A preparation method for a large-size high-purity copper ingot

Abstract

The present invention belongs to the technical field of metal material casting, and specifically relates to a method for preparing large-sized high-purity copper ingots. The present invention provides a casting process using a short crystallizer and a ring-shaped water baffle, which enhances the water cooling effect, enables the ingot to cool down faster, and prevents grain growth, thereby obtaining an ingot with a uniform and fine structure. The method for preparing the ingot with a uniform and fine structure provided by the present invention has good operability, high production efficiency, low production cost, and can achieve industrialized mass production.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material casting, and specifically relates to a method for preparing large-size high-purity copper ingots, especially a method for preparing large-size high-purity copper ingots with a diameter greater than 260 mm. Background Art

[0002] Due to its good electrical conductivity, thermal conductivity and corrosion resistance, pure copper is widely used in various industries. In recent years, with the rapid development of the semiconductor industry, large-size high-purity copper sputtering targets, high-purity copper superconducting materials, etc. have been continuously applied, and the usage amount has been increasing year by year; the common feature of these materials is that the comprehensive technical indicators are very high, especially the requirements for the internal tissue uniformity and the zero tolerance for defects, which pose severe challenges to the products prepared by traditional process methods.

[0003] Research has found that for the preparation of such high-quality products, regardless of the specification size, large-size ingot billets can be prepared by melting and casting, and then further processed into the required products; for example, large-size high-purity copper sputtering targets or high-purity copper superconducting materials, in the manufacturing process, it is easy to select large-size round ingots as billets, and then processed into the required products by extrusion or forging, etc.; therefore, the quality of large-size ingots is crucial, especially the uniformity of the internal tissue and the grain size, which not only affect their processing performance, but also affect the quality of the processed products. It can be said that the more uniform and finer the internal tissue of the ingot, the better its reprocessing performance and the quality of the processed products. However, the actual situation is that the larger the ingot size, the more difficult it is to control the uniformity of the internal tissue and the larger the grains.

[0004] Generally, for ingots with higher purity and larger size, their grain structures are more prone to coarsening. Because the purer the metal, the lower the nucleation rate during crystallization, the larger the grains. At the same time, the larger the size, the slower the cooling rate, and the easier the grains are to grow. Therefore, the grains of large-sized high-purity copper ingots are prone to coarsening. The typical characteristics of pure copper ingots continuously cast by traditional processes are "coarse equiaxed grains in the core, well-developed columnar grains in the middle, and relatively fine equiaxed grains at the edge" or "coarse equiaxed grains in the core, well-developed columnar grains from the middle to the edge". Especially for larger-diameter ingots, the cooling rate is relatively slow, and the columnar grains are more developed. Such ingots with extremely uneven and coarse structures are very unfavorable for further processing, with poor plasticity, even cracking during processing, and the processed products are prone to residual coarse dendrite traces in the structure, and the properties of different parts of the processed products are prone to unevenness, etc. To obtain large-sized high-purity copper ingots with uniform and fine internal structures, from a metallurgical analysis, it is necessary to start from two aspects: one is to increase the supercooling degree during the crystallization of high-temperature liquid metal to promote a large number of nucleations and refine the grains, and the other is to prevent the grains from growing after nucleation and crystallization. To achieve the purpose of grain refinement, the existing process uses electromagnetic vibration casting. The ingots obtained by this method have improved casting quality and relatively fine grain structures, but its production cost is relatively high, and the coils of the electromagnetic vibration system are easily damaged and troublesome to replace, which brings inconvenience to production.

[0005] Therefore, it is necessary to develop a new method for preparing large-sized high-purity copper ingots, starting from solving the internal quality of large-sized ingots and aiming at obtaining large-sized high-purity copper ingots with uniform, fine internal structures and no defects. Summary of the Invention

[0006] The present invention provides a method for preparing a large-sized high-purity copper ingot, aiming to solve the problem of coarse and uneven internal structures of large-sized high-purity copper ingots, preparing ingots with uniform and fine structures, and meeting the requirements for processing high-quality products, such as ingots required for processing large-sized high-purity copper rotating targets, high-purity copper superconducting materials, etc. The present invention provides a casting process using a short mold and installing and using an annular water baffle to achieve the goal of preparing large-sized high-purity copper ingots with uniform, fine internal structures and no defects.

