High-quality recycled up-drawing oxygen-free copper rod and preparation method and application thereof

Abstract

The application discloses a high-quality regenerated upward-drawing oxygen-free copper rod and a preparation method and application thereof, and belongs to the field of copper alloys. In the preparation, the proportion of the regenerated copper in the raw material for melting is higher than 40%. Even if sorted, the impurities are relatively high. Therefore, the application sequentially carries out melting and refining after sorting, controls the proportion of the exposed area of the copper water to the weight of the copper water in the melting process, and finely controls the proportion of the input flow of the mixed gas to the feeding amount per unit time in the refining process, so that the high-quality regenerated upward-drawing oxygen-free copper rod is prepared, the contents of O, P, Pb, Zn and S are less than 10ppm, and the content of other metal impurities is lower than 5ppm. The high-quality regenerated upward-drawing oxygen-free copper rod prepared by the method is applied to oxygen-free copper bars or mineral copper.

Description

Technical Field

[0001] This invention relates to the field of copper alloys, specifically to a high-quality recycled oxygen-free copper rod, its preparation method, and its application. Background Technology

[0002] As high-speed rail reaches the end of its service life, the amount of scrap copper resources generated from decommissioned high-speed rail lines increases. However, most of the recycled copper from dismantling and recycling can only be used in downgraded applications in the copper alloy field. The main reason is that the recycled copper contains excessive levels of impurities, such as Fe, Ni, Pb, and Sn, and its utilization efficiency is low. It is rarely used in pure copper products, and it is even more difficult to use recycled copper to directly produce oxygen-free copper rods.

[0003] Therefore, when using recycled copper to produce oxygen-free copper rods, reducing the oxygen content while ensuring that the impurity elements meet the requirements is a technical challenge.

[0004] Chinese patent CN117816917A discloses a method for preparing oxygen-free copper rods. This method uses an electrolytic plate to prepare oxygen-free copper rods. It mainly involves introducing nitrogen into the molten copper through multiple gas pipes in a smelting furnace, while using chestnut charcoal with good degassing effect to control the oxygen content of the copper rod to below 1 ppm. However, the recycled copper has a high impurity content and cannot be used for production.

[0005] Chinese Patent CN103114208A discloses a method for producing oxygen-free copper rods from recycled copper, comprising the following steps: A. Charging recycled copper into a furnace and heating to melt it; B. Refining to remove metallic impurities; C. Reduction with natural gas to obtain pure copper; D. Adding rare earth elements and a composite deoxidizer before tapping the copper; E. Casting and continuous casting and rolling to obtain oxygen-free copper rods. The advantages of this invention are: compared to the traditional top-drawing method, it can utilize readily available recycled copper as raw material and process large quantities of recycled copper at once, overcoming the shortcomings of the top-drawing method, which uses recycled copper but has high production costs and low efficiency; it uses natural gas reduction instead of wood-based reduction, which is more environmentally friendly, lower in cost, and requires less manual labor, overcoming the harsh working conditions of wood-based reduction. However, this method has too many steps and can only be used with continuous casting and rolling, resulting in copper rods with high oxygen content.

[0006] Therefore, given the shortcomings of the existing technology, there is an urgent need to design a method for producing high-quality upward-drawing oxygen-free copper rods using recycled copper. Summary of the Invention

[0007] This invention provides a method for preparing high-quality recycled oxygen-free copper rods. The method has a high utilization rate of recycled copper and produces oxygen-free copper rods with low impurity and oxygen content.

[0008] This invention provides a method for preparing high-quality recycled oxygen-free copper rods, the process flow of which includes: crushing, sorting, melting, refining and continuous casting of recycled copper raw materials. The melting process includes: adding raw materials to molten copper per unit time, the raw materials comprising sorted recycled copper and refining agents, wherein the weight percentage of the sorted recycled copper in the raw materials is more than 40%, and the ratio of the exposed area of ​​the molten copper to the weight of the molten copper is 0.02~0.1m². 2 / t; The refining process includes: introducing a mixed gas into the bottom of the molten copper, wherein the ratio of the gas flow rate of the mixed gas to the amount of raw materials fed per unit time is 0.5~5:1 L / kg, wherein the unit of gas flow rate per unit time is liters per hour, and the unit of raw material feeding per unit time is kilograms per hour, and the mixed gas contains carbon monoxide.

