electrolytic copper is placed in the graphite crucible 6, and the temperature in the vacuum melting furnace 5 is increased so that the electrolytic copper is refined under vacuum conditions to obtain molten copper, and the molten copper is poured into the ingot directional solidification device 8 to complete the directional solidification of the ingot. After the solidification is completed to form an ingot, the ingot directional solidification device 8 is taken out of the vacuum melting furnace 5 through the lifting ear 7 by a tool, and a high-purity copper ingot is obtained after demoulding and cutting off the upper riser part.

[0040] The dumping assembly 10 includes a vertical moving mechanism 11, a support member 12, a rolling member 13 and a connecting member 14. The vertical moving mechanism 11 is connected to the support member 12, and the vertical moving mechanism 11 controls the support member 12 to move in the vertical direction, so as to control the vertical height of the graphite crucible 6; one end of the connecting member 14 is fixedly connected to the graphite crucible 6, and the other end is hinged to the rolling member 13. The rolling member 13 is semicircular, and the straight edge end of the rolling member 13 is hinged to the connecting member 14, which is used to change the angle of the graphite crucible 6 for facilitating the pouring of molten copper; the arc end of the rolling member 13 is rolled on the support member 12, so as to approach or move away from the ingot directional solidification device 8, and the support member 12 is provided with a groove for the rolling of the rolling member 13. The vertical moving mechanism 11 is a cylinder, and the vertical movement of the vertical moving mechanism 11, the rolling of the rolling member 13 on the supporting member 12, and the rotation between the rolling member 13 and the connecting member 14 are realized by a control mechanism arranged outside the vacuum melting furnace 5. Specifically, first, the vertical moving mechanism 11 drives the graphite crucible 6 to move to an appropriate position in the vertical direction, and then the rolling member 13 moves to drive the graphite crucible 6 to approach the ingot directional solidification device 8, and finally the connecting member 14 drives the graphite crucible 6 to rotate relative to the rolling member 13, so as to realize the pouring of molten copper; in the whole process, the pouring assembly 10 drives the graphite crucible 6 to move to an appropriate position and rotate it by a certain angle, so as to facilitate the pouring of the molten copper in the graphite crucible 6 into the ingot directional solidification device 8.

[0041] Example 2

[0042] A process for producing high-purity oxygen-free copper using the vacuum melting and casting system of Example 1 comprises the following steps:

[0043] S1. Put the electrolytic copper into a graphite crucible, heat it to 1100°C until the electrolytic copper is completely melted, then heat it to 1400°C and refine it in a vacuum environment for 30 minutes;

[0044] S2, pouring the molten copper obtained in step S1 into an ingot directional solidification device, and after the pouring is completed, standing for 260 minutes, and filling with nitrogen to break the vacuum;

[0045] S3, demoulding the copper ingot and cutting off the riser portion at the top to obtain the high-purity oxygen-free copper.

[0046] The composition content of the high-purity oxygen-free copper ingot obtained in Example 2 is shown in Table 1.

[0047] Table 1 Composition content of high purity oxygen-free copper ingot of Example 2

[0048]

[0049]

[0050] According to the high-purity oxygen-free copper ingot prepared in the embodiment of the present invention, certain impurities are reduced by vacuum refining, and then the impurities are floated to the upper part of the ingot by directional solidification, so that the bottom of the ingot reaches the purity requirement of 5N.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A vacuum melting and casting system, characterized in that: It comprises a vacuum melting furnace, a graphite crucible, an ingot directional solidification device and a dumping assembly, wherein the graphite crucible, the ingot directional solidification device and the tilting mechanism are arranged in the vacuum melting furnace, and the dumping assembly is used for moving and tilting the graphite crucible; the ingot directional solidification device comprises an ingot mold, wherein the ingot mold comprises a side wall and a base, the inner side wall of the ingot mold is provided with a heat-insulating inner sleeve, and the inner bottom surface of the ingot mold is provided with a graphite gasket.

2. The vacuum melting and casting system according to claim 1, characterized in that: The outer side wall of the ingot mold is provided with a heat-insulating layer.

3. The vacuum melting and casting system according to claim 1, characterized in that: The side wall thickness of the ingot mold is smaller than the base thickness.

4. The vacuum melting and casting system according to claim 3, characterized in that: The side wall thickness of the ingot mold is 50-60 mm, and the base thickness is 70-80 mm; the base diameter of the ingot mold is 120-140 mm.

5. The vacuum melting and casting system according to claim 1, characterized in that: The inner diameter of the heat-insulating inner sleeve decreases from an end close to the base to an end far away from the base.

6. The vacuum melting and casting system according to claim 5, characterized in that: The thermal insulation inner sleeve includes a first part and a second part which are connected. The first part is arranged close to the base, and the second part is arranged far from the base. The inner diameter of the first part close to the second part is d1, and the inner diameter of the second part close to the first part is d2, and d2>d1.

7. The vacuum melting and casting system according to claim 1, characterized in that: A pouring mechanism is provided on the top of the ingot directional solidification device, one end of the pouring mechanism is connected to the interior of the heat-insulating inner sleeve, and the other end is close to the graphite crucible, and an opening is provided at the end of the pouring mechanism close to the graphite crucible.

8. The vacuum melting and casting system according to claim 1, characterized in that: The outer side wall of the ingot mold is provided with a clamping mechanism or a hoisting mechanism.

9. A process for producing high-purity oxygen-free copper, characterized in that: Use the vacuum melting and casting system according to any one of claims 1 to 8.

10. The process for producing high-purity oxygen-free copper according to claim 9, characterized in that: The following steps are involved: S1. Place the electrolytic copper in a graphite crucible, heat it to 1100-1200°C until the electrolytic copper is completely melted, then heat it to 1300-1400°C and refine it in a vacuum environment for 10-30 minutes; S2, pouring the molten copper obtained in step S1 into an ingot directional solidification device, and after the pouring is completed, standing for 20-60 minutes, and filling with nitrogen to break the vacuum; S3, demoulding the copper ingot and cutting off the riser portion at the top to obtain the high-purity oxygen-free copper.

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