[0007] To achieve the above object, the technical solutions provided by the present invention are as follows.

[0008] A method for preparing a large-sized high-purity copper ingot includes the following steps:

[0009] Step 1: Install a short mold on a movable casting trolley, with the center line of the short mold perpendicular to the ground plane; the annular water baffle is installed directly below the short mold by welding, and the annular water baffle is on the same center line as the short mold;

[0010] Step 2: Raise the ingot guiding system that holds the ingot in the casting well, and finely adjust the movable casting trolley to insert the ingot head of the ingot guiding system into the short mold;

[0011] Step 3: Preheat the graphite tube. Insert one end of the preheated graphite tube into the furnace head of the melting furnace and lock it firmly. Tilt the furnace head so that the other end of the graphite tube inserts into the center of the short crystallizer. A flow-limiting valve is installed at the graphite tube inserted into the furnace head end, and the flow-limiting valve is in the closed state at this time.

[0012] Step 4: Tilt the furnace body so that the copper liquid flows into the furnace head. Heat the furnace head for a certain period of time, then adjust the temperature of the copper liquid, let it stand for a certain period of time and keep it warm. Adjust the furnace body so that the graphite tube inserted into the furnace head is aligned with the center of the short crystallizer and perpendicular to the horizontal plane of the short crystallizer.

[0013] Step 5: Open the flow-limiting valve. The copper liquid enters the short crystallizer through the graphite tube. Immediately after the copper liquid enters the short crystallizer, make the cooling water enter the cavity through the water inlet of the short crystallizer. The pressure of the cooling water is 0.17 MPa - 0.25 MPa. Conduct initial casting, and the initial casting speed is half of the stable casting speed. When the liquid level of the copper liquid in the short crystallizer is 30 mm - 40 mm away from the upper edge of the short crystallizer, enter stable casting. At this time, the graphite tube is immersed in the copper liquid in the short crystallizer, and the stable casting speed is 5.6 m / h - 6.3 m / h.

[0014] Step 6: The dummy head of the dummy bar system lifts the ingot and moves it downward. The cooling water sprays out through the water outlet holes of the short crystallizer and splashes onto the surface of the lifted ingot. The cooling water on the surface of the ingot is refracted onto the annular water baffle, and then refracted onto the surface of the ingot again, repeating this process many times. Continuously cast without interruption. When the copper liquid in the melting furnace is poured out or the length of the ingot reaches the set value, the casting ends, and the ingot is taken out to obtain a large-sized high-purity copper ingot.

[0015] Further, in Step 1, the short crystallizer 1 includes an inner sleeve 101; an outer sleeve 102 is sleeved outside the inner sleeve 101, and a cavity is formed between the outer sleeve 102 and the inner sleeve 101; a water inlet 103 is provided on the side wall of the outer sleeve 102, and the water inlet 103 is communicated with the cavity; a plurality of water outlet holes 104 are provided at the junction of the lower edge of the outer sleeve 102 and the inner sleeve 101. The water outlet holes 104 are semi-circular, the water outlet holes 104 are communicated with the cavity, and the water outlet holes 104 are evenly distributed in the circumferential direction of the lower edge of the outer sleeve 102.

[0016] Further, the distance between the centers of every two adjacent water outlet holes 104 is 9 mm - 9.5 mm, the center line of the water outlet hole 104 forms an angle of 45º - 60º with the horizontal plane, the diameter of the water outlet hole 104 is 4 mm - 6 mm, and the height of the short crystallizer 1 is 130 mm - 180 mm.

[0017] Further, in Step 1, the preparation of the annular water baffle 2: After rolling a rectangular metal plate into a cylinder, weld the seam to obtain the annular water baffle 2; the rectangular metal plate is made of iron or ordinary carbon steel, the thickness of the rectangular metal plate is 2 mm to 4 mm, the height of the annular water baffle 2 is 130 mm to 200 mm, and the inner diameter of the annular water baffle 2 is 10 mm to 25 mm larger than the diameter of the lower edge of the inner sleeve.