[0009] Because the raw materials provided by this invention contain a high proportion of recycled copper, even after sorting, the impurity content remains high. This invention exposes an appropriate area of ​​the molten copper to the outside, oxidizing the impurity elements in the molten copper by introducing oxygen. The oxidized impurity elements are then effectively removed by the action of a refining agent. However, the exposed area must be commensurate with the weight of the molten copper. If the exposed area is too high, the introduced oxygen content will be too high, making it impossible to control the oxygen content of the molten copper in the melting stage at 30-50 ppm. If the exposed area is too low, the impurity elements cannot be effectively removed.

[0010] This invention controls the ratio of the mixed gas flow rate to the amount of raw materials added during the melting process, ensuring sufficient mixed gas to remove oxygen and impurities from a high proportion of recycled copper during refining. This maintains the oxygen content in the molten copper at a stable level below 20 ppm. Insufficient gas flow results in excessive oxygen content in the molten copper, while excessive flow causes significant fluctuations in the melt surface, leading to incomplete surface coverage. Furthermore, excessive flow can prevent some gas from escaping from the transition chamber and instead enter the holding furnace with the molten copper. Consequently, some gas enters the casting crystallizer within the holding furnace, resulting in porosity in the cast copper rod and affecting product quality.

[0011] Preferably, the weight percentage of the sorted recycled copper in the raw material is 50% to 80%.

[0012] Preferably, in the refining process, the ratio of the gas flow rate of the mixed gas to the amount of raw materials input per unit time is 1~5:1 L / kg.

[0013] This invention further controls the gas flow rate within a higher range, thereby enabling the oxygen content of the molten copper during the refining process to be controlled below 10 ppm.

[0014] Preferably, the weight percentage of the sorted recycled copper in the raw material is a%, where 40 ≤ a < 60, and the ratio of the gas flow rate of the mixed gas to the amount of raw material input per unit time is m, where 0.5:1 ≤ m < 2:1 L / kg, and the unit of m is L / kg.

[0015] In the mixed gas, carbon monoxide mainly reacts with cuprous oxide in the molten copper to reduce it to copper, generating carbon dioxide which escapes from the melt. Nitrogen in the mixed gas adsorbs oxides in the molten copper and causes them to float to the surface. When the proportion of recycled copper in the raw material is low, i.e., the oxygen and impurity content is not high, less oxygen and oxide impurities need to be removed per unit time, so the flow rate can be reduced. However, the ratio cannot be less than 0.5:1, otherwise the removal of oxygen and impurity elements will be incomplete, leading to oxygen content and some impurity elements exceeding the requirements. Furthermore, because less oxygen and oxide impurities are removed, this invention limits the upper limit of the gas flow rate, ensuring that the introduced gas is still diffused tiny bubbles with a suitable floating speed, making it more suitable for removing oxygen and impurities from slightly lower content recycled copper.

[0016] Preferably, the weight percentage of the sorted recycled copper in the raw material is b%, where 60 ≤ b ≤ 100, and the ratio of the gas flow rate of the mixed gas to the amount of raw material input per unit time is n, where 2:1 ≤ n ≤ 5:1 L / kg, and the unit of n is L / kg.

[0017] Preferably, the recycled copper raw material is crushed to obtain copper granules with a size of 1-5 mm. This invention, by crushing the raw material into suitable sizes, facilitates subsequent sorting and minimizes the amount of copper raw material carried away by impurities during sorting.

[0018] Preferably, the sorting process consists of magnetic separation, air separation, and color separation, wherein the magnetic field strength of the magnetic separation is 2000~2500Gs, and the recycled copper raw material is crushed to obtain copper granules with a size of 2~4mm.

[0019] This invention controls the magnetic field strength and the size of the copper granules. Through the synergistic effect of the two, magnetic impurities can be effectively screened out from the copper granules, and the loss of copper raw materials caused by magnetic impurities carrying away the copper granules can be minimized.

[0020] More preferably, during the magnetic process, the copper granules are transported at a rate of 0.6 to 1.0 m / s, and the thickness of the copper granules is 50 to 80 mm.

[0021] More preferably, the wind speed of the wind sorting is 1.5~3.0m / s, and the recognition accuracy of the color sorting is 1~3mm micro-color difference.

[0022] More preferably, the color sorting carry-out ratio is 1:1 to 1:3. The carry-out ratio provided by this invention is the ratio of good material to bad material selected by color sorting.