[0018] Further, in Step 1, the distance between the annular water baffle 2 and the short mold 1 is 10 mm to 20 mm.

[0019] Further, in Step 2, the dummy bar head stops at the 1 / 3 position from the lower edge of the short mold 1, and use asbestos cloth to block the gap between the dummy bar head and the short mold 1.

[0020] Further, in Step 3, one end of the graphite tube inserted into the center of the short mold is set at a position 50 mm to 55 mm from the upper edge of the short mold 1, and the graphite tube is perpendicular to the horizontal plane of the short mold 1.

[0021] Further, in Step 4, the time for heating the furnace head is 20 minutes to 30 minutes, the temperature of the copper liquid is adjusted to 1195 °C to 1215 °C, and the standing time is 3 minutes to 5 minutes.

[0022] Further, in Step 5, use roasted red soot to cover the copper liquid in the short mold.

[0023] By studying the characteristics of metal crystallization, namely the nucleation and growth mechanism, the present invention studies how to achieve a large number of nucleations during the crystallization of liquid metal at high temperature and slow grain growth after nucleation, so as to achieve the purpose of refining grains, making the ingot conducive to subsequent reprocessing, and producing higher-quality products.

[0024] The principle of the method of the present invention: After the liquid metal crystallizes into a shell in the short mold to form the ingot prototype, under the condition of a certain casting speed, by adopting continuous casting with a short mold, the ingot can be continuously and more quickly lifted out of the short mold, shortening the residence time of the high-temperature ingot in the short mold. At the same time, the ingot separated from the short mold is immediately directly cooled by the water sprayed out of the short mold, promoting more nucleation of the liquid metal in the uncrystallized area inside the ingot when encountering strong cooling, and also quickly cooling the crystallized metal to prevent grain growth; by installing and using the annular water baffle, the water sprayed onto the surface of the ingot is refracted, splashed onto the water baffle surrounding the ingot, and then refracted from the water baffle to the surface of the ingot again. The water is refracted onto the surface of the ingot repeatedly in this way, strengthening the water cooling effect, making the ingot cool faster and preventing grain growth, so as to obtain an ingot with uniform and fine structure. The method for preparing an ingot with uniform and fine structure provided by the present invention has good operability, high production efficiency, low production cost, and can form industrial mass production.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0026] (1) Characteristics of short mold casting: The height of the short mold is 130 - 180 mm, which shortens the residence time of the high-temperature ingot in the short mold under continuous casting conditions. During casting, water enters the cavity through the water inlet, causing the molten copper to crystallize into a shell. The discharged water is directly sprayed onto the ingot lifted out of the short mold to strongly cool the ingot.

[0027] (2) An annular water baffle is installed below the short mold. When the water sprayed from the short mold reaches the surface of the ingot, it refracts. The refracted water sprays onto the inner ring surface of the annular water baffle and then refracts again to the surface of the ingot. The ingot is cooled again. The cooling water refracts repeatedly in this way, which is equivalent to continuously spraying water to cool the ingot multiple times, enhancing the cooling effect, enabling the ingot to cool down faster, and preventing the growth of internal grains.

[0028] (3) For this process technical solution, the existing furnace head casting continuous casting in general non-ferrous metal processing enterprises can be fully utilized without additional investment, and high-quality ingots can be cast at low cost. The structure of the ingot is uniform and fine, and the operation is convenient, clean, and environmentally friendly. Description of the Drawings

[0029] Figure 1 Schematic cross-sectional structure diagram of the short mold adapted to the annular water baffle.

[0030] Figure 2 Schematic cross-sectional diagram of the short mold.

[0031] Figure 3 Schematic diagram of the bottom surface structure of the mold.

[0032] Figure 4 Comparative diagram of the cross-sectional structure of ∮330 mm ingots prepared by Example 2 and the prior art (a, Example 1; b, prior art).