[0023] Preferably, the sorting is performed two or more times.

[0024] Preferably, the number of sorting operations is 2 to 4.

[0025] The recycled copper obtained after sorting by this invention has a copper content of ≥99.98wt%, zinc ≤0.004wt%, tin ≤0.003wt%, lead ≤0.003wt%, iron ≤0.003wt%, nickel ≤0.002wt%, aluminum ≤0.002wt%, and phosphorus ≤0.002wt%.

[0026] Preferably, the recycled copper is copper scrap, mainly referring to copper-silver wire, copper-magnesium wire, copper conductor, busbar, shielding copper mesh, copper braided tape, etc.

[0027] Preferably, before melting, the sorted recycled copper and refining agent are mixed evenly and dried. The amount of refining agent added is 0.5-5% of the weight of the sorted recycled copper. The refining agent includes: 50-70 wt% SiO2 powder, 10-30 wt% CaO powder, and 10-30 wt% potassium dihydrogen phosphate powder.

[0028] In the refining agent provided by this invention, potassium dihydrogen phosphate decomposes into potassium oxide and phosphorus pentoxide at high temperatures. During the melting process, phosphorus pentoxide reacts with metal oxides (alumina, nickel oxide, zinc oxide, lead oxide, iron oxide, etc.) in the recycled copper raw material to form phosphoric acid compounds. These metal phosphoric acid compounds then react with silicon dioxide to form potassium-phosphorus-silicon composite slag that floats to the surface. The CaO powder in the refining agent is alkaline and is mainly used to neutralize the acidic phosphorus pentoxide, lowering the melting point of the phosphate slag and preventing the slag from hardening and encapsulating the molten copper, thus reducing copper loss. Since this project uses copper-based scrap copper, and the impurities in the recycled raw material are further reduced after sorting, the proportion of potassium dihydrogen phosphate is controlled below 30%. If the potassium dihydrogen phosphate content is too high, some phosphorus will enter the molten copper, increasing the phosphorus content of impurities. However, if it is below 10%, the impurity removal effect is not significant. SiO2 powder is mainly used as a slag-forming agent and does not react with molten copper at high temperatures, so it does not form slag sufficiently. Its proportion is controlled at 50-70 wt%, and a small amount of CaO powder is added to neutralize the acidity and alkalinity of the slag layer and reduce the risk of agglomeration.

[0029] More preferably, the drying temperature is 100~200℃, the time is 1~6h, and the atmosphere is nitrogen protection.

[0030] Preferably, during melting, the surface of the molten copper is covered with charcoal, with some of the molten copper exposed, and the temperature of the molten copper is 1180~1200℃.

[0031] Preferably, the raw materials added to the molten copper during melting also include an electrolytic plate.

[0032] In this invention, the oxygen content of the copper molten metal in the melting furnace is measured every half hour using an oxygen analyzer. The oxygen content of the copper molten metal in the melting furnace is preferably controlled at 30~50ppm (according to the calculation formula of hydrogen-oxygen balance of copper melt, at this time the hydrogen content is less than 3ppm, and the probability of porosity of the upward casting billet is greatly reduced).

[0033] Preferably, during the refining process, the mixed gas also includes argon, and the volume ratio of carbon monoxide in the mixed gas is 50-80%. This invention, by providing an appropriate amount of carbon monoxide, can effectively remove oxygen from molten copper.

[0034] Preferably, during the refining process, the bottom-blowing pressure at the bottom of the molten copper is 0.2~0.6 MPa. This invention, by controlling the bottom-blowing pressure at the bottom of the molten copper, allows the mixed gas to be smoothly introduced into the molten copper for deoxygenation, and also reduces the possibility of surface turbulence in the molten copper, thus reducing the entry of external oxygen. It should be understood that the bottom-blowing pressure provided by this invention refers to the gas pressure of the furnace bottom blowing device.

[0035] Preferably, during the refining process, a mixed covering agent is applied to the surface of the molten copper. The mixed covering agent comprises carbon particles and graphite flakes, and the thickness of the mixed covering agent is 15-20 cm.

[0036] Preferably, the refining process is carried out in a transition chamber, which is sealed with an iron plate.

[0037] Preferably, the process of upward continuous casting includes: the temperature of the molten copper is 1140~1160℃, the inlet water temperature is 25~40℃, the outlet water temperature is not higher than the inlet water temperature by 20℃, the pitch of the cast copper rod is 2~8mm, and the casting reverse thrust distance is 0.1~1mm.

[0038] More preferably, the back-pull distance in the casting process accounts for 10-30% of the pitch. The main purpose of back-pull is to reduce the depth of crystallization lines formed during the casting process. If the back-pull distance is too long, it will far exceed the width of the crystallization lines, causing the already solidified part to melt again, which in turn leads to the formation of secondary crystallization lines. If the back-pull distance is too short, it cannot effectively reduce the depth of the crystallization lines.

[0039] Preferably, in the upward continuous casting, the temperature of the billet exiting the crystallizer is 40~80℃, and the temperature fluctuation range of the crystallizer does not exceed 10℃.

[0040] This invention controls the temperature and temperature fluctuation range of the crystallizer billet to minimize slight oxidation on the billet surface, thereby preventing excessively high oxygen content in subsequent continuous extrusion products. Simultaneously, it controls the cooling rate of the molten copper in the crystallizer to ensure effective gas escape, minimizing the presence of microbubbles in the billet. However, it also avoids excessively rapid cooling, which could lead to deep crystallization lines and gas ingress during subsequent continuous extrusion, causing extrusion blistering. Furthermore, by controlling the crystallizer temperature, this invention enhances crystallizer stability and prevents the formation of hollow defects.

[0041] Preferably, in the upward continuous casting, the fluctuation range of the copper liquid level is controlled within ±10mm.

[0042] On the other hand, the present invention provides a high-quality regenerated upward-drawing oxygen-free copper rod, which is prepared by the method for preparing the high-quality regenerated upward-drawing oxygen-free copper rod.

[0043] Preferably, the high-quality recycled oxygen-free copper rod has an O, P, Pb, Zn, and S element content of less than 10 ppm, an other metal impurity content of less than 5 ppm, and an up-drawing copper rod conductivity of greater than 100.5% IACS.

[0044] On the other hand, the present invention also provides the application of the high-quality regenerated oxygen-free copper rod on oxygen-free copper busbars or copper ore.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows: The raw materials used in this invention contain over 40% recycled copper, and even after sorting, they still contain high levels of impurities. Therefore, this invention involves sequentially melting and refining the raw materials after sorting. During the melting process, the ratio of the exposed area of ​​molten copper to the weight of the molten copper is controlled. During the refining process, the ratio of the flow rate of the mixed gas to the amount of material fed per unit time is precisely controlled. This results in high-quality recycled oxygen-free copper rods with low impurity and oxygen content. Attached Figure Description

[0046] Figure 1 Metallographic image of the upward-drawing copper rod obtained in Example 1 (magnified 50 times). Figure 2 The image shown is a scanning electron microscope image (20,000x magnification) of the upward-drawing copper rod obtained in Example 1. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited to the following embodiments.

[0048] Example 1 This embodiment provides a method for preparing a φ16mm upward-drawing oxygen-free copper rod with a regeneration ratio of 50%, including: (1) Sorting and crushing of recycled copper raw materials: The recycled copper products are sorted, and obvious iron-containing parts, nickel-plated parts and other metal parts are picked out. The remaining parts are shredded into small pieces of less than 2cm by a shredder and then crushed into copper granules of 1~2mm by a high-speed copper block crusher.

[0049] (2) Sorting: The broken copper granules are first subjected to magnetic separation and air separation, and then color separation. The sorting is carried out twice. The magnetic field strength is 2300Gs during magnetic separation, the belt speed is 0.8m / s, the thickness of the material on the belt is about 60mm, and the wind speed is 1.5m / s during air separation. The color separation requires a recognition accuracy of 0.2mm micro color difference, and the carry-out ratio (bad material: good material) is 1:2.

[0050] After sorting, the content of copper is 99.985 wt%, zinc 0.003 wt%, tin 0.002 wt%, lead 0.002 wt%, iron 0.003 wt%, nickel 0.002 wt%, aluminum 0.002 wt%, and phosphorus 0.001 wt%.

[0051] (3) Pretreatment: Add 1% of refining agent to the copper granules according to the weight of the sorted copper granules, mix evenly and put them into a drying oven for baking. The drying temperature is 200℃ and the time is 6h. The atmosphere is nitrogen protection. The refining agent consists of 60wt% SiO2 powder + 20wt% CaO powder + 20wt% potassium dihydrogen phosphate powder.