[0033] Labels: 1, short mold; 101, inner sleeve; 102, outer sleeve; 103, water inlet; 104, water outlet hole; 2, annular water baffle; 3, metal rod. Detailed Embodiments

[0034] Next, the technical solution of the present invention will be clearly and completely described in conjunction with the attached Figures 1 - 4 drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] A method for preparing a large-size high-purity copper ingot includes the following steps:

[0036] Step 1: Install the short crystallizer on the movable casting trolley, with the center line of the short crystallizer perpendicular to the ground plane; weld and install the annular water baffle directly below the crystallizer with a metal rod. The distance between the annular water baffle and the short crystallizer is 10 mm to 20 mm, and they are on the same center line as the crystallizer.

[0037] Step 2: Raise the dummy bar system that holds the ingot in the casting well, and finely adjust the movable casting trolley so that the dummy bar head of the dummy bar system inserts into the short crystallizer. The dummy bar head stops at the position of 1 / 3 of the distance from the lower edge of the short crystallizer, and block the gap between the dummy bar head and the short crystallizer with asbestos cloth.

[0038] Step 3: Preheat the graphite tube. Insert one end of the preheated graphite tube into the furnace head of the melting furnace and lock it firmly. Tilt the furnace head so that the other end of the graphite tube inserts into the center of the short crystallizer. The end of the graphite tube inserted into the center of the short crystallizer is set at a position 50 mm to 55 mm from the upper edge of the short crystallizer. The graphite tube is perpendicular to the horizontal plane of the short crystallizer. A flow limiting valve is installed at the end of the graphite tube inserted into the furnace head, and the flow limiting valve is in the closed state at this time.

[0039] Step 4: Tilt the furnace body, let the copper liquid flow into the furnace head, heat the furnace head for 20 minutes to 30 minutes, then adjust the temperature of the copper liquid to 1195°C to 1215°C, let it stand for 3 minutes to 5 minutes and keep it warm. Adjust the furnace body so that the graphite tube inserted into the furnace head is aligned with the center of the short crystallizer and perpendicular to the horizontal plane of the short crystallizer.

[0040] Step 5: Open the flow limiting valve. The copper liquid enters the short crystallizer through the graphite tube. Immediately after the copper liquid enters the short crystallizer, let the cooling water enter the cavity through the water inlet of the short crystallizer. The pressure of the cooling water is 0.17 MPa to 0.25 MPa; conduct initial casting. The initial casting speed is half of the stable casting speed. When the liquid level of the copper liquid in the crystallizer is 30 mm to 40 mm from the upper edge of the short crystallizer, enter stable casting. At this time, the graphite tube is immersed in the copper liquid in the short crystallizer. The stable casting speed is 5.6 m / h to 6.3 m / h. Use roasted red soot to cover the copper liquid in the short crystallizer.

[0041] Step 6: The dummy bar head of the dummy bar system holds the ingot and moves downward. The cooling water sprays out through the water outlet holes of the short crystallizer and splashes onto the surface of the lifted ingot. The cooling water on the surface of the ingot is refracted onto the annular water baffle and then refracted onto the surface of the ingot again, repeating this process many times; continuously cast without interruption. When the copper liquid in the melting furnace is poured out or the length of the ingot reaches the set value, the casting ends, and take out the ingot to obtain a large-sized high-purity copper ingot.

[0042] Furthermore, in step 1, the short crystallizer 1 includes an inner sleeve 101; an outer sleeve 102 is provided on the outside of the inner sleeve 101, and a cavity is formed between the outer sleeve 102 and the inner sleeve 101; a water inlet 103 is provided on the side wall of the outer sleeve 102, and the water inlet 103 is connected to the cavity; a plurality of water outlet holes 104 are provided at the junction of the lower edge of the outer sleeve 102 and the inner sleeve 101, and the water outlet holes 104 are semicircular and connected to the cavity, and the water outlet holes 104 are evenly distributed in the circumference of the lower edge of the outer sleeve 102.

[0043] Furthermore, the distance between the centers of each two adjacent water outlet holes 104 is 9 mm to 9.5 mm, the center line of the water outlet hole 104 forms an angle of 45° to 60° with the horizontal plane, the diameter of the water outlet hole 104 is 4 mm to 6 mm, and the height of the short crystallizer 1 is 130 mm to 180 mm.

[0044] Furthermore, in step 1, the annular water retainer 2 is prepared: after the rectangular metal plate is rolled into a cylinder, the seams are welded to obtain the annular water retainer 2; the rectangular metal plate is iron or ordinary carbon steel, the thickness of the rectangular metal plate is 2 mm to 4 mm, the height of the annular water retainer 2 is 130 mm to 200 mm, and the inner diameter of the annular water retainer 2 is 10 mm to 25 mm larger than the diameter of the lower edge of the inner sleeve.

[0045] Example 1.

[0046] The present invention is used to produce high-purity copper ∮300mm round ingots.

[0047] 1. A short crystallizer 1 comprises an inner sleeve 101; an outer sleeve 102 is provided on the outer surface of the inner sleeve 101, and a cavity is formed between the outer sleeve 102 and the inner sleeve 101; a water inlet 103 is provided on the side wall of the outer sleeve 102, and the water inlet 103 is connected to the cavity; 100 water outlet holes 104 are provided at the junction of the lower edge of the outer sleeve 102 and the inner sleeve 101. The water outlet holes 104 are semicircular and have a diameter of 5 mm. The water outlet holes 104 are connected to the cavity and are evenly distributed around the circumference of the lower edge of the outer sleeve 102. The center lines of the water outlet holes 104 form an angle of 55° with the horizontal plane. The height of the short crystallizer 1 is 150 mm. The diameter of the lower edge of the inner sleeve 101 is ∮309 mm, and the diameter of the upper edge of the inner sleeve 101 is ∮311 mm.

[0048] 2. Preparation of the annular water retainer 2: After the rectangular metal plate is rolled into a cylinder, the seams are welded to obtain the annular water retainer 2; the rectangular metal plate is ordinary carbon steel, the thickness of the rectangular metal plate is 3mm, the height of the annular water retainer 2 is 160mm, and the inner diameter of the ring of the annular water retainer 2 is 325mm.

[0049] 3. A method for preparing a high-purity copper ∮300 mm round ingot comprises the following steps:

[0050] Step 1: Install the short crystallizer 1 on the movable casting trolley. The center line of the short crystallizer 1 is perpendicular to the ground plane. The annular water baffle 2 is welded and installed at a position 15 mm directly below the short crystallizer 1 through the metal rod 3, and is on the same center line as the short crystallizer 1.

[0051] Step 2: Raise the dummy bar system that lifts the ingot in the casting well, and finely adjust the movable casting trolley so that the dummy bar head of the dummy bar system is inserted into the short crystallizer 1. The dummy bar head is inserted into the short crystallizer 1 at a position 1 / 3 from the lower edge. The dummy bar head, the short crystallizer 1, and the annular water baffle 2 are on the same center line. Block the gap between the dummy bar head and the short crystallizer 1 with asbestos cloth.

[0052] Step 3: Preheat the graphite tube. Insert one end of the preheated graphite tube into the furnace head of the melting furnace and lock it in place. Tilt the furnace head so that the other end of the graphite tube is inserted into the center of the short crystallizer 1. The end of the graphite tube inserted into the center of the short crystallizer is set at a position 55 mm from the upper edge of the short crystallizer 1. A flow-limiting valve is installed at the end of the graphite tube inserted into the furnace head. During casting, the flow rate of the copper liquid is controlled through the flow-limiting valve to control the casting speed. At this time, the flow-limiting valve is in the closed state.

[0053] Step 4: Tilt the furnace body. The copper liquid flows into the furnace head and heats the furnace head for 25 minutes to fully preheat the furnace head. Then adjust the temperature of the copper liquid to 1200 °C, let it stand for 4 minutes and keep it warm. Fine-tune the furnace body so that the graphite tube embedded in the furnace head is aligned with the center of the short crystallizer 1 and perpendicular to the horizontal plane of the short crystallizer 1.