[0052] (4) Melting: The pretreated copper granules, refining agent, and electrolytic plate are fed into the smelting furnace. The weight percentage of recycled copper after sorting in the raw materials is 50%. When adding the copper, the charcoal covering the surface of the smelting furnace is removed, and the molten copper is slightly exposed. The ratio of the exposed area of ​​the molten copper to its weight is 0.04 m². 2 / t, the temperature of the molten copper is controlled at 1180~1200℃, and the oxygen content of the molten copper in the melting furnace is measured every half hour using an oxygen analyzer. The oxygen content of the molten copper in the melting furnace is controlled at 30~40ppm.

[0053] (5) Refining in the transition chamber: A mixture of carbon monoxide and argon is blown into the transition chamber through a bottom blowing device pre-installed at the bottom. The carbon monoxide content is 60%, the bottom blowing gas flow rate (L / h) per unit time is 1.5 times the raw material input (kg / h), and the bottom blowing pressure is between 0.3MPa. The transition chamber is covered with high carbon particles (carbon content greater than 95%, moisture content less than 1%), mixed with graphite flakes. During the blowing process, the mixed covering agent is not exposed, and the mixed covering agent has a thickness of 20cm. The transition chamber is sealed with an iron plate. The copper flow path exceeds 800mm. Every 1 hour, the oxygen content of the copper in the transition chamber is determined to be less than 10ppm by an oxygen analyzer.

[0054] (6) Continuous casting in the holding furnace: The temperature of the copper molten metal in the holding furnace is controlled at 1150℃, the inlet water temperature is 25℃, the outlet water temperature is not more than 10℃ higher than the inlet water temperature, the pitch of the copper rod is 4mm, the reverse push distance is 0.5mm, the temperature of the rod billet exiting the crystallizer is not higher than 60℃, the temperature fluctuation is not more than 10℃, and the fluctuation range of the liquid level of the copper molten metal in the holding furnace is controlled within ±10mm.

[0055] Example 2 This embodiment provides a method for preparing a φ16mm upward-drawing oxygen-free copper rod with a regeneration ratio of 60%, including: (1) Sorting and crushing of recycled copper raw materials: The recycled copper products such as copper-silver wire, copper-magnesium wire, copper conductor, busbar, shielding copper mesh, copper braided tape, etc. are sorted out, and obvious iron parts, nickel parts and other metal parts are picked out. The remaining parts are crushed into small pieces of less than 2cm by a shredder and then crushed into copper granules of 1~2mm by a high-speed copper block crusher.

[0056] (2) Sorting: The broken copper granules are first subjected to magnetic separation and air separation, and then color separation. The sorting is carried out twice. The magnetic field strength is 2500Gs during magnetic separation, the belt speed is 0.8m / s, the belt feeding thickness is 50mm, and the air speed is 1.5m / s. The color separation requires a recognition accuracy of 0.2mm micro color difference, and the carry-out ratio (bad material: good material) is 1:2.

[0057] After sorting, the content of copper is 99.984 wt%, zinc 0.003 wt%, tin 0.003 wt%, lead 0.003 wt%, iron 0.002 wt%, nickel 0.002 wt%, aluminum 0.001 wt%, and phosphorus 0.001 wt%.

[0058] (3) Pretreatment: Add about 1.5% of refining agent to the copper granules after sorting, mix evenly and put them into a drying oven for baking. The drying temperature is 200℃ and the time is 6h. The atmosphere is nitrogen protection. The refining agent consists of 60wt% SiO2 powder + 15wt% CaO powder + 25wt% potassium dihydrogen phosphate powder.

[0059] (4) Melting: The pretreated copper granules, refining agent, and electrolytic plates are added to the melting furnace. The weight percentage of the sorted recycled copper is 80%. When adding the copper, the charcoal covering the surface of the melting furnace is removed, and the molten copper is slightly exposed. The ratio of the exposed area of ​​the molten copper to its weight is 0.06 m². 2 / t, the temperature of the molten copper is controlled at 1180~1200℃, and the oxygen content of the molten copper in the melting furnace is measured every half hour using an oxygen analyzer. The oxygen content of the molten copper in the melting furnace is controlled at 30~40ppm.

[0060] (5) Refining in the transition chamber: A mixture of carbon monoxide and argon is blown into the transition chamber through a bottom blowing device pre-installed at the bottom. The carbon monoxide content is 70%, the bottom blowing gas flow rate (L / h) per unit time is 2.5 times the amount of raw material input (kg / h), and the bottom blowing pressure is between 0.35MPa. The transition chamber is covered with high carbon particles (carbon content greater than 95%, moisture content less than 1%), mixed with graphite flakes. During the blowing process, the mixed covering agent is not exposed, and the mixed covering agent has a thickness of 20cm. The transition chamber is sealed with an iron plate. The copper flow path exceeds 800mm. Every 1 hour, the oxygen content of the copper in the transition chamber is determined to be less than 10ppm by an oxygen analyzer.

[0061] (6) Continuous casting in the holding furnace: The temperature of the copper molten metal in the holding furnace is controlled between 1140 and 1160°C, the inlet water temperature is between 25 and 30°C, the outlet water temperature is not more than 10°C higher than the inlet water temperature, the pitch of the copper rod is 4.5 mm, the reverse push distance is 0.6 mm, the temperature of the rod billet exiting the crystallizer is not higher than 60°C, the temperature fluctuation is not more than 10°C, and the fluctuation range of the liquid level of the copper molten metal in the holding furnace is controlled within ±10 mm.

[0062] Example 3 This embodiment provides a method for preparing a φ16mm upward-drawing oxygen-free copper rod with a regeneration ratio of 80%, including: (1) Sorting and crushing of recycled copper raw materials: The recycled copper products such as copper-silver wire, copper-magnesium wire, copper conductor, busbar, shielding copper mesh, copper braided tape, etc. are sorted out, and obvious iron parts, nickel parts and other metal parts are picked out. The remaining parts are crushed into small pieces of less than 2cm by a shredder and then crushed into copper granules of 1~2mm by a high-speed copper block crusher.

[0063] (2) Sorting: The broken copper granules are first subjected to magnetic separation and air separation, and then color separation. The sorting is carried out twice. The magnetic field strength is 2500Gs during magnetic separation, the belt speed is 0.6m / s, the thickness of the material on the belt is about 50mm, and the wind speed is 1.8m / s during air separation. The color separation requires a recognition accuracy of 0.2mm micro color difference, and the carry-out ratio (bad material: good material) is 1:1.

[0064] After sorting, the copper content is above 99.98 wt%, zinc below 0.004 wt%, tin below 0.003 wt%, lead below 0.003 wt%, iron below 0.003 wt%, nickel below 0.002 wt%, aluminum below 0.002 wt%, and phosphorus below 0.002 wt%.

[0065] (3) Pretreatment: Add 2.5% of the refining agent to the copper granules after sorting, mix evenly and put them into a drying oven for baking. The drying temperature is 100~200℃ and the time is 1~6h. The atmosphere is nitrogen protection. The refining agent consists of 60wt% SiO2 powder + 10wt% CaO powder + 30wt% potassium dihydrogen phosphate powder.

[0066] (4) Melting: The pretreated copper granules, refining agent, and electrolytic plates are fed into the melting furnace. The weight percentage of the sorted recycled copper is 60%. When adding the copper, the charcoal covering the surface of the melting furnace is removed, and the molten copper is slightly exposed. The ratio of the exposed area of ​​the molten copper to its weight is 0.06 m². 2 / t, the temperature of the molten copper is controlled at 1180~1200℃, and the oxygen content of the molten copper in the melting furnace is preferably controlled at 40~50ppm.

[0067] (5) Refining in the transition chamber: A mixture of carbon monoxide and argon is blown into the transition chamber through a bottom blowing device pre-installed at the bottom. The carbon monoxide content is 80%, the bottom blowing gas flow rate (L / h) per unit time is 3.0 times the raw material input (kg / h), and the bottom blowing pressure is 0.35MPa. The transition chamber is covered with high carbon particles (carbon content greater than 95%, moisture content less than 1%), mixed with graphite flakes. During the blowing process, the mixed covering agent is not exposed. The mixed covering agent covers a thickness of 20cm and the transition chamber is sealed with an iron plate. The copper flow path exceeds 800mm. Every 1 hour, the oxygen content of the copper in the transition chamber is determined to be less than 10ppm by an oxygen analyzer.