[0054] Step 5: Open the flow-limiting valve. The copper liquid enters the short crystallizer 1 through the graphite tube. Immediately after the copper liquid enters the short crystallizer 1, cooling water enters the cavity through the water inlet 103. The cooling water enters the cavity of the short crystallizer 1 to cool the copper liquid and make it crystallize into a shell. The pressure of the cooling water is 0.19 MPa. The initial casting speed is 3.0 m / h. When the liquid level of the copper liquid in the short crystallizer 1 is 35 mm from the upper edge of the short crystallizer 1, normal and stable casting begins. At this time, the graphite tube is immersed in the copper liquid in the short crystallizer 1, and the casting speed is 5.9 m / h. Use roasted red soot to cover the copper liquid in the short crystallizer 1 to protect the copper liquid from being polluted and keep it properly warm.

[0055] Step 6: The dummy bar head lifts the ingot and moves downward. The cooling water sprays out through the water outlet hole 104 at the lower edge of the short crystallizer 1 and splashes onto the surface of the lifted ingot, quickly cooling the ingot. The annular water baffle 2 surrounds the ingot and covers the water refracted from the surface of the ingot. When the water encounters the annular water baffle 2, it is refracted back to the surface of the ingot again, repeating many times to take away the heat of the ingot and strengthen the cooling of the ingot in the high-temperature state. Continuously cast without interruption. When the copper liquid in the melting furnace is poured out or the length of the ingot reaches the set value, the casting ends, and a high-purity copper ∮300 mm circular ingot is obtained. The melting furnace body returns to its original position. Move the movable casting trolley away, take out the ingot, and the casting system returns to its original position.

[0056] Example 2.

[0057] Using the present invention to produce a high-purity copper ∮330mm circular ingot

[0058] 1. The short mold 1 includes an inner sleeve 101; an outer sleeve 102 is sleeved outside the inner sleeve 101, and a cavity is formed between the outer sleeve 102 and the inner sleeve 101; a water inlet 103 is arranged on the side wall of the outer sleeve 102, and the water inlet 103 is communicated with the cavity; 110 water outlet holes 104 are arranged at the junction of the lower edge of the outer sleeve 102 and the inner sleeve 101. The water outlet holes 104 are semicircular with a diameter of 5mm. The water outlet holes 104 are communicated with the cavity. The water outlet holes 104 are evenly distributed in the circumferential direction of the lower edge of the outer sleeve 102. The center line of the water outlet holes 104 forms an angle of 55° with the horizontal plane. The height of the short mold 1 is 155mm. The diameter of the lower edge of the inner sleeve 101 is ∮340mm, and the diameter of the upper edge of the inner sleeve 101 is ∮342mm.

[0059] 2. Preparation of the annular water baffle 2: After rolling a rectangular metal plate into a cylinder, welding the seam to obtain the annular water baffle 2; the rectangular metal plate is ordinary carbon steel, the thickness of the rectangular metal plate is 3mm, the height of the annular water baffle 2 is 160mm, and the inner diameter of the ring of the annular water baffle 2 is 358mm.

[0060] 3. A method for preparing a high-purity copper ∮330mm circular ingot, comprising the following steps:

[0061] Step 1: Install the short mold 1 on a movable casting trolley, and the center line of the short mold 1 is perpendicular to the ground plane; the annular water baffle 2 is welded and installed at a position 15mm directly below the short mold 1 through a metal rod 3, and is on the same center line as the short mold 1;

[0062] Step 2: The ingot guiding system for lifting the ingot in the casting well rises, and finely adjust the movable casting trolley so that the ingot guiding head of the ingot guiding system is inserted into the short mold 1. The ingot guiding head is inserted into the short mold 1 at a position 1 / 3 from the lower edge. The ingot guiding head, the short mold 1, and the annular water baffle 2 are on the same center line, and the gap between the ingot guiding head and the short mold is blocked with asbestos cloth;