[0068] (6) Continuous casting in the holding furnace: The temperature of the copper molten metal in the holding furnace is controlled between 1140 and 1160°C, the inlet water temperature is between 25 and 30°C, the outlet water temperature is not more than 10°C higher than the inlet water temperature, the pitch of the copper rod is 4.5 mm, the reverse push distance is 0.6 mm, the temperature of the rod billet exiting the crystallizer is not higher than 60°C, the temperature fluctuation is not more than 10°C, and the fluctuation range of the liquid level of the copper molten metal in the holding furnace is controlled within ±10 mm.

[0069] Example 4 The difference from Example 1 is that the bottom blowing gas flow rate (L / h) per unit time is 0.5 times the amount of raw materials fed in (kg / h).

[0070] Example 5 The difference from Example 1 is that the magnetic field strength of the magnetic separation is 5000 Gs.

[0071] Comparative Example 1 Unlike Example 1, the bottom-blown gas flow rate (L / h) per unit time was 0.3 times the feed rate (kg / h). Due to the lower bottom-blown gas flow rate per unit time, the oxygen and impurity content in the copper rod was higher, as detailed in Table 1.

[0072] Comparative Example 2 Unlike Example 1, the ratio of the exposed area of ​​molten copper to its weight is 0.2 m². 2 / t, due to the large exposed area of ​​the copper molten copper, although the impurity content is low, excessive oxygen will be introduced, resulting in a high oxygen content, as detailed in Table 1.

[0073] Comparative Example 3 Unlike Example 1, the ratio of the exposed area of ​​molten copper to its weight is 0.01m². 2 / t, the exposed area of ​​the copper molten metal is relatively small, and even if mixed gas is subsequently introduced, the impurity content is still high, as detailed in Table 1.

[0074] The components and performance of the embodiments were tested, and the test data are shown in Tables 1 and 2.

[0075] Chemical composition (excluding oxygen content) is in accordance with "YS / T 482-2022 Analysis Methods for Copper and Copper Alloys - Spark Discharge Atomic Emission Spectrometry".

[0076] Oxygen content was tested in accordance with GB / T 5121.8-2024 Chemical Analysis Methods for Copper and Copper Alloys Part 8: Determination of Oxygen, Nitrogen and Hydrogen Content.

[0077] Conductivity testing was conducted in accordance with GB / T 351-2019 Method for Measurement of Resistivity of Metallic Materials.

[0078] Oxygen content measurement method in molten copper in melting and transition chamber: The oxygen content in molten copper is determined by an oxygen analyzer every half hour. Each measurement is taken three times, namely a1, a2, and a3. The difference between the three oxygen contents is within ±2ppm. If the difference exceeds ±2ppm, the measurement is repeated after 10 minutes. The three measurements are taken as the oxygen content of this measurement and recorded as A, where A = (a1 + a2 + a3) / 3.

[0079] Average oxygen content: Take the average of 5 oxygen measurements (i.e., after 2.5 hours of measurement, measure once every 0.5 hours), P = (A1 + A2 + A3 + A4 + A5) / 5.

[0080] The deviation value of oxygen content p = max|PA|, which is the average oxygen content P minus the absolute value of the oxygen content results of 5 measurements.

[0081] Table 1 shows the component test results of Examples 1-5 and Comparative Examples 1-3.

[0082] Table 2 shows the conductivity test results for Examples 1-5 and Comparative Examples 1-3.

[0083] As shown in Tables 1 and 2, the oxygen-free copper rods prepared in Examples 1 to 5 of this invention have O, Pb, Zn, and S element contents of less than 10 ppm, Fe, Sn, Ni, Al, and P element contents of less than 5 ppm, and high conductivity.

[0084] like Figure 1 As shown, the metallographic structure of the oxygen-free copper rod prepared in Example 1 is shown in the figure (50x magnification). The central part of the figure shows the equiaxed crystal structure after final cooling, while the others are dendritic crystals. There are no obvious pores in the structure, and no obvious oxide accumulation at the grain boundaries.

[0085] like Figure 2 As shown, the scanning electron microscope image (20,000x magnification) of the oxygen-free copper rod prepared in Example 1 shows that pores smaller than 1 μm can occasionally be seen at this magnification. The size of the pore in the image is 0.8 μm.

Claims

1. A method for preparing a high-quality regenerated upward-drawn oxygen-free copper rod, characterized in that, The process flow of the preparation method includes, in sequence: crushing, sorting, melting, refining and continuous casting of recycled copper raw materials; The melting process includes: adding raw materials to molten copper, the raw materials comprising sorted recycled copper and refining agents, wherein the weight percentage of the sorted recycled copper in the raw materials is more than 40%, and the ratio of the exposed area of ​​the molten copper to its weight is 0.02~0.1 m². 2 / t; The refining process includes: introducing a mixed gas into the bottom of the molten copper, wherein the ratio of the gas flow rate of the mixed gas to the amount of raw materials input per unit time is 0.5~5:1 L / kg, and the mixed gas contains carbon monoxide, wherein the volume ratio of carbon monoxide is 50~80%. Before melting, the sorted recycled copper and refining agent are mixed evenly and dried. The amount of refining agent added is 0.5-5% of the weight of the sorted recycled copper. The refining agent includes: 50-70 wt% SiO2 powder, 10-30 wt% CaO powder, and 10-30 wt% potassium dihydrogen phosphate powder.

2. The method for preparing high-quality regenerated upward-drawn oxygen-free copper rod according to claim 1, characterized in that, In the refining process, the ratio of the gas flow rate of the mixed gas to the amount of raw materials input per unit time is 1~5:1 L / kg.

3. The method for preparing high-quality regenerated upward-drawn oxygen-free copper rod according to claim 1, characterized in that, The weight percentage of the sorted recycled copper in the raw materials is a%, where 40 ≤ a < 60. The ratio of the gas flow rate of the mixed gas to the amount of raw materials input per unit time is m, where 0.5:1 ≤ m < 2:1, and the unit of m is L / kg.

4. The method for preparing high-quality regenerated upward-drawn oxygen-free copper rod according to claim 1, characterized in that, The weight percentage of the sorted recycled copper in the raw materials is b%, where 60≤b≤100, and the ratio of the gas flow rate of the mixed gas to the amount of raw materials input per unit time is n, where 2:1≤n≤5:1, and the unit of n is L / kg.

5. The method for preparing high-quality regenerated upward-drawn oxygen-free copper rod according to claim 1, characterized in that, The sorting process consists of magnetic separation, air separation, and color separation. The magnetic field strength of the magnetic separation is 2000~2500Gs. The recycled copper raw material is crushed to obtain copper granules with a size of 2~4mm.

6. The method for preparing high-quality regenerated upward-drawn oxygen-free copper rod according to claim 5, characterized in that, The wind speed for the air sorting is 1.5~3.0m / s, and the color sorting accuracy is 1~3mm for slight color difference.

7. The method for preparing high-quality regenerated upward-drawn oxygen-free copper rod according to claim 5, characterized in that, The color sorting carry-out ratio is 1:1 to 1:

3.

8. The method for preparing high-quality regenerated upward-drawn oxygen-free copper rod according to claim 1, characterized in that, During the melting process, charcoal covers the surface of the molten copper, leaving some of the molten copper exposed. The temperature of the molten copper is 1180 ~ 1200℃.

9. The method for preparing high-quality regenerated upward-drawn oxygen-free copper rod according to claim 1, characterized in that, During the refining process, the mixed gas also includes argon.

10. The method for preparing high-quality regenerated upward-drawn oxygen-free copper rod according to claim 1, characterized in that, During the refining process, the bottom blowing pressure at the bottom of the molten copper is 0.2~0.6MPa.

11. The method for preparing high-quality regenerated upward-drawn oxygen-free copper rod according to claim 1, characterized in that, During the refining process, a mixed coating agent is applied to the surface of the molten copper. The mixed coating agent comprises carbon particles and graphite flakes, and the thickness of the mixed coating agent is 15-20 cm.

12. A high-quality regenerated upward-drawn oxygen-free copper rod, characterized in that, It is prepared by the method for preparing high-quality regenerated upward-drawing oxygen-free copper rod according to any one of claims 1-11.

13. The high-quality regenerated upward-drawing oxygen-free copper rod according to claim 12, characterized in that, The high-quality recycled oxygen-free copper rod has an O, P, Pb, Zn, and S element content of less than 10 ppm, a other metal impurity content of less than 5 ppm, and an updrawing copper rod conductivity of greater than 100.5% IACS.

14. The application of a high-quality regenerated oxygen-free copper rod according to claim 12 or 13 on oxygen-free copper busbars or copper ore.

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