[0063] Step 3: Preheat the graphite tube, insert one end of the preheated graphite tube into the furnace head of the melting furnace and lock it firmly, tilt the furnace head so that the other end of the graphite tube is inserted into the center of the short mold 1. The end of the graphite tube inserted into the center of the short mold is arranged at a position 55mm from the upper edge of the short mold 1; a flow limiting valve is installed at the end of the graphite tube inserted into the furnace head. During casting, control the flow rate of the molten copper through the flow limiting valve to control the casting speed; at this time, the flow limiting valve is in a closed state;

[0064] Step 4: Tilt the furnace body so that the copper liquid flows into the furnace head and heats the furnace head for 25 minutes to fully preheat the furnace head. Then adjust the temperature of the copper liquid to 1205°C, let it stand for 5 minutes and keep it warm. Fine-tune the furnace body so that the graphite tube embedded in the furnace head is aligned with the center of the short crystallizer 1 and perpendicular to the horizontal plane of the short crystallizer.

[0065] Step 5: Open the flow-limiting valve. The copper liquid enters the short crystallizer 1 through the graphite tube. Immediately after the copper liquid enters the short crystallizer 1, cooling water enters the cavity through the water inlet 103. The cooling water cools the copper liquid in the cavity of the short crystallizer 1 to make it crystallize into a shell. The pressure of the cooling water is 0.20 MPa. The initial casting speed is 2.9 m / h. When the liquid level of the copper liquid in the short crystallizer 1 is 35 mm away from the upper edge of the short crystallizer 1, enter the normal stable casting. At this time, the graphite tube is immersed in the copper liquid in the short crystallizer 1, and the casting speed is 5.8 m / h. Use roasted red soot to cover the copper liquid in the short crystallizer 1 to protect the copper liquid from being contaminated and keep it warm appropriately.

[0066] Step 6: The dummy bar holder lifts the ingot and moves it downward. The cooling water sprays out through the water outlet hole 104 at the lower edge of the short crystallizer 1 and splashes onto the surface of the lifted ingot, so that the ingot is quickly cooled. The annular water baffle 2 surrounds the ingot and covers the water refracted from the surface of the ingot. After the water encounters the annular water baffle 2, it is refracted to the surface of the ingot again, repeating many times to take away the heat of the ingot and strengthen the cooling of the ingot in the high-temperature state. Continuously cast without interruption. When the copper liquid in the melting furnace is poured out or the length of the ingot reaches the set value, the casting ends, and a high-purity copper ∮330 mm round ingot is obtained. The melting furnace body returns to its original position. Move the movable casting trolley away, take out the ingot, and the casting system returns to its original position.

[0067] Using a conventional crystallizer with a height of 250 mm and without an annular water baffle, the cross-sectional structure of the ∮330 mm ingot cast is as Figure 4 shown in b; the cross-sectional structure of the ingot prepared in Example 2 of the present invention is as Figure 4 shown in a; it can be Figure 4 seen by comparison that the inside of the ingot prepared in Example 2 of the present invention is uniform and fine.

Claims

1. A method for preparing a large-sized high-purity copper ingot, characterized in that, It includes the following steps: Step 1: Install the short crystallizer on the movable casting trolley, with the center line of the short crystallizer perpendicular to the ground plane; the annular water baffle is installed directly below the short crystallizer by welding, and the annular water baffle and the short crystallizer are on the same center line; Step 2: Raise the dummy bar system in the casting well that holds the ingot, and finely adjust the movable casting trolley to insert the dummy bar head of the dummy bar system into the short crystallizer; Step 3: Preheat the graphite tube, insert one end of the preheated graphite tube into the furnace head of the melting furnace and lock it firmly, tilt the furnace head so that the other end of the graphite tube inserts into the center of the short crystallizer; a flow limiting valve is installed at the end of the graphite tube inserted into the furnace head, and at this time the flow limiting valve is in the closed state; Step 4: Tilt the furnace body, let the copper liquid flow into the furnace head, heat the furnace head for a certain time, then adjust the temperature of the copper liquid, let it stand for a certain time and keep it warm, and adjust the furnace body so that the graphite tube inserted into the furnace head is aligned with the center of the short crystallizer and perpendicular to the horizontal plane of the short crystallizer; Step 5: Open the flow limiting valve, the copper liquid enters the short crystallizer through the graphite tube, and immediately after the copper liquid enters the short crystallizer, make the cooling water enter the cavity through the water inlet of the short crystallizer, and the pressure of the cooling water is 0.17 MPa - 0.25 MPa; carry out initial casting, and the initial casting speed is half of the stable casting speed. When the liquid level of the copper liquid in the short crystallizer is 30 mm - 40 mm away from the upper edge of the short crystallizer, enter stable casting. At this time, the graphite tube is immersed in the copper liquid in the short crystallizer, and the stable casting speed is 5.6 m / h - 6.3 m / h; Step 6: The dummy bar head of the dummy bar system holds the ingot and moves downward, and the cooling water sprays out through the water outlet holes of the short crystallizer and splashes onto the surface of the lifted ingot. The cooling water on the surface of the ingot is refracted onto the annular water baffle and then refracted onto the surface of the ingot again, repeating this many times; Carry out continuous casting without interruption. When the copper liquid in the melting furnace is poured out or the length of the ingot reaches the set value, the casting ends, take out the ingot, and obtain a large - size high - purity copper ingot; In the above - mentioned Step 1, the short crystallizer (1) includes an inner sleeve (101); an outer sleeve (102) is sleeved outside the inner sleeve (101), and a cavity is formed between the outer sleeve (102) and the inner sleeve (101); a water inlet (103) is arranged on the side wall of the outer sleeve (102), and the water inlet (103) is communicated with the cavity; a plurality of the water outlet holes (104) are arranged at the junction of the lower edge of the outer sleeve (102) and the inner sleeve (101), the water outlet holes (104) are semi - circular, the water outlet holes (104) are communicated with the cavity, and the water outlet holes (104) are evenly distributed in the circumferential direction of the lower edge of the outer sleeve (102); the distance between the centers of every two adjacent water outlet holes (104) is 9 mm - 9.5 mm, and the center line of the water outlet hole (104) forms an angle of 45º - 60º with the horizontal plane; In the above - mentioned Step 1, the preparation of the annular water baffle (2): After rolling a rectangular metal plate into a cylinder, weld the joint to obtain the annular water baffle (2); the height of the annular water baffle (2) is 130 mm - 200 mm; the inner diameter of the annular water baffle (2) is 10 mm - 25 mm larger than the diameter of the lower edge of the inner sleeve; In the said step 1, the distance between the annular water retainer (2) and the short mold (1) is 10 mm to 20 mm.

2. The preparation method of the large-size high-purity copper ingot according to claim 1, wherein, The diameter of the water outlet hole (104) is 4 mm to 6 mm, and the height of the short mold (1) is 130 mm to 180 mm.

3. The preparation method of the large-size high-purity copper ingot according to claim 1, characterized in that, The rectangular metal plate is made of iron or ordinary carbon steel; the thickness of the rectangular metal plate is 2 mm to 4 mm.

4. The preparation method of the large-size high-purity copper ingot according to claim 1, characterized in that In the said step 2, the dummy bar head stops at the position of 1 / 3 of the lower edge of the short mold (1), and the gap between the dummy bar head and the short mold (1) is blocked with asbestos cloth.

5. The preparation method of the large-sized high-purity copper ingot according to claim 1, wherein, In the said step 3, one end of the graphite tube inserted into the center of the short mold is set at the position of 50 mm to 55 mm from the upper edge of the short mold (1), and the graphite tube is perpendicular to the horizontal plane of the short mold (1).

6. The preparation method of the large-size high-purity copper ingot according to claim 1, characterized in that, In the said step 4, the time for heating the furnace head is 20 minutes to 30 minutes, the temperature of the copper liquid is adjusted to 1195 °C to 1215 °C, and the standing time is 3 minutes to 5 minutes.

7. The preparation method of the large-size high-purity copper ingot according to claim 1, wherein, In the said step 5, the molten copper in the short mold is covered with roasted red soot.

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